Method for producing R-Fe-B based permanent magnet alloy recycled material having removed carbon

Patent metadata

Field	Value
Publication number	US-9657367-B2
Application number	US-201214125715-A
Country	US
Kind code	B2
Filing date	Jun 29, 2012
Priority date	Jun 30, 2011
Publication date	May 23, 2017
Grant date	May 23, 2017

Abstract

An object of the present invention is to provide a method for producing an alloy recycled material by effectively removing carbon from a carbon-containing alloy, which is produced as scrap or sludge of an R—Fe—B based permanent magnet, a used magnet, or the like. The method of the present invention as a means for resolution is characterized in that a carbon-containing R—Fe—B based permanent magnet alloy is subjected to an HDDR treatment to remove carbon. An alloy recycled material produced by the method of the present invention contains a reduced amount of carbon. Therefore, in the case where it is recycled for the production of a magnet, even when an increased amount is subjected to high-frequency heating in a vacuum melting furnace, a non-negligible increase in the amount of carbon contained in the produced magnet can be avoided.

First claim

The invention claimed is:

1. A method for recycling a carbon-containing R—Fe—B based permanent magnet alloy, comprising the steps of:
removing carbon in the carbon-containing R—Fe—B based permanent magnet alloy by subjecting the carbon-containing R—Fe—B based permanent magnet alloy to a Hydrogenation-Disproportionation-Desorption-Recombination treatment, wherein the carbon-containing R—Fe—B based permanent magnet alloy contains a carbon content of 0.04 mass % or more, and
melting by heating an R—Fe—B based permanent magnet alloy from which carbon was removed, wherein a carbon content of the R—Fe—B based permanent magnet alloy from which carbon was removed is 0.03 mass % or less.

2. The method according to claim 1 , characterized in that the carbon-containing R—Fe—B based permanent magnet alloy is in the form of a powder having a particle size of 75 μm to 850 μm.

3. The method according to claim 1 , characterized in that the Hydrogenation-Disproportionation-Desorption-Recombination treatment includes a Hydrogenation and Disproportionation step performed in a hydrogen gas atmosphere at 600° C. to 900° C.

4. The method according to claim 1 , characterized in that the Hydrogenation-Disproportionation-Desorption-Recombination treatment to remove carbon is followed by melting by heating and then solidification by cooling to form a slab or an ingot.

5. The method according to claim 1 , characterized in that the carbon-containing R—Fe—B based permanent magnet alloy is selected from the group consisting of magnet scrap, magnet sludge and used magnets.

6. A method for producing an R—Fe—B based permanent magnet, comprising the steps of:
removing carbon in a carbon-containing R—Fe—B based permanent magnet alloy by subjecting the carbon-containing R—Fe—B based permanent magnet alloy to a Hydrogenation-Disproportionation-Desorption-Recombination treatment, wherein the carbon-containing R—Fe—B based permanent magnet alloy contains a carbon content of 0.04 mass % or more, and
melting by heating an R—Fe—B based permanent magnet alloy from which carbon was removed as at least a part of raw materials for producing an R—Fe—B based permanent magnet, wherein a carbon content of the R—Fe—B based permanent magnet alloy from which carbon was removed is 0.03 mass % or less.

Assignees

• Furusawa Katsuyoshi
• Kikugawa Atsushi
• Hitachi Metals Ltd

Inventors

• Furusawa Katsuyoshi
• Kikugawa Atsushi

Classifications

• B22F8/00 Primary

  Manufacture of articles from scrap or waste metal particles · CPC title

• C22B7/001

  Dry processes · CPC title

• Y02W30/541

  Cross-Sectional Technologies · mapped topic

• C22B59/00

  Obtaining rare earth metals · CPC title

• H01F41/0253

  for manufacturing permanent magnets · CPC title