Process for metallurgy and separating rare earth concentrate using combination method

Patent metadata

Field	Value
Publication number	US-2021310100-A1
Application number	US-201917267481-A
Country	US
Kind code	A1
Filing date	Aug 9, 2019
Priority date	Aug 10, 2018
Publication date	Oct 7, 2021
Grant date	—

Abstract

The present invention provides a process for metallurgy and separating a rare earth concentrate using a combination method, the process including: treating the rare earth concentrate containing bastnaesite by using a method including roasting under an atmosphere, leaching with hydrochloric acids, and roasting with a sulfuric acid, wherein stepping acid leaching with low-concentration hydrochloric acids is controlled during the leaching with the hydrochloric acids so as to obtain a rare earth solution with a high concentration (150-250 g/L REO), such that a leaching rate of Ce reaches 60% or more, and the content of F − in a leaching liquor is reduced by aging; and rare earth is further recovered from a leach residue by roasting with the sulfuric acid and leaching with water, and the total yield of the rare earth reaches 95% or more.

First claim

1 . A process for metallurgy and separating a rare earth concentrate using a combination method, the process comprising:
(1) decomposing the rare earth concentrate by roasting under a certain roasting atmosphere to obtain a roasted concentrate; (2) adding the roasted concentrate with a hydrochloric acid to leach rare earth, and collecting a leaching liquor of rare earth and a leach residue respectively after solid-liquid separation; and (3) dehydrating the leach residue, then adding the dehydrated leach residue with a concentrated sulfuric acid, roasting, collecting a roasted product, leaching the roasted product with water, and neutralizing to remove impurities to obtain a rare earth sulfate solution.

2 . The process for metallurgy and separating the rare earth concentrate using the combination method according to claim 1 , wherein in step (1), the roasting atmosphere during the roasting comprises one or more of water vapor, air, CO, and CO2.

3 . The process for metallurgy and separating the rare earth concentrate using the combination method according to claim 1 , wherein in step (1), the roasting is at a roasting temperature of 350° C. to 650° C.

4 . The process for metallurgy and separating the rare earth concentrate using the combination method according to claim 1 , wherein in step (2), the leaching with the hydrochloric acid preferably comprises two or more steps of countercurrent leaching with hydrochloric acids, wherein in the first step, solid-liquid separation is performed after leaching with the hydrochloric acid to obtain a first-step leaching liquor of rare earth and a first-step leach residue, and next, the first-step leach residue is leached with the hydrochloric acid, and solid-liquid separation is performed to obtain a second-step leaching liquor of rare earth and a second-step leach residue, wherein the second-step leaching liquor of the rare earth is returned to be used as bottom water for leaching with the hydrochloric acid in the previous step, and next, the second-step leach residue is leached with the hydrochloric acid.

5 . The process for metallurgy and separating the rare earth concentrate using the combination method according to claim 1 , wherein in step (2), the hydrochloric acids are added in the way that 2 to 5 stages of continuous cocurrent leaching are carried out during the leaching, and hydrochloric acids are controlled to be added in a concentration gradient during each stage of leaching to keep the acidity of a mixed solution at 0.01 mol/L to 0.6 mol/L during the leaching.

6 . The process for metallurgy and separating the rare earth concentrate using the combination method according to claim 1 , wherein in step (2), a leaching temperature during the leaching with the hydrochloric acids is controlled to be 10° C. to 75° C.

7 . The process for metallurgy and separating the rare earth concentrate using the combination method according to claim 1 , wherein in step (3), a mass ratio (w/w) of the concentrated sulfuric acid to the dehydrated leach residue is (0.3 to 1.2): 1.

8 . The process for metallurgy and separating the rare earth concentrate using the combination method according to claim 1 , wherein in step (3), the roasting with the sulfuric acid is at a temperature of 200° C. to 450° C., and the leaching with water is at a temperature of 20° C. to 50° C.

