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UBC Theses and Dissertations

Mercury and artisanal and small-scale gold miners in China Gunson, Aaron James 2004

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Abstract This thesis determines that over four hundred thousand artisanal and small-scale gold miners all over China systematically use amalgamation and release approximately 240 tonnes o f mercury per annum. Artisanal and small-scale gold mining ( A S G M ) is one o f the largest sources o f mercury pollution i n China. This thesis outlines an approach to investigating A S G M in China based on a series o f three studies. The main findings o f the thesis were that A S G M and amalgamation are widespread i n China, and that mercury releases from A S G M have serious health and environmental impacts on the miners themselves  and on their  surrounding  communities and environment. The use o f whole ore amalgamation was demonstrated to be the primary source o f these releases, and Muller m i l l amalgamation was pinpointed as being responsible for over 70% o f the A S G M mercury releases. In addition, the practice o f following amalgamation with cyanidation was indicated to increase the solubility o f mercury and perhaps further increase its risks. The test work completed on an ore sample from the community o f " G o l d Mountain" demonstrated that alternative technology could largely replace whole ore amalgamation (although not cyanidation) with gravity methods and thus greatly mitigate the health and environmental impacts o f A S G M .  ii  Table of Contents n  ABSTRACT T A B L E OF C O N T E N T S  HI  L I S T OF T A B L E S  vm  L I S T OF F I G U R E S  ix  L I S T OF A B B R E V I A T I O N S  x  ACKNOWLEDGEMENTS  1  xu  Introduction  1  1.1  S T A T E M E N T OF P R O B L E M  1  1.2  BACKGROUND  2  Artisanal and Small-scale Mining  2  1.2.1  1.2.1.1  Definition  2  1.2.1.2  Extent and Impact  2  1.2.1.3  Health, Safety and Environment  3  1.2.1.4  Gender and Social Issues  4  1.2.1.5  Sustainable Livelihoods & Communities  4  1.2.2  Mercury as a Global Pollutant  5  1.2.3  Mercury as a Local Health Concern for ASGM.  8  1.2.3.1  Mercury Vapour  8  1.2.3.2  Methylmercury  10  1.3  2  O U T L I N E OF THESIS  12  Study One: Artisanal & Small-scale Gold Mining in China 2.1  '•  INTRODUCTION  2.1.1 2.2  14 14  Literature Review  14  METHODOLOGY  18  2.2.1  Site Visits  IS  2.2.2  Interviews  19  2.2.3  HgEXExpert System  20  2.3  RESULTS  2.3.1  2.3.1.1  22  Site Visits - Gold Processing Equipment and Methods in China  Muller Mills  22  22 iii  2.3.1.2  B a l l M i l l / Sluice  24  2.3.1.3  G o l d Dredges and Placer M i n i n g  25  2.3.1.4  Retorts  27  2.3.1.5  Cyanidation & Zinc Strip Smelting  28  2.3.1.6  G o l d Shops  29  2.3.2  Interviews  2.3.3  HgEXExpert  30 System  31  2.3.3.1  A l p h a Factor Determination for China  31  2.3.3.2  Bayuan Site Contamination  38  DISCUSSION - A S G M IN C H I N A  40  2.4  2.4.1  Significance of ASM  in China  2.4.2  Scale of ASGM in China  40 41  2.4.2.1  Definition  41  2.4.2.2  Scale o f A S G M in China  44  2.4.3  Economic Impact of ASGM  47  2.4.3.1  National Impact  47  2.4.3.2  Local Impact  48  2.4.3.3  Impact on Formal M i n i n g Companies  48  2.4.4  Legal Framework.  50  2AAA  Government Framework  50  2.4.4.2  Government Policy  50  2.4.4.3  Laws and Enforcement  51  2.4.4.4  Tax  53  2.4.4.5  Illegal A S G M  53  2.4.5  Social Context: ASGM in the Community  54  2.4.5.1  A S G M Labourers  54  2.4.5.2  A S G M Income  55  2.4.5.3  Women  55  2.4.5.4  Children  56  2.4.5.5  Labour Unions  56  2.4.6  Health, Safety, and Environmental Impact  56  2.4.7  Technical Assistance Programs  58  2.4.7.1  Technical Assistance  58 iv  2.4.7.2  Research Cooperation  58  2.4.7.3  Domestic Financial Institutions  59  2.4.7.4  Non-Governmental Organizations  59  2.4.7.5  Multilateral Organizations  59  2.5  3  CONCLUSION  60  Study Two: Artisanal and Small-scale Gold Miners in "Gold Mountain"  61  3.1  INTRODUCTION  61  3.2  " G O L D M O U N T A I N " - C A S E STUDY METHODOLOGY  61  3.3  " G O L D M O U N T A I N " C A S E STUDY- RESULTS  62  "Gold Mountain " Mining and Processing Practice  62  3.3.1 3.3.1.1  M i n i n g Practice  63  3.3.1.2  Comminution and Amalgamation  63  3.3.1.3  Retorts  65  3.3.1.4  Cyanidation and Zinc Smelting  67  3.3.1.5  G o l d Purification  68  3.3.1.6  " G o l d Mountain" A S G M Cost Structure  68  3.3.2  "Gold Mountain " Mercury Releases and Sample Collection  70  3.3.2.1  M i l l Operator Estimates on Mercury Lost  70  3.3.2.2  M i l l Data on Mercury Lost  70  3.3.2.3  Sample Collection Data on Mercury Lost  71  3.3.2.4  A S G M Mercury Release Estimates  71  3.3.3  ASGM Health and Environmental  Impact  72  3.3.3.1  Health Impact  72  3.3.3.2  " G o l d Mountain" Aquaculture  73  3.4  DISCUSSION  74  3.4.1  "Gold Mountain's " Processing Practice  74  3.4.2  Health and Environmental  3.5  4  Impact of Mercury Releases in "Gold Mountain"  3.4.2.1  Health Impact of Mercury Vapour  74  3.4.2.2  Bioaccumulation  75  CONCLUSION  76  Study Three: "Gold Mountain" Alternative Technology Test Program 4.1  ... 74  INTRODUCTION  77 77  V  4.1.1  Sample GM1 - "Gold Mountain " Feed Ore  77  4.1.2  Sample GM2 - "Gold Mountain " Muller Mill Tails  77  4.1.3  Sample GM3 - "Gold Mountain " Cyanidation  77  4.2 4.2.1  Tails  METHODOLOGY  78  Sample GM1 - "Gold Mountain " Feed  78  4.2.1.1  Sample Preparation and Characterization  79  4.2.1.2  Gravity Recovery Test  79  4.2.1.3  Gravity / Cyanidation Tests  80  4.2.2  Sample GM2 - "Gold Mountain " Muller Mill Tails  82  4.2.2.1  Sample Characterization  82  4.2.2.2  Gravity Recovery Test  83  4.2.2.3  Mercury Solubility Test  83  4.2.3  Sample GM3 - "GoldMountain"  Cyanidation  Tails  4.2.3.1  Sample Characterization  4.2.3.2  Gravity Recovery Test  84  4.2.3.3  Mercury Solubility Test  85  4.3 4.3.1  ".  84 84  RESULTS  85  Sample GM1 - "Gold Mountain " Feed  85  4.3.1.1  Sample Characterization  85  4.3.1.2  Gravity Recovery Test  85  4.3.1.3  Gravity / Cyanidation Tests  86  4.3.2  Sample GM2 - "Gold Mountain " Muller Mill Tails  89  4.3.2.1  Sample Characterization  89  4.3.2.2  Gravity Recovery Test  90  4.3.2.3  Mercury Solubility Test  91  4.3.3  Sample GM3 - "Gold Mountain " Cyanidation  Tails  91  4.3.3.1  S ample Characterization  91  4.3.3.2  Gravity Recovery Test  92  4.3.3.3  Mercury Solubility Test  93  4.4 4.4.1  DISCUSSION  93  "Gold Mountain " Samples  93  4.4.1.1  GM1  94  4.4.1.2  GM2  95 vi  4.4.1.3  4.4.2 4.5  5  G M 3  95  Mercury Solubility  96  CONCLUSION  97  Mercury Releases, Alternatives, and Implementation 5.1  98  CHINA'S M E R C U R Y RELEASES  98  5.1.1  Estimating China's ASGM Mercury Releases  98  5.1.2  Other Sources of Mercury  101  5.1.3  Comparing Mercury Releases in China  103  ALTERNATIVE TECHNOLOGY  104  5.2  5.2.1 5.3  5.3.1 5.4  Sustainable Alternative ASGM  Technology  107  TECHNOLOGY TRANSFER  112  ASGM Processing Centres  113  A S G M AND POLICY  116  6  Limitations and Bias  .  7  Areas for Additional Research  120  8  Conclusion  122  Bibliography Appendix  117  124 1  134  vii  List of Tables Table 1.1  A S M Production o f Various Minerals and Metals  3  Table 2.1  Site Visits, 2000-2002  18  Table 2.2  Chinese Productions o f Several Major Minerals  41  Table 2.3  Major health, safety, and environmental impacts o f A S M in China  57  Table 3.1  Typical M i n e r ' s Revenue and Profits Per Tonne o f Ore  69  Table 3.2  " G o l d Mountain" Processing Centre Data  70  Table 3.3  Muller M i l l Mercury Loss Estimates  71  Table 4.1  G M 1 Sample Characterization  85  Table 4.2  G M 1 - A Gravity Recoverable G o l d Test  85  Table 4.3  G M 1 - B Test Results  86  Table 4.4  G M 1 - C Test Results  86  Table 4.5  G M 1 - D Test Results  Table 4.6  G M 1 - B and G M 1 - C Cyanidation Tailings Analysis  88  Table 4.7  G M 2 Sample Characterization  90  Table 4.8  G M 2 Gravity Test Results  90  Table 4.9  G M 3 Sample Characterization  92  Table 4.10  G M 3 Gravity Test Results  92  Table 4.11  Mercury Solubility  93  Table 4.12  Grade Differences Between Test Samples  93  Table 5.1  Mercury to G o l d Loss Ratio for China  100  Table 5.2  Chinese Annual Mercury Releases attributable to A S G M  100  Table 5.3  L o w Estimate o f A S G M G o l d Production and Mercury Releases (2001)  101  Table 5.4  Chinese Sources o f Mercury Releases Due to M i n i n g (2001)  103  .'  viii  87  List of Figures Figure 1.1  Number of Artisanal & Small-scale Miners Around the World by Country  Figure 1.2  Eh (redox potential) versus pH for the Main Inorganic Mercury Species  11  Figure 2.1  Alpha Factor for HgEX  21  Figure 2.2  "Gold Mountain" Muller Mill  23  Figure 2.3  Jiangxi Ball-Mill Mercury Sluice Circuit  25  Figure 2.4  Guangxi Gravel/Gold Dredge Operation  Figure 2.5  "Gold Mountain" Gravel/Gold Operation  27  Figure 2.6  Jiangxi Province Retort Cooling Tube  28  Figure 2.7  "Gold Mountain" Zinc Strip Boxes  29  Figure 2.8  Burning Dore in Longsheng  30  Figure 2.9  Alpha Factor Comparison  37  Figure 2.10  ASGM Areas Across China  44  Figure 2.11  ASGM Tunnels, Boka, China  49  Figure 3.1  Cleaning the Concentrate From the Muller Mill  64  Figure 3.2  "Gold Mountain" Retort Diagram  66  Figure 3.3  "Gold Mountain" Retort Photo  66  Figure 3.4  Mercury Droplets from "Gold Mountain" Retort  67  Figure 4.1  GM1 Test Program  78  Figure 4.2  GM2 Test Program  82  Figure 4.3  GM3 Test Program  Figure 4.4  GM 1-D Leach Time  87  Figure 4.5  GM1-B and GM1-C Cyanidation Tailings Analysis  88  Figure 4.6  GM2 Size, Gold, and Mercury Distributions  89  Figure 4.7  GM3 Size, Gold, and Mercury Distributions  91  Figure 5.1  China's Mercury Releases Due to Mining  103  Figure 5.2  Gold Particle Size Recovery Range  108  Figure 5.3  Muller Mill / Centrifugal Concentrator, Chile  111  ,  .  ix  7  26  84  List of Abbreviations ASGM  Artisanal and Small-scale G o l d Miners  ASGMAu  China's annual gold production due to A S G M  ASM  Artisanal and Small-scale M i n i n g  AT  Appropriate Technology  BBC  British Broadcasting Corporation  BC-MEMPR  British Columbia - Ministry o f Energy, Mines and Petroleum Resources  BSAu%  The percentage o f gold produced by A S G M ball mill/sluice operations  BSR  The ratio o f mercury lost to gold recovered for ball mill/sluice operations  CF  Certainty Factor  CASM  Communities and Small-Scale M i n i n g  C A S M - C h i n a Communities and Small-Scale M i n i n g Regional Network i n China CCC  Criterion Continuous Concentration  CIA  Central Intelligence Agency  CIDA  Canadian International Development Agency  CMC  Criteria M a x i m u m Concentration  DFAIT  Department for Foreign Affairs and International Trade  DFID  Department for International Development (United Kingdom)  DoBDEF  Degree o f Belief - Dangerous Environmental Factor  DoBHEF  Degree o f Belief - H i g h Emission Factor  DoBMAF  Degree o f Belief - Mercury Adsorption Factor  ESAT  Environmentally Sound and Appropriate Technology  GM1  G o l d Mountain Feed Ore Sample  GM2  G o l d Mountain Muller M i l l Tails Sample  GM3  G o l d Mountain Cyanidation Tails Sample  GMP  Global Mercury Project  GRG  Gravity Recoverable G o l d  HgAu  The amount o f mercury released per annum due to A S G M activities  HgEX  Expert System for Risk Assessment for Mercury Discharge from G o l d M i n i n g Operations  ICP-MS  Inductively Coupled Plasma - Mass Spectrometry  IIED  International Institute o f Environment and Development  ILO  International Labour Organization  ITDG  Intermediate Technology Development Group  KC-MD3  Knelson Concentrators lab-scale M D 3 centrifugal concentrator  MMAu%  The percentage o f gold produced by A S G M operations using muller mills  MMR  The ratio o f mercury lost to gold recovered for muller mills  MMSD  M i n i n g , Minerals, and Sustainable Development  NGO  Non-Governmental Organization  NIMD  National Institute for Minamata Disease  NMAZ  National Miners' Association o f Zimbabwe  NSERC  National Science and Engineering Research Council  NRCAN  Natural Resources Canada  PBC  People's Bank o f China  PMAu%  The percentage o f gold produced by A S G M placer operations  PMR  The ratio o f mercury lost to gold recovered from placer deposits  PRC  People's Republic o f China  RMB  Renminbi (Chinese Dollar or Yuan)  SCOPE  Scientific Committee on Problems o f the Environment  SWG  Southwestern Resources  TDU  Transportable Demonstration Units  TOC  Total Organic Carbon  TVE  Township and Village Enterprises  UBC  The University o f British Columbia  UNECA  Unit o f G o l d Extraction and Controlled Amalgamation  UNIDO  United Nations Industrial Development Organization  UNDESA  United Nations Department o f Economic and Social Affairs  USEPA  United States Environmental Protection Agency  WHO  W o r l d Health Organization  YPNI  Yunnan Province Nuclear Industry Team 209  xi  Acknowledgements  Part of this research was made possible by the support of the World Business Council for Sustainable Development, through a report written for the International Institute of Environment and Development's (IIED) Mining, Minerals and Sustainable Development (MMSD) project, by the National Science and Engineering Research Council (NSERC) Industrial Postgraduate Scholarship in cooperation with Knelson Concentrators, and UBC's Bridge Program.  Special thanks to: Dr. Marcello Veiga, my primary advisor, and Dr. Bern Klein, my other primary advisor, Dr. Chris van Netten, and Dr. Yin Yongyuan, Dr. Lin Yuhuan, Dr. Shen Lei, Dr. Peter Golas, and Dr. Philip Andrews-Speed, Yue Jian, for his invaluable help and friendship, The UBC Sustainability Working Group, especially Jenn Hinton, for advice and help on finding references, Edmund Bugnosen, Anne-Marie Fleury and the MMSD group, Jon Coates with BHP Billiton in China, Ish Grewal, Linda Duncan, Jim Zhang, and Dennis Grimm at Knelson Dr. Kay Teschke and the Bridge Program, and Jeffrey Davidson and Gotthard Walser, at Communities and Small-Scale Mining (CASM).  Many thanks to others who helped me out in China, but who would rather not have their names recorded, especially the miners of "Gold Mountain."  Finally, special thanks to my wife, Melania Cannon, for all her assistance and patience.  xii  1  Introduction  This thesis determines that artisanal and small-scale gold mining ( A S G M ) in the People's Republic o f China ( P R C ) employs at least 400,000 miners extracting about 60 tonnes o f gold per annum and releases around 240 tonnes per annum o f mercury into China's environment. This thesis focuses on describing China's artisanal and small-scale gold miners, estimating their mercury releases, and exploring technological alternatives to reduce these releases.  Mercury is one o f the most toxic heavy metals, and mercury pollution has led to many tragic incidents around the world. A S G M is a major source o f global mercury releases; the health impact o f this mercury is o f significant concern, both locally and globally. This thesis grew out o f an interest to understand China's role in these releases and to learn how A S G M i n China differed from A S G M i n other regions o f the world.  1.1  Statement of Problem  A n exploratory literature review found only one article regarding A S G M in China; that article stated that most A S G M has been strictly prohibited since 1996 ( L i n et al, 1997). However, a handful o f global reviews o f A S G M prepared by multilateral agencies such as the International Labour Organization (ILO), indicated that China was home to millions of artisanal and small-scale miners. This thesis grows out o f an initial research trip to China, conducted in 2000, undertaken to examine the situation regarding A S G M in China.  Specifically, this thesis aimed to address the two following questions: 1) Does A S G M still occur in China, and i f so, at what scale and in what socioeconomic context? 2) Does A S G M in China use mercury, and i f so how much? H o w does A S G M in China use mercury, and are there methods  o f dealing with the resulting  environmental and health problems applicable to other parts o f the world, or can techniques used in other nations be applicable to China?  1  1.2  Background  Artisanal and small-scale gold mining is closely linked with the global emission of mercury. This link is o f importance on a number o f levels. Locally, A S G M mercury use is a serious health risk faced by millions o f artisanal and small-scale miners and their communities around the world. Non-mining communities located downstream from mercury-using A S G M operations are also placed at risk. O n a global level, A S G M contributes to mercury releases that may be linked to the atmospheric deposition o f mercury around the world. This section reviews artisanal and small-scale gold mining and mercury use in a global context. 1.2.1  Artisanal and Small-scale  Mining  1.2.1.1 Definition Artisanal or small-scale mining ( A S M ) is the use o f rudimentary processes to extract valuable minerals from primary and secondary ore bodies, and is characterized by the lack o f long-term mine planning/control (Hinton et al, 2003a). A S M can be illegal or legal, formal or informal and can encompass everything from individual gold-panners to large-scale operations employing thousands o f people. 1.2.1.2 Extent and Impact Artisanal and  small-scale mining operations  form the  backbone  o f hundreds of  developing rural communities around the world and supplement the income o f thousands of agricultural communities. In an authoritative I L O study on A S M , Jennings (1999) estimates that there are 11 to 13 million artisanal miners worldwide, with 80 to 100 million people directly or indirectly dependent on artisanal miners for their livelihood. A S M extracts a wide range o f metals, precious stones, and industrial minerals, and accounts for a significant portion o f world production, as can be seen i n Table 1.1.  2  Table 1.1  A S M Production o f Various Minerals and Metals (Noetstaller, 1995)  Metals  Mined by Industrial A S M (%) Minerals  Mined by A S M (%)  Beryllium Mercury Tungsten Chromium Antimony Manganese Tin Iron Lead Zinc Cobalt Gold Silver Copper  100 90 80 50 45 18 15 12 11 11 10 10 10 8  90 90 90 90 90 80 75 70 60 30 30 20 20 10  Fluorite Graphite Talc Vermiculite Pumice Feldspar Clay Gypsum Barite Sand and gravel Dimension stones Salt Coal Phosphate  1.2.1.3 Health. Safety and Environment The employment, income and production generated  from A S M often come with  significant costs to miners' and nearby communities' health, safety, and environment. A S M hazards are many and varied.  In A S M mines, hazards include: poor ground conditions leading to underground failure, methane or coal dust explosions from coal mines, flooding, machinery accidents, poor lighting and ventilation, explosives accidents, and electrocution (Priester et al, 1993). Hydraulic monitoring o f secondary deposits can also be extremely unsafe, as a potential exists to undercut h i l l slopes and generate landslides (Hinton et al, 2003a).  Mercury, cyanide and other hazardous chemicals are used as reagents for recovering and purifying gold and other precious metals. Fine dust from mineral processing, leading to silicosis,  and  noise  pollution are  endemic  problems. A S M accidents  are  often  underreported, due to the illegal or semi-legal status o f most A S M operations; Jennings  3  (1999) estimates that non-fatal accidents i n A S M are still 6-7 times greater than i n the formal mining sector.  A S M operations can also lead to the destruction o f arable and grazing land through excavation, the accelerated erosion o f top soils, landslides, the collapse o f old workings, unsafe tailings disposal, the lowering o f water tables, soil contamination due to dust from mines and tailings, and increased levels o f sediment load and flooding i n nearby rivers. 1.2.1.4 Gender and Social Issues Perhaps 30% o f the A S M miners around the world are women, involved at all stages o f mining from ore extraction to processing to market (Hinton et al, 2003b). W o m e n also frequently work part-time as cooks and service providers, or i n transporting and processing, and thus the actual number o f women involved in artisanal mining could be significantly higher than generally estimated. Processing activities are often conducted in homes by women o f childbearing age who are especially susceptible to mercury poisoning (Hinton et al, 2003a).  In addition, A S M , especially i n the boomtowns that arise from big mineral finds in remote locations, may come with major social challenges such as prostitution, substance abuse, and gambling. Women are often disproportionately harmed by these factors. The roles o f women i n A S M are significantly different from those o f men and thus deserve, but generally do not receive, special attention with regard to policy, development, and research (Hinton et al, 2003b). 1.2.1.5 Sustainable Livelihoods & Communities With the range o f i l l effects that arise from A S M , governments often see closing these often-illegal mines as a desirable end. However, A S M frequently provides impoverished remote communities with a rare opportunity to alleviate poverty and contribute to community development (Dahlberg, 1997). A l l ore deposits are finite, thus by definition no single mining operation can be sustainable. Nevertheless, A S M can contribute to the sustainable  development  o f communities by providing opportunities for economic  diversification through auxiliary enterprises, such as jewellery production and agricultural  4  development, and by providing enough economic impetus to allow impoverished communities  to  move  toward  sustainability. International  organizations,  such  as  Communities and Small-scale M i n i n g ( C A S M ) and the United Nations Department o f Economic and  Social Affairs  (DESA)  are  focusing on promoting a  sustainable  communities approach to A S M . A n underlying premise o f this thesis is that A S M must be looked at i n the context o f sustainable livelihoods and communities in order to most effectively mitigate the impact o f A S M activities while maximizing its benefits to current and future generations.  1.2.2 Mercury as a Global Pollutant Mercury is a global pollutant due to both its impact through actions such as the disposition o f atmospheric mercury i n the Arctic, and its local impact i n communities worldwide. Present concern about the health impact o f mercury can be traced back to the methylmercury poisoning disaster in Minamata, Japan, in the 1950s ( N I M D , 2001). The Minamata outbreak, followed by another incident in Niigata, Japan, both occurred due to the consumption o f large quantities o f seafood polluted by mercury-contaminated industrial effluent. Both culminated in several hundred deaths and claimed hundreds o f more victims with severe mercury induced symptoms (Harada, 1978). These cases created widespread awareness about the i l l effects o f mercury and prompted much research on the topic (Horvat, 2002).  The global importance o f mercury became increasingly evident due to a number o f further issues. Mercury-based fungicides and seed disinfectants were found to have caused severe reductions o f bird populations (Jernelov et al, 1975). In 1971-2, a large epidemic that killed over 450 people and may have disabled over 100,000 people occurred in Iraq when farmers consumed foreign aid supplied wheat, intended for seed, treated with alkyl mercury fungicide (Forstner and Wittman, 1997). Unsafe levels o f mercury accumulation were found i n fish and wildlife i n Canada, the northern United States, and Scandinavia during the 1960s (Williamson, 1986). Fish in reservoirs in Quebec and Manitoba were found to have elevated levels o f mercury, perhaps due to forest fires or organic material in newly flooded areas (Williamson, 1986; Stokes and Wren, 1987). Mercury vapour poisoning killed 15 miners, with 205 more miners admitted  5  to hospital, in a mercury mine i n Keniya, Turkey (Trakhtenberg, 1974). A report from 1992 estimated that i n the previous 40 years, over 20,000 people were afflicted by mercury poisoning, including 1,400 deaths (Larcerda, 1997).  This rising concern led to increasing efforts to understand global mercury releases and to create regulations to control its trade and use. First implemented i n the 1970s, these regulations have steadily reduced global releases o f mercury, primarily through banning mercury-based fungicides and mercury-cell chlor-alkali plants and through the recycling of mercury from solid wastes (Larcerda, 1997). The sale o f fish containing mercury levels above 0.5 mg/kg was banned i n the 1970s.  In the m i d to late 1990s, atmospheric deposition o f mercury i n the Arctic due to both natural and anthropogenic sources became an issue o f increased concern ( L u et al., 2001). Anthropogenic releases o f mercury originate primarily from: coal and o i l combustion, refuse incineration, solid and urban waste disposal, and agriculture and forestry practices. Anthropogenic releases are four times higher than natural mercury releases (Larcerda, 1997). Pacyna and Pacyna (2002) estimate that the 1995 anthropogenic global mercury emission was about 1900 tonnes, with three quarters o f the total emission coming from combustion o f fuels, particularly coal combustion i n China, India, and South and North Korea. A European Commission Report estimates the current annual market supply o f mercury at 3800 tonnes (Maxson, 2004). In the past, mercury mining has been the major source o f mercury; Hylander and M e i l i (2003) estimate around 1 million tonnes o f mercury have been mined globally since 1500.  A major source o f mercury releases has been A S G M . Maxson (2004) estimates total global mercury releases due to A S G M in 2000 to be 650 tonnes, 20% o f the total global anthropogenic amount o f 3386 tonnes. Mercury has been used to amalgamate precious metals since as early as 2,700 B C , when the Almaden mines in Spain were opened (Lacerda, 1997). Amalgamation is a simple and inexpensive method o f recovering gold. The wetting o f gold by mercury is not alloying, but a phenomenon o f moderately deep sorption, involving some interpenetration o f the two elements (Pryor, 1965). A s the  6  surface tension o f mercury is greater than that o f water, but less than that o f gold, mercury adsorbs onto the surface o f gold particles. In addition, mercury acts as a dense medium; gold sinks into the mercury while the lighter gangue material floats overtop. The solubility of gold in mercury is only 0.06% at 20°C. When the resulting amalgam is heated, the mercury vaporises, leaving gold dore.  The practice o f using mercury to extract gold had largely faded i n the early twentieth century, until the gold rushes in Latin America began during the 1970s and 1980s (Veiga, 1997). Millions o f miners flocked to sites such as Serra Pelada, where 80,000 miners produced 90 tonnes o f gold from a single pit. Veiga (1997) estimated that around 5,000 tonnes o f mercury was released into forest and urban areas i n Latin America over this time. In addition to Latin America, small-scale mining spread through areas o f Africa and the A s i a Pacific. Mercury, due to its simple effectiveness and practicality, is virtually ubiquitous with small-scale gold processing. These gold miners have been both a major source o f mercury releases and have been one o f the groups, along with nearby communities, most seriously harmed by mercury pollution.  Figure 1.1  Number o f Artisanal & Small-scale Miners Around the W o r l d by Country  7  Using  the  I L O data  from  Jennings  (1999),  Mining,  Minerals,  and  Sustainable  Development ( M M S D ) (Hentschel et al, 2002), C A S M (Davidson, 2003) and the United Nations Industrial Development Organization's ( U N I D O ) Global Mercury Project ( G M P ) (Veiga, 2004c), Figure 1.1 was compiled. Countries where estimates have not been made, but A S M is known to occur, are listed as "no estimate available." National A S M numbers were calculated as the mean o f the high and low estimate compiled from the reports. This figure does not include any countries with a GDP/capita over $ U S 15,000, with a population under 150,000, or with an area less than 4,000 square miles, in order to exclude tiny countries and recreational gold panners i n affluent countries. 1.2.3  Mercury as a Local Health Concern for  ASGM  The mercury used i n A S G M has wide effects on the miners, the local environment, and the people living downstream from A S G M operations. Exposure to mercury mainly occurs  through  inhalation o f mercury  vapour  or  through  the  consumption  of  methylmercury. Repeated exposure to mercury eventually leads to progressively more serious health problems. 1.2.3.1 Mercury Vapour Elemental mercury vapour is rapidly absorbed through the lungs (Keating et al, 1997). The people most affected by mercury vapour are the artisanal miners who practice amalgamation, and the gold shop workers, where the gold dore is bought and purified. Amalgam typically consists o f about 60% gold and 40% mercury, with varying amounts of silver. Miners often purify their amalgam into dore by either directly evaporating mercury on a stovetop or by open flame. This method can lead to serious mercury vapour poisoning. A n alternative is to use a retort to distil the amalgam into dore while safely collecting and condensing the mercury vapour. Artisanal gold miners frequently purify their dore at gold shops, or at home. This process releases the 2 - 5 % mercury remaining in the dore into the gold shop and thus into the town environment. People living near the mining operations or the gold shops are also affected; the majority o f mercury emitted by gold smelters is deposited near the emission source (i.e. within 1 km), contaminating the local areas (Veiga, 1997).  8  M a l m (1991) measured up to 60,000 u.g/m o f mercury in the air when amalgam was 3  burnt in pans; the recommended limit for public exposure is 1.0 u g / m ( M a l m et al, 1990) 3  and the recommended health-based exposure limit for metallic mercury is 25 ug/m for 3  long-term exposure and 500 ug/m  for short-term exposure ( W H O , 1991). When retorts  are used, mercury vapor concentration drops to as low as 10 u g / m (Veiga and Baker, 3  2004), much lower than the 50 ug/m limit for industrial exposure outlined in the Health, Safety and Reclamation Code for Mines i n British Columbia ( B C - M E M P R , 1992).  Mercury vapour is oxidized i n the lungs and forms mercury complexes that are soluble in many body fluids (Veiga and Baker, 2004). While around 90% o f the inhaled mercury is excreted through urine and feces in a few days (Hacon, 1990; W H O , 1991), some o f the mercury accumulates  i n the  central nervous  system (Mitra,  1986). Mercury can  permanently damage the nervous system - the kidneys are most affected i n the mediumterm, while the brain is the dominant receptor i n long-term exposure (Suzuki, 1979). Total mercury elimination through urine can take several years (Veiga and Baker, 2004).  High, short-term exposure (1000 to 44,000 ug/m ) to mercury vapour is typically associated  with  symptoms  including chest  pains, dyspnoea,  cough,  haemoptysis,  impairment o f pulmonary function, and interstitial pneumonitis. Chronic exposure symptoms include a metallic taste i n the mouth, gum diseases such as gingivitis, ulcers and the formation o f a blue line at gum margins (Stopford, 1979). Long-term, low-level mercury vapour exposure  has resulted i n less pronounced  symptoms o f fatigue,  irritability, loss o f memory, v i v i d dreams, and depression. Long-term exposure to high levels o f mercury vapour can lead to delirium, hallucinations and suicidal tendency as well as erethism (abnormal irritability), excessive shyness, insomnia, and in some cases muscular tremors. In milder cases, erethism and tremors regress slowly over a period o f years following removal from exposure pathways ( W H O , 1991).  A person with a m i l d case o f mercury poisoning can be unaware o f the symptoms because they are mainly psycho-pathological. The symptoms can also be confused with fever, alcoholism, or malaria and other tropical diseases.  