Hydrometallurgical process for nickel oxide ore

Abstract

Provided is a hydrometallurgical process for nickel oxide ore using high pressure acid leaching to be capable of achieving improvement of durability of production facilities, simplification of the production facilities, suppression of the cost and environmental risks caused by compression of the volume of a tailings dam that stores wastes, and separation and recovery of impurity components which can be utilized as a resource. The hydrometallurgical process for nickel oxide ore of recovering nickel and cobalt using the high pressure acid leaching is characterized by including at least one step selected from step (A) (a step of separating and recovering chromite particles), step (B-1) (a step of neutralizing a leachate with a magnesium-based neutralizing agent), and step (B-2) (a step of neutralizing a leach residue slurry with the magnesium-based neutralizing agent).

1 . A hydrometallurgical process for nickel oxide ore of recovering nickel and cobalt using a high pressure acid leaching that 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, the process comprising at least one step selected from the following step (A), step (B-1), and step (B-2):
 Step (A): separating and recovering chromite particles in an ore slurry produced in the ore processing step, by a recovery process including a specific gravity separation;   Step (B-1): neutralizing a leachate with a magnesium-based neutralizing agent, the leachate being produced by subjecting the ore slurry that has a chromium grade lowered through the step (A), to the leaching step and the solid-liquid separation step; and   Step (B-2): neutralizing a leach residue slurry with a magnesium-based neutralizing agent to recover hematite particles, the leach residue slurry being produced by subjecting the ore slurry that has a chromium grade lowered through the step (A), to the leaching step and the solid-liquid separation step.   
     
     
         2 . A hydrometallurgical process for nickel oxide ore of recovering nickel and cobalt from nickel oxide ore using a high pressure acid leaching that 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, the process comprising the following step (A), step (B-1), and step (B-2):
 Step (A): separating and recovering chromite particles in an ore slurry produced in the ore processing step, by a recovery process including a specific gravity separation;   Step (B-1): neutralizing a leachate with a magnesium-based neutralizing agent, the leachate being produced by subjecting the ore slurry that has a chromium grade lowered through the step (A), to the leaching step and the solid-liquid separation step; and   Step (B-2): neutralizing a leach residue slurry with a magnesium-based neutralizing agent to recover hematite particles, the leach residue slurry being produced by subjecting the ore slurry that has a chromium grade lowered through the step (A), to the leaching step and the solid-liquid separation step.   
     
     
         3 . The hydrometallurgical process for nickel oxide ore of  claim 2 , wherein the recovery process of the step (A) includes subjecting the ore slurry to cyclone classification, reducing fine iron hydroxide particles, and then recovering chromite particles in the ore slurry from the ore slurry as a concentrate of chromite using the specific gravity separation. 
     
     
         4 . The hydrometallurgical process for nickel oxide ore of  claim 3 , wherein the recovery process of the step (A) includes performing cyclone classification without diluting a slurry concentration of the ore slurry. 
     
     
         5 . The hydrometallurgical process for nickel oxide ore of  claim 2 , wherein the recovery process of the step (A) includes collecting chromite into an underflow in cyclone classification in the entire amount except for unavoidable losses. 
     
     
         6 . The hydrometallurgical process for nickel oxide ore of  claim 2 , wherein the specific gravity separation includes at least one step of selected from a step of using a density separator and a step of using a spiral concentrator. 
     
     
         7 . The hydrometallurgical process for nickel oxide ore of  claim 6 , wherein the step of using the density separator is performed two times or more on the slurry concentrated, using the density separator. 
     
     
         8 . The hydrometallurgical process for nickel oxide ore of  claim 6 , wherein the step of using the spiral concentrator is performed two times or more on the slurry concentrated, using the spiral concentrator. 
     
     
         9 . The hydrometallurgical process for nickel oxide ore of  claim 6 , wherein a pulp content of the slurry supplied to the spiral concentrator is 15 wt % solids to 35 wt % solids. 
     
