Activation system and method for enhancing metal recovery during atmospheric leaching of metal sulfides

Patent metadata

Field	Value
Publication number	US-11898221-B2
Application number	US-202016992644-A
Country	US
Kind code	B2
Filing date	Aug 13, 2020
Priority date	May 17, 2017
Publication date	Feb 13, 2024
Grant date	Feb 13, 2024

Abstract

A method of improving metal leach kinetics and recovery during atmospheric or substantially atmospheric leaching of a metal sulfide is disclosed. In some embodiments, the method may comprise the step of processing a metal sulfide concentrate in a reductive activation circuit 220 that operates at a first redox potential, to produce a reductively-activated metal sulfide concentrate. The method may further comprise the step of subsequently processing the activated metal sulfide concentrate in an oxidative leach circuit 240 to extract metal values. In some disclosed embodiments, reductive activation steps and/or oxidative dissolution steps may employ mechano-chemical and/or physico-chemical processing of particles or agglomerates thereof. Reductive activation may be made prior to heap leaching or bio-leaching operations to improve metal extraction. Systems for practicing the aforementioned methods are also disclosed.

First claim

What is claimed is:

1. A method of leaching a metal sulfide comprising:
providing a metal sulfide leach circuit 200 having therein, a reductive activation circuit 220 and an oxidative leach circuit 240 ; the reductive activation circuit 220 preceding the oxidative leach circuit 240 and being configured for performing metathesis reactions which are capable of producing an iron-depleted metastable phase on metal sulfide leach particles, wherein the reductive activation circuit 220 is configured such that the metathesis reactions produce the iron-depleted metastable phase at outer surface portions of the metal sulfide leach particles; the metal sulfide leach circuit 200 further being configured for controlling the metathesis reactions to limit the production of the iron-depleted metastable phase on the metal sulfide leach particles to between about 0.01% and about 10% by weight or volume of the metal sulfide leach particles;
maintaining the reductive activation circuit 220 at a pH between 2 and 6;
maintaining the oxidative leach circuit 240 at a pH below 1.8;
providing the metal sulfide leach particles to the reductive activation circuit 220 ;
producing an iron-depleted metastable phase on outer surface portions of the metal sulfide leach particles in the reductive activation circuit 220 ;
controlling metathesis reactions in the reductive activation circuit 220 to limit the production of the iron-depleted metastable phase on the metal sulfide leach particles to between about 0.01% and about 10% by weight or volume of the metal sulfide leach particles;
conveying the metal sulfide leach particles comprising the iron-depleted metastable phase to the oxidative leach circuit 240 ; and
leaching the metal sulfide leach particles comprising the iron-depleted metastable phase in the oxidative leach circuit 240 .

2. The method according to claim 1 , further comprising the step of producing the iron-depleted metastable phase at inner portions of the metal sulfide leach particles which are below outer surface portions of the metal sulfide leach particles in the reductive activation circuit 220 .

3. The method according to claim 1 , further comprising the step of producing point defects within a portion of each of the metal sulfide leach particles in the reductive activation circuit 220 .

4. The method according to claim 1 , further comprising the step of producing point defects substantially entirely throughout the metal sulfide leach particles in the reductive activation circuit 220 .

5. The method according to claim 1 , wherein a portion of the iron-depleted metastable phase comprises an intermediate phase between chalcopyrite and covellite.

6. The method according to claim 1 , wherein the reductive activation circuit 220 comprises at least one stirred-tank reactor 202 and the step of producing an iron-depleted metastable phase on outer surface portions of the metal sulfide leach particles in the reductive activation circuit 220 is performed in the at least one stirred-tank reactor 202 .

7. The method according to claim 1 , wherein the reductive activation circuit 220 comprises at least one shear-tank reactor 212 and the step of producing an iron-depleted metastable phase on outer surface portions of the metal sulfide leach particles in the reductive activation circuit 220 is performed in the at least one shear-tank reactor 212 .

