Method for producing nickel powder

Abstract

Provided is a method for manufacturing coarse particles of a so-called high-purity nickel powder with a small amount of impurities, particularly having a low sulfur grade, from a nickel sulfate amine complex solution using a fine nickel powder. A method for manufacturing a nickel powder includes the following treatment steps (1) to (6) in a process for manufacturing a nickel powder from a nickel sulfate solution: (1) a hydroxylation step; (2) a complexation step; (3) a reduction step; (4) a solid/liquid separation step; (5) a nickel recovery step of repeatedly supplying the recovered nickel powder to step (2) and/or step (3), sulfurating the recovered final reduction solution, and then solid/liquid separating the sulfurated solution to generate nickel sulfide and a nickel post-reduction solution; and (6) a nickel regeneration step of oxidatively leaching the nickel sulfide obtained in step (5) and repeatedly supplying the obtained nickel sulfate solution to step (1).

1 . A method for manufacturing a nickel powder from a nickel sulfate solution, comprising:
 (1) a hydroxylation step of adding an alkali to the nickel sulfate solution to generate a precipitate of nickel hydroxide;   (2) A complexation step of adding a final reduction solution obtained from a solid/liquid separation step (4) and a nickel powder as a seed crystal to the precipitate of nickel hydroxide generated in the hydroxylation step (1), and dissolving the precipitate of the nickel hydroxide to form a mixed slurry containing a nickel sulfate amine complex solution, the seed crystal, and the nickel hydroxide;   (3) a reduction step of blowing a hydrogen gas into the mixed slurry formed in the complexation step (2) to form a reduced slurry containing a nickel powder formed by precipitation of a nickel component in the mixed slurry on the seed crystal;   (4) a solid/liquid separation step of solid/liquid separating the reduced slurry formed in the reduction step (3) and recovering a nickel powder and a final reduction solution;   (5) a nickel recovery step of repeatedly supplying the recovered nickel powder to either or both of the complexation step (2) and the reduction step (3), adding a sulfurizing agent to the recovered final reduction solution, precipitating nickel sulfide, and subjecting it to solid/liquid separation to generate nickel sulfide and a nickel post-reduction solution; and   (6) a nickel regeneration step of oxidatively leaching the nickel sulfide obtained in the nickel recovery step (5) and repeatedly supplying the obtained nickel sulfate solution to the hydroxylation step (1).   
     
     
         2 . The method for manufacturing a nickel powder according to  claim 1 , wherein
 sieving the nickel powder recovered in the solid/liquid separation step (4) according to a particle size, selecting a nickel powder having a smaller size than a predetermined particle size, and adding the selected nickel powder to the complexation step (2) and/or the reduction step (3) as a seed crystal are repeatedly performed to obtain a nickel powder having a larger particle size than the nickel powder as the seed crystal.   
     
     
         3 . The method for manufacturing a nickel powder according to  claim 2 , wherein
 the seed crystal added in either or both of the complexation step (2) and the reduction step (3) has an average particle size of 0.1 to 100 μm.   
     
     
         4 . The method for manufacturing a nickel powder according to  claim 1 , wherein
 when the mixed slurry containing a nickel sulfate amine complex solution, a seed crystal, and nickel hydroxide is formed in the complexation step (2), a dispersant is further added to the mixed slurry.   
     
     
         5 . The method for manufacturing a nickel powder according to  claim 1 , wherein
 the seed crystal is added in an amount of 1 to 100% with respect to a weight of nickel in the nickel sulfate amine complex solution in the complexation step (2).   
     
     
         6 . The method for manufacturing a nickel powder according to  claim 1 , wherein
 the reduced slurry is sieved, and the sieved nickel powder and the sieved reduced slurry as a final reduction solution are repeatedly used as a part of the final reduction solution and the nickel powder as a seed crystal in the complexation step (2).   
     
     
         7 . The method for manufacturing a nickel powder according to  claim 6 , wherein
 the complexation step (2) includes two steps of
 a dissolving step of adding a final reduction solution to obtain a nickel sulfate amine complex solution, and 
 a seed crystal adding step of adding a nickel powder or a mixed slurry containing a nickel powder and a final reduction solution. 
   
     
     
         8 . The method for manufacturing a nickel powder according to  claim 1 , wherein
 the nickel sulfate solution is obtained by dissolving at least one selected from a mixed sulfide of nickel and cobalt recovered by leaching nickel oxide ore, nickel sulfide, crude nickel sulfate, nickel oxide, nickel hydroxide, nickel carbonate, and a nickel metal powder, in a sulfuric acid acidic solution.   
     
     
         9 . The method for manufacturing a nickel powder according to  claim 1 , wherein
 the nickel sulfate solution is obtained through
 a leaching step of dissolving a nickel-containing material containing cobalt as impurities, and 
 a solvent extraction step of adjusting a pH of a leachate containing nickel and cobalt obtained in the leaching step and then separating the leachate into a nickel sulfate solution and a cobalt recovery solution by a solvent extraction method. 
   
     
     
         10 . The method for manufacturing a nickel powder according to  claim 1 , wherein
 an ammonium sulfate concentration in the nickel sulfate amine complex solution is 100 to 500 g/L, and an ammonium concentration is 1.9 or more in a molar ratio with respect to a nickel concentration in the complex solution.   
     
     
         11 . The method for manufacturing a nickel powder according to  claim 1 , wherein
 blowing of a hydrogen gas performed while a temperature is maintained in a range of 100 to 200° C. and a pressure is maintained in a range of 0.8 to 4.0 MPa in the reduction step (3).   
     
     
         12 . The method for manufacturing a nickel powder according to  claim 4 , wherein
 the dispersant contains a polyacrylate.   
     
     
         13 . The method for manufacturing a nickel powder according to  claim 1 , further comprising:
 a nickel powder briquetting step of processing the nickel powder obtained through the reduction step (3) into a massive nickel briquette using a briquetting machine; and   a briquette sintering step of sintering the obtained massive nickel briquette in a hydrogen atmosphere under a holding condition of a temperature of 500 to 1200° C. to form a nickel briquette as a sintered body.   
     
     
         14 . The method for manufacturing a nickel powder according to  claim 1 , further comprising
 an ammonium sulfate recovery step of concentrating the final reduction solution in the solid/liquid separation step (4), crystallizing ammonium sulfate, and recovering an ammonium sulfate crystal.   
     
     
         15 . The method for manufacturing a nickel powder according to  claim 1 , further comprising
 an ammonia recovery step of adding an alkali to the final reduction solution in the solid/liquid separation step (4), heating the resulting mixture, volatilizing an ammonia gas, and recovering ammonia.