The Study Of Thiosulfate Leaching Of Limestone Gold

In our work,the grain composition,chemical composition and mineral composition of limestone gold have been studied through XRD and XRF.The thiosulfate leaching of gold ore has been investigated.The parameters such as copper concentration,thiosulfate concentration,ammonia concentration,temperature,initial pH and time have been optimized.In order to increase the gold extraction,the oxidized roasting and microwave roasting of gold ore,including roasting temperature and time,have been studied respectively.The mechanism of leaching has been explained through TG-DTA,SEM and XRD.Finally,the effect of free carbon on thiosulfate leaching has been studied.The results indicate that the 74.16%of gold extraction can be achieved under the condition of 0.01 mol/L copper concentration,0.5 mol/L ammonia concentration,0.1 mol/L thiosulfate concentration,5 h time,initial pH 11,temperature 50?.The higher free carbon does not favor the gold extraction.The results indicate that the oxidized roasting can lead to the decomposition of calcium carbonate and decrease the gold extraction due to the increase of pH.On the contrary,the microwave roasting can increase the gold extraction.The 90.20%of gold extraction can be achieved under the condition of temperature 500? and time 30 min.According to the XRD study,the mineral composition is not changed after the microwave roasting.The DSC-GTA show that thermal properties of gold have been changed through microwave roasting.According to the SEM-EDS study,the morphology is not changed after the microwave roasting.The distribution of particle size has been changed and there are cracks existing on the ore surface.The gold extraction can been increased due to the increase reaction chances between the gold and leaching solution.