湿法分解钨酸钴的热力学分析

Thermodynamic analysis of cobalt tungstate's hydrometallurgical decomposition

采用空气(或氧气)氧化法处理WC-Co硬质合金废料时,钴和钨将形成难溶于水的化合物钨酸钴.针对湿法分解钨酸钴的问题,分别对Co-W-H2O体系和Co-W-C-H2O体系进行了热力学分析,获得了一系列平衡关系图.结果表明,钨酸钴在中性溶液中可稳定存在,采用酸分解或碱分解的方式,均可使钨酸钴分解,并实现钨和钴的分离.碳酸盐分解钨酸钴的热力学趋势较大,分解反应可在较低的碳酸盐过量系数下完成.此外,溶液pH值对碳酸盐分解钨酸钴具有较大的影响.

When treating scraps WC-Co hard metal with oxygen or air, cobalt tungstate insoluble in water forms in the oxidation products. Thermodynamic equilibriums of Co-W-H 2O system and Co-W-C-H2O system were studied respectively obtaining a series of equilibrium diagrams to investigate issues related to hydrometallurgical decomposition of cobalt tungstate. The results show that cobalt tungstate is relatively stable in neutral solution. Cobalt tungstate can be decomposed by acid or alkali under certain conditions. Tungsten and cobalt can be separated at the same time. In addition, the decomposition reaction of cobalt tungstate with carbonate can be accomplished at lower excess coefficient of carbonate due to its strong thermodynamic tendency. Solution PH value has a remarkable effect on the reaction.