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本文以广西大厂锡石-硫化物矿区巴里尾矿库的富碳酸盐尾矿(堆放了20余年)作为研究对象,采用BCR三步提取法研究Zn、Cd、Pb和As的化学形态分量以及其总含量在该尾矿铅垂剖面中的分布,并结合尾矿的结构构造、次生和原生矿物成分及其变化等分析,探讨在氧化/酸化条件下富碳酸盐尾矿中重金属的释放机制。研究结果表明:(1)尾矿下层原尾矿中重金属主要以稳定或较稳定的残渣态(As、Pb、Zn、Cd)、氧化物结合态(Pb)及硫化物结合态(Zn、Cd)形式赋存。在酸水淋滤作用下,原尾矿中重金属的释放顺序为Cd≈Zn>Pb>As;(2)尾矿上部厚层状氧化硬层(厚度1~1.5m)中,Zn、Cd以酸可溶态大量富集,具有较强的迁移性;As、Pb主要以残渣态以及氧化物结合态赋存,其迁移性较差。因此,富含碳酸盐的硫化物尾矿经过氧化作用具有释放多种重金属的潜能。由于这类尾矿中各重金属的赋存状态存在差异性,因此对其迁移性及环境效应须具体分析。
In this paper, carbonate-rich tailings (deposited more than 20 years) in the Bari tailing pond of Guangxi Caidui cassiterite-sulfide mining area were selected as research objects. The chemical composition of Zn, Cd, Pb and As was studied by BCR three-step extraction And its total content in the tailings vertical profile of the distribution, combined with the structure of tailings, secondary and primary mineral composition and its changes in analysis of oxidation / acidification conditions in carbonate-rich tailings of heavy metals Release mechanism. The results show that: (1) The heavy metals in the tailings of the tailings mainly consist of stable or stable residuals (As, Pb, Zn, Cd), oxide bound (Pb) and sulfide bound (Zn, Cd) Form of memory. In acid leaching, the order of release of heavy metals in the original tailings was Cd ≈ Zn> Pb> As. (2) In the thick tailings upper hard oxide layer (1 ~ 1.5 m in thickness) Soluble in a large amount of enrichment, with a strong mobility; As, Pb mainly in the residual state and oxide-bound state of the occurrence of its mobility is poor. Therefore, carbonate-rich sulfide tailings have the potential to release many heavy metals through oxidation. Due to the differences in the occurrence of heavy metals in such tailings, their migration and environmental effects must be analyzed in detail.