Heap-leach pad injection system and method

Abstract

In one embodiment, the present disclosure provides an extraction method. A conduit is formed in a heap-leach pad. The heap-leach pad includes a plurality of poorly perfused areas. The conduit is in fluid communication with poorly perfused areas of the heap-leach pad. A fluid that includes steam is injected into the conduit. The fluid travels through the heap-leach pad and condenses in poorly perfused areas of the heap-leach pad. An extraction solution is applied to the heap-leach pad. Condensation of steam in the poorly perfused areas of the heap-leach pad provides new flow pathways for the extraction solution.

What is claimed is: 
     
         1 . An extraction method comprising:
 in a heap-leach pad comprising a plurality of poorly perfused areas, forming a conduit in a heap-leach pad, the conduit in fluid communication with the poorly perfused areas of the heap-leach pad;   injecting a fluid comprising steam into the conduit, the fluid contacting, and the steam condensing in, the poorly perfused areas of the heap-leach pad; and   applying an extraction solution to the heap-leach pad;   wherein condensation of steam in the poorly perfused areas of the heap-leach pad provides new flow pathways for the extraction solution.   
     
     
         2 . The method of  claim 1 , wherein the extraction solution comprises cyanide. 
     
     
         3 . The method of  claim 1 , wherein the extraction solution comprises an acid, a base, or other chemical or biological component that facilitates release of metals or chemical compounds from rock. 
     
     
         4 . The method of  claim 1 , wherein the fluid comprises heated steam. 
     
     
         5 . The method of  claim 1 , wherein forming a conduit in a heap-leach pad comprises forming a plurality of conduits in the heap-leach pad. 
     
     
         6 . The method of  claim 5 , wherein forming a plurality of conduits in a heap-leach pad comprises drilling boreholes in the heap-leach pad. 
     
     
         11 . The method of  claim 5 , wherein the conduits are formed in a grid. 
     
     
         12 . The method of  claim 5 , wherein the conduits are formed in an irregular pattern. 
     
     
         13 . The method of  claim 1 , wherein forming a conduit in the heap-leach pad comprises drilling a borehole in the heap-leach pad. 
     
     
         14 . The method of  claim 1 , wherein the poorly perfused areas comprise dry areas. 
     
     
         15 . The method of  claim 1 , wherein the method is carried out in the absence of an extraction well to remove injected fluid. 
     
     
         16 . A mine closure or remediation method comprising:
 in a heap-leach, forming a conduit in a heap-leach pad, the heap-leach pad comprising dissolvable or oxidizable minerals; and   injecting a fluid comprising steam into the conduit;   wherein the steam contacts the minerals and enhances oxidation or dissolution of the minerals.   
     
     
         17 . The method of  claim 16 , wherein the minerals comprise sulfides and the steam enhances sulfide oxidation.