Process for separating and recovering base metals from used hydroprocessing catalyst

• US 7,846,404 B2
• Filed: 12/19/2008
• Issued: 12/07/2010
• Est. Priority Date: 11/28/2007
• Status: Active Grant

• Current Assignee: Chevron USA Incorporated (Chevron Corp.)
• Original Assignee: Chevron USA Incorporated (Chevron Corp.)
• Inventors: Bhaduri, Rahul S., Berezowsky, Roman, Stiksma, John
• Primary Examiner(s): Mayes; Melvin C
• Assistant Examiner(s): STALDER, MELISSA A
• Application Number:
  US12/340,404
• Publication Number:
  US 20090133536A1
• Time in Patent Office: 718 Days
• Field of Search: 423/56, 423/55, 423/67, 423/68, 423/40
• US Class Current: 423/56
• CPC Class Codes: C22B 23/0461 by chemical methods
• CPC Class Codes: C22B 3/14 containing ammonia or ammonium salts
• CPC Class Codes: C22B 34/345 from spent catalysts
• CPC Class Codes: C22B 7/008 by an alkaline or ammoniacal leaching
• 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

A method is disclosed for separating and recovering base metals from a used hydroprocessing catalyst originating from Group VIB and Group VIII metals and containing at least a Group VB metal. In one embodiment, the used catalyst is contacted with an ammonia leaching solution to dissolve and separate the Group VIB and VIII metals from the Group VB metal complex and coke associated with the used catalyst. The resulting Group VIB and VIII metal containing solution is processed through at least two additional precipitation and liquid/solid separation steps to produce, in separate processing streams, a Group VIB metal product solution (such as ammonium molybdate) and a Group VIII metal product solution (such as nickel sulfate). Additionally, two separate filtrate streams are generated from liquid-solid separation steps, which filtrate streams are combined and subjected to hydrolysis and oxidation (oxydrolysis) to generate a purified ammonium sulfate solution for further processing, such as for fertilizer.

Claims

1. A method of recovering metals from a used catalyst comprising the steps of:

(a) leaching a Group VB metal, a Group VIB metal and a Group VIII metal from the used catalyst with an ammonia containing leach solution at a temperature and a pressure sufficient to form a pressure leach slurry comprising at least a Group VIB soluble metal complex and at least a Group VIII soluble metal complex and a first solid residue;

(b) separating and removing the first solid residue from the pressure leach slurry to form a first pressure leach solution comprising the Group VIB soluble metal complex and the Group VIII soluble metal complex;

(c) precipitating from the first pressure leach solution a second solid residue comprising at least a portion of the Group VIB soluble metal complex to form a first slurry comprising the second solid residue and at least a portion of the Group VIII soluble metal complex;

(d) separating from the first slurry the second solid residue and a primary filtrate substantially free of Group VB, Group VIB and the Group VIII metals;

(e) dissolving the second solid residue to form a group VIB metal precipitate and a group VIII metal containing solution;

(f) separating the group VIB metal precipitate from the Group VIII metal containing solution of step (e);

(g) dissolving said Group VIB metal precipitate in a dilute base at a sufficient temperature to form a Group VIB metal product.

2. The method of claim 1 wherein the step (f) further comprises:

(i) forming a secondary filtrate comprising substantially ammonium sulphate, the Group VIII soluble metal complex and trace amounts of Group VB and Group VIB metals;

(ii) processing the primary filtrate in a primary precipitation method to form a primary solid residue and a primary liquid fraction and separately processing the secondary filtrate in a secondary precipitation method to form a secondary solid residue and a secondary liquid fraction;

(iii) separating the primary solid residue from the primary liquid fraction and combining the primary solid residue with the used catalyst of step (a) of claim 1;

(iv) separating the secondary solid residue from the secondary liquid fraction and dissolving the secondary solid residue to form a Group VIII product solution.

3. The method of claim 2 further comprising combining the primary liquid fraction and the secondary liquid fraction to form a combined solution substantially free Group VB, Group VIB and Group VIII metals.

4. The method of claim 3 further comprising subjecting the combined solution to sulfamate hydrolysis and sulfide oxidation at a temperature between 220°

C. and 240°

C., a pressure ranging from 2,000-kPa to 4,000-kPa and a retention time of between 0.5-hour and 1.5-hour to form a purified solution.

