Instituto de Metalurgia, Facultad de Ingeniería, Universidad Autónoma de San Luis Potosí, Av. Sierra Leona # 550, Lomas 2a. Sección, 78210, San Luis Potosí, S.L.P., Mexico.
Sci Total Environ. 2011 Sep 1;409(19):3971-9. doi: 10.1016/j.scitotenv.2011.06.055. Epub 2011 Jul 19.
Exploitation of polymetallic deposits from calcareous mining sites exposes galena and others sulfides to weathering factors. Galena weathering leads to the formation of lead phases (e.g., PbSO(4), PbCO(3)) with a higher bioaccessibility than galena, thus increasing the mobility and toxicity of lead. Despite the environmental impacts of these lead phases, the mechanisms of galena oxidation and the transformation of lead secondary phases, under neutral-alkaline carbonated conditions, have rarely been studied. In this work, an experimental approach, combining electrochemical and spectroscopic techniques, was developed to examine the interfacial processes involved in the galena weathering under simulated calcareous conditions. The results showed an initial oxidation stage with the formation of an anglesite-like phase leading to the partial mineral passivation. Under neutral-alkaline carbonated conditions, the stability of this phase was limited as it transformed into a cerussite-like one. Based on the surface characterization and the formation of secondary species, the weathering mechanisms of galena in calcareous soil and its environmental implications were suggested.
从钙质矿山开采多金属矿床会使方铅矿和其他硫化物暴露于风化因素之下。方铅矿风化会导致比方铅矿具有更高生物可利用性的铅相（例如 PbSO4、PbCO3）的形成，从而增加铅的迁移性和毒性。尽管这些铅相具有环境影响，但在中性-碱性碳酸条件下，方铅矿氧化和次生铅相转变的机制很少得到研究。在这项工作中，开发了一种实验方法，结合电化学和光谱技术，来研究在模拟钙质条件下方铅矿风化涉及的界面过程。结果表明存在一个初始氧化阶段，形成类似于硫酸钡的阶段，导致部分矿物钝化。在中性-碱性碳酸条件下，由于其转化为类似于碳酸铅的相，这种相的稳定性受到限制。基于表面特征和次生物质的形成，提出了方铅矿在钙质土壤中的风化机制及其环境意义。
