Acid leaching decarbonization and following pressure oxidation of carbonic refractory gold ore

Abstract

Carbonate decomposition of carbonic refractory gold ore and the following pressure oxidation were studied. In the carbonate decomposition procedure, the effects of liquid-to-solid ratio and reaction time on decomposition ratio of carbonate were investigated. The experimental result shows that the decomposition ratio of carbonate is 98.24% under the conditions of liquid-to-solid ratio of 5:1, Fe³⁺ concentration of 20 g/L, sulfuric acid concentration of 20 g/L, reaction temperature of 80 °C and reaction time of 2 h. Then, the slurry obtained from carbonate decomposition was put into the titanium autoclave for pressure oxidation leaching. Effects of liquid-to-solid ratio, temperature, time and oxygen partial pressure on sulfur oxidation ratio were studied during pressure oxidation. With the prolonged time, pyrite and arsenopyrite are oxidized to ferric subsulfate, hydrated ferric sulfate and jarosite, resulting in the increasing residue ratio. The residue ratio and the sulfur content in the residue can be decreased by ferric subsulfate dissolution. The oxidation ratio of the sulfur is 99.35% under the conditions of oxidation time of 4 h, temperature of 210 °C, oxygen partial pressure of 0.8 MPa and stirring speed of 600 r/min.

Keywords

carbonic refractory gold ore / carbonate decomposition / pressure oxidation / ferric subsulfate dissolution

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