Preprocessing Of Gold Powder From Somewhere Of Hunan And Thiourea Leaching Process Research

Along with the gold ore resources which are easy to process are dring up day afterday,refractory gold ore has become an important new resource,gold sulfide ore has the thehighest rate among them.The development and utilization of this kind of gold mineralresources is of far-reaching significance in our country.Pretreatment for the refractory goldore before the leaching becomes the common method to improve the refractory gold oreleaching rate.The thiourea leaching of gold and other non-cyanide leaching method also causemore and more attention.The sample of this research is choosed from somewhere of Hunan gold powder afterreelecting,and the proeess mineralogy of the gold is researehed in detail.The grade of thisgold is81.5g/t.The main compositions of this gold are pyrite, galena, sphalerite, magnetite,hematite, quartz and so on.Due to the high content of pyrite,with the microgranular goldoccurrence in pyrite and quartz or package,which make this gold mine belongs to refractorygold ore.Preprocessing before the leaching becomes the common method to improverefractory gold ore leaching rate.So we choose roasting-oxidation,nitric acid atmosphericoxidation,nitric acid pressure oxidation and so on,and research the conditions of thiourealeaching gold.Test sample directly thiourea leaching is studied in the first place,but the leaching rate isnot high.Then we study the influence of different roasting temperature，roasting time andoxygen on the gold leaching rate,and determine the optimum process conditions of roastingpretreatment is800℃，2hours and ajar fire door,the highest leaching rate can be70.73%;westudy the influence of different nitric acid atmospheric oxidation time on gold leachingrate,and determine the best pretreatment conditions to the nitric acid atmospheric pressure is2hours,the highest leaching rate can be69.07%;we study the influence of different nitric acidpressure oxidation time and the concentration of sodium lignin sulfonate on gold leachingrate,and determine the best pretreatment conditions to the nitric acid pressure pretreatment is3.5hours and1.25g/kg sodium lignin sulfonate,,the highest leaching rate can be93.40%.The three pretreatment methods can significantly improve the leaching rate of the refractory gold ore,nitric acid pressure pretreatment is obviously better than the other two kinds ofpretreatment method.Although the demand of nitric acid pressure pretreatment to the equipmentis higher,But also the pollution to the environment is minimum.Finally we choose the nitric acidpressure oxidation as the best pretreatment method.