# US 10,500,644 B2 · Method for producing nickel powder having low carbon concentration and low sulfur concentration

> Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt

- Number: US 10,500,644 B2
- Document ID: US10500644B2
- Status: Granted
- Kind: B2
- Application number: 15/303,557
- Filed: 2015-04-13
- Published: 2017-02-16
- Granted: 2019-12-10
- Earliest claimed: 2014-04-15
- Assignees: Sumitomo Metal Mining Co., Ltd.
- Applicants: Sumitomo Metal Mining Co., Ltd.
- Inventors: Yoshitomo Ozaki; Shin-ichi Heguri; Kazuyuki Takaishi; Osamu Ikeda; Hideki Ohara; Tomoaki Yoneyama; Yohei Kudo
- Web page: https://patentgrep.com/patent/US10500644B2

## CPC

- B22F 9/26: using gaseous reductors
- B22F 1/00: Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
- B22F 9/24: starting from liquid metal compounds, e.g. solutions
- C22C 19/03: based on nickel
- B22F 2009/245: {Reduction reaction in an Ionic Liquid [IL]}
- B22F 2301/15: Nickel or cobalt
- B22F 2998/10: Processes characterised by the sequence of their steps
- B22F 2999/00: Aspects linked to processes or compositions used in powder metallurgy
- B22F: WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER (making alloys by powder metallurgy C22C); APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- C22C: ALLOYS (treatment of alloys C21D, C22F)

## Abstract

Provided a production method for reducing the content level of sulfur and carbon which are impurities in nickel powder to improve the quality of nickel powder produced by a complexing reduction method. The method of producing nickel powder having low carbon and sulfur concentrations includes: a complexing treatment of adding a complexing agent to a nickel sulfate aqueous solution to form a solution containing nickel complex ions; maintaining the solution containing nickel complex ions at a solution temperature of 150 to 250° C. in a pressure vessel and blowing hydrogen gas into the solution containing nickel complex ions to perform hydrogen reduction to produce nickel powder; washing the nickel powder with water; and then roasting the nickel powder washed with water in a mixed gas atmosphere of nitrogen and hydrogen.

## Claims

### Claim 1

A method of producing nickel powder having low carbon and sulfur concentrations, the method sequentially comprising:
a complexing treatment of adding a complexing agent to a nickel sulfate aqueous solution to prepare a solution containing nickel complex ions;
a hydrogen reduction treatment of charging the solution containing nickel complex ions in a pressure vessel, maintaining the solution at a solution temperature of 150 to 250° C., and blowing hydrogen gas into the solution containing nickel complex ions to perform hydrogen reduction to produce nickel powder;
a water-washing treatment of washing the nickel powder with water of which amount is at least equal to and at most 5 times larger than a weight of the nickel powder at a solution temperature of 50 to 90° C., or of subjecting a mixture of the nickel powder and water to ultrasonic washing at atmospheric pressure or below, to thereby produce nickel powder having a content level of sulfur reduced by 95% from the content level of sulfur in the nickel powder obtained in the hydrogen reduction treatment and having a content level of carbon reduced by 65% from the content level of the carbon in the nickel powder obtained in the hydrogen reduction treatment; and
a roasting treatment of roasting the nickel powder washed with water in a mixed gas atmosphere of hydrogen having a concentration of 2 to 4% by weight and nitrogen, and thereby causing the content level of the sulfur to be reduced further from the content level of the sulfur obtained in the water-washing treatment and causing the content level of the carbon to be reduced further from the content level of the carbon obtained in the water-washing treatment nickel.

### Claim 2 (depends on 1)

The method of producing nickel powder having low carbon and sulfur concentrations according to claim 1, wherein a temperature during the roasting treatment is 700° C. or more and 1250° C. or less.

### Claim 3 (depends on 1)

The method of producing nickel powder having low carbon and sulfur concentrations according to claim 1, wherein the roasting treatment is carried out so that the content level of sulfur is reduced by at least 50% from the content level of sulfur in the nickel powder obtained in the water-washing treatment and so that the content level of carbon is reduced by at least 29% from the content level of carbon in the nickel powder obtained in the water-washing treatment.

### Claim 4 (depends on 1)

The method of producing nickel powder having low carbon and sulfur concentrations according to claim 1, wherein the roasting treatment is carried out so that the content level of sulfur is reduced by at least 75% from the content level of sulfur in the nickel powder obtained in the water-washing treatment and so that the content level of carbon is reduced by at least 71% from the content level of carbon in the nickel powder obtained in the water-washing treatment.