# US 10,865,463 B2 · Useful method for separating light rare earth elements and heavy rare earth elements

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- Number: US 10,865,463 B2
- Document ID: US10865463B2
- Status: Granted
- Kind: B2
- Application number: 15/754,700
- Filed: 2016-08-25
- Published: 2018-08-30
- Granted: 2020-12-15
- Earliest claimed: 2015-08-26
- Assignees: Hitachi Metals, Ltd.
- Applicants: Hitachi Metals, Ltd.
- Inventors: Hiroyuki Hoshi
- Web page: https://patentgrep.com/patent/US10865463B2

## CPC

- C22B 59/00: Obtaining rare earth metals
- C01F 17/10: Preparation or treatment, e.g. separation or purification
- C22B 3/065: {Nitric acids or salts thereof}
- C22B 3/10: Hydrochloric acid {, other halogenated acids or salts thereof}
- C22B 3/20: Treatment or purification of solutions, e.g. obtained by leaching (C22B3/18 takes precedence)
- C22B 3/44: by chemical processes (treatment or purification of solutions by liquid-liquid extraction C22B3/26, by ion-exchange extraction C22B3/42)
- C22B 7/007: {by acid leaching}
- Y02P 10/20: Recycling
- C22B: PRODUCTION AND REFINING OF METALS (electrolytic C25); PRETREATMENT OF RAW MATERIALS
- C01F: COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS (metal hydrides {monoborane, diborane or addition complexes thereof} C01B6/00; salts of oxyacids of halogens C01B11/00; peroxides, salts of peroxyacids C01B15/00; sulfides or polysulfides of magnesium, calcium, strontium, or barium C01B17/42; thiosulfates, dithionites, polythionates C01B17/64; compounds containing selenium or tellurium C01B19/00; binary compounds of nitrogen with metals C01B21/06; azides C01B21/08; {compounds other than ammonia or cyanogen containing nitrogen and non-metals and optionally metals C01B21/082; amides or imides of silicon C01B21/087}; metal {imides or} amides C01B21/092, {C01B21/0923}; nitrites C01B21/50; {compounds of noble gases C01B23/0005}; phosphides C01B25/08; salts of oxyacids of phosphorus C01B25/16; carbides C01B32/90; compounds containing silicon C01B33/00; compounds containing boron C01B35/00; compounds having molecular sieve properties but not having base-exchange properties C01B37/00; compounds having molecular sieve and base-exchange properties, e.g. crystalline zeolites, C01B39/00; cyanides C01C3/08; salts of cyanic acid C01C3/14; salts of cyanamide C01C3/16; thiocyanates C01C3/20; {double sulfates of magnesium with sodium or potassium C01D5/12; with other alkali metals C01D15/00, C01D17/00})
- Y02P: CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS

## Abstract

A method for separating a light rare earth element and a heavy rare earth element includes at least the steps of: (1) obtaining, from a workpiece containing a light rare earth element and a heavy rare earth element, a composite oxide or mixture of oxides of the two; (2) dissolving the obtained composite oxide or mixture of oxides in hydrochloric acid and/or nitric acid; (3) adding a precipitant to the obtained solution to give a precipitate; (4) calcining the obtained precipitate; (5) adding the obtained calcine in an amount of 1.1 times to 3.0 times the upper solubility limit to hydrochloric acid and/or nitric acid having a concentration of 0.7 mol/L or more to give a solution and a residue; and (6) separating the obtained solution and residue, thereby giving the solution as a light rare earth element-rich inclusion and the residue as a heavy rare earth element-rich inclusion.

## Claims

### Claim 1

A method for obtaining a light rare earth element-rich inclusion and a heavy rare earth element-rich inclusion from a composite oxide of the light rare earth element and the heavy rare earth element or a mixture of an oxide of the light rare earth element and an oxide of the heavy rare earth element in order to separate the two, characterized by including at least:
(1) a step of dissolving a composite oxide of the light rare earth element and the heavy rare earth element or a mixture of an oxide of the light rare earth element and an oxide of the heavy rare earth element in hydrochloric acid and/or nitric acid;
(2) a step of adding a precipitant to the obtained solution to give a precipitate;
(3) a step of calcining the obtained precipitate;
(4) a step of adding the obtained calcine in an amount of 1.1 times to 3.0 times the upper solubility limit to hydrochloric acid and/or nitric acid having a concentration of 0.7 mol/L or more to give a solution and a residue; and
(5) a step of separating the obtained solution and residue, thereby giving the solution as a light rare earth element-rich inclusion and the residue as a heavy rare earth element-rich inclusion, wherein the term “rich” means that the content ratio of the concerned rare earth element to the other rare earth element is higher than the content ratio in the composite oxide of the light rare earth element and the heavy rare earth element or the mixture of an oxide of the light rare earth element and an oxide of the heavy rare earth element.

### Claim 2

A method for obtaining a light rare earth element-rich inclusion and a heavy rare earth element-rich inclusion from a workpiece containing a light rare earth element and a heavy rare earth element in order to separate the two, characterized by including at least:
(1) a step of obtaining, from a workpiece containing a light rare earth element and a heavy rare earth element, a composite oxide of the light rare earth element and the heavy rare earth element or a mixture of an oxide of the light rare earth element and an oxide of the heavy rare earth element;
(2) a step of dissolving the obtained composite oxide of the light rare earth element and the heavy rare earth element or the mixture of an oxide of the light rare earth element and an oxide of the heavy rare earth element in hydrochloric acid and/or nitric acid;
(3) a step of adding a precipitant to the obtained solution to give a precipitate;
(4) a step of calcining the obtained precipitate;
(5) a step of adding the obtained calcine in an amount of 1.1 times to 3.0 times the upper solubility limit to hydrochloric acid and/or nitric acid having a concentration of 0.7 mol/L or more to give a solution and a residue; and
(6) a step of separating the obtained solution and residue, thereby giving the solution as a light rare earth element-rich inclusion and the residue as a heavy rare earth element-rich inclusion, wherein the term “rich” means that the content ratio of the concerned rare earth element to the other rare earth element is higher than the content ratio in the workpiece.

### Claim 3 (depends on 2)

The method according to claim 2, characterized in that at least one member selected from oxalic acid, acetic acid, and a metal salt of carbonic acid is used as the precipitant.

### Claim 4 (depends on 2)

The method according to claim 2, characterized in that the workpiece is an R—Fe—B based permanent magnet.

### Claim 5 (depends on 2)

The method according to claim 2, characterized in that the content ratio between the light rare earth element and the heavy rare earth element contained in the workpiece, wherein the content ratio is defined as the weight of the heavy rare earth element/the weight of the light rare earth element, is 0.05 to 0.50.

### Claim 6 (depends on 2)

The method according to claim 2, characterized in that the content ratio between a light rare earth element and a heavy rare earth element contained in the solution that serves as a light rare earth element-rich inclusion, wherein the content ratio is defined as the concentration of the heavy rare earth element/the concentration of the light rare earth element, is 0.02 to 0.05, and the content ratio is 0.01 or more smaller than the content ratio between the light rare earth element and the heavy rare earth element contained in the workpiece.