Investigation Of Ultrasonic Assisted Cyanide Leaching Gold

The development and utilization of refractory gold mines is the only way to meet the rapid growth of China's gold demand.However,the problem of enveloping of ore and process products,and the "grab gold" problem of carbonaceous materials in the leaching process,are the main reasons for the difficulty recovery of gold in efficient,long process time and high energy consumption.In this study,the gold in the immersion gold leaching of ultrasoniccyanide was explored.The effects of initial solution concentration,ultrasonic time,ultrasonic power and solution volume on cavitation threshold and cavitation intensity are studied by ultrasonic irradiation of Fe2+ solution and KI solution.By comparing the changes of the solution concentration of sodium cyanide solution after ultrasonic irradiation and natural standing separately,this paper explores whether the ultrasonic wave can promote the decomposition of sodium cyanide.By introducing ultrasonic waves into the cyanide leaching system of GLZ carbonaceous gold ore and LB coated copper-gold ore,this paper studied the effects of experimental parameters such as ultrasonic time,ultrasonic power and initial sodium cyanide concentration on gold leaching.The factors affecting the cavitation threshold and cavitation intensity of ultrasonic wave in Fe2+solution and KI solution were explored.The results show that the cavitation effect occurs even at an ultrasonic power of 10 W,so the cavitation threshold is not accurately measured,but it shows that the ultrasonic action is prone to cavitation in aqueous solution;For cavitation intensity,the most influential experimental parameter is the ultrasonic action time.As the ultrasonic action time increases,the cavitation intensity increases significantly.The results of the study on the decomposition of sodium cyanide indicate that the temperature and ultrasonic action time have the greatest influence on the decomposition of CN-,followed by the ultrasonic power,and the initial sodium cyanide concentration has the least influence on the decomposition of CN-.Ultrasonic irradiation of sodium cyanide solution does not additionally promote the decomposition of sodium cyanide compared to the decomposition of sodium cyanide in the natural state.Taking the GLZ carbonaceous gold ore and LB-coated copper-gold ore as research obj ects,the leaching of gold during cyanide leaching and ultrasonic-cyanide leaching were studied.When the leaching time is 30 min for GLZ carbonaceous gold ore,the leaching rate of conventional cyanide leaching gold is 56.3%,while the leaching rate of ultrasonic-cyanide synergistic leaching gold is 68.7%.When the leaching time was 60 min,gold leaching rates for conventional cyanide leaching and ultrasonic-cyanide synergistic leaching were 66.7%and 67.8%,respectively.Therefore,although ultrasonic assisted cyanide leaching does not significantly increase the maximum leaching rate of gold in GLZ-containing carbonaceous gold ore,it accelerates the chemical reaction rate and shortens the leaching time.When the leaching time is 4h,8h,16h for LB-wrapped copper-gold ore,the leaching rates of conventional cyanide leaching gold are 28.4%,33.6%and 36.1%,respectively;When the other conditions were the same,the leaching rate of gold leaching was 44.5%after 4 hours of synergy with the cyanidation method by 600 W ultrasonic wave.Therefore,ultrasonic assisted cyanide leaching increases the leaching rate of gold in LB-coated copper-gold ore and accelerates the chemical reaction rate.