PROCESS FOR THE SELECTIVE REMOVAL OF COPPER COMPOUNDS AND OTHER IMPURITIES WITH RESPECT TO MOLYBDENUM AND RHENIUM, FROM MOLYBDENITE CONCENTRATES

• US 20200131047A1
• Filed: 07/01/2019
• Published: 04/30/2020
• Est. Priority Date: 10/30/2018
• Status: Active Grant

• Current Assignee: Molibdenos y Metales S.A.
• Original Assignee: Molibdenos y Metales S.A.
• Inventors: GUZMAN MANZO, Manuel Enrique, GRAELL MOORE, John Patrick
• Granted Patent: US 11,377,365 B2
• Time in Patent Office: Days
• CPC Class Codes: C01G 3/10 Sulfates
• CPC Class Codes: C01G 39/02 Oxides; Hydroxides
• CPC Class Codes: C01G 49/02 Oxides; Hydroxides C01G49/0018 takes precedence
• CPC Class Codes: C01G 49/14 Sulfates C01G49/0018 takes precedence
• CPC Class Codes: C01P 2006/80 Compositional purity
• CPC Class Codes: C22B 15/0071 containing sulfur
• CPC Class Codes: C22B 34/34 Obtaining molybdenum treatment or purification of solutions by adsorption on solids C22B3/24, by liquid-liquid extraction C22B3/26, by ion-exchange extraction C22B3/42; preparation of molybdenum involving liquid-liquid extraction, adsorption or ion-exchange C01G39/003
• CPC Class Codes: C22B 61/00 Obtaining metals not elsewhere provided for in this subclass iron C21
• CPC Class Codes: Y02P 10/20 Recycling

Abstract

Disclosed is a process for the selective removal of copper compounds, and other impurities with respect to molybdenum and rhenium, from concentrates of molybdenite (MoS₂) with a copper content that is higher than 0.5% in dry weight.

Claims

1. A process for the selective removal of copper compounds and other impurities with respect to molybdenum and rhenium from molybdenite concentrates (MoS₂) with a copper content of more than 0.5% in dry weight, comprising the following stages:

mixing a concentrate of impure MoS₂ (1) with process water and/or a leaching solution that is diluted with sulfuric acid (2), with a concentration of sulfuric acid is in the range of 0 to 20 g/l, in a repulping stage (3), to obtain a first pulp (4) with a solid content in the pulp of 50 to 20% in weight, maintaining equivalently a ratio of liquid to solid in the range of 1/1 to 4/1, volume/weight;

leaching the first pulp (4) inside a pressure reactor, in a pressurized leaching stage (6) at an oxidizing atmosphere, with an oxygen-bearing gas (5), at a leaching temperature between 110°

C.-180°

C. with a partial pressure for the oxidizing gas inside the reactor between 20-150 psig (0.1-1.0 MPa) to obtain a second pulp (7) containing the clean molybdenite concentrate and a solution or mother liquor containing the dissolved impurities, including the sulfuric acid that was generated in situ by the selective oxidation of the sulfur contained in the sulfides that initially formed the impurities in the dirty molybdenite concentrate;

carrying the second pulp (7) to a cooling tank (8), to get a third pulp (7a) with a temperature of at most 60°

C.;

carrying the third pulp (7a) to a solid/liquid separation stage (9) to obtain a clean molybdenite concentrate (10) with a percentage of copper of less than 0.5% in weight and a liquor (11) containing the copper and impurities in solution produced by the chemical reactions of the leaching stage (6).

2. The process, according to claim 1, wherein optionally the clean concentrate (10) can be carried to the following stages, comprising:

(e) carrying the clean molybdenite concentrate (10) to a washing stage (12), with washing water (13), to drag out the mother liquor that is impregnated in the clean molybdenite concentrate (10);

(f) carrying the washed clean molybdenite concentrate (14) to be drying, packing and storage;

or

(g) carrying the washed wet or dry clean molybdenite concentrate (14) to roasting to obtain technical grade molybdenum trioxide.

3. The process, according to claim 2, wherein the technical grade molybdenum trioxide obtained in stage (g) is used in the manufacture of other molybdenum products, such as ferromolybdenum, or is used as a precursor for the manufacture of pure molybdates from molybdenum, such as ammonium dimolybdate (ADM), ammonium heptamolybdate (AHM) and other molybdates.

4. The process, according to claim 1, wherein the liquor (11) obtained in stage (d) of the solid/liquid separation (9) may contain molybdenum and rhenium in solution, in which case the liquor rich in copper and impurity (11) is carried to a solvent extraction stage for the molybdenum and the rhenium.

5. The process, according to claim 1, wherein the liquor rich in copper and impurity (11) is, as an option, treated by consecutive stages of solvent extraction and electrodeposition, or cementation, for obtaining the copper.

6. The process, according to claim 1, wherein the liquor rich in copper and impurity (11) is, as an option, recirculated to the pressurized leaching stage (6).

7. The process, according to claim 1, wherein the leaching solution diluted with sulfuric acid (2) has a concentration of dilute sulfuric acid in the range of 0 to 20 g/l.

8. The process, according to claim 1, wherein the copper impurities present in the solid material (1) correspond to primary sulfides and secondary sulfides.

9. The process, according to claim 8, wherein the primary sulfides correspond to chalcopyrite (CuFeS₂) and the secondary sulfides correspond to chalcocite (Cu₂S) and covellite (CuS).

10. The process, according to claim 1, wherein the oxygen-bearing gas (5) is selected from:

pure oxygen, oxygen-enriched air or air.

11. The process, according to claim 1, wherein the pressure reactor is a horizontal or vertical autoclave, with one or more paddles, with one or more compartments separated by baffles, with submerged gas injection or injection on top or both.

12. The process, according to claim 1, wherein the residence time of the pulp inside the leaching reactor is between 15 and 240 minutes.

13. The process, according to claim 1, wherein the second pulp (7) resulting from the leaching stage (6) has a pH between 0 and 2 and a potential for oxidation/reduction between 0.2 and 0.5 volts vs Ag/AgCl.

14. The process, according to claim 1, wherein in stage (d), the solid/liquid separation stage (9) is carried out by:

filtration, sedimentation, clarification, thickening, centrifugation, dewatering and decantation.

15. The process, according to claim 14, wherein the solid/liquid separation stage (9) can be carried out by filtration in a plate or diaphragm filter, with a washing liquid-solid ratio between 0.2 and 1.0 volume/weight.