基于同时平衡原理的Au-I--H 2 O系热力学分析

摘要

采用同时平衡原理对Au-I−-H 2 O系的浸金热力学进行分析，分别研究溶液与固体Au以及AuI沉淀与固体Au平衡时的φ−pH关系、AuI存在条件和溶液中含金组分的变化规律。结果表明：随着溶液中含金组分的总浓度c T (Au)的降低或含碘组分的总浓度c T (I−)的增加，还原电位φsol/Au迅速降低，Au3+/Au 2 O 3的平衡pH值增大，非常有利于金的碘化浸出；随着溶液中c T (I−)逐渐增加，出现AuI沉淀且其沉淀量呈先增大后减小的趋势；在c T (Au)为1×10−4 mol/L的条件下，当溶液中cT(I−)浓度大于0.0021 mol/L时，可避免AuI沉淀的生成，金主要以AuI2−络合离子形式存在。Au-I−-H 2 O系的浸金热力学分析为金的高效碘化浸出提供了理论依据。%Thermodynamic analysis of Au-I−-H2O system was carried out based on the principle of simultaneous equilibrium. Theφ−pH programs of balance with solution and Au, solid AuI and Au were investigated. Also, the existence condition of AuI precipitation and change-rule of gold-bearing components were studied. The results show that with decreasingcT(Au) or increasingcT(I−) in the solution,φsol/Au reduces rapidly compared to the standard potential of Au, and the balance pH value of Au3+/Au2O3 increases. This is beneficial to gold leaching with iodine-iodide. As the cT(I−) increases gradually in the solution, AuI precipitation appears and the trend of AuI precipitation amount increases firstly and then reduces. When thecT(Au) is 1×10−4mol/L, if thecT(I−) is more than 0.0021 mol/L, AuI precipitation will not occur, meanwhile, the main complex ion is AuI2−. The thermodynamic analysis of Au-I−-H2O system provides theoretical basis for the efficient gold leaching with iodine-iodide.