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

• US 10,280,482 B2
• Filed: 06/16/2016
• Issued: 05/07/2019
• Est. Priority Date: 06/16/2015
• Status: Active Grant

• Current Assignee: Grirem Advanced Materials Co., Ltd.
• Original Assignee: Grirem Advanced Materials Co., Ltd.
• Inventors: Huang, Xiaowei, Xu, Yang, Wang, Jinyu, Wang, Liangshi, Feng, Zongyu, Cui, Dali, Long, Zhiqi, Sun, Xu, Zhao, Na
• Primary Examiner(s): Bos, Steven J
• Application Number:
  US15/736,874
• Publication Number:
  US 20180363098A1
• Time in Patent Office: 1,055 Days
• Field of Search: 423 211, 423132, 423324
• CPC Class Codes: C01F 17/10 Preparation or treatment, e.g. separation or purification
• CPC Class Codes: C01F 17/206 oxide or hydroxide being the only anion
• CPC Class Codes: C01F 17/271 Chlorides
• CPC Class Codes: C01F 17/276 Nitrates
• CPC Class Codes: C01F 7/04 Preparation of alkali metal aluminates; Aluminium oxide or hydroxide therefrom C01F7/028 takes precedence
• CPC Class Codes: C01F 7/0693 from waste-like raw materials, e.g. fly ash or Bayer calcination dust
• CPC Class Codes: C01F 7/22 with halides or halogen acids
• CPC Class Codes: C01F 7/24 with nitric acid or nitrogen oxides
• CPC Class Codes: C01F 7/26 with sulfuric acids or sulfates
• CPC Class Codes: C22B 21/0023 from waste materials
• CPC Class Codes: C22B 3/44 by chemical processes treatment or purification of solutions by liquid-liquid extraction C22B3/26, by ion-exchange extraction C22B3/42
• CPC Class Codes: C22B 59/00 Obtaining rare earth metals
• CPC Class Codes: C22B 7/00 Working up raw materials other than ores, e.g. scrap, to produce non-ferrous metals and compounds thereof; Methods of a general interest or applied to the winning of more than two metals briquetting of scrap C22B1/248; preliminary treatment of scrap C22B1/005
• CPC Class Codes: C22B 7/007 by acid leaching
• CPC Class Codes: Y02P 10/20 Recycling

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.

Claims

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 step of primary recovery of aluminum in the rare earth-containing aluminum silicon scrap occurs 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 a obtain sodium metaaluminate solution and the rare earth-containing aluminum silicon scrap after the primary recovery of aluminum.

24. The method according to claim 23, wherein in the step of primary recovery, a molar ratio of the sodium hydroxide to aluminum atoms in the rare earth-containing aluminum silicon scrap is 1:

1˜

3;

1, and the rare earth-containing aluminum silicon scrap is reacted with the sodium hydroxide at 20˜

120°

C. for 0.5˜

8 hours.

25. The method according to claim 22, wherein extraction and purification is performed for the rare earth salt solution.