9 . The process for metallurgy and separating the rare earth concentrate using the combination method according to claim 1 , wherein step (3) further comprises: separating the obtained rare earth sulfate solution by extraction, or transforming the obtained rare earth sulfate solution by extraction or transforming the obtained rare earth sulfate solution by precipitation to obtain a rare earth chloride solution; and separating the rare earth chloride solution by extraction to obtain a single rare earth compound.

10 . The process for metallurgy and separating the rare earth concentrate using the combination method according to claim 1 , wherein in step (2), the obtained leaching liquor of the rare earth is aged at 60° C. to 90° C. for 1 to 5 hours, and solid-liquid separation is performed to obtain a rare earth chloride solution and a rare earth fluoride powder product; and the obtained rare earth chloride solution is combined with the rare earth chloride solution obtained by transforming the rare earth sulfate solution in step (3), and separating the combined solution by extraction to obtain a single rare earth compound.

11 . The process for metallurgy and separating the rare earth concentrate using the combination method according to claim 1 , wherein water or an alkaline liquid is sprayed onto fluorine-containing tail gas generated during the roasting in step (1) or defluorination is performed on the fluorine-containing tail gas using one or two adsorbents of a rare earth oxide and a rare earth hydrated oxide to recover a rare earth fluoride product; and sulfur-containing tail gas generated in the roasting with the sulfuric acid in step (3) is desulfurized and recycled to obtain a sulfuric acid product.

12 . The process for metallurgy and separating the rare earth concentrate using the combination method according to claim 2 , wherein in step (1), the roasting is at a roasting temperature of 350° C. to 650° C.

13 . The process for metallurgy and separating the rare earth concentrate using the combination method according to claim 2 , wherein in step (2), the leaching with the hydrochloric acid preferably comprises two or more steps of countercurrent leaching with hydrochloric acids, wherein in the first step, solid-liquid separation is performed after leaching with the hydrochloric acid to obtain a first-step leaching liquor of rare earth and a first-step leach residue, and next, the first-step leach residue is leached with the hydrochloric acid, and solid-liquid separation is performed to obtain a second-step leaching liquor of rare earth and a second-step leach residue, wherein the second-step leaching liquor of the rare earth is returned to be used as bottom water for leaching with the hydrochloric acid in the previous step, and next, the second-step leach residue is leached with the hydrochloric acid.

14 . The process for metallurgy and separating the rare earth concentrate using the combination method according to claim 3 , wherein in step (2), the leaching with the hydrochloric acid preferably comprises two or more steps of countercurrent leaching with hydrochloric acids, wherein in the first step, solid-liquid separation is performed after leaching with the hydrochloric acid to obtain a first-step leaching liquor of rare earth and a first-step leach residue, and next, the first-step leach residue is leached with the hydrochloric acid, and solid-liquid separation is performed to obtain a second-step leaching liquor of rare earth and a second-step leach residue, wherein the second-step leaching liquor of the rare earth is returned to be used as bottom water for leaching with the hydrochloric acid in the previous step, and next, the second-step leach residue is leached with the hydrochloric acid.

15 . The process for metallurgy and separating the rare earth concentrate using the combination method according to claim 2 , wherein in step (2), the hydrochloric acids are added in the way that 2 to 5 stages of continuous cocurrent leaching are carried out during the leaching, and hydrochloric acids are controlled to be added in a concentration gradient during each stage of leaching to keep the acidity of a mixed solution at 0.01 mol/L to 0.6 mol/L during the leaching.

16 . The process for metallurgy and separating th

Assignees

• Grirem Advanced Mat Co Ltd

Inventors

• Huang Xiaowei
• Feng Zongyu
• Sun Xu
• Xu Yang
• Wang Meng
• Wang Liangshi
• Xia Chao
• Liu Xiangsheng
• Zhao Longsheng
• Zhang Yongqi

Classifications

• C22B1/02 Primary

  Roasting processes (C22B1/16 takes precedence) · CPC title

• C22B1/06

  Sulfating roasting · CPC title

• C22B3/10

  Hydrochloric acid {, other halogenated acids or salts thereof} · CPC title

• C22B59/00 Primary

  Obtaining rare earth metals · CPC title

• Y02P10/20

  Recycling · CPC title