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Comparative mineralogical study of base metal mine tailings, with various sulfide contents, subjected.. 1996

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C O M P A R A T I V E M I N E R A L O G I C A L STUDY O F B A S E M E T A L M I N E TAILINGS, W I T H VARIOUS SULFIDE C O N T E N T S , S U B J E C T E D T O L A B O R A T O R Y C O L U M N OXIDATION A N D FIELD L Y S I M E T E R TESTS, C O P P E R CLIFF, O N T A R I O . by SHANNON C. SHAW B.Sc. Honours (Geological Sciences and Chemistry), Queen's University, Kingston, Ontario, 1994 A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE in THE FACULTY OF GRADUATE STUDIES (Department of Earth and Ocean Sciences) We accept this thesis as conforming to the required standard THE UNIVERSITY OF BRITISH COLUMBIA October, 1996 ©Shannon C. Shaw, 1996 in presenting this thesis in partial fulfilment of the requirements for an advanced degree at the University of British Columbia, I agree that the Library shall make it freely available for reference and study. I further agree that permission for extensive copying of this thesis for scholarly purposes may be granted by the head of my department or by his or her representatives. It is understood that copying or publication of this thesis for financial gain shall not be allowed without my written permission. Department of &)>y\L Q(JL£LT\ &>U&\U$ The University of British Columbia Vancouver, Canada Date Qjrvh£r 7 \<\% DE-6 (2/88) ii ABSTRACT Since 1993, Inco Ltd. has been investigating the possiblity of using a flotation-derived low-sulfide tailings as a means of providing a potentially inactive cover and dam construction material for their Copper Cliff tailings area. The investigation involves open-air field lysimeter and laboratory oxidation column tests of a low-sulfide tailings product produced by the Clarabelle mill; as well as, the evaluation of the concurrent alteration of two tailings products, a main tailings (1.0 wt. % S), and a total tailings product (2.5 wt. % S), to provide comparisons of oxidation rates and the geochemical evolutions that accompany the sulfide-mineral oxidation in the different sulfide-bearing tailings. A pyrrhotite-rich tailings (approximately 14 wt. % S) was also subjected to oxidation in the laboratory columns for the same period of time and was also examined for comparison. This project was undertaken to identify the solid phases that are the primary sources of potential or known contaminants, and solid phases that provide potentially acid-neutralizing capacity to the tailings, as well as to identify secondary precipitates that serve to control the pore-water concentrations of dissolved ions in the various tailings types. The analytical methods employed to achieve these objectives include powder x-ray diffractometry, optical and scanning electron microscopy, energy dispersion spectroscopy and multi-element x-ray mapping techniques, electron probe microanalysis, and Debye-Scherrer x-ray film methods. In these tailings, the sulfide mineral of primary concern with respect to acid generation is pyrrhotite. The oxidation of pyrrhotite is marked by replacement with iron oxyhydroxides, including goethite and lepidocrocite, native sulfur, ferric iron sulfates, and covellite. Nickeliferous pyrrhotite is the primary source of pore-water nickel, with minor contributions from the oxidation of pentlandite and nickeliferous slag particles. Secondary goethite detected in the saturated zone of the tailings contains more iii nickel than the goethite from the unsaturated zone of the tailings and is the primary "sink" for dissolved nickel. Pentlandite has oxidized to various degrees in the tailings and is demarcated by replacement with iron oxyhydroxides. The oxidation of chalcopyrite is also evident contributing to pore-water concentrations of dissolved copper. Alteration is most commonly seen as dissolution and subsequent precipitation of secondary covellite, as well as replacement by iron oxyhydroxides. Slag particles, although volumetrically of less importance than the sulfides, may be a source of metal contamination including Ni, Cu, Co, and Cr. The oxidation of slag particles in the tailings is evident and is most intense in the total tailings resulting in the formation of secondary covellite and iron oxyhydroxides. Other secondary phases detected in the tailings include gypsum, jarosite, a venniculite-type clay mineral, and montmorillonite. The venniculite, and most likely the montmorillonite, are products of biotite alteration which poses the greatest potential for acid neutralization. Plagioclase is another source of neutralization potential in the tailings and shows some evidence of dissolution. The different tailings types show varying and progressive degrees of oxidation correlative with their specific sulfur contents. The degree of oxidation is determined by the relative extent to which the sulfides have reacted as well as the maximum depth to which oxidation is evident in the tailings. The low sulfur tailings (0.4 wt. % S), show the least degree of oxidation, the main tailings (1.0 wt. % S), show alteration intermediate between the low sulfur tailings and the total tailings (2.5 wt. % S), which have reacted the most. Goethite, gypsum, and jarosite, which are present in abundance in the pyrrhotite-rich tailings (14 wt. % S), have formed as secondary cements which, to all appearances, have impeded the oxidation occuring in the pyrrhotite-rich tailings column. The column tests indicate much higher degrees of oxidation and sharper demarcation boundaries between the oxidized and the unoxidized tailings. More pronounced differences among the three chemically different tailings are seen in the column samples than in the field lysimeters, and pyrrhotite in the tailings from the columns also show "leached" textures not seen in the field lysimeters. IV T A B L E O F C O N T E N T S Page Abstract ii Table of Contents iv List of Tables vii List of Figures viii A C K N O W L E D G M E N T S xii 1.0 A C I D I C D R A I N A G E F R O M M I N E W A S T E 1 1.1 Acid Generation 1 1.1.1 Pyrite oxidation 2 1.1.2 Pyrrhotite oxidation 4 1.2 Acid Neutralization 5 1.3 Metal Loading 7 1.4 Preventative Techniques 7 1.4.1 Underwater disposal 1 1.4.2 Wetland treatment system 8 1.4.3 Neutralization by alkaline materials 8 1.4.4 Inhibition of iron-oxidizing bacteria 9 1.4.5 Microencapsulation techniques 9 1.4.6 Capping techniques 9 2.0 INCO'S C O P P E R C L I F F T A I L I N G S : DESCRIPTION A N D C L O S U R E P L A N 11 2.1 Copper Cliff Tailings Basin 11 2.2 Closure Options 15 2.2.1 Option 1 15 2.2.2 Option 2 15 2.2.3 Option 3 16 2.2.4 Option 4 16 3.0 L O W S U L F U R T A I L I N G S : P R O D U C T I O N A N D INITIAL T E S T I N G 18 3.1 Production of Low Sulfur Tailings 18 3.2 Laboratory Based Tests 18 3.2.1 Acid Base Accounting tests 19 3.2.2 Column oxidation experiments 20 3.3 Field Bases Tests 24 3.3.1 Field lysi meter test pits 24 4.0 S A M P L E C O L L E C T I O N A N D P R E P A R A T I O N 26 4.1 Sample Collection 26 4.2 Sample Preparation 27 V 5.0 QUALITATIVE ANALYSIS: MINERAL IDENTIFICATION AND TEXTURAL 29 CHARACTERIZATION OF THE LOW SULFUR TAILING, MAIN TAILINGS, AND T O T A L TAILINGS 5.1 Powder X-ray Diffractometry 30 5.1.1 Field lysimeter test pits 30 5.1.2 Laboratory oxidation columns 34 5.2 Petrography 38 5.2.1 Identification of primary minerals 38 5.2.2 Characterization of silicate alteration 44 5.2.3 Characterization of sulfide oxidation 44 5.2.4 Characterization of slag particle alteration 65 5.3 Chapter Summary r 6.0 QUALITATIVE ANALYSIS: MINERAL IDENTIFICATION AND TEXTURAL 72 CHARACTERIZATION OF THE PYRRHOTITE-RICH TAILINGS 6.1 Powder X-ray Diffractometry 72 6.2 Petrography 73 6.2.1 Identification of primary minerals 6.2.2 Characterization of sulfide alteration 76 6.3 Chapter Summary 77 7.0 QUANTITATIVE ANALYSIS AND IMAGING OF THE LOW SULFUR TAILINGS, 79 MAIN TAILINGS, AND TOTAL TAILINGS 7.1 Quantitative Analysis of Unaltered Minerals 80 7.1.1 Silicates 80 7.1.2 Oxides 94 7.1.3 Sulfides 100 7.2 Quantitative Analysis and Imaging of Altered Minerals 102 7.2.1 Silicates 102 7.2.2 Sulfides 107 7.2.3 Slag particles 163 7.3 Chapter Summary 177 8.0 CONCLUSIONS 180 9.0 REFERENCES 186 APPENDIX A Mining History and Geological History of the Sudbury Igneous Complex 192 A . l The Geological History of the Sudbury Area 193 A. 1.1 Exploration and development 193 A. 1.2 The geological debate 196 vi APPENDIX B Some Interesting Facts about Nickel and Copper: the two metals of 204 primary concern in the Copper Cliff tailings B . l Nickel 205 B.l.l The history of nickel 205 B.l.2 Nickel toxicity 205 B.l.3 Nickel's role in everyday life 206 B. 2 Copper 207 B. 2.1 The history of copper 207 B.2.2 Copper toxicity 208 B. 2.3 Copper's role in everyday life 209 APPENDIX C Megascopic Characterization of the Field Lysimeter and Laboratory 210 Column Tailings C. l Field Lysimeter Test Pit Samples 211 C. 1.1 LST-1: low sulfur tailings (0.4 wt. % S), tailings surface 211 was dry when sampled C.l.2 LST-2: low sulfur tailings (0.4 wt. %S), tailings surface 211 was wet when sampled C.l.3 K4T-1: main tailings (1.0 wt. %S), tailings surface 212 was dry when sampled C.l.4 MT-2: main tailings (1.0 wt. % S), tailings surface 213 was wet when sampled C.l.5 TT-1: total tailings (2.5 wt. % S), tailings surface 213 was dry when sampled C.l.6 TT-2: total tailings (2.5 wt. % S), tailings surface 214 was wet when sampled C.2 Laboratory oxidation Column Samples 215 C.l. 7 LST-3: low sulfur tailings (0.4wt.%S) 215 C.l.8 MT-3: main tailings (0.4wt.%S) 215 C.l.9 TT-3: total tailings (0.4 wt. % S) 216 C.3 Munsell Notation 216 APPENDIX D Mineralogical modal abundance approximations 217 V l l LIST OF TABLES Page 2.1 Minerals reported in the Sudbury Igneous Complex 13 3.1 Bulk chemical analysis of the three tailings types prior to deposition in the field 22 lysimeters and oxidation columns 3.2 Sulfide oxidation rates for the three field lysimeters 25 5.1 Sulfide alteration index 47 5.2 Slag alteration index 65 5.3 Slag alteration indices for the oxidized zones of the three tailings types in the lysimeters 66 and the columns 7.1 Electron probe microanalysis results for plagioclase 81 7.2 Electron probe microanalysis results for amphiboles 82 7.3 Electron probe microanalysis results for biotite 86 7.4 Electron probe microanalysis results for chlorite 89 7.5 Electron probe microanalysis results for pyroxenes 92 7.6 Electron probe microanalysis results for magnetite 95 7.7 Electron probe microanalysis results for ilmenite 97 7.8 Electron probe microanalysis results for pyrrhotite 101 7.9 Electron probe microanalysis results for pentlandite 103 7.10 Approximate formula for altered biotite from the total tailings 104 Appendix C C - l Depth profile of the Munsell soil colour assignments in the low sulfur tailings lysimeter, 211 core # 1 C-2 Depth profile of the Munsell soil colour assignments in the low sulfur tailings lysimeter, 212 core #2 C-3 Depth profile of the Munsell soil colour assignments in the main tailings lysimeter, 212 core # 1 C-4 Depth profile of the Munsell soil colour assignments in the main tailings lysimeter, 213 core #2 C-5 Depth profile of the Munsell soil colour assignments in the total tailings lysimeter, 214 core # 1 C-6 Depth profile of the Munsell soil colour assignments in the total tailings lysimeter, 214 core #2 C-7 Depth profile of the Munsell soil colour assignments in the low sulfur tailings column 215 C-8 Depth profile of the Munsell soil colour assignments in the main tailings column 215 C-9 Depth profile of the Munsell soil colour assignments in the total tailings column 216 Appendix D D - l Mineralogical modal abundance estimations for samples from the three field lysimeters 218 D-2 Mineralogical modal abundance estimations for samples from the four oxidation columns 220 viii LIST OF FIGURES Page 2.1 Map of the Copper Cliff tailings area 12 3.1 Net neutralization potential versus weight percent sulfur for the three tailings types 20 3.2 Schematic representation of the laboratory column oxidation experiments 21 3.3 Cumulative rainfall versus pH, sulfate concentration, iron concentration, and 23 nickel concentration for the three tailings types in the oxidation columns 4.1 Sample locations in the field lysimeter test pits 26 4.2 Schematic representation of sampling the laboratory oxidation column 27 5.1 Powder x-ray diffraction patterns from various depths in the low sulfur tailings lysimeter 31 5.2 Powder x-ray diffraction patterns from various depths in the main tailings lysimeter 32 5.3 Powder x-ray diffraction patterns from various depths in the total tailings lysimeter 33 5.4 Powder x-ray diffraction patterns at various depths in the low sulfur tailings column 35 5.5 Powder x-ray diffraction patterns at various depths in the main tailings column ' . 36 5.6 Powder x-ray diffraction patterns at various depths in the total tailings column 37 5.7 Mineralogical modal abundance versus depth in the low sulfur tailings lysimeter 40 5.8 Mineralogical modal abundance versus depth in the main tailings lysimeter 41 5.9 Mineralogical modal abundance versus depth in the total tailings lysimeter 42 5.10 Mineralogical modal abundance versus depth in the three columns 43 5.11 Photomicrograph of altered biotite from the total tailings lysimeter 45 5.12 Photomicrograph of altered biotite from the total tailings column 46 5.13 Photomicrograph of partly altered plagioclase from the main tailings lysimeter 49 5.14 Sulfide alteration indices versus depth 48 5.15 Photomicrograph of pyrrhotite from the low sulfur tailings lysimeter altering 49 along the grain's parting 5.16 Photomicrograph of pyrrhotite from the main tailings lysimeter altered along it's parting 51 5.17 Photomicrograph of pyrrhotite from the main tailings lysimeter replaced by native sulfur, 51 iron oxyhydroxide, and covellite 5.18 Photomicrograph of nearly complete pseudomorphic replacement of pyrrhotite 52 5.19 Photomicrograph of pyrrhotite with oxidation rims from the total tailings lysimeter 54 5.20 Photomicrograph of pyrrhotite pseudomorph from the total tailings lysimeter 54 5.21 Photomicrograph of pseudomorph of native sulfur and iron oxyhydroxide 55 in the total tailings lysimeter 5.22 Photomicrograph of leached pyrrhotite from the main tailings oxidation column 56 5.23 Photomicrograph of pyrrhotite pseudomorph and altered pentlandite from the main 56 tailings oxidation column 5.24 Photomicrograph of pyrrhotite pseudomorph from the total tailings oxidation column 58 5.25 Photomicrograph of pentlandite alteration from the main tailings lysimeter 59 5.26 Photomicrograph of oxidation rim on pentlandite from the main tailings lysimeter 59 5.27 Photomicrograph of mottled texture resulting from oxidation of pentlandite 60 5.28 Photomicrograph of oxidation rim around pentlandite from the low sulfur tailings 62 oxidation column 5.29 Photomicrograph of pre-deposition oxidation ofpyrrhotite coexisting with pyrite 62 5.30 Photomicrograph of partly oxidized pyrrhotite coexisting with unaltered chalcopyrite 63 from the main tailings lysimeter 5.31 Photomicrograph of chalcopyrite dissolution and secondary covellite from the total 63 tailings oxidation column 5.32 Photomicrograph of secondary covellite from the total tailings lysimeter 64 5.33 Photomicrograph of a weakly altered slag particle from the main tailings lysimeter 68 5.34 Photomicrograph of altered slag particle and secondary covellite from the total 68 tailings lysimeter 5.35 Photomicrograph of partly altered slag particle from the total tailings lysimeter 69 5.36 Photomicrograph of strongly altered slag particle from the total tailings lysimeter 69 6.1 Powder x-ray diffraction patterns at various depths throughout the pyrrhotite-rich 74 tailings oxidation column 6.2 Mineralogical modal abundance versus depth for the pyrrhotite-rich tailings column 75 6.3 Sulfide alteration index versus depth for the pyrrhotite-rich tailings oxidation column 76 6.4 Photomicrograph of oxidized pyrrhotite and secondary cementing phases from the 78 pyrrhotite-rich tailings oxidation column 6.5 Photomicrograph of weakly altered pyrrhotite and pentlandite from the pyrrhotite-rich 78 oxidation column 7.1 Ca-Mg-Fe ternary diagram for pyroxenes 94 7.2a BSE image and electron probe microanalysis results for altered biotite from the total 105 tailings lysimeter 7.2b Multi-element x-ray maps and BSE image of altered biotite from the total tailings lysimeter 106 7.3a BSE image, photomicrograph, and electron probe microanalysis results of altered biotite 108 from the total tailings oxidation column 7.3b Multi-element x-ray maps and BSE image of altered biotite from the total tailings column 109 7.4 BSE image, photomicrograph, and electron probe microanalysis results of altered biotite 110 from the total tailings oxidation column 7.5a BSE image and electron probe microanalysis results of altered pyrrhotite from the low sulfur 112 tailings lysimeter 7.5b Multi-element x-ray maps and BSE image of altered pyrrhotite from the low sulfur tailings 113 lysimeter 7.6 Multi-element x-ray maps and BSE image of partly altered pyrrhotite from the low sulfur 114 tailings lysimeter 7.7a BSE image and electron probe microanalysis results of altered pentlandite from the low sulfur 115 tailings lysimeter 7.7b Multi-element x-ray maps of altered pentlandite from the low sulfur tailngs lysimeter 116 7.8a BSE image and electron probe microanalysis of an altered pyrrhotite in the main tailings 117 lysimeter 7.8b Multi-element x-ray maps of an altered pyrrhotite in the main tailings lysimeter 118 7.9a BSE image and electron probe microanalysis results of an altered pyrrhotite from the main 120 tailings lysimeter 7.9b Multi-element x-ray maps of an altered pyrrhotite from the main tailings lysimeter 121 7.10a BSE image and electron probe microanalysis results on an altered pyrrhotite in the main 122 tailings lysimeter 7.10b Multi-element x-ray maps and BSE image of altered pyrrhotite in the main tailings lysimeter 123 7.1 la BSE image and electron probe microanalysis of pyrrhotite rimmed by iron oxyhydroxide 124 from the main tailings lysimeter 7.11b Multi-element x-ray maps of pyrrhotite rimmed by iron oxyhydroxide from the main tailings 125 lysimeter 7.12a BSE image and electron probe microanalysis results of altered pentlandite from the mam 126 tailings lysimeter 7.12b Multi-element x-ray maps of altered pentlandite from the main tailings lysimeter 127 7.13a BSE image and electron probe microanalysis results of altered pentlandite from the main 129 tailings lysimeter 7.13b Multi-element x-ray maps of altered pentlandite from the main tailings lysimeter 130 7.14a BSE image and electron probe microanalysis results of altered pentlandite from the main 131 tailings lysimeter 7.14b Multi-element x-ray maps of altered pentlandite from the main tailings lysimeter 132 7.15 BSE image and electron probe microanalysis of altered pentlandite from the main tailings 133 lysimeter 7.16 Multi-element x-ray maps and BSE image of altered chalcopyrite from the main tailings 134 lysimeter 7.17a BSE image and electron probe microanalysis results of partly altered pyrrhotite and 136 pentlandite from the main tailings lysimeter 7.17b Multi-element x-ray maps of partly altered pyrrhotite and pentlandite from the main tailings 137 lysimeter 7.18a BSE image and electron probe microanalysis results of a multi-mineralic association from 138 main tailings lysimeter 7.18b Multi-element x-ray maps and BSE image of a multi-mineralic association from the main 139 tailings lysimeter 7.19a BSE image and electron probe microanalysis results of altered pyrrhotite coexisting with 140 chlorite, biotite, ilmenite, and quartz from the main tailings lysimeter 7.19b Multi-element x-ray maps of altered pyrrhotite coexisting with chlorite, biotite, ilmenite, and 141 quartz from the main tailings lysimeter 7.20a BSE image and electron probe microanalysis results of altered pyrrhotite from the total 143 tailings lysimeter 7.20b Multi-element x-ray maps and BSE image of altered pyrrhotite from the total tailings 144 lysimeter 7.21a BSE image and electron probe micoanalysis results of pyrrhotite pseudomorph from the 145 total tailings lysimeter 7.21b Multi-element x-ray maps and BSE image of pyrrhotite pseudomorph from the total 146 tailings lysimeter 7.22a BSE image and electron probe micoanalysis results of pyrrhotite pseudomorph from the 147 total tailings lysimeter 7.22b Multi-element x-ray maps and BSE image of pyrrhotite pseudomorph from the total 148 tailings lysimeter 7.23a BSE image and electron probe micoanalysis results of pyrrhotite pseudomorph from the 150 total tailings lysimeter 7.23b Multi-element x-ray maps and BSE image of pyrrhotite pseudomorph from the total 151 tailings lysimeter 7.24a BSE image and electron probe micoanalysis results of pyrrhotite pseudomorphs from the 152 total tailings lysimeter 7.24b Multi-element x-ray maps and BSE image of pyrrhotite pseudomorphs from the total 153 tailings lysimeter 7.25a BSE image and electron probe microanalysis results of altered pyrrhotite from the low 154 sulfur tailings oxidation column 7.25b Multi-element x-ray maps and BSE image of altered pyrrhotite from the low sulfur tailings 155 oxidation column 7.26a BSE image and electron probe microanalysis results of altered pyrrhotite from the low 157 sulfur tailings oxidation column 7.26b Multi-element x-ray maps of altered pyrrhotite from the low sulfur tailings 158 oxidation column 7.27a BSE image and electron probe microanalysis results of altered pyrrhotite from the low 159 sulfur tailings oxidation column X I 7.27b Multi-element x-ray maps and BSE image of altered pyrrhotite from the low sulfur tailings 160 oxidation column 7.28a BSE image and electron probe microanalysis results of altered pyrrhotite and pentlandite 161 from the low sulfur tailings oxidation column 7.28b Multi-element x-ray maps and BSE image of altered pyrrhotite and pentlandite from the 162 low sulfur tailings oxidation column 7.29a BSE image and electron probe microanalysis results of pyrrhotite pseudomorphs and 164 altered pentlandite from the main tailings oxidation column 7.29b Multi-element x-ray maps and BSE image of pyrrhotite pseudomorphs and altered 165 pentlandite from the main tailings oxidation column 7.30a BSE image and electron probe microanalysis results of pyrrhotite pseudomorph 166 from the main tailings oxidation column 7.30b Multi-element x-ray maps of pyrrhotite pseudomorph from the main tailings 167 oxidation column 7.3 la BSE image and electron probe microanalysis results of a partly altered slag particle from 169 the total tailings lysimeter 7.31b Multi-element x-ray maps and BSE image of partly altered slag particle from the total 170 tailings lysimeter 7.32 Multi-element x-ray maps and BSE image of partly altered slag particle from the total 171 tailings lysimeter 7.33a BSE image and electronprobe microanalysis results of a partly altered slag particle from 172 the total tailings lysimeter 7.33b Multi-element x-ray maps and BSE image of partly altered slag particle from the total 173 tailings lysimeter 7.34a BSE image and electronprobe microanalysis results of a partly altered slag particle from 174 the total tailings lysimeter 7.34b Multi-element x-ray maps and BSE image of partly altered slag particle from the total 175 tailings lysimeter 7.35 BSE image and electronprobe microanalysis results of a partly altered slag particle from 176 the total tailings lysimeter 7.36 BSE image and electronprobe microanalysis results of a partly altered slag particle from 178 the total tailings lysimeter ACKNOWLEDGMENTS xii It wasn't until I attempted my Master's degree that I realized the importance of the acknowledgment page, having said that, I would like to thank the many people who deserve thanks and recognition for the help they gave me, I couldn't have done it without them. I would like to start by thanking Inco, Ltd. for providing and funding this project, and in particular Rod Stuparyk at Inco for his constant enthusiasm and help. I would also like to thank Dr. David Blowes and Christine Hanton-Fong at the Waterloo Centre for Groundwater Research for their collaboration and help with my thesis. Partial funding for this project was also provided by the Natural Sciences and Engineering Research Council of Canada (NSERC). I would like to thank my advisor Dr. Lee Groat for his help and for taking me on as a graduate student in the first place, a brave deed. Dr. Mati Raudsepp deserves my gratitude for his technical, academic, and all-around support. I owe tremendous thanks to Dr. John Jambor, for his never-ending patience and equally as grand depth of knowledge, I am constantly amazed by him. Thanks are also due to Dr. Rick Lawrence and Dr. Roger Beckie for their help as members of my committee. My mentor and friend, Dr. Heather Jamieson deserves thanks for showing me how interesting mine waste can be, and believing in me. I thank my family for their unconditional support, and lastly, I have to thank, my friends, my support group, my peers; especially Julie Mcintosh, Anita Lam, and David Awram. You guys are great. Thank you. 1 1.0 ACIDIC DRAINAGE FROM MINE WASTE Acid rock drainage (ARD), a term that has been used increasingly over the past quarter century, has become a problem for the mining industry as awareness and understanding of the consequences increase. A R D has typically been defined as seepage, with a pH less than 5, originating from a tailings pile, a waste rock pile, or exposed sulfide-rich rock. It is not necessarily the acidity that is the direct problem, which instead may be the deleterious effects that arise from dissolved components that have been solubilized by acidic reactions. A R D is typically enriched in soluble Fe, Mn, Ca, Mg, A l , S0 4 , and at times, in heavy metals such as Pb, Cu, Zn, Ni, Co, As and Cd. Acidic waters alone can cause discolouration and turbidity in receiving waters, but it is mainly the loading of ions mobilized by the acid that causes a reduction in aquatic flora and fauna, bioaccumulation of metals, and the reduction in the quality of groundwater. Acidic seepage has in the past been a problem associated with mine closure, but has more recently become linked with the planning and development of prospective mines. Closure costs previously dealt only with waste disposal, and there generally was minimal concern for rehabilitation or potentially hazardous seepage originating from the waste. In the last 25 years, abandonment without rehabilitation of mine sites has become prohibited without rehabilitation, greatly adding to the costs and liabilities of mining companies. Thus, there has been a significant increase in A R D research, specifically in the generation, consequences and prevention of ARD. 1.1 Acid Generation The primary cause of acid generation is the oxidation of sulfide minerals, predominantly pyrite and pyrrhotite. Many factors contribute to sulfide oxidation, including: pH of solutions in contact with the 2 sulfide minerals; the origin, chemistry, surface area and morphology of the minerals; oxygen concentration, and ferric iron concentration in solution; temperature; galvanic interactions with coexisting minerals; and bacterial interactions. The oxidation rate can vary for different minerals, and for individual minerals, because of variations in their thermodynamic properties, the kinetics of the system, and the presence or absense of precipitated secondary minerals. The secondary minerals created as a result of sulfide oxidation often occur as rims. These rims may act as solid-phase reaction zones retarding sulfide oxidation (Ahonen and Tuovinen, 1994). There has been considerable work done investigating the phenomenon of sulfide oxidation, including more recent studies on the oxidation mechanisms of pyrite (Evangelou and Zhang, 1995), and the rate of pyrite oxidation ( Bierens de Harm, 1991; Moses et al., 1987), as well as studies investigating surface reactions occurrring on leached pyrrhotite (Pratt et al., 1994), the kinetics of pyrrhotite oxidation (Nicholson and Scharer, 1994), and the iron transformation of pyrrhotite subjected to bioleaching experiments (Ahonen and Tuovinen, 1994). Pyrite and pyrrhotite are the two major potentially acid generating minerals in most mine waste environments. 1.1.1 Pyrite oxidation The chemical reaction that governs the oxidation of pyrite by oxygen is given by: This produces ferrous ion in solution which, in the presence of oxygen, can be further oxidized to ferric iron: Ferric iron in solution may then precipitate, possibly as an iron hydroxide phase as seen in reaction (3): FeS2 + 7 / 2 0 2 + H 2 0 <-> Fe 2 + + 2S04 2" + 2¥t (1) Fe 2 + + V4O2 + r f o Fe 3 + + 1/2H20 (2) Fe 3 + + 3H 2 0 <r> Fe(OH) 3 ( S ) + 3rT (3) 3 or the ferric ion itself may oxidize pyrite: FeS2(S) + 14Fe3+ + 8H 2 0 <-> 15Fe2+ + 2S04 2" + 16rf (4) At pH conditions below 4.5, and perhaps as high as 9 (Moses et al., 1987), the oxidation of pyrite, and the oxidation of ferrous to ferric iron, are both more rapid by reaction with ferric iron than by oxygen. The effectiveness of ferric iron as an oxidant is thought to be due to two reasons discussed below. Ferric iron has a high chemical binding power that allows physical attachment to the pyrite surface, a process that oxygen cannot do. The attachment is attributed to physical adsorption and can be explained using molecular orbital theory. Ferric iron has a vacant orbital so, in order to transfer electrons, it binds to the surface by forming a persulfido bridge (Fe-S-S-Fe(H20)5(OH)2+). Electrons are transferred from the highest occupied molecular orbital (S 2 2) to the lowest (Fe3+). Oxygen does not form a direct physical bridge with pyrite, thus resulting in a slower reaction rate (Moses et al., 1987). Bacteria, which are ubiquitous in mine waste environments, may indirectly increase the oxidation rate of sulfides by increasing the concentration of ferric iron via the oxidation of ferrous iron, therefore contributing to the effectiveness of oxidation by ferric iron. The oxidation rate of bacterially catalyzed sulfide oxidation reactions may be as much as six orders of magnitude greater than sulfide oxidation rates in a bacteria-free environment (Evangelou and Zhang, 1995). The bacterial catalysis has been suggested to Occur via a succession of bacterial species. Neutrophilic bacteria such as Thiobacillus thioparus are believed to be present at neutral pH conditions. In slightly more acidic conditions, pH 4.5 to 3.5, the acid- tolerant, iron oxidizing, metallogenium bacteria thrive (Walsh and Mitchell, 1972). As oxidation continues and pH drops even further, acidophilic species begin to dominate. The acidophilic, chemolithotrophic bacteria help maintain low pH conditions favourable to their survival and to oxidative dissolution of sulfide minerals by ferrous iron oxidation. Thiobacillus ferrooxidans is an example of a bacteria species, indigenous in mine waste, which is able to oxidize iron, sulfur, metal sulfides, and other reduced inorganic 4 sulfur compounds. The Leptospirillum ferrooxidans are an iron oxidizing species unable to oxidize sulfur, and Thiobacillus thiooxidans and Thiobacillus cuprinus are sulfur oxidizing bacteria, but are incapable of oxidizing iron (Bhatti etal., 1994). 