Method for recovering rare earth element

Patent metadata

Field	Value
Publication number	US-2016108498-A1
Application number	US-201414893611-A
Country	US
Kind code	A1
Filing date	May 29, 2014
Priority date	May 31, 2013
Publication date	Apr 21, 2016
Grant date	—

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

1 . A method for recovering a rare earth element, comprising subjecting a workpiece containing at least a rare earth element and an iron group element to an oxidation treatment, then turning the treatment environment into an environment where carbon is present, and subjecting an oxidation-treated workpiece to a heat treatment, thereby separating a rare earth element in the form of an oxide from an iron group element,
the method being characterized in that in the heat treatment of the 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.

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

• C22B7/001

  Dry processes · CPC title

• C22B59/00 Primary

  Obtaining rare earth metals · CPC title

• C22B1/00

  Preliminary treatment of ores or scrap · CPC title

• C01G1/02

  Oxides · CPC title

• Y02P10/20

  Recycling · CPC title