Applied Geochemistry, Luleå University of Technology, Luleå, Sweden.
Ore Geology, Luleå University of Technology, Luleå, Sweden.
Environ Sci Pollut Res Int. 2020 Feb;27(6):6180-6192. doi: 10.1007/s11356-019-07305-1. Epub 2019 Dec 21.
More knowledge of the geochemical behavior of tungsten (W) and associated contamination risks is needed. Therefore, weathering of scheelite (CaWO) and secondary sequestration and transport of W to groundwater in historical skarn tailings and surface water downstream of the tailings were studied. The tailings contained 920 mg/kg W, primarily in scheelite. Mineralogical and geochemical analyses were combined to elucidate the geochemical behavior of W in the tailings, and water samples were taken monthly during 2018 to monitor its mobility. In the tailings, a large peak of W was found at 1.5 m depth. There, 30 wt%. of W was present in easily reducible phases, indicating former scheelite weathering. Currently, W is being released from scheelite to water-soluble phases at 2.5 m depth. The release of WO is hypothetically attributed to anion exchange with CO released from calcite neutralizing acid produced from pyrrhotite oxidation in the upper tailings and transported downwards to pH conditions > 7. Higher concentrations of dissolved W were found in the groundwater and particulate W in downstream surface water than in reference water, but they were lower than current contamination thresholds. Tungsten showed correlations with hydrous ferric oxides (HFO) in both the tailings and surface water.
需要更多关于钨（W）的地球化学行为及其相关污染风险的知识。因此，研究了白钨矿（CaWO）的风化以及 W 从历史斑岩尾矿向地下水和尾矿下游地表水的二次固定和迁移。尾矿中含有 920mg/kg 的 W，主要以白钨矿的形式存在。矿物学和地球化学分析相结合，以阐明 W 在尾矿中的地球化学行为，并在 2018 年每月采集水样以监测其迁移性。在尾矿中，在 1.5 米深处发现了一个很大的 W 峰值。在那里，30wt%的 W 存在于易还原相中，表明曾经有白钨矿风化。目前，W 正在从白钨矿向 2.5 米深处的水溶性相中释放。WO 的释放假设是与从黄铁矿氧化产生的酸中释放的 CO 进行阴离子交换，这种酸向上运输到 pH 值大于 7 的条件下。在地下水和下游地表水的颗粒状 W 中的溶解 W 浓度高于参考水，但低于当前的污染阈值。钨在尾矿和地表水的水合氧化铁（HFO）中都显示出相关性。