9  1.2.3.2 Methvlmercurv Methylmercury exposure is a primary source o f mercury uptake for humans and wildlife; methylmercury is easily bioaccumulated and becomes concentrated in fish, particularly in carnivorous fish. Carnivorous species are usually the preferred species o f consumption by most people and represent the main exposure pathway o f methylmercury to humans (Veiga and Baker, 2004). Methylmercury (CH3Hg ), an organic compound, is the most +  dangerous form o f mercury, as it is easily absorbed through the gastrointestinal tract (Keating et al, 1997). When mercury from artisanal mining (or any other source) is released into water systems, it may react with organic acids and thus be oxidized into methylmercury (Hinton, 2002). This methylmercury is bioavailable, which means it can quickly find its way into the food chain. It can also easily bioaccumulate, or build up over time i n an organism's body, and thus methylmercury concentrates at the top o f the food chain, i n fish and then i n humans (Horvat et al, 2000). Around 70 to 90% o f the mercury in fish is already i n the form o f methylmercury, which rapidly reaches levels where excessive consumption by humans can be dangerous.  Carnivorous fish are  most  susceptible to bioaccumulation as they eat a large amount o f omnivorous or herbivorous fish, and retain most o f the mercury that those fish have accumulated. In fish, methylmercury can impair reproduction, growth and development, lead to behavioural abnormalities, and lead to death. Mercury can also harm plants, birds, and mammals, with reproduction also being effected (Keating et al, 1997).  Mercury-laden mine tailings have been linked with higher levels o f methylmercury (Baker, 2002). While not o f the magnitude o f Minamata, fishing communities near A S G M operations have been found to exhibit symptoms o f methylmercury poisoning, especially along the Tapajos River i n Brazil (Grandjean et al, 1999; Harada et al, 2001; Mergler, 2002).  However, the actual mechanisms that convert metallic mercury to methylmercury are complex and not fully understood. Variables such as sediment E h (standard hydrogen electrode potential), p H , conductivity (uS/cm), total organic carbon ( T O C ) , and sulphate, all contribute to this transformation (Veiga and Baker, 2004). The other variables  10  identified which contribute to methylation include the supply of Hg(II), composition of micro-organisms, temperature, biomass, and iron (Hinton, 2002). Variables able to reduce mercury availability include the presence of hydrous ferric oxides, the presence of clay sediments, and suspended solids (Veiga and Meech, 1995). Figure 1.2 shows an Eh-pH diagram for the main inorganic mercury species.  Eh (volts) 2  i  1 r 2+  1.5 water oxidized  -0.5  Figure 1.2  Eh (redox potential) versus p H for the Main Inorganic Mercury Species (Meech etal, 1998).  It is important to note that there is a wide variety of possible sources of mercury other than A S G M , including geologic weathering and erosion, evaporation from waters and soils, run-off  waters, ancient gold and silver mining, plant transpiration and  decomposition, waste incineration, and forest fires (Veiga and Baker, 2004). Camourze et al (2001) highlighted the importance of erosion in carrying natural mercury bound to intensively weathered soils to Amazonian aquatic systems. The authors stressed that this is a much more important source of mercury for the entire Amazonian environment than any other source, although A S G M activities are more relevant locally.  11  People with severe methylmercury poisoning, or "Minamata Disease" exhibit all of the following five symptoms: visual constriction, numbness of the extremities, impairment of hearing, impairment of speech, and impairment of gait. Muscular atrophy and mental disturbance are prominent in acute intoxication (Veiga and Baker, 2004). Unborn children are especially susceptible to methylmercury poisoning. Methylmercury can penetrate into the placental barrier, transferring mercury to the foetus. When the intake of mercury is large enough, sterility can occur in both women and men. When the dosage is smaller in women, pregnancy can take place but the foetus can miscarry spontaneously. Even when the pregnancy goes to term, the baby can have severe neurological symptoms, including psychomotor retardation and other developmental delays (Harada, 1978).  1.3  Outline of Thesis  Chapter one has provided a background review of artisanal and small-scale gold mining and mercury pollution, in order to underlie the following examination of China's A S G M sector. The chapter introduced mercury as a global health threat, summarized the toxic nature of mercury vapour poisoning and methylmercury accumulation, and defined and summarized A S G M globally and its link to mercury pollution. In addition, it here outlines the structure of this thesis and its overall objective.  Chapter Two describes the objective, methodology and results of a general study of China's A S G M industry and communities. At the time this research was undertaken, little research had been done to understand the nature of China's A S G M and its relationship to mercury since the early 1990s, and none had been done since mercury was made illegal in 1996. The objective of this stage of the research was to examine several A S G M sites throughout China to evaluate whether A S G M still took place and under what conditions and if mercury use persisted and represented a potential health threat. A discussion explores the A S G M sector in China in detail, including estimates of the number of gold miners and production figures, basic laws and structures, and socio-economic situations.  Chapter Three is devoted to a case study of "Gold Mountain", a small A S G M community in northern China. This study was undertaken to elaborate and verify the findings of the  12  general study described i n Chapter T w o . It describes the community, surveys its gold processing facilities, describes i n detail its gold processing methods, estimates mercury losses, and describes a novel mercury retort used locally.  Chapter Four describes the objective, methodology and results o f test work undertaken on three " G o l d Mountain" samples. These samples include a feed ore, an intermediate tailing sample from amalgamation process, and a final tailings sample following amalgamation and cyanidation. The objectives o f the test work are the following: to verify the mercury losses reported in Chapter Three; to evaluate the potential o f centrifugal concentrators, in conjunction  with  cyanidation,  to  replace  the  current  amalgamation/cyanidation  techniques; and to explore the effect o f cyanidation o f mercury tailings on mercury solubility.  Chapter Five brings together the results o f the previous chapters to estimate the extent o f mercury released by A S G M in China. In addition, potential technology alternatives to amalgamation that could reduce those releases are discussed and issues surrounding alternative technology and technology transfer are examined.  Chapter Six discusses the limitations and bias o f the thesis.  Chapter Seven identifies areas that would benefit from additional study.  Chapter Eight concludes the thesis by highlighting the key results and by discussing recommendations for how the impact o f mercury releases from A S G M can be mitigated.  The Appendix contains a report  o f the  inaugural meeting o f C A S M - C h i n a ,  an  organization formed i n part to address the issues raised i n this thesis.  13  2  S t u d y O n e : A r t i s a n a l & Small-scale G o l d M i n i n g i n C h i n a  2.1  Introduction  As stated in Chapter One, the objective of the research described in this chapter is to examine several A S G M sites throughout China to evaluate whether A S G M was still taking place and under what conditions, and if mercury use persisted and represented a potential health threat. The basis of this research was a field study undertaken during the summer of 2000. The research focused on understanding the use of mercury by A S G M miners and seeing if their methods of dealing with these environmental and health problems could be applicable to other parts of the world, or if techniques developed outside of the PRC could be used by the Chinese.  The summer 2000 field study resulted in site visits to six regions, investigating seven mineral processing operations, three underground mines, one gold shop, one dredge operation, and one mine prospect. This survey resulted in a number of small case studies, future contacts, and a sense of how the A S G M industry operated in China, and provided the basis for further research. The trip demonstrated that A S G M and mercury use were common and widespread throughout China.  Interviews were also conducted with a variety of experts involved with A S G M in China in different capacities. These interviews, combined with the literature review and site visits, form the basis of the discussion section of this Chapter, an exploration of the place of A S G M in China.  2.1.1  Literature Review  The sum total of the literature available before the summer 2000 field study was one article: Lin, Guo, and Gan's Mercury Pollution From Small Gold Mines in China (1997). This article gave a brief overview of China's A S G M industry and a case study description of A S G M in Dexing County, Jiangxi Province. In 1993-4, Dexing had 200  14  "roll mills", probably muller mills, which each used around 8 k g o f mercury per day, o f which 10-20% was lost to the environment. Extensive use o f mercury was recorded, with losses in Dexing reaching 160-320 kg o f mercury per day. If it is assumed that the mines ran for 300 days per annum, 48 to 96 tonnes o f mercury were released annually from Dexing County alone. O f four articles in the bibliography, two refer to American mercury guidelines and the other two refer to a difficult-to-find Chinese journal (Environment & Exploitation). The article also makes reference to a S C O P E C h i n a / C A S T study in 19931994. This study is perhaps altogether lost, but is certainly unattainable. L i n et al conclude their article with the following statement: "Since September 1996, most of the small scale gold mining activities strictly  prohibited  investigation  by  China's  national  environmental  legislation.  in late 1996 indicated all those small mines [researched]  were Recent  were shut  off (Lin et al, 1997). " Interestingly, the site visit i n 2000 found a larger operation than described by L i n et al (1997) and amalgamation was still clearly integrated into their processes. The most valuable item from literature review, however, was L i n et al's (1997) simple sketch o f China that indicated areas with small-scale gold mining. This map formed the basis for the field study.  Some visiting Chinese professors to the U B C mining department declared there to be no artisanal mining in China and certainly no A S G M mercury use (Veiga, 2000). Thus, when the field study was undertaken, there was no indication that A S G M  operations  existed i n China or continued to use mercury.  Other works include Golas's excellent history o f mining in China (1999), which provided a great background, but provided little help for a study on contemporary China. Lacerda (1997) includes some erroneous information on China's A S G M in an article on global mercury releases. For example, he reports, "after granting permission to form individual  1  The muller in muller mills is not capitalized - muller comes from an alteration of the Middle English term  molour and means "a stone or piece of wood, metal, or glass used as a pestle for pounding or grinding (Merriam-Webster, 2004)."  15  enterprises i n China, over 200 small mines were opened i n D i x i n g Province since 1992, increasing gold production by 10% per year." Larcerda was presumably reporting on the 200 A S G M operations i n Dexing County, Jiangxi Province, recorded i n L i n et al, 1997 (China does not have a D i x i n g Province). Larcerda also reports, "Major  [mercury]  impacts are from the Brazilian Amazon, followed by China, where over 200 small gold mining operations  were settled and  120 t/yr o f H g are being released into the  environment." Again, these were, the releases from one county among thousands in China, and are hardly a national figure. These errors demonstrate the importance o f field research to aid i n understanding a large and complex country.  Since the first field study, a handful o f other articles relating to A S G M in China have appeared. These include "Mercury consumption and contamination o f environment in gold mining in China" by He, L i n , and L i (2000). He et al (2000) estimated China's mercury consumption to be only 80 tonnes per annum, but did so from estimates o f 33 smaller state-owned mines, not by visiting A S G M operations. He et al estimated that 13%  o f gold production was from amalgamation, with 33 mines losing 14.6 g  mercury/tonne, with 75% recovered and recycled, leaving 20 tonnes/a discharged. This can be taken as a reasonable estimate o f the amount o f mercury released by China's formal mining sector, but not its A S G M industry.  Dai et al's (2003) article on mercury releases from small gold mines i n Tongguan County, Shanxi Province notes how gold has been mined for over 900 years i n Tongguan, and that most families i n the County are involved in gold mining. A n unpublished 1997 report from L i n Yuhuan is cited, stating that around 120 tonnes o f mercury are released in the county annually; 38% into the atmosphere, 62% into the tailings, and less than 1% into the local rivers. D a i et al (2003) report their findings o f water sample mercury concentrations, with dissolved mercury ranging from 0.11 to 3.10jj,g/l (average o f 0.74ug/l) and particulate mercury levels ranging from 0.10 to 258.62 ug/1. In filtered water, reactive mercury ranged from 7.76 to 62.28% o f total mercury. D a i e r al (2003) do not report on the amalgamation processes used.  16  An unpublished paper given by Zhong (1999) at the Small-and Medium-Scale Mining Workshop of the 3 Environmental Cooperation Workshop on Sustainable Development rd  of Mining Activities in 1999 detailed the small-scale mining industry in China. Zhong provided an overview of ASM in China and explained the importance of ASM to local development and environmental and safety issues arising from ASM activities. While the paper mainly focused on coal, it did provide some excellent information on new policies affecting ASGM. Zhong made no reference to mercury releases.  A 2001 report by Canada's Department for Foreign Affairs and International Trade (DFAIT), provides some useful statistics on ASM  (although incorrectly sourced), but  little else.  An extensive review undertaken for the MMSD ASM country report for China (Gunson and Yue, 2001) found a broader review of artisanal and small-scale mining in China yielded applicable laws, journal articles, books, statistical yearbooks, and newspaper reports. There was one book and twelve articles on ASM coalmines, primarily on safety and closure. With respect to mercury, there were three articles on coal combustion and mercury, and three short general articles on mercury in China (primarily coal and industrial sources of emission). There were twelve news articles on small-scale coal disasters (these were a sample - there are many more such small news reports, generally reporting the location and the number of dead miners), nine on a Guangxi ASM tin mine disaster, and one article on a labour protest. Eight laws and regulation guidelines were found to be relevant to ASM, and three general reports on China's mining industry included small sections on ASM. For an industry that directly employs 3 to 15 million people in China and has a major economic and environmental impact on the world's most populous nation, this is a shockingly understudied area.  Since 2000, a handful of additional articles on ASM coal policy have been written by Andrews-Speed in cooperation with Chinese academics (2002, 2003a, 2003b, 2003c). These articles, while specific to coal, have implications for the ASGM sector, discussed in later sections.  17  2.2  Methodology  In order to achieve the f i e l d study objectives, several A S G M sites and the a m a l g a m a t i o n practices u t i l i z e d at the sites were e x a m i n e d throughout C h i n a . T h r e e m a i n techniques were used: •  Site v i s i t s ;  •  P e r s o n a l i n t e r v i e w s w i t h p e o p l e associated w i t h A S G M ; and  •  T h e H g E X E x p e r t system.  2.2.1 Site Visits T a b l e 2.1  Area  Site V i s i t s , 2000-2002  Year 2000  "Gold Mountain"  2000  Longsheng County  One G o l d Dredge, One G o l d Shop  Jiangxi Province, South Central China  2000  Leping County  One G o l d Processing Plant  Jiangxi Province,  2000  Dexing County  One G o l d M i n e & Processing Plant  2000  Tongling County  One Canadian Junior Joint Venture  2000  Bayuan, Qingling  T w o G o l d Processing Plants.  North-Central China Guangxi Province,  County  Sites Visited 2  O n e g o l d m i n e , one m i n e prospect, and three p r o c e s s i n g plants  South C h i n a  South Central China A n h u i Province,  c o p p e r - g o l d - s i l v e r p r o c e s s i n g plant.  Central C h i n a Shaanxi Province, West Central C h i n a North-Central  Mountains  2001  "Gold Mountain"  One gold mine, two gold processing plants, one z i n c / A u s m e l t i n g  China  operation, t w o i r o n p r o c e s s i n g plants, t w o f i s h i n g reservoirs Inner M o n g o l i a  2001  Baotou Municipality  North-Central  2002  "Gold Mountain"  M i d - s i z e d State O w n e d G o l d M i n e w i t h centrifuges.  China  Processing Plant, Placer G o l d Operation, Sand and Gravel A S M operation.  Site v i s i t s were undertaken to research institutes i n B e i j i n g a n d A S G M areas i n H e b e i , G u a n g x i , J i a n g x i , A n h u i , a n d Inner M o n g o l i a p r o v i n c e s , c o v e r i n g northern,  2  southern,  Gold Mountain is a pseudonym. While the miners have local government permits to operate, they are  concerned about receiving publicity for fear that higher levels of government will shut them down.  18  south-central, and western China. Table 2.1 describes the site visits made, including visits to six counties, in these five provinces. Sites were chosen from the map included in L i n et al (1997), a small note found i n Atiyah et al (1997) and discussions with a wide variety of people. Once i n an. area known to have A S G M , locals were queried as to exact locations o f mines and processing operations. U p o n arriving at a mine, processing site, or gold shop, a manager or operator would be asked for an interview and a tour.  2.2.2 Interviews Over 25 interviews were conducted at A S G M mines, mills, and villages with labourers, operators, managers, financiers, retired miners, woman miners or wives o f miners, fishermen, and local government officials. Interpreters were used when appropriate, or necessary, and were available at all times except for the first site visit to " G o l d Mountain" and the site visits to Guangxi and Inner Mongolia. Over the course o f the site visits, and especially during interviews, miners were observed for any signs o f mercury-related illnesses, such as muscular tremors or gingivitis.  A t A S G M mine and process sites, people interviewed were generally asked the following questions: •  H o w long has the mine been operating?  •  H o w did the operation get started? What permits are required to operate?  •  Is the operation legal?  •  H o w many employees are there?  •  What is the mine ownership structure?  •  H o w many other gold mines/processing plants are i n the area?  •  What tonnage is usually processed per hour?  •  What are the average gold grades and your general gold recovery?  •  What is the mine or process operation?  •  Is mercury used in the operation? H o w ? Is the mercury use legal?  •  Are they aware that mercury can be dangerous to their health and environment?  •  Where did they get their mining equipment and how much did it cost?  •  Where did they learn their techniques?  19  •  What is their relationship with the government and how do they pay tax?  •  What is their relationship with local environmental agencies?  In addition, over 15 people from research institutes, government offices and embassies, formal and international mining companies, and multilateral agencies were interviewed. These interviews were conducted in ASGM areas, Beijing and other major centres in China, and internationally. Questions were asked about: •  The political, social and environmental situation of artisanal miners in China, including their legal status;  •  The land-use conflicts and coexistence between artisanal miners and the largely agriculture-based communities of rural China;  •  The traditional mining concept and the current public perception of mining in China; and  •  The relationship between artisanal miners and international mining companies.  These last interviews were necessary to develop a broad understanding of ASGM in China. 2.2.3 HgEX Expert System During the initial field research, Veiga and Meech's "Expert System for Risk Assessment for Mercury Discharge from Gold Mining Operations", or HgEX (1996), was extensively used. Conventional approaches that attempt to correlate natural variables with mercury biota levels have relied on empirical regression models that often yield poor bioaccumulation predictions (Hakanson et al, 1988). Predictions are fraught with uncertainties and unknowns such as internal correlations between variables and sitespecific aspects of biota contamination. HgEX uses a heuristic approach in which mining and amalgamation methods, along with natural variables, are dealt with using inference equations to give varying degrees of belief about the risk of bioaccumulation. The system can handle uncertain or vague data using fuzzy logic and neural network techniques. These procedures were intended to reduce the need for extensive monitoring programs and provide a preliminary diagnosis about bioaccumulation risk (Veiga and Meech, 1992). Despite sparse data and uncertainty, a diagnosis can still be made about the likelihood of a critical situation. HgEX was developed to make risk assessments of 20  mercury discharge from small-scale gold mining operations, primarily in the A m a z o n region by integrating information on biology, chemistry, geochemistry, and medical, social and political issues in order to evaluate mercury contamination for a single site or region (Veiga and Meech, 1996).  i 100  low 0  medium -  Technical  Process is rejected  •  \  high 100 Process is accepted  Figure 2.1 Alpha Factor for H g E X (Veiga and Meech, 1996) A s the behaviour o f workers depends on societal incentives and reactions, the definition of the level o f acceptable mercury releases w i l l differ with the values o f the society. T o map these differences, an alpha factor is calculated based on socio-political, technical and economic aspects o f a society which relate to the acceptance or rejection o f mercury use in gold mining operations. A high alpha factor indicates acceptance o f amalgamation practice and low control o f mercury releases enforced by a society, which may be a country, a region or a city. For many regions in Africa, Latin America and A s i a , a = 1; however, for Canada, where mercury is practically banned and well monitored by authorities, the alpha factor is much lower (0.1 or 0.01). For Canada 150 years ago, when the hazardous effects o f mercury were unknown and thousand o f miners were colonizing the West, the alpha factor would have been much higher (about 10 or 100). Thus the  21  alpha factor can adapt H g E X ' s conclusions on high emission levels to different countries' or regions' conditions (See Figure 2.1).  H g E X integrates common-sense knowledge with observations and field samples o f variables that usually correlate positively with mercury pollution. B y accepting vague data and by estimating the importance o f variables, H g E X enables the evaluation and recording o f mercury use and its potential effects i n situations where a lack o f funds and equipment would otherwise prohibit study.  2.3  Results  2.3.1  Site Visits — Gold Processing Equipment and Methods in  China  This section describes the gold processing methods observed during the site visits. The primary methods observed include muller mills, ball mill/sluices, and dredges. Secondary processes observed include cyanidation, retorts, and dore purification. 2.3.1.1 Muller M i l l s Muller mills were found at sites in " G o l d Mountain" and Shaanxi. Muller mills, also known as edge. mills or Chilean mills, simultaneously grind and amalgamate  ore,  kneading fine gold into the mercury. The mills usually consist o f two or three large cast iron or stone wheels rotating on a central axis around a circular metal trough (see Figure 2.2). The wheels were approximately one metre in diameter. A l l muller mills observed were powered using electric motors, although it would be feasible to drive them with combustion engines or even animal power. A l l but the most remote areas o f China are electrified, so electrical power is usually not a problem. Priester et al (1993) state that the mills require five to seven kilowatts o f power to run, although a stronger motor is sometime required to start the wheels rolling.  Ore is crushed to roughly minus one inch and then shovelled into the m i l l . A t least one kilogram o f mercury is added per tonne o f ore and ground together between the wheels and the trough. L i m e is added to reduce mercury flouring and to raise the p H for cyanidation. Liberated gold contacts the mercury and forms amalgam, which can easily be collected by stopping the m i l l and cleaning the trough at least once a day. The 22  overflow fines are collected and leached with cyanide to further recover gold. The mills can process around one tonne o f ore per hour, grinding the ore to approximately 80% mass passing 200 um.  Figure 2.2  " G o l d Mountain" Muller M i l l  Locally manufactured muller mills are inexpensive, costing approximately US$1200. The muller wheels need to be replaced periodically and chips o f iron continuously fall off and need to be removed from the mercury, during cleaning, usually with magnets. A s the muller wheels each weigh at least a tonne, having local sources o f production is practical to minimize transportation costs.  In the " G o l d Mountain" region a muller m i l l manufacturer claimed to have sold over 500 mills locally. " G o l d Mountain" miners stated that they had taken the technology to areas in Inner Mongolia and to have exported the technology to areas as far as Myanmar, and that the technology was apparently introduced from Russia. In Shaanxi, a woman who used to mine explained that the muller m i l l technology was common in the area and had  23  been imported into the region by miners from Henan Province. Muller mills seem to be the technology o f choice for A S G M in northern China.  The ratio o f mercury lost to gold recovered (Hgi :Au oduced) is a common method for ost  pr  evaluating mercury losses from small-scale mining (Veiga, 1997; Hinton et al, 2003a). The ratio for muller mills varies greatly, as miners change the amount o f mercury added based on their estimate o f the gold grade and size distribution in their ore. Estimates of the Hgiost:Aup oduced ratio run from about 10:1 to 50:1. This is explored in greater detail in r  Chapter 3. 2.3.1.2 Ball M i l l / S l u i c e Two operations in Jiangxi Province, two in "Gold Mountain", and one in Shaanxi Province were observed using a ball mill / sluice box method. The ore is crushed by a jaw crusher and then passes to a hopper feeding the ball mill. The electric-powered ball mills observed were around 1.5 to 2 metres in diameter and about three metres long. Oversized "pebbles" are collected from the ball mill discharge screen and returned to the feed. The ball mill discharges onto a sluice box with a mercury-coated plastic carpet or copper amalgamation plate before flowing to a spiral classifier that returns the coarse material to the ball mill (Figure 2.3). The fines from the classifier continue on to flotation and/or cyanidation processes. The carpet or plate is cleaned at least daily to collect the amalgam. These plants process in the range of 30 to 100 tonnes o f ore per day. A s night shifts were uncommon, this likely meant 10-hour days processing 3 to 10 tonnes per hour. Ball mills typically use around 12 k W per tonne of ore, varying greatly with the ore's hardness (Priester  etal, 1993).  Miners in Jiangxi stated that they bought their mills from equipment manufacturers in Shandong Province and that other operations in the area used the same technology. Two larger mills in "Gold Mountain" were observed using similar unit operations, but did not use mercury at the time o f the visit. A larger mill temporarily closed in Shaanxi Province, which appeared to use this technology and this type o f operation, is identical to the 72 operations described in He et al (2000). Thus, this method seems common for slightly  24  larger A S G M operations. These types o f mills are built as a package by equipment manufacturers and installed with some technical instructions.  Figure 2.3  Jiangxi B a l l - M i l l Mercury Sluice Circuit  Jiangxi miners claimed to process 30 tonnes o f ore per day and to lose one kilogram o f mercury per day. Getting accurate gold grades from miners was difficult, but assuming a generous amalgamation recovery o f 10 grams/tonne, this would lead to a Hgi st:Au oduced 0  pr  ratio o f 3.3:1. 2.3.1.3 G o l d Dredges and Placer M i n i n g Over 10% o f China's gold reserves are in placer deposits (Zhou and Goldfarb, 2002). One gold dredge visited i n Guangxi Province shared its section o f river with at least four other gold dredges. The dredge consisted o f a line o f heavy iron buckets attached to a digging arm  inclined between two pontoons, with a small superstructure holding everything  together (Figure 2.4).  25  Figure 2.4  Guangxi Gravel/Gold Dredge Operation  Each bucket could hold about two cubic feet o f material, and the dredge probably moved less than 30 cubic yards per hour. The buckets discharged the river gravel onto a screen, separating the coarse stones from fine gravel. The fines passed over a simple sluice box with a plastic carpet to catch the gold. Both the fine and coarse material was deposited into small barges and then transported to shore. The sluice box was cleaned every day or two, and they usually recovered around one or two grams o f gold with each cleaning, although they could recover up to six or seven grams i n some richer areas o f the river. However, these dredges were primarily recovering gravel for China's huge aggregates industry.  The  Guangxi dredge  operation  amalgamated  and  panned  their  sluice  concentrates on the side o f the river. From international experience, amalgamation o f concentrates without retorts have Hgi :Auproduced ratios o f around 1:1 (Veiga, 1997). ost  In 2002 a return trip to " G o l d Mountain" found a new gravel operation, using a front-end loader, screens, and a carpet sluice (Figure 2.5). The sluice was cleaned at least once a day and all o f the heavies retained were passed over a shaking table. They claimed not to  26  use mercury to recover gold from the concentrates; however, they did use mercury at their muller mill operation.  