PROCESS FOR RECOVERING GOLD AND SILVER FROM REFRACTORY ORES

• US 20090074607A1
• Filed: 09/11/2008
• Published: 03/19/2009
• Est. Priority Date: 09/18/2007
• Status: Active Grant

• Current Assignee: Barrick Gold Corporation
• Original Assignee: Barrick Gold Corporation
• Inventors: McMullen, Jacques, Gorain, Barun, Hillier, Daniel
• Granted Patent: US 7,922,788 B2
• Time in Patent Office: Days
• US Class Current: 420/501
• CPC Class Codes: B03D 1/02 Froth-flotation processes
• CPC Class Codes: B03D 1/1456 Feed mechanisms for the slurry
• CPC Class Codes: C22B 1/00 Preliminary treatment of ores or scrap
• CPC Class Codes: C22B 11/00 Obtaining noble metals
• CPC Class Codes: C22B 11/08 by cyaniding
• CPC Class Codes: Y02P 10/20 Recycling

Abstract

The present invention is directed to flotation of refractory gold sulfide ores in which the ore is ground, floated, the tailings reground, and refloated to produce gold-bearing concentrates.

Claims

1. A method, comprising:

(a) providing a refractory gold-bearing and sulfide-containing material;

(b) comminuting the material to form a feed material having a first size distribution;

(c) floating the feed material to form first and seconds fractions, the first and second fractions each comprising at least some of the gold and sulfides in the feed material;

(d) comminuting the second fraction to provide a comminuted second fraction, the comminuted second fraction having a second size distribution finer than the first size distribution; and

(e) further floating the comminuted second fraction to produce third and fourth fractions, the third fraction comprising at least most of the gold and sulfides in the second fraction.

2. The method of claim 1, wherein, in step (b), the material is wet milled to form the feed material and wherein step (b) comprises the sub-steps:

(B1) contacting a pH adjustor with the material to provide a pH ranging from about pH 3.5 to about pH 6.5;

(B2) contacting a sulfide activator with the material; and

(B3) contacting an electro potential adjustor with the material to provide an Eh level ranging from about +10 to about +200 mV.

3. The method of claim 2, wherein the sulfide activator and electro potential adjustor are the same reagent, wherein the reagent is a metal salt selected from the group consisting essentially of copper salts, lead salts, and mixtures thereof, wherein the first size distribution is a P₈₀ size ranging from about 100 to about 200 microns, and wherein the second size distribution is a P₈₀ size ranging from about 25 to about 100 microns.

4. The method of claim 2, wherein the material comprises carbon-containing materials and further comprising before step (c):

(f) contacting a carbon depressant with the feed material;

(g) after step (f), contacting an anionic collector with the feed material; and

(h) after step (g), contacting a frother with the feed material.

5. The method of claim 2, wherein step (d) comprises the sub-steps:

(D1) contacting a pH adjustor with the second fraction to provide a pH ranging from about pH 3.5 to about pH 6.5;

(D2) contacting a sulfide activator with the second fraction; and

(D3) contacting an electro potential adjustor with the second fraction to provide an Eh level ranging from about +10 to about +200 mV.

6. The method of claim 1, wherein the first and third fractions have a sulfide sulfur content of at least about 6.5 wt. %, wherein the feed material comprises silicates, wherein at least most of the silicates in the feed material are in the fourth fraction, wherein the feed material comprises preg robbing carbonaceous materials, and wherein the first and third fractions comprise no more than about 20% of the preg robbing carbonaceous materials.

7. The method of claim 1, wherein step (c) is flash flotation and further comprising:

(f) after step (c) and before step (d), size separating the second fraction to form oversized and undersized fractions and wherein the oversized fraction is recycled to step (b).

8. The method of claim 7, wherein step (e) is flash flotation and further comprising:

(f) after step (e), size separating the fourth fraction to form oversized and undersized fractions and wherein the oversized fraction is recycled to step (d).

17. The method of claim 6, wherein step (g) is flash flotation and further comprising:

after step (g), size separating the second tailings fraction to form oversized and undersized fractions and wherein the oversized fraction is recycled to step (e).

