Heap leach is a method developed by Henin and Lindstrom to process low-grade ore on a large scale with small production cost so that the levels below the cut-of grade can still be economical. Heap leach is the process of leaching of low grade gold rocks thrown, then the solution containing the metal particles are screened and separated by electrolysis. Heap leach done repeatedly and on a large scale.
There are several steps that are used in processing gold ores using heap leaching system
  • Preparation of the foundation of leaching with an angle of 1 degree to 6 degrees. : The foundation of this leaching can be made by permanently using a hardening of the concrete floor or foundation and geo-coated membrane (High Density Polyethylene)
      • Then the rock minerals that have been taken from the mine area was destroyed. Destruction of rock done to get smaller sized rocks. Size obtained usually ± ½ or up to 1 inch. machines used in the process of destruction is the engine or Stone Mill Hammer Crusher and Crusher Jaws.
      • After the material to be crushed and refined, then placed into the foundation of leaching that has been provided 
      • Then through the spray in the spray solution of sodium sianide. And in general the use of sodium sianide NaCN. This process aims to take the gold extraction is formed in the chlorination process and transformed into compounds Dicyano Aurrat (Au (CN) 2). Because the compound that would be too absorption within the pores of activated carbon

        In the cyanidation process consists of two important stages, namely the process of dissolution and separation of gold from the solution process. Solvents commonly used in the process cyanidasi is NaCN, KCN, Ca (CN) 2, or a mixture of all three. The solvent most often used is NaCN, being able to dissolve gold better than any other solvent.
        From this it will spray cyanide in the extraction process produces a chemical reaction in the form:
         Au + NaCN + O2 + H2O = NaAu (CN) 2 + NaOH (from equation Elsener and Adamson)
         Au + NaCN + O2 + H2O = NaAu (CN) 2 + H2O2 + NaOH (from equation Adamson)