Figure 2.5  Gold Mountain" Gravel/Gold Operation  Over the course of this research, dozens of similar dredges and gravel operations have been observed all over China. It would be logical to assume that many of these also attempt to recover gold. 2.3.1.4 Retorts  Retorts were observed in Dexing and Leping in Jiangxi Province, and "Gold Mountain". The Dexing and Leping retorts consisted of two parts: a cast iron pot and a lid device. A metal tube, approximately three feet long, was attached to the top of the removable lid. Around a foot away from the lid, a water coolant tube encircled the lid tube. Amalgam is placed in the pot and the lid is sealed. Heat is applied to the pot and the mercury in the amalgam evaporates, and escapes the chamber through the tube. As the mercury gas passes through the water-cooled section of the tube, the vapour condenses and drips out the end of the tube, to be collected and recycled (Figure 2.6). In "Gold Mountain", miners used an innovative retorting method, heating amalgam in a bowl covered by a bucket sealed with water. This retort will be discussed in detail in Chapter 3.  27  Figure 2.6  Jiangxi Province Retort Cooling Tube  2.3.1.5 Cyanidation & Zinc Strip Smelting ASGM  leaching operations were observed  in four processing centres in "Gold  Mountain", in Inner Mongolia, and in Leping and Dexing in Jiangxi Province. In Bayuan in Shaanxi, miners sell their tailings to larger mills for cyanidation. Gold ore, often after amalgamation and/or flotation, is placed in vats in the range of 200 cubic feet. The tank is saturated with a leach solution, and the pregnant solution is drained out the bottom of the tank. The leaching time depends primarily on the type of gold ore; refractory gold ores could be leached for as long as a week. Cyanide concentrations vary widely with the type of ore.  The unfiltered pregnant solution drains out the bottom of the tank and flows through locked metal boxes filled with fine zinc strips (Figure 2.7). Gold replaces the zinc through the Merrill-Crowe Process; periodically, the boxes are cleaned out, the zinc strips collected, and smelted to recover the gold. The solution is not aerated before cyanidation or de-aerated afterwards, leading to lower gold dissolution and recoveries.  28  Figure 2.7  " G o l d Mountain" Zinc Strip Boxes  Slightly larger state-owned gold mines use activated charcoal in leach methods with stirred tanks to recover gold. These operations frequently cannot compete with the A S G M private processing operations. 2.3.1.6 G o l d Shops G o l d shops were only visited i n Guangxi and " G o l d Mountain", but can be found all over China. Inquartation, or 'quartering,' is undertaken to purify the gold. Silver is first added to ensure a gold-to-silver ratio o f roughly 1:4. Then the silver and any remaining mercury are dissolved with nitric acid over a hot plate at l o w temperatures, usually out-of-doors with no fume hood, close to the miners' home. Nitric acid w i l l not dissolve the silver i f the silver ratio is too low. G o l d is left as a brownish powder.  To further purify the gold a cupellation process is used. Miners melt lead into the gold and place the gold-lead solid inside a concrete ball, which is then baked on a coal barbeque. The lead and other impurities are absorbed into the concrete leaving behind a relatively pure gold bead. Usually cupels are made o f magnesite or bone ash; the use o f  29  concrete for cupellation is uncommon. The gold is sold to local consumers or the government, usually at world market prices.  Figure 2.8  2.3.2  Burning Dore in Longsheng  Interviews  The results o f the site visit interviews are integrated with the results o f the site visit observations,  i n Section 2.3.1. In general, people interviewed were friendly and  informative. More than a few o f the site visits were followed up with a shared meal and a few drinks. These informal events often provided an excellent opportunity to gain the trust o f the miners and to learn from them in a less threatening environment.  During the initial site visits and interviews, no overt signs o f mercury related illnesses were observed, such as gingivitis and muscular tremors, often used as potential indicators of advanced mercury poisoning. Less pronounced symptoms such as fatigue, irritability, loss o f memory, and depression would have been impossible to detect by an observer  30  with no medical training during short site visits and interviews. However, in the subsequent case study i n " G o l d Mountain", one miner with severe mercury-related illness was interviewed, as described i n Section 3.3.3.1.  The results o f the interviews with people from research institutes, government offices and embassies, formal and international mining companies, and multilateral agencies are integrated into Sections 2.3.3 and 2.4. Where possible, the interview results  are  corroborated with references.  2.3.3  HgEX Expert System  H g E X was an invaluable tool during the initial research, as it provided detailed explanations o f the primary factors o f mercury releases from A S G M and o f mercury bioaccumulation. It also provided an excellent set o f questions and areas to investigate, which made the preliminary research far more effective than it would have been otherwise. In this section a determination o f China's national alpha factor is presented, along with an evaluation o f mercury contamination for the site o f Bayuan, Shaanxi Province. 2.3.3.1 A l p h a Factor Determination for China The national or regional alpha factor is one o f the primary determinants o f H g E X . The result o f an alpha factor determination for China is shown below. H g E X questions are in italics and the certainty factor (CF) is noted i n brackets at the end o f the responses. " Y e s " equals 100% C F and "no" equals 0 % C F .  Is it easy to evade laws that control Hg usage? Mercury laws were in place i n China ( L i n et al, 1997) and miners indicated they were aware o f them i n interviews. In Jiangxi Province and " G o l d Mountain" it seemed relatively easy to get a locally issued permit to use mercury, although higher levels o f government did not recognize these permits. Mercury regulations were  sometimes  enforced. In Bayuan a month before the site visit in July 2000, the Shaanxi Provincial Environmental Agency fined and shut down all operations using mercury. Everywhere visited was cautious about provincial environmental agencies. (50% C F )  31  Is there any incentive provided by the government for informal mining  operations?  Interviews indicated there were not currently any incentives. In the 1980s to early 1990s the government did encourage A S G M (Andrews-Speed et al, 2003c), but since 1995-97 the  government  has  cracked  down  heavily.  However,  local  governments  do  encourage/work-with/own-a-stake-in some o f the mines, as A S G M is frequently vital to providing employment and taxes to local economies. (10% C F )  Frequently  Hg pollution  affects other social groups, such as fishermen,  natives, urban  people, etc. not directly involved with mining activities. Do the groups, which may be affected by Hg pollution,  have political  power?  Downstream urban communities wield significant power i n China, and are generally the driving force behind environmental concern. N o areas visited had significant w i l d fish stocks, but aquaculture was common and fishermen would have some power. "Natives," or minority groups i n China, usually had some "autonomous" power over the counties they resided in, which would give them a significant amount o f power. However, this would also mean they were probably a major force in local mining, although this does not seem to be the case i n Tibet (World Tibet Network News, 1995) However, i n poor regions local government would give precedence to A S G M . (90% C F )  Many societies hold a mystique that gold mines are an easy way to get rich. Is this an important point in this society? Perhaps, however with so many sectors o f the economy booming in China, this is only one o f many options, and this is probably less o f a factor than i n other A S G M areas o f the world. Miners interviewed considered mining more profitable than farming, but starting a business or moving to an urban area would be considered more profitable than mining. (50% C F )  Is mining a traditional occupation in this society? M i n i n g probably has a longer continuous history in China that anywhere else in the world, and is certainly is a traditional occupation. Historically mining, as with other  32  commercial activities, was looked down upon by Chinese society (Golas, 1999). Regardless, mining is new to some communities, and was new to the Bayuan site. (100% CF)  Is the level of education high in this society? In the cities, the education level is high. In the areas where the mines are, the mine operators usually have about the equivalent o f high school education, but much o f this might have been received during the Cultural Revolution, when the education system was in turmoil. Virtually everybody would have been in school for between six and nine years. However, functional illiteracy is a big problem i n rural China, mainly due to the difficulty o f mastering Chinese writing. Officially the overall literacy rate in China is 86% (CIA, 2003); however, 90% o f the illiterate 14% o f the population is located in rural areas (People's Daily, 2002c). (80% C F )  Is the interaction between miners and other educated people (university level) frequent? In the 1980s to early 1990s such interaction was more common (Zhang, 2002). In the early 2000s, much o f the mining and process techniques  came from  equipment  manufacturers, who presumably have access to university-educated people. The caution exhibited by A S G M operators toward environmental agencies indicates there was some interaction, and the environmental agencies presumably had some access to universityeducated personnel. While some operations would interact, the vast majority would not interact frequently. (30% C F )  Is the dominant media reliable and well While  the  informed?  Chinese media is censored  politically,  it increasingly comments  on  environmental problems (People's Daily, 2000, 2002a, 2002b). The press tries to report on A S M disasters, but local operators and officials are often uncooperative. (40% C F )  Are ecological groups active? There are many international groups with local cooperation on issues such as soil erosion in northern China, and urban environmental health issues. There are not any domestic  33  environmental N G O s with significant power (United States Embassy i n Beijing, 2001). (20% C F )  Is amalgamation the first option considered by miners to extract gold? Yes, all o f the A S G M mines visited used amalgamation. Cyanidation is another common option, in addition to gravity and flotation. (100% C F )  Is mercury readily available to miners? Yes, mercury was readily commercially available and inexpensive (US$ 6 - 8.50/kg). China has had a large mercury mining industry, which probably supplied most o f the mercury. China also had A S M mercury mines, which may have been i n the mercury supply chain. In addition, mercury is imported into China both directly and through Hong K o n g (Maxson, 2004). (100% C F )  Gold placers, colluvium, laterite deposits and abandoned tailings are usually  neglected  by companies due to low grade. Are miners currently working these types of deposits? Most A S G M operations visited were working small, high-grade quartz veins. N o miners were observed reprocessing tailings. Some gold dredges were observed, but only as part of  aggregate  operations.  Reports  from  Canadian junior  exploration  companies  (Southwestern Resources, 2004) indicate that A S G M miners often mine on potentially large deposits. (20% C F )  Do miners make frequent improvements recovery and reduce mercury  in the amalgamation process to increase gold  emission?  A l l operations would greatly vary the amount o f mercury used depending on the quality of ore they were using. While miners visited tinkered significantly with their reagents, they tended to hold with the equipment available. (50% C F )  Is it easy to introduce new gold extraction technologies? (Miners can assimilate The  easily?)  small-scale state owned mines did not seem very flexible, and i n interviews  managers stated they could not compete with the A S G M private operations, which were  34  generally run like small businesses. If a product could be shown to increase the revenue or reduce their costs, the private miners would be extremely interested. (50% C F )  Are miners aware of the side effects of mercury? A l l o f the miners and people interviewed were aware mercury is dangerous. However, the specifics o f mercury contamination were not necessarily well understood. (70% C F )  Do the miners have access to any specialized technical support? The miners i n Dexing were in contact with a company i n Shandong Province that made mining equipment and provided some specialized technical training; i n addition, they used government exploration teams to find their mines. Experienced miners from Henan Province trained the miners i n Bayuan. However, these sorts o f contacts were erratic and not available to all operations. (60% C F )  Have the government or other research  institutions  come out with alternatives  or  solutions for mercury use? In the 1980s and 1990s, there was some assistance and research. The prevalence o f retorts suggests some involvement. However, since the A S G M crackdown, it doesn't appear like there has been much interaction. (60% C F )  Are miners currently working ores in which gold recovery from concentrate is low when amalgamation  is used?  A S M operators were extremely discreet with gold recovery figures. Most operations visited used multi-stage recovery, following amalgamation with flotation and/or leaching. Miners claimed to recover 30-70% o f their gold with mercury methods. (20% C F )  Is it easy to set up a monitoring programme  to survey mercury pollution extent?  To set up an effective, nationwide monitoring program would be prohibitively difficult and expensive due to the size o f China. However, local or regional surveys are possible, in close cooperation with Chinese agencies or organizations ( L i n et al, 1997; D a i et al, 2003). (30% C F )  35  Are there any examples of spectacular gold discoveries (or rushes)? Around 2001, gold was found in the B o k a area i n Yunnan Province. In the period o f a couple o f years over 50 tunnels were put into operation. Similar discoveries are probably made regularly, but are not significant in a country the size o f China. In the early 1990s there was a gold rush in western China (Tse, 1996), and up to 10,000 miners rushed to the Nagqu area i n Tibet in 1994 (World Tibet Network News, 1995). However, all the site visit mines were operated by local Chinese, and these gold rushes do not appear to have been on the scale o f the gold rushes in Latin America (40% C F ) .  Is mining activity important for the region's economy? In most o f the areas visited, mining was clearly the dominant industry. In China as a whole, it is quite important, but is superseded by agriculture, manufacturing and commerce (China State Statistical Bureau, 2000). (80% C F )  Agriculture  represents the main activity in some regions, but the quest for land leads  individuals to see mining as an alternative. Is this the case for this society? A S G M is certainly seen as an alternative to the poor returns o f agriculture i n rugged, remote areas. However, better alternatives exist in China's booming coastal economy. M i n e owners/managers are largely local business people, seeking a high return on their capital. Labourers often seek to supplement their agricultural income. (80% C F )  Is the mercury price high compared with the international market (US$ 4/kg)? The price was as low as U S $ 5.50/kg in 2001. (0% C F )  Does mercury represent a high cost in the mining  operation?  Since the cost o f mercury was so low and the ore was usually high-grade quartz veins, mercury was a minor cost (See section 3.3.1.6). (0% C F )  Do the mining operations require expensive equipment? (High investment?)  36  Most o f the mines had a significant investment in equipment (crushers, ball mills, muller mills, or dredges). However, these items are usually made locally for little cost, and some operations were l o w tech (Bayuan in particular). (30% C F )  Is the region experiencing economic  difficult economic times and is mining seen as a feasible  alternative?  China has boomed for the last 20 years; however, most o f the development has occurred in the eastern coastal areas. A S G M areas are often far from the coast or large cities, and have had significantly less economic growth. M i n i n g , along with migration to the cities, or small-scale rural industries is among the feasible alternatives. (50% C F )  Is the minimum wage low? In some o f these areas, U S $ 300 or 400 would be an average annual wage. (100% C F )  Is inflation low? In the early-to-mid 1990s, there was significant inflation, up to around 20%/year. However, since 1997, inflation has not been significant and some prices have even dropped. (100% C F )  High Acceptance  Low Acceptance  100  0.01  North America Today  China, Brazil Today  Figure 2.9  North America in 1800s  A l p h a Factor Comparison  These answers led to an A l p h a Factor for China o f 1.00, indicating that China has a moderate acceptance o f amalgamation practices. A s shown in Figure 2.9, this factor is  37  similar to that o f Brazil i n 1994 (Veiga and Meech, 1996). This A l p h a Factor was used as input for the site evaluate for Bayuan described below. 2.3.3.2 Bayuan Site Contamination Bayuan, Shaanxi Province, is presented as a case study for a local diagnosis (Gunson et al, 2001). Southeast o f X i ' a n , a major interior city and ancient capital o f imperial China, lie the Qingling Mountains, home to hundreds o f A S G M operations. A local Bayuan woman, who had once owned and managed an A S G M processing centre, provided most of the information about the area. One month before the Bayuan field study, the X i ' a n government environmental agency had shut down and fined a number o f mines in the area due to non-compliance with environmental laws. It was assumed that the mines would soon reopen, as is frequently the case in China.  This valley had four state owned mines and over ten privately owned mines. The private mines mainly used locally manufactured muller mills to amalgamate whole ore and used a sluice box to recover amalgam. A past A S G M operator stated that amalgam was frequently burned openly without retorts, and the m i l l tailings drained into pits. These tailings were sometimes sold to the state mines for reprocessing, but otherwise they were piled nearby, which allowed the runoff to drain into the local stream. The Qingling Mountains are full o f other small valleys similar to Bayuan.  H g E X accumulated data input through its heuristic method, accepting uncertain or vague information. Using fuzzy logic and neural network techniques, H g E X output  the  following bioaccumulation assessment:  This is a small site in which milling is the predominant amalgamation  extraction method. The  process is typically applied to whole ores, using muller pans.  Amalgam is separated from heavy minerals in excavated pools or simply panned at  creek  margins.  watercourse, amalgam  Amalgamation  tailings  are  left in pools or sold for reprocessing.  is burned directly  in a pan.  either  discharged  into  the  Retorts are not used as the  The sediment has a background  level  38  inferred by HgEX at 0.042 ppm mercury. The water colour of the main drainage 3  is clear and the biomass is low. Hot spots were visually identified, indicating a high mercury level. The contaminated sediment is rich in gravel and grey in colour. Near the mining activity, the watercourses are clear. Based on the above information, using a weighted inference equation, H g E X calculated a diagnosis by determining the following factors: •  The local mercury releases were estimated to be very high, with a Degree o f Belief H i g h Emission Factor ( D o B H E F ) o f 90%. This factor is based on evidence about whether high releases o f mercury are occurring locally, such as the use o f muller mills;  •  The natural conditions were estimated to be slightly dangerous, with a Degree o f Belief - Dangerous Environmental Factor ( D o B D E F ) o f 39%. This factor was based on indicators such as water colour and the presence o f local hotspots;  •  The adsorption process was slightly possible, with a Degree o f Belief - Mercury Adsorption Factor ( D o B M A F ) o f 20%, based on indicators such as suspended solids and sediment colour; and  •  The overall risk o f bioaccumulation was determined to be high, with a Degree o f Belief - Potential Bioaccumulation Risk o f 100%, based on the equation D o B H E F + DoBDEF - DoBMAF.  The summary generated by the input data was as follows:  Mining activities are emitting very high mercury levels into the aquatic environment in which natural conditions are slightly dangerous for methylation and bioaccumulation. Mercury adsorption by sediments is slightly possible to control bioavailability. This situation leads us to believe that the risk of increasing mercury levels in the biota is high.  3  Please note that HgEX has not been validated for China. These results are estimates only.  39  Finally, the H g E X output stated that retorts should be introduced at local mine sites.  2.4  Discussion -  ASGM in  China  The site visits and interviews, i n conjunction with the  HgEX  expert  program,  conclusively determined that A S G M still took place in China i n the early 2000s, and that mercury use was widespread and represented a significant health threat.  The following discussion integrates the results o f the interviews about the general state o f A S G M i n China with the information gathered from site visits and interviews, H g E X , and the findings o f the literature review. This broad overview highlights important differences between A S G M i n China and other nations and is necessary i n order to understand the present state o f A S G M i n China and how the sector can become less damaging and more sustainable in the future. 2.4.1  Significance  of ASM  in China  Unlike most developing countries, gold extraction is not the main A S M activity in China. China has the largest mining industry i n the world, by number o f mines, production, or employees. China's A S M miners make up the vast majorities o f China's mines, approximately half o f the employees, two fifths o f the production, and around a quarter o f the value o f production ( D F A I T , 2001). M i n i n g is a significant economic activity in all o f China's provinces, municipalities, and territories, with the exception o f Shanghai. It has been an important driver o f China's booming economy and is one o f the largest sources of pollution in China.  China's A S M industry employs at least six million artisanal miners (Gunson and Veiga, 2004), composing about half o f the artisanal miners i n the world (Jennings, 1999) and constituting one o f the largest sectors o f the mining industry worldwide. They produce at least 11 per cent o f the world's coal output, easily out-producing the entire coal industry of major producers like Australia or India. A s shown i n Table 2.2, China is one o f the largest producers o f metals and minerals i n the world, topping the world in antimony, coal, iron, lead, manganese, tin, tungsten and zinc (Billiton, 1999); artisanal miners produce at least 30 per cent o f each o f these minerals ( D F A I T , 2001). Table 2.2 does not  40  provide a complete accounting Chinese A S M , but highlights selected minerals. The chief economist o f R i o Tinto, one o f the largest mining companies i n the world, states it "is difficult to overstate the importance o f China to the future o f the world mining and metals industries" (Humphreys, 2002). China is unique in the scale and diversity o f its artisanal mining industry.  Table 2.2 Mineral Product  Aluminium Antimony Coal Copper, mined Gold Iron Ore Lead, mined Manganese Mercury Molybdenum Phosphate Rock Salt Tin, mined Tungsten, mined Zinc, mine 4  2.4.2  Chinese Productions o f Several Major Minerals (after Billiton, 1999 and D F A ]IT, 2001) % Produced Number of China's China's Production ASM World by Chinese in 1997 ('000 Ranking by ASM workers tonnes) Production 10 75.63 23,625 8,000 101 1 46.44 54,599 1,360,000 1 42.58 2,696,056 54,865 440 8 9.08 0.185 5 33.3 463,000 259,704 1 32.13 249,000 1 31.13 83,827 650 1 65.77 74,170 2,300 8.52 738 0.614 3 11,364 2 15.46 30 45,145 30,400 2 51.03 2 10.36 3,188 29,300 31,906 1 44.48 56 1 35.31 25,599 24 83,827 1 31.13 1,210  Scale of ASGM in China  2.4.2.1 Definition China has few completely illegal or unregistered miners, primarily because it is relatively easy to get some sort o f permit from the local government. Zhong (1999) estimates that only 10% o f A S M had no legal status in 1999. However, reliable statistics estimating the number o f illegal miners are simply not available, given the nature o f illegal mines and  4  The gold figures are based on the discussion in section 2.4.2.2.  41  the scale o f A S G M over a vast area. Undoubtedly the number o f illegal mines varies widely from region to region.  Most artisanal and small-scale mining in China today can be categorized as Township and Village Enterprises ( T V E ) . The concept o f the T V E is a flexible organizational model that was developed to handle the dismantling o f the commune system as China began to implement economic reforms i n the late 1970s. T V E s were intended to "promote economic growth and to absorb the surplus rural labour force and discourage excessive urban migration" (ILO, 1998).  T V E s have since come to dominate China's rural  economy, employing up to 120 million workers, and producing billions o f dollars o f goods including everything from toys to coal. They are also covered extensively in China's statistics, and thus present an easy target to use to define small mining.  TVEs  are hybrid institutions, commonly an ambiguous  alliance between  private  entrepreneurs and local government officials acting as "owners". The entrepreneurs, or managers, negotiate contracts containing both implicit and explicit conditions for them to conduct their business with the relevant public officials. Managers can gain a great deal of flexibility in such contracts and the local officials secure revenue for their local government (or for themselves). Officials often also provide special access to inputs, public resources, tax breaks, or any number o f other incentives to help their local T V E s . The local Peoples' Congress elects these officials, so many T V E s are inherently political institutions.  The term T V E officially means an organization owned or financed by a township or village government. For the purpose o f collecting statistics, the term has been expanded to include collectively and individually owned enterprises, including self-employed people, i f they are officially registered and are run by people from rural areas, defined as farmers, or peasants. A s T V E s are by definition in rural areas, T V E s once fell under the responsibility o f the Ministry o f Agriculture, but are now under the Ministry o f Land and Resources. The distribution o f T V E ownership varies widely between regions. In  42  practice, local governments interpret what constitutes a T V E based on local conditions (ILO, 1998).  While the T V E category covers most A S M mines i n China, there are exceptions. Some T V E mines are large enough, and perhaps sophisticated enough, to raise the question o f whether they are actually artisanal or small-scale mines. There are privately owned small mines that may not be registered as T V E s , as well as an indeterminable number o f outright illegal mines. Furthermore, a few o f the state-owned mines, which are considered large-scale, are actually quite small and/or primitive. Mines owned by the federal, provincial, or prefecture (municipal) governments are often considered to be state-owned, or formal mines, whereas mines at a county, township or village level are generally T V E s . In addition, a range o f state companies and agencies own A S M operations, including the army, the prison service and large-scale mining companies (Andrews-Speed et al, 2003b).  Private mines, while financed by private individuals, often have at least some connections to local government. These mines are usually licensed, but only with locally issued licenses that are often just a formality. Anywhere from one to several businessmen w i l l often create a small formal company with ownership divided into shares based on the initial contributions. Profits are then split accordingly. These partnerships are sometimes referred to as collectives, but the labourers usually do not have a share i n the partnership. The company w i l l use local prospectors or hire a professional geological team to find a deposit, or w i l l already have a deposit in mind. One or two o f the businessmen w i l l manage the mine. In practice, these managers have considerable control o f the mine finances and may often be seen as not splitting profits fairly.  In the late 1990s, the central government turned over control o f most o f its artisanal mines to provincial and prefecture governments, in an effort to concentrate on larger mines. These state-owned small mines tend to follow the law much more closely than the other small mines, and often have a better safety and environmental record than others.  43  Worker cooperatives do not seem common. Equally absent are producer associations; individual small mines rarely formally cooperate with each other i n associations, although the owners are often on good terms with the other mines i n the area and occasionally discuss technical issues. 2.4.2.2 Scale o f A S G M i n China  Figure 2.10 A S G M Areas Across China (after L i n et al, 1997) There are no published national figures estimating the numbers o f small-scale gold miners in China or the amount o f gold they produce. Estimates can only be inferred from other data. According to a D F A I T report (2001), i n 1997, an estimated 3,000 A S M gold mines employed well over 150,000. In comparison, i n 1994 the Chinese government estimated that 300,000 illegal entities were involved in A S G M (Tse, 1995). In another almost certain underestimate, Tse (2001) reports that in 2000, "about 1,000 gold mines were in China, most o f which were small and processed ores with obsolete technology 44  that damaged the environment and wasted resources." Zhou et al (2002) clarify this number, stating that i n addition to the 1,000 small gold mines, there are "numerous very small local mines (treating <25 t rock per day) that are not accounted for in government statistics." For context, in the North China Craton, with approximately 20% o f China's gold reserves, around 900 gold deposits and occurrences are known (Hart et al, 2002). Site visits in the area would indicate that the vast majority o f these would have at least one, and probably several, A S G M operations in production. A s seen i n Figure 2.10, A S G M activities occur throughout China. Clearly, it is difficult to get accurate statistics on the number o f A S G M operations or on the number o f people who work at them.  The problem relates back to the difficulty o f estimating China's gold production. Until 2001, China required that all gold produced be sold to the People's Bank o f China ( P B C ) , the central bank, at a fixed rate, usually around 10% below the international price. The price o f gold was changed to roughly match international prices i n 1999 (Tse, 2000), and a free gold market was established in 2001. Until 2001, China's gold production was listed as the amount o f gold purchased by the People's Bank o f China (Tse, 1997). However, most o f the gold mined by illegal miners is not sold to the People's Bank, so the total gold production was significantly underestimated.  G o l d was sold illegally for several reasons: •  Higher prices could be received (if only by smuggling);  •  M u c h o f the gold was consumed locally for jewellery; and,  •  Chinese individuals could not legally own gold as an investment until 2002. A s a hedge against China's currency, wealthy people would purchase gold.  