Recovering Metal from Metal-Bearing Material

Abstract

A method of recovering a metal, such as copper or nickel or zinc or cobalt, from a metal sulfide-containing material in a mined material that is “non-economic” to recover metals from using conventional recovery options before the invention was made is disclosed. The method includes mixing (i) the metal sulfide-containing material and (ii) pyrite and forming agglomerates, leaching agglomerates with a leach liquor and microbes and removing a metal from the metal sulfide-containing material and forming a pregnant leach liquor containing metal, and recovering the metal from the pregnant leach liquor. A heap leaching operation for a metal sulfide-containing material is also disclosed. A flotation circuit for an ore processing plant for a metal sulfide-containing material is also disclosed.

1 . A method of recovering a metal, such as copper or nickel or zinc or cobalt, from a metal sulfide-containing material in a mined material, such as a metal sulfide-containing material that is “non-economic” to recover metals from using conventional recovery options before the invention was made, that includes the steps of:
 (a) mixing (i) the metal sulfide-containing material and (ii) pyrite and forming agglomerates; 
 (b) leaching agglomerates from step (a) with a leach liquor and microbes and removing a metal from the metal sulfide-containing material and forming a pregnant leach liquor containing metal, with pyrite generating acid and heat facilitating leaching metal from the metal sulfide-containing material, and with the microbes oxidising ferrous iron to ferric iron; and 
 (c) recovering the metal from the pregnant leach liquor. 
 
     
     
         2 . The method defined in  claim 1  wherein the metal sulfide-containing material is in the form of as-mined material or stockpiled material that has been processed to be suitable for the agglomeration step (b). 
     
     
         3 . The method defined in  claim 2  includes comminuting as-mined or stockpiled material and producing a suitable particle size distribution for the agglomeration step (b). 
     
     
         4 . The method defined in  claim 3  includes crushing as-mined or stockpiled material in one or more than one comminution circuit that reduces the size of the material. 
     
     
         5 . The method defined in  claim 4  includes crushing as-mined or stockpiled material successively in primary, secondary and tertiary comminution circuits. 
     
     
         6 . The method defined in  claim 1  wherein the pyrite is in a pyrite-containing slurry, such as mine tailings. 
     
     
         7 . The method defined in  claim 1  wherein the pyrite is derived from a pyrite-containing slurry, such as mine tailings. 
     
     
         8 . The method defined in  claim 7  includes removing pyrite from the pyrite-containing slurry and producing pyrite in a concentrate form. 
     
     
         9 . The method defined in  claim 7  wherein the pyrite removal step (a) includes removing pyrite from the pyrite-containing slurry and forming (i) a pyrite-containing material and (ii) an inert stream. 
     
     
         10 . The method defined in  claim 1  wherein the mixing step is carried out before the agglomerating step. 
     
     
         11 . The method defined in  claim 1  wherein the mixing and the agglomerating steps are carried out simultaneously. 
     
     
         12 . The method defined in  claim 1  wherein the leaching step is a heap leaching step. 
     
     
         13 . A heap leaching method for a metal sulfide-containing material that contains a metal, such as copper or nickel or zinc or cobalt, in a mined material that comprises:
 (a) leaching a heap of agglomerates of the metal sulfide-containing material and pyrite with a leach liquor containing microbes and producing a pregnant leach liquor containing the metal in solution, with the pyrite generating acid and heat that facilitates leaching metal from the metal sulfide-containing material, with the pyrite being in or derived from a slurry containing pyrite, and with the microbes oxidising ferrous iron to ferric iron; and   (b) collecting the pregnant leach liquor from the heap.   
     
     
         14 . A heap leaching operation for leaching a metal, such as copper or nickel or zinc or cobalt, from a metal sulfide-containing material in a mined material, the heap leaching operation comprising:
 (a) a heap of agglomerates of the metal sulfide-containing material and pyrite; and   (b) a system that (i) supplies a leach liquor and microbes to the heap so that the leach liquor flows downwardly though the heap and leaches the metal from the metal sulfide-containing material and (ii) collects a pregnant leach liquor containing the metal in solution from the heap, with the pyrite generating acid and heat in the heap that facilitates leaching the metal from the metal sulfide-containing material, with pyrite being in or derived from a slurry containing pyrite, and with the microbes oxidising ferrous iron to ferric iron.   
     
     
         15 . The heap leaching operation defined in  claim 14  wherein pyrite is 1-10 wt. % of the total mass of the agglomerates. 
     
     
         16 . A flotation circuit for an ore processing plant for a metal sulfide-containing material, the flotation circuit including:
 (a) a mill feed flotation circuit for producing a tailings stream and a concentrate stream from a mill feed, with the tailings stream comprising a metal sulfide-containing material; and   (b) a pyrite flotation circuit for producing a pyrite concentrate stream, i.e. a pyrite-containing slurry, and a tailings stream.   
     
     
         17 . The flotation circuit defined in  claim 16  wherein the pyrite concentrate stream is a source of pyrite for the method of recovering a metal, such as copper, nickel or zinc or cobalt, from a metal sulfide-containing material that includes the steps of:
 (a) mixing (i) the metal sulfide-containing material and (ii) pyrite and forming agglomerates; 
 (b) leaching agglomerates from step (a) with a leach liquor and microbes and removing a metal from the metal sulfide-containing material and forming a pregnant leach liquor containing metal, with pyrite generating acid and heat facilitating leaching metal from the metal sulfide-containing material, and with the microbes oxidising ferrous iron to ferric iron; and 
 (c) recovering the metal from the pregnant leach liquor. 
 
     
     
         18 . The flotation circuit defined in  claim 16  wherein the pyrite flotation circuit is configured to process the pyrite concentrate stream, i.e. the pyrite-containing slurry, in accordance with the pyrite removal step including removing pyrite from a pyrite-containing slurry and forming a pyrite-containing material and an inert stream and produce (i) the tailings stream as the inert stream and (ii) the pyrite concentrate stream as the pyrite-containing material stream. 
     
     
         19 . The flotation circuit defined in  claim 16  wherein the mill feed flotation circuit includes a rougher/scavenger cell and a bulk cleaner cell, with the rougher/scavenger and the bulk cleaner cells being configured so that: (i) the rougher/scavenger cell processes the mill feed and produces a first tailings stream and a concentrate stream, and (ii) the bulk cleaner cell processes the concentrate stream and produces a second tailings stream and another concentrate stream and transfers the other concentrate stream for further processing, such as metal recovery, and the second tailings stream to the pyrite flotation circuit for processing in that circuit. 
     
     
         20 . The flotation circuit defined in  claim 16  wherein the metal sulfide-containing material is a copper sulfide-containing material, such as a copper sulfide-containing mineral.