Method for recovering rare earth element

Patent metadata

Field	Value
Publication number	US-10023938-B2
Application number	US-201414893611-A
Country	US
Kind code	B2
Filing date	May 29, 2014
Priority date	May 31, 2013
Publication date	Jul 17, 2018
Grant date	Jul 17, 2018

Abstract

An object of the present invention is to provide a method according to which a rare earth element can be efficiently recovered from a workpiece containing at least a rare earth element and an iron group element, and also wear and damage to the treatment container can be suppressed, allowing the container to be used repeatedly for a long period of time. The method of the present invention as a means for resolution is characterized in that in the heat treatment of an oxidation-treated workpiece in the presence of carbon, when the oxidation-treated workpiece is placed in a treatment container, a carbon substance is interposed between the oxidation-treated workpiece and the bottom surface of the container, and the heat treatment is performed in an inert gas atmosphere or in vacuum at a temperature of 1300° C. or more.

First claim

The invention claimed is:

1. A method for recovering a rare earth element, comprising the steps of:
subjecting a workpiece containing at least a rare earth element and an iron group element to an oxidation treatment to produce an oxidation-treated workpiece,
then placing the oxidation-treated workpiece in a treatment container with a carbon substance interposed between the oxidation-treated workpiece and the bottom surface of the container, and
performing a heat treatment in an inert gas atmosphere or in vacuum at a temperature of 1300° C. or more,
thereby separating a rare earth element in the form of an oxide from an iron group element.

2. The method according to claim 1 , characterized in that at least part of the workpiece is in granular or powder form having a particle size of 500 μm or less.

3. The method according to claim 1 , characterized in that the workpiece has an iron group element content of 30 mass % or more.

4. The method according to claim 1 , characterized in that the workpiece is an R—Fe—B based permanent magnet.

5. The method according to claim 1 , characterized in that the oxidation-treated workpiece housed in a housing member made of paper, wood, synthetic resin, or carbon is placed in the treatment container.

6. The method according to claim 1 , characterized in that a carbon substance housed in a housing member made of paper, wood, synthetic resin, or carbon is interposed between the oxidation-treated workpiece and the bottom surface of the container.

7. The method according to claim 1 , characterized in that a carbon substance is further interposed between the oxidation-treated workpiece and the side surface of the container.

8. The method according to claim 7 , characterized in that the carbon substance interposed between the oxidation-treated workpiece and the side surface of the container is partitioned from the oxidation-treated workpiece by a partition member made of paper, wood, synthetic resin, or carbon.

9. The method according to claim 7 , characterized in that a carbon substance housed in a housing member made of paper, wood, synthetic resin, or carbon is interposed between the oxidation-treated workpiece and the side surface of the container.

10. The method according to claim 1 , characterized in that a carbon substance is further placed in the treatment container.

Assignees

• Hitachi Metals Ltd

Inventors

• Hoshi Hiroyuki
• Miyamoto Yu

Classifications

• C21B15/02

  Metallothermic processes, e.g. thermit reduction · CPC title

• C22B1/00

  Preliminary treatment of ores or scrap · CPC title

• C22B59/00 Primary

  Obtaining rare earth metals · CPC title

• C21B11/00

  Making pig-iron other than in blast furnaces · CPC title

• C01G56/007

  Compounds of transuranic elements (C01G56/001 and C01G56/004 take precedence) · CPC title