1.1.2 Pyrrhotite oxidation Pyrrhotite, which is the mineral of principal concern in the Inco Ltd. Copper Cliff tailings area, oxidizes at rates 20 to 100 times faster than pyrite (Nicholson and Scharer, 1994). The general formula of pyrrhotite is Fei..vS, where x can vary from 0.125 (Fe7Ss) to 0.0 (FeS). The crystal structure of pyrrhotite varies with the iron deficiency; the Fe7Ss variety is monoclinic (and magnetic), those with intermediate stoichiometrics, FegSio to FenSi 2, are hexagonal or orthorhombic (nonmagnetic), and equimolar pyrrhotite, known as troilite, is hexagonal (and nonmagnetic) (Nicholson and Scharer, 1994). The iron deficiency is believed to be the main reason for the high reactivity of pyrrhotite. The overall reaction in which oxygen is the primary oxidant is given by: Fe,. xS ( s ) + (2-72)02 +, xH 20 o (l-x)Fe2+ + S042" + 2xH+ (5) Oxidation of the dissolved Fe 2 + in equation (5) results in the precipitation of ferric hydroxide and the creation of acid: Fe 2 + + V4O2 + 5 / 2 H 2 0 o Fe(OH)3(S) + 2FT (6) If the oxidation reactions do not go to completion, elemental sulfur can be produced via the reaction: Fe,.,S ( s ) + ((1-v)/2)02 + 2(l-x)Fr o (l-x)Fe2+ + S° + (l-x)H20 (7) or 4Fe0.,)S(S) + (3-3x)02 + (12-12x)rT o (4-4x)Fe3+ + 4S° + (6-6x)H20 (8) Ferric iron can also act as an oxidant. If the reaction goes to completion, sulfate ions can be produced as in equation (9). If the reaction does not go to completion, elemental sulfur may again be produced as an intermediate (10): 5 Fe,, vS ( S ) + (8-2x)Fe3+ + 4H 2 0 o (9-3x)Fe2+ + S 0 4 2 + 8FT (9) F e ^ S ( s ) + (2-2x)Fe3+ (3-3x) Fe 2 + + S 0 ( S ) (10) Another common initial phase observed in the oxidative reaction of pyrrhotite is marcasite, FeS2, whose formation can be illustrated by the reaction: 2Fe,.,.S(S) + (72-x)02 + (2-4x)rT ±> FeS 2 ( S ) + (l-2x)Fe2+ + (l-2x)H20 (11) The early-developed phases, native sulfur and marcasite, are metastable in the presence of oxygen and will eventually oxidize. The evolution of H 2 S ( g ) has been detected in some laboratory' oxidation studies of pyrrhotite (Ahonen and Tuovinen, 1994), suggesting non-oxidative breakdown of pyrrhotite as given by: Fe(1..v)S(S) + 2fT <•» (1 -3x)Fe2+ + 2xFe3+ + H 2 S (12) This anaerobic reaction liberates ferric iron which may act as an oxidant, and produces acid. 1.2 Acid Neutralization Some minerals present in mine tailings are capable of acid neutralization and therefore provide a buffering capacity to the system. To be a significant buffer, a neutralizing mineral must react at a rate comparable to the rate of sulfide oxidation. The only minerals capable of this are carbonate minerals, for example, calcite (CaC0 3). The dissolution of calcite in the presence of C 0 2 ( g ) is given in equation (13): C a C 0 3 + C 0 2 ( g ) + H 2 0 o C a 2 + + 2HC0 3 - (13) This reaction may occur in the unsaturated zone, where atmospheric C 0 2 ( g ) can penetrate into the tailings or waste rock; however, below the water table, C 0 2 ( g ) concentrations are negligible, and calcite dissolution occurs via the reaction: C a C 0 3 + FT o C a 2 + + H C 0 3 " (14) Dolomite, another carbonate mineral, can also dissolve at similar rates to those for sulfide oxidation and provide some neutralization potential: CaMg(C0 3) 2 + 2H 2 S0 4 <H» CaS0 4 + M g S 0 4 + 2H 2 0 + 2C0 2 ( g ) (15) In the long term, silicate minerals with slower reaction kinetics may begin to dissolve and add to the neutralizing capacity of the tailings or waste rock site. The relevant silicate mineral dissolution reactions given below are taken from Ritchie (1994). Anorthite dissolution: CaAl 2 Si 2 0 8 + 2rf + 6H 2 0 <H> C a 2 + + 2A13+ + 2H 4 Si0 4 + 60H (16) or CaAl 2 Si 2 0 8 + 2Ff + H 2 0 ±+ C a 2 + + Al 2 Si 2 0 5 (OH) 4 (17) Albite dissolution: NaAlSi308(s) + FT + 9 / 2 H 2 0 Na + + 2H4Si04 + '/jAbSizOjtOH)^) (18) K-feldspar dissolution: K A l S i 3 0 8 ( S ) + FT + 9 / 2 H 2 0 <-> K + + 2H4Si04+ 1 / 2 Al 2 Si 2 0 5 (OH) 4 ( S ) (19) Muscovite dissolution: KAl 2[AlSi3O 1 0](OH) 2 (s) + r f + 3 / 2 H 2 0 o K + + ^AUSbOstOH)^) (20) Biotite dissolution: KMg, 5Fe, 5AlSi 3 0,o(OH) 2 ( S ) + 7FT + V2H20 o K + + 3 / 2 M g 2 + + 3 / 2 Fe 2 + + 214,8104 + V2Al2Si205(0H)4(s) (21) The proton (FT) is an integral reactant in the reactions given above; consequently, these reactions are all pH dependent. As the pH changes, the dissolution of neutralizing minerals results in a temporary' buffering of the system. A step-like pattern can be seen as the solubilities of these minerals are met and surpassed (Blowes et al., 1995a; Morin and Cherry, 1986). 1.3 Metal Loading Metal loading in effluents originating from, or in contact with, acid-producing sites is the primary environmental concern for most mine sites. The migration of metals is dependent on physical controls such as climatic conditions, waste permeability, the availability and pressure of pore H 2 0 , and mechanisms of transport such as stream flow or diffusion. Among the many chemical factors that may influence metal loading are pH, Eh, adsorption, and the type and concentration of each metal that is mobilized. Biological controls can also be significant, including the role of iron and sulfur oxidizing bacteria in the enhancement of metal leaching, and bacterial capacity for adsorption and precipitation of metals in solution. 1.4 Preventative Techniques Numerous preventative techniques are currently undergoing research or being employed by the mining industry in an effort to deal with ARD. The more common of these techniques are briefly discussed below. 1.4.1 Underwater disposal The disposal of mine waste underwater is one of the more common oxygen inhibiting techniques (Nolan, Davis & Associates, 1987; Robertson, 1987). Oxygen has a very low solubility and diffusion rate in water, and these may consequently slow sulfide oxidation. Secondary phases that may have formed from the oxidation of sulfide minerals prior to disposal underwater, may pose a danger in that their dissolution can release oxidants such as oxygen and ferric iron and metals stored in the secondary phases. In addition, it may be difficult to maintain a water cover indefinitely, because the cover would depend on long-term local hydrologic and climatic conditions. 8 1.4.2 Wetland treatment system Wetland treatment requires either the creation of a wetland on an existing waste pile, or burial of waste under a wetland in order to provide a water cover and a reducing environment (Nolan, Davis & Associates, 1987). As with underwater disposal, wetland maintenance may be difficult and site specific. An added disadvantage is that the roots of some aquatic plants such as cattails release oxygen that acts as an oxidant of the sulfides present in the waste. Wetlands may also be impractical for elevated waste dumps and side slopes. 1.4.3 Neutralization by alkaline materials Ideally, mine waste would contain alkaline minerals in significant abundance to neutralize the acid produced by the waste; however, this is rarely the case. Another method of dealing with acid generation is to add the alkaline materials needed to buffer the acidity (Morin and Cherry, 1986; Blowes et al., 1991). Limestone or sodium hydroxide are the two most commonly added materials used as pH buffers, and to hydrolyze most heavy metals which, at a pH around 9, precipitate as metal hydroxides. However, this method is not as effective as once believed, because limestone has a limited solubility and exhibits the tendency to be armored by ferric hydroxide precipitates. In addition, some waste material requires tremendous amounts of neutralizer, which can pose a volumetric (and therefore cost) problem. The success of this technique is greatly dependent on the movement of water through the system, the proportion of excess neutral material and the type and purity of the neutralizing additive (Steffen, Robertson and Kirsten (B.C.) Inc., 1989). 1.4.4 Inhibition of iron-oxidizing bacteria The addition of anionic surfactants (common cleaning detergents), organic acids, food preservatives and bactericides (Stichbury et al., 1995) to mine waste to control bacterial growth is another, less favorable technique (Watzlaf, 1986). These compounds cause hydrogen ions to move through and deteriorate bacterial membranes. The primary problem with this method is that the surfactants are highly soluble, so repeated treatments are required. The cost of this technique may be several thousands of dollars per hectare of surface, and does not imply that acid generation will cease. 1.4.5 Microencapsulation techniques Coating the sulfide grains to prevent oxidation has also been examined (Hester & Associates, 1984). In this method, phosphates are added to the system and react with ferric iron to form the mineral strengite (FeP042H20), which preferentially coats the sulfide surfaces. This method has been applied only to pyrite-rich mine waste and has not yet been proven to work for pyrrhotite-rich waste. It would be difficult to guarantee the complete encapsulation of all grains and may call for massive disturbance of the previously deposited waste materials during application. 1.4.6 Capping techniques Capping techniques using various materials have also been tested (Nolan, Davis and Associates, 1987; Ritchie and Harries, 1987). These materials include soil covers, geotextiles, polymeric materials, wood-chip and manure mixtures, and sulfur-poor tailings. Factors that must be considered when examining a capping material are climatic stability, inertness and longevity of the material, and economic 10 viability. The effectiveness of the cover is dependent on the cover's resistance to factors such as cracking, the burrowing effects of roots and animals, and erosion and degradation due to weathering and frost action. 2.0 INCO'S COPPER CLIFF TAILINGS: DESCRIPTION AND CLOSURE PLAN 11 The description of the Copper Cliff tailings area and closure options for the tailings being considered by Inco Ltd. are presented here as taken from Puro et al. (1995). 2.1 Copper Cliff Tailings Basin The Copper Cliff tailings area is approximately 400 km north of Toronto, Ontario, just outside the town of Copper Cliff in the world-famous Sudbury district (see appendix A for an account of the geological history and mining activity in the Sudbury area). More than 10% of all tailings in Canada are located at the Inco Ltd.'s Copper Cliff tailings area, which makes it one of the largest reservoirs for potentially acid generating tailings in North America. Deposition of the tailings began in the 1930s, and the tailings now cover more than 2,225 hectares of land. Upon closure, projected for the year 2025, the estimated amount of tailings will exceed 725 million tonnes. The Copper Cliff tailings area is bounded by bedrock that follows the topography of the Canadian Shield. During the early development stages of the tailings basin, several starter dams were constructed using local till material in order to locally contain the tailings. As deposition continued, the dams were raised by spigotting and upstream constaiction with coarse tailings. The dams were designed to seep to maintain structural stability by sustaining a low phreatic head. There are two primary areas in the tailings basin (figure 2.1). The first and older area of deposition is the old stack which operated from 1936 to the late 1980's, and is made up of the areas labeled A, CD, M , P, Q, and Po, the last a storage area for pyrrhotite concentrates. All of these areas, except the pyrrhotite storage area, are now covered with vegetation (predominantly grasses and legumes) and ponds. 12 The second area is named the R-area where the tailings, other than 20% used for backfill or sandfill, produced since 1986 have been deposited. The internal starter dams in this area were constructed using rock, and no cover has yet been established. Figure 2.1: Map of the Copper Cliff tailings area. After Puro et al. (1995). In the past, the area received tailings from four mills: Copper Cliff, Creighton, Frood Stobie, and Clarabelle. Also deposited were pyrrhotite tailings and iron oxide products (magnetite and hematite) from the Iron Ore Recovery Plant. The Creighton mill and the Iron Ore Recovery Plant are now closed, and circuit modifications in the remaining mills have been done to put a Pyrrhotite Rejection circuit on line. The majority of the tailings comes from the Frood Stobie, Clarabelle, and Copper Cliff milling circuits. There are three tailings streams originating from these circuits, a main rock tailings (1.0 wt.% S), a pyrrhotite concentrate (30 wt.% S) and a pyrrhotite reject tailings (10 wt.% S). At the Clarabelle mill, the 13 main rock tailings are mixed with the pyrrhotite reject tailings to produce a product referred to as the total tailings (2.5 wt.% S). In 1991, the milling operations were consolidated to the Clarabelle mill, which has a capacity of 36,000 tonnes/day and receives -20 cm ore from 10 operating mines in the Sudbury Basin. The ore grades sent to the mill are typically 1.2% Ni and 1.1% Cu, two of the metals of primary concern with respect to water quality in the Copper Cliff tailings. The role of both of these metals in the environment is given in appendix B. The milling process at Clarabelle begins with crushing, using both rod and ball techniques, semi- autogeneous grinding, magnetic separation, froth flotation and regrinding. The concentrates are dewatered and dried before being smelted at one of the two Inco Ltd. oxygen flash furnaces at the Copper Cliff Smelter (Vuro etal., 1995). Numerous minerals have been found in the Sudbury rocks and have been described in detail by Hawley (1962) and references therein. They are summarized in table 2.1. M I N E R A L T Y P E M I N E R A L F O R M U L A Native Metals and Semimetals Gold (Electrum) Au Silver Ag Bismuth Bi Tellurides, Tetradymite Bi 2Te 3S Sulfides, Hessite Ag 2Te Arsenides, Chalcocite (?) Cu 2S Bismuthides Maucherite Ni , iAs s Heazlewoodite Ni 3 S 2 Bornite Cu 5FeS 4 Galena PbS Sphalerite ZnS Chalcopyrite CuFeS2 Stannite Cu 2FeSnS 4 Pyrrhotite Fe,.xS Valleriite Cu 2Fe 4S7 Nickeline NiAs M I N E R A L T Y P E M I N E R A L F O R M U L A Millerite NiS Pentlandite (Ni,Fe)9S8 Cubanite CuFe2S3 Violarite Ni 2 FeS 4 Bismuthinite (?) Bi 2 S 3 Pyrite FeS2 Pyrite (nickeloan) (Fe,Ni)S2 Molybdenite MoS 2 Sperrylite PtAs2 Michenerite PdBi 2 Froodite PdBi 2 Gersdorffite NiAsS Marcasite FeS2 Marcasite (nickeliferrous) (Fe,Ni)S2 Cobaltoan arsenopyrite (?) (Fe,Co)AsS Parkerite Ni 3 Bi 2 S 2 Skutterudite (Co,Ni)As3.x Sulphosalts Tetrahedrite (?) (Cu,Fe) 1 2Sb 4Si 3 Matildite AgBiS 2 Oxides Magnetite Fe 3 0 4 Ilmenite FeTi0 3 Hematite Fe 2 0 3 Cassiterite (?) Sn0 2 Hydrous Oxides, Goethite Fe 2 0 3 nH 2 0 Sulfates, Chalcanthite C u S 0 4 5 H 2 0 Arsenates Melanterite FeS0 4 7H 2 0 Morenosite N i S 0 4 7 H 2 0 Annabergite Ni 3 (As0 4 ) 2 8H 2 0 Erythrite Co 3 (As0 4 ) 2 8H 2 0 Halides Fluorite CaF 2 Carbonates Calcite C a C 0 3 Dolomite CaMg(C0 3 ) 2 Siderite FeC0 3 Silicates Quartz Si0 2 Feldspars Albite NaAlSi 3 0 8 Labradorite (Na,Ca)(Al,Si)408 Pyroxene Enstatite (Mg,Fe)Si 20 6 Amphiboles Actinolite Hornblende Hastingsite Micas Sericite Biotite Chlorite Clinochlore and pennantite Garnet Almandine Zircon Titanite Prehnite Table 2.1: Minerals reported in the Sudbury Igneous Complex. After Hawley (1962). 15 2.2 Closure Options In 1993, SENES Consultants Ltd. developed a series of closure alternatives for the Copper Cliff tailings area. Four options were suggested on the basis of environmental effectiveness for the abatement of acidic, metal-rich seepage and the overall cost benefit. These options are described below. 2.2.1 Option 1 Option 1 deals with the development of the currently utilized R area. The treatment strategy for this option is based on the following points: all dams except the southern R-4 dams are constructed as pervious dams using spigotted tailings and upstream construction with total tailings (2.5 wt. % S); future pyrrhotite will be deposited below the final water table after R- l is filled; tailings will be vegetated at closure; water management will involve spillways from R-4 into the Q area, the P area into Copper Cliff Creek, and the M and CD areas into A area; seepage and runoff collection will continue, with diversion of all waste waters to the Copper Cliff Waste Water Treatment Plant, which would operate for several hundred years amnd would deposit sludge into existing basins. 2.2.2 Option 2 The second option is a modification of the first. In this scenario, acidic drainage is prevented by addition of a shallow water. The final pond elevation is to be raised in the R-4 area to submerge the tailings under a shallow water cover, and pyrrhotite in the R- l area is to be buried below a cap of total 16 tailings (2.5 wt. % S). The cover is to be added to reduce the area of exposed tailings and therefore reduce the sulfur available for oxidation. This option differs from option 1 by: raising the 1800 m long water retaining internal dam between R-4 and Q areas; raising the R-l area with a total tailings cap to place all existing pyrrhotite below the water table. 2.2.3 Option 3 This option has essentially the same features as option 2 with the exception of the cap used in the R- l area. This option suggests using the main rock tailings (1.0 wt. % S) for the cap and for dam construction in the R-area. This will further reduce the acid generating potential of the tailings. The following changes would be needed: R-area dam development would proceed with main rock tailings; raising of the R-1 area with main tailings cap to place all existing pyrrhotite below the water table and reduce the acidity from this area. 2.2.4 Option 4 The fourth option is yet another derivation of the second option in which the low sulfur tailings (0.4 wt. % S) would be used for dam construction and capping material. The following changes would need to be made: the flotation circuit at the Clarabelle mill would have to be modified to produce low sulfur tailings; raising of the R-l area with low sulfur tailings cap to place all existing pyrrhotite below the water table and substantially reduce the acidity from the R area. 17 All four options would require perpetual treatment of seepage from both the old stack and the R area. A comparison of these options in terms of overall environmental benefit shows that the use of low sulfur tailings is the superior option because of the focus on the prevention rather than long term treatment of ARD. The initial costs for expansion of the Clarabelle mill's flotation capacity would be offset by a reduction in the demand for lime used for ARD neutralization. Research is currently being done, in part by this study, by Inco Ltd., and the Waterloo Centre for Groundwater Research, to confirm that the low sulfur tailings (0.4 wt. % S) are suitable to use as a capping material. 3.0 LOW SULFUR TAILINGS: PRODUCTION AND INITIAL TESTING 18 The following description of the low sulfur tailings production and the experimental work done towards decommissioning, prior to the fall of 1995, was primarily taken from Stuparyk et al. (1995) and Blowes etal. (1995b). 3.1 Production of Low Sulfur Tailings The low sulfur tailings (0.4 wt. % S) were produced at the Clarabelle mill as part of a plant test in 1993. Approximately 900 tonnes/day of main tailings (1.0 wt. % S) were processed in a line of 2.8 m3 Denver flotation cells. The low sulfur tailings were produced at a pH of 6-7, with a small xanthate dosage, and 15 minutes nominal retention time. By expanding the main circuit flotation capacity at the Clarabelle mill by 25% and installing a facility for storing and adding acid, approximately 23,400 tonnes/day of low sulfur tailings could be produced. The mill would also produce 900 tonnes/day of sulfide concentrate that would be deposited under a water cover in the R-l area. 3.2 Laboratory-based Tests Initial testing of the low sulfur tailings was done in Inco Ltd.'s J. Roy Gordon Research laboratory. Tests were carried out on three tailings types for comparison: the low sulfur tailings (0.4 wt. % S), the main tailings (1.0 wt. % S), and a total tailings (2.5 wt. % S). 3.2.1 Acid Base Accounting tests- Acid Base Accounting tests of the three tailings types were done to measure the maximum acid generation potential (AP) and the maximum neutralizing potential (NP) of the tailings to calculate the net neutralization potential (NNP=NP-AP). Predictions were made on the basis of British Columbia Acid Mine Drainage Task Force guidelines. Tailings with sulfide minerals whose NNP (in kg CaCC>3 eq/tonne material) is greater than 20 are considered nonacid generating, an NNP between 20 and -20 puts the tailings in an uncertain category, and tailings with an NNP less than -20 are considered acid generating (Steffen, Robertson and Kirsten (B.C.) Ltd., 1989). Inco Ltd. used the modified Sobek method of Acid Base Accounting whereby the AP was calculated on the basis of total sulfur analysis, and the NP was determined by an excess HCI treatment, FLO, addition for removal of siderite, and titration of unreacted acid with NaOH. The results of these tests, as seen in figure 3.1, have shown that the total tailings (2.5 wt. % S) fall into the acid generating category. The main tailings (1.0 wt. % S) lie on the border between the acid generating category and the region of uncertainty. The low sulfur tailings (0.4 wt. % S), though resulting in a positive NNP value, also fall into the region of uncertainty. All three tailings types had similar NP values, which suggests that the results are a reflection of the varying sulfide concentrations rather than a variation in the potentially neutralizing mineral content. Inco's Copper Cliff tailings are low in carbonate minerals, but contain many silicates and aluminosilicates that can provide some acid consumption ability. 2() 3 CO 2.5 2 1.5 1 0.5 \ • \ POTENTIALLY ACID GENERATING ZONE OF UNCERTAINTY * X -60 -40 -20 20 NON-ACID GENERATING • Total Tailings O Main Tailings x Low Sulfur Tailings 40 60 Net Neutralization Potential (kg C a C O , eq./tonne) Figure 3.1: Net neutralization potential versus weight percent sulfur for the three tailings types. After Stuparyk et al. (1995). 3.2.2 Column oxidation experiments Column oxidation experiments were set up at Incos Central Process Technology Laboratory in June 1993 to help predict the drainage quality of the three types of tailings A schematic representation of the oxidation columns is illustrated in figure 3.2. The columns, designed to hold approximately 25 kg of unsaturated tailings, were constructed from PVC pipe approximately 15.3 cm in diameter, and were set up in triplicate for each of the tailings types, two in opaque pipe, and one in clear pipe The tailings were placed on top of a 20 cm thick layer of crushed quartz which initially acted to hold the tailings in the columns. The columns are open at the top and are sealed at the bottom in order to mimic atmospheric conditions in the tailings basin. The tailings arc irrigated with de-ionized water at a rate of 550 mL/week, or equivalent to precipitation of 25 mm/week (2.5 times more than the annual rainfall in the Sudbury region). This volume is equivalent to the annual rainfall accelerated to occur in a 20 week period. The seepage from each column was collected in a sealed, anoxic collection flask. A U-tube attached to the base 21 of the column provides the pathway for the seepage to the collection flask and prevents oxygenation at the base of the column. The system is kept at atmospheric pressure by purging the collection flask with nitrogen, while an air trap maintains anoxic conditions in the collection flask. The pH, redox potential, specific conductance, total alkalinity, acidity, SO42' concentration and major metal concentrations are analyzed weekly, and chemical characterization of the solid samples was done for each of the tailings types. 65 cm 20 cm PVC column Tailings N 2 101.3 Kpa 1 t Quartz sand Figure 3.2: Schematic representation of the laboratory oxidation column experiments. After Stuparyk et al. (1995). The initial differences in bulk chemistry between the three tailings types can be seen in table 3.1. The main variations between the three tailings types are the concentrations of Cu, Fe, Ni and S, and this can be accounted for by the differences in sulfide abundance. 23 cn E. c o n s c ts o c o o Cumulative rainfall (mm) 05 E o o CD O CD E c o c 0> O C O o "3 c n o Cumulative rainfall (mm) Cumulative rainfall (mm) 10.00 100 0.1 0.01 - + - I H H 1- 0 200 400 600 800 1000 1200 1400 Cumulative rainfall (mm) | Total Tailings Q Main Tailings | Low Sulfur Tailings Figure 3.3: Cumulative rainfall versus pH. sulfate concentration, iron concentration and nickel concentration in the laboratory oxidation columns for each of the three tailings tvpes. After Stuparvk et al. (1995). 22 Element low sulfur tailings main tailings total tailings (%) (0.4 wt. % S) (1.0 wt. %S) (2.5 wt. % S) Al 6.97 6.83 6.8 C 0.1 0.11 0.1 Ca 4.46 4.77 4.48 Co 0.006 0.006 0.007 C r 0.042 0.039 0.035 Cu 0.072 0.094 0.109 Fe 8.64 9.51 10.3 K 0.94 0.82 0.87 M g 3.04 3.42 3.04 M n 0.128 0.126 0.121 Ni 0.083 0.108 0.159 S 0.51 1.32 1.93 Si 26.2 25.3 25.4 Table 3.1: Bulk chemical analysis of low sulfur tailings, main tailings and total tailings prior to deposition in the field lysimeters and oxidation columns. After Stuparyk et al. (1995). After the addition of 1400 mm of cumulative rainfall, or the equivalent of 2.8 years (3 oxidation seasons), the main differences between the three varieties of tailings are seen in the concentrations of Ni, Fe and S O / " in the outflow solutions. For the first 300 to 400 mm of cumulative rainfall, dissolved Ni, Fe and SO42" concentrations were approximately equal in each of the three tailings types. With additional rainfall, the total tailings began to produce acidic drainage and higher concentrations of Ni, Fe and S0 4 2" in the effluent, the main tailings exhibited slight increases in Ni, Fe and S0 4 2", but the low sulfur tailings showed no significant increase. After approximately 900 mm of rainfall, seepage from the total tailings became even more acidic and contained higher levels of dissolved constituents. When the equivalent of 1300 mm of cumulative rainfall had been added, the main tailings began to deviate significantly from the low sulfur tailings with respect to pH and dissolved Ni, Fe and S0 4 2". The results are given graphically in figure 3.3. 24 3.3 Field-based Tests 3.3.1 Field lysimeter test pits In conjunction with the laboratory oxidation tests, field lysimeter test pits for each of the three tailings types were built in June 1993. Each of the three field lysimeters, constructed to hold approximately 180 tonnes of tailings, i s l 0 m x l 5 m x 2 m and has a 1.1 mm thick polyethylene liner that isolates the tailings from the surrounding groundwater. A drain beneath each lysimeter is used to tap the downflow originating from precipitation and snowmelt. The drains are composed of 10 cm ABS piping that is overlain by a quartz drainage layer, 30 cm thick, which is covered by a 2 cm thick geotextile membrane. A monitoring program was set up by the Waterloo Centre for Groundwater Research to measure the pore-gas, pore-water and solid-phase compositions versus depth on a semi-annual basis. The pore-gas composition (02 and C02) was determined using a NOVA model 305LBD portable gas analyzer. Water samples from the vadose zone were collected using a modification of an immiscible-displacement technique which isolated the sample from atmospheric 02. The moisture content of the tailings was determined using a neutron probe (CPN Model 503dr Hydroprobe). The results for the first two years of the study can be found in Blowes et al. (1995b) and are briefly outlined below. After 18 months, seepage from the total tailings lysimeter pit had a low pH and elevated concentrations of dissolved Ni, Fe and S0 4 2\ The Ni and Fe concentrations were almost an order of magnitude higher in the total tailings seepage than in the main and low sulfur tailings pits. The values for these concentrations after 18 months were comparable to the column oxidation experiments after approximately 600-700 mm of cumulative rainfall. The main tailings showed slightly acidic conditions in the unsaturated zone, and neutral conditions in the saturated zone. The low sulfur tailings recorded neutral 25 pH conditions in both the unsaturated and the saturated zones. As expected, the pH increased with increasing depth in all three lysimeters. The 0 2 concentrations in the lysimeters were used to calculate the sulfide-oxidation rate, using the 0 2 gas flux calculated from the measured 0 2 and estimated 0 2 gas-diffusion coefficients derived from the semi-empirical equation of Reardon and Moddle (1985). The results can be seen in table 3.2. The rate is greater in the main tailings than it is in the total tailings probably as a result of the lower average moisture content in the unsaturated zone of the main tailings. The low sulfur tailings has a much lower oxidation rate than either of the other two tailings types. Field Lysimeter Oxygen Flux Sulfide Oxidation Rate (mol/m2/day) (kg/m2/year) Low Sulfur Tailings 0.21 0.98 Main Tailings 1.70 7.97 Total Tailings 1.01 4.73 Table 3.2: Sulfide oxidation rates for the three field lysimeters. After Stuparyk et al. (1995). 26 4.0 SAMPLE COLLECTION AND PREPARATION 4.1 Sample Collection Sampling for the mineralogical examination took place in October, 1995. The lysimeters were cored vertically with 5 cm diameter aluminum tubes bottom-capped with iris cups to secure the tailings as the cores were extracted from the pits. Two cores were taken in each lysimeter, one where the surface of the tailings was dry and the other where the surface was wet. The core interval extended to the approximate depth of the lysimeters, ensuring that the liner was not punctured. Cored sites were within 1 meter of piezometers previously emplaced in the pits, and are shown in figure 4.1. Low Sulfur Tailings (0.5 w(% S) Main Tailings (1.0wt%S) Total Tailings (2.5 wt% S) WMmMMMi i l i i i i i i l l l i lillB :" llWlllllllIllllliî lillllll̂ ^W illll llllllillillllli - mm I l l l •mm 10.4 m © 5 cm diameter core sampling site Figure 4.1 Schematic representation of the field lysimeter test pits showing core sample locations: LST-1, MT-1, and TT-1 = core sites where the surface of the tailings was dry; LST-2, MT-2, and TT-2 = core sites where the surface of the tailings was wet. 27 The laboratory oxidation columns were cored using, 2.5 cm diameter stainless steel pipes equipped with iris cups on one end. The tubes were driven vertically through the centre of the columns to the depth of the sand layer. Figure 4.2 is a schematic representation of the oxidation column and the sampling core. 65 cm 20 cm 2.5 cm diameter stainless steel core PVC column Tailings N2 101.3 Kpa I t Quartz sand Figure 4.2 Representation of the laboratory column oxidation experiment with sampling core. After Stuparyk etal. (1995). 4.2 Sample Preparation After coring, the samples were frozen to prevent reactions between the tailings and the core barrel, and to minimize any bacterially catalyzed reactions within the tailings. While frozen, the cores were split along their lengths, half was retained frozen as reference material, and the other half was thawed and dried at room temperature. Megascopic characterization of the cores took place at this time, including grain size 28 classification and colour indexing of the tailings using Munsell's soil colour chart. The results are presented in appendix C. Sub-samples of the tailings (approximately 90 in total) were taken at various depths throughout each core. Sampling was more closely spaced in the unsaturated zone than in the saturated^zone of the tailings. These sub-samples were then split; half was kept for x-ray analysis and the other half was used for polished thin sections for optical and scanning electron microscopy and electron probe microanalysis. Preparation of the polished thin sections was done in a non-aqueous medium to preserve any soluble phases present in the tailings. 29 5.0 QUALITATIVE ANALYSIS: MINERAL IDENTIFICATION AND TEXTURAL CHARACTERIZATION OF THE LOW SULFUR TAILINGS, MAIN TAILINGS, AND TOTAL TAILINGS Characterization of the three tailings types included mineralogical identification of primary phases and alteration products, with emphasis on the alteration products and resulting textures. Potentially acid- generating and acid-neutralizing minerals were closely examined for evidence of oxidation or dissolution. Powder x-ray diffractometry and optical microscopy were completed on samples from each of the three tailings types from the lysimeters and the oxidation columns. Powder x-ray diffraction analyses of dried, powdered tailings samples were carried out on a Siemens D5000 powder x-ray diffractometer with a graphite monochromator, Cu Ka radiation, a voltage of 40 kV and a current of 30 mA. The samples were scanned from 3° to 60° 29 in steps of 0.02° 29 per 0.8 seconds. The petrographic characterization of the tailings mineralogy and textures was accomplished using a Nikon SMZ-1 OPTIPHOT2-POL stereoscopic microscope. Photomicrographs were taken using a microflex AFX-DX attachment and a Nikon FX-35DX camera. 