Research On Pretreatment And Oxidation Kinetics Of High-sulfur And High-Arsenic Refractory Gold Concentrate By Fenton Agent In Acid Medium

With increasingly exhausting of easily leachable gold ores,the development and utilization of high-sulfur and high-arsenic refractory gold ores have attracted extensive attention around the world.In China,the resource of refractory gold ores containing high sulfur and high arsenic is very abundant and extensively distributed.Therefore,it is practically meaningful to explore better methods to utilize the refractory gold ores at the present and in the future of China.Most important thing of developing this type of mineral is the choice and application of pretreatment method.This will directly relate to the leaching rate of gold,cost, environmental protection and so on.In this paper,the high-sulfur and high-arsenic refractory gold concentrate ores from Sanmenxia in Henan province used as the test materials,and Fenton reagent as the oxidant.The technological condition and oxidation kinetics of the reaction process in acid medium were studied.The factors affecting the pretreatment process were examined.With orthogonal experiments,the optimum condition was obtained under the conditions: pretreatment temperature(313K),concentration of pulp(20g/L),initial concentration of sulfuric acid(0.7mol/L),initial concentration of hydrogen peroxide(6mol/L).According to their significance to the dissolved ratio of Fe,the descending sequence of above factors is concentration of pulp,initial concentration of hydrogen peroxide,initial concentration of sulfuric acid, pretreatment temperature.The dissoved ratio of element Fe can be high to 99.58% under the best condition.The oxidation mechanism of the reaction was analyzed preliminarily.The X-ray diffraction(XRD),LV scanning electron microscopy(SEM) and Energy Dispersive Spectrometer(EDS) adopted to the ores before and after the pretreatment respectively.Through analysis and comparison,this method of pretreatment by Fenton agent is better applied to ores including relatively high arsenic concentration.ICP-AES used to analyse the chemical component of the liquid after the pretreatment,Au was not found in the liquid.So this method can effectively remove the sulfide minerals which wrapped the gold and provide benefit conditions for the following cyanization leaching.Finally,on the basis of above experiment,the dissolved rate of Fe was studied.And this paper concluded that the oxidation kinetics of Fe conforms to the surface reaction model and the apparent activation energy is 46.39kJ/mol.The overall condition was controlled by chemical-reaction controlled process.The method for pretreatment high-sulfur and high-arsenic refractory gold ores is under mild condition,environmental friendly and can saving much time for oxidation compared to conventional pretreatment.Also the raw materials and the products were non-toxic,and the process does not produce harmful gases.This is a clean process,which meets the environmental protection requirement.The test results provide a practical method for the pretreatment and development of similar high-sulfur and high arsenic refractory gold concentrate.However,it is necessary to be further researched and technical improved before industrial applications.