8. The method according to claim 1 , wherein at least one stirred-tank reactor 202 and at least one shear-tank reactor 212 are configured in series within the reductive activation circuit 220 and the step of producing an iron-depleted metastable phase on outer surface portions of the metal sulfide leach particles in the reductive activation circuit 220 is performed in the at least one stirred-tank reactor 202 and the at least one shear-tank reactor 212 .

9. The method according to claim 1 , wherein at least one stirred-tank reactor 202 and at least one shear-tank reactor 212 are configured in parallel within the reductive activation circuit 220 and the step of producing an iron-depleted metastable phase on outer surface portions of the metal sulfide leach particles in the reductive activation circuit 220 is performed in the at least one stirred-tank reactor 202 and the at least one shear-tank reactor 212 .

10. The method according to claim 1 , wherein at least one shear-tank reactor 212 is disposed within at least one stirred-tank reactor 202 within the reductive activation circuit 220 and the step of producing an iron-depleted metastable phase on outer surface portions of the metal sulfide leach particles in the reductive activation circuit 220 is performed in the at least one stirred-tank reactor 202 and the at least one shear-tank reactor 212 .

11. The method according to claim 1 , wherein the oxidative leach circuit 240 comprises at least one stirred-tank reactor 202 and the step of leaching the metal sulfide leach particles comprising the iron-depleted metastable phase in the oxidative leach circuit 240 is performed in the at least one stirred-tank reactor 202 .

12. The method according to claim 1 , wherein the oxidative leach circuit 240 comprises at least one shear-tank reactor 212 and the step of leaching the metal sulfide leach particles comprising the iron-depleted metastable phase in the oxidative leach circuit 240 is performed in the at least one shear-tank reactor 212 .

13. The method according to claim 1 , wherein at least one stirred-tank reactor 202 and at least one shear-tank reactor 212 are configured in series within the oxidative leach circuit 240 and the step of leaching the metal sulfide leach particles comprising the iron-depleted metastable phase in the oxidative leach circuit 240 is performed in the at least one stirred-tank reactor 202 and at least one shear-tank reactor 212 .

14. The method according to claim 1 , wherein at least one stirred-tank reactor 202 and at least one shear-tank reactor 212 are configured in parallel within the oxidative leach circuit 240 and the step of leaching the metal sulfide leach particles comprising the iron-depleted metastable phase in the oxidative leach circuit 240 is performed in the at least one stirred-tank reactor 202 and at least one shear-tank reactor 212 .

15. The method according to claim 1 , wherein at least one shear-tank reactor 212 is disposed within the at least one stirred-tank reactor 202 within the oxidative leach circuit 240 and the step of leaching the metal sulfide leach particles comprising the iron-depleted metastable phase in the oxidative leach circuit 240 is performed in the at least one stirred-tank reactor 202 and at least one shear-tank reactor 212 .

16. The method according to claim 1 , wherein oxidative dissolution within the oxidative leach circuit 240 is substantially independent of the degree of completion of a conversion of the metal sulfide particles to the iron-depleted metastable phase and the step of leaching the metal sulfide leach particles comprising the iron-depleted metastable phase in the oxidative leach circuit 240 is performed independent of the degree of completion of a conversion of the metal sulfide particles to the iron-depleted metastable phase.

17. The method according to claim 1 , wherein the step of producing an iron-depleted metastable phase on outer surface portions of the metal sulfide leach particles in the reductive activation circuit 220 includes exposing the metal sulfide leach particles in the reductive activation circuit 220 for

Assignees

• Smidth As F L

Inventors

• Chaiko David J
• Baczek Frank
• Rocks Sara (Sally)
• Eyzaguirre Carlos

Classifications

• C22B3/04 Primary

  by leaching (C22B3/18 takes precedence) · CPC title

• C22B3/02

  Apparatus therefor · CPC title

• C22B15/0065

  Leaching or slurrying (with organic compounds C22B3/16) · CPC title

• C22B15/0095

  Process control or regulation methods · CPC title

• Y02P10/20

  Recycling · CPC title