Patent ID: 8262770

Claim:
A method, comprising: (a) providing a precious metal-bearing material, the precious metal-bearing material comprising acid consumers; (b) floating the material to form a first fraction comprising at least most of the precious metal in the precious metal-bearing material and a second fraction comprising at least some of the acid consumers in the precious metal-bearing material; (c) pressure oxidizing at least portions of the first fraction but not the second fraction to form a pressure oxidized slurry comprising pressure oxidized residue and reactive sulfates and an off gas, wherein the pressure oxidized residue comprises at least most of the precious metal in the preciuos metal-bearing material; (d) contacting the off gas with at least a portion of the second fraction to cool the off gas and heat the at least a portion of the second fraction; (e) contacting the heated at least a portion of the second fraction with at least a portion of the pressure oxidized slurry to neutralize, at least partially, reactive sulfates in the at least a portion of the pressure oxidized slurry; (f) contacting the pressure oxidized residue with an alkaline lixiviant to dissolve at least most of a selected precious metal in a pregnant leach solution; and (g) thereafter recovering the dissolved selected precious metal from the pregnant leach solution.