Abstract:

A pretreating process of pressure leaching in acidic sulfate and nitrate solution and combined with sequent pressure leaching of the residue in a Ca(OH)₂ or ammonia solution for a refractory gold concentrate contain ing high As and Sb was proposed and investigated.The factors that affected pressure acidicor alkaline leaching were tested and discussed.Experimental results indicated that over 90% of gold was cyanided after pretreating by the combined process under optimized conditions.In contract,nearly zero percent of gold was extracted in direct cyanidation of the refrectory gold concentrate.On the other hand,a new extractive process of gold from the residue of acidic pressure leaching of the refractory concentrate was developed.In this extractive process the residue containing elemental sulfur was suffered by pressure leaching in a Ca(OH)₂  solution at a controlled pH range.The chemical process was described,and main factors affecting gold extracted yield was tested.The extracted gold in the process was near to the cyanidation after combined pretreating.

Key words: refractory gold, contain high As and Sb, leaching in acidic and combine with sequent pressure, pressure leaching in a Ca(OH)₂, pressure leaching of the refractory gold.