Patent ID: 8343447
Filing Date: 2013-01-01
Classification: C22B

Abstract:
1. A hydrometallurgical process for a nickel oxide ore comprising: step (1): obtaining an aqueous solution of crude nickel sulfate containing zinc as an impurity element, in addition to nickel and cobalt, by high pressure acid leach of a nickel oxide ore; step (2): obtaining zinc sulfide and a zinc free final solution, by introducing the aqueous solution of crude nickel sulfate into a sulfurization reactor (A), adding hydrogen sulfide gas, sulfurization of zinc contained in said aqueous solution of crude nickel sulfate, and then performing solid-liquid separation; step (3): obtaining a mixed sulfide of nickel/cobalt and a waste solution, by introducing the zinc free final solution into a sulfurization reactor (B), adding hydrogen sulfide gas, sulfurization of nickel and cobalt contained in said zinc free final solution, subsequently introducing a formed slurry into an evaporation apparatus for evaporation of hydrogen sulfide gas, and then performing solid-liquid separation; and step (4): obtaining an exhaust gas scrubbed and a waste solution from a scrubber, by introducing exhaust gas from the sulfurization reactor (A), the sulfurization reactor (B) or the evaporation apparatus into the scrubber, and contacting the exhaust gas with an alkaline aqueous solution for absorption of hydrogen sulfide gas; wherein said process further comprises operation (a): (a) adjust total volume (m and said process optionally comprises one or more operations selected from operations (b), (c) and (d): (b) evaporate under negative pressure hydrogen sulfide gas dissolved in a solution of said slurry in step (3) to recover hydrogen sulfide gas, and add the recovered hydrogen sulfide gas into the sulfurization reactor (B) of (3); (c) reuse the hydrogen sulfide gas containing inert components from said sulfurization reactor (B), wherein the gas is accumulated in the gas phase part thereof, by controlling pressure inside the sulfurization reactor (B) in step (3); and add the gas into the sulfurization reactor (A) of step (2); and (d) subject the waste solution in step (3) and exhaust gas scrubbed in step (4) to countercurrent contact, introduce the resulting exhaust gas to the scrubber again, contact the resulting exhaust gas with the alkaline aqueous solution for absorption of hydrogen sulfide gas, and charge the resulting waste solution from the scrubber into the sulfurization reactor (B) in step (3).