A n indication o f the extent o f this illegal trade was seen i n 1997, when for a short time China's official gold price was held above international prices, due to the plummeting o f the international gold price. A s much as 300 tonnes o f gold was smuggled into China from Hong K o n g alone during this period (Tse, 1998).  From 1990 to 2001, China's gold production has increased from roughly 100 tonnes/year to 185 tonnes/year (Tse, 1996, 2002). There is a discrepancy between Chinese official  45  gold production numbers and outside experts' numbers, although it has been shrinking in the past five years. In 1994, Chinese official figures state that 90.2 tonnes o f gold were mined, and that 82 tonnes were purchased by the P B C . Independent experts estimate that around 132 tonnes o f gold were produced (Tse, 1995). B y the government's own figures, around 10% o f China's gold production was being sold illegally. However, extrapolated from the experts' estimate, around 40% o f gold was being sold illegally. From figures available for 1994 and 1996 this adds up to 50 tonnes and 65 tonnes sold illegally respectively.  A S G M gold production estimates rest on two main factors; how much o f the gold sold legally in China is from A S G M and how much additional illegal production occurs. L i n et al (1997) estimate A S G M produced one-third o f China's gold production o f 105 tonnes for 1995; however, Tse (2000) reports that the 1995 gold production was 140 tonnes. L i n et a/'s (1997) assumption is probably an underestimate. Zhou et al (2002) state that "local governments and rural Chinese companies now play a more important role and are responsible for 45 and 38% o f China's annual gold production, respectively." Probably none o f these operations, accounting for a total o f 83%, could reasonably be considered formal large-scale mines as understood in North America. The largest gold mine i n China produces about 3 tonnes o f gold per annum, far less than major international gold mines. China's gold production for 2001 was approximately 185 tonnes (Tse, 2002). Using a conservative estimate o f one-third o f production, this would lead to over 61 tonnes o f gold produced by A S G M .  Veiga (1997) noted a correlation between gold production and the number o f gold miners in South America. He found that the number o f miners per kilogram o f gold mined ranged from 2 to 8. The more gold a country produced, the higher the ratio o f miners required, perhaps because a higher number o f gold miners were lured by gold rushes. In rural China, the cost o f labour is very low, with mine labourers in the wealthier coastal provinces being paid from U S $ 70 to 100 per month, and in poorer regions far less. Thus, the ratio o f miners per kilogram o f gold mined is unlikely to be at the lower end. If Brazil's ratio o f 7.5 is used, the number o f artisanal and small-scale gold miners in China  46  would be as high as 463,000. This is not unreasonable, given the extremely high numbers of rural unemployment and underemployment i n China. Generating rural employment is arguably the highest priority o f the Chinese government (The Economist, 2002).  This estimate can be verified using a simple model extrapolated from " G o l d Mountain's" experience. There, one muller mill/cyanidation operation processes around 10 tonnes o f ore, recovering around 90% o f the 20 g/t feed ore, and employs around 10 people for at least 150 days a year. About 10 small mines feed the operation, each employing around 20 people. The 210 employees at the process centre and the mines thus produce approximately 27 kg o f gold per annum. In other words, 7.8 miners are required to produce one kg o f gold. This ratio leads to a national total o f 474,000 A S G M miners, quite close to the estimate indicated above. While this model is grossly simplified, similar numbers were observed i n other areas during the site visits throughout China.  2.4.3  Economic Impact of ASGM  2.4.3.1 National Impact Chinese A S M as a whole had an immense short-term positive impact on China's economy. The annual production o f China's entire A S M industry's value is in the range of U S $ 26 billion to $180 billion (Ministry o f Agriculture, 2000), significantly more than Canada's entire mining and mineral processing industry's output o f U S D $ 12.5 billion in 2001 ( N R C A N , 2002).  5  It has employed millions o f surplus rural labourers, people who  may otherwise have added further pressure to the tens o f millions o f workers migrating from rural China to its booming coastal cities.  A S G M operations often mine small deposits that would not be economical for the largescale mining sector to develop. However, A S G M can waste deposits that could be viable for more efficient large-scale mining. In addition, small-scale miners can encroach on the formal large-scale mines, and can cause great harm to the workings, by inadvertently flooding them. A S G M often high-grades a deposit, only taking the easy-to-reach, most  5  Canada's output excludes oil and natural gas, but includes coal, and is calculated at an exchange rate of  1.55 Canadian dollars to one US dollar, the Bank of Canada's exchange rate average for 2001.  47  valuable parts o f the ore body. For example, in 1995 an estimated 30,000 "peasant prospectors" in the H o i X i i area o f Qinghai Autonomous Region caused the government to close all gold mines in the area i n an attempt to protect gold reserves (Reuters, 1995). •2.4.3.2 Local Impact Locally, A S G M mines often supply the bulk o f tax revenue and employment for poor and remote counties. This revenue is largely used to pay for infrastructure, health and education, and reduces or eliminates the need for higher levels o f government to provide support. The economic impact o f A S G M is most felt in poverty-stricken, remote, agriculturally poor provinces like Guizhou. In contrast, i n a booming coastal province such as Shandong, the importance o f A S G M is more localized and relatively minor. 2.4.3.3 Impact on Formal M i n i n g Companies Most foreign and state-owned mining company officials met i n the process o f this research could give examples o f problems with artisanal miners. It is a sensitive issue; few people want to go on record on the topic and there is very little documentation. A n indication o f the animosity that exists between A S G M and larger mines can be seen from the complaints that arise. Chinese officials and state-owned companies, and Canadian junior exploration companies, frequently complain that A S G M  destroys  otherwise  valuable deposits. A S G M often takes only 20-30% o f the deposit, leaving the remaining ore less attractive to formal mining operations (United States Embassy i n Beijing, 1996).  In general, artisanal miners, despite warnings and evictions, often repeatedly illegally mine on property licensed to larger companies, usually high-grading deposits. This can make conventional mining more dangerous, less profitable and, i n extreme cases, not viable. O n the other hand, larger companies often become interested i n a site because o f the presence o f the artisanal miners. Larger companies bring i n police to force the smallscale miners off the property. Occasionally these removal operations can be quite volatile. Often the artisanal miners are migrant workers, and are forced to return to their home areas. Local miners might be given compensation i f a larger company decides to develop their property, and sometimes the larger company finds alternative areas for these miners  48  to work. These other areas may or may not be economically viable for the artisanal miners (Gunson and Y u e , 2001).  Southwestern  Resources  ( S W G ) , a Canadian junior, has an especially interesting  relationship with small-scale miners. In 2002 S W G formed a joint venture company with China Yunnan Province Nuclear Industry Team 209 ( Y P N I ) to develop the B o k a property (Southwestern Resources, 2004). Y P N I ' s name is a holdover from the planned economy days when exploration companies had mandates to explore for specific minerals to the exclusion o f all others.  Figure 2.11 A S G M Tunnels, Boka, China (Southwestern Resources, 2004) Y P N I had acquired a property called Boka, on the banks o f the upper reaches o f the Yangtze River, that the provincial exploration teams had indicated had gold, and started small-scale mining i n early 2001. In 1999 or 1998, "illegal" small-scale miners had already heard o f this assessment and started to mine the area heavily, building more than 200 tunnels into the mineralized zone, as shown in Figure 2.11 (Southwestern Resources, 2004). W i t h the signing o f the joint venture, Y P N I had the "illegal" miners evicted,  49  probably by local police forces. The "illegal" miners had permits from local governments, but the local government did not have the authority to issue such permits (Paterson, 2003). Following the removal o f the A S G M  miners, the joint venture  conducted  extensive geological surveys o f A S G M adits, or tunnels. Based on assays from samples collected from the tunnels, the joint venture announced the discovery o f a massive gold deposit and S W G stock rose almost 12 times above its value at the start o f the year. The joint venture undertook a large geological drilling program to delineate the deposit in 2003 (Southwestern Resources, 2004). N o compensation was offered to the small-scale miners, although several were hired to be on the local exploration team (Paterson, 2003). Y P N I did not stop small-scale mining operations until January 2004 (Southwestern Resources, 2004). 2.4.4  Legal  Framework  2.4.4.1 Government Framework China's hierarchical government structure consists o f 5 to 6 basic levels: National, Provincial, Municipal or Prefecture, County, Township, and Villages. While this may seem excessive, it is worth recognizing that many o f the provinces are o f similar population and size to major European nations. China is not a federal system - lower levels are directly subordinate to higher levels. In practice, however, these different levels of government often have conflicting interests and goals.  Over the past few years China has also undergone massive government institutional changes (Gunson and Y u e , 2001). After being shuffled from the Ministry o f Agriculture, A S G M now falls under the auspices o f the Ministry o f Land and Resources. 2.4.4.2 Government Policy From the late 1970s to the mid-1990s, essentially all levels o f government supported the rapid growth o f artisanal and small-scale mining (Andrews-Speed et al, 2003b). For example, A S M coal mines were given various subsidies and tax allowances. While there was consensus on the need to increase production, there was no such consensus on anything else, such as health, safety and the environment. Production grew at a prodigious rate but legal, technical, environmental, and safety requirements seemed to be  50  ignored i n most mining areas. Short-lived and half-hearted rectification campaigns failed to make any significant impact on the behaviour o f miners or local governments (Andrews-Speed et al, 2003a).  Since the late 1990s there has been little i n the way o f support for artisanal miners i n China. L i n et al (1997) reported a crackdown on A S G M i n 1996. Zhong (1999) outlined a series o f government orders to curb small-scale mining that included: •  The N o . 6 Order o f the Minister o f the State Commission o f Economy and Trade on the Catalog o f the Existing Lagged Production, Techniques and Products that must be Banned; and,  •  Catalog o f Curbing Unnecessary Repetition o f Capital Construction Investment in the Industrial and Commercial Circles.  The "Catalog o f Curbing Unnecessary Repetition o f Capital Construction Investment in the Industrial and Commercial Circles" banned approval o f or investment i n cyanide operations treating less than 10 tonnes per day o f gold concentrate, pyrometallurgial projects treating less than 50 tonnes o f gold concentrates per day, heap leaching projects treating less than 5000 tonnes per day, hard rock gold mining projects treating less than 25 tonnes per day and placer operations treating less than 200,000 cubic metres per day. A s it is difficult for many A S G M operations to achieve these tonnages, many are forced to become illegal. 2.4.4.3 Laws and Enforcement A S M i n China is subject to a large and continuously growing and changing body o f legal documents drawn up by various government agencies at all levels o f government. This regulatory framework is characterized by "duplication, inconsistency and omission" and A S M operations would be hard-pressed to comply with them all (Andrews-Speed, 2003b). Furthermore, much o f the framework is unsuited to A S M .  A few examples o f laws and regulations that apply to Chinese A S M include:  51  •  Regulations for Registering to Explore For Mineral Resources Using the Block System, 1998  •  Regulations for Registering to M i n e Mineral Resources, 1998  •  Regulations for Transferring Exploration Rights and M i n i n g Rights, 1998  •  Construction L a w o f the People's Republic o f China, 1997  •  L a w o f the People's Republic o f China on Safety in Mines, 1992  •  Regulations on Prohibition o f C h i l d Labour, 1991  •  Regulations on Reporting and Handling Fatal Accidents o f Workers and Employees i n Enterprises, 1991  •  Mineral Resources L a w o f the People's Republic o f China, 1986.  Enforcement can be both erratic and harsh. Government agencies wield significant power over mines and other small industrial operations and are often regarded as corrupt and insensitive to local needs. In August 1994, Shandong Province, China's largest gold producing province, reportedly closed down 641 illegal gold mines and 50 retailing and processing shops (Tse, 1995). O n the border o f Henan and Shanxi Provinces, 430 illegal gold mines were closed, employing 13,000 A S G M  miners, and 9,000 pieces of  equipment were confiscated. In Tongguan County, Shaanxi, 87 ore processing mills were shut down (Tse, 1997). Judging from China's record with A S M coal shutdowns, many o f these operations probably restarted.  China's environmental control agencies  can occasionally be effective. In Beijing  municipality, miners apparently use only gravity concentration for gold production. Over the 1990s, the spread o f knowledge about mercury pollution and retorts may be due to these institutions.  In spite o f the array o f laws effecting A S G M , operators are often not particularly concerned about legal consequences; they can usually bribe their way out o f trouble at the local level. Managers interviewed in Jiangxi Province stated that it is easy to get all o f the necessary local permits by hosting banquets for local government officials. In contrast, going through official routes is time consuming and costly. Enforcement o f safety  52  regulations is lax, and in the event o f casualties, management is only expected to pay the family around US$2,415 (Fong, 2001). In any case, the concept o f a legal society and regulatory framework as understood in North America is rather new to the People's Republic o f China; most o f the laws are only a decade or so old and they often mean less and less the further one gets from Beijing. 2.4.4.4 Tax A s A S G M mines are essentially regulated by hundreds o f small, local governments, which often own mines themselves, tax collection is anything but uniform. Rural tax collection is a contentious issue in China, characterized by violence and tax revolts, and unofficial taxes imposed by local governments (Pomfret, 2001). In theory, all mines are subjected to taxes, royalties, and other, often arbitrary, fees. Taxes include a 1.18% Resource Compensation Tax, a Resource Tax, and a Normal Business (or income) Tax. Royalties are collected locally for the central government, and about half o f this money is redistributed at the county level. The received royalties are used for promoting exploration and technical/safety support to the mines as well as for local government administration. Counties may not receive disbursements i n proportion to the royalties they collect; thus, there is not much incentive to collect these royalties, especially as the local governments often own the mines. Overall, the tax burden i n rural China is relatively low, but ad-hoc fees imposed by local governments can be high, often reaching 20%  o f post-tax profits (The Economist, 2002). However, the overall tax burden o f  A S G M , including ad-hoc fees, is unknown and almost certainly varies significantly with location. 2.4.4.5 Illegal A S G M According to Tse (1996), most o f the illegal A S G M operations are found in western China, i n Gansu, Guizhou, Ningxia, Shaanxi, Sichuan, Qinghai, Xinjiang, Xizang, Yunnan.  L i n et al (1997) reported that most o f the alluvial gold deposits are mainly  exploited by individuals and that around half o f the hard rock gold operations are mined by individuals or collective units. Tse (1996) describes the illegal operations as such:  53  Scrambling  to get rich, hundreds or perhaps thousands of gold hunters rushed to  the west. Widespread illegal exploration and unregulated gold mining  seriously  damaged the environment in the region. Government authorities were concerned that the country's already degraded base of natural resources was also being depleted. Most of the mined gold was traded illegally.  To keep things in perspective, most "illegal" A S G M operations researched had local permits, paid local taxes, and boosted remote rural economies. They were known and, at some level, permitted to operate by at least county level government officials. The miners were primarily small entrepreneurs trying to escape the extreme poverty o f farming a small plot o f marginal land. They were illegal primarily because o f the lack o f effective laws and regulations suitable for A S G M .  2.4.5 Social Context: ASGM in the Community A S G M has a host o f impacts on communities in China. Foremost is the employment and income A S G M brings to rural areas. The China State Statistical Bureau (2000) states that the average number o f dependants per rural labourer is 1.54. Based on the estimate o f 463,000 miners, this would lead to over 700,000 dependants. However, the I L O estimates that the number o f people who depend on A S M , including a small multiplier effect, is approximately 7.5 dependants per miner (Jennings, 1999). Using this factor, the number of people dependant on A S G M i n China would rise to 3,470,000 people. 2.4.5.1 A S G M Labourers Artisanal mine labourers in China are categorized as farmers (peasants), but usually spend most o f their time and derive most o f their income from mining. A l l rural workers, in theory, have some farmland available. The mines visited shut down for periods o f approximately ten days around planting and harvest time. One problem that arises from these workers' status as farmers is that when the government or companies shut down artisanal mining operations, they do not concern themselves with the labourers, as they can "just return to their farms." However, many o f these farms do not provide enough income to support a family, which is why many o f the farmers begin mining in the first place.  54  Artisanal miners are occasionally migrants from poorer areas o f China and bring all the problems usually associated with migrant workers, including prostitution and violence. This may be a particular problem with miners moving into ethnically distinct regions like Yunnan and Tibet (World Tibet Network News, 1995). 2.4.5.2 A S G M Income The typical salary for mine labourers i n eastern China i n 2001 was between six and eight hundred Renminbi ( R M B ) per month (1 U S $ = 8.28 R M B ) , or about 8400 R M B per annum (US$ 1014). Miners stated that this was roughly similar to other labour jobs, but that mines had paid much better even a few years previously. In comparison, the average Chinese mining engineer at a visited state-owned mine makes 27,000 R M B per annum (US$ 3260), and the average annual income per capita in rural China is 2210 R M B per annum (US$ 267), although this varies widely from region to region (China State Statistical Bureau, 2000). M i n e owners are often quite wealthy, and are capable o f investing hundreds o f thousands o f R M B i n a new project. The owners are usually businessmen who may be involved i n several types o f industry. Their private businesses are often incredibly flexible, and demand quick payback o f their investments. Arguably, the business skills learned by these A S G M mine managers and owners offer the best chance for sustainable development for these communities, as mines are closed down or run out o f ore. 2.4.5.3 W o m e n According  to  the  "Regulations on Labour Protection for  Employees" (State Council, 1988), "It is forbidden employees to work in underground  mines."  Female  to assign female  Workers  and  workers  and  W o m e n are usually not directly involved  with the ore extraction or mineral processing i n Chinese A S G M , but they are often on mine sites assisting with cooking and other aspects o f daily life. In " G o l d Mountain", some o f the wives o f A S G M owners were active in business affairs. The woman interviewed i n Bayuan, Shaanxi, had been directly involved with processing gold ore, but she had insisted that her husband sell their processing centre and she bought a small store with the proceeds. She claimed she did not want to raise her children while operating a  55  mine. There may be hundreds o f other such cases but women do not seem to be a significant source o f labour. D r . Peter Golas, from the University o f Denver, spent considerable time traveling to various A S G M sites, while writing the "Science and Civilisation i n C h i n a " history o f mining. Golas  (2003) concurred that women and  children did not seem to be a large part o f the labour force. In contrast, at a larger stateowned mine visited i n Inner Mongolia about a third o f the employees, including engineers, were women. 2.4.5.4 Children In a l l but the most impoverished and remote areas o f China, children usually attend school. Legally, children are prohibited from working until age sixteen (State Council, 1991). Miners interviewed i n " G o l d Mountain" believed that some underage boys worked in coal mines i n the next municipality. One report indicates that 10% o f the artisanal gold miners i n Nagqu, Tibet, were under the age o f 14 (World Tibet Network News, 1995). However, i n part because o f the one-child policy, there are perhaps fewer children involved than i n other countries. It is uncommon for rural families to have more than two or three children. Since such labour is illegal, there are no official statistics on its extent. Regardless, child labour does not seem to be prevalent in China's A S G M industry. 2.4.5.5 Labour Unions China has only one union; the state controlled and sanctioned A l l China Federation o f Trade Unions and its branches. A n y unofficial unions, informal worker groups and attempts to form labour groups are illegal. The state union has little power to bring employers to account, and "given its status as a government sanctioned body i n many cases, union leadership corresponds to factory management  (China Labour Bulletin,  2003)." This was confirmed during site visits. Private A S G M operations visited did not have organized labour. 2.4.6  Health, Safety, and Environmental  Impact  The negative impacts o f artisanal mining i n China on health, safety, and the environment are huge and difficult to quantify. Many villages have found themselves enriched at the expense o f their health and environment. A S G M is far less deadly than China's A S M coal industry, which kills 4,000-6,000 miners every year (State Bureau o f Coal Industry, 56  2000). Regardless, A S G M certainly has accidents. In June 2002, an electrical fire ignited explosives i n a Shanxi Province gold mine, killing 37 miners (People's Daily, 2002b). Miners had been ordered by management to continue working after a fire had broken out underground. The owners then tried to cover up the blast by secretly removing the bodies at night (People's Daily, 2002a). Table 2.3 lists a variety o f health, safety, and environmental impacts arising from A S G M i n China, i n addition to mercury use.  Table 2.3  Impacts  Item Death  Major health, safety, and environmental impacts o f A S M i n China  and  While underreported, fatalities and serious injuries occur regularly.  accident toll Solid Waste Water  Cyanide  Hazardous Chemicals  Air pollution  Loss of vegetation Water table Subsidence  Sound  A S M tailings and waste rock are arguably the largest source o f industrial waste i n rural China (Andrew-Speed et al, 2003b) While most gold dredges and placer operations are prohibited, many still existed as o f 2002. Dredging for aggregates is widespread, and causes significant sedimentation problems. G o l d producers' cyanidation practices are often questionable and visibly cause significant problems downstream, where fish populations have sometimes disappeared. Cyanide spills have occurred. A wide variety o f chemicals other than cyanide and mercury are often used by A S G M , including acids, flotation reagents, and p H modifiers. These chemicals are rarely closely accounted for or handled safely in a systematic method. Blasts, heavy equipment, and comminution account for significant amounts o f dust and gas emissions. Silicosis and other lung infections appear to be widespread, exacerbated by heavy smoking. In a Jiangxi Province mine, silicosis led to the death o f 100 miners, a quarter o f the mine's workforce (Becker, 2004). Frequently nearby trees are cut for underground support (timbering), and vegetation is often cleared from around mine sites. This loss o f vegetation can lead to erosion and loss o f animal habitat. Dewatering underground mines can lead to a drop i n local water table, affecting agriculture. Shallow, poorly or un-supported underground mining openings can subside, causing damage to surficial buildings or creating dangerous 'glory holes'. China has a special problem with the formation o f sinkholes in karst areas due to mining (Zhou, 1997). L i k e all mining, A S G M operations can be extremely noisy, due to blasts, heavy equipment, and crushing and grinding. Not only do these cause permanent hearing damage to employees, who rarely wear aural protection, but can affect nearby communities and homes. 57  The harsh conditions o f A S G M can also lead to illness. The W o r l d Tibet Network News (1995) reported that artisanal gold miners in Tibet working 14 hour days and subsisting on steamed corn were falling i l l due to diseases such as emphysema.  There have been at least three major cyanide spills i n the past 10 years i n China. In late 2001, in Henan Province, 11 tonnes o f sodium cyanide leaked into the Luohe River due to a road accident involving a truck transporting cyanide to a local gold mine. Thousands of police, soldiers, and civilians were mobilized to contain the spill ( B B C , 2001). In September 2000, a transportation truck released 5.2 tonnes o f liquid sodium cyanide into the Wuguan River i n Shaanxi Province (People's Daily, 2000). Both accidents resulted in fish deaths, but no human casualties. However, a number o f cyanide deaths resulted i n an accident south o f Kuanchung, Hebei Province, i n 1995 (Mortensen, 2003).  2.4.7 Technical Assistance Programs 2.4.7.1 Technical Assistance From the late 1970s to the m i d 1990s, plenty o f government assistance was provided to A S M . To use coal as an example, state-owned coal companies and coal bureaus provided substantial technical assistance to small-scale coal miners i n the late 1970s and early 1980s (Andrews-Speed et al, 2003b), i n an effort to increase national production. The state gold bureaus and companies may have been asked to give A S G M similar assistance at some point. In the 1980s and early 1990s some universities and research institutions provided technical assistance to A S G M (Zhang, 2003). However, since the mid-1990s, there has been little technical assistance available. Equipment manufacturers w i l l often help with equipment installation and provide some initial instructions, after which the miners are left to their own devices. Some governmental agencies, such as the China M i n i n g Association, have small-scale mining departments, but these are too small to offer much direct assistance. 2.4.7.2 Research Cooperation There are a few cases o f research programs or cooperation with A S M i n China. In 1993, the Scientific Committee on Problems o f the Environment ( S C O P E ) initiated a program that studied mercury and A S G M . The Slovenian Institute Jozef Stefan cooperates with  58  the Institute of Geochemistry, at the Chinese Academy of Sciences, in Guiyang, Guizhou Province on mercury-related issues, but A S M is only incidental to their research. Dr. Andrews-Speed, of the University of Dundee, Scotland, researches coal A S M and energy policy in China. Dr. Peter Golas, of the University of Denver, Colorado, undertook substantial A S M research in the 1990s while working on his history of mining in China. 2.4.7.3 Domestic Financial Institutions Bank financing is theoretically available to A S G M , but none of the miners interviewed thought it was a serious possibility, mainly because too much collateral is required. The state-owned mines and TVEs have some access to government finance and would have better access to banks. The private miners studied were entirely financed with private money. In general, China's banking system is in crisis and is not in a position to lend money to small private operations (The Economist, 2002). 2.4.7.4 Non-Governmental Organizations Non-Governmental Organizations are restricted in China, and the regulatory procedures necessary to officially register are often insurmountable. Many of China's NGOs are actually set up by the government with the intention of gaining international funding and have little or no institutional freedom (United States Embassy in Beijing, 2000). In fact, in order to avoid bureaucratic difficulties, a few genuine NGOs have actually registered as businesses (United States Embassy in Beijing, 2000). At its root the Chinese government is suspicious of any non-profit organization that does not owe allegiance to the Communist Party. Existing NGOs tend to focus on educational issues and do not interact with artisanal miners. No international NGOs are known to be involved with A S M issues in China. 2.4.7.5 Multilateral Organizations Virtually none of the major multilateral organizations like the United Nations, the World Bank, or government development agencies like the Canadian International Development Agency (CIDA) have programs to work with Chinese A S M . The only exception seems to be the ILO in cooperation with the Gesellschaft fur Technische Zusammenarbeit (German  59  Development Agency), which helped the Changsha Safety Training Centre for Small & Medium-sized Coal Mines in Hunan province.  2.5  Conclusion  The interviews, field studies, and use o f the H g E X expert system undertaken in this study clearly indicate that A S G M is widespread in China, that mercury use is common and represents a potentially serious health threat. The literature review indicated that this was a woefully understudied area, with few articles o f any variety on the topic. Every site and region visited showed indications o f mercury use from A S G M , be it from muller mills, mercury sluices, or the amalgamation o f concentrates.  Many operations followed  amalgamation o f whole ore with cyanidation.  H g E X provided a valuable tool to assist with the evaluation o f mercury contamination from A S G M i n China. The national alpha factor for China was determined to be 1.0, roughly similar to Brazil, indicating that China is moderately accepting o f amalgamation practices.  