Abstract:

In this paper, the comprehensive recovery technology for gold concentrate containing Au 140-150 g/t, Ag 900-1,000 g/t, Bi 9.0%-10.0% and Cu 14%-17% was studied by heap-leaching with bacterial oxidation and chemical process. In preliminary test, the technology that bacterial oxidation leaching of Cucyanidation leaching of Au and NaCl-FeCl₃-HCl method leaching of Bi and Ag was found out by the stirred experiment. This technique was applied to leach of Au, Ag, Cu and Bi in the column experiment. The parameters in column experiment were testified to be steady and reliable in scale-up test. The penetrability of concentrate was improved by mixing the coarse sand into concentrate; The copper endurance of the bacterial was increased by acclimation, up to 30 g/L. The leaching solution of NaCl-FeCl₃-HCl system may be used repeatedly because Fe²⁺becomes Fe³⁺ in solution by the H₂O₂ oxidation, and Ag, Bi may be leached simultaneously. The recovery rate of Au, Ag, Cu and Bi is 92.98%, 65.09%, 45.33%, 53.49% respectively.

Key words: gold concentrate containing Cu, Bi, and Ag, heap leaching, comprehensive recovery, bacterial oxidation, NaCl-FeCl₃-HCl system