# US 12,179,214 B2 · Extracting rare-earth elements from a gangue heavy fraction

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- Number: US 12,179,214 B2
- Document ID: US12179214B2
- Status: Granted
- Kind: B2
- Application number: 16/903,871
- Filed: 2020-06-17
- Published: 2021-01-07
- Granted: 2024-12-31
- Earliest claimed: 2016-10-31
- Assignees: Georgia State University Research Foundation, Inc.; Thiele Kaolin Company
- Applicants: Georgia State University Research Foundation; Thiele Kaolin Company
- Inventors: W. Crawford Elliott; Daniel Joseph Gardner; Ed Riley; Prakash Malla
- Web page: https://patentgrep.com/patent/US12179214B2

## CPC

- B03B 9/00: General arrangement of separating plant, e.g. flow sheets
- B03B 5/30: using heavy liquids or suspensions
- C22B 1/00: Preliminary treatment of ores or scrap
- C22B 59/00: Obtaining rare earth metals
- B03B: SEPARATING SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS
- C22B: PRODUCTION AND REFINING OF METALS (electrolytic C25); PRETREATMENT OF RAW MATERIALS

## Abstract

Described herein are technologies for concentrating rare-earth elements from a heavy fraction of grit in gangue produced in kaolin mining. In some examples, grit is separated as a non-clay fraction of gangue produced in a kaolin mining operation. The grit is separated into a heavy mineral grit sub-fraction and a light mineral grit sub-fraction. Rare-earth elements, particularly heavy rare-earth elements, are thereafter extracted from the heavy mineral grit sub-fraction using various extraction technologies.

## Claims

### Claim 1

A method of concentrating a rare-earth element, the method comprising:
receiving crude clay from a mining operation of a kaolin-bearing formation;
separating the crude clay into a grit and a kaolin clay fraction, wherein the grit is gangue from the mining operation;
separating the grit fraction into a light mineral grit sub-fraction and a heavy mineral grit sub-fraction; and
concentrating the rare-earth element from the heavy mineral grit sub-fraction.

### Claim 2 (depends on 1)

The method of claim 1, wherein separating the crude clay into the grit fraction and the kaolin clay fraction comprises:
crushing the crude clay and mixing the crushed, crude clay with water and a dispersant; and
screening the grit using a 325 mesh sieve (44 microns) to produce the grit fraction, the grit fraction comprising a coarse silt fraction and a sand fraction.

### Claim 3 (depends on 2)

The method of claim 2, wherein the dispersant comprises sodium hexametaphosphate solution.

### Claim 4 (depends on 1)

The method of claim 1, wherein the silt fraction comprises particles ranging in size from 2 microns to 62.5 microns or from 3.9 microns to 50 microns.

### Claim 5 (depends on 1)

The method of claim 1, wherein separating the grit fraction into the light mineral grit sub-fraction and the heavy mineral grit sub-fraction comprises placing the grit fraction into a heavy liquid solution having a defined density to cause a fractionation of the grit concentration into the light mineral grit sub-fraction and the heavy mineral grit sub-fraction, wherein the rare-earth element is present in the heavy mineral grit sub-fraction.

### Claim 6 (depends on 5)

The method of claim 5, wherein mineral grains with densities greater than 2.95 Kg/L settle to the bottom of the heavy liquid solution and mineral grains with densities less than 2.95 Kg/L floated to the top of the heavy liquid solution.

### Claim 7 (depends on 5)

The method of claim 5, wherein the heavy liquid comprises lithium metatungstate (LMT).

### Claim 8 (depends on 5)

The method of claim 5, wherein the heavy liquid comprises at least one of bromoform, tetrabromoethane (TBE), sodium polytungstate, or LMT Heavy Liquid.

### Claim 9 (depends on 1)

The method of claim 1, wherein concentrating the rare-earth element from the heavy mineral grit sub-fraction comprises performing a thermal treatment of the heavy mineral grit sub-fraction or acid baking of the heavy mineral grit sub-fraction.

### Claim 10 (depends on 9)

The method of claim 9, wherein the rare-earth element comprises cerium (Ce), dysprosium (Dy), erbium (Er), europium (Eu), gadolinium (Gd), holmium (Ho), lanthanum (La), lutetium (Lu), neodymium (Nd), praseodymium (Pr), promethium (Pm), samarium (Sm), scandium (Sc), terbium (Tb), thulium (Tm), ytterbium (Yb) or yttrium (Y).

### Claim 11 (depends on 1)

The method of claim 1, wherein the gangue is produced from a mining operation in the Buffalo Creek Formation.

### Claim 12 (depends on 1)

The method of claim 1, wherein the gangue is produced from a mining operation in the Jeffersonville Member of the Huber Formation.

### Claim 13 (depends on 1)

The method of claim 1, wherein the gangue is produced from a mining operation of the Primary deposits.

### Claim 14 (depends on 1)

The method of claim 1, wherein the gangue is produced from a mining operation of the Secondary deposits.

### Claim 15 (depends on 1)

The method of claim 1, wherein the gangue is produced from a mining operation of the Sedimentary deposits.

### Claim 16 (depends on 1)

The method of claim 1, wherein separating the grit fraction into the light mineral grit sub-fraction and the heavy mineral grit sub-fraction is performed using a centrifugal separation.