9. Gold recovered from the first and third fractions.

10. A method, comprising:

(a) providing a gold and/or silver-bearing and sulfide-containing material;

(b) comminuting the material to form a feed material having a first size distribution;

(c) contacting the feed material with a pH adjustor and at least one of a sulfide activator and an electro potential adjustor to provide a conditioned feed material;

(d) floating the conditioned feed material to form first concentrate and tailings fractions, the first concentrate and tailings fractions each comprising at least some of the valuable metal and sulfides in the conditioned feed material;

(e) comminuting the first tailings fraction to provide comminuted tailings, the comminuted tailings having a second size distribution finer than the first size distribution;

(f) contacting the comminuted tailings with at least one of a sulfide activator and electro potential adjustor to provide conditioned tailings;

(g) floating the conditioned tailings to produce second concentrate and tailings fractions, the second concentrate fraction comprising at least most of the gold and/or silver and sulfides in the conditioned tailings;

(h) thereafter recovering the gold and/or silver from the first and second concentrates.

11. The method of claim 10, wherein, in step (b), the material is wet milled to form the feed material, and wherein step (c) comprises the sub-steps:

(C1) contacting the pH adjustor with the material to provide a pH ranging from about pH 3.5 to about pH 6.5;

(C2) contacting the sulfide activator with the material; and

(C3) contacting the electro potential adjustor with the material to provide an Eh level ranging from about +10 to about +200 mV.

12. The method of claim 11, wherein the at least one of a sulfide activator and electro potential adjustor is a metal salt selected from the group consisting essentially of copper salts, lead salts, and mixtures thereof, wherein the first size distribution is a P₈₀ size ranging from about 100 to about 200 microns, and wherein the second size distribution is a P₈₀ size ranging from about 25 to about 100 microns.

13. The method of claim 11, wherein the material comprises preg robbing carbon-containing materials and wherein step (c) further comprises the sub-steps:

(C4) contacting a carbon depressant with the material;

(C5) after step (C4), contacting an anionic collector with the material; and

(C6) after step (C5), contacting a frother with the material.

14. The method of claim 11, wherein step (f) comprises the sub-steps:

(F1) contacting the pH adjustor with the first tailings fraction to provide a pH ranging from about pH 3.5 to about pH 6.5;

(F2) contacting the sulfide activator with the first tailings fraction; and

(F3) contacting the electro potential adjustor with the first tailings fraction to provide an Eh level ranging from about +10 to about +200 mV.

15. The method of claim 10, wherein the first and second concentrate fractions have a sulfide sulfur content of at least about 6.5 wt. %, wherein the feed material comprises silicates, wherein at least most of the silicates in the feed material are in the second tailings fraction, wherein the feed material comprises preg robbing carbonaceous materials, and wherein the first and second concentrates comprise no more than about 20% of the preg robbing carbonaceous materials.

16. The method of claim 10, wherein step (d) is flash flotation and further comprising:

after step (d) and before step (g), size separating the first tailings fraction to form oversized and undersized fractions and wherein the oversized fraction is recycled to step (b).

18. Gold and/or silver recovered by the process of claim 10.

19. A method, comprising:

(a) providing a refractory gold-bearing and sulfide-containing material;

(b) comminuting the material to form a feed material having a first size distribution;

(c) conditioning the feed material by;

(C1) contacting a pH adjustor with the material to provide a pH ranging from about pH 3.5 to about pH 6.5; and

(C2) contacting an electro potential adjustor with the material to provide an Eh level ranging from about +10 to about +200 mV;

(d) floating the conditioned feed material to form first concentrate and tailings fractions, the first concentrate and tailings fractions each comprising at least some of the gold and sulfides in the feed material;

(d) comminuting the first tailings fraction to provide comminuted tailings, the comminuted tailings having a second size distribution finer than the first size distribution;

(e) conditioning the comminuted tailings by;

(E1) contacting a pH adjustor with the comminuted tailings to provide a pH ranging from about pH 3.5 to about pH 6.5; and

(E2) contacting an electro potential adjustor with the comminuted tailings to provide an Eh level ranging from about +10 to about +200 mV; and

(f) further floating the conditioned comminuted tailings to produce second concentrate and tailings fractions, the second concentrate fraction comprising at least most of the gold and sulfides in the first tailings fraction.

20. The method of claim 19, further comprising:

(g) recovering the gold from the first and second concentrates.