30 5.1 Powder X-ray Diffractometry 5.1.1 Field lysimeter test pits X-ray diffractometer patterns for samples from the field lysimeters are shown in figures 5.1,5.2 and 5.3 for the low sulfur tailings, main tailings and total tailings respectively. The mineral content is similar in all three tailings types and consists of: • quartz [Si02] • feldspar (anorthite [CaAl2Si2Os]-albite [NaAlSi308]) • mica (biotite [K(Mg,Fe2+)3(Al,Fe3+)Si3O10(OH,F)2]) • amphibole (hornblende [Ca2(Fe2+,Mg)4Al(Si7Al)022(OH,F)2]-actinolitic hornblende [Ca2(Fe2+,Mg)5Sis022(OH)2]) • chlorite [(Mg,Fe2+)5Al(Si3Al)O10(OH)s] • pyroxene [ABSi206; where A = Ca, Na, Mg, or Fe2+; and B = Mg, Fe2+ ,Fe3+ ,Cr , Mn, or Al.] Secondary minerals detected by x-ray diffractometry in the lysimeters include gypsum [CaS042H20] in samples from the main tailings (at depths of 10, 25 and 50 cm), and goethite [FeO OH] in the near surface samples, to a depth of 5 cm, from both the main tailings and total tailings. The gypsum is interpreted to have precipitated, in part from sulfate-rich waters available from the oxidation of pyrrhotite, as well as from mill process waters co-deposited with the tailings. The identification was confirmed by the disappearance of the gypsum peaks in the x-ray diffractogram after the sample had been washed in distilled water. Goethite is likely derived directly from sulfide oxidation. A peak corresponding to montmorillonite [(Na,Ca)o.3(Al,Mg)2Si40io(OH)2nH20] is also seen in the x-ray diffraction spectra from various depths in all three tailings types. It is not certain whether the montmorillonite is primary or secondary in nature. d V A L U E (A) 31 S A M P L E DEPTH (cm) 1.541 2.5 5.0 10.0 25.0 45.0 4̂J if. 85.0 0.00 20.00 40.00 D E G R E E S 2-THETA 60.00 Figure 5.1: Powder x-ray diffraction patterns for samples from various depths in the low sulfur tailings lysimeter pit. d VALUE (A) S A M P L E D E P T H (cm) 3.838 4.436 3 s 2.5 5.0 10.0 25.0 50.0 90.0 0.00 20.00 40.00 D E G R E E S 2-THETA 32 2.976 2.252 1.823 1.541 60.00 Figure 5.2: Powder x-ray diffraction patterns for samples from various depths in the main tailings lysimeter pit. S A M P L E DE PTH (cm) 2.5 5.0 10.0 J 20.0 I 50.0 100.0_ d V A L U E (A) 33 838 I 4.436 u U 2.976 2.252 1.823 1.541 0.00 20.00 40.00 D E G R E E S 2-THETA 60.00 Figure 5.3: Powder x-ray diffraction patterns for samples from various depths in the total tailings lysimeter pit. 34 5.1.2 Laboratory oxidation columns X-ray diffraction patterns for the samples taken from the low sulfur tailings, main tailings and total tailings oxidation columns are given in figures 5.4, 5.5, and 5.6. As in the lysimeter pits, these tailings samples are predominantly comprised of: • quartz [Si02] • feldspar (anorthite [CaAl2Si208]-albite [NaAlSi308]) • mica (biotite [K(Mg,Fe2+)3(Al,Fe3+)Si3O10(OH,F)2]) • amphibole (hornblende [Ca2(Fe2+,Mg)4Al(Si7Al)022(OH,F)2]-actinolitic hornblende [Ca2(Fe2+,Mg)5Si8022(OH)2]) • chlorite [(Mg,Fe2+)5Al(Si3Al)Oi0(OH)8] • pyroxene [ABSi206; where A = Ca, Na, Mg, or Fe2+; and B = Mg, Fe2+ ,Fe3+ ,Cr , Mn, or AL] The secondary minerals detected in the oxidation columns also include gypsum and goethite, as well as jarosite [KFe33+(S04)2(OH)6], and a vermiculite-type clay mineral [(Mg,Fe2+,Al)3(Al,Si)4Oio(OH)24H20]. Gypsum was not detected in the low sulfur tailings column, but is seen in the main tailings and total tailings. The relative abundance of gypsum is greater in near surface samples in both tailings types, but it is also detected below the 40 cm depth in both cases. Gypsum from the upper portion of the columns likely precipitated from solutions generated by sulfide oxidation, but that found below the oxidized zone is interpreted to have precipitated from mill process-waters present in the tailings when initially deposited in the columns. Goethite is present in samples from the upper 15 cm of the total tailings column and is presumably a direct result of sulfide oxidation. Jarosite is also seen near the surface of the total tailings column and is believed to have precipitated from solutions saturated with iron and sulfate. Vermiculite is detected in the upper section of the main tailings and total tailings columns, and has resulted from biotite alteration. Montmorillonite [(Na,Ca)03(Al,Mg)2Si4O|0(OH)2nH2O] was detected in all three tailings types in the oxidation column, but as in the field lysimeters, its origin is not obvious. d VALUE (A) 35 S A M P L E DEPTH (cm) 2.5 7.5 15.0 40.0 60.0 $8 4.436 lb* I i i i i >.976 2.252 1.823 1.541 W 0.00 20.00 40.00 D E G R E E S 2-THETA 60.00 Figure 5.4: Powder x-ray diffraction patterns for samples from various depths in the low sulfur tailings oxidation column. S A M P L E D E P T H (cm) 2.5 7.5 15.0 40.0 60.0 d VALUE (A) 36 \1 V4j 838 I 4.436 2.976 2 I 0.00 2.252 1.823 I 1.541 20.00 40.00 D E G R E E S 2-THETA 60.00 Figure 5.5: Powder x-ray diffraction patterns for samples from various depths in the main tailings oxidation column. d V A L U E (A) 37 S A M P L E D E P T H (cm) 2.5 7.5 15.0 40.0 60.0 1.541 0.00 20.00 40.00 D E G R E E S 2-THETA 60.00 Figure 5.6: Powder x-ray diffraction patterns for samples from various depths in the total tailings oxidation column. 38 5.2 Petrography 5.2.1 Identification of primary minerals The primary minerals identified by microscopic examination of the polished thin sections in transmitted and reflected light include approximately 20% quartz, 35% feldspar (primarily albite and anorthite with minor potassium feldspar), 15% amphibole (mainly hornblende with smaller amounts of actinolite), 10% chlorite, 10% mica (biotite-phlogopite), 5% clinopyroxene, 2% orthopyroxene, and minor apatite as well as pyrrhotite, magnetite, ilmenite, chalcopyrite, pentlandite, and trace pyrite. The opaque minerals constitute <_5% of the samples. Estimations of the mineralogical modal abundance for each of the polished thin sections examined are tabulated in appendix D and are graphically illustrated in figures 5.7 through 5.10. Optical variations within one mineral type are most pronounced for hornblende, chlorite, and biotite. Hornblende varies from dark green to brownish green in colour and is more strongly pleochroic in the dark green variety. Light green chlorite is more abundant than dark green chlorite, but both types exist in the tailings. Colour variations are most strongly pronounced in biotite, which varies from dark brown to yellowish brown to greenish brown. Zoning within individual biotite grains is common in the lighter coloured biotite. The abundance of pyrrhotite varies between the three tailings types and is the main difference with respect to primary mineralogy. The low sulfur tailings contain approximately 1% pyrrhotite in the unoxidized zone, whereas the main tailings contain between 2 and 3%, and the total tailings range from 4 to 39 5% pyrrhotite. Pyrrhotite is also the only mineral that shows significant variation with depth in the tailings, and in general is less abundant near the surface of the tailings and gradually increases in abundance downwards. This trend is most pronounced in the main tailings and total tailings oxidation columns. < (% aAiivnaa) 30NvaNnavivaow < (% 3AI1V13H) aoNVQNnav ivaow < (% 3AllV13d) 30NvaNnav i v a o w (% 3Aiiv~iaa) 30NVQNn8V Tvaow 44 5.2.2 Characterization of silicate alteration Two silicate minerals exhibit obvious signs of alteration in the Inco Ltd. tailings, namely biotite and plagioclase feldspar. The alteration of biotite is not seen optically in the low sulfur tailings or main tailings, but is evident in the total tailings lysimeter and oxidation column. Weak pleochroism and bleached colour are evidence of this type of alteration. The photomicrographs, taken at 90° to each other to show the loss of pleochroism, given in figures 5.11a and 5.11b represent the degree of alteration typical for biotite in the total tailings lysimeter. The biotite alteration in the oxidation column is more intense; no colour or pleochroism remains in the example shown in figure 5.12a and 5.12b, and the grain is coated with a secondary phase, probably an iron oxyhydroxide. Plagioclase alteration consists of saussuritization both within the grain and around the grain edges. The alteration evident within the grain is interpreted to have occurred before deposition in the lysimeters or in the columns, and that around the grain's edges to have followed deposition (figure 5.13). Plagioclase alteration is apparent in all three tailings types, but has not progressed beyond the stage represented in the photomicrograph. 5.2.3 Characterization of sulfide oxidation The sulfide minerals in the Copper Cliff tailings that show evidence of oxidation are primarily pyrrhotite with minor pentlandite and chalcopyrite oxidation. Figure 5.11: A: photomicrograph of altered biotite from the total tailings field lysimeter; B: photomicrograph taken perpendicular to A to show pleochroism. Scale bar equals 100 micrometres. Figure 5.12: A: photomicrograph of altered biotite from the total tailings oxidation column; B: photomicrograph taken perpendicular to A to show plcochroism. Scale bar equals 50 micrometres. 47 A sulfide alteration index (S.A.I.), modified from Blowes and Jambor (1990), was assigned to each sample and plotted against depth. The index is based on a relativity scale ranging from 0 to 10. Table 5.1 outlines the characteristics used to assign a value to each sample, and figure 5.14 shows the sulfide alteration index profiles for the field lysimeters and the oxidation columns. The maximum depth of oxidation is estimated at the point where the curves flatten and begin to approach an S.A.I. = 0; i.e., at approximately 30 to 50 cm below surface in the low sulfur tailings lysimeter, 30 to 50 cm in the main tailings lysimeter, 40 to 50 cm in the total tailings lysimeter, 15 to 20 cm in the low sulfur tailings column, 30 to 40 cm in the main tailings column, and 45 to 60 cm in the total tailing column. NUMERICAL SCALE DESCRIPTION OF DEGREE OF SULFIDE OXIDATION 10 Pyrrhotite and pentlandite completely obliterated, traces of pyrite and chalcopyrite may still be visible. 9 Pyrrhotite is absent, but pentlandite may be present with thick alteration rims. 8-7 Trace amounts of pyrrhotite may be seen as surviving cores in a pseudomorhpic replacement; pentlandite still rimmed. 6-4 Pyrrhotite grains have broad alteration rims (thinning from scale 6 to scale 4), often multi-phase. Pentlandite grains may have thin rims (at scale 6) or show slightly altered edges (at scale 4). 4-2 Rims surrounding pyrrhotite thin as scale grades down to 2, many grains appear unaltered. Pentlandite appears fresh. 1-0 Very few grains of pyrrhotite will appear altered at an index of 1, usually along fractures or discontinuously at grain margins. At a scale of 0, all the grains are pristine. Table 5.1: Sulfide alteration index based on a numerical scale. After Blowes and Jambor (1990). The oxidation of pyrrhotite in the tailings is typically manifested by various degrees of pseudomorphic replacement by secondary phases. This replacement initially occurs by penetration along fractures, partings, and grain boundaries, advances to a stage in which only residual sulfides remain, and culminates in complete pseudomorphism. Examples of the various degrees of alteration are discussed below and are described with reference to the tailings type and location. 48 Figure 5.14: Sulfide alteration index (S.A.I.) versus depth: A: low sulfur tailings lysimeter (dry surface); B: low sulfur tailings lysimeter (wet surface); C: low sulfur tailings column; D: main tailings lysimeter (dry surface); E: main tailings lysimeter (wet surface); F: main tailings column; G: total tailings lysimeter (dry surface); H: total tailings lysimeter (wet surface); I: total tailings column. The photomicrograph given in figure 5.15 is an example of an oxidized pyrrhotite grain from the unsaturated zone of the low sulfur tailings lysimeter, and is representative of the highest degree of oxidation seen in the low sulfur tailings. Alteration has progressed via replacement along the parting Figure 5.15: Pyrrhotite oxidation, primarily along the parting plane of a grain from the low sulfur tailings lysimeter. Scale bar equals 200 micrometres. plane by a relatively homogeneous iron oxyhydroxide phase, which is typically soft and bluish grey in colour, but remnant pyrrhotite still exists. The bright grey mineral adjacent to the altered pyrrhotite is magnetite typical of the magnetite in all three tailings types, and the two reddish grey ilmenite grains, seen in the upper left corner of the figure, are representative of the ilmenite seen throughout the tailings. The grain of pyrrhotite illustrated in figure 5.16 has undergone preferential replacement along its parting plane by an iron oxyhydroxide showing similar alteration to that described above. This sample is taken from the unsaturated zone of the main tailings lysimeter. Another example of pyrrhotite oxidation, also from the main tailings lysimeter, has resulted in three alteration products (figure 5.17). The bulk of the replacement has occurred in the core of the grain by a very soft phase, with bright yellow internal reflections, that is assumed to be predominantly native sulfur. The fracture running through the centre of the grain, and those perpendicular to it on the left side of the grain, are lined by bluish grey iron oxyhydroxide. Covellite, easily identified by its characteristic bright blue colour, is intermixed with the iron oxyhydroxide at the top of the perpendicular fractures and as a solitary grain adjacent to the pyrrhotite. As the degree of oxidation increases, less primary pyrrhotite remains. A few remnant shreds of pyrrhotite can still be seen in the example of nearly complete pseudomorphic replacement from the unsaturated zone of the main tailings lysimeter (figure 5.18). The pseudomorphic material is heterogeneous, possibly comprised of two or more phases whose different hardnesses result in a complex topography. The predominant phase is an iron oxyhydroxide with red internal reflections as seen under crossed polars (figure 5.18b). 51 Figure 5.16: Pyrrhotite oxidation occurring along the parting plane in a grain from the main tailings lysimeter. Scale bar equals 50 micrometres. Figure 5.17: Oxidized pyrrhotite from the main tailings lysimeter resulting in replacement in the core of the grain by native sulfur, and along fractures by iron oxyhydroxide and covellite. Scale bar equals 50 micrometres. 52 Figure 5.18: Photomicrograph of nearly complete pseudomorphic replacement of pyrrhotite: A: taken with reflected light; B: under crossed polars to show red internal reflections of secondary alteration product. Scale bar equals 50 micrometres. 53 The degree to which the oxidation of pyrrhotite has progressed is greatest in the total tailings lysimeter, typically resulting in thick, multi-phase rims and complete pseudmorphism. The oxidation rims, like that seen in figure 5.19, are often composed of native sulfur and iron oxyhydroxide. The native sulfur, because it is so brittle, is often partially lost when the samples are polished, but typically occurs directly adjacent to remnant pyrrhotite or in the core of the pseudomorph, and is rimmed by iron oxyhydroxide which partly protects the sulfur. The pseudomorphic replacement in figure 5.20 is a fine grained mixture of two secondary phases in which vestigial textures of the pyrrhotite parting are preserved. Although, most pseudomorphs exhibit this texture, the pseudomorph in figure 5.21 does not. In reflected light, the grain appears relatively homogeneous (figure 5.21a); in transmitted light, however, native sulfur, transparent and yellow, and intermixed iron oxyhydroxide, red in colour, are evident (figure 5.21b). A concentric zoning-type texture adopted by the iron oxyhydroxide is likely a result of replacement of a shrinking pyrrhotite core, where the native sulfur now exists. The alteration of pyrrhotite in the oxidation columns produced secondary phases and textures similar to those produced in the field lysimeters with the exception of a leached texture. Leaching resulted in grains with deeply embayed edges (figure 5.22) and is seen sporadically throughout the oxidized zone of each of the three oxidation columns. Complete oxidation of pyrrhotite has not occurred in the low sulfur tailings oxidation column, but is commonly seen in both the main tailings and the total tailings columns. Figure 5.23 is an example from the main tailings column which shows the replacement of pyrrhotite by at least one type of iron oxyhydroxide. The larger pseudomorph, seen in the lower half of the grain, exhibits red internal reflections typical of iron oxyhydroxides. It is cemented to grains of altered pentlandite, the mottled cream coloured grains, by an iron oxyhydroxide cement. Figure 5.20: Pyrrhotite pseudomorph exhibiting vestigial texture of pyrrhotite parting plane, from the total tailings lysimeter. Scale bar equals 50 micrometres. Figure 5.21: Pseudomorph after pyrrhotite, with a remnant ilmenite inclusion, at the depth of maximum oxidation in the total tailings lysimeter: A: as seen under reflected light; B: taken in transmitted light to show the yellow core of native sulfur and red iron oxyhydroxide. Scale bar equals 100 micrometres. Figure 5.23: Iron oxyhydroxide pseudomorphs after pyrrhotite cemented to grains of weakly altered pentlandite (cream coloured) by iron oxyhydroxide. Scale bar equals 50 micrometres. 58 Figures 5.24a and 5.24b are photomicrographs of a pseudomorph from the total tailings oxidation column. The pseudmorph consists of a core of intermixed iron oxyhydroxide and sulfur, likely as sulfate, and an outer rim of iron oxyhydroxide. The area separating the core and the rim is a void which was likely occupied by native sulfur. The red internal reflections of the iron oxyhydroxide are prominent in the photomicrograph taken under crossed polars, both in the pseudomorph and in the fine grained particles coating nearby grains. Alteration of pentlandite, another source of potential acid-generation and metal contamination, is also evident in the Copper Cliff tailings. There are primarily two modes of alteration, the formation of oxidation rims, and nonpreferrential replacement that creates a mottled texture. The oxidized pentlandite grain in figure 5.25 is from the main tailings lysimeter. Oxidation has progressed around the grain's edge and along a crack in the lower central portion of the grain. Two phases are present, a grey phase, most likely an iron oxyhydroxide, and a light pink phase that comprises the bulk of the oxidation. The grain in the figure below it (figure 5.26) also exhibits an oxidation rim, but is composed of only one phase, an iron oxyhydroxide. The second alteration texture seen in pentlandite is exhibited by the grain in figures 5.27a and 5.27b. The secondary phase in this case is also an iron oxyhydroxide, with red internal reflections. Because replacement has not been crystallographically controlled, the result is a mottled appearance of the mineral's surface. Pentlandite alteration in the oxidation columns is comparable to that in the field lysimeters, but as seen with pyrrhotite, has progressed further in the columns. Figure 5.28 is an example from the low sulfur 59 tailings column. The two secondary phases evident here are reminiscent of the example from the main tailings lysimeter shown in figure 5.25. Figure 5.24: Pyrrhotite pseudomorph from the total tailings oxidation column: A: under reflected light; B: under crossed polars. Scale bar equals 50 micrometres. Figure 5.26: Relatively homogeneous iron oxyhydroxide oxidation rim surrounding pentlandite grain from the main tailings lysimeter. Scale bar equals 50 micrometres. Figure 5.27: Nonpreferrential replacement of pentlandite by an iron oxyhydroxide resulting in a mottled texture, the grain came from the main tailings lysimeter. A: seen using reflected light; B: same photomicrograph under crossed polars. Scale bar equals 50 micrometres. 63 Pyrite, although a minor sulfide constituent in the Copper Cliff tailings, is another potential acid- generating mineral of concern in many sulfide rich mine waste environments. Figure 5.29 shows pyrite coexisting with pyrrhotite in the total tailings lysimeter. The pyrrhotite exhibits slight oxidation, but because the grain edges remain relatively sharp, the oxidation may have occurred prior to deposition in the tailings. The pyrite grain boundaries and surface are unaltered, indicating a slower oxidation rate than pyrrhotite. Chalcopyrite also oxidizes more slowly than pyrrhotite in the tailings. Figure 5.30 is an example of oxidized pyrrhotite directly adjacent to an unoxidized chalcopyrite grain which exhibits sharp boundaries and fractures. This relationship is typical for all three tailings types in the field lysimeters, and in the low sulfur tailings oxidation column; however, oxidation in the main tailings and total tailings columns has progressed to the stage where chalcopyrite dissolution is apparent (figure 5.31). In this case, covellite has precipitated in the hole created from the dissolution of the chalcopyrite inclusion. The presence of covellite is most pronounced in the total tailings lysimeter and oxidation column at the maximum depth of oxidation, referred to here as the accumulation zone, as defined in Jambor and Owens (1993). Sporadic grains of covellite are also evident in the main tailings, but to a lesser extent. Covellite is easily identified by its bright blue colour in reflected light (figure 5.32a), and fiery red anisotropism seen under crossed polars (figure 5.32b). Figure 5.29: Prc-deposition oxidation of pyrrhotite coexisting with pyrite in the total tailings lysimeter. Scale bar equals 50 micrometres. Figure 5.31: Leached chalcopyrite inclusion and secondary covellite from the total tailings oxidation column. Scale bar equals 100 micrometres. Figure 5.32: Secondary covellite in the total tailings lysimeter at the greatest depth of oxidation: reflected light; B: under crossed polars. Scale bar equals 50 micrometres. A: in 67 5.2.4 Characterization of slag particle alteration In the more strongly oxidized samples, many slag particles have been altered and, although volumetrically of less concern than the sulfides, the alteration merits discussion here. Table 5.2 outlines the alteration index used for slag particle oxidation. The index was modeled after that for sulfides given above. There are not enough slag particles in the cores to justify a slag alteration depth profile; however, an average numerical value has been assigned to the oxidized zone of each of the lysimeters and oxidation columns based on the scale outlined below. The slag alteration index assignments are given in table 5.3. NUMERICAL SCALE DESCRIPTION OF DEGREE OF SLAG PARTICLE ALTERATION 10 All slag particles have been completely replaced by secondary products; rims are evident, and the presence of encircling secondary phases is pervasive (commonly covellite and iron oxyhydroxides). 9 A few remnants of the original slag particles can be seen, usually in the core of the particle. The term "original" may include alteration products formed before deposition in the tailings environment. 8-7 Nearly all the original slag particles show replacement of between 70% and 80% of their bulk. 6-4 Much of the original slag can be seen, many of the particles are surrounded with rims of various thicknesses, and are encircled by associated secondary phases. 4-2 Rims surrounding slag particles are thin and often discontinuous. 1 Slag particles show only thin rims, if at all; some have associated covellite and iron- oxyhydroxide grains on their periphery. 0 No evidence of secondary alteration having occurred in the tailings; many of the particles may show alteration and replacement textures that occurred before deposition. Table 5.2: Slag alteration index based on a numerical scale. The degree to which slag particle oxidation has occurred varies with the tailings type, but is not significantly different between the same tailings in the lysimeter and its corresponding oxidation column. 68 SAMPLE NUMERICAL SLAG ALTERATION INDEX Low Sulfur Tailings lysimeter 0 Main Tailings lysimeter 1 Total Tailings lysimeter 2-4 Low Sulfur Tailings oxidation column 0 Main Tailings oxidation column 1 Total Tailings oxidation column 4 Table 5.3: Slag alteration indices for the oxidized zones of each of the lysimeters and oxidation columns. The slag particle seen in figure 5.33 shows the first signs of oxidation. The particle is slightly corroded around the edges and along fractures. The circular cream coloured particle is more strongly etched than the rest of the grain. As alteration progresses, covellite association increases. The tear-drop shaped slag particle in figure 5.34 contains, within its interior, covellite that may have formed due to replacement prior to tailings deposition. As well, covellite that formed after deposition in the tailings occurs as small separate grains surrounding the slag particle. Oxidation rims are another prevalent oxidation texture seen on many slag particles. Figure 5.35 is a photomicrograph of a slag particle that was partly replaced by covellite before deposition in the tailings, and was surrounded by a light grey oxidation rim after deposition in the tailings. Figure 5.36 also shows a slag particle with a well developed oxidation rim. The core of the particle is heterogeneous and the bulk of the original grain has been lost either by dissolution in the tailings or when the sample was polished. Figure 5.34: Altered slag particle, from the total tailings lysimeter. surrounded by secondary covellite. Scale bar equals 50 micrometres. 70 Figure 5.35: Slag particle that may have been altered to covellite before deposition in the tailings, and has formed an oxidation rim after deposition in the tailings. Scale bar equals 50 micrometres. Figure 5.36: Oxidation rim around an altered particle slag from the total tailings lysimeter. The core cither dissolved or was plucked out when the section was polished. Scale bar equals 50 micrometres. 71 5.3 Chapter Summary The primary mineralogy is grossly similar among the three tailings types. The principal difference is in the abundance of pyrrhotite, i.e., 1% of the low sulfur tailings, 2 to 3% of the main tailings, and 4 to 5% of the total tailings. In general, the amount of pyrrhotite, which is the most prominent potentially acid- generating mineral in the tailings, decreases with depth in the lysimeters and in the columns, as a result of oxidation. The oxidation of pyrrhotite is most pronounced in the total tailings, followed by the main tailings, and is weakest in the low sulfur tailings. Oxidation is more strongly developed in the oxidation columns than in the field lysimeters, but has penetrated to a greater depth in the lysimeters than in the columns. The process of pyrrhotite oxidation begins with replacement by secondary phases along fractures, partings, and grain boundaries, continues until only residual pyrrhotite remains, and results in complete pseudomorphic replacement. The secondary minerals commonly detected include iron oxyhydroxides, native sulfur, and covellite, as well as residual sulfur, likely as sulfate. Leached grains of pyrrhotite, lacking associated secondary products, are seen in the columns, but are absent in the lysimeters. Pentlandite alteration is visible in all three tailings types, but is most pronounced in the more strongly oxidized main tailings and total tailings. It typically results in pronounced oxidation rims, and network-type replacement resulting in a mottled texture. Other secondary' phases detected include gypsum, jarosite, and vermiculite. These alteration products are most abundant in the near surface samples of the main tailings and total tailings columns, but are subordinate with respect to the secondary phases resulting from direct replacement of pyrrhotite. No carbonates were observed in the Copper Cliff tailings, but the alterations of plagioclase and biotite are evident, and these minerals may provide some neutralization potential. 6.0 QUALITATIVE ANALYSIS: MINERAL IDENTIFICATION AND TEXTURAL CHARACTERIZATION OF THE PYRRHOTITE-RICH TAILINGS 72 An oxidation column containing pyrrhotite-rich tailings (approximately 14 wt. % S) was set up in conjunction with the low sulfur tailings, main tailings, and total tailings columns in 1993, and was cored in the fall of 1995 when the other columns were sampled. The pyrrhotite-rich tailings are representative of the pyrrhotite reject stream of tailings produced in the mill. Because of their high sulfur content, they are not being considered by Inco as a possible cover material, and they do not constitute a fundamental component of this study. However, powder x-ray diffraction analyses and optical microscopy were carried out on samples from the pyrrhotite-rich column for comparison, and the results are briefly discussed in this chapter. 6.1 Powder X-ray Diffractometry Powder x-ray diffraction analyses were done using the same operating conditions and running time as is outlined in chapter 5 for the analysis of the low sulfur tailings, main tailings and total tailings products. Figure 6.1 gives the diffraction spectra for five samples taken from various depths in the pyrrhotite-rich tailings column. The primary minerals identified on the diffractogram are: • quartz [Si02] • feldspar (anorthite [CaAl2Si208]-albite [NaAlSi308]) • mica (biotite [K(Mg,Fe2 +)3(Al,Fe3 +)Si3O,0(OH,F)2]) • amphibole (hornblende [Ca2(Fe2+,Mg)4Al(Si7Al)022(OH,F)2]-actinolitic hornblende [Ca2(Fe2 +,Mg)5Si802 2(OH)2]) 73 • chlorite [(Mg,Fe2+)5Al(Si3Al)O10(OH)8] • pyroxene [ABSi206; where A = Ca, Na, Mg, or Fe2+; and B = Mg, Fe2+ ,Fe3+ ,Cr , Mn, or Al.] The secondary minerals detected in the pyrrhotite-rich tailings include gypsum [CaS042H20], goethite [FeO OH], and jarosite [KFe33+(S04)2(OH)6]. The strongest intensity peak for gypsum (approximately 7.6 A) is very prominent in the sample from 2.5 cm depth, loses intensity at depths of 7.5 and 10 cm, is not present in the sample from 20 cm below the surface, and is very small in the bottom-most sample. The gypsum in the upper portion of the column is interpreted to have precipitated from sulfate rich waters resulting from sulfide oxidation. The gypsum seen at the bottom of the column is interpreted to have precipitated from mill process-waters also saturated with respect to sulfate. Goethite and jarosite are detected in the samples above 20 cm and likely formed due to sulfide oxidation taking place in the column. Secondary vermiculite associated with the breakdown of biotite is not evident in the pyrrhotite-rich tailings. 6.2 Petrography 6.2.1 Identification of primary minerals Polished thin sections were made from splits of the samples analyzed by x-ray diffractometry. Mineralogical modal abundances for each section were approximated and are given in appendix D, and a graphical representation of modal abundance versus depth in the column has also been included (figure 6.2). The primary minerals identified during petrographic examination include quartz, feldspar (predominantly plagioclase with minor potassium feldspar), biotite, chlorite, hornblende, actinolite, orthopyroxene and clinopyroxene, pyrrhotite, pentlandite, chalcopyrite, pyrite, magnetite, and ilmenite. d VALUE (A) 8.838 4.436 2.976 2.252 1.823 1.541 20.00 40.00 60.00 D E G R E E S 2-THETA Figure 6.1: Powder x-ray diffraction patterns for samples from various depths in the pyrrhotite-rich tailings oxidation column. Figure 6.2: Mineralogical modal abundance versus depth in the pyrrhotite-rich tailings oxidation column. 