METHOD OF ISOLATION OF NICKEL SULFATE Russian patent published in 1997 - IPC

FIELD: chemical technology, inorganic chemistry. SUBSTANCE: invention relates to nickel sulfate production from the spent sulfate electrolytes of refined copper production. Method involves the combined evaporation-crystallization of decoppering solution after copper electrorefining at ratio Fe:Cu = (1.5-3.0):1, under vacuum 1.96-9.81 kPa, dissolving nickel sulfate in mixture of return mother liquor and condensate taken at ratio = 1: (2-4), carbonization of heated nickel sulfate solution with calcium carbonate to pH = 4.5-6.5 by bubbling suspension with compressed air at 70-80 C in mixture followed by carbonate precipitate filtering off. Then the purified filtrate is fed to the repeated combined evaporation-crystallization under the same vacuum value and continuous circulation of suspension up to solid: liquid = 1: (2.5-4.0) and recrystallization of the removed nickel sulfate suspension at stirring, at 40-45 C. Method ensures to obtain large-crystalline nickel sulfate hexahydrate of $$$-modification. Extraction of nickel to crystalline product is increased up to 50-56%, total yield of nickel in salt - 86-90%. Phase composition and an average crystal diameter 0.9-1.2 mm provide retention of friability of nickel sulfate for above 1 year. EFFECT: improved method of isolation. 3 cl, 1 tbl