METHOD OF PREPARING NICKEL NITRATE AQUEOUS SOLUTION Russian patent published in 1997 - IPC

FIELD: waste disposal. SUBSTANCE: in a method of producing nickel nitrate with particle size not larger than 1 mm from worked out nickel oxide catalyst, catalyst is fired in stationary bed at 600 V and 1200 C for 1 to 3 h in gaseous reductive atmosphere in presence of solid, powdered, low-sulfur fuel at catalyst to fuel weight ratio (85-96):(4- 15). Resulting product is cooled in reductive atmosphere to 30-80 C and leached with 30-60% nitric acid at liquid to solids ratio (2-4):1 for 1 to 3 h, followed by filtration, washing out with desalted water, separating solid residue, combining filtrate with wash water, and evaporation to nickel content 100-200 g/l. Target product is finally separated and liquid phase is returned into combination stage. EFFECT: optimized parameters of process. 5 cl, 1 tbl