76 Pyrrhotite, chalcopyrite, and pentlandite show a weak trend of increasing abundance with depth, likely a reflection of sulfide oxidation. 6.2.2 Characterization of sulfide alteration A sulfide alteration index depth profile for the pyrrhotite-rich tailings column is given in figure 6.3. It is based on the relative scale used to assign alteration indices to the low sulfur tailings, main tailings and total tailings in section 5.2.3. 0 n 2 S.A.I 4 6 8 10 10 20 T £30 UJ • 40 50 Figure 6.3: Sulfide alteration index versus depth for the pyrrhotite-rich tailings oxidation column. Sulfide alteration in the pyrrhotite-rich tailings has not progressed to the degree seen in the total tailings and main tailings columns, but is comparable to the degree of alteration that has occurred in the low sulfur tailings oxidation column (see figure 5.14). This trend is interpreted to be a reflection of the presence of significant amounts of secondary cementing minerals, which contribute greatly to the cohesion of the tailings and decrease the permeability of the tailings. The cementing phases were identified optically as gypsum, goethite, and minor 77 jarosite, similar to those phases identified by Blowes et al. (1991) in a hard pan formed in the Waite Amulet tailings. The maximum depth of oxidation is approximately 10 cm from the surface of the pyrrhotite-rich tailings, which is less than the three tailings types with lower sulfur concentrations. This is also interpreted to be a result of the presence of abundant secondary cementing phases that decrease the amount of oxygen penetration in the tailings. The oxidation of sulfides in the pyrrhotite-rich tailings follows the same progression as exhibited by the sulfides in the low sulfur tailings, main tailings, and total tailings. Figure 6.4 is a photomicrograph, of material from the oxidized zone of the column, illustrating pyrrhotite oxidation that varies from partial alteration around the edge of a grain (centre of the photomicrograph) to complete pseudomorphism (sporadic throughout the photomicrograph). Prevalent secondary cementing phases are evident in this section, and are likely iron oxyhydroxides. Alteration of pentlandite, typically as narrow oxidation rims, is also apparent in the pyrrhotite-rich tailings (figure 6.5). 6.3 Chapter Summary A pyrrhotite-rich tailings product (approximately 14 wt. % S) that was subjected to the laboratory oxidation tests was qualitatively compared to the tailings from the low sulfur tailings column, main tailings column, and the total tailings column. The primary mineralogy was essentially the same except that the sulfide component of the pyrrhotite-rich tailings was approximately ten times more than in the other three tailings types. The oxidation of pyrrhotite in this column has produced textures similar to those discussed in chapter 5, and has resulted in abundant precipitation of secondary cementing products, identified as gypsum, goethite, and jarosite. The cementing products notably increase the cohesion and decrease the permeability of the tailings, which may slow oxygen penetration into the tailings. Figure 6.4: Altered pyrrhotite (centre of the photomicrograph), coexisting with pseudomorphic replacements after pyrrhotite (approximately 50 micrometers to the right of the pyrrhotite grain), and secondary cementing minerals Scale bar equals 100 micrometers. Figure 6.5: Pyrrhotite and pentlandite alteration at a depth of 7.5 cm from the surface of the pyrrhotite-rich tailings oxidation column. Scale bar equals 50 micrometers. 79 7.0 QUANTITATIVE ANALYSIS AND IMAGING OF THE LOW SULFUR TAILINGS, MAIN TAILINGS AND TOTAL TAILINGS On the basis of petrographic examination, specific grains were chosen for more meticulous examination. Quantitative analysis was done using a C A M E C A SX-50 Electron Probe Microanalyzer (EPMA) and imaging was achieved via scanning electron microscopy (SEM), specifically a Philips X L 30 Scanning Electron Microscope equipped with the Princeton-Gamma-Tech IMIX Energy Dispersion Spectroscopy (EDS)/Image Analysis System. The polished thin sections were carbon coated prior to analysis using an Edwards High Vacuum coating system. Because of the small grain size and heterogeneity of the secondary replacement phases, the Image Analysis System, and in particular the multi-elemental x-ray mapping technique, was used to distinguish phases containing different elements or significantly different amounts of the same elements (see Petruk, 1989). Where possible, identification of secondary oxidation products was confirmed by Debye-Scherrer x-ray film methods. Grain mounts of altered biotites were made and analyzed using a Philips 1830/40 table-top generator, cobalt radiation and an iron filter, run at the operating conditions of 35 kV and 30 mA, and secondary oxidation products resulting from the oxidation of pyrrhotite were sent to the Mineral Sciences Laboratories of Natural Resources Canada, Ottawa, for analysis on a Siemens generator using the same operating conditions. The success of this technique was limited by the small size of the grains, the presence of complex mixtures, and the poor crystallinity of some of the samples. 80 7.1 Quantitative Analysis of Unaltered Minerals Quantitative analysis with the electron probe microanalyzer was done in the wavelength dispersion mode. An accelerating voltage of 15 kV and a beam current of 20 nA were used to analyze the silicates and oxides, the sulfides and their alteration products were analyzed with an accelerating voltage of 20 kV and the same beam current. 7.1.1 Silicates According to Naldrett and Hewis (1984), plagioclase in the Sudbury intrusive complex range in anorthite (An) content from approximately An 6 ] at the base of the South Range norite, to An 5 0 in the quartz gabbro, An, 5 to An2o in the granophyre, and An 2 5 to Aruo in the plagioclase-rich granophyre. EPMA analyses of plagioclase in this study gave compositions ranging from An 7 ! to An 6 (table 7.1). Of the various amphiboles in the tailings, several were chosen to cover a wide range of compositions as inferred from variations in habit, colour and pleochroism seen during petrographic examination. The results (table 7.2) are considered to be representative of the compositional range, and includes actinolite, actinolitic hornblende, ferro-edenitic hornblende, ferro-homblende and ferroan- pargasitic hornblende. The amphiboles are classified here as monoclinic, calcic amphiboles, (Ca + Nae)>1.34 and NaB<0.67, and are further differentiated on the basis of their Si concentration and the Mg/(Mg + Fe) ratio as defined in the paper by Leake (1978). The mica, described in chapter 5 as a biotite-phlogopite, was also analyzed quantitatively, and is concluded to be biotite, sensu stricto. Phlogopite is commonly misinterpreted to be the Mg-rich end- member of the biotite family; however, phlogopite is correctly defined as having formula F content greater Table 7.1: Electron probe microanalysis results for plagioclase feldspar. 1. 2. 3. 4. 5. Si0 2 67.99 51.38 51.26 60.42 61.30 A l 2 0 3 20.86 31.51 31.04 19.84 23.83 Ti0 2 0.02 0.00 0.00 0.02 0.01 FeO 0.04 0.10 0.41 0.10 0.71 C r 2 0 3 0.02 0.00 0.03 0.00 0.00 MgO 0.00 0.01 0.06 0.01 0.25 MnO 0.00 0.00 0.02 0.01 0.02 CaO 1.32 14.23 14.38 3.99 6.38 Na 2 0 10.93 3.56 3.26 8.72 7.60 K 2 0 0.06 0.04 0.05 0.12 0.07 TOTAL 101.24 100.83 100.51 93.23 100.18 S i 4 + 11.76 9.27 9.30 11.45 10.90 A l 3 + 4.25 6.70 6.63 4.43 4.99 T i 4 + 0.00 0.00 0.00 0.00 0.00 Fe 2 + 0.01 0.02 0.06 0.02 0.11 Cr3* 0.00 0.00 0.00 0.00 0.00 Mg 2 + 0.00 0.00 0.02 0.00 0.07 Mn 2 + 0.00 0.00 0.00 0.00 0.00 C a 2 + 0.25 2.75 2.79 0.81 1.22 Na + 3.67 1.25 1.15 3.20 2.62 K + 0.01 0.01 0.01 0.03 0.02 cation sum 19.95 20.00 19.97 19.95 19.92 anion sum 32 32 32 32 32 1 a I bite (An6) 2 anorthite (An67) 3 anorthite (An71) 4 a I bite (An2o) 5 albite (An32) Based on 32 anions Table 7.2: Electron probe microanalysis results for amphiboles, nomenclature was determined based on criteria in Leake (1978). 82 LOW SULFUR TAILINGS 1. 2. 3. 4. 5. 6. Si0 2 47.95 54.39 54.20 53.81 41.68 46.41 A l 2 0 3 3.89 2.98 3.31 1.70 13.44 6.75 Ti0 2 2.05 0.08 0.12 0.08 0.30 0.72 FeO 18.28 11.59 12.02 15.10 23.57 21.65 C r 2 0 3 0.01 0.29 0.34 0.31 0.00 0.00 MgO 10.67 16.21 15.90 14.35 4.79 8.70 MnO 0.49 0.30 0.29 0.47 0.18 0.56 CaO 11.14 12.05 11.80 11.47 11.29 11.19 Na 2 0 0.28 0.33 0.36 0.18 1.36 0.99 K 2 0 0.06 0.01 0.03 0.22 0.65 0.83 F 0.37 0.12 0.13 0.14 0.14 0.38 Cl 0.09 0.10 0.02 0.10 0.66 0.29 H 2 0 * 1.75 2.03 2.04 1.97 1.70 1.71 0=F -0.16 -0.05 -0.05 -0.06 -0.06 -0.16 0=CI -0.02 -0.02 0.00 -0.02 -0.15 -0.07 TOTAL 96.86 100.40 100.50 99.82 99.55 99.96 S i 4 + 7.37 7.73 7.70 7.83 6.46 7.08 A l 3 + 0.70 0.50 0.55 0.29 2.46 1.21 T i 4 + 0.24 0.01 0.01 0.01 0.04 0.08 Fe 2 + 2.35 1.38 1.43 1.84 3.06 2.76 Cr3* 0.00 0.03 0.04 0.04 0.00 0.00 Mg 2 + 2.44 3.43 3.37 3.11 1.11 1.98 Mn 2 + 0.06 0.04 0.04 0.06 0.02 0.07 C a 2 + 1.83 1.84 1.80 1.79 1.88 1.83 Na + 0.08 0.09 0.10 0.05 0.41 0.29 K+ 0.01 0.00 0.01 0.04 0.13 0.16 F" 0.18 0.05 0.06 0.06 0.07 0.18 Cl" 0.02 0.02 0.01 0.03 0.17 0.08 H + 1.80 1.92 1.94 1.91 1.76 1.74 o 2- 23.80 23.92 23.94 23.91 23.76 23.74 cation sum 15.09 15.04 15.04 15.05 15.55 15.46 anion sum 24 24 24 24 24 24 LOW SULFUR TAILINGS 1. actinolitic hornblende 4. actinolite 2. actinolite 5. ferro-edentitic hornblende 3. actinolite 6. ferro-homblende * Determined by stoichiometry H 2 0 calculated assuming 2 (OH",CI",F) Based on 24 anions. Table 7.2.: (Cont'd). MAIN TAILINGS 1. 2. 3. Si0 2 53.30 52.04 49.62 Al 2 0 3 3.36 4.21 7.16 Ti0 2 0.05 0.10 0.22 FeO 14.74 14.56 15.01 Cr 2 0 3 0.02 0.04 0.08 MgO 13.59 13.53 12.43 MnO 0.16 0.00 0.34 CaO 12.60 12.36 11.71 Na 20 0.29 0.38 0.66 K 2 0 0.13 0.11 0.21 F 0.15 0.15 0.11 CI 0.12 0.19 0.22 H 2 0 * 1.97 1.94 1.94 0=F -0.06 -0.06 -0.05 o=ci -0.03 -0.04 -0.05 TOTAL 100.39 99.50 99.61 Si 4 + 7.70 7.59 7.27 Al 3 + 0.57 0.72 1.24 Ti 4 + 0.01 0.01 0.02 Fe 2 + 1.78 1.78 1.84 Cr 3* 0.00 0.01 0.01 Mg 2 + 2.93 2.94 . 2.71 Mn 2 + 0.02 0.00 0.04 C a 2 + 1.95 1.93 1.84 Na + 0.08 0.11 0.19 K+ 0.02 0.02 0.04 F 0.07 0.07 0.05 CI" 0.03 0.05 0.06 H + 1.90 1.88 1.89 o 2- 23.90 23.88 23.89 cation sum 15.06 15.10 15.20 anion sum 24 24 24 MAIN TAILINGS 1. actinolite 2. actinolite 3. actinolitic hornblende * Determined by stoichiometry H 2 0 calculated assuming 2 (OH",CI",F") Based on 24 anions. Table 7.2: (Cont'd). TOTAL TAILINGS 1. 2. 3. 4. 5. Si0 2 50.21 54.52 48.78 41.45 55.08 A l 2 0 3 7.48 2.05 6.25 16.15 0.45 Ti0 2 0.11 0.06 0.48 0.32 0.02 FeO 12.46 21.52 14.78 18.75 23.08 C r 2 0 3 0.01 0.00 0.09 0.00 0.00 MgO 13.67 17.53 12.60 7.00 18.08 MnO 0.24 0.55 0.36 0.24 0.56 CaO 12.11 1.36 11.68 11.52 0.56 Na 2 0 0.70 0.21 0.65 1.37 0.03 K 2 0 0.14 0.14 0.40 0.46 0.01 F 0.03 0.10 0.12 0.17 0.10 CI 0.08 0.10 0.30 0.45 0.07 H 2 0 * 2.03 2.00 1.88 1.79 2.00 0=F -0.01 -0.04 -0.05 -0.07 -0.04 0=CI -0.02 -0.02 -0.07 -0.10 -0.02 TOTAL 99.24 100.08 98.25 99.50 99.98 Si 4 + 7.28 7.88 7.27 6.26 8.00 Al 3 + 1.28 0.35 1.10 2.88 0.08 Ti 4 + 0.01 0.01 0.05 0.04 0.00 Fe 2 + 1.51 2.60 1.84 2.37 2.80 C r * 0.00 0.00 0.01 0.00 0.00 Mg 2 + 2.96 3.78 2.80 1.58 3.92 Mn 2 + 0.03 0.07 . 0.05 0.03 0.07 C a 2 + 1.88 0.21 1.87 1.87 0.09 Na+ 0.20 0.06 0.19 0!40 0.01 K+ 0.03 0.03 0.08 0.09 0.00 F 0.01 0.05 0.06 0.08 0.05 cr 0.02 0.03 0.08 0.12 0.02 H + 1.97 1.93 1.87 1.80 1.94 o 2- 23.97 23.93 23.87 23.80 23.94 cation sum 15.18 14.98 15.25 15.51 14.96 anion sum 24 24 24 24 24 TOTAL TAILINGS 1. actinolitic hornblende 4. ferroan-pargasitic 2. actinolite hornblende 3. actinolitic hornblende 5. actinolite * Determined by stoichiometry H 2 0 calculated assuming 2 (OH",CI",F) Based on 24 anions. 85 than its OH content (Nickel and Nichols, 1991; Fleischer and Mandarino, 1995; Clark, 1993). It can be seen by the results given here (table 7.3) that the F content is well below the OH (by difference) concentrations in all the micas analyzed. The biotite micas analyzed here have Fe:Mg ratios ranging from 1.88 to 0.77. Two dominant chlorite species, ferroan clinochlore and chamosite, have been identified on the basis of electron probe results (table 7.4). The chlorites were assigned names on the basis on their Si content and the Fe/(Fe + Mg) ratio (Hey, 1954). Analyses of a few pyroxenes from the tailings cores (table 7.5) are plotted on a Ca-Mg-Fe ternary diagram (figure 7.1), for comparison with results for pyroxenes Sudbury igneous complex (Scribbins et al, 1984; Pattison, 1979). Most of the pyroxenes analyzed in this study are enstatite, with one possibly representing augite (Morimoto, 1988). The orthopyroxene results closely agree with those from Scribbins et al., but the clinopyroxene analysis does not. Although the cation sum for the augite analysis is low, the result nevertheless was included to show a possible clinopyroxene composition in the tailings. It can be seen on the ternary diagram that the clinopyroxene analyzed here is calcium-poor and iron-rich relative to those from Scribbins et al., and Pattison. The difference is believed to reflect the variation in primary compositions. It has been shown in several papers, for instance Pattison (1979) and Naldrett et al. (1984), that compositions of clinopyroxene and orthopyroxene in the Sudbury complex both vary greatly, commonly depending on distance from the norite contact. Table 7.3: Electron probe microanalysis results for biotite. LOW SULFUR TAILINGS 1. 2. 3. 4. Si0 2 36.56 36.75 36.24 35.06 A l 2 0 3 15.84 16.02 17.73 16.4 Ti0 2 1.54 1.58 1.62 1.71 FeO 17.1 17.2 20.02 19.31 C r 2 0 3 0.08 0.09 0.04 0.07 MgO 12.45 12.51 10.06 9.12 MnO 0.1 0.14 0.14 0.15 CaO 0.01 0.02 0.04 0.03 Na 2 0 0.13 0.11 0.16 0.1 K 2 0 9.66 9.64 9.25 9.29 F 0.51 0.47 0.73 0.74 CI 0.75 0.61 0.92 0.52 H 2 0 * 3.46 3.54 3.35 3.27 0=F -0.21 -0.2 -0.31 -0.31 o=ci -0.17 -0.14 -0.21 -0.12 TOTAL 97.81 98.34 99.79 95.34 Si 4 + 5.63 5.63 5.53 5.60 Al 3 + 2.88 2.89 3.19 3.09 Ti 4 + 0.18 0.18 0.19 0.21 Fe 2 + 2.20 2.20 2.55 2.58 C r * 0.01 0.01 0.01 0.01 Mg 2 + 2.86 2.86 2.29 2.17 Mn 2 + 0.01 0.02 0.02 0.02 C a 2 + 0.00 0.00 0.01 0.01 Na + 0.04 0.03 0.05 0.03 K + 1.90 1.88 1.80 1.89 F" 0.25 0.23 0.35 0.37 c r 0.20 0.16 0.24 0.14 H + 3.56 3.61 3.41 3.49 o 2 - 23.56 23.61 23.41 23.49 cation sum 15.71 15.70 15.62 15.61 anion sum 24 24 24 24 LOW SULFUR TAILINGS 1. biotite 3. biotite 2. biotite 4. biotite * Determined by stoichiometry H20 calculated assuming 4 (OH- ,F- ,CL-) Based on 24 anions. Table 7.3: (Cont'd). MAIN TAILINGS 1. 2. 3. 4. 5. Si0 2 36.07 36.31 35.98 35.87 36.3 A l 2 0 3 16.82 16.78 16.47 16.14 15.88 Ti0 2 1.87 1.77 1.79 1.71 1.69 FeO 19.61 20.18 20.7 20.42 20.06 C r 2 0 3 0.05 0.03 0 0.02 0 MgO 10.21 10.33 10.28 9.95 10.24 MnO 0.2 0.14 0.15 0.1 0.13 CaO 0.04 0.01 0.02 0.09 0.05 Na 2 0 0.06 0.08 0.08 0.16 0.16 K 2 0 9.62 9.71 9.52 9.52 9.52 F 0.12 0.21 0.16 0.57 0.43 Cl 0.56 0.41 0.48 0.6 0.49 H 2 0 * 3.69 3.71 3.69 3.43 3.53 0=F -0.05 -0.09 -0.07 -0.24 -0.18 o=ci -0.13 -0.09 -0.11 -0.14 -0.11 TOTAL 98.75 99.49 99.15 98.2 98.19 S i 4 + 5.56 5.56 5.55 5.59 5.64 A l 3 + 3.06 3.03 2.99 2.96 2.91 T i 4 + 0.22 0.20 0.21 0.20 0.20 Fe 2 + 2.53 2.58 2.67 2.66 2.61 C r * 0.01 0.00 0.00 0.00 0.00 Mg 2 + 2.35 2.36 2.36 2.31 2.37 Mn 2 + 0.03 0.02 0.02 0.01 0.02 C a 2 + 0.01 0.00 0.00 0.02 0.01 Na + 0.02 0.02 0.02 0.05 0.05 K + 1.89 1.90 1.87 1.89 1.89 F" 0.06 0.10 0.08 0.28 0.21 Cl" 0.15 0.11 0.13 0.16 0.13 H + 3.80 3.79 3.80 3.56 3.66 o2- 23.80 23.79 23.80 23.56 23.66 cation sum 15.65 15.68 15.70 15.70 15.68 anion sum 24 24 24 24 24 MAIN TAILINGS 1. biotite 4. biotite 2. biotite 5. biotite 3. biotite * Determined by stoichiometry H20 calculated assuming 4 (OH- ,F- ,CL-) Based on 24 anions. Table 7.3: (Cont'd). T O T A L T A I L I N G S 1. 2. 3. 4. 5. 6. Si0 2 35.07 34.34 35.7 35.96 36.39 36.22 Al 2 0 3 17.4 17.27 16.58 16.57 16.35 16.47 Ti0 2 1.71 1.73 1.71 1.74 1.86 1.76 FeO 23.86 23.7 19.4 19.28 19.43 19.78 Cr 20 3 0.15 0.09 0.07 0 0.08 0.08 MgO 7.11 6.99 10.99 10.64 10.71 10.62 MnO 0.23 0.29 0.15 0.19 0.1 0.14 CaO 0.02 0.02 0.01 0.01 0 0.03 Na20 0.05 0.07 0.1 0.11 0.1 0.08 K 20 9.72 9.51 9.57 9.54 9.39 9.25 F 0.23 0.27 0.38 0.49 0.46 0.35 CI 0.21 0.27 0.37 0.44 0.59 0.6 H 20 * 3.67 3.58 3.6 3.53 3.53 3.57 0=F -0.1 -0.11 -0.16 -0.21 -0.19 -0.15 o=ci -0.05 -0.06 -0.08 -0.1 -0.13 -0.14 TOTAL 99.29 97.96 98.39 98.2 98.66 98.67 Si 4 + 5.49 5.45 5.52 5.56 5.60 5.58 Al 3 + 3.21 3.23 3.02 3.02 2.97 2.99 Ti 4 + 0.20 0.21 0.20 0.20 0.22 0.20 Fe2+ 3.12 3.15 2.51 2.50 2.50 2.55 Cr* 0.02 0.01 0.01 0.00 0.01 0.01 Mg2 + 1.66 1.66 2.53 2.45 2.46 2.44 Mn2 + 0.03 0.04 0.02 0.03 0.01 0.02 Ca 2 + 0.00 0.00 0.00 0.00 0.00 0.01 Na+ 0.02 0.02 0.03 0.03 0.03 0.02 K+ 1.94 1.93 1.89 1.88 1.84 1.82 F" 0.11 0.14 0.19 0.24 0.22 0.17 c r 0.06 0.07 0.10 0.12 0.15 0.16 H + 3.83 3.79 3.72 3.65 3.62 3.67 o 2 - 23.83 23.79 23.72 23.65 23.62 23.67 cation sum 15.68 15.69 15.73 15.68 15.63 15.64 anion sum 24 24 24 24 24 24 T O T A L T A I L I N G S 1. biotite 4. biotite 2. biotite 5. biotite 3. biotite 6. biotite * Determined by stoichiometry H20 calculated assuming 4 (OH- ,F- ,CL-) Based on 24 anions. Table 7.4: Electron probe microanalysis results for chlorites, with nomenclature based on criteria in Hey (1954). LOW SULFUR TAILINGS 1. 2. 3. 4. 5. Si0 2 24.15 24.09 25.23 22.99 27.59 A l 2 0 3 18.34 17.95 22.78 22.1 16.25 T i 0 2 0.3 0.44 0.05 0.05 0.93 FeO 42.95 44.23 24.18 34.53 40.66 C r 2 0 3 0.02 0.04 0.06 0.13 0.04 MgO 1.64 1.48 15.34 7.33 2.77 NiO ND ND ND ND ND MnO 0.21 0.15 0.18 0.38 0.24 CaO 0.03 0.05 0.01 0 0.06 Na 2 0 0.18 0.04 0.02 0.01 0.07 K 2 0 0.23 0.31 0 0 1.78 F 0.04 0.07 0.05 0.09 0.04 Cl 0 0.04 0.09 0.18 0.05 H 2 0 * 10.27 10.26 11.45 10.66 10.67 0=F -0.02 -0.03 -0.02 -0.04 -0.02 o=ci 0 -0.01 -0.02 -0.04 -0.01 TOTAL 98.37 99.11 99.39 98.37 101.12 S i 4 + 5.63 5.61 5.27 5.13 6.18 A l 3 + 5.04 4.93 5.60 5.82 4.29 T i 4 + 0.05 0.08 0.01 0.01 0.16 Fe 2 + 8.37 8.61 4.22 6.45 7.62 Cr3* 0.00 0.01 0.01 0.02 0.01 Mg 2 + 0.57 0.51 4.77 2.44 0.93 Ni 2 + ND ND ND ND ND Mn 2 + 0.04 0.03 0.03 0.07 0.05 C a 2 + 0.02 0.01 0.00 0.00 0.01 Na + 0.08 0.02 0.01 0.00 0.03 K* 0.07 0.09 0.00 0.00 0.51 F" 0.03 0.05 0.03 0.06 0.03 Cl" 0.00 0.02 0.03 0.07 0.02 H + 15.97 15.93 15.94 15.87 15.95 o2- 35.97 35.93 35.94 35.87 35.95 cation sum 19.87 19.90 19.92 19.94 19.78 anion sum 36 36 36 36 36 LOW SULFUR TAILINGS 1. chamosite , 2. chamosite * Determined by stoichiometry 3. ferroan clinochlore H 2 0 calculated assuming 16 (OH" ,F" - C L ) 4. ferroan clinochlore Based on36 anions. 5. chamosite 90 Table 7.4: (Cont'd). MAIN TAILINGS 1. 2. 3. 4. 5. 6. 7. Si0 2 25.11 25.68 25.55 25.15 25.06 25.38 24.72 Al 2 0 3 21.93 20.92 21.29 21.77 21.64 21.6 21.9 Ti0 2 0.08 0.03 0.05 0.06 0.04 0.07 0.07 FeO 26.83 27.01 26.66 26.31 27.28 27.4 26.94 Cr 20 3 0.03 0.01 0.1 0.03 0.03 0.07 0 MgO 13.63 13.91 13.3 13.86 13.78 13.1 13.77 NiO 0.15 0.14 0.14 0.16 0.15 0.19 0.18 MnO 0.35 0.37 0.37 0.34 0.31 0.44 0.39 CaO 0.02 0.02 0 0.02 0.03 0.01 0.14 Na20 0.01 0.02 0 0.02 0.02 0.01 0.03 K 20 0 0.02 0.02 0.02 0.01 0 0.01 F 0.13 0.12 0.3 0.29 0.07 0.7 0.58 CI 0.08 0.07 0.1 0.06 0.1 0.07 0.08 H 20 * 11.26 11.25 11.1 11.16 11.27 10.97 11.01 0=F -0.05 -0.05 -0.13 -0.12 -0.03 -0.29 -0.24 o=ci -0.02 -0.02 -0.02 -0.01 -0.02 -0.02 -0.02 TOTAL 99.53 99.5 98.83 99.11 99.74 99.7 99.56 Si 4 + , 5.31 5.44 5.44 5.33 5.31 5.38 5.24 Al 3 + 5.47 5.22 5.34 5.44 5.40 5.40 5.48 Ti 4 + 0.01 0.01 0.01 0.01 0.01 0.01 0.01 Fe2 + 4.75 4.78 4.75 4.67 4.83 4.86 4.78 Cr* 0.01 0.00 0.02 0.01 0.01 0.01 0.00 Mg2 + 4.30 4.39 4.22 4.38 4.35 4.14 4.36 Ni 2 + 0.03 0.02 0.02 0.03 0.03 0.03 0.03 Mn2 + 0.06 0.07 0.07 0.06 0.06 0.08 0.07 Ca 2 + 0.01 0.01 0.00 0.01 0.01 0.00 0.03 Na+ 0.00 0.01 0.00 0.01 0.01 0.00 0.01 K+ 0.00 0.01 0.01 0.01 0.00 0.00 0.00 F" 0.09 0.08 0.20 0.19 0.05 0.47 0.39 CI" 0.03 0.03 0.04 0.02 0.04 0.03 0.03 H + 15.88 15.89 15.76 15.78 15.92 15.51 15.58 o2- 35.88 35.89 35.76 35.78 35.92 35.51 35.58 cation sum 19.94 19.95 19.87 19.94 19.99 19.91 20.01 anion sum 36 36 36 36 36 36 36 MAIN TAILINGS 1. chamosite 2. chamosite 4. chamosite * Determined by stoichiometry 3. chamosite 5. chamosite H 20 calculated assuming 16 (OH" ,F" ,CL") 6. chamosite Based on36 anions. 7. chamosite Table 7.4: (Cont'd). TOTAL TAILINGS 1. 2. 3. 4. Si0 2 25.30 25.17 25.08 23.83 A l 2 0 3 21.15 20.54 21.21 20.51 T i 0 2 0.07 0.06 0.06 0.05 FeO 24.65 24.80 24.98 26.68 C r 2 0 3 0.11 0.10 0.03 0.11 MgO 15.71 15.54 15.18 14.52 NiO 0.10 0.17 0.11 0.11 MnO 0.24 0.21 0.23 0.27 CaO 0.02 0.01 0.01 0.04 Na 2 0 0.02 0.00 0.02 0.02 K 2 0 0.00 0.00 0.03 0.00 F 0.07 0.20 0.09 0.09 CI 0.04 0.08 0.12 0.08 H 2 0 * 11.31 11.11 11.20 10.94 0=F -0.03 -0.08 -0.04 -0.04 o=ci -0.01 -0.02 -0.03 -0.02 TOTAL 98.76 97.89 98.29 97.20 S i 4 + 5.34 5.38 5.34 5.19 A l 3 + 5.26 5.17 5.32 5.27 T i 4 + 0.01 0.01 0.01 0.01 Fe 2 + 4.35 4.43 4.44 4.86 C r * 0.02 0.02 0.01 0.02 M g * 4.95 4.95 4.81 4.72 N i * 0.02 0.03 0.02 0.02 M n * 0.04 0.04 0.04 0.05 C a * 0.01 0.00 0.00 0.01 Na+- 0.01 0.00 0.01 0.01 K+ 0.00 0.00 0.01 0.00 F" 0.05 0.14 0.06 0.06 c r 0.01 0.03 0.04 0.03 H + 15.94 15.84 15.90 15.91 o 2 - 35.94 35.84 35.90 35.91 cation sum 20.01 20.02 20.00 20.16 anion sum 36 36 36 36 TOTAL TAILINGS 1. ferroan clinochlore 2. ferroan clinochlore * Determined by stoichiometry 3. ferroan clinochlore H 2 0 calculated assuming 16 (OH" ,F" ,CL") 4. ferroan clinochlore Based on36 anions. Table 7.5: Electron probe microanalysis results for pyroxenes, with nomenclature based on criteria in Morimoto (1988). LOW SULFUR TAILINGS MAIN TAILINGS 1. 2. 1. 2. Si0 2 53.37 58.22 53.15 53.22 A l 2 0 3 0.85 1.10 2.08 2.09 T i 0 2 0.19 0.02 0.35 0.35 FeO 23.86 10.52 16.51 16.68 C r 2 0 3 0.09 0.00 0.08 0.08 MgO 20.95 16.69 26.44 26.27 MnO 0.38 0.78 0.32 0.29 CaO 1.56 11.67 1.24 1.11 Na 2 0 0.01 0.20 0.05 0.04 TOTAL 101.29 99.36 100.22 100.13 S i 4 + 1.98 2.11 1.93 1.93 A l 3 + 0.04 0.05 0.09 0.09 T i 4 + 0.01 0.00 0.01 0.01 Fe 2 + 0.74 0.32 0.50 0.51 C r * 0.00 0.00 0.00 0.00 Mg 2 + 1.16 0.90 1.43 1.42 Mn 2 + 0.01 0.02 0.01 0.01 C a 2 + 0.06 0.45 0.05 0.04 Na + 0.00 0.01 0.00 0.00 cation sum 4.00 3.87 4.02 4.02 anion sum 6 6 6 6 LOW SULFUR TAILINGS MAIN TAILINGS 1. enstatite 1. enstatite 2. augite 2. enstatite Based on 6 anions. Table 7.5: (Cont'd). TOTAL TAILINGS 1. 2. Si0 2 52.04 51.29 Al 2 0 3 4.14 5.21 Ti0 2 0.28 0.38 FeO 18.57 18.34 Cr 20 3 0.04 0.03 MgO 24.81 24.44 MnO 0.34 0.35 CaO 0.28 0.32 Na20 0.00 0.01 TOTAL 100.50 100.37 Si 4 + 1.89 1.87 Al 3 + 0.18 0.22 Ti 4 + 0.01 0.01 Fe2 + 0.57 0.56 Cr3* 0.00 0.00 Mg2 + 1.35 1.33 Mn2 + 0.01 0.01 Ca 2 + 0.01 0.01 Na+ 0.00 0.00 cation sum 4.01 4.01 anion sum 6 6 TOTAL TAILINGS 1. enstatite 2. enstatite Based on 6 anions. 94 Ca Fe Figure 7.1: Ca-Mg-Fe Ternary diagram for pyroxenes, and analyses from this study compared to those given in Scribbins et al, (1984); and Pattison. (1979). 7.1.2 Oxides The oxides in the tailings are magnetite and ilmenite in approximately equal proportions. Analyses of grains that exhibited no apparent intergrowths are given in tables 7.6 and 7.7. Fe 3 + and Fe 2 + were calculated by charge balance in all the oxide analyses. Magnetite compositions range from 0.05 to 6.72 wt % T i 0 2 , the latter possibly due to microscopic intergrowths of ilmenite. The average T i 0 2 content is 1.76 wt. %. C r 2 0 3 content averages 0.24 wt. %, and MnO was approximately 0.10 wt. %. Nickel is detected in most samples and averages 0.08 wt. % NiO. Some of the magnetite grains analyzed in this study contain considerable vanadium (as high as 0.85 wt. % V 2 0 3 ) . As these vanadium-rich grains are not significantly enriched in titanium interference of Table 7.6: Electron probe microanalysis results for magnetite. LOW SULFUR TAILINGS MAIN TAILINGS 1. 2. 3. 1. 2. 3. S I O 2 0.04 0.04 0.07 0.08 0.04 0.09 T I O 2 0.75 0.84 0.05 0.21 0.80 0.76 A L 2 0 3 0.01 0.07 0.00 0.36 1.14 0.99 C R 2 0 3 0.48 0.49 0.03 0.00 0.03 0.04 V 2 0 3 0.76 0.85 0.02 0.01 0.19 0.16 FE2O3 67.04 66.34 68.60 67.33 66.16 66.31 F E O 32.05 31.93 31.09 30.45 31.56 31.35 M G O 0.00 0.03 0.00 0.10 0.00 0.01 M N O 0.06 0.06 0.00 0.19 0.26 0.21 Z N O 0.00 0.00 0.00 0.00 0.40 0.57 C O O 0.00 0.06 0.00 0.00 0.00 0.00 N I O 0.06 0.03 0.02 0.19 0.04 0.10 C A O 0.03 0.01 0.03 0.09 0.00 0.02 N A 2 0 0.00 0.00 0.00 0.00 0.00 0.00 T O T A L 101.28 100.75 99.90 99.01 100.62 100.61 Sl 4 + 0.00 0.00 0.00 0.00 0.00 0.00 Tl 4 + 0.02 0.02 0.00 0.01 0.02 0.02 AL 3 + 0.00 0.00 0.00 0.02 0.05 0.04 CR 3 + 0.01 0.02 0.00 0.00 0.00 0.00 V 3 + 0.02 0.03 0.00 0.00 0.01 0.01 FE 3 + 1.92 1.91 1.99 1.97 1.89 1.90 FE 2 + 1.02 1.02 1.00 0.99 1.00 1.00 MG 2 + 0.00 0.00 0.00 0.01 0.00 0.00 MN 2 + 0.00 0.00 0.00 0.01 0.01 0.01 ZN 2 + 0.00 0.00 0.00 0.00 0.01 0.02 C0 2 + 0.00 0.00 0.00 0.00 0.00 0.00 Nl 2 + 0.00 0.00 0.00 0.01 0.00 0.00 CA 2 + 0.00 0.00 0.00 0.00 0.00 0.00 NA+ 0.00 0.00 0.00 0.00 0.00 0.00 CATION 3 3 .3 3 3 3 SUM O 4 4 4 4 4 4 Based on 4 oxygens. Table 7.6: (Cont'd). TOTAL TAILINGS 1. 2. 3. 4. 5. S I O 2 0.07 0.04 0.05 0.04 0.57 T I O 2 1.97 0.70 3.42 3.15 6.72 AL203 0.25 0.31 0.67 1.02 0.48 CR203 0.29 0.30 0.30 0.36 0.35 v 2 o 3 0.49 0.66 0.64 0.60 0.50 F E 2 0 3 63.66 66.29 59.95 59.81 52.97 F E O 32.64 31.65 33.93 33.51 37.08 M G O 0.00 0.00 0.03 0.00 0.25 M N O 0.04 0.00 0.10 0.04 0.27 Z N O 0.00 0.07 0.00 0.22 0.00 C O O 0.00 0.00 0.02 0.00 0.03 N I O 0.10 0.13 0.03 0.06 0.08 C A O 0.10 0.01 0.02 0.03 0.09 N A 2 0 0.00 0.00 0.00 0.00 0.00 T O T A L 99.61 100.16 99.17 98.84 99.39 S l 4 + 0.00 0.00 0.00 0.00 0.02 T l 4 + 0.06 0.02 0.10 0.09 0.19 A L 3 + 0.01 0.01 0.03 0.05 0.02 C R 3 + 0.01 0.01 0.01 0.01 0.01 V 3 + 0.02 0.02 0.02 0.02 0.02 F E 3 + 1.85 1.91 1.74 1.74 1.52 F E 2 + 1.05 1.02 1.09 1.08 1.19 M G 2 + 0.00 0.00 0.00 0.00 0.01 M N 2 + 0.00 0.00 0.00 0.00 0.01 Z N 2 + 0.00 0.00 0.00 0.01 0.00 c o 2 + 0.00 0.00 0.00 0.00 0.00 N l 2 + 0.00 0.00 0.00 0.00 0.00 C A 2 + 0.00 0.00 0.00 0.00 0.00 N A + 0.00 0.00 0.00 0.00 0.00 C A T I O N 3 3 3 3 3 S U M O 4 4 4 4 4 Based on 4 oxygens. Table 7.7: Electron probe microanalysis results for ilmenite. LOW SULFUR TAILINGS 1. 2. 3. 4. 5. S I O 2 0.00 0.05 0.03 0.01 0.02 T I O 2 52.30 51.80 51.12 52.16 52.52 AL203 0.01 0.00 0.06 0.03 0.01 C R 2 0 3 0.00 0.00 0.04 0.07 0.00 V 2 0 3 0.03 0.14 0.15 0.13 0.08 FE2O3 1.07 1.98 2.57 0.90 0.12 F E O 44.07 43.49 43.08 42.92 44.36 M G O 0.06 0.00 0.00 0.15 0.08 M N O 2.78 2.87 2.58 3.62 2.68 Z N O 0.00 0.10 0.08 0.04 0.00 C O O 0.00 0.00 0.00 0.00 0.00 N I O 0.02 0.00 0.00 0.00 0.00 C A O 0.01 0.12 0.19 0.02 0.03 N A 2 0 0.00 0.00 0.00 0.00 0.00 T O T A L 100.36 100.55 99.90 100.05 99.89 Sl 4 + 0.00 0.00 0.00 0.00 0.00 Tl 4 + 0.99 0.98 0.97 0.99 1.00 A L 3 * 0.00 0.00 0.00 0.00 0.00 C R 3 + 0.00 0.00 0.00 0.00 0.00 V 3 + 0.00 0.00 0.00 0.00 0.00 F E 3 + 0.02 0.04 0.05 0.02 0.00 F E 2 + 0.93 0.91 0.91 0.91 0.94 M G 2 + 0.00 0.00 0.00 0.01 0.00 M N 2 + 0.06 0.06 0.06 0.08 0.06 Z N 2 + 0.00 0.00 0.00 0.00 0.00 C0 2 + 0.00 0.00 0.00 0.00 0.00 Nl 2 + 0.00 0.00 0.00 0.00 0.00 C A 2 + 0.00 0.00 0.01 0.00 0.00 N A + 0.00 0.00 0.00 0.00 0.00 C A T I O N 2 2 2 2 2 S U M O 3 3 3 3 3 Based on 3 oxygens. 98 Table 7.7: (Cont'd). MAIN TAILINGS 1. 2. 3. 4. 5. 6. 7. S I O 2 0.01 0.05 0.01 0.01 0.06 0.00 0.03 T I O 2 52.67 52.34 51.99 53.10 52.64 52.71 52.07 AL203 0.01 0.02 0.00 0.01 0.00 0.02 0.00 C R 2 o 3 0.00 0.03 0.00 0.03 0.00 0.02 0.12 v 2 o 3 0.18 0.16 0.00 0.12 0.11 0.11 0.19 F E 2 0 3 0.00 1.73 1.41 0.00 0.00 0.51 1.55 F E O 44.83 44.65 44.37 45.12 43.28 44.82 44.26 M G O 0.03 0.24 0.22 0.13 0.19 0.98 0.91 M N O 2.12 1.78 1.82 1.93 2.86 0.79 0.78 Z N O 0.17 0.12 0.02 0.06 0.20 0.00 0.05 C O O 0.00 0.06 0.00 0.00 0.02 0.00 0.04 N I O 0.00 0.00 0.00 0.02 0.00 0.03 0.08 C A O 0.04 0.03 0.00 0.03 0.17 0.00 0.02 N A 2 0 0.00 0.01 0.03 0.01 0.02 0.00 0.00 T O T A L 100.06 101.21 99.87 100.57 99.55 99.99 100.11 S l 4 + 0.00 0.00 0.00 0.00 0.00 0.00 0.00 T l 4 + 1.00 0.98 0.99 1.00 1.00 0.99 0.98 A L 3 + 0.00 0.00 0.00 0.00 0.00 0.00 0.00 C R 3 + 0.00 0.00 0.00 0.00 0.00 0.00 0.00 V 3 + 0.00 0.00 0.00 0.00 0.00 0.00 0.00 F E 3 + 0.00 0.03 0.03 0.00 0.00 0.01 0.03 F E 2 + 0.95 0.93 0.94 0.95 0.92 0.94 0.93 M G 2 + 0.00 0.01 0.01 0.01 0.01 0.04 0.03 M N 2 + 0.05 0.04 0.04 0.04 0.06 0.02 0.02 Z N 2 + 0.00 • 0.00 0.00 0.00 0.00 0.00 0.00 c o 2 + 0.00 0.00 0.00 0.00 0.00 0.00 0.00 N l 2 + 0.00 0.00 0.00 0.00 0.00 0.00 0.00 C A 2 + 0.00 0.00 0.00 0.00 0.01 0.00 0.00 N A + 0.00 0.00 0.00 0.00 0.00 0.00 0.00 C A T I O N 2 2 2 2 2 2 2 S U M O 3 3 3 3 3 3 3 Based on 3 oxygens. 99 Table 7.7: (cont'd). TOTAL TAILINGS 1. 2. 3. 4. 5. 6. 7. S I O 2 1.64 0.04 0.03 0.05 0.05 0.07 0.03 T I O 2 48.86 51.44 51.32 51.78 50.21 51.79 52.34 AL203 1.51 0.01 0.00 0.00 0.02 0.01 0.01 C R 2 o 3 0.00 0.00 0.02 0.07 0.02 0.00 0.00 v 2 o 3 0.18 0.07 0.13 0.12 0.11 0.19 0.18 FE203 3.16 1.13 1.34 0.38 3.02 0.61 0.00 F E O 40.77 43.24 43.33 44.50 43.28 43.73 44.19 M G O 1.50 0.13 0.15 0.15 0.33 0.21 0.18 M N O 2.22 2.35 2.25 1.56 1.08 2.27 2.35 Z N O 0.00 0.21 0.00 0.00 0.00 0.00 0.01 C O O 0.00 0.01 0.03 0.01 0.00 0.03 0.00 N I O 0.00 0.01 0.01 0.08 0.00 0.07 0.00 C A O 0.16 0.19 0.21 0.15 0.16 0.12 0.11 NA 20 0.00 0.00 0.00 0.00 0.01 0.00 0.00 T O T A L 100.00 98.83 98.82 98.85 98.28 99.10 99.40 Sl 4 + 0.04 0.00 0.00 0.00 0.00 0.00 0.00 Tl 4 + 0.91 0.99 0.99 0.99 0.97 0.99 1.00 AL 3 + 0.04 0.00 0.00 0.00 0.00 0.00 0.00 C R 3 + 0.00 0.00 0.00 0.00 0.00 0.00 0.00 V 3 + 0.00 0.00 0.00 0.00 0.00 0.00 0.00 F E 3 + 0.06 0.02 0.03 0.01 0.06 0.01 0.00 F E 2 + 0.84 0.92 0.93 0.95 0.93 0.93 0.94 M G 2 + 0.06 0.01 0.01 0.01 0.01 0.01 0.01 M N 2 + 0.05 0.05 0.05 0.03 0.02 0.05 0.05 Z N 2 + 0.00 0.00 0.00 0.00 0.00 0.00 0.00 c o 2 + 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Nl 2 + 0.00 0.00 0.00 0.00 0.00 0.00 0.00 C A 2 + 0.00 0.01 0.01 0.00 0.00 0.00 0.00 NA+ 0.00 0.00 0.00 0.00 0.00 0.00 0.00 C A T I O N 2 2 2 2 2 2 2 S U M O 3 3 3 3 3 3 3 Based on 3 oxygens. 100 the V K a line by Ti Kp radiation can be discredited. Vanadium in magnetite has also been reported in the Sudbury region by Hawley (1962). Ilmenite in the tailings averages 0.08 wt. % Cr 20 3, 0.13 wt. % V 2 0 3 , and 2.14 wt. % MnO. These results are similar to those reported for magnetite and ilmenite in the South Range of the Sudbury igneous complex (Gasparrini andNaldrett, 1972). 