Separation of Co(II) and Ni(II) from Hydrochloric Acid Leach Liquor by Solvent Extraction and Crystallization

A novel hydrometallurgical process was developed to separate cobalt and nickel from hydrochloric acid leach liquor of mixed nickel-cobalt hydroxide precipitate. After the removal of Al(III), Ca(II), Cu(II), and Fe(III) by extraction with P204, Co(II) was selectively extracted over Ni(II) and Mg(II) using N235. The extraction of cobalt can reach 99.99%, while the extraction of nickel and magnesium is both less than 1% after four-stage countercurrent extraction with an organic solution consisting of 30 vol% N235 and 15 vol% TBP in sulfonated kerosene while keeping the contact time 5 min, O/A ratio 2:1. The stripping of cobalt can reach higher than 99.99% by pure water after three-stage countercurrent stripping. The nickel chloride can be selectively precipitated by passing into HCl gas, and the purity of that meets the standard specification if the magnesium concentration was less than 24 g/L.

Automated summary

A novel hydrometallurgical process has been developed to separate cobalt and nickel from hydrochloric acid leach liquor. The process utilizes selective extraction and stripping methods, achieving high separation efficiency.