PROCESS FOR RECOVERING METALS FROM COAL LIQUEFACTION RESIDUE CONTAINING SPENT CATALYSTS

• US 20100300250A1
• Filed: 03/25/2010
• Published: 12/02/2010
• Est. Priority Date: 03/25/2009
• Status: Active Grant

• Current Assignee: Chevron USA Incorporated (Chevron Corp.)
• Original Assignee: Chevron USA Incorporated (Chevron Corp.)
• Inventors: Bhaduri, Rahul S.
• Granted Patent: US 8,628,735 B2
• Time in Patent Office: Days
• US Class Current: 75/743
• CPC Class Codes: C22B 3/06 in inorganic acid solutions , e.g. with acids generated in situ; in inorganic salt solutions other than ammonium salt solutions
• 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 34/225 from spent catalysts
• CPC Class Codes: C22B 34/345 from spent catalysts
• CPC Class Codes: C22B 7/006 Wet processes
• CPC Class Codes: C22B 7/009 General processes for recovering metals or metallic compounds from spent catalysts for recovering specific metals C22B11/00 - C22B61/00
• CPC Class Codes: Y02P 10/20 Recycling

Abstract

In one embodiment, this invention is directed to a method of recovering metals from a metals bearing material comprising: reducing the particle size of at least a portion of the metals bearing material; mixing the metals bearing material in an acid solution to form a first slurry containing at least alkaline earth metal compounds; separating the at least alkaline earth metal compounds from the first slurry to form a first filtrate and a metals bearing material; leaching metals from the metals bearing material to form a pressure leach solution containing transition metals; precipitating and recovering transition metals from the pressure leach solution. In another aspect, the invention relates to a method for recovering metals from a deoiled and dried coal liquefaction residue that contains spent catalyst originating from a Group VIB metal sulfide catalyst.

Claims

1. A method of recovering metals from a metals bearing material comprising:

(a) reducing the particle size of at least a portion of the metals bearing material;

(b) mixing the metals bearing material in an acid solution to form a first slurry containing at least alkaline earth metal compounds;

(c) separating the at least alkaline earth metal compounds from the first slurry to form a first filtrate and a metals bearing material;

(d) leaching metals from the metals bearing material to form a pressure leach solution containing transition metals;

(e) precipitating and recovering transition metals from the pressure leach solution.

2. The method of claim 1 wherein step (a) comprises comminution of the metal bearing materials to a particle size passing 200-mesh. at least 70%

3. The method of claim 1 wherein the metals bearing materials comprises inorganic material, ash and a spent catalyst.

4. The method of claim 3 wherein the spent catalyst comprises one or more transition metals selected from the group consisting of Group VIB metals and sulfides thereof.

5. The method of claim 4 wherein the spent catalyst comprises molybdenum.

6. The method of claim 1 wherein the metals bearing material contains about 0.1% to 10% molybdenum by weight.

7. The method of claim 1 wherein the acid solution of step (b) is a weak acid solution selected from the group consisting of weak solutions of is sulfuric acid, nitric acid, hydrochloric acid and phosphoric acid.

8. The method of claim 7 wherein the weak acid solution of step (b) is a water-soluble organic acid selected from the group consisting of formic acid, acetic acid, propionic acid, sulfamic acid and trichloro-acetic acid.

9. The method of claim 1 wherein step (b) is carried out at a temperature 35°

C. and 80°

C. for a time between about 1 to 4 hours.

10. The method of claim 9 wherein at least 70% of the at least alkaline earth metal compounds of step (b) are dissolved.

11. The method of claim 1 wherein the first filtrate of step (c) comprises solubilized alkaline earth metals and materials consisting of ash, insoluble organic matter and spent catalyst.

12. The method of claim 11 wherein the solubilized alkaline earth metals are precipitated from the first filtrate by contacting the first filtrate, in the presence of air, with a phosphate at a pH of about neutral.

13. The method of claim 12 wherein the phosphate is selected from the group consisting of ammonium phosphate, potassium phosphate and sodium phosphate.

14. The method of claim 13 the phosphate strength ranges from about 0.5 to 5.0 normal.

15. The method of claim 1 wherein the metals bearing materials is a coal liquefaction residue.

16. The method of claim 15 wherein the coal liquefaction residue comprises 0.1 to 10% Mo by weight.

17. The method of claim 16 wherein the coal liquefaction residue comprises 40 to 60% by weight insoluble organic matter and is 40 to 60% by weight ash.

18. The method of claim 17 wherein the ash comprises between 1-5 wt. % Al, 1-3 wt. % Ba, 2-10 wt. % Ca, 1-5 wt. % Fe, 1-5 wt. % Na, 3-10 wt. % Si and 40-60 wt. % C.

19. The method of claim 1 wherein step (d) further comprises forming the pressure leach solution in an autoclave in the presence of ammonia and air, at a pressure and a temperature sufficient to produce leaching reactions and forming soluble complexes of Group VIB transition metals.