5. The method of claim 4 wherein the purified solution is ammonium sulfate.

6. The method of claim 1 wherein the precipitation step (c) is carried out at a pH not more than 3.0, at a temperature between about 75°

C. and 85°

C. for at least two hours.

7. The method of claim 1 wherein the first solid residue comprises at least a Group VB metal, a Group VB metal complex and Coke.

8. The method of claim 7, wherein the Group VB metal comprises vanadium and the Group VB metal complex comprises ammonium metavanadate.

9. The method of claim 1 wherein the separation steps (b), (d) and (f) each comprise at least a separation means selected from settling, filtration, decantation, centrifugation and combinations thereof.

10. The method of claim 1, wherein the primary filtrate comprises substantially ammonium sulfate and about 0.1 to 3% of the Group VIB metal in the used catalyst for metal recovery, about 1 to 20% of the Group VB metal in the used catalyst for metal recovery, and about 1 to 35% of the Group VIII metal in the used catalyst for metal recovery.

11. The method of claim 2 wherein the primary precipitation method comprises sulfidation with a sulfur containing compound and a phosphate at a temperature and pressure and for a time sufficient to remove at least 90% of the Group VB metals and at least 95% of the Group VIB and Group VIII metals.

12. The method of claim 11 wherein the phosphate is a salt of di-ammonium hydrogen phosphate which is added to the primary filtrate immediately prior to sulfidation.

13. The method of claim 11 wherein the primary filtrate comprises less than 500 ppm nickel and less than 1000 ppm of molybdenum and vanadium combined with an ammonium sulfate content of at least 400 gpL, the pH is initially adjusted to approximately 8 with ammonia and the primary precipitation method comprises sulfidation carried out at 100 kPa overpressure with hydrogen sulfide gas at a temperature between about 90°

C. and 110°

C. for 80 to 100 minutes and the pH is adjusted at least 2 times from basic to acidic and from acidic to basic.

14. The method of claim 2 wherein the secondary precipitation method comprises sulfidation with a sulfur containing compound at a temperature and pressure and for a time sufficient to remove at least 90% of the Group VB metals and at least 95% of the Group VIB and Group VIII metals.

15. The method of claim 14 wherein the sulfidation is carried out with hydrogen sulfide gas at an overpressure of 100 kPa, at a temperature between 90°

C. and 120°

C. at a pH between 8 and 9 and between 50 and 80 minutes.

16. The method of claim 2, wherein the separation steps (iii) and (iv) are separation means selected from settling, filtration, decantation, centrifugation and combinations thereof.

17. The method of claim 3 wherein the combined solution comprises less than 100 ppm of the group VIB metal, less than 20 ppm of the Group VIII metal, and less than 100 ppm of the Group VB metal.

18. The method of claim 1, wherein at least 90% of the Group VIB metal precipitates from the pressure leach solution as a metal complex.

19. The method of claim 1, wherein the Group VIB metal is molybdenum and wherein the first pre-selected pH is in the range of 2.5 to 3.3 to precipitate greater than 90% of the molybdenum as an octamolybdate complex.

20. The method of claim 19, wherein the pressure leach solution is adjusted to the first pre-selected pH by adding to said solution at least one of a mineral acid or a sulfur compound having a sulfhydryl group or an ionized sulfhydryl group, or mixtures thereof.

21. The method of claim 20, wherein the pH of the PLS is adjusted to a pH of 3.5 or less with an acid selected from the group of sulfuric acid, hydrochloric acid, phosphoric acid and nitric acid.

22. The method of claim 20, wherein the PLS is adjusted to a pH of 3 or less with the addition of a sulfuric acid to precipitate at least 95% of the molybdenum as an octamolybdate complex.

23. The method of claim 20, wherein the pH of the pressure leach solution is adjusted to a pH of 3 or less with at least one of a water soluble sulfide, a water soluble polysulfide, or mixtures thereof.

