摘要
The effect of calcite and dolomite on the oxidation of pyrite was studied using batch-leaching experiments complemented with chemical modeling, solution analysis and solid characterization techniques. Leaching tests conducted at 80℃ and p(O2)=1.013×105 Pa and pH〉13 showed that pyrite alkaline oxidation rate decreased in the presence of both calcite and dolomite, while more detrimental effect was observed in the case of calcite. FE-SEM/EDS analysis exhibited a surface layer containing Ca(in the case of calcite) and Mg(in the case of dolomite) on the pyrite surface, which justified the slowdown in pyrite leaching rate. This surface layer was formed due to partial dissolution of carbonate minerals, which was affected dominantly by the p H and temperature of the leaching solution based on the chemical modeling data. The surface layer was characterized as Ca or Mg hydroxide using XRD and FTIR analysis. It was also found that this layer was thin and continuous in the case of calcite while it was thick and discontinuous in the presence of dolomite.
通过间歇浸出试验,结合化学模拟、溶液分析和固体表征技术,研究方解石和白云石对黄铁矿氧化的影响。在80℃、p(O_2)=1.013×10~5 Pa和pH>13的条件下进行浸出试验。结果表明:在方解石和白云石存在条件下,黄铁矿在碱中的氧化率下降,其中方解石的影响更大。FE-SEM/EDS分析表明,黄铁矿表面含有钙(方解石存在时)和镁(白云石存在时),这是黄铁矿浸出率下降的原因。根据化学模拟结果,这一表面层的形成是由于碳酸盐矿物的部分溶解,主要受浸出液pH值和温度的影响。XRD和FTIR分析表明,表面层为钙或镁的氢氧化物。研究还发现,在方解石存在的情况下,表面层薄,而且是连续的;但在白云石存在条件下,表面层既厚又不连续。
基金
the support of IMIDRO,Iranian Mines & Mining Industries Development & Renovation,for providing the financial support to carry out this research