7.1.3 Sulfide Pyrrhotite with an iron content greater than Fe 7S s has a low-magnetic susceptibility and is hexagonal in symmetry, whereas pyrrhotite with an Fe:S less than Fe 7S 8 is highly-magnetic and monoclinic, both varieties have been reported in the Sudbury igneous complex (Michener and Yates, 1944; Cowan, 1968). Cowan noted that the distribution of hexagonal versus monoclinic pyrrhotite has no direct correlation with the nickel concentration in the iron-nickel sulfides, and discrete grains or aggregates of pentlandite are associated with both hexagonal and monoclinic pyrrhotite, but exsolution lamellae of pentlandite most commonly occur in the monoclinic variety. According to Hawley (1962) the nickel content in pyrrhotite ranges from 0.58 wt. % to 1.61 wt. % and cobalt from 0.023 wt. % to 0.060 wt. %. Dickson (1904) reported that lead, selenium, chromium, vanadium and titanium have also been detected in Sudbury pyrrhotite; however, he attributed the Ni and Co to finely intergrown pentlandite, the lead to inclusions of galena, chromium, vanadium, and titanium to minute inclusions of silicates and oxides, and selenium to be substituting for sulfur in the pyrrhotite structure. The electron microprobe analyses done in this study showed pyrrhotite compositions to also vary both above and below the Fe 7S 8 formula from (Fe7.34,Ni0.07)s;=7.4iS8 to (Fe^NiaoeWssSs. Table 7.8 gives the results of the electron probe analyses for pyrrhotite analyzed in this study compared to analyses from 101 CO > * £ II E O P "O CD CD ~ 2 o € E o. 3 O O) 10 = 3 3 w ^ 2 .1 w or CD o TO Z S o> o -i= E E CD O c o o .e o CD Q . UJ O •o CD 00 ^ CD CD C L £3 CD H E o o CO O < CD c CO o CD CD CD C CD LU o CD > CD CD CO (3 " j ° CD < a) 2r h- CD CD CZ CD < o CD > CD CO CO Z o co CD CD <f> cn >> < 2 CD CD C > ro CD C O CO o z < CD c CD LL _l (0 o C D co C D O J CO C D C D d ° . ^ co o i -• i i m m o m o o C D o CO C M C N CO d • m d 0 C D i o> m 01 CNJ C N m T -d d • i i n C N d o o o> co - o o <2 o o o ' m o o o T - T I - C D O C N O O O O C O O O p O O p d d d d d d d d m T— o> m oi d o o CO C D d d d d d C D d d CO o o d o> d d d O J C O O T - O ^ O C O O T J - O O T - O O O O . O ^ I - O O O O O O g o o d g o o o o o o o o o> C O d CO I i n C D oi O ) d co o> oo d i n • o C D C D d I C D d o o o o o o o d d o oo o d d T - CO o o o o o o o o q o ' d d c6 d d CO i _ C CD O . _ O «E LL O Z 3 C (/> T3 . Q . Q O N < O W 0. o o o o m d o m C N d o < I— O o o r- C N oo o T - o o o o o o o o o o oo o d d o C D C N o oo o T - d d CO O I— < D O CD LL CO LL 102 the Nickel Rim tailings, (Jambor and Owens, 1993). The nickel and cobalt concentrations in the pyrrhotite from the Nickel Rim tailings are greater than in the Copper Cliff tailings, and is interpreted to be a result of pentlandite intergrowths in the pyrrhotite. The formula for the pentlandite found in the Sudbury area is best expressed as (Ni, Co) 4 .7 5 Fe4 2 5 S8. according to Hawley (1962) and references therein. He reports that the atomic ratio of (Ni+Co)/Fe averages 1.11, the Ni/Co ratio (by weight) for most pentlandites is 34:1, and the percentage of cobalt varies between 0.115 and 1.36 wt. %. Silver, bismuth, lead and selenium were also reported by Hawley to occur in pentlandite from various locations in the Sudbury region. Pentlandite compositions in the Clarabelle tailings range between (Ni478,Fe4.3iCoo.os)5;=9 nS 8 and (Ni4.34,Fe4.34Coo.i5)i=8s3S8. The (Ni+Co)/Fe ratio averages 1.12, closely corresponding to that referenced above, and the cobalt varies between 0.84 and 1.76 wt. %, higher than in pentlandite from the Nickel Rim tailings (table 7.9). Minor amounts of chromium and cadmium were also detected in a few grains 7.2 Quantitative Analysis and Imaging of Altered Minerals 7.2.1 Silicates The only silicate that has altered significantly as a result of its presence in the tailings environment is biotite. Products of biotite oxidation, such as vermiculite and cristobalite, have been noted in studies of oxidized tailings (Jambor, 1994), and similar results were obtained here. The alteration was detected in the total tailings in both the lysimeter and the oxidation column. The alteration was distinguished in thin section by a bleached colour and weaker pleochroism compared to unoxidized biotite, as was discussed in section 5.2.2. The alteration is distinguished initially by a decrease in potassium, which is followed by iron 103 CO O z < LU o (0 o to 'to _>«! ro _>>| ro c CO (0 O z z < CP 0)i o "> 03 (/) O) 2 CO > ro ro oo (0 o z CD O) tz ro 0£ LL _l W 5 o O CD -I1 CO CO l- c CO CO ro CNJ I O LU O OO C\i oo o CD : I CM co o o 8 o ~ o o o co CO co CN T - -r- o o o o o o o o o o o b b ^ - r ^ ^ o o o o o o oo co co CO o co in CO O O CM oo CN co o o o ~ o o 6 ^ CO O T- CN i- O O o o o o o o o o o o b o co CO CO CO o r~- T - CD co b co co b co CO co CO o o o o o o o CD CD CN CO C D m CO CO T - 1 - CD CN O o o o o o d d d d d CO c3l CD O u. O z ^ C 10 T3 . Q .£3 O N < O CO 0. o CN b o co b o CN CN cn cn co CD b o < t- O o r-~ o T - o> o oo o o oo CD i n o o to T - od b O CD 00 CD O T- in -r- oo -<t b o oo m O i f ) CO r- CO i f c i CO g I— < on => Oi O Ll_ CO CD o o 104 and magnesium depletion and a subsequent increase in silica until an end product similar to cristobalite is achieved. The formulas for the altered biotite grains, calculated from electron microprobe data on the basis of 3 Si cations, are given in table 7.10. Debye-Scherrer x-ray diffraction results on a strongly altered biotite from the total tailings column gave two lines, the strongest line at 4.07 A, which closely matches that for cristobalite (4.04 A), and a second, broader line at 3.68 A. F O R M U L A ideal formula K(Mg,Fe 2 +) 3(Al,Fe 3 +)Si3O 1 0(OH,F) T O T A L T A I L I N G S F I E L D L Y S I M E T E R weakly altered area; grain # 1 Kfj.83(Fei.31 Mg) 2s) E=2.59(A11 57Tin. 11 )Si3.oo strongly altered area; grain #1 Ko.iefFei.ogMgi.os) s=ii4(Al1.32Tio.ii)Si3.oo T O T A L T A I L I N G S O X I D A T I O N C O L U M N weakly altered area , grain #2 Ko.35(Feo.79Mgo.6l) 2>1.4o(Alo.86Tio.Os)Si3.00 strongly altered area, grain #2 Ko.os(Feo.35Mgo.i5) î .5o(Alo.26Tio.o4)Si3.oo strongly altered grain #3 Ko.i2(Feo.4oMg0.3o) i=o.7o(Alo.35Tio.oi)Si3.oo strongly altered grain #4 Ko.07(Feo.4oMgo. 12) S=0.52(Alo.27Tio.05)Si3.00 Table 7.10: Approximate formula of altered biotite in the total tailings field lysimeter and oxidation column (calculated from electron microprobe analysis results). The degree of alteration is variable within each grain, as is evident optically and is documented by BSE images and multi-element x-ray maps. Figure 7.2a (grain #1 in table 7.10) shows the BSE image and corresponding points of analysis of an altered biotite from the total tailings lysimeter pit. The more strongly altered areas in the grain are darker grey than those less altered, and the separation along the basal cleavage is greatest where the alteration is the most intense. Multi-element x-ray maps for Al , Fe, K, Mg, © © © © © © © © © ® Si02 33.81 38.90 36.69 34.13 36.81 29.02 44.51 34.57 38.36 37.61 AI203 15.13 14.47 13.84 15.02 15.83 12.25 13.07 16.07 13.70 15.30 Ti02 1.91 1.87 1.73 1.57 1.67 1.40 1.64 1.64 1.78 1.90 FeO 17.38 17.16 16.91 16.99 18.88 13.15 15.20 19.36 16.62 17.67 Cr203 0.06 0.07 0.01 0.03 0.00 0.01 0.04 0.01 0.02 0.03 MgO 9.60 9.19 9.02 9.56 10.10 7.44 8.21 10.52 8.48 9.98 NiO 0.12 0.07 0.16 0.08 0.10 0.16 0.08 0.08 0.14 0.12 MnO 0.09 0.06 0.11 0.12 0.12 0.07 009 0.10 0.08 0.06 CaO 0.94 0.97 0.75 0.33 0.18 0.64 0.75 0.14 0.69 0.82 Na20 1.27 1.22 1.04 0.32 0.31 0.75 0.90 0.19 1.04 1.29 K20 1.30 1.15 1.58 6.48 8.08 1.39 1.32 8.48 2.43 1.70 F 1.45 1.38 1.22 0.98 0.89 0.97 1 34 0.64 1.15 1.26 CI 0.48 0.50 0.61 0.59 0.66 0.61 0.56 0.60 0.68 0.51 H20 * 2.99 2.96 2.84 2.95 3.25 2.28 3.10 3.30 2.93 3.04 O F -0.61 -0.58 -0.51 -0.41 -0.37 -0.41 -0.56 -0.27 -0.48 -0.53 0=CI -0.11 -0.11 -0.14 -0.13 -0.15 -0.14 -0.13 -0.14 -0.15 -0.12 TOTAL 90.81 89.28 85.86 88.60 96.35 69.60 90.12 95.30 87.46 90.64 Si4+ 6.13 6.23 6.16 5.75 5.75 6.00 6.88 5.52 6.31 5.99 AI3+ 2.81 2.73 2.74 2.98 2.92 2.99 2.38 3.02 2.66 2.87 Ti4+ 0.23 0.23 0.22 0.20 0.20 0.22 0.19 0.20 0.22 0.23 FeT 2.29 2.30 2.37 2.39 2.47 2.27 1.97 2.59 2.29 2.35 Cr3+ 0.01 0.01 0.00 0.00 0.00 0.00 0.01 0.00 0.00 0.00 Mg2+ 2.26 2.19 2.26 2.40 2 35 2.29 1.89 2.50 2.08 2.37 Ni2+ 0.02 0.01 0.02 0.01 0.01 0.03 0.01 0.01 0.02 0.02 Mn2+ 0 01 0.01 0.02 0.02 0.02 0.01 0.01 0.01 0.01 0.01 Ca2+ 0.16 0.17 0.14 0.06 0.03 0.14 0.12 0.02 0.12 0.14 Na+ 0.39 0.38 0.34 0.10 0.09 0.30 0.27 0.06 0.33 0.40 K+ 0.26 0.24 0.34 1.39 1.61 0.37 0.26 1.73 0.51 0.35 F- 0.72 0.70 0.65 0.52 0.44 0.63 0.66 0.32 0.60 0.63 Cl- 0.13 0.14 0.17 0.17 0.18 0.21 0.15 0.16 0.19 0.14 H+ 3.15 3.17 3.18 3.31 3.39 3.15 3.20 3.51 3.21 3.23 02- 23.15 23.17 23.18 23.31 23.39 23.15 23.20 23.51 23.21 23.23 cation sum 14.56 14.48 14.59 15.31 15.45 14.62 14.00 15.66 14.56 14.72 anion sum 24 24 24 24 24 24 24 24 24 24 * H20 determined by stoichiometry. Based on 24 anions. Figure 7.2a: BSE image and corresponding EPMA results of altered biotite grain from the total tailings lysimeter. Scale bar equals 100 micrometres. Figure 7.2b: Mulit-element x-ray maps of altered mica from the total tailings lysimeter; Scale bar equals 100 micrometres 107 and Si for the same grain are given in figure 7.2b. Potassium shows the most distinct depletion in the altered region. A similar grain from the total tailings oxidation column is shown in figures 7.3a and 7.3b. The more intensely oxidized areas in this grain are also darker grey in the BSE image, and colourless in transmitted light. The E P M A results and the multi-element x-ray maps both show the depletion of Al , Fe, K, and Mg in this area. Points numbered 4 and 5 most closely represent residual mica. Figure 7.4 is the photomicrograph, BSE image and corresponding EPMA results for the altered biotite grain marked #3 in table 7.10. The grain, which is from the total tailings column, is more evenly altered and nearly completely colourless in transmitted light 7.2.2 Sulfides Considering that the silicates in the tailings were relatively inert and there were no carbonates detected, the principal focus of this thesis was recognized early as the documentation of oxidized sulfides, specifically pyrrhotite, pentlandite and chalcopyrite. The following section discusses the results of extensive imaging and electron probe microanalysis of altered pyrrhotite, pentlandite, chalcopyrite, and mixtures thereof, and has been divided into sections based on the different tailings types and the different experimental regimes to facilitate comparative conclusions. Low sulfur tailings lysimeter Oxidation of pyrrhotite in the low sulfur tailings lysimeter has occurred primarily along the parting plane and to a lesser extent around the grain edges. Two examples of this type of alteration were chosen from the unsaturated zone of the lysimeter. The backscattered electron (BSE) image and electron © (D <D ® (?) (D (?) Si02 57.83 63.64 62.10 48.03 48.53 63.71 63.99 AI203 3.34 5.41 5.03 11.98 11.43 4.71 4.26 Ti02 0.81 1.17 1.23 1.76 1.57 1.13 1.12 FeO 6.61 9.31 10.53 1578 14.73 8.76 8.41 Cr203 0.04 0.08 0.05 0.11 0.09 0.07 0.05 MgO 1.38 2.65 2.62 6.71 6.46 2.19 1.87 NiO 0.03 0.02 0.02 0.13 0.12 0.03 0.02 MnO 0.04 0.00 0.04 0.05 0.05 0.02 0.04 CaO 0.28 0.38 028 0.22 0.40 0.43 0.31 Na20 0.57 0.59 0.67 0.39 0.52 0.79 0.52 K20 0.63 1.61 1.43 4.84 4.10 1.53 1.08 F 0.52 0.49 0.45 0.32 0.65 0.52 0.31 Cl 0.66 0.65 0.76 0.65 0.69 0.90 0.71 H20 * 3.18 3.76 3.67 3.69 3.48 3.62 3.72 O F -0.22 -0.21 -0.19 -0.13 -0.27 -0.22 -0.13 0=CI -0.15 -0.15 -0.17 -0.15 -0.16 -0.20 -0.16 TOTAL 75.55 8941 88.52 94.38 92.39 87.99 86.12 Si4+ 9.66 9.18 9.13 7.19 734 932 9.47 AI3+ 0.66 0.92 0.87 2.11 2.04 0.81 0.74 Ti4+ 0.10 0.13 0.14 0.20 0.18 0.12 0.13 FeT 0.92 1.12 1.30 1.97 1.86 1.07 1.04 Cr3+ 0.01 0.01 0.01 0.01 0.01 0.01 0.01 Mg2+ 0.34 0.57 0.57 1.50 1 46 0.48 0.41 Ni2+ 0.00 0.00 0.00 0.02 0.02 0.00 0.00 Mn2+ 0.01 0.00 0.01 0.01 0.01 0.00 0.01 Ca2+ 0.05 0.06 0.04 0.04 0.07 0.07 0.05 Na+ 0.19 0.17 0.19 0.11 0.15 0.22 0.15 K+ 0.13 0.30 0.27 0.92 0.79 0.29 0.20 F- 0.28 0.22 0.21 0.15 0.31 0.24 0.15 Cl- 0.19 0.16 0.19 0.17 0.18 0.22 0.18 H+ 3.54 3.62 3.60 3.68 3.51 3.54 3.68 02- 23.54 23.62 23.60 23 68 23.51 23.54 23.68 cation sum 12.07 12.46 12.52 14.07 13.92 12.40 12.21 anion sum 24 24 24 24 24 24 24 * H 2 0 determined by stoichiometry. Based on 24 anions. Figure 7.3a: B S E image, photomicrograph, and corresponding E P M A results of altered biotite grain from the total tailings oxidation column. Scale bar equals 50 micrometres. Figure 7.3b: Multi-element x-ray maps of altered biotite from the total tailings column; Scale bar equals 50 micrometres. 110 Si02 6256 61.88 59.48 56.55 2824 AI203 4.14 4.18 4.00 6.14 2.24 Ti02 1.33 1.41 1.17 1.59 0.58 FeO 9.10 9.43 825 11.66 4.27 Cr203 002 0.04 0.06 0.05 0.02 MgO 1 31 1.41 1.43 2.46 0.73 NiO 0.04 0.01 0.07 0.07 0.05 MnO 0.03 0.05 0.00 0.05 0.01 CaO 038 0.34 0.54 0.40 0.18 Na20 062 0.54 0.64 0.68 0.19 K20 0.76 0 86 1.06 1.77 0.41 F 053 0.85 0.68 0.75 0.58 CI 0.54 0.43 0.53 0.53 0.35 H20 * 3.58 3.43 3.33 3.38 1.45 0=F -0.22 -0.36 -0.29 -0.32 -024 0=CI -0.12 -0.10 -0.12 -0.12 -0.08 TOTAL 84 59 8441 80.83 8565 38 98 Si4+ 945 9.40 9.43 8.75 9.32 AI3+ 074 0.75 0.75 112 0.87 Ti4+ 0.15 0.16 0.14 0.19 0.14 FeT 1.15 1.20 1.09 1.51 1.18 Cr3+ 0.00 0.01 0.01 0.01 0.01 Mg2+ 0.30 0.32 0.34 0.57 0.36 Ni2+ 0.01 0.00 0.01 0.01 0.01 Mn2+ 0.00 0.01 0.00 0.01 0.00 Ca2+ 0.06 0.06 0.09 0.07 0.06 Na+ 0.18 016 0.20 0.20 0.12 K+ 0.15 0.17 0.21 0.35 0.17 F- 0.25 0.41 0.34 0.37 0.61 Cl- 0.14 0.11 0.14 0.14 0.20 H+ 3.61 3.48 3.52 3.49 3.20 02- 23.61 23.48 23.52 23.49 23.20 cation sum 12.19 12.22 12.26 12.78 12.25 anion sum 24 24 24 24 24 *H20 determined by stoichiometry. Based on 24 anions. Figure 7.4: B S E image, photomicrograph, and corresponding E P M A results of altered biotite grain from the total tailings oxidation column. Scale bar equals 50 micrometres. microprobe analyses (EPMA) are given in figure 7.5a, and die corresponding multi-element x-ray maps are in figure 7.5b. The EPMA results of the oxidation products show a decrease in the nickel content and an elevated copper content relative to the primary pyrrhotite. The multi-element x-ray maps suggest that the oxidation phase is a nickel-poor iron oxyhydroxide with minor admixed sulfur, probably as sulfate. Multi-element x-ray maps for the second grain selected from this lysimeter closely resemble those described above for the first (figure 7.6). Pyrrhotite has altered to an iron oxyhydroxide containing remnant sulfur and less nickel than in the original grain. Electron probe microanalysis was not done on this grain. Pentlandite oxidation such as that seen in figures 7.7a and 7.7b was also found in the unsaturated zone of the low sulfur tailings lysimeter. The oxidation has resulted in at least 3 secondary phases. The thin rim directly adjacent to the existing pentlandite appears slightly depleted in iron and nickel relative to pentlandite which is illustrated best on the x-ray maps. The rim immediately surrounding the depleted edge is a nickeliferous iron oxyhydroxide. The third phase is a mixture of two or more phases, the bulk composition of which is higher in nickel, slightly higher in sulfur, and lower with respect to iron content than the iron oxyhydroxide. Cobalt, present in the pentlandite, is not retained in the secondary phases. Main tailings lysimeter Oxidation of pyrrhotite in the main tailings lysimeter occurred along the mineral's parting plane, along fractures in grains, and around the grain's edge as seen in the low sulfur tailings. Figures 7.8a and 7.8b show a nickeliferous pyrrhotite grain, from the unsaturated zone of the tailings that has altered to an iron oxyhydroxide. As was seen for the pyrrhotite alteration in the low sulfur tailings, the iron oxyhydroxide is lower in nickel than the primary pyrrhotite. wt.% (13 t2J S 39.89 39.65 Ti 0.00 0.00 Cr 0.00 0.01 Mn 0.02 0.00 Fe 59.53 59.40 Co 0.00 0.00 Ni 0.99 0.94 Cu 0.04 0.00 Zn 0.01 0.05 As 0.00 0.00 Cd 0.00 0.00 Sb 0.01 0.00 Pb 0.00 0.00 Atomic proportion S 1.24 1.24 Ti 0.00 0.00 Cr 0.00 0.00 Mn 0.00 0.00 Fe 1.07 1.06 Co 0.00 0.00 Ni 0.02 0.02 Cu 0.00 0.00 Zn 0.00 0.00 As 0.00 0.00 Cd 0.00 0.00 Sb 0.00 0.00 Pb 0.00 0.00 CD CD CD 39.82 1.74 1.15 8.98 0.01 0.01 0.01 0.00 0.00 0.00 0.01 0.00 0.00 0.00 0.00 0.02 59.89 48.04 17.38 47.53 0.00 0.02 0.02 0.00 0.49 0.13 0.09 0.20 0.00 0.29 0.11 0.10 0.04 0.03 0.02 0.00 0.00 0.00 0.01 0.00 0.02 0.02 0.02 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 1.24 0.05 0.04 0.28 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 1.07 0.86 0.31 0.85 0.00 0.00 0.00 0.00 0.01 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 C D C D C D 26.61 10.52 10.09 0.81 0.01 0.00 0.00 0.00 0.00 0.02 0.00 0.00 0.01 0.00 0.00 0.01 52.67 44.95 44.62 20.18 0.01 0.00 0.00 0.00 0.65 0.24 0.22 0.10 0.02 0.08 0.10 0.18 0.00 0.01 0.02 0.01 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.01 0.02 0.00 0.00 0.00 0.03 0.83 0.33 0.31 0.03 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.94 0.80 0.80 0.36 0.00 0.00 0.00 0.00 0.01 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Figure 7.5a: B S E image and E P M A results for altered pyrrhotite in low sulfur tailings lysimeter (5 cm depth). Scale bar equals 100 microns. Figure 7.5b: Multi-element x-ray maps and BSE image of altered pyrrhotite in the low sulfur tailings lysimeter; the box outlines the area seen in x-ray maps and in the enlargement of the BSE image. Scale bar equals 100 micrometres. Figure 7.6: Multi-element x-ray maps and BSE image of altered pyrrhotite from the low sulfur tailings lysimeter. Scale bar equals 50 micrometres. wt.% (1J (2) (3) S 33.12 33.47 33.70 Ti 0.00 0.01 0.03 Cr 0.00 0.00 0.02 Mn 0.00 0.00 0.00 Fe 33.10 32.88 31.94 Co 0.97 1.00 0.99 Ni 33.71 33.40 33.18 Cu 0.03 0.00 0.05 Zn 0.01 0.00 0.03 As 0.00 0.02 0.00 Cd 0.05 0.06 0.05 Sb 0.04 0.00 0.05 Pb 0.00 0.00 0.00 Atomic proportion S 1.03 1.04 1.05 Ti 0.00 0.00 0.00 Cr 0.00 0.00 0.00 Mn 0.00 0.00 0.00 Fe 0.59 0.59 0.57 Co 0.02 0.02 0.02 Ni 0.57 0.57 0.57 Cu 0.00 0.00 0.00 Zn 0.00 0.00 0.00 As 0.00 0.00 0.00 Cd 0.00 0.00 0.00 Sb 0.00 0.00 0.00 Pb 0.00 0.00 0.00 © © © ® © 0.43 0.42 1.20 3.74 3.24 0.00 0.01 0.01 0.01 0.01 0.00 0.00 0.01 0.01 0.00 0.03 0.01 0.01 0.08 0.11 47.29 47.77 47.78 24.67 26.40 0.01 0.00 0.00 0.02 0.01 3.55 3.57 4.00 11.85 12.48 0.01 0.00 0.00 0.17 0.22 0.02 0.00 0.01 0.01 0.00 0.00 0.04 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.06 0.00 0.02 0.03 0.02 0.02 0.00 0.04 0.00 0.00 0.00 0.01 0.01 0.04 0.12 0.10 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.85 0.86 0.86 0 44 0.47 0.00 0.00 0.00 0.00 0.00 0.06 0.06 0.07 0.20 0.21 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Figure 7.7a: B S E image and E P M A results of an altered pentlandite in low sulfur tailings lysimeter (35 cm depth). Scale bar equals 20 micrometres. Figure 7.7b: Multi-element x-ray maps of altered pentlandite from the low sulfur tailings lysimeter. Scale bar equals 20 micrometres. Figure 7.8a: B S E image and corresponding E P M A results of an altered pyrrhotite in main tailings lysimeter (5 cm depth). Scale bar equals 50 micrometres. Figure 7.8b: Multi-element x-ray maps for altered pyrrhotite from the main tailings lysimeter. Scale bar equals 50 micrometres. 119 A more strongly oxidized example can be seen in figures 7.9a and 7.9b. In this case, a pyrrhotite grain, averaging 0.74 wt. % Ni, has been replaced by an iron oxyhydroxide in which nickel content ranges from 0.03 to 0.41 wt. %. Residual sulfur, presumably as sulfate, that was retained in the iron oxyhydroxide can be seen predominantly where the surface is more uniform. The pyrrhotite grain in figures 7.10a and 7.10b shows fracture-controlled alteration that permeates outward from the core. The secondary' phase in the core of the grain is predominantly native sulfur with admixed iron oxyhydroxide. Covellite is present in a fracture near the top of the image and accounts for the high copper content in the EPMA result for analysis point number 10. Alteration has also occurred via iron oxyhydroxide replacement along fractures in the grain and as a thin, discontinuous rim. Debye- Scherrer x-ray diffraction results of this grain identified the iron oxyhydroxide as goethite. As opposed to the grains illustrated above, the example in figures 7.1 la and 7.1 lb is from the saturated zone of the lysimeter (90 cm from the surface). The pyrrhotite is rimmed by two phases, an inner, discontinuous nickel sulfide that contains approximately 0.18 wt. % Cu, and an outer colloform iron oxyhydroxide. In contrast to the relationships fro nickel in pyrrhotite and iron oxyhydroxide from the unsaturated zone, the nickel content in this example is greater in the iron oxyhydroxide than in the pyrrhotite. The iron oxyhydroxide is interpreted to have precipitated from solution, as indicated by the colloform texture, by the sharp contacts where it is directly adjacent to the pyrrhotite, and its location in the saturated zone. The analyses numbered 4 and 5 (figure 7.1 la) represent a mixture of pyrrhotite and a thin nickel sulfide rim that is easily differentiated on the nickel x-ray map. Alteration of pentlandite is also apparent in grains in the main tailings lysimeter. Figures 7.12a and 7.12b show a well developed oxidation rim on a penlandite grain from the unsaturated zone of the tailings. The rim is a mixture of two or more phases as indicated by the difference in grey scales on the Figure 7.9a: B S E image and corresponding E P M A results of altered pyrrhotite in the main tailings lysimeter (7.5 cm depth). Scale bar equals 50 micrometres. Figure 7.9b: Multi-element x-ray maps of altered pyrrhotite from the main tailings lysimeter. Scale bar equals 50 micrometres. Figure 7.10a: B S E image and corresoponding E P M A results of altered pyrrhotite in the main tailings lysimeter (15 cm depth). Scale bar equals 50 micrometres. Figure 7.10b: Multi-element x-ray maps and BSE image of altered pyrrhotite from the main tailings lysimeter. Scale bar equals 50 micrometres. wt.% © ® © © © ® © © © ® s 39.61 39.88 39.56 34.03 39.42 0.44 0.55 0.47 0.56 0.43 Ti 0.02 0.00 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 Cr 0.01 0.00 0.00 0.00 0.00 0.00 0.01 0.00 0.00 0.00 Mn 0.00 0.00 0.00 0.00 0.01 0.03 0.04 0.03 0.05 0.05 Fe 60.21 60.36 59.69 25.46 20.61 46.10 49.48 46.92 46.55 47.59 Co 0.00 0.00 0.00 0.02 0.07 0.00 0.01 0.00 0.01 0.00 Ni 0.40 0.36 0.58 20.05 24.05 1.48 1.41 1.70 1.66 1.64 Cu 0.00 0.00 0.03 0.17 0.18 0.00 0.01 0.01 0.02 0.02 Zn 0.00 0.00 0.00 0.01 0.00 0.05 0.02 0.06 0.08 0.04 As 0.03 0.01 0.00 0.00 0.04 0.00 0.00 0.00 0.00 0.00 Cd 0.00 0.00 0.00 0.06 0.00 0.00 0.00 0.00 0.02 0.00 Sb 0.00 0.00 0.00 0.00 0.05 0.01 0.01 0.02 0.00 0.00 Pb 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Atomic proportion S 1.24 1.24 1.23 1.06 1.23 0.01 0.02 0.01 0.02 0.01 Ti 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Cr 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Mn 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Fe 1.08 1.08 1.07 0.46 0.37 0.83 0.89 0.84 0.83 0.85 Co 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Ni 0.01 0.01 0.01 0.34 0.41 0.03 0.02 0.03 0.03 0.03 Cu 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Zn 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 As 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Cd 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Sb 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Pb 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Figure 7.11a: B S E image and corresponding E P M A results of altered pyrrhotite from the main tailings lysimeter (90 cm depth). Scale bar equals 50 micrometres. Figure 7.11b: Multi-element x-ray maps of altered pyrrhotite from the main tailings lysimeter. Scale bar equals 50 micrometres. wt.% (1J (2) S 33.27 33.27 Ti 0.00 0.00 Cr 0.00 0.00 Mn 0.00 0.00 Fe 30.86 30.87 Co 1.09 1.12 Ni 35.04 35.14 Cu 0.00 0.00 Zn 0.02 0.00 As 0.02 0.02 Cd 0.00 0.00 Sb 0.00 0.00 Pb 0.00 0.00 26.17 0.00 0.00 0.00 32.36 0.95 18.21 0.17 0.00 0.00 0.06 0.01 0.00 40.84 0.00 0.00 0.00 29.91 1.24 22.89 0.00 0.00 0.00 0.01 0.00 0.00 © (7 j 3167 26'60 22.17 0.00 0.00 0.00 0.00 0.00 0.01 0.01 0.00 0.03 32.24 34.08 33.94 1.13 0.99 0.88 21.27 18.08 17.20 0.06 0.22 0.17 0.00 0.02 0.01 0.00 0.00 0.00 0.00 0.00 0.01 0.00 0.02 0.00 0.00 0.00 0.00 © (9J (10) 29.07 1679 15.13 0.00 0.00 0.08 0.00 0.01 0.01 0.02 0.11 0.01 32.44 41.26 45.43 1.03 1.14 0.01 20.42 15.71 0.81 0.14 0.41 1.38 0.02 0.03 0.06 0.00 0.01 0.00 0.01 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Atomic proportion s 1.04 1.04 0.82 1.27 0.99 0.83 0.69 0.91 0.49 0.47 Ti 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Cr 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Mn 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Fe 0.55 0.55 0.58 0.54 0.58 0.61 0.61 0.58 0.74 0.81 Co 0.02 0.02 0.02 0.02 0.02 0.02 0.01 0.02 0.02 0.00 Ni 0.60 0.60 0.31 0.39 0.36 0.31 0.29 0.35 0.27 0.01 Cu 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.01 0.02 Zn 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 As 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Cd 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Sb 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Pb 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Figure 7.12a: B S E image and corresponding E P M A results of altered pentlandite from the main tailings lysimeter (15 cm depth). Scale bar equals 20 micrometres. Figure 7.12b: Multi-element x-ray maps of altered pentlandite from the main tailings lysimeter. Scale bar equals 20 micrometres. BSE image. The average composition of the rim is lower in nickel, slightly lower in sulfur and higher in iron concentration than the pentlandite core. Cobalt is approximately equal in both phases and copper is slightly elevated in the rim. The relationship shown on the sulfur and oxygen x-ray maps in figure 7.12b, suggests that the darker grey phase on the BSE image is an oxyhydroxide, and the lighter grey phase is a sulfate. A less well developed rim and alteration along fractures can be seen on the oxidized pentlandite grain in figures 7.13a and 7.13b. The replacement phase is an iron oxyhydroxide depleted in both nickel and cobalt relative to the original pentlandite. The oxidation of pentlandite to iron oxyhydroxide can also be seen in figures 7.14a and 7.14b. The analytical results show high sulfur content in the rim, possibly a result of adsorbed sulfate or contamination by residual sulfide present just below the surface. The presence of sulfur is also discernible on the multi- element x-ray maps. A fourth example of pentlandite alteration is shown in (figure 7.15). The oxidation rim is well developed compared to the preceding two examples, but is similar in composition. The rim is an iron oxyhydroxide with less cobalt and nickel than its parent pentlandite. The rim shows a slight zonation delineated by grey levels that darken with distance from the centre. The chalcopyrite oxidation rim in Figure 7.16 occurs at a depth of 7.5 cm. In contrast to the leached appearance usually exhibited by oxidized chalcopyrite in tailings environments, this grain shows evidence of rim oxidation as well as oxidation along fractures. The rim is an iron oxyhydroxide. The grain was too small to obtain quantitative EPMA results. wt.% (1J (2) S 33.52 33.64 Ti 0.01 0.02 Cr 0.00 0.04 Mn 0.00 0.02 Fe 30.25 30.28 Co 0.94 0.93 Ni 35.39 35.39 Cu 0.00 0.00 Zn 0.00 0.00 As 0.00 0.02 Cd 0.00 0.00 Sb 0.00 0.00 Pb 0.00 0.00 Atomic proportion S 1.05 1.05 Ti 0.00 0.00 Cr 0.00 0.00 Mn 0.00 0.00 Fe 0.54 0.54 Co 0.02 0.02 Ni 0.60 0.60 Cu 0.00 0.00 Zn 0.00 0.00 As 0.00 0.00 Cd 0.00 0.00 Sb 0.00 0.00 Pb 0.00 0.00 © © ® ® 33.39 33.48 6.52 6.05 0.01 0.01 0.01 0.00 0.01 0.03 0.00 0.00 0.00 0.00 0.03 0.01 30.91 29.88 47.64 48.08 0.92 0.84 0.12 0.09 35.40 35.35 4.12 3.27 0.00 0.00 0.17 0.13 0.00 0.00 0.00 0.01 0.00 0.00 0.01 0.00 0.02 0.02 0.02 0.02 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 1.04 1.04 0.20 0.19 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.55 0.54 0.85 0.86 0.02 0.01 0.00 0.00 0.60 0.60 0.07 0.06 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Figure 7.13a: B S E image and corresponding E P M A results of altered pentlandite from the main tailings lysimeter (7.5 cm depth). Scale bar equals 20 micrometres. Figure 7.13b: Multi-element x-ray maps for altered pentlandite from the main tailings lysimeter. Scale bar equals 20 micrometres. wt.% [2J S 32.42 32.79 Ti 0.00 0.00 Cr 0.01 0.00 Mn 0.00 0.02 Fe 29.82 30.53 Co 1.76 1.73 Ni 34.80 34.70 Cu 0.00 0.00 Zn 0.01 0.00 As 0.00 0.06 Cd 0.08 0.03 Sb 0.00 0.00 Pb 0.00 0.00 Z45 0.02 0.00 0.32 47.49 0.19 2.78 0.35 0.23 0.00 0.02 0.00 0.03 4̂ 13T30 0.01 0.02 0.10 43.08 0.80 10.71 0.52 0.13 0.00 0.03 0.03 0.00 (5, 1.00 0.08 0.00 0.29 40.89 0.02 1.13 0.47 0.18 0.00 0.00 0.00 0.00 J6, 10.40 0.02 0.00 0.30 45.70 0.71 9.16 0.39 0.16 0.00 0.00 0.00 0.00 (7_ 1.16 0.06 0.01 0.15 34.99 0.05 1.37 0.65 0.07 0.00 0.00 0.00 0.06 2.20 0.05 0.01 0.19 43.05 0.04 1.24 0.57 0.06 0.00 0.00 0.00 0.06 (9J 15.79 0.00 0.01 0.11 41.26 1.14 15.71 0.41 0.03 0.01 0.00 0.00 0.00 (10) 15.13 0.08 0.01 0.01 45.43 0.01 0.81 1.38 0.06 0.00 0.00 0.00 0.00 Atomic proportion s 1.01 1.02 Ti 0.00 0.00 Cr 0.00 0.00 Mn 0.00 0.00 Fe 0.53 0.55 Co 0.03 0.03 Ni 0.59 0.59 Cu 0.00 0.00 Zn 0.00 0.00 As 0.00 0.00 Cd 0.00 0.00 Sb 0.00 0.00 Pb 0.00 0.00 0.08 0.41 0.03 0.32 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.01 0.00 0.01 0.01 0.85 0.77 0.73 0.82 0.00 0.01 0.00 0.01 0.05 0.18 0.02 0.16 0.01 0.01 0.01 0.01 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.04 0.07 0.49 0.47 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.63 0.77 0.74 0.81 0.00 0.00 0.02 0.00 0.02 0.02 0.27 0.01 0.01 0.01 0.01 0.02 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Figure 7.14a: B S E image and E P M A results for altered pentlandite from the main tailings lysimeter (15 cm depth). Scale bar equals 20 micrometres. Figure 7.14b: Multi-element x-ray maps of altered pentlandite from the main tailings lysimeter. Scale bar equals 20 micrometres. wt.% © ® © © © ® © S 33.28 30.32 3.31 4.52 4.36 3.71 12T54 Ti 0.00 0.01 0.00 0.16 0.00 0.00 0.01 Cr 0.02 0.01 0.03 0.01 0.01 0.01 0.03 Mn 0.03 0.00 0.00 0.05 0.00 0.04 0.00 Fe 30.87 30.28 52.32 43.36 50.95 46.72 42.83 Co 0.97 0.84 0.10 0.03 0.08 0.02 0.31 Ni 34.45 32.66 1.85 1.35 1.63 1.37 12.54 Cu 0.00 0.00 0.15 0.12 0.16 0.11 0.11 Zn 0.01 0.00 0.00 0.01 0.01 0.05 0.00 As 0.00 0.03 0.03 0.00 0.02 0.00 0.00 Cd 0.00 0.00 0.00 0.04 0.01 0.00 0.00 Sb 0.01 0.00 0.00 0.00 0.00 0.00 0.00 Pb 0.00 0.00 0.04 0.00 0.01 0.00 0.00 Atomic proportion S 1.04 0.95 0.10 0.14 0.14 0.12 0.39 Ti 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Cr 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Mn 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Fe 0.55 0.54 0.94 0.78 0.91 0.84 0.77 Co 0.02 0.01 0.00 0.00 0.00 0.00 0.01 Ni 0.59 0.56 0.03 0.02 0.03 0.02 0.21 Cu 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Zn 0.00 0.00 0.00 0.00 0.00 0.00 0.00 As 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Cd 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Sb 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Pb 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Figure 7.15: BSE image and corresponding EPMA results of an altered pentlandite from the main tailings lysimeter (5 cm depth). Scale bar equals 20 micrometres. 134 Figure 7.16: Multi-element x-ray maps and BSE image of altered chalcopyrite from the main tailings lysimete. Scale bar equals 10 micrometres. Grains of coexisting pyrrhotite and pentlandite from the unsaturated zone were examined to determine relative oxidation of the two sulfides as well as to examine the nickel distribution in the secondary phases. Figures 7.17a and 7.17b show this type of relationship. In all cases the pyrrhotite oxidized faster than pentlandite, producing an iron oxyhydroxide. The multi-element x-ray maps showed no significant nickel accumulation in the iron oxyhydroxide. Another example of a multi-mineralic grain in which relative rates of oxidation can be compared is given in figures 7.18a and 7.18b. Pyrrhotite, represented by analysis point number 3, is the only sulfide exhibiting significant oxidation textures. Pentlandite, point number 4, is slightly depleted in nickel and is mottled on the surface. Fractures in both the chalcopyrite, points 1 and 2, and the feldspar, the large, dark grey mineral on the left of the image, are filled with iron oxyhydroxide, but the edges of both primary minerals are sharp and unaltered. An iron oxyhydroxide, averaging 0.70 wt. % Ni, has served to cement the minerals together. Figures 7.19a and 7.19b represent oxidized pyrrhotite in a multi-mineralic aggregate also comprised of unaltered chlorite, biotite, ilmenite, and quartz as marked on the BSE image. Pyrrhotite has been replaced by intermixed native sulfur, as indicated by the darker grey material near point number 4, and iron oxyhydroxide, with possible associated sulfate, and covellite, interpreted from the copper x-ray map. The secondary mixture contains up to 1.70 wt. % Cu and 0.84 wt. % Ni. The iron oxyhydroxide phase is also found as a thin rim around the entire aggregate and between the cleavage planes of the coexisting biotite and chlorite. 136 Atomic proportion s 1.02 1.23 Ti 0.00 0.00 Cr 0.00 0.00 Mn 0.00 0.00 Fe 0.55 1.08 Co 0.01 0.00 Ni 0.61 0.01 Cu 0.00 0.00 Zn 0.00 0.00 As 0.00 0.00 Cd 0.00 0.00 Sb 0.00 0.00 Pb 0.00 0.00 1.20 0.18 0.54 0.36 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 1.07 0.95 0.72 0.92 0.00 0.00 0.00 0.00 0.01 0.00 0.22 0.01 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.42 0.01 0.02 0.01 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.85 0.84 0.83 0.85 0.00 0.00 0.00 0.00 0.00 0.03 0.03 0.03 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Figure 7.17a: BSE image and corresponding EPMA results for altering pyrrhotite with pentlandite from the main tailings lysimeter (15 cm depth). Scale bar equals 50 micrometres. Figure 7.17b: Multi-element x-ray maps for partly altered pyrrhotite and pentlandite from the main tailings lysimeter. Scale bar equals 50 micrometres. 