24. The method of claim 2, wherein the Group VIB metal in the used catalyst is molybdenum, the Group VIII metal in the used catalyst is nickel, the Group VB metal in the used catalyst is vanadium, the pressure leach solution is adjusted to a pH of 3.5 or less with the addition of a sulfuric acid to precipitate and form the second solid residue comprising at least 95% of the molybdenum as an octamolybdate complex and at least 75% of the nickel as a nickel ammonium sulfate compound, dissolving the second solid residue in an acidic water having a pH of 2.5 or less at a temperature ranging between 75°

C. and 85°

C. to form an octamolybdate precipitate and a solution of a double salt of nickel and dissolving the octamolybdate precipitate in dilute ammonia at a temperature ranging from 50°

C. to 75°

C. to form an ammonium molybdate product.

25. The method of claim 24 further comprising:

separating the octamolybdate precipitate from the double salt of nickel solution to form the secondary filtrate comprising at least 80% of the nickel present in the used catalyst, from 0.1 to 3% of the molybdenum present in the used catalyst and from 1 to 20% of the vanadium present in the used catalyst;

adding H₂S to the secondary filtrate at a gas overpressure ranging from 100-kPa to 500-kPa and at a temperature ranging from 50-110°

C. to precipitate the secondary solid residue comprising Mo, Ni, and V sulfides and oxy-hydroxides, obtain the secondary liquid fraction comprising 100 to 1000 gpL ammonium sulfate, less than 100 ppm molybdenum, less than 20 ppm nickel, and less than 100 ppm vanadium;

separating the secondary solid residue and the secondary liquid fraction;

dissolving the secondary solid residue at a pH of five or less in the presence of oxygen at a temperature between 150°

C. and 170°

C., a total pressure ranging from 150 psig to 170 psig for a time between 30 minutes and 1.5 hours to obtain a nickel sulfate product solution having a pH of less than 1;

combining the secondary liquid fraction with the primary liquid fraction to form a combined solution;

subjecting the combined solution to sulfamate hydrolysis and soluble sulfide species oxidation in the presence of steam and air at a temperature ranging between 220°

C. and 240°

C. to form a purified solution comprising of ammonium sulfate.

26. The method of claim 13, wherein the primary filtrate comprises less than 400 ppm nickel and less than 1000 ppm of molybdenum and vanadium combined and an ammonium sulfate content of at least 400 gpL, the pH is initially adjusted to approximately 8 with ammonia;

the primary precipitation method comprises sulfidation carried out between 90 kPa and 110 kPa overpressure with hydrogen sulfide gas at a temperature between about 90°

C. and 110°

C. for 60 to 80 minutes and the pH is adjusted at least 2 times from basic to acidic and from acidic to basic to form a primary liquid fraction and a primary solid residue;

separating the primary liquid fraction and the primary solid residue;

transferring the primary solid residue to step (a) of claim 1;

combining the primary liquid fraction with the secondary liquid fraction to form the combined solution;

subjecting the combined solution to sulfamate hydrolysis and sulfide oxidation in the presence of steam and air at a temperature ranging between 220°

C. and 240°

C. to form a purified solution comprising ammonium sulfate.

27. The method of claim 2, wherein at least one of a water soluble sulfide, a water soluble polysulfide, or mixtures thereof is added to the secondary filtrate for a pH level of between 6 and 9 to obtain Mo, Ni, and V sulfide and oxy-hydroxide precipitates from the ammonium sulfate solution.

28. The method of claim 13, wherein H₂S is added to the primary filtrate at a gas overpressure from 100-kPa to 500 kPa and at a temperature ranging from about 90°

C. to about 110°

C.

30. The method of claim 29, further comprising the steps of:

(i) forming a secondary filtrate comprising substantially ammonium sulphate, the Group VIII soluble metal complex and trace amounts of Group VB and Group VIB metals;

(ii) processing the primary filtrate in a primary precipitation method to form a primary solid residue and a primary liquid fraction and separately processing the secondary filtrate in a secondary precipitation method to form a secondary solid residue and a secondary liquid fraction;

(iii) separating the primary solid residue from the primary liquid fraction and combining the primary solid residue with the used catalyst of step (a) of claim 1;

(iv) separating the secondary solid residue from the secondary liquid fraction and dissolving the secondary solid residue to form a Group VIII product solution.