In the discussion, what constitutes A S G M i n China is defined and it is determined that roughly 463,000 A S G M miners produced around 61 tonnes o f gold i n 2001, in regions all over China. The number o f these miners' dependants could total almost 3.5 million people. The discussion outlines the complex relationship that A S G M has with the formal and international mining industry and highlights the lack o f formal or informal support enjoyed by A S G M . A S G M is tightly bound with Chinese society through a wide range o f ties and stakeholders, often with conflicting interests.  60  3  Study Two: Artisanal and Small-scale Gold Miners in "Gold Mountain"  3.1  Introduction  The purpose o f this chapter is to develop a case study o f the community o f " G o l d Mountain", in order to elaborate upon and verify the findings o f Chapter T w o . " G o l d Mountain" is a pseudonym for a northern Chinese gold mining village located in the rugged terrain between the Gobi desert and the Y e l l o w River Plains. Geologically, " G o l d Mountain" is located on the northern margin o f the North China (or Sino-Korean) Craton, which underlies much o f north-eastern China and contains hundreds o f gold deposits, most containing less than 1 tonne o f gold (Hart et al, 2002). The gold in these deposits occurs primarily as veins associated with Mesozoic intrusions into mainly Precambrian host rocks (Poulsen and Mortensen, 1993). These veins chiefly contain pyrite, gold, electrum, chalcopyrite, galena, pyrrhotite, magnetite, molybdenite, and trace amounts o f telluride minerals (Zhou et al., 2002). " G o l d Mountain" has hosted A S G M operations for over 70 years and is home to roughly 10,000 people. In addition to gold mining, iron mines and stone and gravel quarries operate in the valley. Agriculture consists primarily of corn and chestnuts i n addition to some tree farms. In the nearby reservoirs, fish farms raise carp.  3.2  "Gold Mountain" - Case Study Methodology  This study describes the community o f " G o l d Mountain", details its gold mining processes, describes a novel mercury retort used locally, and estimates mercury losses and the health and environmental impact due to A S G M . In order to build this case study, several site visits were made between 2000 and 2004.  The following steps were taken: •  Site visits were undertaken i n order to understand in detail every step o f their process and to determine the extent o f A S G M in the community. Sites visited are noted i n Table 2.1, Chapter T w o ;  61  •  Interviews were conducted i n order to gain a more in-depth understanding o f community, the structure o f A S G M i n the village, and the health impact o f amalgamation. People interviewed include mine and plant owners and managers, mine operators and labourers, retired miners, government officials, and local fishermen. During interviews, miners were observed for any signs o f mercuryrelated illnesses, such as muscular tremors or gingivitis.  •  Representative samples o f approximately 200 grams  where  taken  from  intermediate and final tailings and assayed for gold and mercury back i n Vancouver. Shovels full o f tailings were taken from a number o f locations in each tailings pile and then, using the cone and quarter method, the samples were reduced to approximately 200 grams. The samples were returned to Canada and sent for gold and mercury assay using I C P - M S ; and, •  A n estimation o f the total mercury releases from A S G M i n the community was calculated on the basis o f the interviews and samples collected.  3.3  "Gold Mountain" Case Study- Results  3.3.1  "Gold Mountain " Mining and Processing  Practice  In M a y 2001, there were six muller mills located in three different processing centres i n and around " G o l d Mountain". These privately operated centres process ore from local gold mines at a set fee. There is a slightly larger state-owned gold processing operation in the valley, which only uses cyanidation. There are also several small, unlicensed and independent gold processing operations, which exclusively cyanide heap-leach low-grade ores. The ore is supplied to the centres by 40 to 50 small underground mines, mining gold-bearing veins in the area.  Artisanal gold mining operations decreased significantly between 2000 and 2001. In 2000, there were 12 muller mills, another larger gold processing centre, which used leaching technology, and between 70 and 80 mines. L o w gold prices and the increasing difficulty o f processing the ores are the main reasons for the shutdowns. The twisted iron remnants o f discarded muller mills can be found on the outskirts o f the village. However,  62  higher gold prices i n 2002 have revitalized local interest i n gold. This section details stepby-step the A S G M operations i n " G o l d Mountain". 3.3.1.1 M i n i n g Practice Two gold mines were examined i n " G o l d Mountain". The mines consisted Of tunnels about five to six feet tall. Stopes were drilled using pneumatic jacklegs and blasted with dynamite. Miners usually cut into the mountain on one level, then angle down steeply to a gold vein level. Once a vein is found, the miners follow it, blasting out larger openings i f the vein expands. The veins are typically one metre thick, slightly dipping, two or three metres wide, and extending several hundred metres. G o l d grades usually range from 1040 g/tonne. Ore is manually mucked, using handcarts, which are moved between levels by motor-driven winches. Waste rock is usually dumped a short distance from the mine's mouth. From the mine, the ore is taken several kilometres to the m i l l , usually by locally constructed two-cycle 10 tonne ore trucks. Miners often, but not always, wear safety helmets; accidents do occasionally occur. One mine visited employed about 20 people, and the other about 30. Labourers were paid U S $ 72 - 97 per month. Managers received a share o f the profits. 3.3.1.2 Comminution and Amalgamation Two gold processing centres, operating a total o f four muller mills, were studied. The first centre, operating one muller m i l l , employed about 10 people, including a cook, labourers, managers, and security guards. Labourers were paid around U S $ 72 per month. The second m i l l employed closer to 30 or 40 people.  Miners would bring their ore to a milling centre and pay a set fee per tonne o f ore processed, i n addition to paying for any reagents used. Miners would choose the quantity of reagents used i n consultation with the millers. A s all o f the fees were fixed, the millers had little financial interest in the grade o f the ore and were not responsible i f little gold was recovered. A representative  o f the mine would observe all o f the processing  procedures.  63  A t the processing centre, ore would be stored, segregated according to ownership. In turn, each miner's ore is crushed using a jaw crusher. The ore is then shovel fed to a muller m i l l along with several kilograms o f mercury. A steady stream o f water flows into the m i l l , and lime is added to reduce mercury flouring. The ore is ground and put in contact with the mercury by three large iron wheels turning around a circular ironclad track. The fines overflow into a chute and are collected as the slurry passes into several settling tanks, before draining into a small tailings pond. The settled fines are later shovelled out for cyanidation. Random objects (like a hammer from a hammer mill) are placed on the chute to be used as somewhat dubious obstacles to retain mercury. Most overflow material stopped by these objects tends to be washed into the settling tanks during the m i l l cleaning stage. The millers do not use riffles in the sluice box to catch fine gold or mercury, claiming they pose a security risk. Most o f the particles seem to settle in the first few boxes. The final box, considered the m i l l ' s property, takes days to fill. About 10 to 15 tonnes o f ore can be processed per day, or around one tonne per hour.  Figure 3.1  Cleaning the Concentrate From the M u l l e r M i l l  64  A t least once per day, the muller mills are stopped and cleaned out. The ground ore and amalgam are shovelled into a hand basin, where the amalgam is liberated from coarse particles with a water hose (see Figure 3.1). Free iron from the m i l l is collected with a hand magnet. The excess ground material flows into the tanks with the fines. The amalgam is collected and placed i n a thick cloth and manually squeezed, getting rid o f the excess mercury. The amount o f gold recovered by the m i l l varies with the ore, but miners claim it is frequently around 60% to 70%. The mills would operate around 10 to 12 hours per day.  The muller mills are manufactured in a nearby town, and a visit to the manufacturer found a busy and relatively sophisticated operation. In addition to the muller mills, machine tools are used to manufacture jaw crushers and magnetic separators. The iron for the muller wheels is cast on site. The plant has been i n operation for between 15 and 20 years and has sold about 500 gold muller mills to the surrounding region, selling mills for about  10,000 R M B or roughly US$1,200. There was also a smaller muller m i l l  manufacturer i n town. 3.3.1.3 Retorts " G o l d Mountain" processing centres use an uncommon and simple retort. The ball o f amalgam from the muller m i l l cleaning is placed i n a small pan on top o f an electric hotplate, seated i n a water-filled bowl, and then covered with a metal bucket (Figure 3.2; Figure 3.3).  The bucket and the water form an air seal, creating a crude but effective retort. When heated, the mercury evaporates and the mercury vapours condense on the cover-bucket walls and drip into the water-filled bowl. After approximately an hour, the cover is removed and the owner o f the dore takes it home for further purification. A s the temperature reached i n the bucket is likely high, the mercury recovery is probably about 95% (Veiga, 2004b). The condensed mercury appears to coalesce (see Figure 3.4) and is periodically collected and recycled. This simple and cheap retort seems unique to " G o l d Mountain". 65  bucket  evaporated Hg condensed Hg metallic  water  Figure 3.2  Figure 3.3  electric element  bucket  " G o l d Mountain" Retort Diagram  " G o l d Mountain" Retort Photo  Figure 3.4  Mercury Droplets from " G o l d Mountain" Retort  3.3.1.4 Cyanidation and Zinc Smelting The fines from the settling tanks are shovelled out when the tanks are full and the sludge is placed i n piles until the cyanidation tanks are available. Then the ore is shovelled into 10 tonne leach tanks, for vat leaching. About 5 kg o f lime per tonne o f ore are mixed with water or barren leach solution from the previous leach. Then, depending on whether the ore contains oxides or sulphides, 2.5 or 5 kg o f sodium cyanide respectively are added to the solution. This solution percolates through the ore and then drains from the tank to a locked box full o f zinc strips, which collect the gold (Merrill-Crowe Process). N o deaeration takes place, and cyanide is only added once at the start o f the operation. The barren leachate is then re-circulated to the leach tank, with a retention time o f usually seven days. If the ore grade is less than 3 or 4 g/t gold, determined visually from experience or simple panning, then the ore is ground using a hammer m i l l , then added directly to the leach tanks without amalgamation. The operators did not have any method of determining the cyanide or gold concentration in solution.  67  The final discharge is treated with powdered bleach (Ca(OCl)2) to remove the cyanide ions from solution. The primary reaction is:  CN- + ocr = CNcr + cr It is not clear i f the amalgamation tailing discharge is treated.  After the ore is leached, the zinc strips are scooped into a bag and the barren solution is drained off. The loaded strips are taken home, where a furnace w i l l already have been started. The furnace is basically a sturdy iron barrel filled first with wood and then topped off with 200 kg o f coking coal (at $US60 per tonne). The wood is ignited first, and with the aid o f a fan, the coke catches fire. Then the zinc strips are put i n crucibles and placed in the furnace. After 30 to 60 minutes, several scoops o f borax (at $US0.12 per kilogram) are added to the crucibles. After 15 minutes or so, the flux is poured into other crucibles and allowed to cool, with the precious metals settling to the bottom. After being quenched, the crucibles are emptied onto an iron plate and the gold and silver are knocked off the bottom o f the slag. Overall, the miners claim a recovery rate o f about 90%.  N o effort is made to protect against fumes generated during the smelting o f the zinc strips. While the leaching kinetics o f mercury are slower than gold (Flynn, 1995), mercury would both move into the solution and plate on the zinc strips along with the gold. This mercury recovered on the strips would then be volatized in the smelting operation. 3.3.1.5 G o l d Purification Miners typically need to purify their dore, as described in Section 2.3.1.6. 3.3.1.6 " G o l d Mountain" A S G M Cost Structure It is important to understand the economic reality o f the miners in order to understand the dynamics o f their mercury use and i n order to offer realistic alternatives to amalgamation. The following is a breakdown o f the costs and revenue o f one typical miner. H e claimed it cost h i m roughly US$12 to mine a tonne o f ore and another US$5/t to transport the ore  68  to the processing centre. He paid the centre roughly US$1 7/t for processing and reagent fees, leaving h i m with a profit o f US$42/t at a recovery rate o f 90% with a grade o f lOg/t. His cut-off grade is roughly 4 g/t, not including silver. These figures do not include taxes or local corruption ("rent seeking").  Since only six muller mills, each processing 10-15 tonnes o f ore per day, serviced the 40 to 50 mines, the tonnages mined must be less than 3 tonnes o f ore per day, excluding waste rock. A t a 90% recovery o f lOg/t, this would mean a daily production o f about 27g/day per mine, or 90g/day per m i l l . A s the grade can exceed 40 g/t, and the muller mills can process up to 15 tonnes per day, these estimates are conservative.  Table 3.1  Typical M i n e r ' s Revenue and Profits Per Tonne o f Ore  Ore Grade: 10 grams A u / tonne  Local G o l d Price, Summer 2001: $8.45/gram $US/tonne Percentage of ore of cost Item $76.09 Total Revenue (90% recovery) ($US/tonne o f ore) 35.7 $12.08 M i n i n g Costs 28.6 $9.66 Plant Fee $0.96 2.8 Mercury 16.4 $5.56 Other Reagents 2.1 $0.72 Cyanidation 14.3 $4.83 Transportation 100.0 $33.82 Total Costs ($US/ton of ore) Profit (Total Revenue - Total Costs) ($US/tonne)  $42.27  Mercury is included i n the reagent fee, in addition to lime and any further reagents. Miners are charged for the amount o f mercury not recovered after cleaning the muller m i l l . The mercury the miner is charged is for is thus the amount o f mercury in the recovered amalgam (about 6 grams in this example) and the amount mercury reporting to the tailings (approximately 200 to 2500 ppm). Table 3.1 shows that mercury thus represents less than three percent o f the processing costs. In Venezuela, where mercury costs close to five times as much (US$ 20-25), mercury represents around 4% o f the processing cost, not including cyanidation (Veiga and Gunson, 2004).  69  3.3.2 "Gold Mountain " Mercury Releases and Sample Collection Through the site visits and interviews, several estimates o f the amount o f mercury lost by the muller m i l l amalgamation process were determined. These included verbal estimates, records from the processing plants, and assaying tailing samples. 3.3.2.1 M i l l Operator Estimates on Mercury Lost M i l l operators at one processing site i n " G o l d Mountain" estimated that they used 10 kg of mercury per tonne o f ore and lost around 0.5 kg/t. A s the muller mills processed between 10 and 15 tonnes o f ore per day, this would lead to mercury releases o f 5 to 7.5 kg o f mercury released daily for each o f " G o l d Mountain's" six mills. 3.3.2.2 M i l l Data on Mercury Lost The  muller m i l l operators kept records for all o f the ore processed and the amount o f  reagents, including mercury, used at their plants; however, this data was a closely kept secret. Table 3.2 shows sample data on mercury losses, recorded and shared by one " G o l d Mountain" processing centre. The "Mercury used in muller m i l l " column is the recorded mass o f mercury added to the muller m i l l per tonne o f ore. The "Mercury recovered from m i l l " column records the mass o f the excess mercury recovered after squeezing the amalgam with cheesecloth. The "Mercury Lost" column is the difference between these two columns. A s can be seen, the mercury recovered by the retort is only a small fraction of the total mercury used.  Table 3.2  Ore Sample Miner 1 Miner 2  6  " G o l d Mountain" Processing Centre Data  Mercury used in muller mill (kg/tonne) 1.77 2.38  Mercury recovered from mill (kg/tonne) 1.60 2.18  Mercury recovered from retort (kg/tonne) 0.01 0.01 6  Total mercury lost (kg/tonne) 0.16 0.19  Assuming that amalgamation achieving 50% recovery of the gold in an ore grading 20g/t ore, that the  dore consisted of 40% mercury and that the retort recovered 95% of the mercury. 70  3.3.2.3 Sample Collection Data on Mercury Lost In order to assist with mercury emission estimates, a representative sample was collected from both muller m i l l tails and the cyanidation final tails at the centre. The muller m i l l tails had a mercury grade o f 237 ppm, and the cyanidation tails had a grade o f 108 ppm. The muller m i l l tails would indicate a loss o f 0.237 kg/tonne o f ore processed. These numbers are also in line with L i n et al (1997), who reported A S G M tailings i n Dexing County averaged 100-300 ppm mercury. 3.3.2.4 A S G M Mercury Release Estimates Table 3.3 compares the mercury estimates from sections 3.3.2.1-3.3.2.3, and estimates how much mercury is lost per muller m i l l per day, as well as the total for all six mills in the valley, processing from 10 to 15 tonne/day.  Table 3.3  Miner 1 Miner 2 Tails Grade M i l l e r Estimate  Muller M i l l Mercury Loss Estimates Hg Loss (kg/tonne) 0.167 0.2 0.237 0.5  For One Muller Mill 10 tonne/d ore 15 tonne/d ore kg of Hg/day kg of Hg/day 1.7 2.5 2.0 3 3.6 2.4 7.5 5  A s can be seen, the m i l l operator's estimate is far higher than the other two sources; it is also the least verifiable o f the sources and is thus discounted as inaccurate. Based on the remaining two estimates, the total amount o f mercury discharged per muller m i l l would range from 1.7 k g to 3.6 kg/day. While the muller mills may be able to process up to 15 tonnes/day, the average is probably closer to 10. The primary reason for this is that ore is not processed continuously; miners bring i n lots often smaller than 10 tonnes and it takes time to switch from one miner's ore to the next. The best mercury loss estimate is from approximately 1.7 to 2.4 kg per mill/day.  71  Estimating the average gold grade as 20 g/t, and a muller m i l l gold recovery rate o f 60%, the average ratio o f mercury lost per gold recovered would be 14:1 to 20:1. This estimate is conservative, as the recovery rate is probably significantly lower than 60%.  The lost mercury would report primarily to the tails where it would be subjected to cyanidation. A s can be seen from the final tailing mercury levels, much o f the mercury is recovered during cyanidation and cemented on the zinc strips; however, this mercury is later lost during the smelting process. In addition, a significant portion o f the mercury remains in the tailings, as seen in section 3.3.2.3. One processing centre, hosting a single muller m i l l , had an area o f approximately 3000 metres squared. The amalgamation and cyanidation tailings were spread over an area o f approximately 0.1 kilometres squared.  Assuming that six mills operate for at least 150 days per annum, the total mercury discharged i n the community would range from 1.5 to 2.2 tonnes o f mercury per annum. Furthermore, for many years, the amounts may have been twice as much, since there used to be at least 12 muller mills.  3.3.3 ASGM Health and Environmental Impact "Gold  Mountain's" people and environment have endured  artisanal gold mining  operations for over 70 years. G o l d mining, however, is far from being the only local source o f pollution. Farming, with its extensive use o f fertilizers on the hillsides, creates large erosion and runoff problems, and the widespread use o f coal not only effects air quality but also contributes to acid rain. The two-cycle local haul trucks are also a major source o f air and noise pollution. Iron mines and sand and gravel quarries and dimension stone quarries all lead to an assortment o f health and environment problems. However, mercury and cyanide probably create the most serious local problems, and since there are relatively few sources, their effects could be mitigated. 3.3.3.1 Health Impact A s i n the initial study on A S G M in China (Section 2.2.2), during site visits and interviews, miners were observed for overt indications o f mercury related illnesses.  72  Unlike the initial study, one miller interviewed at a processing centre stated that he had been diagnosed with health problems due to mercury exposure.  The miller frequently handled mercury during his workday, through the cleaning o f the muller m i l l , the retorting o f the amalgam, and the smelting o f the cyanidation zinc strips. His illness had reached a point where he was having difficulties with muscle tremors, a symptom o f serious mercury vapour poisoning. He travelled to Beijing to receive more sophisticated medical treatment than was available in " G o l d Mountain", where his hospital urine test showed high levels o f mercury. He was treated, possibly with a chelating agent, and recovered enough to return to work.  Miners interviewed reported that retorts were introduced around 1990, and that the use o f retorts had dramatically reduced the number o f acute mercury vapour poisonings in " G o l d Mountain". 3.3.3.2 " G o l d Mountain" Aquaculture The significant mercury losses in the valley raise the possibility o f bioaccumulation o f mercury in fish in the two local reservoirs. Both reservoirs were visited i n order to evaluate this risk.  The reservoirs were constructed primarily to create a stable source o f water for downstream agriculture. The larger reservoir had several floating fish pens located in deeper areas o f the water. The smaller reservoir was stocked, without using pens. Three varieties o f carp were farmed. The carp were fed pellets made from flour, bone, and fishmeal, processed elsewhere. N o hatcheries were observed locally - fish  farmers  probably bought fingerlings from nearby regions.  Indigenous fish were virtually extinct. There was one local variety o f carp, but it was carnivorous and local fishermen attempted to wipe out the species to protect their own stock. Anecdotally, the locals have stated that they frequently find deformed fish i n the area.  73  The lack of indigenous fish may have been assisted by the A S G M operations. Around 1985 cyanide use became widespread in the area, and the poor treatment of cyanidation releases may explain the death of fish species in the streams and reservoirs. Much of China is heavily polluted due to a wide array of industrial activities; various other explanations are possible.  3.4  Discussion  Clearly "Gold Mountain" has significant mercury releases due to gold amalgamation, raising two key questions. First, what are the impacts of these releases and second, i f these releases are dangerous, how can they be reduced? 3.4.1  "Gold Mountain's"  Processing  Practice  There are two main issues of concern with regard to "Gold Mountain's" amalgamation process. First is the use of muller mills to amalgamate all of the gold ore processed (whole ore amalgamation), not just a concentrate. The second concern is the use of cyanidation following whole ore amalgamation.  Whole ore amalgamation by definition puts all of the ore in contact with mercury, vastly increasing the amount of material contaminated. The key to reducing mercury releases is to encourage the amalgamation of only gravity concentrates, as then only a small portion of the ore is brought into contact with mercury. The high levels of mercury releases demonstrate a need to determine if alternate technologies can be introduced into A S G M processing centres in China, further discussed in Chapters Four and Five.  The practice of following amalgamation with cyanidation raised the question of whether cyanidation increases the mobility of mercury in the amalgamation tailings, further discussed in Chapter Four. 3.4.2  Health and Environmental  Impact of Mercury Releases in "Gold Mountain "  3.4.2.1 Health Impact of Mercury Vapour Mercury vapour pollution continues to be a concern, as demonstrated by the mercury illness described in Section 3.3.3.1. It is not clear that miners always use retorts, or if  74  miners using the " G o l d Mountain" Retort wait until it cools before removing the lid. The impact o f mercury vapour arising from the smelting o f the gold-bearing zinc strips, or during purification o f gold dore may be a significant factor.  While it was not possible to conduct mercury analysis o f locals i n " G o l d Mountain", L i n et al (1997) undertook such studies i n Jiangxi Province. They found urine samples from miners in Dexing averaged 64.73 ug/L and ranged from 3.6 to 539.6 ug/L, with 9 1 % o f the 185 men, women, and children surveyed reporting above 20 ug/L. These numbers are far above the 4 ug/L that the W o r l d Health Organization (1991) considers normal. However, there is no indication that the urine samples were collected over a 24-hour period, as is standard for urine analysis, or that urine creatinine levels were sampled (Wilhelm et al, 1996). Ideally for urine tests, urine should be collected over a 24-hour period i n order to minimize the effect o f dilution from drinking fluids. In order to mitigate the awkwardness o f 24-hour urine collection, creatinine levels can be analyzed in addition to mercury. Emissions o f creatinine, a breakdown product o f creatine, fluctuate little over a 24-hour period, thus creatinine can be use to normalize the concentration o f mercury emissions.  Other non-intrusive procedures have been suggested as possible indicators o f mercury poisoning. These include questionnaires, observing physical behaviours such as touching their finger to their nose, memory tests, or reproducing simple line drawings (Veiga and Baker, 2004). Care needs to be taken to avoid cultural bias with these sorts o f tests. Tests such as these were not undertaken during this study, but are recommended for future work. 3.4.2.2 Bioaccumulation W i t h at least 1.5 tonnes o f mercury being released annually from " G o l d Mountain", mercury bioaccumulation i n fish in the local reservoirs is a real potential. This potential effect appears to be minimized, as the fish farmed i n the local reservoirs are fed food pellets made outside o f the " G o l d Mountain" area. Fish are a luxury food item, hardly a staple, even for wealthier people. In addition, due to the "impoundment  effect,"  bioaccumulation o f mercury occurs widely in reservoirs with no obvious source o f 75  mercury (Stokes and Wren, 1987). Thus, even i f bioaccumulation was demonstrated by testing fish samples from fish farms, it might not be attributable to A S G M , and fish consumption might be low enough not to lead to significant health problems due to methylmercury. Regardless, given the amount o f mercury being released into the environment, it is likely that conditions favourable to bioaccumulation would occur somewhere downstream.  3.5  Conclusion  The " G o l d Mountain" case study clearly verified that artisanal and small-scale gold mining i n China releases significant amounts o f mercury. A l l stages o f the gold mining process were detailed, including a retort design that seems to be unique to " G o l d Mountain". A review o f the cost structure for gold mining in " G o l d Mountain" found mercury to be only 2.8 % o f the overall cost.  M i l l operator interviews, records, and assays o f m i l l tailings led to the conclusion that the ratio o f mercury lost per unit o f gold recovered for muller mills is from 14:1 to 20:1. A sample o f m i l l tailings was found to have a mercury concentration o f 237 ppm, and a sample o f cyanidation tailings had a concentration o f 108 ppm. The small community o f " G o l d Mountain" alone was estimated to release at least one and a half tonnes o f mercury per annum.  Mercury vapour was found to have caused at least one miner to become i l l , although the impact o f methylmercury was less clear. It was recommended  that non-intrusive  procedures be used to highlight possible indicators o f mercury poisoning. The case study demonstrated that key areas o f concern are amalgamation o f whole ore using the muller m i l l and the smelting o f cyanidation zinc strip concentrates without fume hoods.  76  4  Study Three: "Gold Mountain" Alternative Technology Test Program  4.1  Introduction  The high levels of mercury releases found in the "Gold Mountain" case study, and the associated health and environmental risks due to those releases, demonstrated a need to evaluate technology alternatives to amalgamation. In cooperation with a "Gold Mountain" processing centre, three samples were sent to U B C to undertake mineral processing test work. These three samples were not from the same ore body and are not uniform, thus provide insight into the variability of ore that the milling centre must process. This test program also provided an opportunity to verify the results of the initial research on A S G M in China and the "Gold Mountain" case study, and to examine the impact of cyanidation following amalgamation. This chapter describes the objective, methodology and results of test work undertaken on three "Gold Mountain" samples.  4.1.1 Sample GM1 - "Gold Mountain " Feed Ore The first sample consisted of 14.6 kg of feed ore crushed to roughly minus one inch. The feed sample was to come from one of the several mines that bring ore to be processed at the centre. The feed sample was oxidized (reddish ih colour), and contained some organic material and bits of plastic, probably from the shipping sack.  4.1.2 Sample GM2 - "Gold Mountain " Muller Mill Tails The intermediate sample of 11.6 kg was taken from the muller mill overflow, before cyanidation; thus the ore had been ground with mercury and lime. The sample was grey in colour and slightly damp with some course material. It also contained some organic material and bits of plastic.  4.1.3 Sample GM3 - "GoldMountain" Cyanidation Tails The final sample (13.9 kg) was the tails from the cyanidation of the muller mill overflow. The sample was light grey in colour and slightly damp with some course material, in addition to some organic material and bits of plastic.  77  Methodology  4.2  The objectives o f the test work were the following: •  To verify the mercury losses reported i n Chapter Three;  •  To  evaluate  the  potential  alternative  amalgamation/cyanidation techniques.  technology  to  replace  A Knelson Concentrators  the  current  lab-scale M D 3  centrifugal concentrator ( K C - M D 3 ) , in conjunction with cyanidation, was studied as the alternative technology; and, •  To explore the effect o f cyanidation o f mercury tailings on mercury solubility.  4.2.1  Sample GM1 - "Gold Mountain " Feed  The four main tests undertaken on the G M 1 sample are outlined in Figure 4.1.  