| In recent years, with easily leachable gold resources gradually consumption and the gold price soaring, how to exploit and use refractory gold resources becomes the focus of attention. China is rich in reserves of gold resources, and especially the arsenic-sulfur containing refractory gold ores is the most common. At present, the utilization of this kind of gold ores is not optimistic, and there are a serious of problems such as heavily polluted, high cost and low gold recovery. So to strengthen the exploitation of this kind of gold ores is provided with great practical and economic significance.In this study, the sulfur concentrate containing gold and arsenic which was provided by a lead-zinc mine in Hunan was used as the raw material. Sulfur and arsenic were removed from the concentrate and the package of sulfur minerals to gold was opened by oxidizing roasting. With this method, the negative influence of sulfur and arsenic to cyanide leaching process was reduced and a better quality of oxidizing roasting cinder could be got. To recover gold from oxidizing roasting cinder, two different kinds of technology were put forward. The one is removing part of lead, zinc, arsenic which are harmful to cyanide leaching performace by NaOH solution and leaching gold by cyanide solution from alkali leaching residue. The other is smelting pig iron to enrich gold with reduction and making gold and iron separation by electrolysis.This article has comprehensively studied the first process, and the reserch on ironmaking which is a part of the second process was carried out and its feasibility was preliminarily verified too. Firstly, the air flow of roasting process was calculated, and the influence of the roasting temperature, time on the sulfur and arsenic removal rate and the gold cyanide leaching rate were studied. Secondly,the effect of temperature, liquid-solid ratio, sodium hydroxide concentration, time of NaOH leaching process on the leaching rate of lead, zinc and arsenic and the cyanide leaching rate of gold were researched. It was also detailedly investigated that the impact of temperature, time, liquid-solid ratio, pulp pH, and the dosage of sodium cyanide of cyanide leaching process on gold leaching rate. And the promoting role of H2O2in cyanide leaching process was analyzed and explored. Lastly, the effects of carbon to oxygen mass ratio together with slag binary basicity, smelting temperature and smelting time, on the recoveries of iron and gold were evaluated.The results showed that under the best roasting conditions of air flow of1.32m3/h, temperature of700℃and time for2h, sulfur and arsenic removal rate was respectively reach to99.47%and89.22%,and Au leaching rate is75.58%. At a temperature of80℃, liquid to solid ratio of3:1, NaOH concentration of2mol/L, leaching time of2h, leaching rate of lead, zinc and arsenic were41.70%,50.73%and27.19%. After alkaline leaching process, the gold leaching rate has been improved from57.68%to76.64%. When under the conditions of temperature of15℃(room temperature), liquid to solid ratio of3:1, the pulp pH of10.5, NaCN dosage of3kg/t ore, and the leaching time of24h, the gold cyanide leaching rate was76.64%, and it could be increased about20%by fine grinding. Under the same conditions with direct cyanide leaching process, the time of cyanide leaching process reduced to6-8h from originally of24h, and gold leaching rate increased by5%after the hydrogen peroxide being added in. And when achieved the same gold leaching rate, the dosage of NaCN reduced to2.25kg/t ore. The optimal conditions of ironmaking process were determined to be as follows:carbon to oxygen mass ratio0.93, slag binary basicity1.0, smelting temperature1500℃and smelting time90minutes. Under the optimal conditions, the recoveries of iron and gold reached97.49wt.%and99.1wt.%, respectively, and the composition of pig iron obtained was analyzed chemically to be as follows:gold16g/t; iron97.27wt.%; carbon1.38wt.%. The gold content in the pig iron was about1.63times of that in the cinder. |
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