Provided is a method for producing nickel powder from a nickel ammine sulfate complex solution, comprising treatment steps of: (1) a seed crystal production step of producing nickel powder having an average particle size of 0.1 to 5 m; (2) a seed crystal addition step of adding the nickel powder obtained in the step (1) as seed crystals to form a mixed slurry; (3) a reduction step of forming a reduced slurry containing nickel powder formed by precipitation of a nickel component in the mixed slurry on the seed crystals; and (4) a growth step of performing solid-liquid separation to separate and recover the nickel powder as a solid phase component and then blowing hydrogen gas into a solution prepared by adding the nickel ammine sulfate complex solution to the recovered nickel powder to grow the nickel powder to form high purity nickel powder.

Provided is a method for producing nickel powder from a nickel ammine sulfate complex solution, comprising treatment steps of: (1) a seed crystal production step of producing nickel powder having an average particle size of 0.1 to 5 m; (2) a seed crystal addition step of adding the nickel powder obtained in the step (1) as seed crystals to form a mixed slurry; (3) a reduction step of forming a reduced slurry containing nickel powder formed by precipitation of a nickel component in the mixed slurry on the seed crystals; and (4) a growth step of performing solid-liquid separation to separate and recover the nickel powder as a solid phase component and then blowing hydrogen gas into a solution prepared by adding the nickel ammine sulfate complex solution to the recovered nickel powder to grow the nickel powder to form high purity nickel powder.

The present invention includes a partially continuous countercurrent process for converting gypsum, by reaction with ammonium carbonate, to products of ammonium sulfate and calcium carbonate by introducing the reactants into reactors, mixing the reactants for a predetermined amount of time, employing a novel combination of countercurrent flows coupled with the reactors operated in a batch manner with process recycle of liquids, removing materials from the reactor and separating solids from solutions wherein no reactants are added during the removal process and thus the reactants have sufficient time to react and ensure the desired degree of reaction, yield and purity of product calcium carbonate and ammonium sulfate while minimizing the reaction time.

The present invention includes a partially continuous countercurrent process for converting gypsum, by reaction with ammonium carbonate, to products of ammonium sulfate and calcium carbonate by introducing the reactants into reactors, mixing the reactants for a predetermined amount of time, employing a novel combination of countercurrent flows coupled with the reactors operated in a batch manner with process recycle of liquids, removing materials from the reactor and separating solids from solutions wherein no reactants are added during the removal process and thus the reactants have sufficient time to react and ensure the desired degree of reaction, yield and purity of product calcium carbonate and ammonium sulfate while minimizing the reaction time.

Provided is a method for producing nickel powder from a nickel ammine sulfate complex solution, comprising treatment steps of: (1) a seed crystal production step of producing nickel powder having an average particle size of 0.1 to 5 m; (2) a seed crystal addition step of adding the nickel powder obtained in the step (1) as seed crystals to form a mixed slurry; (3) a reduction step of forming a reduced slurry containing nickel powder formed by precipitation of a nickel component in the mixed slurry on the seed crystals; and (4) a growth step of performing solid-liquid separation to separate and recover the nickel powder as a solid phase component and then blowing hydrogen gas into a solution prepared by adding the nickel ammine sulfate complex solution to the recovered nickel powder to grow the nickel powder to form high purity nickel powder.

Provided is a method for producing nickel powder from a nickel ammine sulfate complex solution, comprising treatment steps of: (1) a seed crystal production step of producing nickel powder having an average particle size of 0.1 to 5 m; (2) a seed crystal addition step of adding the nickel powder obtained in the step (1) as seed crystals to form a mixed slurry; (3) a reduction step of forming a reduced slurry containing nickel powder formed by precipitation of a nickel component in the mixed slurry on the seed crystals; and (4) a growth step of performing solid-liquid separation to separate and recover the nickel powder as a solid phase component and then blowing hydrogen gas into a solution prepared by adding the nickel ammine sulfate complex solution to the recovered nickel powder to grow the nickel powder to form high purity nickel powder.