Processing method

1 . A method of processing a pyrite-containing slurry that comprises:

(a) removing pyrite from the pyrite-containing slurry and forming (i) an inert stream and (ii) a pyrite-containing material, with the pyrite-containing slurry including tailings from a tailings dam or an ore processing plant;

(b) mixing together a metal sulfide-containing material and the pyrite-containing material; and

(c) leaching the metal sulfide-containing material and the pyrite-containing material with an acidic leach liquor and microbes and removing a metal from the metal sulfide-containing material and forming a pregnant leach liquor containing metal, with the pyrite in the pyrite-containing material generating acid and heat that facilitate leaching of the metal from the metal sulfide-containing material, and with the microbes oxidising ferrous iron to ferric iron, wherein the metal is copper, nickel, zinc, or cobalt.

2 . The method defined in claim 1 wherein the pyrite removal step (a) includes floating the pyrite-containing material in the pyrite-containing slurry and producing (i) the inert stream as one flotation output and (ii) the pyrite-containing material as another flotation output.

3 . The method defined in claim 2 wherein, before the flotation step, the pyrite removal step (a) includes a size separation step which separates larger particles in the pyrite-containing material from the remaining pyrite-containing slurry, with the remaining pyrite-containing slurry being transferred to the flotation step.

4 . The method defined in claim 3 wherein the pyrite removal step (a) includes reducing the size of the larger particles in the pyrite-containing material in a size reduction circuit to form reduced-sized particles and returning the reduced-sized particles to the size separation step.

5 . The method defined in claim 3 wherein the pyrite removal step (a) includes selecting the operating conditions so that pyrite particles in the pyrite-containing material in the remaining pyrite-containing slurry have a required particle size distribution for the downstream leach step (b).

6 . The method defined in claim 1 wherein pyrite particles in the pyrite-containing material have a particle size of P 80 of 1 mm or a value <1 mm.

7 . The method defined in claim 6 wherein the pyrite particles in the pyrite-containing material have a particle size of P 80 of 250 μm or a value <250 μm.

8 . The method defined in claim 1 wherein the pyrite removal step (a) includes thickening and/or filtering the pyrite-containing material and forming a pyrite-containing concentrate.

9 . The method defined in claim 1 includes using the inert stream as a source of water in processing plants for recovering metal from the metal sulfide-containing material.

10 . The method defined in claim 1 wherein the metal is copper and the metal sulfide-containing material is a copper sulfide mineral.

11 . The method defined in claim 10 wherein pyrite is 1-10 wt. % of the total mass of the copper sulfide-containing material and the pyrite-containing material.

12 . The method defined in claim 1 includes mixing together the metal sulfide-containing material and the pyrite-containing material before the leaching step (b).

13 . The method defined in claim 12 wherein the leaching step (b) includes:

i. agglomerating the pyrite-containing material and the metal sulfide-containing material, such as copper sulfide containing material, and forming agglomerates; and

ii. heap leaching the metal, such as copper, from a heap of the agglomerates and producing a pregnant leach liquor containing the metal, such as copper, in solution; and

iii. recovering the metal, such as copper, from the pregnant leach liquor.