Method for producing nickel powder

Abstract

Provided is a production method for maintaining the quality while keeping a high operating rate of the reaction by continuously feeding a solution, seed crystals, and hydrogen gas into a reactor to produce nickel powder, and continuously discharging the resulting powder. The method for producing nickel powder comprises feeding a nickel ammine sulfate complex solution and seed crystals into a reactor, and feeding hydrogen gas into the reactor to subject a nickel complex ion in the nickel ammine sulfate complex solution to a reduction treatment and to thereby produce nickel powder, wherein, in the reduction treatment, while the nickel ammine sulfate complex solution is being continuously fed into the reactor, a temperature inside the reactor is controlled within the range of 150 to 185° C. and the feed rate of hydrogen gas is controlled to maintain an inner pressure of the reactor in the range of 2.5 to 3.5 MPa.

1 . A method of producing nickel powder, comprising feeding a nickel ammine sulfate complex solution and seed crystals into a reactor, and feeding hydrogen gas into the reactor to subject a nickel complex ion in the nickel ammine sulfate complex solution to a reduction treatment and to thereby produce nickel powder having a sulfur grade of lower than 0.01% by weight, wherein
 in the reduction treatment, while the nickel ammine sulfate complex solution containing polyacrylic acid in a concentration of 0.5 to 1.0 g/liter is being continuously fed into the reactor, a temperature inside the reactor is controlled within a range of 150 to 185° C. and a feed rate of hydrogen gas is controlled to maintain an inner pressure of the reactor in a range of 2.5 to 3.5 MPa to produce a nickel powder slurry containing the nickel powder, and thereafter, when the nickel powder slurry is extracted from the reactor, a feed amount of the nickel ammine sulfate complex solution and the seed crystals and a discharge amount of the nickel powder slurry are adjusted to keep a given amount of the solution in the reactor.   
     
     
         2 . A method of producing nickel powder, comprising feeding hydrogen gas into a reactor, and feeding a nickel ammine sulfate complex solution and seed crystals into the reactor to subject a nickel complex ion in the nickel ammine sulfate complex solution to a reduction treatment and to thereby produce nickel powder having a sulfur grade of lower than 0.01% by weight, wherein
 in the reduction treatment, the nickel complex ion in the nickel ammine sulfate complex solution is reduced in such a manner that   a slurry containing ammonium sulfate and nickel powder are stored in the reactor to form a liquid phase portion and a gaseous phase portion in the reactor and an inner pressure of the gaseous phase portion is controlled through the feeding of the hydrogen gas into the reactor,   a slurry containing seed crystals and the nickel ammine sulfate complex solution containing polyacrylic acid in a concentration of 0.5 to 1.0 g/liter are continuously fed into the liquid phase portion,   a temperature inside the reactor is controlled in a range of 150 to 185° C., and   a feed rate of the hydrogen gas is controlled to maintain an inner pressure of the reactor in a range of 2.5 to 3.5 MPa   
       to produce a nickel powder slurry containing the nickel powder, and thereafter, when the nickel powder slurry is extracted from the reactor, a feed amount of the nickel ammine sulfate complex solution and the seed crystals and a discharge amount of the nickel powder slurry are adjusted to keep a given amount of the solution in the reactor. 
     
     
         3 . (canceled) 
     
     
         4 . The method of producing nickel powder according to  claim 2 , wherein nickel powder having an average particle size in a range of 0.1 to 100 μm is used as the seed crystals. 
     
     
         5 . The method of producing nickel powder according to  claim 2 , wherein nickel powder having an average particle size in a range of 0.1 to 10 μm is used as the seed crystals. 
     
     
         6 . The method of producing nickel powder according to  claim 5 , wherein an amount of the seed crystals to be added is in a range of 1 to 100% by weight based on a weight of nickel contained in the nickel ammine sulfate complex solution. 
     
     
         7 . The method of producing nickel powder according to  claim 6 , wherein the nickel ammine sulfate complex solution subjected to the reduction treatment contains polyacrylic acid in an amount in a range of 0.5 to 5% by weight based on a weight of the seed crystals in the nickel ammine sulfate complex solution. 
     
     
         8 . The method of producing nickel powder according to  claim 7 , wherein in the reduction treatment, the nickel ammine sulfate complex solution containing the seed crystals is continuously fed into the reactor such that a reaction time of the reduction treatment in the reactor takes 5 to 120 minutes. 
     
     
         9 . The method of producing nickel powder according to  claim 1 , wherein nickel powder having an average particle size in a range of 0.1 to 100 μm is used as the seed crystals. 
     
     
         10 . The method of producing nickel powder according to  claim 1 , wherein nickel powder having an average particle size in a range of 0.1 to 10 μm is used as the seed crystals. 
     
     
         11 . The method of producing nickel powder according to  claim 1 , wherein an amount of the seed crystals to be added is in a range of 1 to 100% by weight based on a weight of nickel contained in the nickel ammine sulfate complex solution. 
     
     
         12 . The method of producing nickel powder according to  claim 1 , wherein the nickel ammine sulfate complex solution subjected to the reduction treatment contains polyacrylic acid in an amount in a range of 0.5 to 5% by weight based on a weight of the seed crystals in the nickel ammine sulfate complex solution. 
     
     
         13 . The method of producing nickel powder according to  claim 1 , wherein in the reduction treatment, the nickel ammine sulfate complex solution containing the seed crystals is continuously fed into the reactor such that a reaction time of the reduction treatment in the reactor takes 5 to 120 minutes.