S a m p l e GM1:  Feed Test W o r k  Homogenize and split 14,600 g sample (GM1-A)  60g Sulfur, Copper, and Tellurium Assay r  (GM1-B)  r (GM1-C)  8012g Sample to Knelson  Grind 1971g to 120 microns  Grind 1985g to 78 microns  I Triple Pass through MD 3.5. Each pass followed by a grind  f  4  Single Pass through Knelson MD 3  Single Pass through Knelson MD 3  r  1 •  (GM1-D)  Grind 2000g to 291 microns  Single Pass through Knelson MD 3 1 •  48 hour leach test  48 hour leach test  257 hour leach test  r Conduct size analysis and submit samples for assay  Conduct size analysis and submit samples for assay  Submit samples for assay  Figure 4.1  G M 1 Test Program  78  4.2.1.1 Sample Preparation and Characterization Once received i n Vancouver, the G M 1 sample was cleaned o f plastic and organic debris. The entire sample was crushed to - 1 0 mesh (-1 mm) using a cone crusher. Using riffles, two representative 30-gram samples were taken for assay. One sample was sent to A C M E Analytical Laboratories to assay for copper, nickel, cobalt, iron, arsenic, antimony, mercury, and tellurium, using I C P - M S . The sample was assayed to determine the background level o f mercury in the feed ore. The other substances were assayed to determine potential problems with gold recovery during cyanidation. The second sample was sent for a total sulphur level assay, in order to determine the sulphides content o f the ore. 4.2.1.2 Gravity Recovery Test The first test is called a Gravity Recoverable G o l d ( G R G ) test. It was conducted with a centrifugal concentrator and provides an indication o f how much gold could be recovered using only gravity methods.  The methodology for the first test ( G M 1 - A ) was as follows: 1) A n 8 k g sample was processed through a 3" Laboratory Knelson Concentrator ( K C - M D 3 ) at a fluidization water flow rate o f approximately 3.5 litres/minute and a rotation rate o f 60 times the force o f gravity; 2) During the test, sub-samples o f the tailings stream were collected for assays; 3) A t the end o f the concentration stage, the concentrate was washed from the inner cone o f the K C ; 4) The K C concentrate was panned to produce a pan concentrate and pan tailings (middlings) sample; 5) The tailings were then ground i n a lab-scale rod m i l l and steps 2 to 4 were repeated, followed by another grind and a final third pass through the K C - M D 3 ; 6) The concentrate and tailings samples were labelled, dried, weighed and sent to an independent local lab for fire assay to extinction.  79  This methodology is based on the concept that progressive size reduction allows the determination o f gold liberated at finer grinds, without over-grinding or smearing any coarse gold. 4.2.1.3 G r a v i t y / Cyanidation Tests In order to evaluate using gravity concentration in conjunction with cyanidation to replace amalgamation followed by cyanidation, the following three tests were undertaken.  The second and third tests ( G M 1 - B and G M 1 - C ) were run side-by-side to compare the effects o f different grind sizes on recovery. 1) The first 2 kg sample was ground 18 minutes to 80% o f the material passing 120 um, and the second 2 k g sample was ground 50 minutes to 80% passing 78 um, using a lab-scale rod m i l l ; 2) Each sample was run through a K C - M D 3 at a fluidization water flow rate o f approximately 3.5 litres/minute and a rotation rate o f 60 times the force o f gravity; 3) A t the end o f the concentration stage, the concentrate was washed from the inner cone o f the K C ; 4) The K C concentrate was panned to produce a pan concentrate and pan tailings (middlings) sample; 5) The concentrates were labelled, dried, weighed and sent to an independent local lab for fire assay to extinction; and, 6) The tailings were dried and weighed, and then proceeded to cyanidation.  Samples G M 1 - B and G M 1 - C were subjected to cyanidation i n bottle roll tests, run as follows: 1) The K C - M D 3 tailings were slurried in a bottle to approximately 40% solids; 2) L i m e was added to the slurry and the p H was adjusted to 10.5; 3) When the p H was stabilized, cyanide was added to give a concentration o f 1 g/L sodium cyanide; 4) Small aliquots o f slurry were removed at 24-hour intervals and the p H and cyanide concentrations determined;  80  5) Cyanide and lime were added as needed to maintain the initial p H and cyanide levels, and the aliquots were collected for gold analysis; and, 6) After 48 hours, the slurry was filtered, washed, and dried. The cyanidation residue was riffled and representative samples o f approximately 500 grams were analyzed for size distribution and submitted for gold assay.  The fourth test ( G M 1 - D ) was run as follows: 1) A 2 kg sample was ground at 65% solids for 3 minutes i n a stainless steel rod mill; 2) The sample was run through a K C - M D 3 at a fluidization water flow rate o f approximately 0.8 litres/minute and a rotation rate o f 60 times the force o f gravity; 3) A t the end o f the concentration stage, the concentrate was washed from the inner cone o f the K C ; 4) The K C concentrate was panned to produce a pan concentrate and pan tailings (middlings) sample; 5) The concentrates were labelled, dried, weighed and fire assayed to extinction; and, 6) The tailings were dried and weighed, and then proceeded to cyanidation.  Cyanidation proceeded using the bottle roll method, as follows: 1) A representative 480g sample o f the K C - M D 3 tailings was slurried in a bottle to approximately 35% solids; 2) L i m e was added to the slurry and the p H was adjusted to 10.5; 3) When the p H was stabilized, cyanide was added to give a concentration o f 0.5 g/L sodium cyanide; 4) Small aliquots o f slurry were removed at several intervals and the p H and cyanide concentrations determined; 5) Cyanide and lime were added as needed to maintain the initial p H and cyanide levels, and the aliquots were collected for gold analysis; and, 6) After 257 hours, the slurry was filtered, washed, and dried. The cyanidation residue was riffled and representative samples o f approximately 500 grams were analyzed for size distribution and submitted for gold assay.  81  4.2.2 Sample GM2 - "Gold Mountain " Muller Mill Tails The test work undertaken on the GM2 sample is outlined in Figure 4.2.  Sample G M 2 : Intermediate Test Work Homogenize and split 11,600g sample  Size Analysis: 600 g  60g Sulfur, Copper, and Tellurium Assay  4710g - 2 passes through MD3  Flask Shaking Test 3X50g  Regrind sample  Filter and Assay  T Submit samples for assay  3 Pass through MD3 rd  Sample and Assay  Figure 4.2  GM2 Test Program  4.2.2.1 Sample Characterization The GM2 sample was cleaned of plastic and organic debris, then screened at 1 mm, dried and weighed. The plus 1 mm material was assayed for gold and mercury. The sample was homogenized with a riffle, and then a dry 650g representative sample was screened with a Roto-Tap for 15 minutes to determine the size distribution. Representative 15-30g samples were pulverized, sealed, and sent for gold and mercury assays to A C M E Laboratories in Vancouver.  Two additional representative 30-gram samples were taken for assay. One sample was sent to A C M E Analytical Laboratories to assay for copper, nickel, cobalt, iron, arsenic,  82  antimony, mercury, and tellurium, using I C P - M S , and the second sample was assayed for total sulphur. 4.2.2.2 Gravity Recovery Test Sample G M 2 was tested using a K C - M D 3 as follows: 1) A 5 k g sample was processed through a K C - M D 3 at a fluidization water flow rate of approximately 3.5 litres/minute and a rotation rate o f 60 times the force o f gravity; 2) A t the end o f the concentration stage, the concentrate was washed from the inner cone o f the K C and the K C concentrate was panned to produce a pan concentrate and pan tailings (middlings) sample; 3) The tailings were passed through the Knelson a second time, and during the test, sub-samples o f the tailings stream were collected for assay; 4) Step 2 was repeated; 5) The tailings were ground for two minutes in a lab-scale rod m i l l ; 6) The tailings were passed a third time, and during the test, sub-samples o f the tailings stream were collected for assay; 7) Step 2 was repeated; 8) The concentrate and tailings samples were labelled, dried, weighed and sent to an independent local lab for fire assay to extinction. 4.2.2.3 Mercury Solubility Test The combination o f mercury use followed by cyanidation gives rise to concern, as residual mercury may be oxidized during the cyanidation process, allowing the mercury to be more easily methylated by bacterial processes. In order to compare the solubility o f mercury i n the tailings before and after cyanidation, a shake flask test was undertaken.  This was completed as follows: 1) T w o representative 50g samples o f G M 2 were placed in a 250 m L Erlenmeyer flask with 125 m L o f distilled water; 2) The flask was shaken at medium intensity on a shake table for 24 hours; and  83  3) The solution was then suction filtered through glass fibre filter paper and submitted for mercury assay using a P S Analytical Millennium M e r l i n System.  This method was adapted from Hinton (2002). 4.2.3  Sample GM3 - "GoldMountain" Cyanidation Tails  The test work undertaken on the G M 3 sample is outlined in figure 4.3.  Sample GM3: Tailing Test Work Homogenize and split 13,900 g sample  Size Analysis: 650 g  60g Sulfur, Copper, and Tellurium Assay  4570g - 2 passes through MD3  T Submit samples for assay  Flask Shaking Test 3X50g  T Regrind sample  Filter and Assay  T 3 Pass through MD3 rd  I Sample and Assay  Figure 4.3  G M 3 Test Program  4.2.3.1 Sample Characterization The G M 3 sample was characterized i n an identical manner to G M 2 , except the initial screen sample was approximately 650 grams, not 600 grams. 4.2.3.2 Gravity Recovery Test The G M 3 sample was tested i n an identical manner to G M 2 .  84  4.2.3.3 Mercury Solubility Test The G M 3 sample was tested alongside the G M 2 sample, i n an identical manner.  4.3  Results  4.3.1  Sample GM1 - "GoldMountain"Feed  4.3.1.1 Sample Characterization The assay results o f the initial sample characterization for G M 1 are displayed i n Table 4.1. The high copper and sulphur levels, and the presence o f tellurium, indicate the presence o f copper sulphides and gold tellurides, which would inhibit cyanidation. The mercury level o f 788 ppb can be taken as an indication o f the background level o f mercury i n the gold ores. A s this is far less than the mercury concentration i n the muller m i l l or cyanidation tails, the background mercury levels are considered negligible.  Table 4.1  Cu (ppm)  Ni (ppm)  Co (ppm)  4418.2  205.8  37.2  G M 1 Sample Characterization  Fe (%)  12.1  As (PPm)  Sb (ppm)  Hg (ppm)  Te (ppm)  Sulphur  10.5  1.4  0.788  13.7  6.08  (%)  4.3.1.2 Gravity Recovery Test Table 4.2  G M 1 - A Gravity Recoverable G o l d Test  Mass Size Dist'n (um) Product P80 = 475 Pan Cone.  P80 = 236  P80 = 117  Middlings Sample Tails Pan Cone. Middlings Sample Tails Pan Cone. Middlings Final Tails Totals (Head) Knelson Cone.  (g) 8.7 84.1 169.3 17.8 67.7 122.0 27.1 69.8 7445.5 8012 275.2  (%) 0.11 1.05 2.11 0.22 0.84 1.52 0.34 0.87 92.93 100.0 3.43  Assay Au (g/t)  Dist'n  2817 70.40 40.80 2520 95.60 33.30 1882 127.00 26.60  7.0 1.7 2.0 12.8 1.8 1.2 14.5 2.5 56.5 100.0 40.4  43.76 514.6  (%)  85  A s can be seen i n Table 4.2, the grade o f the ore sample is calculated to be 43.76 g/t gold in test G M 1 - A . The test indicated that around 40% o f the gold could be recovered by gravity methods. The 80% passing particle size for the initial pass was 475 um, 236 um for the second pass, and 117 um for the third. The gold recovered increased with each grind, suggesting that most o f the gold is quite fine. The gold recovered would be relatively easy to upgrade, as most o f the recovered gold reported to the pan concentrate. 4.3.1.3 Gravity / Cyanidation Tests The three gravity / cyanidation tests results can be seen i n Tables 4.3, 4.4, and 4.5.  While not reflected in the gravity recovery stage, the increased grind time seems to have improved G M l - C ' s cyanidation recovery over G M 1 - B . A s can be seen, the G M 1 - B and G M 1 - C tests' total recoveries are significantly less than G M 1 - D , primarily due to the significantly shorter leach time. The long leach times used by the miners i n " G o l d Mountain" thus seems justified.  Table 4.3 GM1-B  Product Pan C o n Pan Middlings C N Solution (48 hr) Tails Total Total Recovery  G M 1 - B Test Results  120 um  Mass (g)  Mass (%)  A u (g/t)  A u Dist'n (%)  7.09 3.38 n/a 1974.63 1985.10  0.36 0.17 n/a 99.47 100.00 0.53  701.30 46.30 n/a 22.57 43.33  23.0 0.3 25.5 51.2 100.0  Table 4.4  48.8  G M 1 - C Test Results  GM1-C  78 um  Product  Mass (g)  Mass (%)  A u (g/t)  A u Dist'n (%)  28.06 5.14 n/a 1937.60 1971  0.36 0.17 n/a 99.47 100.00 0.53  2959.90 229.70 n/a 21.26 46.09  22.9 0.9 30.3 45.9 100.0  Pan C o n Pan Middlings C N Solution (48 hr) Tails Total Total Recovery  54.1  86  Table 4.5 GM1-D  291  Product  GM1-D Test Results  nm  Mass (g)  Mass (%)  Au (g/t)  Au Dist'n (%)  112 n/a 1888 2000  5.60 n/a 94.40 100.00 5.60  321.50 N/a 21.26 49.63  36.28 52.18 11.54 100.00  Knelson Con C N Solution (257 hr) Tails Total Total Recovery  88.46  The mass of the gravity concentrate for samples GM1-B and GM1-C are unusually low, as the KC-MD3 concentrates are usually around 100 to 120 g. The GM1-B and GM1-C tests were conduced on an older K C - M D 3 , which sometimes rejected lighter material in the concentrate bowl during the process of shutting down the machine for cleaning. While the gold recoveries do not seem to have been significantly affected, a higher mass pull would likely have made the overall recovery higher, although the grade would be correspondingly lower.  GM1-D Leach Time too 90 80 70 60  • G M l - D (291 um)  50 40 30 20 10 0 50  100  150  200  250  300  Leach Time (Hrs)  Figure 4.4  G M l - D Leach Time  87  The ore has an extremely slow leaching rate, as shown in Figure 4.4. Figure 4.4 does not include the gold recovered in the aliquots for GM1-D, which boosts the overall cyanidation recovery of the KC-MD3 tailings by 25.9%.  Table 4.6 Size (urn)  +150 +63 +45 +38 -38 Total  GM1-B and GM1-C Cyanidation Tailings Analysis  (GM1-B) P80 120 nm A u (ppm) A u Dist'n (%)  28.50 28.45 21.41 18.25 15.24 22.57  4.5 51.8 17.0 8.7 18.0 100.0  (GM1-C) P80 78 nm Au (ppm) A u Dist'n (%)  5.01 17.05 25.13 26.34 19.50 21.26  1.2 15.2 31.0 27.4 25.2 100.0  G M 1 Cyanidation Tails A u Distribution too  90 ~  Au P80 - 60 ".m  80  9  / /  Au 1*80 -  •  1  102  4  um  — • — Au Dist 120 um  aLU  i i—  LMSI io  urn  i  0  100  10  1000  Size (|im)  Figure 4.5  GM1-B and GM1-C Cyanidation Tailings Analysis  The effects of additional grinding on the ore are shown in Table 4.6 and Figure 4.5. Grinding sample GM1-C down to 78 um significantly increased the gold recovery in the +45 um range. The cyanidation tailings from the GM1-B sample, with the coarser grind, show that the ore retained 52% of its gold in the -150 um to + 63 um size fraction, where sample GM1-C retained only 15% of its gold in the same fraction. The overall recovery  88  o f G M 1 - C was  5 4 . 1 % versus 4 8 . 8 %  for G M 1 - B ,  p r i m a r i l y due  to the  improved  c y a n i d a t i o n r e c o v e r y as a result o f increased g r i n d i n g .  4.3.2  Sample GM2 - "Gold Mountain " Muller Mill Tails  4.3.2.1 S a m p l e C h a r a c t e r i z a t i o n A f t e r p i c k i n g out the o b v i o u s l y a l i e n m a t e r i a l , the + l m m o v e r s i z e w a s 2 0 4 g, w i t h 46.7 g/t g o l d a n d 1231 p p m m e r c u r y . T h i s o v e r s i z e material w a s assayed for g o l d a n d m e r c u r y and i n c l u d e d i n the size and grade d i s t r i b u t i o n data. H o w e v e r , it w a s not i n c l u d e d i n any further test w o r k , as it w a s a r e l a t i v e l y s m a l l amount, at 1.75% o f the total mass, and it w o u l d have n e e d e d to be crushed before it c o u l d be passed t h r o u g h the  centrifugal  concentrator.  T h e P 8 0 for sample G M 2 w a s f o u n d to be 180 u m . T h e b a c k c a l c u l a t e d assay for g o l d was 4 1 . 4 2 g/t. F o r m e r c u r y , the b a c k c a l c u l a t e d assay w a s 2 3 5 0 p p m . T h e s i z e analysis for G M 2 s h o w e d that 5 2 % o f the g o l d a n d 5 3 % o f the m e r c u r y w e r e f o u n d i n the - 5 3 u m size fraction, representing 2 6 % o f the total mass.  GM2 Size, A u , a n d H g D i s t r i b u t i o n  1  on yu  'w'  .2  /*  7 n  /u  60 -  •  CO  m  CM  Size Dist  — • — A u Dist  SA in .  1  A  H g Dist  ON  20 10 • 0 0 1  1()0  1000  Size ((im) F i g u r e 4.6  G M 2 S i z e , G o l d , and M e r c u r y D i s t r i b u t i o n s  A s s h o w n i n F i g u r e 4.6, the g o l d d i s t r i b u t i o n c l o s e l y m a t c h e d the m e r c u r y d i s t r i b u t i o n .  89  Table 4.7  GM2 Sample Characterization  Cu (ppm)  Ni (ppm)  Co (ppm)  Fe  As (ppm)  Sb (PPm)  Hg (ppm)  Te (ppm)  Sulphur  41065  117  32  7.09  7.7  43.6  2350  5.3  6.34  (%)  Table 4.7 shows that GM2 has a high copper content, at 4.1%, demonstrating that samples GM1, GM2, and GM3 are not from uniform ore bodies. The tellurium in the GM2 sample is significantly lower than that in the GM1 sample, which indicates that either amalgamation is recovering some tellurium with the gold, or that the sample simply has less tellurium than GM1. The high copper and high sulphur content may indicate that the copper is in the form of sulphides, such as chalcopyrite. 4.3.2.2 Gravity Recovery Test As can be seen in Table 4.8, the GM2 test results calculate the grade of the sample to be 38.1 g/t gold, lower than the sample characterization assay results. The test indicated that around 43% of the gold could be recovered by gravity methods, which is surprising considering this sample had already been amalgamated. Table 4.8  GM2 Gravity Test Results Assay  Units  Dist'n  (%)  A u (g/t)  Au  30.9 62.0 13.3 68.8 305.7 24.7 58.7 4145.9 4710  0.66 1.32 0.28 1.46 6.49 0.52 1.25 88.02 100.0  1447 157 537 75.2 23.4 336 49.8 22.8  948.7 206.7 151.6 109.8 151.9 176.2 62.1 2006.9 3813.9  (%)  258.4  5.49  302  Mass  Size Dist'n P80= 144 jim  P80= 100 nm  Product  Pan Cone. Middlings Pan Cone. Middlings Sample Tails Pan Cone. Middlings Final Tails Totals (Head) KC-MD3 Cone.  (g)  38.1  24.9 5.4 4.0 2.9 4.0 4.6 1.6 52.6 100.0 43.4  The size distribution for the initial pass was 80% passing 144 um, lower than the initial size distribution, as the plus 1 mm material was not included. After the two minute grind the P80 was 100 um. Over 30% of the gold was recovered in the first stage, suggesting  90  that additional grinding may not be economical. In addition, the gold recovered in the first pass would be relatively easy to upgrade, as most o f the recovered gold reported to the pan concentrate. 4.3.2.3 Mercury Solubility Test A s this test was primarily undertaken to compare G M 2 and G M 3 ' s mercury solubility, these results are examined together i n section 4.3.3.3.  4.3.3  Sample GM3 - "Gold Mountain " Cyanidation Tails  4.3.3.1 Sample Characterization  G M 3 Size, A u , a n d H g D i s t r i b u t i o n _  tnn  on yu SO  r "  an  */ .5  CO CO  60 -  m Cu  en  "fl  40  >  '  0  •  Size Dist  —•— A u Dist  •  A  Hg Dist  a ™  <u Pm  in xU  i1U n  o1()0  I0  1000  Size l fims)  r  Figure 4.7  G M 3 Size, Gold, and Mercury Distributions  After picking out the obviously alien material, the + l m m oversize was 305 g, with 1.31 g/t gold and 82 ppm mercury. This oversize material was assayed for gold and mercury and included i n the size and grade distribution data. It was also not included in any further test work, as it was a relatively small amount at 2.18% o f the total mass, and it would have needed to be crushed as well.  The P80 for sample G M 3 was found to be 215 um. The back calculated assay for gold was 1.58 g/t. For mercury, the back calculated assay was 283 ppm. The size analysis for  91  G M 2 showed that 36% o f the gold and 48% o f the mercury were found i n the -53 nm size fraction, representing 2 3 % o f the total mass. A s can be seen i n Figure 4.7, the gold distribution was not closely tied to the mercury distribution. Clearly cyanidation successfully recovers gold in preference over mercury.  Table 4.9  Cu (ppm)  Ni (ppm)  Co (ppm)  9356  87.7  17  Fe  (%)  4.48  G M 3 Sample Characterization  As (ppm)  Sb (ppm)  Hg (ppm)  Te (ppm)  Sulphur  13.8  63.04  283  4.02  3.24  (%)  Table 4.9 indicates that copper grade is still relatively high, at almost 1%. Except for the arsenic and antimony content, the other metal contents were significantly lower than i n G M 2 , suggesting that the leaching process removes a lot o f the other metals, slowing the extraction o f gold. 4.3.3.2 Gravity Recovery Test Table 4.10  G M 3 Gravity Test Results  Mass Size Dist'n  Product  P80= 121 Jim  Pan Cone. Middlings Pan Cone. Middlings Sample Tails Pan Cone. Middlings Final Tails Totals (Head) KC-MD3 Cone.  (g) 25.1 59.3 37.6 48.4 90.1 42.1 44.9 4570.5 4918  (%) 0.51 1.21 0.76 0.98 1.83 0.86 0.91 92.93 100.0  257.4  5.23  Assay Au (g/t)  Units Au  Dist'n  10.8 2.03 5.19 2.28 1.33 10.7 2.46 0.78  5.5 2.4 4.0 2.2 2.4 9.2 2.2 72.5 100.5  5.5 2.4 3.9 2.2 2.4 9.1 2.2 72.1 100.0  1.01 4.89  (%)  25.4  A s can be seen i n Table 4.10, the G M 3 test results calculate the grade o f the sample to be 1.01 g/t, lower than the sample characterization assay results. The test indicated that around 25.4% o f the gold could be recovered by gravity methods, which would perhaps be uneconomical considering the low grade. The size distribution for the initial pass was not recorded, but after the two-minute grind the P80 was 121 um. The recovered gold  92  was widely distributed between the pan concentrates and middlings, and the concentrate grades low, suggesting that the gold may not be easy to upgrade. 4.3.3.3 Mercury Solubility Test The intermediate mercury tails from the muller m i l l ( G M 2 , 2224 ppm Hg) were compared to final tails following amalgamation and cyanidation ( G M 3 , 285 ppm Hg), using two duplicate samples ( A and B ) . The mean value o f G M 2 ' s solution had a concentration o f 15.34 ug/L mercury and G M 3 ' s solution mean had a concentration o f 3.78 ug/L mercury. However, since G M 2 ' s overall mercury levels are an order o f magnitude higher than G M 3 ' s , the ratio o f mercury dissolved to the mercury present in the sample was compared. A s seen in Table 4.11, approximately twice the ratio o f mercury was dissolved from the cyanidation tails sample G M 3 , compared to the intermediate sample: 17.2 x 10" for G M 2 and 31.1 x 10" for G M 3 . 6  6  Table 4.11  Product  Mercury Solubility  GM2 (2224ppm Hg) Ratio of Hg (\ig) in solution to Hg Oig/LHg) in tailings (u.g)  Sample A Sample B Mean  14.30 16.37 15.34  b  6  Discussion  4.4.1  "Gold Mountain " Samples Table 4.12  5.14 2.41 3.78  16.1 x 10" 18.4 x 10" 17.2 x 10""  4.4  G M 3 | [285ppm Hg) Ratio of Hg (ng) in solution to Hg (Hg/LHg) in tailings (u.g) 45.1 x 10"° 21.1 x 10" 31.1 x 10" 6  b  Grade Differences Between Test Samples  SAMPLES G M 1 - Feed Sample G M 2 - After Muller, Cyanide G M 3 - Final Tails  Cu (%)  Fe (%)  Te (ppm)  Hg (ppm)  0.44  12.11  13.71  0.78 2224  4.11 0.94  7.09 4.48  5.30 4.02  Pre  285  The three " G o l d Mountain" samples are clearly not from the same ore deposit, as is demonstrated i n Table 4.12. While this presents difficulties comparing the test work, it shows the diversity o f ores that a mineral processing centre in " G o l d Mountain" receives.  93  It also demonstrates that any alternative technology introduced needs to be robust enough to handle a diversity o f ores.  The mercury levels in the samples are significantly higher than the initial samples collected during the case study research; 2350 ppm vs. 237 ppm for the muller m i l l intermediate samples ( G M 2 ) , and 283 ppm versus 108 ppm for the final cyanidation tails ( G M 3 ) . This verifies that the estimates o f mercury releases made i n section 3.3.2.4 are certainly conservative.  Detailed studies o f the mineralogy o f samples G M 1 - G M 3 was not undertaken. While this may have provided further information on how to optimize the recovery o f gold in these samples, the variability o f the samples suggest that such an optimization might not be useful for the range o f ores brought into a processing centre. The miners need inexpensive, simple, and robust technology capable o f achieving good gold recoveries from a range o f ores. 4.4.1.1 G M 1 The G M 1 test work verified that a significant portion o f the ore is amenable to gravity separation, with a G R G value o f 40%. The test work also showed that the long leach times used are indeed necessary, and that increased grinding would improve both gravity and cyanidation recoveries. The miners had indicated that some o f the gold ores were especially refractory, and that they were interested i n new technologies to improve recovery. It is quite possible that the G M 1 sample was one o f these ores, due to the high tellurium grade and the high percentage o f gold finer than 63 um. That after almost 11 days o f cyanidation i n a bottle roll, the tailings grade was still 5.6 g/t gold, indicates that the miners may have had significant difficulties achieving high recoveries. This slow leach time may be due to the copper and tellurium in the ore.  Miners may improve recovery by adding cyanide i n stages. A s mentioned i n section 3.3.1.4, miners only add cyanide and lime at the beginning o f cyanidation. The miners could float and/or roast the ore to improve recoveries, but this would likely be beyond the miners' technical skills or financial capability. 94  4.4.1.2 G M 2 The high gold grade o f G M 2 (38.1 g/t), and the exceptionally high mercury levels (2224 ppm) suggests the amalgamation process was not especially effective in this case. Usual whole ore amalgamation tails have mercury levels in the range o f 200 to 500 ppm (Section 3.3.2.3; Veiga, 1997). Perhaps the feed ore had a particularly high grade (over 60 g/t gold), and the miners had some inkling o f this, thus added significant amounts o f mercury i n an attempt to increase recovery. The tight correlation between the mercury and gold size distribution (Section 4.3.2.1) indicates that amalgamation i n the muller mills may be extremely effective; potentially all o f the gold is essentially amalgamated. However, this sample is from the muller m i l l tailings; clearly the amalgam is not being effectively recovered from the m i l l . While " G o l d Mountain" miners stated that amount o f gold was in the range o f 40-60%, it seems unlikely i n this case. While the muller m i l l may be an efficient and inexpensive comminution and amalgamation device, it may not excel at gold recovery. This is corroborated by the high percentage o f gold recovered by the K C - M D 3 i n the first pass. One o f the prime causes for this may be that muller mills can flour the mercury, grinding it fine enough that it becomes largely inactive due to impurities and its inherent surface tension. Another reason may be that cleaning the muller mills by only removing the material found at the bottom o f the muller m i l l trough is ineffective. Perhaps special amalgamation plates (Veiga and Gunson, 2004) would effectively remove much o f the amalgam in the overflow. Presumably much o f this excess mercury would be recovered using cyanidation and volatized during the zinc strip smelting, to the hazard o f the miners. 4.4.1.3 G M 3 Sample G M 3 demonstrates that on some ores, the " G o l d Mountain" processing centres can be quite efficient at gold recovery. The low gold grades (—lg/t) and the poor results on the gravity tests (25.4% after three passes) indicate that their process (or at least their cyanidation) was effective, even with a high copper grade to inhibit cyanidation, unless the initial grade o f this ore was quite low. Reprocessing tailings may not be an attractive option in " G o l d Mountain". The lower grade o f mercury in the cyanidation tails compared to the amalgamation tails (283 ppm versus 2224 ppm), suggests that much o f  95  the mercury from the amalgamation process is recovered during cyanidation. This recovered mercury is subsequently volatized during the smelting o f zinc strips, described in section 3.3.1.4. Obviously, uncapped tailings dumps often located beside streambeds, with mercury concentrations 283 ppm, are a significant risk to the local watershed.  4.4.2 Mercury Solubility The United States Environmental Protection Agency's ( U S E P A , 2002) guidelines state two figures for freshwater mercury contamination. Its Criteria M a x i m u m Concentration ( C M C ) is an "estimate o f the highest concentration o f a material in surface water to which an aquatic community can be exposed briefly without resulting i n an unacceptable effect." Its Criterion Continuous Concentration ( C C C ) is an "estimate o f the highest concentration o f a material i n surface water to which an aquatic community can be exposed indefinitely without resulting in an unacceptable effect." The C M C and C C C for mercury i n freshwater is 1.4 ug/L and 0.77ug/L respectively ( U S E P A , 2002). Metallic mercury is a relatively stable substance, so significant dissolution shows the presence o f soluble species. Thus the G M 2 and G M 3 ' s dissolution concentrations o f 15.34 and 3.78 ug/L mercury give rise to concern.  The leaching kinetics o f mercury during cyanidation are fast, but slower than those o f gold. A s a result, only part o f the mercury is leached, the rest remaining with the tailings. In gold leaching conditions, mercury forms [Hg(CN)4] ", through the following equation: Hg  2 +  + 4NaCN = Hg(CN) " + 4Na 2  2 +  4  [ H g ( C N ) 4 ] " can easily form complexes with other substances (Flynn, 1995). 2  A s the tailings are disposed o f beside the local stream and no effort is made to safely manage the tailings, rainwater could easily mobilize this mercury. Hinton et al (2003a) suggest a number o f options for remedial solutions for mercury-contaminated sites. The difficulty is that funding probably would not be available for clean up. Foremost efforts should be put toward helping existing operations use less damaging methods.  96  4.5  Conclusion  The test work completed verified that high levels o f mercury were being released from " G o l d Mountain's" processing centres. The muller m i l l tailings' mercury concentration was 2224 ppm, and the cyanidation tailings' concentration was 285 ppm mercury, from a background mercury concentration, as indicated by the feed ore, o f only 0.78 ppm. The three samples were from different deposits and show the diversity o f ores that milling centres must process.  Test work completed on the feed sample, grading about 43 g/t gold, indicated that around 40% o f the gold was recoverable by gravity methods. A n eleven-day cyanidation bottle test showed that the leaching rate o f the ore is extremely slow, perhaps due to the high levels o f copper (0.44%) and tellurium (13.71 ppm) in the ore. Gravity methods could be introduced to replace whole ore amalgamation, although amalgamation o f gravity concentrates  may still be necessary to produce a saleable product for the miners.  Increased comminution would help the miners achieve higher recoveries and potentially reduce cyanidation times.  The muller m i l l tailings sample, with a gold grade o f 38.1  g/t,  indicated that  amalgamation had not effectively recovered gold from the initial ore, especially as 43% of the gold i n the tailings was recovered, 30% in the first pass without additional grinding.  The cyanidation tailings sample, with a gold grade o f 1.0 g/t, indicates that for this ore at least, the processing centre effectively recovered most o f the gold. The mercury concentration indicates that much o f the mercury from the muller m i l l is removed by cyanidation, to be volatilized during the zinc strip smelting process. The remaining mercury i n the tailings also represents a significant risk to the local watershed. In addition, the mercury solubility tests indicate that cyanidation, following amalgamation, may increase the solubility o f the mercury i n the tailings. The miners should be encouraged to abandon their practice o f whole ore amalgamation, although amalgamation of gravity concentrations may continue to be necessary.  97  5  Mercury Releases, Alternatives, and Implementation  A s demonstrated i n the previous three chapters, China's artisanal and small-scale gold mining industry releases significant amounts o f mercury. This chapter brings together the results o f the previous chapters to estimate the extent o f mercury released by A S G M , discusses potential technology alternatives to amalgamation which could reduce those releases and examines some issues surrounding alternative technology and technology transfer.  