138 Atomic proportion S 0.89 1.10 Ti 0.00 0.00 Cr 0.00 0.00 Mn 0.00 0.00 Fe 0.61 0.55 Co 0.00 0.00 Ni 0.00 0.00 Cu 0.44 0.54 Zn 0.00 0.00 As 0.00 0.00 Cd 0.00 0.00 Sb 0.00 0.00 Pb 0.00 0.00 0.53 0.85 0.04 0.07 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.86 0.65 0.91 0.88 0.00 0.01 0.00 0.00 0.01 0.44 0.02 0.01 0.00 0.00 0.00 0.01 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.22 0.03 0.0351 0.35 0.00 0.01 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.57 0.71 0.79 0.72 0.00 0.00 0.00 0.00 0.01 0.01 0.01 0.01 0.04 0.00 0.00 0.16 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Figure 7.18a: B S E image and corresponding E P M A results for a multi-mineralic association from the main tailings lysimeter (50 cm depth). Scale bar equals 50 micrometres. 139 Figure 7.18b: Multi-element x-ray maps and BSE image of altered pyrrhotite coexisting with pentlandite, chalcopyrite, and feldspar from the main tailings lysimeter. Scale bar equals 50 micrometres. 140 Figure 7.19a: B S E image and corresponding E P M A results for altered pyrrhotite from the main tailings lysimeter (25 cm depth). Scale bar equals 50 micrometres;Chl=chlorite, Bi=biotite, Qtz=quartz, and llm=ilmenite. Figure 7.19b: Multi-element x-ray maps of altered pyrrhotite coexisting with biotite, ilmenite quartz, and chlorite from the main tailings lysimeter. Scale bar equals 50 micrometres. 142 Total tailings lysimeter Alteration of sulfides in the unsaturated zone of the total tailings lysimeter has progressed to a greater degree than in either the low sulfur tailings or main tailings lysimeters. Pyrrhotite oxidation ranged from well formed oxidation rims to complete pseudomorphic replacements. The grain shown in figures 7.20a and 7.20b is pyrrhotite that has been partly replaced by rims of covellite, a sulfate, and an iron oxyhydroxide, in that order. The results of the electron probe microanalysis show that the nickel content is slightly higher in the oxidation rims than in the original grain. The pseudomorphic replacement shown in figures 7.21a and 7.21b contains a relict core of pyrrhotite (point 1), a feldspar inclusion (above 1 and 3), and a circular grain of pentlandite (point 2). The bulk of the pseudomorph is comprised predominantly of iron oxyhydroxide with adsorbed sulfur, likely as sulfate that is surrounded by a thin outer iron oxyhydroxide rim depleted in sulfur. No appreciable nickel is present in either alteration phase; however, the copper content averages 0.11 wt. % in the pseudomorph and was not detected in the original pyrrhotite. A grain mount of this pseudomorph was analyzed via Debye-Scherrer x-ray methods and resulted in the identification of pentlandite, quartz, and pyrrhotite which suggests that the bulk of the pseudomorph is poorly crystalline. Figures 7.22a and 7.22b show an ilmenite inclusion in a completely oxidized pyrrhotite that is similar to the pseudomorph described in the preceding figure This grain was also analyzed by Debye- Scherrer x-ray diffractometry resulting in the identification of the ilmenite inclusion. The pseudomorphic material, however did not diffract and suggests that it is poorly crystalline. On the basis of the electron probe data and multi-element x-ray maps, the replacement is interpreted to have taken place by two phases, native sulfur and an iron oxyhydroxide. The native sulfur occurs sporadically in the core of the wt.% (JJ (2) S 39.51 39̂ 61 Ti 0.01 0.00 Cr 0.00 0.00 Mn 0.01 0.00 Fe 59.56 60.01 Co 0.02 0.00 Ni 0.25 0.26 Cu 0.12 0.07 Zn 0.00 0.00 As 0.02 0.04 Cd 0.00 0.00 Sb 0.00 0.01 Pb 0.00 0.00 © © © ® 10.36 5.56 8.15 13.18 0.00 0.00 0.00 0.00 0.01 0.00 0.02 0.01 0.04 0.03 0.01 0.01 33.27 43.31 40.03 52.72 0.03 0.03 0.01 0.00 0.41 0.43 0.36 0.49 19.13 4.49 6.95 0.91 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.03 0.00 0.01 0.00 0.00 0.01 0.01 0.00 0.00 0.00 0.00 0.00 /—\ (7J © © ® 1.91 39.96 41.14 15.13 0.00 0.03 0.02 0.08 0.01 0.01 0.00 0.01 0.03 0.00 0.01 0.01 25.16 60.45 40.45 45.43 0.01 0.00 0.00 0.01 0.26 0.50 0.84 0.81 1.85 0.03 0.07 1.38 0.05 0.01 0.00 0.06 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.02 0.00 0.01 0.00 0.00 0.00 Atomic proportion s 1.23 1.24 0.32 0.17 0.25 0.41 0.06 1.25 1.28 0.47 Ti 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Cr 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Mn 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Fe 1.07 1.07 0.60 0.78 0.72 0.94 0.45 1.08 0.72 0.81 Co 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Ni 0.00 0.00 0.01 0.01 0.01 0.01 0.00 0.01 0.01 0.01 Cu 0.00 0.00 0.30 0.07 0.11 0.01 0.03 0.00 0.00 0.02 Zn 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 As 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Cd 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Sb 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Pb 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Figure 7.20a: B S E image and corresponding E P M A results of altered pyrrhotite from the total tailings lysimeter (10 cm depth). Scale bar equals 20 micrometres. Figure 7.20b: Multi-element x-ray maps and BSE image of altered pyrrhotite from the total tailings lysimeter. Scale bar equals 20 micrometres. 145 Figure 7.21a: B S E image and corresponding E P M A results of pyrrhotite pseudomorph from thetotal tailings lysimeter (22 cm depth). Scale bar equals 100 micrometres. Figure 7.21b: Multi-element x-ray maps and BSE image of pyrrhotite pseudomorph from the total tailings lysimeter. Scale bar equals 50 micrometres. wt.% © (2) (3j (4J S 16.79 14.92 4.09 4.37 Ti 0.00 0.00 0.03 0.00 Cr 0.01 0.01 0.00 0.00 Mn 0.00 0.00 0.01 0.00 Fe 0.10 0.09 15.19 14.60 Co 0.00 0.00 0.00 0.00 Ni 0.00 0.00 0.09 0.14 Cu 0.01 0.00 0.10 0.09 Zn 0.00 0.01 0.00 0.00 As 0.00 0.00 0.02 0.00 Cd 0.00 0.00 0.00 0.00 Sb 0.00 0.00 0.00 0.00 Pb 0.00 0.00 0.00 0.00 Atomic proportion S 0.52 0.47 0.13 0.14 Ti 0.00 0.00 0.00 0.00 Cr 0.00 0.00 0.00 0.00 Mn 0.00 0.00 0.00 0.00 Fe 0.00 0.00 0.27 0.26 Co 0.00 0.00 0.00 0.00 Ni 0.00 0.00 0.00 0.00 Cu 0.00 0.00 0.00 0.00 Zn 0.00 0.00 0.00 0.00 As 0.00 0.00 0.00 0.00 Cd 0.00 0.00 0.00 0.00 Sb 0.00 0.00 0.00 0.00 Pb 0.00 0.00 0.00 0.00 ® © © © © © 16.85 4.78 3.45 29.07 15.79 15.13 0.00 0.00 0.01 0.00 0.00 0.08 0.01 0.00 0.01 0.00 0.01 0.01 0.00 0.00 0.00 0.02 0.11 0.01 0.18 19.70 37.54 32.44 41.26 45.43 0.00 0.00 0.00 1.03 1.14 0.01 0.00 0.13 0.09 20.42 15.71 0.81 0.01 0.04 0.13 0.14 0.41 1.38 0.00 0.00 0.00 0.02 0.03 0.06 0.00 0.00 0.00 0.00 0.01 0.00 0.01 0.00 0.01 0.01 0.00 0.00 0.00 0.01 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.53 0.15 0.11 0.91 0.49 0.47 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.35 0.67 0.58 0.74 0.81 0.00 0.00 0.00 0.02 0.02 0.00 0.00 0.00 0.00 0.35 0.27 0.01 0.00 0.00 0.00 0.00 0.01 0.02 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Figure 7.22a: B S E image and corresponding E P M A results of pyrrhotite pseudomorph from the total tailings lysimeter (22 cm depth). Scale bar equals 50 micrometres. Figure 7.22b: Multi-element x-ray maps and BSE image of pyrrhotite pseudomorph from the total tailings lysimeter. Scale bar equals 50 micrometres. 149 pseudomorph and is conspicuous in the x-ray map for sulfur. It is surrounded by a fine grained mixture of sulfur and iron oxyhydroxide which exhibits a ribbed texture resulting from crystallographically controlled replacement. The outermost rim consists of an iron oxyhydroxide. The electron probe microanalysis results and the x-ray maps for copper and nickel show that both metals, although low in concentration, are associated with the iron oxyhydroxide, but not with the native sulfur. Another pseudomorph is shown in figures 7.23a and 7.23b. The centre of the grain is predominantly native sulfur and an intergrown iron sulfate rimmed by a surrounding iron oxyhydroxide. Nickel and copper contents are low in the iron oxyhydroxide phase, even lower in the iron sulfate oxidation product and undetected in the native sulfur. The ribbed texture exhibited by the pseudomorphic mixture of native sulfur and iron oxyhydroxide described in figure 7.22 is also illustrated by the example shown in figures 7.24a and 7.24b. The pseudomorphs in this example are comprised of iron oxyhydroxide. There is negligible nickel present in the pseudomorphs, but the copper concentration averages 0.28 wt. %. Sulfide oxidation has progressed further in the oxidation columns than it has in the corresponding lysimeter for each of the three tailings types. Examples of the alterations occurring in the oxidation columns are described below. Low sulfur tailings oxidation column A common secondary phase resulting from the oxidation of pyrrhotite in the lysimeters and in the oxidation columns is iron oxyhydroxide as seen in figures 7.25a and 7.25b. Another similarity between the oxidation occurring in the lysimeters and in the columns is that the iron oxyhydroxide alteration product wt.% S 8.12 Ti 0.00 Cr 0.00 Mn 0.00 Fe 18.17 Co 0.00 Ni 0.15 Cu 0.12 Zn 0.00 As 0.00 Cd 0.00 Sb 0.00 Pb 0.00 Atomic proportion S 0.25 Ti 0.00 Cr 0.00 Mn 0.00 Fe 0.33 Co 0.00 Ni 0.00 Cu 0.00 Zn 0.00 As 0.00 Cd 0.00 Sb 0.00 Pb 0.00 D © © 9.39 9.03 10.79 0.01 0.00 0.00 0.00 0.01 0.00 0.00 0.00 0.01 3.09 10.90 13.19 0.00 0.02 0.00 0.01 0.05 0.10 0.02 0.05 0.10 0.02 0.00 0.02 0.00 0.00 0.00 0.01 0.00 0.00 0.01 0.00 0.00 0.00 0.00 0.00 0.29 0.28 0.34 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.06 0.20 0.24 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 © ® © 10.57 3.85 3.45 0.00 0.03 0.01 0.00 0.02 0.01 0.00 0.01 0.00 17.84 40.66 37.54 0.00 0.00 0.00 0.02 0.02 0.09 0.09 0.13 0.13 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.01 0.00 0.00 0.00 0.00 0.01 0.00 0.33 0.12 0.11 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.32 0.73 0.67 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 © © © 29.07 15.79 15.13 0.00 0.00 0.08 0.00 0.01 0.01 0.02 0.11 0.01 32.44 41.26 45.43 1.03 1.14 0.01 20.42 15.71 0.81 0.14 0.41 1.38 0.02 0.03 0.06 0.00 0.01 0.00 0.01 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.91 0.49 0.47 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.58 0.74 0.81 0.02 0.02 0.00 0.35 0.27 0.01 0.00 0.01 0.02 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Figure 7.23a: B S E image and corresponding E P M A results of pyrrhotite pseudomorph from the total tailings lysimeter (22 cm depth). Scale bar equals 50 micrometres. Figure 7.23b: Multi-element x-ray maps and BSE image of pyrrhotite pseudomorph from the total tailings lysimeter. Scale bar equals 50 micrometres. wt.% © © © © © ® © S 4.01 2.87 4.02 278 3.33 2.81 34.38 Ti 0.02 0.01 0.02 0.01 0.03 0.03 0.00 Cr 0.00 0.01 0.00 0.01 0.02 0.01 0.00 Mn 0.01 0.00 0.00 0.01 0.00 0.00 0.00 Fe 55.51 51.99 40.74 36.19 45.45 50.79 32.07 Co 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Ni 0.00 0.05 0.05 0.10 0.04 0.03 0.84 Cu 0.33 0.37 0.27 0.17 0.25 0.29 0.00 Zn 0.00 0.01 0.00 0.00 0.00 0.00 0.00 As 0.04 0.00 0.00 0.00 0.00 0.00 0.02 Cd 0.02 0.00 0.02 0.00 0.03 0.00 0.01 Sb 0.00 0.01 0.00 0.00 0.00 0.00 0.00 Pb 0.00 0.00 0.00 0.01 0.03 0.00 0.00 Atomic proportion S 0.12 0.09 0.13 0.09 0.10 0.09 1.07 Ti 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Cr 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Mn 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Fe 0.99 0.93 0.73 0.65 0.81 0.91 0.57 Co 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Ni 0.00 0.00 0.00 0.00 0.00 0.00 0.01 Cu 0.01 0.01 0.00 0.00 0.00 0.00 0.00 Zn 0.00 0.00 0.00 0.00 0.00 0.00 0.00 As 0.00 0.00 0.00 0.00 0.00 0.00 0 00 Cd 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Sb 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Pb 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Figure 7.24a: BSE image and corresponding EPMA results for pyrrhotite pseudomorphs from the total tailings lysimeter (22 cm depth). Scale bar equals 20 micrometres. Figure 7.24b: Multi-element x-ray maps and BSE image of pyrrhotite pseudomorphs from the total tailings lysimeter. Scale bar equals 50 micrometres. wt.% © ® © © © © © S 39.66 37.98 12.52 3.65 2.75 7.75 11.88 10.30 Ti 0.00 0.01 0.02 0.02 0.00 0.02 0.01 0.00 Cr 0.00 0.01 0.01 0.00 0.00 0.00 0.02 0.00 Mn 0.01 0.00 0.02 0.04 0.02 0.00 0.02 0.01 Fe 59.78 60.04 48.29 53.61 55.23 49.61 49.60 48.87 Co 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Ni 0.56 0.58 0.17 0.20 0.20 0.14 0.20 0.14 Cu 0.01 0.13 0.16 0.15 0.11 0.19 0.25 0.20 Zn 0.00 0.00 0.00 0.04 0.00 0.02 0.03 0.01 As 0.00 0.00 0.01 0.01 0.01 0.00 0.00 0.01 Cd 0.00 0.00 0.00 0.00 0.02 0.00 0.00 0.00 Sb 0.01 0.00 0.01 0.02 0.02 0.00 0.00 0.00 Pb 0.00 0.00 0.00 0.00 0.00 0.00 0.01 0.00 Atomic proportion S 1.24 1.18 0.39 0.11 0.09 0.24 0.37 0.32 Ti 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Cr 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Mn 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Fe 1.07 1.08 0.86 0.96 0.99 0.89 0.89 0.88 Co 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Ni 0.01 0.01 0.00 0.00 0.00 0.00 0.00 0.00 Cu 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Zn 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 As 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Cd 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Sb 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Pb 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Figure 7.25a: B S E image and E P M A results for altered pyrrhotite from low sulfur tailings oxidation column (7.5 cm depth). Scale bar equals 50 micrometres. Figure 7.25b: Multi-element x-ray maps and BSE image of altered pyrrhotite from the low sulfur tailings oxidation column. Scale bar equals 50 micrometres. 156 precipitated in situ has a lower nickel content than the precursor pyrrhotite. Copper was detected in the oxidation product from this grain. The oxidation of another pyrrhotite grain, slightly more nickeliferous than the last example, resulted in two alteration products, (figures 7.26a and 7.26b) identified by Debye-Scherrer x-ray diffraction as goethite (a-Fe 3 +0 OH) and lepidocrocite (y-Fe3+0 OH). Textural differences, as well as chemical differences can be seen between the two iron oxyhydroxides, one is irregular in texture and averages 0.63 wt. % Ni and 0.18 wt. % Cu, whereas the other is homogenous and smooth texture and contains approximately 0.35 wt. % Ni, 0.09 wt. % Cu, and significantly more residual sulfur, likely as sulfate, than the other iron oxyhydroxide. Two oxidation phases, similar in texture to the two iron oxyhydroxides in the last example, were seen in the oxidized pyrrhotite in figures 7.27a and 7.27b. In contrast to the previous example, however, nickel and copper concentrations are not more strongly associated with one phase than the other, and are equally low in concentration in both alteration phases. Pyrrhotite and possibly goethite were the phases identified by Debye-Scherrer x-ray analysis in the grain mount made from this grain. Figures 7.28a and 7.28b show the oxidation of a nickel-poor pyrrhotite coexisting with a small grain of unaltered pentlandite. The resulting secondary phases are an iron oxyhydroxide and an iron sulfate. No appreciable nickel is associated with either phase, averaging 0.30 wt. % Ni in the iron oxyhydroxide and 0.13 wt. % Ni in the iron sulfate. Copper was detected in the alteration phases, but not in the primary pyrrhotite or in the pentlandite. wt.% (l_j S 39/16 Ti 0.00 Cr 0.03 Mn 0.00 Fe 60.02 Co 0.00 Ni 0.86 Cu 0.01 Zn 0.02 As 0.00 Cd 0.02 Sb 0.00 Pb 0.00 Atomic proportion S 1.22 Ti 0.00 Cr 0.00 Mn 0.00 Fe 1.07 Co 0.00 Ni 0.01 Cu 0.00 Zn 0.00 As 0.00 Cd 0.00 Sb 0.00 Pb 0.00 (2) (3J (4J (5) 39̂ 44 39.37 12.70 9.89 0.01 0.00 0.01 0.00 0.00 0.02 0.00 0.00 0.01 0.01 0.00 0.00 60.68 60.19 47.52 50.25 0.00 0.00 0.00 0.00 0.81 0.67 0.34 0.46 0.00 0.00 0.13 0.06 0.00 0.00 0.00 0.00 0.02 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.03 0.02 0.00 0.02 0.00 0.00 0.00 0.00 (6J 8/30 0.01 0.00 0.00 50.95 0.00 0.25 0.11 0.00 0.00 0.00 0.00 0.02 (TJ 1.51 0.01 0.00 0.08 52.86 0.00 0.38 0.14 0.02 0.00 0.00 0.00 0.00 (8J 2.30 0.00 0.00 0.21 43.79 0.01 0.87 0.19 0.03 0.00 0.00 0.02 0.00 1.23 0.00 0.00 0.00 1.09 0.00 0.01 0.00 0.00 0.00 0.00 0.00 0.00 1.23 0.00 0.00 0.00 1.08 0.00 0.01 0.00 0.00 0.00 0.00 0.00 0.00 0.40 0.00 0.00 0.00 0.85 0.00 0.01 0.00 0.00 0.00 0.00 0.00 0.00 0.31 0.00 0.00 0.00 0.90 0.00 0.01 0.00 0.00 0.00 0.00 0.00 0.00 0.26 0.00 0.00 0.00 0.91 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.05 0.00 0.00 0.00 0.95 0.00 0.01 0.00 0.00 0.00 0.00 0.00 0.00 0.07 0.00 0.00 0.00 0.78 0.00 0.01 0.00 0.00 0.00 0.00 0.00 0.00 Figure 7.26a: B S E image and corresponding E P M A results for altered pyrrhotite from the low sulfur tailings column (7.5 cm depth). Scale bar equals 50 micrometres. Figure 7.26b: Multi-element x-ray maps of altered pyrrhotite from the low sulfur tailings oxidation column. Scale bar equals 100 micrometres. 159 Figure 7.27a: B S E image and corresponding E P M A results for altered pyrrhotite from the low sulfur tailings oxidation column (15 cm depth). Scale bar equals 50 micrometres. Figure 7.27b: Multi-element x-ray maps and BSE image of altered pyrrhotite from the low sulfur tailings oxidation column. Scale bar equals 50 micrometres. wt.% ( L ) S 39.50 Ti 0.01 Cr 0.00 Mn 0.00 Fe 60.32 Co 0.00 Ni 0.39 Cu 0.03 Zn 0.01 As 0.00 Cd 0.00 Sb 0.00 Pb 0.00 Atomic proportion S 1.23 Ti 0.00 Cr 0.00 Mn 0.00 Fe 1.08 Co 0.00 Ni 0.01 Cu 0.00 Zn 0.00 As 0.00 Cd 0.00 Sb 0.00 Pb 0.00 © 39.39 0.00 0.00 0.02 60.83 0.01 0.49 0.00 0.01 0.00 0.00 0.00 0.00 © 33.35 0.01 0.00 0.00 30.24 1.71 34.51 0.00 0.00 0.00 0.00 0.00 0.00 (4J 13.51 0.02 0.01 0.01 46.07 0.00 0.12 0.06 0.00 0.01 0.01 0.00 0.00 © 12.72 0.01 0.01 0.01 47.08 0.01 0.14 0.11 0.01 0.03 0.01 0.00 0 00 © 3.53 0.00 0.00 0.02 54.18 0.00 0.41 0.07 0.03 0.00 0.00 0.00 0.00 © 6.46 0.00 0.00 0.02 51.98 0.00 0.20 0.17 0.00 0.00 0.00 0.01 0.00 1.23 1.04 0.00 0.00 0.00 0.00 0.00 0.00 1.09 0.54 0.00 0.03 0.01 0.59 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.42 0.40 0.00 0.00 0.00 0.00 0.00 0.00 0.82 0.84 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.11 0.20 0.00 0.00 0.00 0.00 0.00 0.00 0.97 0.93 0.00 0.00 0.01 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Figure 7.28a: B S E image and corresponding E P M A results for altered pyrrhotite with pentlandite from the low sulfur tailings column (2.5 cm depth). Scale bar equals 20 micrometres. Figure 7.28b: Multi-element x-ray maps and BSE image of altered pyrrhotite with pentlandite from the low sulfur tailings oxidation column; the box and enlargement outline the area seen in maps. Scale bar equals 100 micrometres. 163 Main tailings oxidation column Oxidation in the main tailings oxidation column has progressed to the stage of locally complete pseudomorphic replacement of pyrrhotite. Figures 7.29a and 7.29b show the pseudomorphic replacement of pyrrhotite by at least one iron oxyhydroxide, and altered pentlandite cemented by another, compositionally different iron oxyhydroxide. The pseudomorphic iron oxyhydroxide phase has nickel contents ranging between 0.25 wt. % and 0.70 wt. %, and copper contents between 0.01 wt. % and 0.45 wt. %. The pseudomorphs also contain significant sulfur, most likely as admixed sulfate. The cementing iron oxyhydroxide, represented by the analysis points number six and number ten, contains approximately 0.52 wt. % Ni and less than 0.14 wt. % Cu. The sulfur x-ray map shows very little sulfur associated with the cementing phase, suggesting it precipitated from mobile solutions rather than from in situ oxidation. The pentlandite alteration product is characterized by a depletion in nickel and a mottled appearance. Total tailings oxidation column The pseudomorph in figures 7.30a and 7.30b is characterized by the ribbed texture often exhibited by a mixture of secondary phases, likely iron oxyhydroxide and sulfate. The space separating the core and the outer rim was most likely native sulfur that was lost when the section was polished. 7.2.3 Slag particles- Altered slag particles, although rare, are most evident in the unsaturated zone of the total tailings product. Multi-element x-ray maps and BSE images of the more strongly oxidized slag particles were completed to determine if heavy metals present in the slag are being leached or remain in situ with the secondary phases produced by oxidation. wt.% CD (2) (3j> CD S 5.11 1.99 0.63 3.43 Ti 0.02 0.01 0.00 0.00 Cr 0.00 0.01 0.00 0.01 Mn 0.01 0.01 0.03 0.01 Fe 49.47 55.30 54.10 54.24 Co 0.01 0.00 0.02 0.00 Ni 3.08 0.34 0.44 0.27 Cu 0.10 0.44 0.02 0.42 Zn 0.00 0.03 0.00 0.00 As 0.00 0.00 0.02 0.00 Cd 0.00 0.02 0.00 0.00 Sb 0.00 0.02 0.00 0.00 Pb 0.00 0.09 0.00 0.02 Atomic proportion S 0.16 0.06 0.02 0.11 Ti 0.00 0.00 0.00 0.00 Cr 0.00 0.00 0.00 0.00 Mn 0.00 0.00 0.00 0.00 Fe 0.89 0.99 0.97 0.97 Co 0.00 0.00 0.00 0.00 Ni 0.05 0.01 0.01 0.00 Cu 0.00 0.01 0.00 0.01 Zn 0.00 0.00 0.00 0.00 As 0.00 0.00 0.00 0.00 Cd 0.00 0.00 0.00 0.00 Sb 0.00 0.00 0.00 0.00 Pb 0.00 0.00 0.00 0.00 © © ® ® ® ® 4.96 0.77 5.96 34.39 34.99 1.21 0.01 0.00 0.04 0.01 0.01 0.03 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.01 0.01 0.00 0.03 51.39 50.92 50.28 31.42 28.39 52.35 0.00 0.03 0.02 0.80 0.91 0.00 0.37 0.55 0.70 22.01 23.75 0.49 0.45 0.01 0.17 0.81 0.49 0.14 0.03 0.04 0.00 0.01 0.00 0.04 0.00 0.00 0.02 0.00 0.01 0.00 0.00 0.00 0.00 0.00 0.05 0.00 0.00 0.00 0.01 0.00 0.00 0.00 0.00 0.01 0.00 0.00 0.00 0.00 0.15 0.02 0.19 1.07 1.09 0.04 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.92 0.91 0.90 0.56 0.51 0.94 0.00 0.00 0.00 0.01 0.02 0.00 0.01 0.01 0.01 0.38 0.40 0.01 0.01 0.00 0.00 0.01 0.01 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Figure 7.29a: B S E image and corresponding E P M A results for pyrrhotite pseudomorphs and altered pentlandite from the main tailings column (5 cm depth). Scale bar equals 20 micrometres. 165 Figure 7.29b: Multi-element x-ray maps and BSE image of pyrrhotite pseudomorphs cemented to altered pentlandite from the main tailings oxidation column. Scale bar equals 20 micrometres. 166 Atomic proportion S 0.09 0.13 Ti 0.00 0.00 Cr 0.00 0.00 Mn 0.00 0.00 Fe 0.74 0.79 Co 0.00 0.00 Ni 0.00 0.00 Cu 0.00 0.00 Zn 0.00 0.00 As 0.00 0.00 Cd 0.00 0.00 Sb 0.00 0.00 Pb 0.00 0.00 0.10 0.21 0.10 0.11 0.00 0.00 0.00 0.01 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.61 0.91 0.89 0.91 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.09 1.25 1.28 0.47 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.76 1.08 0.72 0.81 0.00 0.00 0.00 0.00 0.00 0.01 0.01 0.01 0.00 0.00 0.00 0.02 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Figure 7.30a: B S E image and corresponding E P M A results pyrrhotite pseudomorph from the total tailings oxidation column (15 cm depth). Scale bar equals 50 micrometres. Figure 7.30b: Multi-element x-ray maps of pyrrhotite pseudomorph from the total tailings oxidation column. Scale bar equals 20 micrometres. 168 Figures 7.31a and 7.31b show a slag particle comprised of two dominant phases, a copper sulfide and a nickel sulfide, the latter containing up to 0.77 wt. % Co and 0.14 wt. % As. The entire particle is surrounded by two secondary phases, a complete rim of iron oxyhydroxide, and sporadic grains of covellite, both of which are interpreted to have formed within the tailings. Nickel shows a weak affinity to the iron oxyhydroxide as depicted by the nickel x-ray map. The tear-shaped slag particle shown in figures 7.32 also consists of a nickel sulfide and a copper sulfide. The surrounding covellite grains are interpreted to have formed after deposition of the particle in the tailings. The concentration of nickel is depleted on the rims of the grain. Quantitative electron microprobe analysis was not completed on this grain. Figures 7.33a and 7.33b are similar to those of the preceding example. The particle is composed of nickel sulfide and a copper sulfide. The oxidation of this slag particle consists of a rim of ferrugineous nickel oxide that is surrounded by numerous grains of covellite. A thicker oxidation rim has developed around the particle in figures 7.34a and 7.34b. The original particle is composed of nickel, copper, iron, and sulfur, with cobalt concentrations averaging 0.32 wt. %. The oxidation rim contains predominantly copper and sulfur, and minor iron. No appreciable nickel or cobalt remain in the rim phase. Quantitative electron microprobe analyses were done on a few other slag particles that had undergone less oxidation in order to get a range in slag composition. Figure 7.35 shows a slag particle that is predominantly metallic nickel. It contains approximately 10 wt. % Cu, 2.70 wt. % Fe and 1.75 wt. % Co. A thin oxidation rim, slightly higher in iron and sulfur and depleted with respect to nickel and cobalt, has developed. Figure 7.31a: B S E image and corresponding E P M A results an altered slag particle from the total tailings lysimeter (25 cm depth). Scale bar equals 10 micrometres. Figure 7.31b: Multi-element x-ray maps of partly altered slag particle from the total tailings lysimeter. Scale bar equals 10 micrometres.  wt.% © © © © S 31.85 27.03 29.39 28.45 Ti 0.02 0.01 0.04 0.03 Cr 0.00 0.03 0.00 0.02 Mn 0.00 0.01 0.00 0.00 Fe 0.80 0.68 0.54 0.67 Co 0.06 0.05 0.05 0.12 Ni 63.26 17.25 67.01 65.23 Cu 2.92 55.16 2.89 3.28 Zn 0.02 0.00 0.02 0.02 As 0.13 0.00 0.03 0.07 Cd 0.00 0.04 0.00 0.00 Sb 0.00 0.00 0.04 0.01 Pb 0.00 0.00 0.00 0.00 Atomic proportion s 0.99 0.84 0.92 0.89 Ti 0.00 0.00 0.00 0.00 Cr 0.00 0.00 0.00 0.00 Mn 0.00 0.00 0.00 0.00 Fe 0.01 0.01 0.01 0.01 Co 0.00 0.00 0.00 0.00 Ni 1.08 0.29 1.14 1.11 Cu 0.05 0.87 0.05 0.05 Zn 0.00 0.00 0.00 0.00 As 0.00 0.00 0.00 0.00 Cd 0.00 0.00 0.00 0.00 Sb 0.00 0.00 0.00 0.00 Pb 0.00 0.00 0.00 0.00 Figure 7.33a: B S E image and corresponding E P M A results of altered slag particle in total tailings lysimeter (25 cm depth). Scale bar equals 10 micrometres. Figure 7.33b: Multi-element x-ray maps and BSE image of partly altered slag particle from the total tailings lysimeter. Scale bar equals 10 micrometres. wt.% (1J S 28.94 Ti 0.02 Cr 0.03 Mn 0.02 Fe 10.85 Co 0.17 Ni 6.52 Cu 41.93 Zn 0.00 As 0.04 Cd 0.00 Sb 0.02 Pb 0.00 ® © C4J 31.69 35.04 5.25 0.00 0.00 0.02 0.00 0.02 0.01 0.01 0.00 0.00 3.35 2.89 1.46 0.21 0.45 0.01 27.71 41.37 0.07 30.03 15.02 11.12 0.00 0.01 0.00 0.05 0.05 0.00 0.02 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Atomic proportion s 0.90 0.99 1.09 0.16 Ti 0.00 0.00 0.00 0.00 Cr 0.00 0.00 0.00 0.00 Mn 0.00 0.00 0.00 0.00 Fe 0.19 0.06 0.05 0.03 Co 0.00 0.00 0.01 0.00 Ni 0.11 0.47 0.70 0.00 Cu 0.66 0.47 0.24 0.17 Zn 0.00 0.00 0.00 0.00 As 0.00 0.00 0.00 0.00 Cd 0.00 0.00 0.00 0.00 Sb 0.00 0.00 0.00 0.00 Pb 0.00 0.00 0.00 0.00 Figure 7.34a: B S E image and corresponding E P M A results for altered slag particle from the total tailings lysimeter (20 cm depth). Scale bar equals 10 micrometres. Figure 7.34b: Multi-element x-ray maps and BSE image of altered slag particle from the total tailings lysimeter. Scale bar equals 10 micrometres. wt.% © © © © © ® © s 0.05 1.62 16.06 4.13 0.16 2.19 16.58 Ti 0.00 0.00 0.01 0.01 0.02 0.00 0.04 Cr 0.00 0.00 0.00 0.00 0.00 0.00 0.02 Mn 0.02 0.01 0.27 0.01 0.03 0.00 0.22 Fe 1.79 1.68 3.27 5.11 2.24 1.58 3.19 Co 1.97 1.86 1.02 2.19 1.88 1.80 0.59 Ni 86.11 83.41 37.92 69.87 76.18 82.37 38.05 Cu 9.38 10.40 9.30 11.40 9.79 10.66 9.67 Zn 0.00 0.00 0.01 0.03 0.02 0.02 0.00 As 0.01 0.14 0.54 0.21 0.07 0.12 0.65 Cd 0.02 0.00 0.05 0.01 0.03 0.00 0.03 Sb 0.00 0.00 0.00 0.00 0.03 0.02 0.05 Pb 0.01 0.00 0.00 0.00 0.00 0.09 0.00 Atomic proportion s 0.00 0.05 0.50 0.13 0.01 0.07 0.52 Ti 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Cr 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Mn 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Fe 0.03 0.03 0.06 0.09 0.04 0.03 0.06 Co 0.03 0.03 0.02 0.04 0.03 0.03 0.01 Ni 1.47 1.42 0.65 1.19 1.30 1.40 0.65 Cu 0.15 0.16 0.15 0.18 0.15 0.17 0.15 Zn 0.00 0.00 0.00 0.00 0.00 0.00 0.00 As 0.00 0.00 0.01 0.00 0.00 0.00 0.01 Cd 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Sb 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Pb 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Figure 7.35: B S E image and corresponding E P M A results for altered slag particle from the total tailings lysimeter (25 cm depth). Scale bar equals 50 micrometres. 177 The grain shown in figure 7.36 is surrounded by a few sporadic grains of covellite, but doesn't show any other signs of significant oxidation. It is predominantly copper and sulfur with lesser and variable amounts of nickel and iron. 7.3 Chapter Summary Electron probe microanalysis was used to quantitatively identify many of the primary minerals in the tailings, the results of which are tabulated in section 7.1. In summary, it was determined that: • the composition of plagioclase ranges in An content from A n 6 to A n 7 ) , • the amphiboles are calcic in composition, but variable within that group, • biotite is present, but phlogopite is not, • chlorite in the tailings is predominantly ferroan clinochlore and chamosite, • pyroxenes are comprised of enstatite and augite, • pyrrhotite is best represented by the formula Fe0 87S, • and pentlandite is best represented by the formula (Ni455,Fe4 27Coo . i5)£=8.97S8. There are no trends seen between the three tailings types with respect to compositions of the primary minerals. Characterization of the alteration of primary minerals was achieved by a combination of electron probe microanalysis, scanning electron microscopy, multi-element x-ray map techniques and Debye- Scherrer x-ray methods. Biotite alteration is apparent in the total tailings lysimeter, total tailings column, and main tailings column, and is initially recognized by a depletion of potassium, followed by a decrease in iron and magnesium and a subsequent increase in silica until an end product similar to cristobalite is wt.% (V) ( 2 ) (3 j (A) S 27.61 26^85 29.93 27.75 Ti 0.03 0.00 0.00 0.00 Cr 0.00 0.00 0.01 0.00 Mn 0.01 0.03 0.00 0.01 Fe 3.75 3.65 2.36 2.96 Co 0.07 0.03 0.47 0.19 Ni 3.05 1.98 19.67 9.06 Cu 64.99 67.32 49.36 60.45 Zn 0.29 0.00 0.00 0.00 As 0.04 0.01 0.01 0.00 Cd 0.00 0.00 0.01 0.03 Sb 0.00 0.00 0.00 0.00 Pb 0.00 0.00 0.00 0.00 Atomic proportion S 0.86 0.84 0.93 0.87 Ti 0.00 0.00 0.00 0.00 Cr 0.00 0.00 0.00 0.00 Mn 0.00 0.00 0.00 0.00 Fe 0.07 0.07 0.04 0.05 Co 0.00 0.00 0.01 0.00 Ni 0.05 0.03 0.34 0.15 Cu 1.02 1.06 0.78 0.95 Zn 0.00 0.00 0.00 0.00 As 0.00 0.00 0.00 0.00 Cd 0.00 0.00 0.00 0.00 Sb 0.00 0.00 0.00 0.00 Pb 0.00 0.00 0.00 0.00 Figure 7.36: B S E image and corresponding E P M A results altered slag particle from the total tailings lysimeter (5 cm depth). Scale bar equals 10 micrometres. 