Method of recovering rare earth aluminum and silicon from rare earth-containing aluminum-silicon scraps

Patent metadata

Field	Value
Publication number	US-10280482-B2
Application number	US-201615736874-A
Country	US
Kind code	B2
Filing date	Jun 16, 2016
Priority date	Jun 16, 2015
Publication date	May 7, 2019
Grant date	May 7, 2019

Abstract

Disclosed is a method of recovering rare earth, aluminum and silicon from rare earth-containing aluminum-silicon scrap. The method comprises: S1, acid-leaching the rare earth-containing aluminum-silicon scrap with an inorganic acid aqueous solution to obtain a silicon-rich slag and acid leached solution containing rare earth and aluminum element; S2, adding an alkaline substance into the acid leached solution containing the rare earth and aluminum element and controlling a PH value of the acid leaching solution between 3.5 to 5.2, performing a solid-liquid separation to obtain a aluminum hydroxide-containing precipitate and a rare earth-containing solution filter; S3, reacting the aluminum hydroxide containing precipitate with sodium hydroxide to obtain sodium metaaluminate solution and aluminum-silicon slag, and preparing a rare earth compound product with the rare earth-containing filtrate. The method dissolves an the aluminum and the rare earth with the acid and then via step wise alkaline conversion, convert aluminum icons to an aluminum hydroxide precipitate separated from rare earth ions, and then adds excessive amounts of sodium hydroxide to convert the aluminum hydroxide to a sodium metaaluminate solution, thereby realizing high-efficiency recovery of both rare earth and aluminum while significantly reducing the consumption of the sodium hydroxide and thus recovery cost.

First claim

What is claimed is:

1. A method of recovering and reusing rare earth, aluminum and silicon from a rare earth-containing aluminum silicon scrap, wherein the method comprises steps of:
S1, acid-leaching the rare earth-containing aluminum silicon scrap with an inorganic acid aqueous solution, to obtain a silicon-rich slag and an acid leaching solution containing rare earth and aluminum elements;
S2, adding an alkaline substance to the acid leaching solution containing rare earth and aluminum elements, controlling an end-point pH value of the acid leaching solution between 3.5 and 5.2 to obtain a slurry, and performing solid-liquid separation for the slurry to obtain an aluminum hydroxide-containing precipitate and a rare earth-containing filtrate; and
S3, reacting the aluminum hydroxide-containing precipitate with sodium hydroxide to obtain a sodium metaaluminate solution and an aluminum silicon slag, and preparing a rare earth compound product with the rare earth-containing filtrate.

2. The method according to claim 1 , wherein in the step S1, a pH value during reaction is controlled to be 0.1˜2.5.

3. The method according to claim 1 , wherein in the step S1, a temperature of the acid-leaching is 10˜80° C., and an end-point pH value of the acid leaching solution containing rare earth and aluminum obtained is 0.5˜2.0.

4. The method according to claim 3 , wherein in the step S1, the inorganic acid aqueous solution is sulfuric acid solution, hydrochloric acid solution or nitric acid solution.

5. The method according to claim 1 , wherein in the step S2, the alkaline substance is added to the acid leaching solution containing rare earth and aluminum in the manner of stirring to perform a precipitation reaction, the precipitation reaction lasts for 0.5˜8 hours at 10˜60° C., and the end-point pH value of the precipitation reaction is 4.0˜4.8.

6. The method according to claim 1 , wherein in the step S3, a molar ratio of the sodium hydroxide added to aluminum atoms in the aluminum hydroxide-containing precipitate is 1:1˜3:1; and the aluminum hydroxide-containing precipitate is reacted with the sodium hydroxide at 20˜120° C. for 0.5˜8 hours.

7. The method according to claim 1 , wherein in the step S3, preparing the rare earth compound product with the rare earth-containing filtrate comprises:
performing extraction-separation for the rare earth-containing filtrate to obtain a rare earth-carried organic phase and a raffinate;
performing reverse extraction for the rare earth-carried organic phase with hydrochloric acid or nitric acid to obtain a chloride rare earth solution or a nitric acid rare earth solution; or
adding the alkaline substance to the rare earth-containing filtrate, and controlling a pH value of the rare earth-containing filtrate to be 6.0˜9.5 to obtain a rare earth precipitate and a scrap liquid.

8. The method according to claim 7 , wherein an extractant used in the extraction-separation is P507, P204, or a naphthenic acid; the extractant is diluted with a diluent, and a volume content of the extractant in the extractant diluted is 10˜60%.

9. The method according to claim 7 , wherein adding the alkaline substance to the rare earth-containing filtrate in a manner of stirring at a temperature of 10˜60° C. to react for 0.5˜8 hours, and controlling the pH value of the rare earth-containing filtrate to be 7.0˜9.0 to obtain the rare earth precipitate and the scrap liquid.

