Patent ID: 7964165
Filing Date: 2011-06-21
Classification: C01G,C22B,Y02P

Abstract:
1. A separation method for zinc sulfide in a hydrometallurgical process by a high pressure acid leach for nickel oxide ore comprising: (a) a leaching and solid/liquid separation step in which sulfuric acid is added to a slurry of nickel oxide ore, leaching is conducted under high temperature and high pressure, then a leach residue is separated while the leaching slurry is subjected to a multistage washing, to obtain a leach liquor containing impurity elements as well as nickel and cobalt; (b) a neutralization step in which pH of the leach liquor is adjusted and a neutralized precipitate containing impurity elements is separated, to obtain a neutralization final liquid containing zinc as well as nickel and cobalt; (c) a zinc removal step in which zinc sulfide is formed by adding a hydrogen sulfide gas to the neutralization final liquid and the zinc sulfide is separated, to obtain a mother liquid for nickel recovery containing nickel and cobalt; and (d) a nickel recovery step in which mixed sulfide containing nickel and cobalt are formed by adding a hydrogen sulfide gas to the mother liquid for nickel recovery, and said mixed sulfide is separated, wherein the leach residue is added to the leach liquor and pH of the neutralization final liquid is adjusted so as to fall in the range from 3.0 to 3.5 in the neutralization step, and that a suspended solid comprising said neutralized precipitate and said leach residue is kept in the neutralization final liquid so that the turbidity thereof falls in the range from 100 to 400 NTU in the zinc removal step.