Study On The Microwave Pretreatment Of Gold Bearing High Arsenic Sulphide Concentrate

In this study, raw materials were selected for the sulphide concentrates after flotation of lead-zinc ore in Hunan, sulfur was about 50%, leaching rate was only 9.82% before pretreatment, it was a typical refractory gold ores and it needed to open inclusions of gold in the ores to effectively improve the leaching rate. Along with the national requirements was improved for environmental protection and energy efficiency, although the traditional roasting can collect tail gas, energy consumption was high and utilization ratio of energy was low. More efficient methods were needed in pretreatment. Treatment on the microwave of refractory gold ores has been carried out some research at home and abroad, but there was no practical guidance when face to so high sulfur. This paper explored the basic conditions of microwave roasting, and considered the perspective of environmental protection and the tail gas in time. Non cyanide leaching of gold was a hot research topic in recent years in the field. To avoid the use of cyanide process or other toxic leaching agent, this study adopted the method of relative safety and environmental protection of the iodide leaching of gold, while leaching conditions were optimized, and it provided reference for the industrial application of iodide method. The main contents of this paper were followed:(1) The ore of high arsenic gold concentrate, which was analyzed of chemical composition and particle distribution of the product of sulphide concentrate, the content of S and Fe was 49.93% and 41.86%, respectively. The particle size of ore was less than 200 accounted for 70%. The XRD analysis showed that the metal ore, mineral mainly consists of pyrite(Fe S2), the diffraction intensity of other minerals was very weak, and the main gangue mineral was quartz.(2) Phase analysis showed that, high arsenic gold concentrate wrapped in metal mineral was the most of the non single gold and the proportion was 98.57%. Analyzed by the TGA and DTGA, the sample had a greater weight loss from 400℃ to 650℃ and the weight loss rate was 27%.(3) When the microwave power, reaction time, amount of ore was 16 k W, 50 min, and 900 g, respectively, the sample weight loss rate was up to 28.12%. The XRD spectrum of the sample composition had changed obviously after microwave roasting, and Fe S2 was oxidized to Fe2O3. The SEM analysis results showed that sulphide concentrate was larger particles, dense structure, and smooth surface before roasting; it became uniform particle size, loose porous, and increased specific surface area after microwave roasting.(4) After made sure of the optimal concentration of iodine, iodine and potassium iodide mass ratio, the ratio of liquid to solid, and the leaching time, the leaching rate of gold was 71.56%, and the leaching rate was only 9.82% without microwave roasting.