10. The method according to claim 1 , wherein the alkaline substance is one or more of an organic alkaline substance or an inorganic alkaline substance; the inorganic alkaline substance is a soluble carbonate, a soluble bicarbonate, a soluble hydroxide or an ammonia water.

11. The method according to claim 10 , wherein the inorganic alkaline substance is at least one of sodium hydroxide, sodium carbonate and sodium bicarbonate.

12. The method according to claim 1 , wherein when a mass ratio of aluminum to silicon is more than 1:1 in the rare earth-containing aluminum silicon scrap, a step of primary recovery of aluminum in the rare earth-containing aluminum silicon scrap is added before the step S1, and the step of primary recovery comprises: reacting the rare earth-containing aluminum silicon scrap with sodium hydroxide, performing solid-liquid separation to obtain a sodium metaaluminate solution and the rare earth-containing aluminum silicon scrap after the primary recovery of aluminum.

13. The method according to claim 12 , wherein a molar ratio of the sodium hydroxide to aluminum atoms in the rare earth-containing aluminum silicon scrap is 1:1˜3:1 for reacting the rare earth-containing aluminum silicon scrap with sodium hydroxide at 20˜120° C. for 0.5˜8 hours.

14. A method of recovering rare earth, aluminum and silicon from rare earth-containing aluminum silicon scrap, wherein the method comprises:
S1, acid-leaching the rare earth-containing aluminum silicon scrap with an inorganic acid aqueous solution, to obtain a silicon-rich slag and an acid leaching solution containing rare earth and aluminum elements;
S2, adding an alkaline substance to the acid leaching solution containing rare earth and aluminum elements, controlling an end-point pH value of the acid leaching solution between 6.0 and 9.5 to obtain a mixed precipitate of rare earth hydroxide and aluminum hydroxide after filtering; and
S3, reacting the mixed precipitate of rare earth hydroxide and aluminum hydroxide with sodium hydroxide to obtain a sodium metaaluminate solution and a rare earth hydroxide precipitate.

15. The method according to claim 14 , wherein in the step S1, a pH value during reaction is controlled to be 0.1˜2.5.

16. The method according to claim 14 , wherein in the step S1, a temperature of the acid-leaching is 10˜80° C., and an end-point pH value of the acid leaching solution containing rare earth and aluminum obtained is 0.5˜2.0.

17. The method according to claim 16 , wherein in the step S1, the inorganic acid aqueous solution is sulfuric acid solution, hydrochloric acid solution or nitric acid solution.

18. The method according to claim 14 , wherein in the step S2, adding the alkaline substance to the acid leaching solution containing rare earth and aluminum elements in the manner of stirring at a temperature of 10˜60° C. to react for 0.5˜8 hours, controlling the end-point pH value of the acid leaching solution between 7.0 and 9.0.

19. The method according to claim 14 , wherein the alkaline substance is one or more of an organic alkaline substance or an inorganic alkaline substance; the inorganic alkaline substance is a soluble carbonate, a soluble bicarbonate, a soluble hydroxide or an ammonia water.

20. The method according to claim 19 , wherein the inorganic alkaline substance is at least one of sodium hydroxide, sodium carbonate, and sodium bicarbonate.

21. The method according to claim 14 , wherein in the step S3, a molar ratio of the sodium hydroxide added to aluminum atoms in the aluminum hydroxide-containing precipitate is 1:1—3:1; and the aluminum hydroxide-containing precipitate is reacted with the sodium hydroxide at 20˜120° C. for 0.5˜8 hours.

22. The method according to claim 14 , wherein in the step S3, the rare earth hydroxide precipitate is dissolved by hydrochloric acid, nitric acid, or sulfuric acid to obtain a rare earth salt solution.

23. The method according to claim 14 , wherein when a mass ratio of aluminum to silicon is more than 1:1 in the rare earth-containing aluminum silicon scrap, a st

Assignees

• Grirem Advanced Mat Co Ltd

Inventors

• Huang Xiaowei
• Xu Yang
• Wang Jinyu
• Wang Liangshi
• Feng Zongyu
• Cui Dali
• Long Zhiqi
• Sun Xu
• Zhao Na

Classifications

• C01F17/10

  Preparation or treatment, e.g. separation or purification · CPC title

• C01F17/206

  oxide or hydroxide being the only anion · CPC title

• C01F17/276

  Nitrates · CPC title

• C01F17/271

  Chlorides · CPC title

• C01F7/0693

  from waste-like raw materials, e.g. fly ash or Bayer calcination dust · CPC title