     
         10 . The hydrometallurgical process for nickel oxide ore of  claim 6 , wherein an amount of teeter water supplied to the density separator is 0.5 to 7.0 [m 3 ·h −1 /m 2 ]. 
     
     
         11 . The hydrometallurgical process for nickel oxide ore of  claim 2 , wherein after the specific gravity separation, the slurry is subjected to a magnetic separation, which is a physical separation, to remove magnetite so as to recover non-magnetized material as a chromite concentrate. 
     
     
         12 . The hydrometallurgical process for nickel oxide ore of  claim 2 , wherein in the step (B-2), a pH of the leach residue slurry neutralized is adjusted to be in a range of 4 to 7, and final neutralization is then carried out using an alkali other than a magnesium-based neutralizing agent. 
     
     
         13 . The hydrometallurgical process for nickel oxide ore of  claim 2 , wherein in the step (B-2), the leach residue slurry or a neutralized residue slurry including the leach residue slurry is subjected to cyclone classification, and a fine particle portion thus classified is recovered as a concentrate of hematite. 
     
     
         14 . The hydrometallurgical process for nickel oxide ore of  claim 2 , wherein the ore processing step is a step of performing removal of foreign material in mined raw material ore and adjustment of a particle size of the ore to form ore slurry;
 the leaching step is a step of adding sulfuric acid to the ore slurry and stirring the mixture at a high temperature and a high pressure to form a leached slurry composed of a leach residue and the leachate;   the solid-liquid separation step is a step of washing the leached slurry in multiple stages to obtain the leachate containing nickel and cobalt, and the 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 in 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 in hydrogen sulfide into the mother liquor for nickel and cobalt recovery, and producing a mixed sulfide containing nickel and cobalt, and a barren liquor; and   the final neutralization step is a step of adding an excess of the barren liquor to the leach residue slurry and adjusting the pH of the mixture to be in a range of 8 to 9, to obtain a final neutralized residue.   
     
     
         15 . The hydrometallurgical process for nickel oxide ore of  claim 2 , wherein adjustment of a particle size of the ore in the ore processing step is carried out by screening to a particle size of 2 mm or less. 
     
     
         16 . The hydrometallurgical process for nickel oxide ore of  claim 2 , wherein a grade of chromium(III) oxide in concentrated chromite is 41 wt % or more. 
     
     
         17 . The hydrometallurgical process for nickel oxide ore of  claim 1 , wherein the recovery process of the step (A) includes subjecting the ore slurry to cyclone classification, reducing fine iron hydroxide particles, and then recovering chromite particles in the ore slurry from the ore slurry as a concentrate of chromite using the specific gravity separation. 
     
     
         18 . The hydrometallurgical process for nickel oxide ore of  claim 1 , wherein the recovery process of the step (A) includes collecting chromite into an underflow in cyclone classification in the entire amount except for unavoidable losses. 
     
     
         19 . The hydrometallurgical process for nickel oxide ore of  claim 1 , wherein the specific gravity separation includes at least one step of selected from a step of using a density separator and a step of using a spiral concentrator. 
     
     
         20 . The hydrometallurgical process for nickel oxide ore of  claim 1 , wherein the ore processing step is a step of performing removal of foreign material in mined raw material ore and adjustment of a particle size of the ore to form ore slurry;
 the leaching step is a step of adding sulfuric acid to the ore slurry and stirring the mixture at a high temperature and a high pressure to form a leached slurry composed of a leach residue and the leachate;   the solid-liquid separation step is a step of washing the leached slurry in multiple stages to obtain the leachate containing nickel and cobalt, and the 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 in 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 in hydrogen sulfide into the mother liquor for nickel and cobalt recovery, and producing a mixed sulfide containing nickel and cobalt, and a barren liquor; and   the final neutralization step is a step of adding an excess of the barren liquor to the leach residue slurry and adjusting the pH of the mixture to be in a range of 8 to 9, to obtain a final neutralized residue.