Research On The Leaching Process Of A Gold Mine In Yunnan By Ammonia Thiosulfate Method

The mechanism of leaching gold using ammoniacal thiosulfate solution has high leaching speed,high leaching rate and low toxicity.In particular,this method is not sensitive to the certain impurities in the gold ore,which is a non-cyanide leaching method with broad prospects.The gold mine in Yunnan was leached by thiosulfate method in the paper.The research focused on copper sulfate concentration,ammonium sulfate concentration,thiosulfate dropping method,thiosulfate concentration,p H value and dissolved oxygen,etc.on effect of the concentration of tetraammoniated copper,ammonia,thiosulfate in leaching solution and gold leaching rate.The mechanism of action between them was preliminarily explored.The test results show the appropriate dissolved oxygen concentration and the dosing method have a significant effect on reducing the thiosulfate consumption rate and increasing the gold leaching rate effect.In the gold leaching system,the suitable leaching conditions are p H=9.5,1.3mmol/L copper sulphate,0.125mol/L ammonium sulfate,and 0.15mol/L thiosulfate.At the beginning of leaching,the sodium thiosulfate solution was added to the leaching system at a rate of 0.8 m L/min,and no gas was filled during the leaching process.After leaching for 6 hours,the gold leaching rate was 88.57%.Compared with the leaching rate of 84.30% after 36 h cyanide leaching,the leaching time of the thiosulfate method is greatly shortened and the gold leaching rate is improved.The purpose of low reagent dosage and high leaching rate was realized.The dissolution kinetics of gold was studied under better experimental conditions.Within one hour of leaching,the dissolution of gold is mainly diffusion controlled.After one hour leaching,the reaction was found to be chemically controlled.This paper has obtained good indicators in the experimental study of leaching an actual gold mine in Yunnan.It provides technical and theoretical references for rare metals.