METHOD OF NICKEL RECOVERY FROM SPENT ALKALI SOLUTIONS OF ELECTROLESS NICKEL Russian patent published in 2001 - IPC

FIELD: methods of purification of spent process solutions from nickel ions; applicable in nickel recovery from spent alkali solutions of electroless nickel plating containing ammonia. SUBSTANCE: as purification from nickel of solutions containing ammonia presents a special problem, because nickel in presence of ammonia forms strong soluble complexes. Claimed method includes gradual heating of initial solution with addition of catalyst in the form of finely dispersed nickel powder produced by decomposition of nickel oxalate in calcination and continuous stirring. In the course of reaction, hydrogen evolves actively and large crystalline precipitate of metallic nickel falls out. Optimal parameters of reaction are the following: solution temperature is 60-70 C, 1-2 g of catalyst per one liter of solution at pH 7.5-8. Purity of precipitated nickel powder of 99-99.8% makes it possible to use it in electroplating or metallurgy. EFFECT: production of metallic nickel of high purity with reduced expenses for process of its recovery from solution and higher process rate. 3 cl, 1 ex