METHOD OF CLEANING OFF IRON FROM NICKEL SULPHATE SOLUTION Russian patent published in 2008 - IPC H01M10/54 

FIELD: chemistry.

SUBSTANCE: invention can be used for cleaning off iron impurities from a solution of nickel sulphate NiSO₄ during recycled production of nickelous hydroxide Ni(OH)₂ from used alkaline accumulators. During precipitation of iron from the nickel sulphate solution with calcined soda at pH=3.0-3.3, the ratio of the quantity of iron to the insoluble nickel in the precipitate from the process is about 8-10 g of iron to 1g nickel. After the first iron precipitation stage, the second precipitation stage is carried out at pH of 6.3-6.8. The deposit of the ferrous cake obtained from the first cleaning stage is extracted from the process, and the deposit of the ferrous cake obtained from the second cleaning stage is returned into the process at the initial stage and then again transferred to the solution.

EFFECT: lower nickel losses during cleaning off iron from nickel sulphate solution; higher degree of purity of the nickel sulphate solution; reduction of iron content requirements for the raw materials and a cheaper method.