20. The method of claim 19 wherein step (d) wherein at least 70% of the Group VIB transition metals are leached into solution.

21. The method of claim 20 wherein the Group VIB transition metal is molybdenum and wherein at least 75 wt. % of said molybdenum is leached into solution in the form of ammonium molybdate.

22. The method of claim 19 wherein the pressure and the temperature within the autoclave respectively range between 120°

C. to 250°

C. and from 0 psig to 1200 psig.

23. The method of claim 22 wherein the pressure and the temperature within the autoclave respectively range between 135°

C. to 225°

C. and from 100 psig. to 1000 psig.

24. The method of claim 22 or claim 23 further comprising a leaching time between 60 minutes to 360 minutes.

25. The method of claim 1 wherein step (d) further comprises passing the pressure leach slurry to a liquid solids separation step selected from the group consisting of settling, centrifugation, decantation and filtration to form a pressure leach residue comprising ash and insoluble organic matter and a pressure leach filtrate comprising Group VIB metal complexes and ammonium sulfate.

26. The method of claim 25 wherein the liquid solids separation step comprises filtration by a method selected from the group consisting of vertical centrifugation, vacuum filter, plate and frame filter and pressure belt filter.

27. The method of claim 25 wherein the pressure leach filtrate is passed to an acid precipitation step wherein a strong mineral acid is added to the pressure leach filtrate to achieve a preselected pH to effect precipitation of at least 90% of the Group VIB metals to form a Group VIB metal slurry.

28. The method of claim 27 wherein the preselected pH is 3.5 to effect precipitation of at least 90% of a molybdenum complex contained in said pressure leach filtrate.

29. The method of claim 27 wherein the Group VIB metal precipitated is tungsten and the preselected pH ranges from 1.0 to about 2.0 to effect precipitation of at least 95% of the soluble tungsten complexes.

30. The method of claim 27 wherein the strong mineral acid is selected from the group consisting of sulfuric acid, hydrochloric acid, phosphoric acid and nitric acid.

31. The method of claim 27 wherein the Group VIB metal slurry is passed to a solid liquid separation step selected from the group consisting of settling, filtration, decantation, centrifugation, and combinations thereof to form a Group VIB metals precipitate and an ammonium sulfate filtrate.

32. A method of claim 31 wherein the Group VIB metals precipitate comprises 50 to 80 wt. % molybdenum, not more than one wt. % vanadium, less than 20 wt. % ammonium sulfate and 1 to 10 wt. % sulfur.

33. The method of claim 31 wherein the ammonium sulfate filtrate is substantially free of Group VIB metal complexes.

34. The method of claim 31 wherein the ammonium sulfate filtrate comprises from 0.1 to 3% of the Group VIB metals contained in the metals bearing materials.

35. A method of recovering metals from a spent coal liquefaction catalyst, the method comprising:

(a) withdrawing a coal liquefaction residue from a coal liquefaction process wherein the coal liquefaction residue contains a spent catalyst;

(b) classifying the coal liquefaction residue to a particle size sufficient to pass a 200-mesh sieve to form a spent catalyst residue;

(c) contacting the spent catalyst residue with a weak acid solution to dissolve alkaline earth metal compounds and form a first slurry containing the spent catalyst, ash, insoluble organic matter and dissolved alkaline earth metal complexes;

(d) separating and removing the dissolved alkaline earth metal complexes from the slurry to form a metals bearing materials containing the spent catalyst;

(e) leaching the metals bearing materials containing the spent catalyst with an ammonia solution in the presence of air, at a sufficient temperature and pressure to form a pressure leach slurry containing at least a Group VIB soluble metal complex. insoluble organic matter and ash;

(f) separating and removing the metals bearing materials from the pressure leach slurry to form a pressure leach solution;

(g) precipitating from the pressure leach solution at least a portion of the Group VIB metal, wherein the precipitation is carried out at a first pre-selected pH to precipitate as insoluble metal complexes at least a portion of the Group VIB metal.

36. The method of claim 35, wherein H₂S is added to the first supernatant at a pressure from atmospheric to 100 psig and at a temperature ranging from 50 to 95°

C.

37. The method of claim 35, wherein sulfamic aid having a concentration of 20 wt % to 30 wt % is added to the coal liquefaction residue to dissolve at least 60% of the alkaline earth metal complexes together w/Fe &

Al.

38. The method of claim 37, wherein sulfamic acid having a concentration of 20 wt % to 30 wt % is added to the coal liquefaction residue to achieve a slurry pulp density of between 10 &

25-wt % solids.

39. The method of claim 38, wherein the dissolved alkaline earth metal complexes are separated and removed from the slurry containing the spent catalyst, ash and insoluble organic matter by at least a separation means selected from settling, filtration, decantation, centrifugation and combinations thereof to form a third supernatant containing dissolved alkaline earth metal complexes.