Estimation of Mercury Losses and Gold Production by Artisanal and Small-Scale Gold Mining (ASGM)

Akihiro Yoshimura,Marcello M Veiga,Koyo Suemasu

doi:10.1007/s40831-021-00394-8

Akihiro Yoshimura, Marcello M Veiga + Show 1 more

Open Access

https://doi.org/10.1007/s40831-021-00394-8

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Abstract

Artisanal and small-scale gold mining (ASGM) utilizes mercury (Hg) for the extraction of gold (Au) and is responsible for the largest anthropogenic source of emissions and releases of Hg to the environment. Previous estimates of Hg use in ASGM have varied widely. In this effort, Hg losses in ASGM were derived from the difference between estimates of total Au production and the production reported by conventional gold mining. On the basis of this result, the average ratio of Hg lost to Au produced in ASGM was estimated to be 1.96 in Africa, 4.63 in Latin America, and 1.23 in Asia. The difference among regions can be attributed to the amalgamation procedure used by the miners, in which whole-ore amalgamation is predominant in Latin America and Asia. The obtained estimated ratio of Hglost:Auproduced suggested the possibility to detect either Au or Hg smuggling from one country to another. On the other hand, the importance of considering cyanidation in ASGM was also suggested.Graphical

Highlights

Mercury (Hg) released [1] to the environment, including air, water, and land, causes severe environmental and health impacts
When miners amalgamate the whole ore in small ball mills, the mercury loss can be as high as 15 parts of mercury per part of gold produced [5]
Nigeria, Sierra Leone, and Mozambique, where the only statistical data available for total gold production are from United States Geological Survey (USGS) [28], the gold production was estimated by the apportionment of “others” in the Gold Fields Mineral Services (GFMS) data, and applying the USGS data

Summary

Introduction

Mercury (Hg) released [1] to the environment, including air, water, and land, causes severe environmental and health impacts. Releases from artisanal small-scale gold mining (ASGM) operations are gaining global attention due to its high contribution to the overall pollution levels. Gold is extracted by amalgamation of concentrates or the whole ore, and the amalgam, usually with 40–50% mercury, is heated. When miners amalgamate the whole ore in small ball mills, the mercury loss can be as high as 15 parts of mercury per part of gold produced [5]. It has been reported that the wholeore amalgamation process requires 10–25 g of mercury for the production of 1 g of gold while the concentrate amalgamation process requires only 1–3 g of mercury [6]

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