氨法加压浸出钴铜氧化矿工艺

氨法浸出是基于目标金属与氨形成配合离子进入溶液,实现目标金属与部分杂质的分离,因此浸出过程具有选择性。对钴、铜与氨的配合机制及亚硫酸钠还原性能的影响因素进行了分析。结果表明:提高cNH3/cMe有利于形成稳定性高的钴、铜氨配合离子;降低cSO42-/cSO32-,提高体系pH可降低还原剂还原电位。实验过程采用加压氨浸工艺,在NH3-NH4+-H2O体系中浸出钴铜氧化矿中的钴和铜,研究了总氨浓度、氨铵比、液固比、浸出温度、还原剂用量对氧化矿中钴和铜浸出率的影响。结果表明,在总氨浓度7 mol.L-1、氨铵比2∶1、液固比6∶1、浸出温度100℃、还原剂亚硫酸钠用量为三价钴含量(摩尔比)4倍的最优条件下,钴浸出率可达到95.2%,铜浸出率可达到95.8%。浸出液后续处理工艺简单,氨及铵盐可实现闭路循环,对环境友好。

Process of Ammonium Leaching Oxidation Ore of Cobalt and Copper at High Pressure

Ammonium leaching was a selective process,the principle was that goal metal formed complex ions with ammonia so as to be separated from impurities.The coordination reaction mechanism of ammonia with cobalt and copper and the affective factors of sodium sulfite reduction were analyzed.It showed that increasing the ratio of ammonia was in favor of the stability of complexes,and low reduction potential was available while decreasing the cSO2-4/cSO2-3 and improving the pH value.Cobalt and copper were leached with NH3-NH4+-H2O system at high pressure from cobalt and copper oxide ore.The influence of total concentration,ratio of ammonia to ammonium,ratio of liquid to solid,temperature and amount of reductant on leach rate were studied.The results showed that the leach rate of cobalt and copper was 95.2% and 95.8% respectively under the optimal conditions that total ammonia concentration was 7 mol · L-1,NH3/NH4+ was 2∶ 1,the ratio of liquid to solid was 6∶ 1,leaching temperature was 100 ℃,the amount of the reductant sodium sulfite was 4 times to the amount of trivalent cobalt(mol ratio).Processes after leaching was simple,ammonia and ammonium was recycled and this process benefited environment protection.