5.1  China's Mercury Releases  A S G M represents one o f the main sources o f mercury releases in China, but is by no means the only source. First, the releases due to A S G M are estimated, followed by a brief discussion o f other sources o f mercury.  5.1.1  Estimating China's ASGM Mercury Releases  The following mercury emission estimate for A S G M is based on: •  The estimate o f China's annual gold production due to A S G M ( A S G M A u ) ;  •  Estimates o f the methods o f A S G M gold production; muller mills, ball mill/mercury sluice combinations, and placer methods; and,  •  Estimates o f the ratio o f mercury lost to gold recovered by these different methods.  Thus, the annual mercury emission from Chinese A S G M production is estimated from the following equation: HgAu - ASGMAu*(MMAu%*MMR+BSAu%*BSR+PMAu%*PMR) Where: H g A u is the amount o f mercury released per annum due to A S G M activities; A S G M A u is the amount o f gold produced per annum by A S G M ; M M A u % is the percentage o f gold produced by A S G M operations using muller mills (Section 2.3.1.1); M M R is the ratio o f mercury lost to gold recovered for muller mills; B S A u % is the percentage o f gold produced by A S G M operations the ball mill/sluice combination (Section 2.3.1.2);  98  B S R is the ratio o f mercury lost to gold recovered for ball mill/sluice operations; P M A u % is the percentage o f gold produced by A S G M operations exploiting placer deposits (Section 2.3.1.3); and P M R is the ratio o f mercury lost to gold recovered from placer deposits.  The annual A S G M gold production estimate ( A S G M A u ) is 61 tonnes per annum, based on the calculation i n section 2.4.2.2.  The estimates o f the percentages o f different A S G M gold production methods are the least certain o f these estimates. B a l l m i l l / sluice operations were found widely around China, as discussed i n Chapter T w o , and have the capacity to m i l l large amounts o f ore. He et al (2000) demonstrated that this is the main amalgamation method for the smaller state-owned gold operations using amalgamation. There appeared to be large numbers o f muller mills, but they were more localized, and thus are given a smaller share o f total production. Placer gold makes up around 13% o f China's total gold production and often producers are small-scale operations (Zhou et al, 2002).  Estimates o f the ratio o f mercury lost to gold recovered by method are detailed i n Table 5.1. The muller m i l l estimate ratio ( M M R ) Hgi :Aup oduced ranges from is 14:1 to 20:1, as ost  r  demonstrated i n section 3.3.2.4. The ball m i l l / sluice ratio ( B S R ) range was determined as follows. H e et al (2000) provide data for 33 ball m i l l / sluice operations, and claim that they consumed mercury at a Hgi st:Au roduced ratio o f 6.35:1. O n average, 75% o f the 0  P  mercury consumed was later recovered using retorts and active carbon filters, leaving a ratio o f 1.59:1. W h i l e this is probably representative o f the state-owned amalgamation mills, it may be an underestimate in the case o f the smaller A S G M operations. Section 2.3.1.4 estimated the ratio as 3.33:1, based on interviews. However, mercury losses from a similar copper plate amalgamation process described by V e i g a and Gunson (2004) revealed a Hgi t:Aup duced ratio o f 1.5:1-2:1. A s He et al (2000), and V e i g a and Gunson os  ro  (2004) produced more verifiable results than the interviews could have done, the B S R used for the l o w range is He et al's average o f 1.59:1 and the high range is 2:1. The ratio used for the placer operations ( P O R ) is 1. A s no whole ore amalgamation placer  99  operations were observed i n China, it was assumed that they only  amalgamate  concentrates. For a l l o f these methods, the actual ratios vary widely with equipment quality, human ability and ore variation.  Table 5.1  Mercury to G o l d Loss Ratio for China  Unit  Abbreviation  Mercury Lost: Gold Produced  Source  Muller M i l l s , China B a l l m i l l - Sluice, China B a l l m i l l - Sluice, China Amalgamation Plate Only Concentrate  MMR BSR BSR ~BSR PMR  14-20 : 1 3.33 : 1 1.59 : 1 1.5-2 : 1 1: 1  Section 3.3.2.4 Section 2.3.1.4 He etal, 2000 Veiga and Gunson, 2004 Veiga, 1997  Estimates o f the total amount o f mercury released due to A S G M i n 1997 and 2001 are outlined i n Table 5.2. For 2001, the l o w estimate is 237.6 tonnes o f mercury per annum and the high estimate is 652.1 tonnes.  Table 5.2  Chinese Annual Mercury Releases attributable to A S G M  Factor ASGMAu MMAu% MMR BSAu% BSR PMAu% PMR HgAu  1997  20()1  Low 58 20 14 50 1.59 30 1  High 87.5 30 20 45 2 15 1  Low 61 20 14 50 1.59 30 1  High 92.5 30 20 45 2 15 1  225.9  616.9  237.6  652.1  The ratio o f mercury lost to gold recovered seems to be the standard method used for accounting for mercury losses (Veiga, 1997). However, it is an imperfect standard for two main reasons; it does not account for mercury lost when no gold is recovered, and it assumes that miners w i l l accurately report the amount o f gold they are recovering. It is easier to learn how much mercury is being lost per day per tonne o f ore processed than it is to discover its ratio to gold recovered, as the former does not require miners to be  100  honest i n reporting their gold recovery and can be verified by assaying tailings. Ideally the amount o f mercury that miners buy each month could be recorded.  Table 5.3  L o w Estimate o f A S G M G o l d Production and Mercury Releases (2001)  Method  Au Production (tonnes/a)  Muller m i l l B a l l m i l l / sluice Placer methods Total  12.2 30.5 18.3 61  Au Production (%) 20 50 30 100  Hg Releases (tonnes/a) 170.8 48.5 18.3 237.6  Hg Releases (%) 71.9 20.4 7.7 100  A s can be seen i n Table 5.3, by far the largest contributors to mercury releases are muller mills, with 20% o f A S G M production and 72% o f the mercury releases, even using the low end o f the range o f Hgi :Aup oduced ratios. Muller mills are clearly the area where ost  r  efforts at reducing mercury releases should be concentrated. 5.1.2  Other Sources of Mercury  In addition to A S G M , China has several other sources o f mercury releases.  He et al (2000) described how China's gold mines release around 20 tonnes o f mercury per annum. The mines covered i n the article are most likely the state-owned mines that still use amalgamation, and generally would not overlap with the mercury releases described above.  China's massive coal mining industry emitted around 303 tonnes o f mercury from coal combustion i n 1995 alone (Wang et al, 2000). Artisanal and small-scale coal mines contributed around 127 tonnes o f mercury i n 1997 (Gunson and Veiga, 2004). Feng and Hong (1999) determined that most o f this mercury was associated with sulphides i n the coal and could be removed by basic coal cleaning, at least i n Guizhou Province. In 2001, China produced roughly 1089 million tonnes o f coal, but due to the central government's policy o f shutting down A S M coal mines, their share o f production has dropped from 47%  i n 1996 to 2 3 % i n 2001 (Andrews-Speed et al, 2003b). Assuming an average  101  mercury content o f 0.22 mg/kg i n China's coal, A S M coal mines contributed around 56 tonnes o f mercury and formal coal mines contributed 240 tonnes o f mercury in 2001.  A s detailed in Gunson and Veiga (2004), some 50 A S M mercury operations lose around 28 tonnes o f mercury per annum (in addition to their mercury production). The formal mercury-mining sector would also contribute to mercury releases; however, apparently most o f the state-owned mercury mines have now been shut down (Maxson, 2004). In 2001, China's state-owned mercury mining sector produced approximately 190 tonnes o f mercury, down from 830 tonnes i n 1997 (Tse, 2002). Assuming a 90% recovery rate o f mercury, the state-owned mercury mines released around 19 tonnes o f mercury i n 2001. The mines' production should not be considered releases, since much o f that mercury may make it to A S G M operations or mercury polluters and would thus lead to double counting.  There is a wide variety o f other sources o f mercury pollution including: •  Chlor-alkali plants (1400-2700 tonnes from 1952-2000, Q i et al, 2000);  •  Batteries  •  O i l product combustion;  •  Cement production;  •  Lead production;  •  Zinc production;  •  P i g iron and steel production;  •  Caustic soda production;  •  Waste disposal; and,  •  Deforestation (Pacyna and Pacyna, 2002).  Maxson (2004) estimates that the total amount o f mercury consumed i n East A s i a in 2000 was 1100 tonnes, including A S G M , not including combustion o f fossil fuels. This figure almost certainly underestimates  consumption from A S G M ,  especially i n Indonesia  (Veiga and Baker, 2004) and China. Regardless, much o f the 1100 tonnes o f mercury was probably consumed in China, and thus the number may provide an indication o f mercury  102  releases from other sources. Furthermore, the wide array o f additional sources for mercury makes it difficult to determine the exact source o f ambient mercury i n China. 5.1.3  Comparing Mercury Releases in China  The magnitude o f mercury sources from mining in China for 2001 is compared in Table 5.4 and Figure 5.1.  Table 5.4  Chinese Sources o f Mercury Releases Due to M i n i n g (2001) Source ASGM State-owned Coal Mines A S M Coal Mines A S M Mercury Mines State-owned G o l d Mines State-owned Mercury Mines Total  M e r c u r y Releases (tonnes) 238 176 127 28 20 19 601  State-owned  State-owned Mines  39.9%  Figure 5.1  China's Mercury Releases Due to M i n i n g  103  A S G M is the largest source o f mercury in China, along with the state-owned coal mining sector. The rejection o f whole ore amalgamation through the adoption o f alternative technology  could  dramatically reduce  mercury  releases.  However, the  effective  introduction o f alternative technology is not a trivial matter.  5.2  Alternative Technology  Introducing alternative technologies to economically marginal activities i n developing countries is hardly a new concept. Governments, N G O s , aid organizations and others have been doing this work for decades, especially i n agriculture.  Past efforts have often failed unless they met the following criteria: •  Economically beneficial - The technology must be inexpensive to operate and it must generate obvious financial benefits;  •  Simple - The technology must be easy to use and would ideally utilize readily available resources; and,  •  Expedient - The economic mineral must be efficiently recovered.  More directly, any new technology must be "fast, easy, and cheap" (Hinton et al, 2003a).  The first efforts  to address these issues were termed "Appropriate Technology."  Appropriate Technology is a curious term, with an ideological background and a politicized history. This section defines and explains "appropriate technology" and explains why "alternative technology" is used as a substitute i n this thesis.  Appropriate Technology refers to a philosophy o f life as much as to technology. It has its ideological basis i n the Gandhian Movement and Edward Schumacher's writings, such as "Small is Beautiful" (Schumacher, 1973). The term suggests that there are different technological options for solving problems and that some technologies may be more appropriate i n some situations than others. The counterpart to this is that there is technology that is not "appropriate".  104  In the 1970s and early 1980s Appropriate Technology was i n vogue, and a number o f books and articles were published on the topic, each with their own definition o f what exactly Appropriate Technology ( A T ) referred to. The list o f A T criteria in the "Appropriate Technology Sourcebook" by Darrow and Pam (1981), as listed below, is representative.  Appropriate Technology Criteria: 1) L o w i n capital costs; 2) Use local materials whenever possible; 3) Create jobs, employing local skills and labour; 4) A r e small enough i n scale to be affordable by a small group o f farmers; 5) Can be understood, controlled and maintained by villagers wherever possible, without a high level o f Western-style education; 6) Can be produced out o f a small metal-working shop, i f not in a village itself; 7) Suppose  that  people  can  and  will  work together  to  collectively  bring  improvements to their communities, recognizing that in most o f the world important decisions are made by groups rather than by individuals; 8) Involve decentralized renewable energy sources, such as wind power, solar energy, water power, methane gas, animal power, and pedal-power (such as i n that highly efficient machine, the bicycle); 9) Make technology understandable to the people who are using it and thus suggest ideas that could be used i n further innovations; 10) A r e flexible so that they can continues to be used or adapted to fit changing circumstances; 1 l ) D o not involve patents, royalties, consultant fees, import duties, shipping charges, or financial wizards; practical plans can be obtained free or at l o w cost and no further payments is involved.  A s can be seen from the seventh to the eleventh criteria, appropriate technology involved far more than simply using a technology that is most appropriate for the given situation. A more succinct definition, from the U . S . Congress's Office o f Technology Assessment,  105  defines A T as "being small scale, energy efficient, environmentally sound, labourintensive, and controlled by the local community" (Hazeltine and B u l l , 1999).  A T ' s popularity arose from the belief that i n order to alleviate poverty, groups concerned with development should focus on providing simple technology rather than expensive modern factories, dams, highways, and airports. A T could provide "goods, services, and jobs that w i l l not be provided any other way. N o company or organization w i l l be able to invest enough i n high-technology factories in developing countries to provide sufficient jobs" (Hazeltine and B u l l , 1999). In addition, A T was attractive to people in wealthy nations trying to simplify and lessen the environmental impact o f their lifestyle.  This apparently sensible approach to development was not without enemies. Leaders from developing nations resented the idea o f trying to modernize using technologies and equipment often perceived as outdated and primitive. D i d A T actually work toward national development, or did it i n fact discourage industrialization? While the ideology o f A T became widely accepted i n the 1970s and 1980s, it was often used as a way to justify exporting cheap and low technology goods from developed nations. The term quickly became overused, creating a dichotomy between "real appropriate technology", and "old fashioned/obsolete technology." Developing nations became increasingly frustrated with the term and the poor quality equipment they were receiving under the guise o f A T from various development programs. Often knowledge transfer was eschewed i n favour o f simply sending cheap  equipment,  without building the capacity to maintain the  equipment or supply spare parts. In effect, A T came to be associated with obsolete equipment. B y the early 1990s the term was badly enough regarded that the U N I D O eliminated the term in favour o f terms like "sustainable technologies" (Veiga, 2003). In this thesis the term 'alternative technology' is used as a substitute, with the aim o f capturing the flexibility and utility o f appropriate technology without its stigma.  "Alternative technology" is hardly a new term either. Jequier and Blanc (1983) defined it as follows: "the term used to describe new types of equipment or new forms which represent a viable alternative to the existing  'main-stream'  organisational technologies  of  106  today." Other terms with similar meanings  include "environmentally sound and  appropriate technology ( E S A T ) " for appropriate technology using renewable resources, and "intermediate technology," for a technology that stood halfway between traditional and modern technology.  For the purposes o f this work, "alternative technology" is: 1) Environmentally  and/or  socially  beneficial  -  it must  provide  concrete  improvements over the existing technology; 2) Economic - it must match the capital availability o f those who w i l l own and work with it and provide a reasonable return on investment; 3) Safe, with no major health risks; 4) Simple - the technology can be understood, and is attainable by the users; 5) Easy to maintain - users need to be able to afford spare parts or be able to repair the machine on their own; 6) Flexible enough to be able to handle changing circumstances;  "Sustainability" i n A S G M is contradictory, as an ore deposit is inherently finite, and thus not sustainable. However, communities that host A S G M  activities are potentially  sustainable, and small-scale miner organizations (companies, cooperatives, or whatever form they take) are potentially sustainable sources o f employment, materials, and income, i f they act responsibly enough to gain social licence to operate and are flexible enough to adjust to changing circumstances (Veiga et al, 2001).  A n y technical alternative must be thoroughly examined, pre-tested, and appropriately modified i f it is to be successfully transferred to miners and lead to more environmentally sound and socio-economically sustainable A S G M activity. 5.2.1  Sustainable Alternative ASGM  Technology  The test work above demonstrates that it is possible to get similar gold recoveries from a Knelson Concentrator / cyanidation circuit as from a mercury muller m i l l / cyanidation circuit, with far less mercury releases. A centrifugal concentrator was initially chosen for the alternative technology, as the miners were interested and the technology is relatively  107  efficient, and thus would provide a good indication o f the optimal recoveries possible using gravity. The miners were familiar with traditional gravity technologies such as sluice boxes, but were not interested i n using them, as they felt their mercury methods were more advanced.  Regardless,  Knelson Concentrators  may not necessarily  be the most  'sustainable'  alternate solution for A S G M miners using muller m i l l technology. A simpler gravity solution, such as a sluice box, j i g , or the Cleangold™ magnetic sluice, i n combination with cyanidation, may work almost as well. A s demonstrated in Figure 5.2, both mercury and gravity circuits fulfill a similar role: removing coarser, more liberated gold as cheaply and easily as possible before the more costly and time-consuming process o f cyanidation. 100000 I  —  —  1  10000  — •s «]  a |  J, il w>  1000  a  a 100  1  .a  io  I  -I  h Jigs  Spiral concentrators  1  1  Strokes and riffles  Amalgamation  1  1  1  Centrifugal Shaking tables Concentrators  '  1  Cyanidation  Figure 5.2 G o l d Particle Size Recovery Range (after Yannopoulos, 1991 and Priester et al, 1993) A centrifugal concentrator is likely to achieve higher recoveries than an  alternative  gravity method, as the centrifugal concentrators are more effective at recovering fine gold. However, the cyanidation process would likely pick up this fine gold in the next  108  step. Since the A S G M cyanidation processes are not especially efficient, recovering the fine gold in a gravity step would probably increase the overall recovery. For A S G M operations, as opposed to formal operations, this would probably be a small increase in revenues and might not have a fast enough payback to justify the added cost o f a centrifugal concentrator.  One o f the prime problems with centrifugal concentrators as alternative technology is that they are relatively complex to manufacture well. The main manufactures are located in Canada and thus concentrators are subject to import duties, and finding spare parts can be expensive and time-consuming. However, centrifugal concentrators tend to be robust, and many o f the wear parts, like drive belts, could easily be replaced locally. In comparison, muller mills are simple, inexpensive and manufactured locally. A s mentioned in section 2.3.1.1, a muller m i l l with a capacity o f 0.5 - 1.0 tonnes per hour costs around US$1,200, versus at least $US 10,000, not including duty or taxes, for a centrifugal concentrator with a similar capacity. A t least one Chinese company produces centrifuges; however, they are not widely accepted, are poorly manufactured, and are not as efficient as the main Canadian suppliers. Inexpensive, simpler centrifugal concentrators are also manufactured in Brazil and Zimbabwe.  One o f the main reasons that centrifugal concentrators might be appropriate is perception. Chinese A S G M  operators/owners  are well aware o f the alternate gravity methods  mentioned above, but distain them and consciously choose mercury methods instead. Sluices/jigs/spirals are seen as too simple and susceptible to theft, as the high-grade gold concentrate may not be secure. Centrifugal concentrators can be easily locked during operation and may be less susceptible to theft. In addition, centrifugal  centrifuges  represent a new technology, and thus have the potential to renew interest i n gravity methods. In other words, even i f centrifugal concentrators did not offer significantly better results than simpler gravity technologies, A S G M miners might be willing to accept switching from mercury to gravity methods  due the  perception that centrifugal  concentrators were a more modern, efficient technology, as well as reducing the need for mercury use.  109  Regardless, even operations that installed centrifugal concentrators would likely continue using mercury to some extent. The gravity concentrate is unlikely to be a high enough grade to proceed to direct smelting. The most efficient method o f further concentration is to m i x the gravity concentrate with mercury through barrel amalgamation. While this still involves mercury, using amalgamation on only the concentrates reduces by several orders of magnitude the amount o f mercury released. Veiga (2004b) reports that barrel amalgamation can achieve recoveries o f about 90%.  A key part o f making the centrifugal concentrator / cyanidation method more appropriate for Chinese A S G M is to try to integrate the muller mills as the primary comminution stage o f the circuit, without whole ore amalgamation, instead o f introducing ball mills. The miners are comfortable with the muller m i l l technology, and its inexpensiveness, local manufacture, and efficiency make it more sustainable than getting new ball mills manufactured i n other areas o f China. A key point in favour o f muller mills is that the entire process is visible; unlike ball or hammer mills, at no point is the ore hidden. This has proven a key concern in implementing new technologies i n Zimbabwe (Veiga, 2004b). It also reduces the capital costs o f installing a new gravity circuit.  A Belgian development assistance project i n Chile implemented an identical flow sheet, replacing a Chilean muller m i l l amalgamation centre with a Knelson / cyanidation circuit, while keeping the muller m i l l for comminution, but not amalgamation (see figure 5.3) (Dandois, 2000). Stamp mills may be another alternative; however, they are not manufactured in China, and are not an accepted technology.  The Cleangold magnetic sluice, which uses polymeric magnetic sheets, with the magnetic poles aliened normal to the direction o f the flow, inserted into an aluminium sluice box, offers another potential alternative technology. Magnetite or iron fillings, forms a corduroy-like bed on the sluice floor, which appears effective at recovering fine gold. Preliminary studies indicate recoveries similar to centrifugal concentrators for some ores (Gunson, 2003), with concentrate grades reaching 2854 g/t (Veiga and Gunson, 2004).  110  While the sluices are not manufactured locally, they are inexpensive, simple, and easy to maintain. Equipment to process 0.5-1.0 tonnes per hour would cost around $US500.  Figure 5.3  Muller M i l l / Centrifugal Concentrator, Chile (Davidson, 2001)  Alternatives to reduce mercury releases are plenty, including gravity, flotation and cyanidation methods. However, any attempt to replace mercury use must understand that amalgamation is often an extremely effective method and can be difficult to improve on. One key understanding that seems to have arisen is the need not to focus on eliminating mercury use, but on eliminating the amalgamation of whole ore and to promote the use of retorts. Attempts to ban amalgamation may reduce releases significantly, but would force other operators underground and eliminate the possibility of introducing more sustainable approaches. A better alternative is to target practices that lead to the most releases, such as whole ore amalgamation in muller mills in particular, and share practical alternatives with artisanal and small-scale miners.  ill  5.3  Technology Transfer  Transferring technology, even i f it is alternative technology, is a hugely complex task. Comparatively little resources have gone into A S G M technology transfer compared to agricultural or industrial technology transfer, as A S G M activities have often been marginalized, and involve fewer people with far less political clout. However, the issues that arise are quite similar.  The basic tenet o f technology transfer is that technology does exist, or technology can be readily developed, that is superior to the existing technologies being used by the people in the field. The challenge is how best to inform the end users that this technology exists, or can be developed, and to get them to accept the new technology and successfully implement it in their operations. Technology transfer immediately runs into a significant hurdle with its basic tenet; existing technologies have been honed for years (sometimes centuries) to local physical, economic and social conditions, and it can be difficult to prove or convince the users that the new technology is in fact better.  One example is the quimbalete, a traditional Andean amalgamation gold-processing technology that can metallurgically outperform newer gravity and cyanidation techniques. The quimbalete, while simple and cheap, also loses significant amounts o f mercury, and is extremely labour intensive. A n y attempts to replace quimbaletes must convince the users that the expense o f new equipment and the potential loss o f employment and tradition are outweighed by the improvements in their local health and environment and by increased productivity ( C A S M , 2002). A l l technologies have different costs and benefits and it is rare that the benefits o f a new technology are so overwhelmingly positive that it w i l l be universally accepted. N e w technologies often come with hidden or delayed costs, such as social disruption, overuse o f land, or long-term health effects.  A n y truly effective alternative technologies have to be developed i n close cooperation with artisanal and small-scale miners and researchers. Working i n isolation and bringing packaged solutions to the miners is unlikely to be successful, regardless o f how clever the research. It is well demonstrated that bottom-up measures, or programmes developed by  112  the people participating i n them, tend to be most effective and enduring (Hinton et al, 2003a).  A S G M encompasses an enormous diversity o f operations and communities. A sustainable alternative technology solution for one area might be entirely inappropriate for another, even nearby, area. For example, a solution for a primarily agricultural community with part-time miners may be significantly different than one for a migrant gold rush community. Careful consideration o f the local socio-economic conditions, as well as the technical problem, is paramount to a successful technology transfer. Technical assistance for A S G M should not simply be a downscale o f formal mining technology. A truly sustainable  alternative technology, i f it is effectively transferred,  should be self-  maintaining, and should encourage further innovation. Other A S G M operations should be able to see its effectiveness and work toward their own sustainable solutions. A n example of the difficulties involved with technology transfer can be seen from the international experience with A S G M processing centres. 5.3.1  AS GM Processing  Centres  Several previous models and projects, described i n brief below, have aimed to reduce A S G M mercury releases through the creation o f clean (or cleaner) processing centres. The thrust o f the concept was that individual, very small-scale processing operations are extremely difficult to effectively monitor, implement safety or environmental controls, or upgrade technologically. Building one central ore-processing centre i n an area, i n theory, allowed the creation o f a larger-scale, cleaner operation, although still small i n comparison to the formal mining industry. A central plant could be monitored to ensure health, safety, and environmental concerns are addressed, and could take advantage o f more expensive and complicated technologies, leading to higher recoveries. Miners would bring a concentrate or high-grade ore to the centre and either pay a fee for milling or simply sell their ore to the centre. The more organized nature o f processing centres could make them more attractive to investment, regulators, the legal system, and society, in essence allowing A S G M to become part o f the formal economy (Hinton et al, 2003a). In addition, the centres can act as distribution points for technical and safety information for A S G M .  113  Several processing centres or models have been conceived, including: •  U N I D O ' s Unit o f G o l d Extraction and Controlled Amalgamation ( U N E C A ) model, based on the Carhuachi Center in Venezuela. The U N E C A Center concept was to be implemented i n approximately six months, use special amalgamation plates and/or a sodium chloride electrolytic leaching process, and be built for approximately US$250,000. Miners would be charged approximately US$1 per kilo o f concentrate processed. However, centres were expected to run at a loss (Veiga and Beinhoff, 1997) and no U N E C A centres have been built.  •  Intermediate  Technology Development Group (ITDG), i n cooperation with the  National Miners' Association o f Zimbabwe ( N M A Z ) , built the Shamva M i n i n g Center in Zimbabwe, i n 1989. Acting as a central m i l l for approximately 200 miners, the centre process used a jaw crusher followed by a ball m i l l and a centrifugal concentrator. The concentrate was rolled i n an amalgamation barrel and then retorted. The tails o f both the centrifuge  and amalgamation barrel were subjected  to  cyanidation and the pregnant leach solution was precipitated with zinc shavings. In addition, the Center provided drilling and blasting services, ore  transportation,  technical support, and information on legal issues, geology and metallurgy and the selection and purchase o f equipment. Local miners were responsible for their own ore throughout the milling process, supervised by a plant manager. Miners paid - U S $ 6 per hour (~US$4/t) to use the plant and take away the gold recovered (on average ~5g/t). Tailings were reprocessed with cyanide by the plant to generate revenue (Hinton et al, 2003b; Simpson, 2004). Friction between N M A Z and I T D G caused the subsequent breakdown o f project (Simpson, 2004). •  The Agence de Cooperation au Developpement par les Sciences Et les Techniques, a Belgian development agency, set up an assistance project i n Chile that replaced a Chilean muller m i l l operation with a centrifugal concentrator / flotation circuit, using the muller mills as grinding mills i n the late 1990s. The project cost US$182,557 (Dandois, 2000), and has since closed.  