Selective reduction of cupriferous calcine

Abstract

A process for selectively reducing calcine from a copper/nickel containing sulfidic material includes subjecting the calcine to a mildly reducing atmosphere at relative high temperatures. CuO is selectively converted to Cu 2 O which can easily be separated by leaching from other metals which may be present in the material.

1 . A process for recovering copper from sulfide-containing material which contains, in addition to copper, at least one other metal selected from the group consisting of iron, nickel and cobalt, comprising roasting said material for sufficient time to provide a substantially sulfur-free calcine, subjecting the calcine to sufficient heat and a reducing atmosphere to selectively reduce CuO in the calcine to Cu 2 O and form a reduced calcine, subjecting the reduced calcine to an oxidizing leach and recovering the copper.  
     
     
         2 . A process according to  claim 1  wherein the reducing atmosphere is characterized by a partial pressure of oxygen sufficiently low to reduce CuO to Cu 2 O, but no so low as to reduce NiO to Ni metal.  
     
     
         3 . A process according to  claim 1  wherein the reducing atmosphere is characterized by pO 2 ˜10 −10 .  
     
     
         4 . A process according to  claim 1  wherein the sufficient heat ranges from about 750° C. to about 1050° C.  
     
     
         5 . A process according to  claim 1  wherein the sulfide containing material is bessemer matte.  
     
     
         6 . A process according to  claim 1  wherein the oxidizing leach is in sulfuric acid.  
     
     
         7 . A process according to  claim 1  wherein the reducing atmosphere contains a mixture selected from the group consisting of CO/CO 2 , H 2 /H 2 O and combinations thereof.  
     
     
         8 . A process according to  claim 1  wherein the calcine is reduced in a controlled atmosphere using a fluid bed apparatus.  
     
     
         9 . A process according to  claim 6  wherein leach liquor from the oxidizing leach is subjected to electrowinning to recover the copper therefrom, and spent electrolyte from the electrowinning operation is recycled to constitute the aqueous sulfuric acid solution for leaching a further supply of reduced calcine material.  
     
     
         10 . A process according to  claim 5  wherein the bessemer matte is dead roasted to remove all the sulfur.  
     
     
         11 . A process according to  claim 4  wherein the temperature is about 1000° C.  
     
     
         12 . A process for selectively reducing CuO to Cu 2 O in a calcine which contains, in addition to copper, at least one other metal selected from the group consisting of iron, nickel and cobalt, comprising roasting said material for sufficient time to provide a substantially sulfur-free calcine, subjecting the calcine to sufficient heat and a reducing atmosphere to selectively reduce CuO in the calcine to Cu 2 O and form a reduced calcine.  
     
     
         13 . A process for selectively reducing CuO to Cu 2 O in a calcine according to  claim 12  wherein the reducing atmosphere is characterized by a partial pressure of oxygen sufficiently low to reduce CuO to Cu 2 O, but no so low as to reduce NiO to Ni metal.  
     
     
         14 . A process for selectively reducing CuO to Cu 2 O in a calcine according to  claim 13  wherein the reducing atmosphere is characterized by pO 2 ˜10 −10 .  
     
     
         15 . A process for selectively reducing CuO to Cu 2 O in a calcine according to  claim 12  wherein the sufficient heat ranges from about 750° C. to about 1050° C.  
     
     
         16 . A process for selectively reducing CuO to Cu 2 O in a calcine according to  claim 12  wherein the temperature is about 1000° C.  
     
     
         17 . A process for selectively reducing CuO to Cu 2 O in a calcine according to  claim 12  wherein the sulfide containing material is bessemer matte.  
     
     
         18 . A process for selectively reducing CuO to Cu 2 O in a calcine according to  claim 17  wherein the Bessemer matte is dead roasted to remove all the sulfur.  
     
     
         19 . A process for selectively reducing CuO to Cu 2 O in a calcine according to  claim 12  wherein the calcine is reduced in a controlled atmosphere using a fluid bed apparatus.  
     
     
         20 . A process for selectively reducing CuO to Cu 2 O in a calcine according to  claim 12  further comprising subjecting the reduced calcine to an oxidizing leach and recovering copper.