Method for producing nickel powder

Abstract

A nickel sulfate amine complex liquid and nickel powder having a particle diameter of 0.1 m to 300 m are supplied to a reaction container, hydrogen gas is continuously supplied while the inside of the reaction container is maintained at 150 C. to 250 C., and the pressure is set to 2.5 MPa to 3.5 MPa, whereby nickel ions in the nickel sulfate amine complex liquid are reduced to nickel and deposited on the surfaces of the nickel powder supplied to the reaction container, a reacted slurry including the nickel sulfate amine complex liquid and the nickel powder is then transferred to a pressurized storage container at the same or slightly lower pressure than the internal pressure of the reaction container, and the pressure of the pressurized storage container to which the reacted slurry is transferred is then reduced, after which the reacted slurry is extracted from the pressurized storage container.

Claims

1. A method for producing nickel powder, the method comprising: supplying a nickel sulfate ammine complex solution and nickel powder having a particle size of 0.1 m to 300 m as seed crystals to a reaction container, continuously supplying hydrogen gas to set a pressure of a gas phase part inside the reaction container to 2.5 MPa to 3.5 MPa while the inside of the reaction container is maintained at a temperature in a range of 150 C. to 250 C. so that nickel ions in the nickel sulfate ammine complex solution are reduced to nickel and the reduced nickel is precipitated on a surface of the nickel powder as seed crystals supplied to the reaction container so as to obtain reduced nickel powder; subsequently transferring a reacted slurry containing the nickel sulfate ammine complex solution and the reduced nickel powder to a pressurized storage container which is connected to the reaction container and is maintained at the same as an internal pressure of the reaction container or lower than the internal pressure of the reaction container by a range of 0.2 MPa to 1.0 MPa; and subsequently reducing the pressure of the pressurized storage container to which the reacted slurry is transferred, and then extracting the reacted slurry from the pressurized storage container to recover the reduced nickel powder.

2. The method for producing nickel powder according to claim 1, wherein the internal pressure of the pressurized storage container is adjusted and maintained by blowing an inert gas to the pressurized storage container to increase the pressure of the pressurized storage container or discharging the inert gas from the pressurized storage container to reduce the pressure of the pressurized storage container.

3. The method for producing nickel powder according to claim 1, wherein the internal pressure of the pressurized storage container is reduced by cooling the inside of the pressurized storage container to 100 C. or lower.

4. The method for producing nickel powder according to claim 1, wherein the internal pressure of the pressurized storage container to which the reacted slurry is transferred is reduced to atmospheric pressure, the reacted slurry is then extracted from the pressurized storage container, and the extracted reacted slurry is subjected to solid-liquid separation to recover the nickel powder.

5. The method for producing nickel powder according to claim 2, wherein the internal pressure of the pressurized storage container is reduced by cooling the inside of the pressurized storage container to 100 C. or lower.

6. The method for producing nickel powder according to claim 2, wherein the internal pressure of the pressurized storage container to which the reacted slurry is transferred is reduced to atmospheric pressure, the reacted slurry is then extracted from the pressurized storage container, and the extracted reacted slurry is subjected to solid-liquid separation to recover the nickel powder.

Description

EXAMPLES

(1) Hereinafter, the present invention will be described in more detail by means of Examples of the present invention, but the present invention is not limited to the following Examples at all.

Example 1

(2) In a reaction container (pressurized container) using an autoclave with an inner capacity of 190 L, 90 L of a solution composed of 362 g/L of ammonium sulfate and 100 g/L of nickel powder was charged, the reaction container was tightly sealed, and then the temperature in the reaction container was increased to 185 C. and maintained. Then, hydrogen gas was blown to a gas phase part of the reaction container so that the internal pressure of the gas phase part thereof was adjusted to 2.5 MPa and maintained.

(3) Further, a charging port of a receiving vessel with a capacity of 580 L was connected to a discharge valve of a discharge port of the reaction container, nitrogen gas was caused to pass through the inside of the receiving vessel to replace the inside of the receiving vessel with air, and then the internal pressure of the receiving vessel was increased to 2.0 MPa and maintained.

(4) Then, a nickel sulfate ammine complex solution with a nickel concentration of 75 g/L and a starting solution composed of ammonium sulfate with a concentration of 330 g/L were continuously added to the reaction container at a rate of 1 L per minute, and a nickel powder slurry with a concentration of 150 g/L using nickel powder with a particle size of 30 m was continuously added to the reaction container at a rate of 0.5 L per minute. Further, hydrogen gas in a cylinder was blown such that the internal pressure of the reaction container was maintained at 2.5 MPa, and thus hydrogen reduction reaction occurred.

(5) The reacted slurry (nickel powder slurry) was transferred to the receiving vessel while the liquid volume of the reaction container was managed in a range of 90 L5 L. Incidentally, this transfer operation was performed for 45 minutes.

(6) Then, a heating medium was caused to flow into a jacket provided at the circumference of the receiving vessel to perform indirect cooling. After receiving the nickel powder slurry, an atmosphere opening valve of the receiving vessel was gradually opened to reduce the pressure to atmospheric pressure, and then the nickel powder slurry was extracted from the receiving vessel.

(7) Incidentally, the temperature of the nickel powder slurry was 56 C. Further, the amount of the nickel powder slurry recovered in the receiving vessel was 65.5 L (1.46 L/min in terms of flow rate) and the slurry concentration of the nickel slurry was 53 g/L.

(8) Then, the obtained nickel powder slurry was subjected to solid-liquid separation using a Nutsche funnel to be separated into the nickel powder (reduced nickel powder) and the reacted nickel sulfate ammine complex solution. The average particle size of the nickel powder obtained by separating and recovering in this way was 75 m. Further, after completion of the reaction in the reaction container, the discharge valve or piping of the reaction container and the inside of the receiving vessel were observed, and as a result, abrasion, damage, or the like was not observed.

Comparative Example 1

(9) In Comparative example 1, similarly to Example 1, nickel powder was grown by using a nickel sulfate ammine complex solution, nickel powder as seed crystals, and hydrogen gas, and then the grown nickel powder was transferred to a receiving vessel connected to a reaction container. At this time, the internal pressure of the receiving vessel was set to the same as atmospheric pressure.

(10) After completion of the reaction in the reaction container, the discharge valve or piping of the reaction container and the inside of the receiving vessel were observed, as a result, abrasion caused by the generated nickel powder, damage in the inner wall caused by collision of the nickel powder, or the like was observed, so that it was determined that the reaction container does not withstand against use application over a long period time thereafter.