Planning and implementing solutions for artisanal gold mining sites, preventing environmental impacts and rehabilitating degraded areas : a Brazilian case study

• Main Author: Sousa, Rodolfo Neiva de
• Language: English
• Published: University of British Columbia 2010
• Online Access: http://hdl.handle.net/2429/27950

Artisanal small scale gold mining (ASGM) is a large source of environmental, health and safety problems in more than 70 developing countries, employing more than 15 million people, motivated by the current high price of gold and lack of better economic opportunities. Around 200,000 miners are located in Brazil with 40,000 concentrated in the Tapajos River Basin, in the Amazon. In this region, they extract gold by using rudimentary processes, causing mercury contamination, river siltation and deforestation. This thesis conducted research in the Tapajós region highlighting the strengths of some initiatives introduced by the GEF/UNDP/UNIDO Global Mercury Project from 2002 to 2008. Its training program was delivered to 4,200 artisanal miners in 141 mining sites, and it focused on disseminating 20 good mining practices. Performance indicators have shown that the conformance to standards before and after the program improved from 22 to 51%, with highest success on reduction of mercury (43%) and river siltation (37%), and improvement of sanitation (40%) in the participating sites. This study suggests the use of a heuristic approach to environmental impact assessment and ways to address those variables in intervention programs through training and education. The study also presents a successful rehabilitation initiative using simple local materials. In the participating sites 128 pits were backfilled after training and some of them revegetated. In another case study, a pilot plant to pre-concentrate gold with centrifuge followed by intensive cyanidation of the concentrate in a ball mill has demonstrated to be a fast and advantageous alternative to replace the current 20-day vat leaching or even amalgamation. This pilot study reduced cyanide consumption more than 20 times and may represent an economy of US$150,000/a in NaCN. Finally, this study analyzes 20 Brazilian regulations that affect ASGM, shows that many of them have not been effective, and suggests recommendations that would help to organize the miners and give them proper access to training, technical assistance and technology.