(NH4)2S2O8氧化载金黄铁矿规律及E-pH研究

采用基于硫酸根自由基(SO4-·)的高级氧化技术,将(NH₄)₂S₂O₈作为氧化剂氧化预处理黄铁矿。考察了(NH₄)₂S₂O₈和FeSO₄浓度、浸出温度、浸出时间对氧化浸出黄铁矿效果的影响。结果表明,采用热活化(NH₄)₂S₂O₈产生SO₄-·预处理黄铁矿,在(NH₄)₂S₂O₈浓度0.395 mol/L、浸出温度70 ℃、浸出时间8 h条件下,黄铁矿浸出率可达73.71%。通过动力学方程拟合,确定该体系浸出黄铁矿可采用收缩核动力学模型描述,浸出黄铁矿过程中反应速率的决定步骤为内扩散速率,其表观活化能为50.57 kJ/mol。通过绘制FeS₂-(NH₄)₂S₂O₈-H₂O体系E-pH图分析可知,常温下过硫酸盐溶液具有较高的氧化还原电位,理论上采用过硫酸盐氧化分解产生SO₄-·浸出黄铁矿具有可行性。

Oxidation of Gold Bearing Pyrite by (NH4)2S2O8 and Its E-pH Diagram

By adopting an advanced oxidation process based on sulfate radicals (SO₄-·), pyrite was pretreated with (NH4)2S2O8 as an oxidant. The effects of the concentration of ammonium persulfate and ferrous sulfate, leaching temperature and leaching time on the oxidative leaching of pyrite were investigated. It is found that thermal activation of (NH₄)₂S₂O₈ can generate SO₄-·, which is then used to pretreat pyrite. With the concentration of (NH₄)₂S₂O₈ at 0.395 mol/L, the leaching process at 70 ℃ for 8 h can result in the leaching rate of pyrite up to73.71%. Based on the kinetic equation fitting, it is determined that the pyrite leaching process can be described as the shrinking core model, and the internal diffusion rate is the determining factor of the reaction rate during the pyrite leaching process, and its apparent activation energy is calculated to be 50.57 kJ/mol. Based on the analysis of the drawn E-pH diagram of the FeS₂-(NH₄)₂S₂O₈-H₂O system, it can be known that the persulfate solution has a very high redox potential at room temperature. Theoretically, it is feasible to leach pyrite with SO4-· that is generated after the oxidative decomposition of persulfate.