Socio-technical assessment of mercury and gold losses in artisanal and small-scale mining (ASM) operations in Colombia, A

Abstract

In Colombia, the artisanal and small-scale gold mining (ASGM) sector represents about 70% of the mining activities, and approximately 80% of Colombia’s gold comes from this sector. In addition, the ASGM sector in Colombia releases about 90 tons of mercury per year. Although the Colombian government banned mercury in 2018 and has implemented a number of programs aimed at eliminating mercury from ASGM mineral processing systems, mercury use continues to be widespread. A number of scholars have emphasized that in order for miners to stop using mercury, any new technology must be at least or more efficient than mercury at recovering gold. However, there has been a lack of quantification of the efficiency, or gold recovery rate, of ASGM mineral processing to provide a baseline for introducing new technologies. Furthermore, miners’ perceptions on mineral processing and the risks of mercury have been relatively neglected, even though these beliefs can have significant impacts on their decision-making. Therefore, this thesis provides a socio-technical analysis of mercury use in ASGM mineral processing systems in the department of Antioquia in Colombia. Through gold and mercury mass balances and an ethnographic study of ASGM operators, we found that miners maintained relatively accurate knowledge about their mineral processing systems, especially in terms of the amount of gold and mercury they lost during mineral processing. Even so, miners felt that they were recovering as much gold as they could given their current technologies, and they were not interested in recovering the mercury that was lost in the tailings. Furthermore, miners’ awareness of the human health and environmental hazards associated with mercury did not motivate them to change their practices. Instead, they viewed the government’s discourse about the risks of mercury with skepticism, and despite some of their concerns about mercury, they were either hesitant to use or did not have access to mercury alternatives for mineral processing. This thesis demonstrates that socio-technical understandings of mercury use can better inform policy makers and development initiatives aimed at eliminating mercury from ASGM mineral processing systems.