Centre for Mineral Technology (CETEM/MCTI), Av. Pedro Calmon, 900, Cidade Universitária, Rio de Janeiro, RJ, 21941-908, Brazil.
EcoHealth Approach at Mining Sites - EHM/CNPq, Research Member, Rio de Janeiro, Brazil.
Environ Geochem Health. 2024 Mar 2;46(3):101. doi: 10.1007/s10653-024-01881-z.
This study presents a picture of ASGM in Brazil and prospective numbers on mercury emissions and releases in 2016, when the country declared production of about 90 tonnes of gold, of which circa 25 tonnes came from ASGM. However, it is also necessary to consider the illegal production of ASGM which is estimated to vary between 10% and eight times more than the legal production. The proposed method included: organization of spatial data on legal ASGM output, stakeholder identification and meetings, mercury metallurgical balance, quantitative measurement of mercury in the atmosphere and qualitative social aspects such as the miners' economic dependence on the managers and scenarios of illegal ASGM annual production. The main results revealed that the initial mercury (Hg)-gold (Au) production ratio was higher for the primary whole ore than for the concentrate secondary ore, which is the most frequent type of Brazilian ASGM. The amalgam filtering technique followed by mercury recovery is routine, decreasing the Hg releases to tailings ponds or to soil and water bodies. The mercury emissions by thermal decomposition of amalgam are independent of the initial mercury mass, depending only on the mercury in the amalgam and the (adequate) use or not of emission control systems. Illegal activities reduce the availability and proper use of these systems, resulting in higher emissions. Mercury emissions from ASGM in Brazil may increase the global mercury emissions estimates, while their mercury releases may represent a marginal increase. As the mercury emitted may be trapped by the rainforests added to the mercury released, the environmental contamination may pose health risks to Amazonian population, which requires immediate action.
本研究呈现了巴西手工和小规模采金业的概况，并预测了 2016 年的汞排放量和释放量，当时该国宣布生产了约 90 吨黄金，其中约 25 吨来自手工和小规模采金业。然而，还需要考虑到非法手工和小规模采金业的生产，据估计，其产量是合法生产的 10%到 8 倍不等。所提出的方法包括：组织关于合法手工和小规模采金业产量的空间数据、确定利益相关者并召开会议、汞冶金平衡、大气中汞的定量测量以及定性的社会方面，如矿工对管理者的经济依赖和非法手工和小规模采金业的年度生产情景。主要结果表明，原矿的初始汞（Hg）-金（Au）生产比高于精选后的二次矿，这是巴西手工和小规模采金业最常见的类型。汞齐过滤技术随后进行汞回收，减少了汞向尾矿池或土壤和水体的释放。汞齐热分解产生的汞排放与初始汞质量无关，仅取决于汞齐中的汞以及排放控制系统的使用（或不使用）。非法活动减少了这些系统的可用性和适当使用，导致排放增加。巴西手工和小规模采金业的汞排放可能会增加全球汞排放的估计值，而其汞释放量可能只会略有增加。由于排放的汞可能被热带雨林吸收，释放的汞也可能被热带雨林吸收，因此环境污染物可能对亚马逊地区的人口构成健康风险，这需要立即采取行动。
