| With the large-scale exploitation and utilization of gold resources,the gold resources which are easily dressing and smelting have dried up,and the refractory gold ores have become the main resource of gold industry today.Carlin-type gold deposit is the superior resource in Guizhou,and its gold mainly exists in the microgranular gold form wrapped in pyrite and arsenopyrite.Pretreatment is necessary to meet industrial requirements before cyanide leaching,so the non-cyanide method should be taken into consideration to leach it out by one step.Thiosulfite is one of the most environmentally protective and efficient methods of the non-cyanide gold leaching.However,researches on the high sulphur and high arsenic carlin-type gold deposit in Guizhou are not sufficient,especially,there are seldom reports about Cu2+-en-S2O32-system which uses en instead of ammonia hydroxide.Taking the carlin-type gold deposit in Guizhou as the research object,based on the theory of thermodynamics and stability constant,this thesis studies the influence rule of various factors on gold leaching rate through single-factor and orthogonal experiment,and finds out the most optimal leaching condition:the concentration of Cu2+is 0.01mol/L,the concentration of Na2S2O3 is 0.3mol/L,the concentration of en is 0.06mol/L,prepare leaching liquid by liquid-solid ratio of 4:1,leach 4h at 40?,the gold leaching rate can be up to 77.781%;after atlas analysis of leaching residue under the optimum condition by XRD,the diffraction peak of Fe S and Fe2O3 is shown in the graph,indicating the step-by-step oxidation rule of pyrite in the leaching process.Through theoretical analysis and experimental research,it is proved that the Cu2+-en-S2O32-gold leaching system which can leach the carlin-type gold deposit in Guizhou is basically feasible.And it also reveals the gold-leaching principle that the synergistic effect of the oxidant and the complexant of the sodium thiosulfate leaching... |
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