Department of Earth Sciences. Faculty of Experimental Sciences, University of Huelva, Campus El Carmen, Avenida 3 de marzo s/n, Huelva 21007, Spain; Research Center on Natural Resources, Health and the Environment. University of Huelva, Campus "El Carmen", Huelva 21007, Spain.
Department of Earth Sciences. Faculty of Experimental Sciences, University of Huelva, Campus El Carmen, Avenida 3 de marzo s/n, Huelva 21007, Spain; Research Center on Natural Resources, Health and the Environment. University of Huelva, Campus "El Carmen", Huelva 21007, Spain.
J Hazard Mater. 2023 Apr 15;448:130948. doi: 10.1016/j.jhazmat.2023.130948. Epub 2023 Feb 8.
Unlike acidic sulfide mine wastes, where metal/loid mobility and bioaccessibility has been widely studied, less attention has been paid to alkaline cyanide heap leaching wastes. Thus, the main goal of this study is to evaluate the mobility and bioaccessibility of metal/loids in Fe-rich (up to 55%) mine wastes resulting from historical cyanide leaching activities. Wastes are mainly composed of oxides/oxyhydroxides (i.e. goethite and hematite), oxyhydroxisulfates (i.e. jarosite), sulfates (i.e., gypsum, evaporitic sulfate salts), carbonates (i.e., calcite, siderite) and quartz, with noticeable concentrations of metal/loids (e.g., 1453-6943 mg/kg of As, 5216-15,672 mg/kg; of Pb, 308-1094 mg/kg of Sb, 181-1174 mg/kg of Cu, or 97-1517 mg/kg of Zn). The wastes displayed a high reactivity upon rainfall contact associated to the dissolution of secondary minerals such as carbonates, gypsum, and other sulfates, exceeding the threshold values for hazardous wastes in some heap levels for Se, Cu, Zn, As, and sulfate leading to potential significant risks for aquatic life. High concentrations of Fe, Pb, and Al were released during the simulation of digestive ingestion of waste particles, with average values of 4825 mg/kg of Fe, 1672 mg/kg of Pb, and 807 mg/kg of Al. Mineralogy may control the mobility and bioaccessibility of metal/loids under rainfall events. However, in the case of the bioaccessible fractions different associations may be observed: i) the dissolution of gypsum, jarosite and hematite would mainly release Fe, As, Pb, Cu, Se, Sb and Tl; ii) the dissolution of an un-identified mineral (e.g., aluminosilicate or Mn oxide) would lead to the release of Ni, Co, Al and Mn and iii) the acid attack of silicate materials and goethite would enhance the bioaccessibility of V and Cr. This study highlights the hazardousness of wastes from cyanide heap leaching, and the need to adopt restoration measures in historical mine sites.
与金属/类金属的迁移性和生物可利用性已得到广泛研究的酸性硫化物矿山废物不同，碱性氰化物堆浸废物受到的关注较少。因此，本研究的主要目的是评估历史氰化物浸出活动产生的富含铁（高达 55%）矿山废物中金属/类金属的迁移性和生物可利用性。废物主要由氧化物/氢氧化物（如针铁矿和赤铁矿）、氧氢氧硫酸盐（如铁矾）、硫酸盐（如石膏、蒸发硫酸盐盐）、碳酸盐（如方解石、菱铁矿）和石英组成，具有显著浓度的金属/类金属（例如，1453-6943mg/kg 的 As、5216-15672mg/kg 的 Pb、308-1094mg/kg 的 Sb、181-1174mg/kg 的 Cu 或 97-1517mg/kg 的 Zn）。废物与降雨接触后表现出很高的反应性，与碳酸盐、石膏和其他硫酸盐等次生矿物的溶解有关，在某些堆层中，硒、铜、锌、砷和硫酸盐的含量超过了危险废物的阈值，这对水生生物可能构成重大风险。在模拟废物颗粒消化摄入过程中，释放出大量的 Fe、Pb 和 Al，平均值分别为 4825mg/kg 的 Fe、1672mg/kg 的 Pb 和 807mg/kg 的 Al。矿物学可能控制着降雨事件中金属/类金属的迁移性和生物可利用性。然而，在生物可利用的金属/类金属中，可能会观察到不同的结合：i）石膏、铁矾和赤铁矿的溶解主要会释放 Fe、As、Pb、Cu、Se、Sb 和 Tl；ii）未识别矿物（如铝硅酸盐或 Mn 氧化物）的溶解会导致 Ni、Co、Al 和 Mn 的释放；iii）硅酸盐材料和针铁矿的酸侵蚀会增强 V 和 Cr 的生物可利用性。本研究强调了氰化物堆浸废物的危害性，以及在历史矿山场地采取恢复措施的必要性。