114  Several issues can commonly arise from central processing centres. While locally effective in reducing mercury releases, these models were never cheap enough to become generally accepted among small-scale gold miners. M a n y o f these centres still used mercury i n the process, albeit losing far less mercury than the operations they replaced. Since these centres were static, they could only impact a small number o f miners. They also competed against local processing operations, and they were often not profitable. For processing centres to genuinely appeal to small-scale miners, they need to have incentives to change their existing methods. Without maintaining at least the existing profits, it would be hard to convince miners o f the utility in switching. Perhaps most importantly, all o f the above examples required significant capital investment and expert inputs from outside organizations. That all three were not imitated and are all closed is the best indication o f the limits o f this model.  The Global Mercury Project ( G M P ) , which has projects in Brazil, Indonesia, Laos, Sudan, Tanzania, and Zimbabwe is exploring a different model. Instead o f static centres, the G M P would build Transportable Demonstration Units, or T D U (Veiga, 2004b). These units  would  demonstrate a variety o f technical options  for gold  concentration,  amalgamation and retorting to miners; the miners themselves would be able to select what is affordable, appropriate and durable for their own operations. Being transportable, the T D U would be able to visit several areas and educate a far wider range o f miners than was possible with the static processing centres. Local processing centres would feel less threatened, as the T D U would not be a competing processing operation. Problems o f land tenure, services, mineral rights, etc., involved with processing centres would be avoided and the T D U would be able to easily change and adapt new pieces o f equipment used for demonstration. While the T D U would be dependant on aid money, it avoids many o f the short falls o f central processing centres and may be a more successful model for technology transfer to A S G M . However, for a large country such as China, for an idea like the T D U to be widely implemented would require the close cooperation o f government at all levels.  115  5.4  A S G M and Policy  Despite the serious negative impacts o f amalgamation and the presence o f real technical alternatives, few governments have implemented effective A S G M policies with any measure o f sustained success. Andrews-Speed et al (2003c) identifies three main barriers to the effective management and regulation o f A S M :  The first is a combination of political  opposition, vested interests and ineffective  government. A policy for small-scale mining can only be implemented if the interests of most or all relevant parties second  impediment  is the inadequate  are adequately  or inappropriate  effectively  addressed. The  nature  of  national  regulatory regimes for small-scale mines, which includes both the system of laws and regulations  and the institutional  structure.  The third obstacle is a lack of  financial resources to implement policies.  This reflects the situation i n China. Politically, many figures i n higher levels o f government simply see A S G M as a problem, and want to shut it down rather than create a viable framework within which it can exist. O n the other hand, local governments, who often depend on A S G M tax revenue and employment, are cautious about cooperating with any efforts that may potentially disrupt their income. Concerning regulations, the effort to simply ban mercury led to mines either continuing amalgamation illegally or convincing local governments to ignore the mercury ban and issue local permits. The policy and regulatory regime simply do not encourage honesty or the responsible use o f mercury. The lack o f financial resources to successfully implement policies is a combination o f the sheer scale o f China and the lack o f political w i l l to use tax dollars to address the issue. A n y effort to address the problems o f amalgamation i n A S G M must recognize these barriers and work toward overcoming them.  116  6  Limitations and Bias  The results o f this thesis were restricted by several limitations. These include: •  Language and Culture: The author, while generally functional i n Chinese, is hardly fluent. The interviews from the first trip to " G o l d Mountain" and the trips to Guangxi and Inner Mongolia were somewhat limited due to the lack o f an interpreter. However, the miners seemed more at ease without the presence o f interpreters, as an interpreter indicates wealth and/or government connections. This ease can be demonstrated by the fact that the closest and most fruitful relationship developed over the course o f this research was with the " G o l d Mountain" miners, where the initial relationship and trust was built without the presence o f an interpreter. Interviews, by necessity, were often informal and incomplete.  •  Access to Government Information: The Chinese government probably has various reports on A S G M and mercury that would not be available to the author.  •  Government: This research was not undertaken through official government or academic channels, primarily since such approval, i f available, would have been costly and time consuming. Since amalgamation is largely illegal, miners were often cautious about discussing their practices, and site visit locations and interviewees often were obscured.  •  Medical Training: A lack o f medical expertise available restricted the ability to effectively judge the health impact o f mercury use by A S G M miners.  •  Equipment: The financial and geographical logistics o f the site studies were such that it was impossible to take equipment for onsite mercury or gold analyses, or to keep biological samples for later testing.  •  H g E X : H g E X was validated for the A m a z o n and for northern Canada. It may not be relevant i n the sites examined in China.  •  Test Samples: The samples sent for test work were clearly from different ore bodies, which greatly restricted the ability to compare between results. In addition, the " G o l d Mountain" miners collected the samples, making it difficult to verify that the samples were representative.  117  A simple method o f categorizing systematic research errors is to classify them i n two general classes: selection and observation bias (Hennekens and Buring, 1987). Due in part to the above limitations the following bias are noted: •  Selection Bias o  Site Visit Regions: Site visits were chosen to represent several different regions o f China, however, a limitation was that all o f the sites had to be reasonably accessible by public transportation. A l l sites visited were less than one day's travel from an urban center, a necessity as many rural village hotels are barred from accepting foreigners. This excluded A S G M sites in the most remote areas or in government restricted areas. It may be reasonable to assume that the more remote areas practice less safe processing  methods  than  in  areas  relatively accessible  to  urban  commercial and educational centers. o  Site Visits and Interviews: Mines and processing centers could only be studied i f the miners were willing to cooperate with the research. Outright illegal miners had little incentive to agree to site visits or interviews, and these miners' operations may have been less safe than operations willing to cooperate with the author.  o  Test W o r k Samples: The test work indicates that the samples my not have been representative. The high gold grade and slow leaching nature o f the feed sample, and the high gold grade and mercury content o f the muller m i l l tailing sample, indicate that they may have come from ores the miners were having difficulty processing. These samples may have exaggerated both the gold grades and the difficulty o f processing o f ores in " G o l d Mountain".  •  Observation Bias o  Interviewer Bias ( A ) , Observing for Indications o f Mercury Poisoning: While the thesis indicates a l o w number o f mercury poisonings, this could be due more to a lack o f medical knowledge than an actual absence o f illness. Systematic testing by skilled personnel could reveal far more  118  extensive mercury related health impacts. Only the most extreme cases could be observed. o  Interviewer Bias (B), Observing for Mercury Bioaccumulation: The lack of mercury analysis equipment meant it was impossible to demonstrate bioaccumulation i n local aquaculture. Without verification, the bias was that bioaccumulation was not a serious factor.  o  Interviewer Bias (C), Research Cooperation with Miners: Working with A S G M miners directly, instead o f working through official  channels,  tended to bias the author i n favour o f the miners and local communities. M u c h o f the research depended entirely on the good w i l l o f local government officials and miners. M a n y interview questions dealt with sensitive issues for the miners and the answers were not necessarily honest, but were still valuable. o  Recall Bias, Miner Estimates: The lack o f assay equipment (or even scales) meant that miners often needed to be taken at their word for their estimates o f grades and recoveries. Based on some discrepancies outlined in Chapters Three and Four, it is assumed that miners exaggerate their recovery rates and mislead with regard to their gold grades and mercury use.  o  Misclassification Bias, Mercury Source: A s mentioned i n Chapter Five, China hosts many industries that emit or release mercury into the environment. A n y i l l effects due to mercury may not necessarily be due to ASGM.  These biases would have been difficult to overcome during the course o f this research, primarily due to the lack o f initial study on the topic and due to limited funds. However, additional research could easily overcome these limitations.  119  7  Areas for Additional Research  Several gaps i n knowledge or practice were identified, including: •  Great uncertainty about the actual gold production of, income generated by, and number o f people employed i n A S G M in China.  •  A lack o f understanding regarding many details about the legal status and tax structure o f A S G M in China.  •  A n incomplete picture o f the role o f women and children i n A S G M i n China.  •  Uncertainty regarding the risk o f mercury vapour poisoning due to the smelting o f zinc strips following amalgamation and cyanidation.  •  Uncertainty about the effect o f cyanidation on amalgamation tailings. This preliminary work w i l l be followed up by further research at the University o f British Columbia under the direction o f Dr. Marcello Veiga.  •  Uncertainty about the amount o f mercury that reports to the zinc strips versus the final tailings following the cyanidation o f amalgamation tailings.  •  A need for case studies to verify  the feasibility o f replacing whole ore  amalgamation o f hard rock ores with gravity concentration. •  A poor understanding o f the effectiveness o f muller mills for comminution versus more standard methods o f hammer, ball, or rod mills.  •  A gap i n the understanding o f mercury releases from industrial sources i n China.  Toward the end o f addressing many o f these gaps, the following recommendations are suggested: •  A thorough socio-economic baseline study o f at least one A S G M community should be undertaken, using a method such as the Department for International Development's (DFID) Sustainable Livelihoods approach (DFID, 2001).  •  A proper environmental impact study o f the behaviour o f mercury in the environment due to A S G M should be undertaken in at least one area.  •  A comprehensive epidemiological study regarding exposure to mercury and the resulting health impacts on the A S G M population should be completed i n at least one community.  120  •  Following the three studies listed above, the data obtained should be used to validate H g E X for China.  •  A n organization should be built to coordinate these and more studies and to share the  information learned with miners, researchers,  policy makers, and  the  international community.  To this end, the author has been instrumental in assisting in the creation o f an organization called the Communities and Small-Scale M i n i n g Regional Network in China ( C A S M - C h i n a ) . C A S M - C h i n a aims to bring together a wide range o f people involved in artisanal and small-scale mining i n China, within the context o f poverty alleviation and sustainable communities (See Appendix I for further details).  In addition, one o f the initial aims o f this research was to discover i f Chinese methods o f dealing with these environmental and health problems could be applicable to other parts of the world, or i f techniques developed outside o f the P R C could be used by the Chinese. The " G o l d Mountain" retort has already been successfully introduced into Colombia (Sandoval, 2003), Venezuela (Veiga and Gunson, 2004), and Laos (Veiga, 2004a), and has been shared with the international community through two papers (Hinton et al, 2003; Gunson and Veiga, 2004). Centrifugal concentrators were introduced to the  ASGM  community o f " G o l d Mountain" in 2002. China also provides numerous examples o f integrating A S M with a diversified rural economy; " G o l d Mountain" meshes specialty agricultural crops, grain crops, tree farming, small-scale manufacturing, gold mining, iron mining, sand and gravel operations, and dimension stone quarries. C A S M - C h i n a can help to further facilitate the exchange o f best practices around the world.  121  8  Conclusion  The interviews, field studies, and test work undertaken for this thesis lead to the following main results and conclusions: •  A S G M i n China employs 463,000 A S G M miners producing around 61 tonnes o f  gold, i n regions all over China, with almost 3.5 million dependants. A S G M released 237 to 652 tonnes o f mercury in 2001 and is easily one o f the top sources o f mercury releases in China. A t the low range o f the estimate, A S G M contributes about 40% o f the mercury releases due to mining, and whole ore amalgamation i n muller mills may be responsible for up to 70% o f these mercury releases. A t every site and region visited, A S G M operations used mercury, often followed by cyanidation. The H g E X expert system tool was used to demonstrate the potential impact o f mercury contamination from A S G M and to indicate that China has a moderate acceptance o f amalgamation practices. •  The " G o l d Mountain" case study verified that A S G M  i n China could release  significant amounts o f mercury, with " G o l d Mountain" alone releasing at least one and a half tonnes o f mercury per annum. Mercury use represented only 2.8 % o f the overall gold production cost, and the ratio o f mercury lost per unit o f gold recovered for muller mills is from 14:1 to 20:1. The " G o l d Mountain" retort was described, representing a simple and inexpensive technology that has the potential to reduce mercury exposure to miners around the world. •  The " G o l d Mountain test program further verified the high levels o f mercury being  released from " G o l d Mountain's" processing centres, with the muller m i l l tailings mercury concentration reaching 2224 ppm, and the cyanidation tailings reaching 285 ppm mercury, from a background mercury concentration, as indicated by the feed ore, o f only 0.78 ppm. Test work completed on the feed sample, grading about 43 g/t gold, indicated that around 40% o f the gold was recoverable by gravity methods and that the leaching rate o f the ore is extremely slow, perhaps due to the high levels o f copper (0.44%) and tellurium (13.71 ppm). The test work demonstrated  that gravity methods could be  introduced to replace whole ore amalgamation, and that increased comminution would help the miners achieve higher recoveries, although amalgamation o f gravity concentrates may still be necessary to produce a saleable product for the miners. The muller m i l l  122  tailings sample, with a gold grade o f 38.1 g/t, indicated that amalgamation had not effectively recovered gold from the initial ore, especially as 4 3 % o f the gold i n the tailings was recovered, 30% i n the first pass without additional grinding. •  The health impacts o f mercury releases are o f key concern. Mercury vapour  pollution, despite the use o f retorts, is o f primary concern, as demonstrated by a miller who stated that he had been diagnosed with health problems due to mercury exposure. The lower mercury concentration in the cyanidation tailings indicated that much o f the mercury from the muller m i l l is removed by cyanidation, to be volatilized during the zinc strip smelting process. The potential for mercury bioaccumulation exists and should be further investigated; the mercury solubility tests indicate that cyanidation, following whole ore amalgamation, may increase the solubility o f the mercury i n the tailings. •  A n y attempt to address mercury pollution from A S G M must come to terms with the  complex socio-economic and political framework i n which A S G M i n China operates. A S G M operations provide desperately needed employment and tax revenue in remote areas with few alternative economic activities but essentially lacks any formal or informal support from domestic or international organizations. •  Effective policies must be implemented in China to encourage multi-stakeholder  cooperation, and laws and regulations with which A S G M is reasonably able to comply must also be implemented. Building an effective policy toward minimizing mercury releases from A S G M would require significant political support at high levels, effective cooperation with local governments, and genuine dialogue between artisanal and smallscale miners, local communities and governments, and experts. A n effective policy would require  a  multi-pronged approach  to  the  issue,  involving  regulatory initiatives,  organization, education and training, and financial support.  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Opinion within the country is sharply divided between those who see A S M activity as harmful and unnecessary and those who see it as essential for local development. This meeting broke new ground by including discussions that encompassed a full range o f A S M issues. During the course o f the meeting 43 participants from 24 agencies met together and discussed how an effective network w i l l be organized and what goals can be achieved in China's complex and often sensitive A S M sector. These agencies included: •  • • • • • •  Seven departments i n the Ministry o f Land and Mineral Resources (China M i n i n g Association, Department o f Mineral Exploitation, Senior Consultancy Center, Information Center, Center o f Land and Mineral Legal Affairs, Academy o f China Geological Environmental Monitoring, and the Academy o f Land Resources Economics); The State Safety Production Supervisory Bureau; T w o institutes i n the Chinese Academy o f Sciences (the Institute o f Geographic Sciences and Natural Resources Research and the Center for Eco-Environment), One institute i n the Chinese Academy o f Social Sciences (the Institute o f Quantitative Economy and Technical Economy); Four universities (China Renmin University, Shanxi University o f Finance and Economy, Chongqing University, Liaoning University o f Technology at Fuxin); Three provincial agencies (Bureaus o f Land and Mineral Administration o f Yunnan, Chongqing, Shanxi), and; T w o local agencies (Shahe City in Hebei province and Shanghang county in Fujian province).  Representatives from the Canadian Embassy, R i o Tinto, and B H P B i l l i t i o n attended the second reception dinner, as well as Dr. Philip Andrews-Speed, from the University o f Dundee and A J Gunson, from the University o f British Columbia. In addition to summarizing the meeting, this report details C A S M - C h i n a ' s organization, budget, goals and work plan for 2004. The total expense for hosting the meeting was under budget at U S D $7,786.29. The meeting marks a promising start for the network, and was well received by the participants, who were eager for the opportunity to discuss the role o f A S M in China.  136  CASM-China  Background  Following C A S M ' s September 2003 Annual Meeting in Elmina, Ghana, Shen L e i , A J Gunson, and Philip Andrews-Speed submitted a proposal to create C A S M - C h i n a . In November 2003 C A S M accepted the proposal and i n December 2003 provided C A S M China with the terms o f reference and the initial payments. Formal planning for the inaugural meeting began in November 2003 under direction o f the organizing committee, composed o f the initial proponents.  Meeting Agenda There were three main goals for C A S M - C h i n a ' s inaugural meeting: • • •  T o bring together and form a network o f a wide range o f A S M experts and government officials; T o design a practical organizational structure for C A S M - C h i n a ; and To build an initial work plan for C A S M - C h i n a .  researchers,  The agenda was set by the organizing committee and was intended to provide plenty o f time for the participants to meet each other and discuss informally the issues raised during the meeting. Table 1:  Program of Events  C A S M - C h i n a Inaugural Meeting Program of Events 5 January 2004 Registration 14:00 Introductions 16:00 Welcome Dinner 18:30 th  6 January 2004 A n overview o f A S M i n China (SL) 08:30 A n overview o f A S M and the international experience ( P A S ) 09:30 A n introduction to C A S M and the concept o f sustainable A S M 10.30 communities ( A J G ) Questions and discussion 11:30 Lunch 12:00 Inaugural Business Meeting for C A S M - C h i n a 14:00 Dinner with international stakeholders 18.30 th  7 January 2004 Final wrap-up session 8:30 Closing 11:30 th  137  Meeting Summary Monday, January 5, 2004 The meeting began at 4 : 0 0 P M at the Beijing Foreign Experts Building, i n northern Beijing. After a brief introduction by Shen L e i , all o f the participants introduced themselves i n turn, explained their experience with A S M , and described what they expected to get out o f the meeting. A s many o f the participants were not familiar with each other, it was important to provide adequate time to get to know one another. This format is unusual for China, where often only the highest-ranking people present are given time to speak. Following introductions, the participants met informally over dinner. After dinner, the organizers met with participants with three Chinese A S M officials with some authority to discuss the potential roles o f C A S M - C h i n a Tuesday, January 6, 2004 A t 8:30 A M the meeting reconvened for three presentations. Shen L e i presented on the overall state o f A S M in China. He reviewed the diversity and scale o f Chinese A S M , the recent history and government policies toward A S M , and the positive and negative impacts o f A S M i n China. Philip Andrews-Speed discussed the overall state o f A S M around the world. He reviewed changes i n the international community's approach toward A S M and key current questions facing policy makers and development agencies with regard to A S M . He touched on characteristics distinguishing A S M from formal mining, the costs and benefits o f A S M , A S M government policy internationally and the difficulties o f effective A S M policies, and methods by which A S M policies could be improved. A J Gunson presented on C A S M ' s structure, vision, role, and activities. H e stressed the importance o f using A S M as a tool for poverty alleviation on the road toward more sustainable communities. He then discussed the potential for C A S M to cooperate with C A S M - C h i n a and a possible structure and role for C A S M - C h i n a . Following an informal lunch, the meeting resumed with a discussion o f the costs and benefits o f A S M i n China. Participants noted that the A S M debate i n China encompassed a wide range o f topics including safety and health, environmental protection, industrial distribution, and rural poverty reduction. They also commented that the Chinese media and government usually only focused on the negative aspects o f A S M in China. W i t h a view to the broader issues, participants discussed current A S M policies i n China and the potential for change. One main issue discussed was the legal definition o f small-scale mining i n China and its legal implications regarding mineral resource law. In particular, participants were concerned about creating a clear boundary between formal large-scale mining and A S M . Participants recognized that a new national policy toward A S M is vitally necessary. Some participants argued that i n the future the central government cannot continue to close small-scale mines without providing any compensation for the  138  miners. In addition, the relationship o f poverty reduction with A S M and health, safety and environment training were discussed. After the discussion the participants reconvened for a more formal dinner with representatives from the Canadian Embassy, B H P B i l l i t o n , and R i o Tinto. The international participants expressed great interest i n the situation o f A S M i n China and looked forward to cooperating more with C A S M - C h i n a i n the future. Following the meal, the organizers met with four A S M officials from rural communities to discuss the role and structure o f C A S M - C h i n a and potential for future C A S M - C h i n a activities and projects. Wednesday, January 7, 2004 A t 8 : 3 0 A M the meeting continued with a discussion o f the future structure and role o f C A S M - C h i n a . Participants fully recognized the importance and necessity o f creating a multidisciplinary network approach to A S M in China. The importance o f formalizing C A S M - C h i n a and registering officially was stressed. Registering C A S M - C h i n a independently was perceived as time-consuming and difficult. Not registering i n some capacity is illegal. It was decided that the best option was to give C A S M - C h i n a a home within the China M i n i n g Association, which has a A S M department. The importance was stressed o f using C A S M - C h i n a ' s webpage for sharing both Chinese and international reports and papers on A S M . A n online discussion forum was also deemed important. Participants recommended that C A S M - C h i n a cooperate with the China M i n i n g Association and a county level government to host a local meeting with a wide range o f stakeholders to discuss the role o f A S M and the potential for using A S M as a vehicle toward poverty reduction and more sustainable communities. Participants also decided to both widen the C A S M - C h i n a network's membership nationally and deepen C A S M - C h i n a locally. Shen L e i thanked the participants for their involvement and hard work. Philip Andrews-Speed thanked Shen L e i and his assistance for organizing the meeting and making it a success before closing the meeting.  139  Key Meeting Achievements Over the course of the CASM-China Inaugural Meeting the following main results were achieved: •  •  The participants acknowledge as timely and of key importance the establishment of the CASM-China Regional Network. A l l participants fully recognized the necessity of further study on the issues of small-scale mining in China; while China's smallscale mining faces great challenges, it holds huge potential. Participants recommend that CASM-China become a legal organization under the China Mining Association (CMA). The C M A has broad and direct links with local small-scale miners and is closely involved with the administration and research on A S M in China. Further discussions with the C M A are required to formalize the details.  •  Fu Mingke, previous Director General of Department of Ministry Exploitation in Ministry of Geology and Mineral Resources (now renamed the Ministry of Land and Resources), recommended that Shen Lei be appointed as the Director of the Small Scale Mines Committee in the China Mining Association (CMA) after CASM-China is linked with the C M A .  •  The Senior Consultancy Center and the Center of Land and Mineral Legal Affairs, both in the Department of Land and Resources, also expressed interest in hosting CASM-China. While it was recognized that Chinese government officials and experts had made many great efforts to study and resolve A S M issues and done lots of studies on China's small-scale mines, there is still much work to be done. Participants recognized the importance of cooperating with international organizations such as the World Bank, UNIDO, and the ILO, both in order to share China's experience with other nations and to learn from the international experience. Participants recognized that of the many issues challenging Chinese A S M , the issues of regularization, environmental protection, health and safety and poverty alleviation should be given priority in future action plans.  •  •  CASM-China  Work Plan 2004  Based on the outcome of the Inaugural Meeting, a work plan and budget for the rest of 2004 is shown in Table 2 on the next page. This work plan includes; formalizing C A S M China, developing the Chinese-language web-based knowledge center, hosting local stakeholder meetings, and formalizing a national policy paper. In early February 2004, CASM-China will initiate the work plan, starting with the formalization of CASM-China under the China Mining Association.  140  Table 2: CASM-China Activity  Work Plan and Budget 2004  Details  Budget Projected (USD)  Inaugural Meeting CASM-China Formalization  Held January 5-7, 2004  Webpage Development  Local C A S M China Meeting  • Translate and make available key Chinese and international A S M legal and policy documents • Setup a discussion forum to share ideas and link agencies and individuals together • Co-host two pilot multi-stakeholder meetings in A S M counties with the C M A  Expand Network Nationally  • Report meeting results back to C A S M China Meeting participants are to reach out to their counterparts in A S M areas unrepresented at the meeting  Expand Network Locally  Rural meeting participants are to reach out in their communities to inform and involve other A S M stake-holders  C A S M Annual Meeting  Send at least one CASM-China representative to the 2004 C A S M Annual Meeting to report on CASM-China's activities Write a policy paper on A S M , poverty reduction, and sustainable communities to be presented to the Chinese State Council • Approach the China Science Foundation for cooperation studying the impact on communities of A S M coal mine closure and the potential for alternative sources of income • Approach the ILO and the State Safety Production Supervising Bureau for cooperation on a pilot mine safety project • Approach UNIDO and the Chinese Academy of Science for cooperation on a pilot mercury reduction project Begin planning and fund raising for the second annual meeting of CASM-China International money transfer fees, photocopying costs, and phone fees.  National Policy Paper Projects  CASM-China 2005 Meeting Transaction Costs Total  Set up CASM-China as a department under the China Mining Association (CMA)  Actual (USD)  7,786.29 In-kind contribution from the C M A 1000.00 500.00 3,000.00 + local county and C M A In-kind contribution from participants In-kind contribution from participants 1,500.00  500.00  100.00  100.00  100.00 300.00 213.71 7,213.71  7,786.29  141  Figure 1: CASM-China Inaugural Meeting  Summary C A S M - C h i n a ' s Inaugural Meeting marks a promising start for the organization. Participants from around China were successfully brought together to discuss A S M i n the context o f poverty reduction and sustainability. A plan to formalize C A S M - C h i n a under the China M i n i n g Association was developed. A s detailed i n the work plan, much work remains to be done, including registering the organization, developing the webpage, holding a pilot local A S M stakeholder meeting, expanding and deepening the network and investigating potential projects.  142  

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