液氯化法浸出硫化金精矿压热氧化渣的电位变化研究

根据氯化物体系中金的浸出热力学,预测合理的电位和pH值范围。通过对硫化金精矿压热预处理后的氧化渣进行液氯化浸出试验,考察了浸出过程中电位变化与浸金率之间的关系。氯化浸出金适宜的热力学条件为pH值8以下、电位0.9 V以上。从次氯酸钠溶液的氧化能力角度考虑,pH值在4～5.5时其氧化能力较强,此时溶液中氧化剂以HClO为主。对金精矿压热氧化渣的次氯酸钠浸出,为得到较高的浸金率,必须控制至少2 h电位在1.0 V以上。若在浸出过程中电位低于1.0 V,已溶解生成的金氯络合物会再沉淀,使浸金率下降。在初始有效氯质量分数为0.5%、初始pH值为4.0时,可保证2 h内电位在1.0 V以上,此时浸金率可达到96%以上。

Study on potential change of chlorination gold lea oxidation residue of gold sulfide concentrate

According to the thermodynamics of gold leaching in chloride system, the oxidation -reduction potential and pH range was predicted. The relationship between the changing of potential and the gold leaching rate was also investigated in chlorination leaching process of pressure oxidation residue of gold sulfide concentrate. The reasonable thermodynamic conditions of chlorination leaching of gold were that the value of pH should be below 8 and the potential should be more than 0.9 V. For the consideration of oxidizability of sodium hypochlorite solution, the oxidizability was strong between the pH of 4 and 4.5, and then the oxidant in solution was main HC10. In the experiment of chlorination leaching, in order to obtain a higher leaching rate of gold, the conditions must be ensured that the leaching time should be more than two hours and the potential should be controlled at 1. 0V or more. If the potential was lower than 1.0 V in leaching process, dissolved gold chloride complexes would precipitate and the leaching rate of gold would decrease. In this work, the initial concentration of active chlorine was 0.5 %, and the value of pH was 4. 0, the leaching time and the potential could be guaranteed at least two hours and more than 1.0 V respectively, the leaching rate of gold could get more than 96 %.