179 achieved. The more strongly altered biotite from the tailings is represented by the formula Ko.08(Feo.35Mg0.15)s=0.5o(Alo.26Tio.04)Si3.oo- The secondary phases resulting from the oxidation of pyrrhotite include goethite, lepidocrocite, native sulfur, covellite, and possibly a sulfate phase. The degree to which oxidation of pyrrhoitite has occurred is strongest in the total tailings, often resulting in complete pseudomorphic replacements; intermediate in the main tailings, with vestiges of pyrrhotite commonly retained within the replacement phases; and weakest in the low sulfur tailings, dominated by fracture-controlled replacement and oxidation rims. Oxidation of pyrrhotite has progressed further in the oxidation columns than in their corresponding field lysimeters. The oxidation of pentlandite commonly results in replacement by iron oxyhydroxides, and is most pronounced in the main tailings and total tailings oxidation columns, but is also evident in the low sulfur tailings column, and all three field lysimeters. Slag particles, although rare, are present in all three tailings types, and vary with respect to composition. The alteration of these slags is most strongly developed in the total tailings, and negligible in the other two tailings types. Covellite and iron oxyhydroxides are the secondary products most commonly associated with the alteration of slag. 180 8.0 C O N C L U S I O N S This study comprises the mineralogical component of a larger project investigating a low sulfur tailings product as a potential cover material in the closure strategy of Inco Ltd.'s Copper Cliff tailings area. It was the purpose of this thesis to provide the baseline against which progressive mineral alteration in the low sulfur tailings can be compared, to provide the fundamental mineralogical input parameters for the development of a hydrogeochemical model, and to impose constraints on the multiple choices available for theoretical predictive modeling. The specific tasks undertaken to achieve these goals were: 1. qualitative and quantitative characterization of the starting materials in the low sulfur tailings (0.4 wt. % S), main tailings (1.0 wt. % S), and total tailings (2.5 wt. % S), 2. identification of the solid phases that are the primary source of acid and potential or known contaminants, 3. documentation of the evolution of oxidation of the sulfides in the tailings, specifically pyrrhotite, 4. identification of the secondary precipitates that serve to control the pore-water concentrations of dissolved ions and determination of the composition of the secondary precipitates, 5. identification of the solid phases that provide potentially acid-neutralizing capacity to the tailings, their alteration, and the resulting secondary products, 6. determination of the relative oxidation that has occurred between the low sulfur tailings (0.4 wt. % S), main tailings (1.0 wt. % S), and total tailings products (2.5 wt. % S), 7. and the determination of the relative oxidation that has occurred between the tailings in the field lysimeters and the tailings in the laboratory oxidation columns. The starting material, or primary mineralogy, is notably similar in all three tailings types, and is comprised predominantly of plagioclase feldspar, quartz, calcic amphiboles (primarily actinolitic 181 hornblende and actinolite), biotite, and chlorite, with lesser amounts of potassium feldspar, enstatite, augite, magnetite, ilmenite, and pyrrhotite, accessory pentlandite and chalcopyrite, and trace pyrite, apatite, and slag particles of various compositions. Quantitative electron probe microanalyses of the above minerals have been included in chapter 7; the compositions of the principal minerals in the tailings closely agree with those published by Hawley (1962). The relative abundance of each of these minerals varies only slightly from one tailings type to the other (appendix D). Pyrrhotite, which is the principal potential acid-generating mineral in all three tailings types, comprises approximately 1% of the low sulfur tailings, between 2 and 3% of the main tailings, and between 4 and 5% of the total tailings. Pentlandite, chalcopyrite and slag particles may contribute to acid generation at lower pH conditions, but are volumetrically of much less importance than pyrrhotite. Metals that can be mobilized in the acidic conditions produced by sulfide oxidation and that are of primary concern in the Copper Cliff tailings are nickel and copper, and potentially cobalt and chromium. In both the lysimeters and oxidation columns, the greatest source of nickel contamination is nickeliferous pyrrhotite, with lesser contributions from the oxidation of pentlandite and nickeliferous slag particles. Copper contamination in the lysimeters is predominantly a result of the oxidation of copper-rich slag particles, and to a lesser extent, chalcopyrite dissolution. However, in the oxidation columns, chalcopyrite dissolution is more prominent and is probably a greater source of copper than the slag particles. Cobalt in solution is likely derived from the oxidation of cobalt-rich pentlandite, and, to a lesser extent, from the oxidation of slag particles. The capacity for chromium contamination lies predominantly in the breakdown of chromium-rich slag; however, magnetite may also be a source of chromium if oxidation proceeds further. 182 The oxidation of pyrrhotite is characterized by numerous stages of pseudomorphic replacement by secondary oxidation products. Replacement begins by penetration along fractures, partings and grain boundaries, progresses to a stage in which only residual sulfides remain, and finally results in complete pseudomorphism. Pentlandite oxidation most commonly results in the formation of oxidation rims and, less often, in the development of a network-type replacement that produces a mottled appearance of the surface. The oxidation rate of pentlandite appears to be slower than that of pyrrhotite, but faster than that of chalcopyrite. Where chalcopyrite oxidation occurs, it most commonly results in dissolution textures such as embayed edges and etched fractures, and less frequently results in the precipitation of secondary covellite and iron oxyhydroxide rims. Rims of iron oxyhydroxides and individual grains of covellite commonly surround altered slag particles. The sulfide oxidation reactions frequently result in the precipitation of secondary phases that may serve to control pore-water concentrations of dissolved ions. For example, the multi-phase replacement of pyrrhotite, generally seen in the unsaturated zone of all three tailings types, consists predominantly of goethite, native sulfur, lepidocrocite, covellite, and occasionally indiscriminate iron sulfate. Goethite is also the dominant oxidation product associated with oxidized pentlandite, chalcopyrite, and slag particles in the unsaturated zone of the tailings, and is also locally associated with various minerals in the saturated zone. The goethite in the unsaturated zone of the tailings is notably depleted in nickel and cobalt with respect to the primary sulfide from which it is derived. Secondary goethite is also copper-poor compared to the original sulfides, but copper seems to be preferentially retained relative to nickel and cobalt. Goethite in the saturated zone of the tailings is interpreted to have precipitated from pore waters, and contains much higher Ni concentrations of up to 1.70 wt. % Ni; this goethite, therefore, is the principle repository of oxidation-derived nickel. Native sulfur is consistently devoid of metals. It commonly has been partially plucked from the polished thin sections, and is preserved best in grains where it is surrounded by another phase. Covellite is most abundant in the total tailings at the maximum depth of oxidation in a thin 183 accumulation zone, and provides a control on pore water concentrations of copper. Covellite is less abundant than goethite and native sulfur in the replacement of pyrrhotite, but is the dominant phase associated with the oxidation of slag particles. The presence of iron sulfates, identified in this study by interpretation of the multi-element x-ray maps, possibly will be verified when the tailings are re-examined after further oxidation. Jarosite and gypsum are minor constituents of the secondary oxidation products present in the Copper Cliff tailings. Both minerals were detected in the near-surface tailings, or those that have undergone the greatest degree of oxidation. The minerals are interpreted to have precipitated from sulfate- rich solutions resulting from sulfide oxidation, and somewhat serve to control the pore-water concentrations of Fe, K, Ca, and S0 4 . As well as providing possible "sinks" for dissolved ions, secondary minerals may inhibit the penetration of oxygen into the tailings by cementing the tailings minerals, as occurs in the pyrrhotite-rich column. These secondary cements are predominantly goethite, gypsum, and jarosite, and likely precipitated from solutions ladened with Fe, K, and S0 4 . The low sulfur tailings, main tailings, total tailings contain considerably lesser amounts of secondary cements. No carbonates were seen in the tailings and, therefore, there is no significant short term buffering capacity; however, silicate minerals can contribute to the long term acid neutralization. Two silicate minerals, namely plagioclase and biotite, in the Copper Cliff tailings exhibit alteration textures indicating dissolution reactions. These reactions, as outlined in equations 16, 17, 18, and 21 in section 1.2, consume acid and therefore contribute to the overall neutralization of the tailings. The dissolution of plagioclase produces a fine grained alteration rim and may release calcium into solution which can precipitate as secondary gypsum. Biotite alteration is recognized by a somewhat bleached colour and a reduction in 184 pleochroism. Dissolution of biotite liberates potassium that can be used to form jarosite, and as alteration progresses iron and magnesium are also released into solution. The result is the generation of a vermiculite-type clay mineral and progressive alteration to a cristobalite-type phase. Montmorillonite, which was detected in the x-ray diffractograms, may be the product of a similar dissolution reaction. The presence of montmorillonite has not been verified by other analytical methods. The estimatation of relative oxidation between tailings types was based on two factors: the maximum depth to which oxidation has occurred, and the degree or stage at which the majority of the sulfides present has been oxidized. Taking both of these criteria into account, oxidation is greatest in the total tailings, intermediate in the main tailings and least well developed in the low sulfur tailings. The relative degree of oxidation between the tailings in the field lysimeters and those in the laboratory oxidation columns was also determined. Oxidation has progressed further in the columns than in the lysimeters in that not only have more of the sulfides in each of the tailings types in the columns been altered, but the extent to which individual grains have been altered is greater in the columns. The difference between the total tailings and main tailings lysimeters and their corresponding columns is more pronounced than the difference seen between the tailings from the low sulfur tailings lysimeter and the low sulfur tailings oxidation column. A distinct difference in the oxidation style of the columns and lysimeters that may have significance with respect to the predictive capabilities of the two test types. Oxidation in the columns has resulted in the dissolution, or leaching of pyrrhotite, but there is no evidence of this in the lysimeters. Although this type of alteration is subordinate to the more typical pseudomorphic replacement, it suggests a smaller stored potential in the oxidation columns than in the field lysimeters. Stored potential is defined here as secondary metals stored in secondary oxidation products that can be re-released into solution if the redox conditions 185 change enough to solubilize the oxidation products. Therefore, the oxidation columns may give an accurate prediction of short term acid production and metal concentrations in leachate, but die field lysimeters might better predict the long term release of metals into solution. In conclusion, this thesis, which represents the fundamental mineralogical basis for the prediction of acidic drainage from the three tailings types, the low sulfur tailings (0.4 wt. % S), main tailings (1.0 wt. % S), and total tailings (2.5 wt. % S), will contribute to Inco's forthcoming decision regarding the utilization of the low sulfur tailings as a cover material. 186 9.0 R E F E R E N C E S Ahonen, L. and Tuovinen, O.H. (1994): Solid-Phase Alteration and Iron Transformation in Column Bioleaching of a Complex Sulfide Ore. In Environmental Geochemistry of Sulfide Oxidation (C.N. Alpers and D.W. Blowes, eds.), American Chemical Society, Symposium Series 550, pp. 79-89. Anders, G. and Mohide, T.P. (1980): The Nickel Industry and the Law of the Sea, Ontario Ministry of Natural Resources, Mineral Policy Background Paper Number 10, 28 pp. Avermann, M . (1994): Origin of the Polymict, Allochthonous Breccias of the Onaping Formation, Sudbury Structure, Ontario, Canada. In Large Meteorite Impacts and Planetary Evolution (B.O. Dressier R.A.F. , Grieve and V . L . Sharpton, eds.), Geological Society of America, Special Paper Number 293, pp. 265-274. Barlow, A.E . (1906): On the Origin and Relations of the Nickel and Copper Deposits of Sudbury, Ontario, Canada, Economic Geology, 1, pp. 454-466. Bateman, A . M . (1917): Magmatic Ore Deposits, Sudbury, Ontario, Economic Geology, 12, pp. 391-426. Bell, R. (1891): The Nickel and Copper Deposits of Sudbury District, Canada, Geological Society of America, Bulletin, 2, pp. 125-140. Bhatti, T . M . , Bigham, J.M., Vuorinen, A., and Tuovinen, O.H. (1994): Alteration of Mica and Feldspar Associated with Microbiological Oxidation of Pyrrhotite and Pyrite. In Environmental Geochemistry of Sulfide Oxidation (C.N. Alpers and D.W. Blowes, eds.), American Chemical Society, Symposium Series 550, pp. 91-105. Bierens de Harm, S. (1991): A Review of the Rate of Pyrite Oxidation in Aqueous Systems at Low Temperature, Earth-Science Reviews, 31, pp. 1-10. Blowes, D.W. and Jambor, J.L. (1990): The Pore-water Geochemistry and the Mineralogy of the Vadose Zone of Sulfide Tailings, Waite Amulet, Quebec, Canada. Applied Geochemistry, 5, pp. 327- 346. Blowes, D.W., Reardon, E.J., Jambor, J.L., and Cherry, J.A. (1991): The Formation and Potential Importance of Cemented Layers in Inactive Sulfide Mine Tailings. Geochimica et cosmochimica Acta, 55, pp. 965-978. Blowes, D.W., Al , T., Lortie, L., Gould, W.D. and Jambor, J.L. (1995a). Microbiological, Chemical and Mineralogical Characterization of Kidd Creek Mine Tailings Impoundment, Timmins Area, Ontario. Geomicrobiology Journal, 13, pp. 13-31. Blowes, D.W., Stuparyk, R.A., and Hanton-Fong, C.J. (1995b): New Approaches to the Prevention of Acid Mine Drainage. Energy, Mines and Resources Canada (CANMET) SSC file No. 0285Q.23440-4-1111, December, 1995. Card, K.D. (1978): Geology of the Sudbury-Manitoulin Area, Districts of Sudbury and Manitoulin. Ontario Geological Survey, Report 166, pp. 1-238. 187 Card, K.D. and Hutchinson, R.W. (1972): The Sudbury Structure: Its Regional Geological Setting. In New Developments in Sudbury Geology (J.V. Guy-Bray, ed.), Geological Association of Canada, Special Paper Number 10, pp. 67-78. Clark, A . M . (1993): Hey's Mineral Index. Chapman and Hall, New York, 852 pp. Coggans, C.J., Blowes, D.W., and Robertson, W.D. (1993): The Hydrology and Geochemistry of a Nickel Mine Tailings Impoundment, Copper Cliff, Ontario. In: Proceedings of the Second International Conference on the Abatement of Acidic Drainage, Montreal, PQ., September, 1991. M E N D , Ottawa, Ontario. Cohen, S.R. (1979). Environmental and Occupational Exposure to Copper. In Copper in the Environment (J.O. Nriagu, ed.), Environmental Science and Technology Series, pp. 1-16. Coleman, A.P. (1905): The Sudbury Nickel Region. Report of the Ontario Bureau of Mines, 1904, 14(3), pp. 1-183. Coleman, A.P., Moore, E.S. and Walker, T .L . (1929): The Sudbury Nickel Irruptive. Contributions to Canadian Mineralogy, pp. 1-54. Cowan, J.C. (1968): Geology of the Strathcona Ore Deposit. The Canadian Mining and Metallurgical Bulletin, 61, No. 699, pp. 38-54. Dickson, C.W. (1903): The Ore-Deposits of Sudbury. American Institute of Mining Engineers, Transactions, New York, 34, pp. 1-67. Dickson, C.W. (1904): The Mineralogy and Geology of the Sudbury, Ont., Copper-Nickel Deposits. Annals of the New York Academy of Sciences, New York, 15, 176 pp. Dietz, R.S. (1964): Sudbury Structure as an Astrobleme. Journal of Geology, 72, pp. 412-434. Doll R. (1958): Specific Industrial causes. In Carcinoma of the Lung (J.R. Bignall, ed.), Williams & Wilkins, Baltimore, pp. 45-59. Evangelou, V.P. and Zhang, Y .L . (1995): A Review: Pyrite Oxidation Mechanisms and Acid Mine Drainage Prevention. Critical Reviews in Environmental Science and Technology, 25(2), pp. 141-199. Fleischer, M . and Mandarino, J.A. (1995): Glossary of Mineral Species. The Mineralogical Record Inc., Tucson, 280 pp. Gasparrini, E. and Naldrett, A.J. (1972): Magnetite and Ilmenite in the Sudbury Nickel Irruptive. Economic Geolog\>, 67, pp. 605-621. Giblin, P.E. (1984): History of Exploration and Development, of Geological Studies and Development of Geological Concepts. In: The Geology and Ore Deposits of the Sudbury Structure. (E.G. Pye, A.J. Naldrett and P.E. Giblin, eds.), Ontario Geological Survey Special Volume 1, pp. 3-23. Hausinger, R.P. (1992): Biological Untilization of Nickel. In Nickel and Human Health: Current Perspectives. (E.Nieboer and J.O. Nriagu, eds.), John Wiley & Sons, Inc., pp. 21-36. 188 Hawley, J.E. (1962): The Sudbury Ores: Their Mineralogy and Origin. Canadian Mineralogist,!, pp. 1- 207. Hester, K.D. & Associates (1984). Practical Considerations of Pyrite Oxidation Control in Uranium Tailings. Research Report Prepared for National Uranium Tailings Program, Energy Mines and Resources Canada. (CANMET). Hey, M . H . (1954): A New Review of Chlorites. Mineralogical Magazine, 30, pp. 277-292. Hodson, P. V. , Borgmann, W. and Shear, H. (1979). Toxicity of Copper to Aquatic Biota. In Copper in the Environment (J.O. Nriagu ed.), Environmental Science and Technology Series, pp. 307-372. Howe, E. (1914): Petrographical Notes on the Sudbury Nickel Deposits. Economic Geology, 9, pp. 505- 522. Jambor, J.L. and Owens, D.R. (1993): Mineralogy of the Tailings Impoundment at the Former Cu-Ni Deposit of Nickel Rim Mines Ltd., Eastern Edge of the Sudbury Structure, Ontario. Energy, Mines, and Resources Canada (CANMET) division report M S L 94-4 (CF). Jambor, J.L. (1994): Mineralogy of Sulfide-rich Tailings and Their Oxidation Products. In: Environmental Geochemistry of Sulfide Mine-wastes (J.L. Jambor and D.W. Blowes, eds.), Mineralogical Association of Canada short course, May, 1994, 22, pp 59-102. Knight, C.W. (1917): Geology of the Sudbury Area and Description of Sudbury Ore Bodies. Report of the Royal Ontario Nickel Commission, pp. 104-211. Leake, B.E. (1978). Nomenclature of Amphiboles. American Mineralogist, 63, pp. 1023-1052. Lochhead, D.R. (1955): A Review of the Falconbridge Ore Deposit. Economic Geology, 50, pp. 42-50. Lumb, G. and Sunderman, F.W. (1988): The Mechanism of Malignant Tumor Induction by Nickel Subsulfide Annual Clinical Laboratory Science, 18, pp. 353-366. Michener, C.E. and Yates, A.B. (1944): Oxidation of Primary Nickel Sulphides. Economic Geology and the Bulletin of the Society of Economic Geologists, 39(7), pp. 506-514. Mond, L., Langer, C. and Imiche, F. (1890): The Action of Carbon Monoxide on Nickel. Journal of the Chemical Society of London, 57, pp. 749-753. Morimoto, M . (1988): Nomenclature of Pyroxenes. Mineralogical Magazine, 52, pp. 535-550. Morin, K.A. and Cherry, J.A. (1986). Trace Amounts of Siderite near a Uranium Tailings Impoundment Elliot Lake, Ontario, and its Implication in Controlling Contaminant Migration in a Sand Aquifer. Chemical Geology, 56, pp. 117-134. Moses, C O . , Nordstrom, D.K., Herman, J.S. and Mills, A .L . (1987): Aqueous Pyrite Oxidation by Dissolved Owygen and by Ferric Iron. Geochimica et Cosmochimica Acta, 51, pp. 1561-1571. Munsell Color Company, Inc. (1971): Munsell® Soil Color Charts. Munsell Color Company, Inc., Baltimore, Maryland 21218, U.S.A., 1971 edition. 189 Naldrett, A.J. and Kullerud, G. (1967): A Study of the Strathcona Mine and Its Bearing on the Origin of the Nickel-Copper Ores of the Sudbury District, Ontario. Jounal of Petrology, 8(3), pp. 453-531. Naldrett, A.J., Hewins, R.H., Dressier, Burkhard 0. and Rao, B.V. (1984): The Contact Sublayer of the Sudbury Igneous Complex. In: The Geology and Ore Deposits of the Sudbury Structure. OGS special volume 1, pp. 253-274. Nickel, E .H. and Nichols, M.C. (1991): Mineral Reference Manual. Van Nostrand Reinhold, New York, 250 pp. Nicholson, R.V. and Scharer, J .M. (1994): Laboratory Studies of Pyrrhotite Oxidation Kinetics. In: Environmental Geochemistry ofSidfide Oxidation (C.N. Alpers and D.W. Blowes eds.), American Chemical Society, Symposium Series 550, pp. 14-30. Nolan, Davis & Associates (1987). Study of Acid Waste Rock Management at Canadian Base Metal Mines. Energy, Mines and Resources Canada (CANMET) DSS No. 23317-6-1738/01-SQ. Owen, C.A., Jr. (1981): Copper Deficiency and Toxicity: Acquired and Inherited, in Plants, Animals, and Man. Copper in Biology and Medicine Series, Noyes Publications, New Jersey, pp. 65-146. Pattison, E.F. (1979): The Sudbury Sublayer. Canadian Mineralogist, 17, pp. 257-274. Peredery, W.V. (1972): Chemistry of Fluidal Glasses and Melt Bodies in the Onaping Formation. In: New Developments in Sudbury Geology (J.V. Guy-Bray, ed.), Geological Association of Canada, Special Paper Number 10, pp. 49-59. Petruk, W. (1989): The MP-SEM-IPS Image Analysis System. In: Image Analysis Applied to Mineral and Earth Sciences, Mineralogical Association of Canada, short course, Ottawa, May 1989, pp. 37-42. Phemister,T.C. (1926): Igneous Rocks of Sudbury and Their Relation to the Ore Deposits. Ontario Department of Mines, Annual Report, 34, pp. 1-61. Pierard, G.E. (1979). Toxic Effects of Metals from the Environment on Hair Growth and Structure. Journal of Cutaneous Pathology, 6, pp. 237-242. Pratt, A.R., Nesbitt, H.W. and Muir, I.J. (1994): Generation of Acids from Mine Waste: Oxidative Leaching of Pyrrhotite in Dilute H 2 S 0 4 Solutions at pH 3.0. Geochimica et Cosmochimica Acta, 58, pp. 5147-5159. Puro, M.J., Kipkie, W.B., Knapp, R.A., McDonald, T.J. and Stuparyk, R.A. (1995): Inco's Copper Cliff Tailings Area. In: Sudbury '95: Mining and the Environment, Conference Proceedings. (T.P. Hynes and M . C . Blanchette, eds.), C A N M E T , Ottawa, Ontario, 1, pp. 181-191. Reardon, E.J. and Moddle, P.M. (1985): Gas Diffusion Coefficient Measurement on Uranium Mill Tailings: Implications to Cover Layer Design. Uranium, 2, pp. 111-131. Ritchie, A.I. M . (1994). The Waste-rock Environment. In: Environmental Geochemistry of Sulfide Mine- wastes (J.L. Jambor and D.W. Blowes, eds.), Mineralogical Association of Canada short course, May, 1994, 22, pp 133-161. 190 Ritchie, A.I .M. and Harries, J.R. (1987). The Effect of Rehabilitation on the Rate of Oxidation of Pyrite in a Marine Waste Rock Dump, Environmental Geochemistry and Health, 9(2), pp. 27-36. Robertson, A. MacG (1987). Alternative Acid Mine Drainage Abatement Measures. Province of British Columbia, Mine Reclamation Symposium Focus on Acid Mine Drainage Campbell River, B.C. April. Scribbins, B.T., Rae, D.R., and Naldrett, A.J. (1984): Mafic and Ultramafic Inclusions in the Sublayer of the Sudbury Igneous Complex. Canadian Mineralogist, 22, pp. 67-75. Sherlock, E.J., Lawrence, R.W. and Poulin, R. (1995): On the Neutralization of Acid Rock Drainage by Carbonate and Silicate Minerals. Environmental Geology, 25, pp. 43-54. Sorenson, J.R.J. (1979). Therapeutic Uses of Copper. In: Copper in the Environment (J.O. Nriagu, ed.), Environmental Science and Technology Series, pp. 83-162. Souch, B.E. and Podolsky, T. (1969): The Sulfide Ores of Sudbury: Their Particular Relationship to a Distinctive Inclusion-Bearing Facies of the Nickel Irruptive. In: Magmatic Ore Deposits, Economic Geology Monograph 4, pp. 252-261. Steffen, Robertson and Kirsten (B.C.) Inc. (1989). British Columbia Acid Mine Drainage Task Force Report, Draft Technical Guide, 1 pp. 6-9, 6-12. Stevenson, J.S. and Colgrove, G.L. (1968): The Sudbury Irruptive: Some Petrogenetic Concepts Based on Recent Field Work. Report of 23rd International Geological Congress, Czechoslovakia, 5(4), pp. 27-35. Stichbury, M . , Bechard, G. , Lortie, L. and Gould, W.D. (1995). Use of Iiihibitors to Prevent Acid Mine Drainage. In: Sudbury '95: Mining and the Environment, Conference Proceedings. (T.P. Hynes and M.C. Blanchette, eds.), C A N M E T , Ottawa, Ontario, 2, pp. 613-622. Stoffler, D., Deutsch, A., Avermann, M . , Bischoff, L., Brockmeyer, P., Buhl, D., Lakomy, R., and Miiller- Mohr, V. (1994): The Formation of the Sudbury Structure, Canada: Toward a Unified Impact Model. In: Large Meteorite Impacts and Planetary Evolution (B.O. Dressier R.A.F. Grieve and V . L . Sharpton, eds.), Geological Society of America, Special Paper Number 293, pp. 303-318. Stuparyk, R.A., Kipkie, W.B., Kerr, A.N. and Blowes, D.W. (1995): Production and Evalutaion of Low Sulphur Tailings at INCO's Clarabelle Mill. In: Sudbury '95: Mining and the Environment, Conference Proceedings. (T.P. Hynes and M . C . Blanchette, eds.), C A N M E T , Ottawa, Ontario, 1, pp. 159-169. Sunderman, F. W. (1992): Hazards From Exposure To Nickel: A Historical Account. In: Nickel and Human Health: Current Perspectives. (E. Nieboer and J.O. Nriagu, eds.), John Wiley & Sons, Inc., pp. 1-20. Thode, H.G. , Dunfore, H.B. and Shima, M . (1962): Sulfur Isotope Abundances in Rocks of the Sudbury District and Their Geological Significance. Economic Geology, 57, pp. 565-578. Thomson, J.E. (1969): A Discussion of Sudbury Geology and Sulphide Deposits, Ontario Department of Mines, Miscellaneous Paper 30, pp. 1-22. 191 Walsh, F. and Mitchell, R. (1972): A pH Dependent Succession of Iron Bacteria. Environmental Science and Technology, 6(9), pp. 809-812. Wandke, A. and Hoffman, R. (1924): A Study of the Sudbury Ore Deposits. Economic Geology, 19, pp. 169-204. Watzlaf, G.R. (1986). Control of Acid Drainage from Mine Wastes Using Bacterial Inhibitors. Proceedings of the 1986 National Meeting of the American Society of Surface Mining and Reclamation, Jackson, Mississippi, March 17-20. Williams, G.H. (1957): Glowing Avalanche Deposits of the Sudbury Basin. Ontario Department of Mines, Annual Report, 65(3), pp. 57-89. Yates, A.B. (1948): Properties of International Nickel Company of Canada. In: Structural Geology of Canadian Ore Deposits, Jubilee Volume, Canadian Institute of Mining and Metallurgy, pp., 596- 617. 192 Appendix A Mining History and Geological History of the Sudbury Igneous Complex. 193 A . l The Geological History of the Sudbury Area A.J.J Exploration and development In 1856, a man named Salter was running a survey line for the government through the Sudbury area to divide Northern Ontario from the rest of the province. He noticed a considerable magnetic attraction and a large degree of iron in the rocks, and reported his findings to Alexander Murray of the Geological Survey of Canada. Murray sampled the site and discovered that the rock had very high concentrations of copper and nickel, but due to the remoteness and inaccessibility of the area at the time, his report attracted little interest. This original occurrence is only 200 m or so from where the Creighton open pit mine is today. The development of this occurrence and the many Ni-Cu deposits in the area didn't occur until construction of the Canadian Pacific Railway in 1883. Giblin (1984), and references therein, present a chronological account of the history of the Sudbury area. This brief overview of Sudbury's geological history given here is taken from Giblin's paper, but is by no means inclusive of all the work done in the area. Building the railroad called for forests to be cleared, revealing a surprising amount of gossan, and the cutting of rock to lay the railroad tracks led to the exposure of high-grade mineralization. This occurrence was acquired by T. Murray and, once developed, became the Murray mine. Most of the currently known orebodies in the area today were discovered by prospectors who flocked to Sudbury in search of the easily recognizable gossans in the few years following Murray's discovery. 194 The Canadian Copper Company was quickly established in Sudbury. It was the company to first produce Sudburian ore, and did so at the Copper Cliff mine in 1886. The same company built Sudbury's first smelter which began operating in 1888. Initially, Sudbury ore was believed to be valuable on account of its high copper contents, but proved unusually difficult to treat. It wasn't until assays of the furnace products revealed high nickel content, now Sudbury's claim to fame, nearly 4 years after the first discoveries of ore were made. Finding a market for this metal was a challenge and a problem for these companies. The total annual world consumption of nickel in the late 1880s was only 1000 tonnes. The nickel market at this time was dominated by New Caledonia. S.J. Ritchie, president of the Canadian Copper Company set out to find a larger market for nickel and did so by convincing the United States Navy to test nickel steel for use in armor plating. The tests were successful and in 1891, the U.S. Government appropriated $1,000,000 to purchase Sudbury nickel matte to be used in the production of nickel steel for armor plating. This order succeeded in getting the development in the Sudbury area off its feet and Sudbury on its way to becoming a leading mining centre. In 1902 the International Nickel Company of Canada was formed which effectively merged most of the principal mining, smelting and refining companies in the area, including the Canadian Copper Company. The International Nickel Company of Canada played an important role in developing new alloys and uses for nickel to expand their market. Numerous mining companies who have left their marks on the Sudbury landscape; examples are, the Mond Nickel Company, Limited, which operated from 1900 to 1929 when it merged with the International Nickel Company of Canada, and the British American Nickel Corporation, which from 1912 to 1924 was a successful Sudburian mining and smelting company. In 1928, a new company was formed, Falconbridge Nickel Mines Limited (shortened to Falconbridge Limited 195 in 1982). Together, Falconbridge Limited and the International Nickel Company of Canada Limited, the latter referred to as Inco Limited since 1976, have dominated mining in Sudbury since the 1930s. Sudbury, home of the Big Nickel, yields several other commodities. As mentioned previously, the original interest in Sudbury ore was based on its copper content. There are approximately equal amounts of copper and nickel in the Sudbury area. For many years, Inco Limited was Canada's largest single producer of newly mined copper. Sudbury was also for many years the world's leading producer of newly mined platinum group metals such as platinum, palladium, iridium, osmium, rhodium and ruthenium. Other commodities include gold, silver, cobalt, selenium, tellurium, and sulfur, as well as iron ore pellets that were produced in the past. In just over a century, since the first major discovery of nickel in the Sudbury area, the city has grown from a small railway construction and lumbering village with a population of about 300, to a modern metropolitan centre with a population of approximately 145,000. The mining industry in the city has provided employment for many thousand Sudburians as well as provided industrial raw materials and wealth for Canadians. Because Canadian industries consume only a small percentage of the nickel that can be produced, most of the nickel is exported and is an important source of foreign exchange earnings. Following World War II, growing competition from foreign producers reduced Sudbury's share of the world's nickel market from 80% to about 18%. Although this appears to be a major decline, for most of this period the tonnage of nickel produced rose as the total market grew. Foreign competition and the recession in the early 1980s had an adverse affect on the nickel industry. However, the ore reserves in 196 Sudbury are such that there is no geological reason to fear that Ontario nickel production will not continue long into the next century (Anders and Mohide, 1980). A.J. 2 The geological debate Sudbury is an area famous both for economical and geological reasons. A tremendous amount of research has been done in the area attempting to sort out its complex and unique geological history. Despite, or maybe because of, the large volume of work done in the area, many problems and controversies have arisen over the years, not the least of which focuses on the formation of the ores themselves. The 1.85 Ga Sudbury structure is located 400 km north of Toronto, Ontario at the boundary between the Superior Province and the Southern Province in the Canadian Shield (Avermann, 1994). The sulfide deposits that are host to the nickel, copper, platinum group metals, and other metals are associated with a large igneous body, the Sudbury Igneous Complex. The complex has been referred to in past years as the Nickel-Bearing Eruptive, the Sudbury Irruptive and the Nickel Irruptive. The intrusion is an elliptical ring with a 60 km long major axis striking northeast, and a minor axis 27 km long. It is divided into three main rings: the outer ring is norite, which grades into the transition zone of gabbro to the inner ring of granophyre. The basin generally dips inwards at between 30° and 50° toward the centre, but may locally dip more steeply and in the opposite direction. The ore deposits are generally found around the outer, lower edge of the norite in a quartz diorite sublayer, and in dike-like bodies, termed "offsets", that either radiate outward from the base of the norite, or occur in the footwall rocks parallel to the main complex. There are three main hypotheses as to the relationship between the ore deposits and the norite unit. These are: 197 1. The ores formed as a result of magmatic segregation in which the sulfides were present as liquids in the main body of magma, and during crystallization settled under the influence of gravity to the base of the norite. This hypothesis was the first to be suggested by Bell (1891) and was supported by Coleman (1905), Barlow (1906), Coleman et al. (1929), and Stevenson and Colgrove (1968) among others. 