Method for removing radioactive element thorium in rare earth mineral

Patent metadata

Field	Value
Publication number	US-10711324-B2
Application number	US-201716300565-A
Country	US
Kind code	B2
Filing date	Jul 5, 2017
Priority date	Jun 16, 2017
Publication date	Jul 14, 2020
Grant date	Jul 14, 2020

Abstract

The present invention relates to a method for removing radioactive element thorium in a rare earth mineral, comprising: mixing the rare earth mineral with selenium dioxide in water, reacting radioactive element thorium with selenium dioxide by hydrothermal method, cooling to form a crystal, and separating the crystal to remove the radioactive element thorium. In the invention, tetravalent element thorium is selectively bound to inorganic ligand selenium dioxide in a hydrothermal environment to form a crystal, thereby achieving removal of radioactive element thorium. The method has high crystallization rate and high decontamination efficiency, and removes thorium from trivalent lanthanide element by crystallization solidification under a uniform reaction condition. Compared to a conventional industrial method for thorium separation, the method has low energy consumption and high separation ratio, enables one-step solidification separation, and effectively avoids the disadvantages of redundant separation operations and a large amount of organic and radioactive liquid wastes.

First claim

What is claimed is:

1. A method for removing radioactive element thorium in monazite, comprising steps of:
mixing the monazite with selenium dioxide in water,
reacting the radioactive element thorium in the monazite with selenium dioxide by a hydrothermal method,
cooling a resulting solution to form a crystal, and
separating the crystal to remove the radioactive element thorium.

2. The method as claimed in claim 1 , wherein the hydrothermal method includes performing the reaction at 200-230° C. for 1-3 days.

3. The method as claimed in claim 1 , wherein the resulting solution is cooled to room temperature after the reaction is completed.

4. The method as claimed in claim 2 , wherein the cooling rate is 4-10° C./h.

5. The method as claimed in claim 1 , further comprising a step of washing the crystal after separating the crystal.

6. The method as claimed in claim 5 , wherein the crystal is washed with water, alcohol and dilute nitric acid.

7. The method as claimed in claim 6 , wherein the dilute nitric acid has a mass concentration of 5-10%.

8. The method as claimed in claim 1 , wherein the crystal is a needle-like and flocculent crystal.

Assignees

• Univ Soochow

Inventors

• Wang Shuao
• Lu Huangjie
• Wang Yaxing

Classifications

• C01B19/008 Primary

  Salts of oxyacids of selenium or tellurium · CPC title

• Y02P10/20

  Recycling · CPC title

• C30B7/10

  by application of pressure, e.g. hydrothermal processes · CPC title

• C30B29/46

  Sulfur-, selenium- or tellurium-containing compounds · CPC title

• C30B29/10

  Inorganic compounds or compositions · CPC title