Method of processing a pyrite-containing slurry
A method of processing a pyrite-containing slurry including removing pyrite from the pyrite-containing slurry and forming (i) an inert stream and (ii) a pyrite-containing material. Using the pyrite-containing material in a downstream leach step in which pyrite in the pyrite-containing material generates acid and heat that facilitates leaching a metal, such as copper or nickel or zinc or cobalt, from a metal-containing material.
1. A method of removing copper from a low-grade copper-containing material having copper sulfide minerals comprising
(a) obtaining a pyrite-containing slurry from a tailings dam or directly from a tailings stream of an ore processing plant;
(b) removing pyrite from the pyrite-containing slurry by floating pyrite-containing particles and forming
(i) an inert stream and
(ii) a pyrite-containing material including pyrite-containing particles;
(c) mixing a low-grade copper-containing material having copper sulfide minerals with the pyrite-containing material and forming agglomerates, and
(d) leaching copper from the copper-containing material in the agglomerates from step (c) with a leach liquor and microbes,
wherein the pyrite in the pyrite-containing material generates acid and heat that facilitates leaching copper from the copper-containing material, and
wherein the microbes oxidize ferrous iron to ferric iron.
2. The method defined in claim 1 wherein the pyrite removing step (b) includes a size separation step which separates larger particles from the pyrite-containing slurry before removing pyrite from the pyrite-containing slurry.
3. The method defined in claim 2 wherein the pyrite removing step (b) includes reducing the size of the larger particles in a size reduction circuit and returning the reduced-sized particles to the size separation step.
4. The method defined in claim 3 wherein the pyrite removing step (b) includes selecting operating conditions so that pyrite particles in the pyrite-containing material have a required particle size distribution for the leaching step (d).
5. The method defined in claim 4 wherein the pyrite particles in the pyrite-containing material have a particle size of P 80 of ≤1 mm.
6. The method defined in claim 4 wherein the pyrite particles in the pyrite-containing material have a particle size of P 80 of ≤250 μm.
7. The method defined in claim 1 wherein the pyrite removing step (a) includes thickening and/or filtering the pyrite-containing material and de-watering the pyrite-containing slurry and forming a pyrite-containing concentrate.
8. The method defined in claim 1 includes using the inert stream as a source of water in processing plants for recovering metal from the copper-containing material.
9. The method defined in claim 1 wherein pyrite is 1-10 wt. % of the total mass of the copper-containing material and the pyrite-containing material.
10. The method defined in claim 1 wherein the leaching in step (d) includes:
i. heap leaching copper from a heap of the agglomerates and producing a pregnant leach liquor contain copper in solution; and
ii. recovering copper from the pregnant leach liquor.
11. The method defined in claim 10 wherein the low-grade copper containing material includes rock.
12. The method defined in claim 1 wherein the microbes are bacteria and archaea.
13. The method of claim 2 wherein the inert stream is a source of water for recovering metal from the copper-containing material.
14. A method of removing copper from a low-grade copper-containing material having copper sulfide minerals comprising:
(a) obtaining a pyrite-containing slurry from a tailings dam or directly from a tailings stream of an ore processing plant;
(b) removing pyrite from the pyrite-containing slurry by floating pyrite-containing particles and forming (i) an inert stream and (ii) a pyrite-containing material that includes pyrite-containing particles, including selecting operating conditions so that pyrite particles have a required particle size distribution for leaching step (d);
(c) mixing a low-grade copper-containing material having copper sulfide minerals with the pyrite-containing material and forming agglomerates, and
(d) leaching copper from the copper-containing material in the agglomerates from step (c) with a leach liquor and microbes,
wherein the pyrite in the pyrite-containing material generates acid and heat that facilitates leaching copper from the copper-containing material, and
wherein the microbes oxidize ferrous iron to ferric iron.
15. A method of removing copper from a low-grade copper-containing material having copper sulfide minerals comprising:
(a) obtaining a pyrite-containing slurry from a tailings dam or directly from a tailings stream of an ore processing plant;
(b) removing pyrite from the pyrite-containing slurry by the steps of separating larger particles from the remaining pyrite-containing slurry, reducing the size of the larger particles in a size reduction circuit and returning the reduced-sized particles to the size separation step, and floating pyrite-containing particles in the remaining slurry and forming (i) an inert stream and (ii) a pyrite-containing material, including selecting operating conditions so that pyrite particles have a required particle size distribution for leaching step (d);
(c) mixing a low-grade copper-containing material having copper sulfide minerals and the pyrite-containing material and forming agglomerates, and
(d) leaching copper from the copper-containing material in the agglomerates from step (c) with a leach liquor and microbes,
wherein the pyrite in the pyrite-containing material generates acid and heat that facilitates leaching copper from the copper-containing material, and
wherein the microbes oxidize ferrous iron to ferric iron.