Process research on the preparation of high-purity cobalt chloride by chemical precipitation

As the precursor of high-purity cobalt, the purity of cobalt chloride has an important influence on the properties of the cobalt target prepared subsequently. In recent years, in addition to ion exchange and extraction, chemical precipitation is a promising method for the purification of cobalt chloride. High-purity cobalt chloride was prepared by chemical precipitation with ammonium hydroxide and dimethylglyoxime as precipitants. The purification mechanism of high-purity cobalt chloride and the depletion mechanism of the main element Co were studied. Inductively coupled plasma-mass spectrometry (ICP-MS) and X-ray diffraction (XRD) were used to characterize the ion concentration, precipitate phase, and depletion products of the main element Co in the solution. The results show that the concentration of impurity elements Al, Cu, and Cr in cobalt chloride solution can be reduced to less than 0.5 mg/L and the concentration of Fe can be reduced to less than 2 mg/L after removing impurities with ammonia. When a small amount of hydrogen peroxide is added to the solution, the concentration of impurity Fe can be reduced to less than 0.82ug/L. In an alkaline environment where nickel dimethylglyoxime is generated, the main element Co is mainly depleted in the form of [Co(NH₃)₅Cl]Cl₂.