Mill leaching: a viable substitute for mercury amalgamation in the artisanal gold mining sector?

Human mercury exposure associated with small-scale gold mining in Burkina Faso

“…Several recent publications Veiga et al 2009;Jønsson et al 2009) showed that it is possible to reduce mercury exposure on small-scale gold mine sites, by using retorts, tools for recycling mercury during amalgamation. Newly, a publication dealt with a proposal of international guidelines on mercury management in small-scale gold mining (Spiegel and Veiga 2010).…”

Mercury balance in amalgamation in artisanal and small-scale gold mining: identifying strategies for reducing environmental pollution in Portovelo-Zaruma, Ecuador

“…The following steps are suggested to reduce/eliminate mercury pollution in the Portovelo-Zaruma region: a) elimination of whole ore and leftover amalgamation using ''chanchas''; b) allow miners to amalgamate only gravity concentrates; c) promotion of cyanidation of concentrates either in agitated tanks or using the ''chanchas'' for mill-leaching [32], and d) promotion of the use of individual retorts when amalgam is burned and filters when the doré is melted. Using retorts, it is estimated that nearly 97% of the total mercury introduced in the process can be recovered when only gravity concentrates are amalgamated.…”

“…The eradication of mercury in Portovelo-Zaruma can become a reality if miners recognize how efficient cyanide can be: the authors demonstrated the possibility of using cyanide in the ''chanchas'' to leach concentrates from the sluice boxes. This yielded 95% gold extraction from the gravity concentrates against 26% when miners amalgamate the same concentrate in ''chancha'' [32]. Some miners are now aware about the possibility of adopting the Table 2 Average mercury distribution in processing centers (g Hg/tonne of material processed).…”

“…A campaign to use small concentration procedures for small amounts of ore could add another dimension to the ''Chancha'' processing centers. Local and federal governments should provide training for the Chancha centers to avoid the amalgamation of the whole ore, replacing this with cyanidation in small scale [32].…”

International guidelines on mercury management in small-scale gold mining

“…This paper discusses the challenge of minimizing mercury use as well as key measures for incorporation in the Guidelines, building upon several previous studies on mercury issues in gold extraction [15][16][17][18][19][20][21][22][23][24] that have been published in the Journal of Cleaner Production. The paper also highlights the need for participatory planning in communities to discuss and adapt guidelines appropriately, in order to develop technology transfer strategies, regulatory guidelines and strategic priorities that are suitable to the local context.…”