2. Dickson (1903) suggested that the sulfides were introduced by hydrothermal fluids. His hypothesis was strongly supported by Knight (1917), Wandke and Hoffman (1924) and Phemister (1926). 3. The third theory, that the sulfides were introduced as an immiscible sulfide liquid suspended in the silicate magma of separate, perhaps younger, noritic intrusions, was proposed by Howe (1914) and supported by scientists such as Bateman (1917), Lochhead (1955) and Naldrett and Kullerud (1967). Yates (1948), in trying to understand the localization of the ores, classified the ore deposits into three major types: a disseminated ore confined almost entirely to the quartz diorite; massive sulfide ore occurring in almost any rock type, but usually along definite fault or breccia zones; and stringer ore consisting of massive sulfide stringers occurring in a wide variety of brecciated country rocks. He suggested the ores were partly of hydrothermal replacement origin, and partly of deep-seated contact metamorphic origin. At this point, the quartz diorite was recognized as being a distinct unit from the norite, but genetically related. Yates pointed out that most of the ore occurs in the quartz diorite, and that there is little ore, massive or disseminated, in the true norite. Souch and Podolsky (1969) referred to the quartz diorite sublayer as a sulfide- and inclusion-bearing noritic unit occurring at intervals below the norite. 198 Radiometric dating done by the same authors suggested that the true norite and the ore-bearing sublayer are contemporaneous and both are older than the granophyre unit. This sublayer was further described in 1979 by Pattison. He proposed two theories as to its formation, both involving the meteorite impact theory, which will be discussed later. The first involved segregation of a sulfide-rich magmatic differentiate, formed in the lower levels of an impact-triggered magma, the segregated fraction then being injected along the unconformity between footwall rocks and the overlying Onaping Formation. A second intrusive phase followed and crystallized to form the norite- granophyre mass. According to this hypothesis, meteorite impact served only as a triggering mechanism for relatively conventional magrhatic processes. The second and preferred hypothesis suggested that the igneous sublayer was a mixture of sulfide-rich impact melt and brecciated mafic to ultramafic footwall rocks derived from the deeper levels of the crater structure, which was emplaced along the walls of the crater. It was suggested that the sulfides were derived from previous concentrations in mafic to ultramafic magmatic country rocks. As in the previous case, intrusion of the main mass of the Sudbury Igneous Complex then followed. Lochhead (1955) suggested that the sulfides were deposited from ascending solutions, which also altered part of the main mass of the norite to produce the quartz diorite. A similar theory, based on extensive experimental work to model the sulfide formation in the Sudbury area, was suggested by Naldrett and Kullerud in 1967. It was proposed that the sulfur present in the ores was derived from an external source, moved into the intrusion, and reacted with it to form the nickel and copper sulfides. They believed the complex was a funnel-shaped body of magma, which then cooled and differentiated, giving rise to a fractionated sequence ranging in composition from dunite to felsic norite. This was believed to have been followed by intrusion of mafic norite magma carrying some sulfide 199 liquid in suspension, by brecciation of mafic and ultramafic material at depth within the Complex, and then by intrusion of xenolithic norite magma which carried droplets of liquid sulfide in suspension. The xenoliths and the sulfides settled toward the base of the intrusion, with some sulfides penetrating the footwall rocks beyond the intrusion and some remaining trapped in the intrusion. Sulfide crystallization was interpreted to have been followed by brecciation and crushing along the contact between the Sudbury Igneous Complex and the footwall gneiss, giving rise to the footwall breccia and main-zone ore. In 1968, they went on to suggest that the sulfides were carried up from depth as droplets of immiscible sulfide-oxide liquid suspended in the silicate magma of the xenolithic norite. Hawley (1962) proposed yet another theory regarding the quartz diorite unit which is so infamously associated with the ore. He suggested that it formed from a more basic parent by either assimilation of acidic wallrock fragments, or through acquisition of silica and volatiles acquired with the sulfide ores. It has been more than just the ore-bearing rocks that have attracted the attention of scientists to the Sudbury area. Much discussion has also been focused on the shape and character of the Sudbury Igneous Complex itself, the nature and origin of the unusual rocks of the Sudbury Breccia, and on the Onaping Formation. Generally, there has been an ongoing debate regarding the origin of the Sudbury Structure, a catch-all term referring to the Sudbury Igneous Complex, nearby rocks and associated structural features. The rather unique breccia that is pervasive in the Sudbury area occurs in a zone many kilometers wide, irregularly diffused throughout all the rocks surrounding, and older than the Sudbury Igneous Complex. The breccia is assumed to be younger than the rocks surrounding the Complex but older than the Sudbury Igneous Complex itself. It is generally agreed to that the Sudbury Breccia is related to the 200 sequence of events responsible for forming the Sudbury Structure, intrusion of the Sudbury Igneous Complex and ultimately the formation of the ores. The main debate surrounding the Sudbury story is to what exactly is the sequence of events. There are two main arguments. One is the origin through the action of explosive high-pressure fluids related to volcanism or diatremes, and the other supports the theory of a sudden severe compression generated by meteorite impact. Prior to 1964, it was generally agreed to that the Sudbury Igneous Complex was funnel-shaped and most likely associated with ultramafic rocks at depth. Evidence to support this theory was widespread. For instance, Thode et al. (1962) showed that the sulfur isotopic for the Sudbury Igneous Complex and related ores are consistent with the gravity-controlled differentiation from a single sheet like body of magma, a theory popularized by Coleman et al. in 1929. However, a turning point occurred when Dietz (1964) published a paper that shook the Sudbury landscape. He suggested the Sudbury Structure was an astrobleme, whose formation was initiated by the impact of a large copper-rich, nickel-iron meteorite in the middle Precambrian. His paper suggested that a meteorite struck earth at Sudbury, exploded, and excavated a shallow crater about 45 kilometres across and kilometres deep; that shock waves spread outward causing severe brecciation in the country rocks, giving rise to the Sudbury Breccia and forming shatter cones in the wall rocks of the crater. He further suggested that the ores were splash-emplaced material from the meteorite, and that the quartz diorite represented impact-liquefied country rock. It was proposed that fracturing of the crust and heat resulting from the impact resulted in generation of magma in the deep crust, which welled up into the crater, cooled and differentiated to form the norite-granophyre complex. 201 Dietz's paper renewed interest in Sudbury geology worldwide. He had many supporters as well as adversaries regarding his theory. The point of question in the whole story seemed to hinge on the controversial Onaping Formation. The Onaping Formation consists of a thick sequence of predominantly pyroclastic rocks and occurs only within the Sudbury Basin, where it overlies, and is intruded by, granophyre of the Sudbury Igneous Complex. Williams (1957) and Thomson (1969) concluded that this formation represents a vast accumulation of rapidly deposited glowing avalanches in a basin located approximately on the site of the present Sudbury Basin. The glowing avalanches were propsed to have discharged through fissures located near the present inner margin of granophyre, and the fissures coincided with channelways through which rhyolite dikes had earlier been intruded. It was suggested that the rapid discharge of more than 480 km3 of avalanche debris caused sufficient drainage of the magma reservoirs to cause further sinking of the basin, forming a deep volcano-tectonic sink. The injection of the norite and granophyre, as successive injections, was postulated to have then occurred along ring faults surrounding the basin. The Sudbury Igneous Complex was therefore considered to have the form of a ring-dike. Dietz believed that the Onaping Formation formed through explosive degassing of the crustal zone of the cooling magma. Peredery (1972) supported Dietz by concluding that the Onaping Formation formed as a consequence of meteorite impact, consisting of a basal breccia, an overlying grey Onaping, the uppermost black Onaping and melt rocks. He interpreted the basal breccia as the earliest fall-back material, the grey Onaping as the true fall-back breccia, the finer grained black Onaping as a wash-in deposit derived from the fall-back brought in by a tsunami-like wave, and the melt rocks as products of fusion of pre-existing country rocks. Peredry also examined many of the glasses found in the basin and pointed out that the glasses are anomalous in composition, and that the compositional distribution field is unlike that found at a conventional volcano. 202 Not everyone was convinced that Sudbury was an astrobleme impact scar. Card and Hutchinson (1972), for example, believe the evidence, such as the junction of 3 structural provinces and 2 main fault systems, suggests that the Sudbury Igneous Complex lies within a possible major Precambrian rift system, and that the complex is only one of a series of varied mafic intrusions, many with associated Ni and Cu mineralization. In 1978, Card reviewed the arguments for and against impact. His view is summarized as follows (Card 1978): Evidence for a meteorite impact includes the following: the probable original circular shape of the structure; the nature of the Onaping Formation which is similar to suevite breccias of known meteorite impact sites, the abundant Sudbury breccias and shatter cones; and the microscopic evidence for shock metamorphism. Arguments against a meteorite impact origin include the following: the relationships of the Sudbury Structure to major tectonic elements such as the Grenville Front; to major structures, such as faults of the Murray and Onaping Systems; to magnetic-gravity anomalies indicative of larger scale crustal peculiarities; to pronounced facies variations in the adjacent Ajuonian rocks; and to regional orogenic events. These relationships indicate that the Sudbury Structure is an integral part of its regional setting in space and time, and is not simply the product of fortuitous meteorite impact at this particular site. In the last few years, there has been another movement in support of the astrobleme theory, as originally suggested by Dietz. Evidence such as Nd and Sr isotope ratios, and the presence of pseudotachylytes and shatter cones have been interpreted as resulting from a massive compressive and decompressive event such as a meteorite impact. Scientists who have rekindled this theory have developed a unified impact model (Stoffler et al., 1994). This model suggests that the structure is the erosional remnant of a tectonically deformed and metamorphosed ring-shaped impact basin with an original rim diameter of 220 km. The ores were thought to have been produced by impact melting of the upper and lower crust and subsequent differentiation of the melt. There has been geological and academic work done in the Sudbury Igneous Complex for more a century, and it is not likely to cease soon. Included in the future work is the extensive environmental assessment and monitoring studies being undertaken by the companies mining in the Sudbury district. Appendix B Some Interesting Facts about Nickel and Copper: the two metals of primary concern in the Copper Cliff tailings. 205 B. l Nickel B.l.l The history of nickel In the seventeenth century, German miners in Schneeberg found a red-coloured ore that they believed to be copper-bearing. They misnamed the ore Kupfer-nickel (copper-nickel). However, it contained no copper, and was later identified as nickel arsenide (NiAs). These Kupfer-nickel ores resulted in the recognition of the hazards associated with nickel, especially on the lungs of the German workers. It seems that after these hazards were acknowledged, Nickel, meaning scamp in German, joined the ranks of Kobalt, which in German denotes a goblin. These evil spirits (Kobalt and Nickel) were believed to haunt the mines and do harm to the miners. During this time in the mining districts in Germany, church services included prayers for the protection of miners from Kobalt and Kupfer-nickel. It was 1754 when nickel was officially recognized as an element and named by Axel Frederik Cronstedt. It was first isolated as the metal in 1820 by a man named Berthier; this brought about a worldwide search for nickel-containing ores. Joseph Wharton was successful in producing malleable nickel in 1865 in Philadelphia, Pennsylvania. That same year, nickel was used in making US coinage, specifically a 3-cent coin containing 75% nickel and 25% copper. B.l.2 Nickel toxicity In 1890, Mond and his co-workers (Mond et al., 1890) discovered that the physical and chemical properties of nickel carbonyl were especially useful in separating nickel from its ores. In 1903, the first 206 two workmen to die from exposure to nickel carbonyl were reported; they had worked in the Mond Nickel Works at Clydach, Wales. Soon after, the toxicity of nickel carbonyl was well known. Although nickel in the form of nickel carbonyl was known to be hazardous, prior to World War II, nickel salts were used medicinally for treatment of epilepsy, chorea, migraine and neuralgia. WW II sparked much research into the toxicity of nickel, particularly in those people dealing with nuclear energy who were at risk of exposure to nickel tetracarbonyl [Ni(C04)]. After the war, it was recognized that in addition to nickel carbonyl, exposure to nickel and other nickel compounds may be deleterious to health, and medicinal practices involving nickel were abandoned. The high incidence of pulmonary cancer occurring in nickel workers was first recognized by Baader in 1937. During the period between 1948 and 1956, Doll (1958) using coronary reports estimated that the number of nickel workers dying of cancer of the nose was 150 times normal and cancer of the lung was five times the norm. Lumb and Sunderman (1988) hypothesized that carcinogenic potency is inversely related to the solubilities of nickel compounds in water. The carcinogenic compounds that are sparingly soluble in water at 37°C include nickel dust, nickel sulfide, nickel carbonate, nickel oxide, nickel carbonyl and Ni(II)bisdimethylglyoxime. However, although nickel can be toxic it is an essential trace element for plants and animals and is ubiquitous on Earth. B.l.3 Nickel's role in everyday life In many plants, nickel is a micronutrient needed for the enzyme activity of urease and hydrogenase. Without these enzymes, accumulation of toxins in the plant's urea may cause plant necrosis, or a decrease in the efficiency of symbiotic nitrogen fixation may result in slower plant growth. The role of nickel in animals is less well understood than in plants; however, it has been documented that in rats and chickens 207 nickel deficiency leads to impaired liver metabolism and morphology. Even less understood than that is the role of nickel in microorganisms, except that it seems to be a functional requirement for growth, perhaps with a direct connection to hydrogen metabolism (Hausinger, 1992). B.2 Copper B. 2.1 The history of copper Copper was found by Neolithic man, who adorned himself with ornaments made of this shiny metal. It was first mined as a metal in Cyprus as early as 8000 B.C., at which place the metal was named copper, after the Late Latin term Cuprum. Copper was considered to be sacred to Aphrodite, the Greek goddess of love and beauty, and later by Ramses III and King Solomen. Although copper's early worth was predominantly based on its ornamental value, it later found a niche in the realm of medicine. As early as 3000 B.C., the Egyptians used copper both as an antiseptic for healing wounds and in the sterilization process of their drinking water. Folklore also has it that copper bracelets used to be worn to cure arthritis in many cultures (Sorenson, 1979). It has also been used medicinally to treat granulomatous inflammations of the eye, epilepsy and back pain (Owen, 1981). At some point, man learned to alloy copper, the first alloy being a combination of copper with tin to produce bronze, a metal prized for its use in weaponry because of its hardness. Since the invention of bronze, there have been many copper alloys, for instance brass, bell metal, gun metal, German silver, aluminum-bronze, phosphor-bronze, manganese-bronze, silicon-bronze, and beryllium-copper. Copper is utilized primarily for its malleability, electrical and heat conductivity and resistance to corrosion. It is used in castings, sheets, rods, tubing, wire, gas and water piping, roofing materials, cooking utensils, chemical 208 and pharmaceutical equipment and coins. Copper compounds are also found in many insecticides, fungicides, algaecides and moluscicides (Cohen, 1979). B. 2.2 Copper toxicity Copper toxicity has been documented for nearly 200 years. In France during the mid-1800s, copper sulfate was a well known and popular murder weapon and abortifacient, and in India, the same copper compound was used for suicidal purposes. The people most susceptible to copper poisoning were people who worked in copper smelters and brass foundries as well as vineyard sprayers using a copper sulfate fungicide. Many terms were derived from these people for copper toxicity, including "copper fever", "Brass founders' ague", "Monday fever", "the smothers", and "metal fume fever". Symptoms of subtle copper poisoning are nausea, vomiting, headaches, bronzing of the skin, and a greenish discolouration of disinterred hair, teeth and other bones. If poisoning is severe enough, symptoms such as necrosis, bile thromb, fibrosis, idiopathic portal hypertension, angiosarcoma, eczematous dermatitis, renal failure, diarrhea and acrodynia (or pink disease) may occur. Even more serious, and possibly fatal, may be the development of Wilson's disease (hepatolenticular degeneration), cardiovascular disease, lymphatic cancer, hepatic cirrhosis, leukemia and cancers of the lung, intestine, prostate, breast and skin (Owen, 1981). As a point of interest, copper poisoning associated with food or drink is related to the copperware it is cooked in rather than to the food or fluid directly. Food cooked in copper vessels loses its vitamin C content. Tap water's copper concentration increases only if the pH of the water is low, and the copper 209 then comes from copper pipes used to transport the water rather than directly from the water source itself (Pierard, 1979). Copper in water, however, may be exceedingly toxic to aquatic biota; concentrations as low as 5 to 25 u.g/L are lethal to some invertebrate and fish species. The toxicity seems to be related to the nature of the body covering; the higher sensitivity of the smaller or younger aquatic individuals may be related to a higher surface:volume ratio (Hodson et al., 1979). B. 2.3 Copper's role in everyday life As with most metals, too little or too much copper is harmful. Copper is essential to life, and without copper, plants become pale and bear little fruit or grain. Copper deficient animals are prone to altered blood, bone and arteries because without enough copper, the mobilization of stored iron is prevented. Humans lacking essential copper may develop Menke's steely-hair disease, or the inability to pass copper normally through their cells. However, copper deficiency is rare in humans; the dietary content of an average Western diet is between 2 and 5 mg Cu/day, and symptoms of copper toxicity begin when 7 mg Cu/day or more are ingested (Cohen. 1979). 210 Appendix C : Megascopic Characterization of the Field Lysimeter and Laboratory Column Tailings. 211 C . l Field Lysimeter Test Pit Samples C.l.l LST-1: low sulfur tailings (0.4 wt. % S), tailings surface was dry when sampled. The core from the low sulfur tailings lysimeter, taken where the surface of the tailings was dry, was relatively homogenous with respect to colour and grain size. The tailings were various shades of grey and sand size (between 1/16 and 2 mm in diameter), with thin intermittent zones of silt size grains. These zones were slightly more brown and more easily deformed by coring than the coarser material. The core was 86 cm in length and relatively noncohesive. Colours were indexed using Munsell's soil colour chart and are given in table C - l below. T O P D E P T H C O L O U R M U N S E L L (cm) N O T A T I O N * 0-15 dark grey 7.5YR 4/0 15-35 mottled grey and pale yellow 7.5YR 6/0 and 5Y 7/3 35-63 dark grey 7.5YR 4/0 63-65 light brownish grey 2.5YR 6/2 65-70 dark grey 7.5YR 4/0 70-78 light brownish grey 2.5YR 6/2 78-86 dark grey 7.5YR 4/0 0 cm * Munsell notation is described in section C.3. Table C - l : Depth profile of the Munsell soil colour assignments in the low sulfur tailings lysimeter, core #1. 86 cm 7.5YR4/0 dark grey 7.5YR6/0 + 5Y7/3 mottled grey + pale yellow 7.5YR4/0 dark grey 2.5YR6/2 light brownish grey 7.5YR4/0 dark grey 2.5YR6/2 light brownish grey x7.5YR4/0 dark grey LST-1 B O T T O M C.l.2 LST-2: low sulfur tailings (0.4 wt. % S), tailings surface was wet when sampled. The tailings in this core are relatively homogenous with respect to colour, but heterogeneous in grain size. In general, the tailings are finer grained than LST-1, and the coarser areas are greyer in colour than the finer grained zones, the latter of which are comparatively browner. Thin beds, approximately 1 to 2 cm thick, of fine grained material are present in the top half of the core. In the bottom half, however, the 212 tailings are predominantly of silt size. The total length of this core is 85 cm, and the core has been colour indexed with respect to depth (table C-2). TOP DEPTH COLOUR MUNSELL (CM) NOTATION 0-5 grey 10YR6/1 5-10 grey 2.5Y 5/0 10-11 pale yellow 5Y 7/3 11-16 grey 2.5Y 5/0 16-17 pale yellow 5Y 7/3 17-20 grey 2.5Y 5/0 20-45 grey 10YR6/1 45-66 dark olive grey 5Y 3/2 66-85 grey 10YR6/1 0 cm 10YR6/1 grey /2.5Y5/0 grey -5Y7/3 pale yellow , ^2.5Y5/0 grey \5Y7/3 pale yellow 2.5Y5/0 grey 10YR6/1 grey 5Y3/2 dark olive grey 10YR6/1 grey 85 cm LST-2 BOTTOM Table C-2: Depth profile of Munsell soil colour assignments from the low sulfur tailings, core #2. C.1.3 MT-1: main tailings (1.0 wt. % S). tailings surface was dry when sampled The MT-1 core, 86 cm in length, is coarse grained except for a 2.5 cm thick bed of fine-grained material at a depth of 57 cm. There is a gradual change in colour with depth: the top of the core is yellower, and grades into browns and further to greys at the bottom of the core. The indexed colours are tabulated below. DEPTH COLOUR MUNSELL (CM) NOTATION 0-11 olive yellow 2.5Y 6/6 11-20 olive grey 5Y 5/2 20-48 olive brown 2.5Y 4/4 48-58 olive 5Y 5/3 58-60 light grey 2.5Y 7/0 60-68 olive 5Y 5/3 68-71 olive yellow 2.5Y 6/6 71-84 dark olive grey 5Y 3/2 TOP 0 cm 94 cm 2.5Y6/6 olive yellow 5Y5/2 olive grey 2.5Y4/4 olive brown 5Y5/3 olive 2.5Y7/0 light grey 5Y5/3 olive 2.5Y6/6 olive yellow 5Y3/2 dark olive grey Table C-3: Depth profile for Munsell soil colour assingments in the main tailings lysimeter, core #1. MT-1 BOTTOM 213 C.l.4 MT-2: main tailings (1.0 wt. % S), tailings surface was wet when sampled The MT-2 core is fine grained throughout the length of the core except for a less well consolidated, coarser grained zone beginning at a depth of 36 cm and extending to 43 cm. The total length of the core is 68 cm, the core is predominantly light grey, with a few sporadic occurrences of yellow coloured tailings (table C-4). TOP 5Y6/1 grey 5Y7/2 + 10YR6/1 mottled grey+ pale yellow 7.5YR5/1 grey 2.5YR5/1 dark greyish brown 7.5YR5/1 grey Table C-4: Depth profile for the Munsell soil colour assignments in MT-2 the main tailings lysimeter, core #2. BOTTOM C.l.5 TT-1: total tailings (2.5 wt. % S), tailings surface was dry when sampled 0 cm D E P T H C O L O U R M U N S E L L (CM) N O T A T I O N 0-14 grey 5Y 6/1 14-34 mottled pale yellow and grey 5Y 7/2 and 10YR6/1 34-68 grey (with a section of 7.5YR5/1 dark greyish brown) (2.5YR 4/2) This core, 105 cm in length, is coarse grained and relatively poorly consolidated. The upper 23 cm of the tailings are yellowish brown and are separated from the bottom of the core by a grey layer that is well consolidated. Below this layer, the tailings are again poorly consolidated and grey, gradually becoming darker grey with depth. 214 TOP D E P T H C O L O U R M U N S E L L (CM) N O T A T I O N 0-23 yellowish brown 10YR5/6 23-25 grey 10YR6/1 25-59 olive grey 5Y 4/2 59-109 very dark grey 5Y 3/1 0 cm Table C-5: Depth profile of the Munsell soil colour assignments in the total tailings lysimeter, core #1. 109 cm 10YR5/6 yellowish brown 10YR6/1 grey 5Y4/2 olive grey 5Y3/1 very dark grey TT-1 BOTTOM C.J.6 TT-2: total tailings (2.5 wt. % S), tailings surface was wet when sampled The TT-2 core is predominantly fine grained and grey. The upper 33 cm of this 76 cm core contains sections of yellow tailings unevenly dispersed throughout. The overall colour of the core gradually darkens with depth. A thin bed of coarse grained tailings, approximately 1 cm in thickness, is present at the 70 cm mark (table C-6). TOP D E P T H C O L O U R M U N S E L L " cm (CM) N O T A T I O N 0-33 grey (with pods of 5Y 5/1 (and 10YR 7/8) yellow) 33-76 | grey | - 7.5YR 5/0 Table C-6: Depth profile of the Munsell soil colour assignments in the total tailings lysimeter, core #2. 76 cm TT-2 BOTTOM 5Y5/1 (spots of 10YR7/8)grey (spots of yellow) 7.5YR5/0 grey 215 C.2 Laboratory Oxidation Column Samples C.2.1 LST-3: low sulfur tailings (0.4 wt. % S) The entire core, 60 cm in length, is coarse grained and medium grey in colour with yellow tones in the upper 8 cm of the core, which gradually darkens with depth. TOP D E P T H (CM) C O L O U R M U N S E L L N O T A T I O N 0-63 olive grey 5Y 4/2 Table C-l: Depth profile of the Munsell soil colour assignments in the low sulfur tailings oxidation column. C.2.2 MT-3: main tailings (J.O wt. % S) 0 cm 5Y4/2 olive grey 63 cm LST-3 BOTTOM This core, 62 cm long, is homogeneously coarse grained, but shows distinct colour changes with depth. The upper 20 cm is light brown, grading into an area of spotted yellowish-brown and grey, becoming a darker grey near the bottom. TOP D E P T H C O L O U R M U N S E L L (CM) N O T A T I O N 0-20 light olive brown 2.5Y 5/6 20-37 mottled yellowish 10YR 5/8 and brown and grey 2.5Y 5/0 37-42 grey 2.5Y 5/0 42-47 olive grey 5Y4/3 47-62 dark grey 2.5Y 4/0 0 cm 62 cm 2.5Y5/6 light olive brown 10YR5/8 + 2.5Y5/0 mottled yellowish brown with grey 2.5Y5/0 grey 5Y4/3 olive grey 2.5Y4/0 dark grey Table C-8: Depth profile of the Munsell soil colour assignments in the main tailings oxidation column. MT-3 BOTTOM 216 C.2.3 TT-3: total tailings (2.5 wt. % S) This core, as seen with MT-3 and LST-3, is coarse grained and well consolidated. The colour variation is more distinct, but similar to that seen in MT-3. The top 6 cm is light brown, becoming spotted yellowish brown and grey to a depth of 28 cm. Following this zone are grey tailings that vary slightly in colour with depth, becoming dark grey at the bottom to a total length of 63 cm. TOP D E P T H C O L O U R M U N S E L L (CM) N O T A T I O N 0-6 light olive brown 2.5Y 5/6 6-28 mottled yellowish 10YR 5/8 and brown and grey 2.5Y 5/0 28-37 dark greyish brown 2.5Y 4/2 37-63 dark grey 2.5Y4/0 Table C-9: Depth profile of the Munsell soil colour assignments in the total tailings oxidation column. 0 cm 63 cm 2.5Y5/6 light olive brown 10YR5/8 + 2.5Y5/0 yellowish brown with brown 2.5Y4/2 dark greyish brown 2.5Y4/0 dark grey TT-3 BOTTOM C.3 Munsell Notation The Munsell color system is based on Hue, Value, and Chroma, which are given separate values and combined in that order to give a designation to a colour. Hue indicates the relation to red, yellow, green, blue, and purple. The hue is represented by the letter abbreviation of the colour of the rainbow, and is preceded by a number from 0 to 10; 0 indicates red, and it becomes more yellow as the number increases to 10. The Value indicates its lightness, and consists of a number from 0, for absolute black, to 10, for absolute white. The notation for Chroma, which indicates the colour's strength, or departure from a neutral colour of the same lightness, is separated from the Value by a virgule and consists of numbers beginning at 0 for neutral greys and increasing at equal intervals to a maximum of 20. For example, 5YR 5/6 is a colour of Hue 5 yellow-red, Value 5, Chroma 6. 217 Appendix D Approximate modal abundance of primary minerals in the Copper Cliff tailings. note: LSTl=low sulfur tailings, dry surface, LST2=low sulfur tailings, wet surface, LST3=low sulfur tailings column; MTl=main tailings, dry surface, MT2=main tailings, wet surface, MT3=main tailings column;TTl=total tailings, dry surface, TT2=total tailings, wet surface, TT3=total tailings colunui; PT3=pyrrhotite-rich tailings column. The numbers following the hyphen in the sample label give the depth of the sample from the surface (in cm). Abbreviations are: quartz (Qz), plagioclase (Plag), potassium feldspar (K-spar), chlorite (CI), hornblende (Hb), actinolite (Act), biotite (Bt), clinopyroxene (Cpx), orthopyroxene (Opx), apatite (Ap), pyrrhotite (Po), magnetite + ilmenite (Mt +IL), chalcopyrite (Cpy), pentlandite (Pent) and pyrite (Py). 218 Q. a. o C N LO C N C N Q. < a. O C N C N C N C N C N C N C N C N C N C N C N C N C N x Q. o CD C N C N C N C N i n oo oo m m m LO LO C D CD oo C N m oo oo C N oo oo oo C N C N C N m C N C N C N C N C N C N CO m C N CO C N C N CN CO C N C N C N C N C N C N C N LO LO m co C N oo OO oo C N 00 m 00 m co co C N C N co i n oo oo C N C N C N C N C N C N LO LO m i n co co i n m C N i n oo LO oo O) CL m CO CO CO CO co co co co 219 T3 0- V tra ce  tra ce  tra ce  tra ce  V V V tr ac e tr ac e V tr ac e Pe nt  tr ac e tr ac e tr ac e tr ac e tr ac e tr ac e tra ce  tra ce  tra ce  tr ac e V V V tr ac e tra ce  tra ce  tr ac e tra ce  Cp y tr ac e tr ac e tr ac e tr ac e tr ac e tr ac e t— V tr ac e tr ac e tr ac e T — V T — LO d T — V LO d V V V V CM d tr ac e V V V V V V V tr ac e tr ac e tr ac e M t +  IL  V V V d V OJ d o Q . 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