Hydrometallurgical process for nickel oxide ore

Abstract

Provided is a hydrometallurgical process for nickel oxide ore for recovering nickel and cobalt using a high pressure acid leach process, the process achieving simplification and durability improvement of production facilities, achieving cost reduction and suppression of environmental risk by the compression of the capacity of a tailings dam for storing wastes, and being capable of recycling and effectively utilizing the wastes as a resource. The hydrometallurgical process for nickel oxide ore for recovering nickel and cobalt using a high pressure acid leach process includes an ore processing step, a leaching step, a solid-liquid separation step, a neutralization step, a zinc removal step, a sulfurization step, and a final neutralization step, and further includes step (A), or further includes step (A) and, step (B- 1 ) and/or step (B- 2 ) after step (A).

What is claimed is: 
     
         1 . A hydrometallurgical process for nickel oxide ore for recovering nickel and cobalt using a high pressure acid leach process comprising an ore processing step, a leaching step, a solid-liquid separation step, a neutralization step, a zinc removal step, a sulfurization step, and a final neutralization step, the hydrometallurgical process further comprising,
 step (A): a step of separating chromite particles from an ore slurry produced in the ore processing step by a recovery process including specific gravity separation, and then classifying the chromite particles to recover a high-concentration chromite concentrate having a grade of chromium(III) oxide of at least more than 50% by weight.   
     
     
         2 . The hydrometallurgical process for nickel oxide ore according to  claim 1 , wherein the chromite concentrate separated by the specific gravity separation is subjected to magnetic separation which is a physical separation to remove magnetite from the chromite concentrate as a magnetic material and recover a non-magnetic material as a high-concentration chromite concentrate. 
     
     
         3 . The hydrometallurgical process for nickel oxide ore according to  claim 1 , wherein
 the ore processing step is a step of performing removal of foreign matter from mined raw ore and particle size adjustment of the ore to form an ore slurry;   the leaching step is a step of adding sulfuric acid to the ore slurry and stirring a resulting mixture at high temperature and high pressure to form a leach slurry composed of a leach residue and a leachate;   the solid-liquid separation step is a step of subjecting the leach slurry to multi-stage washing to obtain a leachate containing nickel and cobalt and a leach residue slurry;   the neutralization step is a step of adding an alkali to the leachate to form a neutralized precipitate slurry containing trivalent iron and a mother liquor for nickel recovery;   the zinc removal step is a step of blowing hydrogen sulfide gas into the mother liquor to form a zinc sulfide precipitate slurry and a mother liquor for nickel and cobalt recovery;   the sulfurization step is a step of blowing hydrogen sulfide into the mother liquor for nickel and cobalt recovery to produce a mixed sulfide containing nickel and cobalt and a barren liquor; and   the final neutralization step is a step of adding excess of the barren liquor to the leach residue slurry and adjusting pH to 8 to 9 to obtain a final neutralized residue.