基于Cu-Mo-NH3-H2O系钼铜分离研究

Separation of Molybdenum and Copper Based on Cu-Mo-NH3-H2O System

铜是钼酸铵产品中需要严格限制的杂质元素。钼焙砂中常含铜,氨浸过程铜钼同时进入浸出液中,从浸出液中除铜常常采用硫化物沉淀法,造成生产成本增加和环境污染,因此铜钼分离是钼酸铵制备的关键问题。绘制了25℃时Cu-Mo-NH3-H2O系组分的浓度对数-pH图,利用热力学平衡图对CuMoO4在氨性和碱性溶液中的溶解行为进行热力学分析,并推断出新型铜钼分离方法。结果表明:氢氧化钠分解钼酸铜,钼进入溶液而铜几乎完全留在渣中,实现铜钼分离;pH 5.5~7.0条件下,氨与铜络合形成铜氨络合物促进钼酸铜分解;降低[N]T, pH值和提高[Mo]T扩大CuMoO4稳定区,不利于Cu(NH3)2+m形成,能从钼酸铵溶液中分离铜。验证试验表明:焙砂中钼优先于铜被氨浸出;提高氨用量有利于铜、钼浸出;降低含铜钼酸铵溶液pH值至5.8,对应溶液铜浓度降至0.098 g·L-1,铜沉淀率达到98.8%,达到了从钼酸铵溶液中除铜的效果。验证实验与理论研究结论相符。

Copper was an impurity element which was strictly restricted in ammonium molybdate products. Copper was often contained in molybdenum calcine. Copper and molybdenum were leached simultaneously in ammonia leaching process. Sulfide precipitation was often used to remove copper from leaching solution, resulting in increased production costs and environmental pollution. Therefore, the separation of copper and molybdenum was a key problem in the preparation of ammonium molybdate. According to the thermodynamic analysis of the alkaline leaching process containing copper and molybdenum roasting, the lgc-pH diagram of Cu-Mo-NH3-H2O system at 25 ℃ was drawn. The thermodynamic equilibrium diagram was used to analyze the thermodynamic analysis of the alkali decomposition of copper containing molybdenum calcic sand, and the new separation method of copper and molybdenum was deduced. The results showed that: sodium hydroxide decomposed copper molybdate, molybdenum dissolved and the copper was almost completely left in the slag to separate copper and molybdenum. At condition of pH 5.5~7.0, the complexing of ammonia and copper to form copper ammonia complex to decompose copper molybdate. Reducing [N]T, pH value and increasing [Mo]T to expand CuMoO4 stable region, but not conducive to the formation of Cu(NH3)2+m, which was beneficial to the separation of copper from ammonium molybdate solution. The test showed that the molybdenum was preferable to the leaching of ammonia compared to copper, and the increase of ammonia was beneficial to the leaching of copper and molybdenum;the pH value of ammonium molybdate solution was 5.8, and the concentration of copper in solution was reduced to 0.098 g·L-1, the precipitation rate of copper reached 98.8%, and the effect of removing copper from ammonium molybdate solution was achieved. The experimental results agreed with the theoretical conclusions.