Precious metal recovery using thiocyanate lixiviant

A method for separating precious metal from a precious metal-containing mineral material feed in which at least a portion of the precious metal is locked within one or more sulfide minerals, the method comprising:

• bio-oxidizing a heap initially comprising the mineral material feed in particulate form, during the bio-oxidizing a first portion of sulfide sulfur is oxidized;
• and
• after the bio-oxidizing, thiocyanate leaching the heap, the thiocyanate leaching comprising applying an acidic feed of thiocyanate leach solution to the heap and percolating the thiocyanate leach solution through the heap, the feed of the thiocyanate leach solution comprising dissolved thiocyanate and during the leaching precious metal is dissolved from the heap into the thiocyanate leach solution in the form of precious metal-thiocyanate complex;
• wherein during the thiocyanate leaching, a second portion of sulfide sulfur is oxidized, the ratio of the second portion of sulfide sulfur to the first portion of sulfide sulfur being at least as large as 1:10.