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UBC Theses and Dissertations

Analysis of gold extraction processes of artisanal and small-scale gold minining In Portovelo-Zaruma, Ecuador de Oliveira Gonçalves, Adriana


Artisanal and small-scale gold mining (ASGM) play a significant role in local economies and communities of several developing countries. Worldwide, ASGM is one of the biggest sources of mercury pollution. Every year, artisanal miners release approximately 727 tonnes per year of mercury to the environment. Globally, nearly 16 million people are directly or indirectly involved in ASGM activities using rudimentary techniques. Even though there are substantial potential socio-economic benefits of ASGM, it can be extremely damaging environmentally and often has serious health and safety consequences for workers and surrounding communities. This study focuses mainly on the operations of gold processing centers in Portovelo-Zaruma in southern Ecuador, which represent the largest source of environmental contamination in the Puyango-Tumbes River Basin. Furthermore, this study aimed to characterize the types of processing centers currently operating in Portovelo-Zaruma to determine the amount of gold produced, the amount of mercury and cyanide used and lost by these processing centers, and the amount of tailings produced in the region. This study explains how contamination is generated by artisanal and small-scale miners through a comprehensive analysis of the processing centers and also analyzes aspects of different intervention approaches. Approximately 1.6 million tonnes/annum of tailings with cyanide and heavy metals have been produced by the 87 processing centers in the studied region. In 2015, approximately 6.0 tonnes of gold/annum were produced by all processing centers. In 2015, there was an increase of NaCN use of approximately 31% in comparison to 2013. Each plant uses on average 2.05 tonnes/month of NaCN, totalling 24.6 tonnes/a/plant. Considering that 95% of the plants are using cyanidation to process ore or gravity separation tailings, this would amount to an estimated yearly consumption of NaCN of approximately 1550 and 2040 tonnes for 2013 and 2015, respectively. In 2013, 78% of the processing centers were using amalgamation with 1.5 tonnes/a of mercury lost to the environment. In 2015, 65% of the plants were still using amalgamation, mainly chanchas, and the total mercury lost decreased to 576 kg/a in which 243 kg/a was lost with tailings and 333 kg/a lost to the atmosphere.

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