Heap leach

Abstract

An improved heap leach process for the bacterial heap leaching of base metal sulphide ores, the process including the addition of elemental sulphur to the ore, whereby sulphur oxidising bacteria indigenous to, or added to, the ore may oxidise the elemental sulphur and generate heat within the ore heap.

1 . An improved heap leach process for the bacterial heap leaching of base metal sulphide ores containing a mineral or an assemblage of minerals that require temperatures higher than ambient for efficient oxidation of at least one of the minerals present, the process characterised by the addition of elemental sulphur to the ore, whereby the elemental sulphur is oxidised by mesophilic bacteria present in the ore heap, this oxidation of elemental sulphur generating heat and raising the internal temperature of the heap upwardly such that thermophilic bacteria can operate.  
   
   
       2 . A process according to  claim 1 , wherein chalcopyrite comprises the predominant sulphide mineral in the ore.  
   
   
       3 . A process according to  claim 1 , wherein the blending or addition of elemental sulphur to ore provides between about 2 to 20% elemental sulphur to ore (w/w).  
   
   
       4 . A process according to  claim 1 , wherein the addition of elemental sulphur to a process for the bacterial heap leaching of base metal sulphide ores generates sulphuric acid through the oxidation of elemental sulphur, in addition to the generation of heat.  
   
   
       5 . An improved heap leach process for the bacterial heap leaching of base metal sulphide ores containing a mineral or an assemblage of minerals that require temperatures of greater than 45° C. for efficient oxidation of the or each mineral, the process characterised by the addition of elemental sulphur to the ore, whereby the elemental sulphur is oxidised at temperatures lower than about 45° C. by mesophilic bacteria present in the ore heap, this oxidation of elemental sulphur generating heat and raising the internal temperature of the heap upwardly such that thermophilic bacteria can operate.  
   
   
       6 . A process according to  claim 5 , wherein chalcopyrite comprises the predominant sulphide mineral in the ore.  
   
   
       7 . A process according to  claim 5 , wherein the blending or addition of elemental sulphur to ore provides between about 2 to 20% elemental sulphur to ore (w/w).  
   
   
       8 . A process according to  claim 5 , wherein the addition of elemental sulphur to a process for the bacterial heap leaching of base metal sulphide ores generates sulphuric acid through the oxidation of elemental sulphur, in addition to the generation of heat.  
   
   
       9 . (canceled)