Process Study On Iron And Gold Comprehensive Recovery From Cyanide Tailings

With the continuous development of the gold industry in China, a large amount of cyanide tailings are produced every year. The comprehensive recycling rate of these cyanide tailings is low, taking up massive land, and causing serious environment pollution. Because the cyanide tailings contains a lot of valuable metals which can be recycled comprehensively, but so far, there has no reasonable and effective method of recycling the cyanide tailings, therefore, looking for a reasonable and effective method for recycling these valuable metals in the cyanide tailings comprehensively is very urgent, which has considerable economic benefit and social environment benefit.In this paper, cyanide tailings in Zhaoyuan of Shandong province is seen as the research object, the new process of "compound additives reduction roasting-water leaching-magnetic separation" was put forward based on the systematic investigation on mineralogy, and using thiourea method to recycle gold in the tailings. The study mostly included two parts:(1) The process study of iron recovery in cyanide tailings using compound additives reduction roasting-water leaching-magnetic separation method. The effect of reduction roasting temperature, roasting time, ratio of activated carbon, ratio of compound additives, water leaching temperature, leaching time, the liquid to solid ratio and exciting current on iron recovery in cyanide tailings, the optimum conditions obtained are as follows:particle size of roasted sample after rod mill at85%less than74μm, reduction roasting temperature750℃, roasting time60min, cyanide tailings:activated carbon:sodium sulfate:sodium carbonate=100:10:10:3, rotating rate20r/min, leaching temperature60℃, leaching time5min, liquid to solid ratio15:1, and exciting current2A, the grade of magnetic iron concentrate can reach59.11%, at the same time the recovery rate of iron concentrate can reach75.12%, and the products meet the basic requirements of industrial production.(2) The process study of gold recovery in tailings using thiourea method. The effect of thiourea concentration, pH, liquid to solid ratio, leaching temperature and leaching time on gold recovery in the tailings, the optimum conditions obtained are as follows:liquid to solid ratio3:1, leaching temperature60℃, leaching time6h, Ph1-1.5, thiourea concentration2kg/t, the optimum gold leaching rate can reach82.30%.In this paper, we also make analysis to the object changes in iron recovery process using many modern analysis methods, for example, x-ray powder diffraction technique (XRD), scanning electron microscopy (SEM), energy dispersive spectrometer (EDS), and X-ray fluorescence (XRF) so on. It shows fully the change law of these major objects in reduction roasting-water leaching-magnetic separation process:In water leaching process, the soluble materials roasted by compound additives are washed out after water leaching, but the dissoluble and nonmagnetic materials enter into nonmagnetic materials after magnetic separation, one part of aluminum and silicon minerals are washed out after water leaching, other parts enter into the nonmagnetic materials, the compound additives roasting can only change the object characteristics of minerals, but the effective separation between iron and impurities can only be realized through water leaching process, causing the raising of iron grade and recovery rate. But there still exist parts of silicon impurities in the magnetic concentrate, causing the grade and recovery rate are not very high, their removal need further research.