34. A method of recovering metals including vanadium from a used catalyst having a general formula (M^t)_a(X^u)_b(S^v)_d(S^v)_d(C^w)_e(H^x)_f(O^y)_g(N^z)_h containing at least a Group VB metal, wherein M is at least one group VIB metal, X is at least one of a non-noble Group VIII metal, a Group VIIIB metal, a Group VIB metal, a Group IVB metal, and a Group IIB metal, 0=<

b/a=<

5, (a+0.5b)<

=d<

=(5a+2b), 0<

=e<

=11(a+b), 0<

=f<

=7(a+b), 0<

=g<

=5(a+b), 0<

=h<

=0.5(a+b);

t, u, v, w, x, y, z, each representing total charge for each of;

M, X, S, C, H, O and N, respectively;

ta+ub+vd+we+xf+yg+zh=0;

(a) leaching a Group VB metal, a Group VIB metal and a Group VIII metal from the used catalyst with an ammonia containing leach solution at a first selected pH and at a temperature and a pressure sufficient to form a pressure leach slurry comprising at least a Group VIB soluble metal complex and at least a Group VIII soluble metal complex and a first solid residue;

(b) separating and removing the first solid residue from the pressure leach slurry to form a first pressure leach solution comprising the Group VIB soluble metal complex and the Group VIII soluble metal complex;

(c) precipitating from the first pressure leach solution a second solid residue comprising at least a portion of the Group VIB soluble metal complex to form a first slurry comprising at least a portion of the Group VIII soluble metal complex;

(d) separating from the first slurry the second solid residue and a primary filtrate substantially free of Group VB, Group VIB and the Group VIII metals;

(e) dissolving the second solid residue to form a group VIB metal precipitate and a group VIII metal containing solution;

(f) separating the group VIB metal precipitate from the Group VIII metal containing solution of step (e) and dissolving said Group VIB metal precipitate in a dilute base at a sufficient temperature to form a Group VIB metal product;

(g) forming a secondary filtrate comprising substantially ammonium sulphate, the Group VIII soluble metal complex and trace amounts of Group VB and Group VIB metals;

(h) processing the primary filtrate in a primary precipitation method to form a primary solid residue and a primary liquid fraction and separately processing the secondary filtrate in a secondary precipitation method to form a secondary solid residue and a secondary liquid fraction;

(i) separating the primary solid residue from the primary liquid fraction and combining the primary solid residue with the used catalyst of step (a) of claim 1;

(j) separating the secondary solid residue from the secondary liquid fraction and dissolving the secondary solid residue to form a Group VIII product solution.

29. A method of recovering metals from a used catalyst originating from a hydroprocessing catalyst having a general formula (X)_a(M)_b[(CH₃CH₂)_cN(CH₃)₃]_dO_z and containing at least a group VB metal, wherein X is a Group VIII non-noble metal, M is a group VIB metal selected from Mo and W and combinations thereof, c is an integer from 10 to 40, the molar ratio of a:

b is from 0.5/1 to 3/1, the method comprising the steps of;

(a) leaching a Group VB metal, a Group VIB metal and a Group VIII metal from the used catalyst with an ammonia containing leach solution at a first selected pH and at a temperature and a pressure sufficient to form a pressure leach slurry comprising at least a Group VIB soluble metal complex and at least a Group VIII soluble metal complex and a first solid residue;

(b) separating and removing the first solid residue from the pressure leach slurry to form a first pressure leach solution comprising the Group VIB soluble metal complex and the Group VIII soluble metal complex;

(c) precipitating from the first pressure leach solution a second solid residue comprising at least a portion of the Group VIB soluble metal complex to form a first slurry comprising at least a portion of the Group VIII soluble metal complex;

(d) separating from the first slurry the second solid residue and a primary filtrate substantially free of Group VB, Group VIB and the Group VIII metals;

(e) dissolving the second solid residue to form a group VIB metal precipitate and a group VIII metal containing solution;

(f) separating the group VIB metal precipitate from the Group VIII metal containing solution of step (e) and

(g) dissolving said Group VIB metal precipitate in a dilute base at a sufficient temperature to form a Group VIB metal product.

31. The method of claim 29, wherein the Group VIB metal is molybdenum and wherein the first pre-selected pH is in the range of 2.5 to 3.3 to precipitate greater than 90% of the molybdenum.

32. The method of claim 29, wherein the used catalyst originating from a hydroprocessing catalyst having a median particle size of 0.01 to 200 microns.

33. The method of claim 29, wherein the used catalyst has a pore volume of 0.05-5 ml/g as determined by nitrogen adsorption.