Research On Enhanced Leaching Process Of High Arsenic And High Sulfur Gold Concentrate Pretreatment At Room Temperature And Pressure

In recent years,a large number of gold mine resources have been developed,and the number of gold mines in China which is high-grade and easy-to-leaching is gradually being exhausted.Gold mines of low-grade,complex and difficult-to-extract have gradually become the main source of resources for the current gold industry.Gold mines containing high arsenic and high sulfur are one of the most common and widely distributed types of gold mines that are difficult to leaching in China.The accompanying impurities such as S and As in this type of gold mine are too high,and gold minerals are wrapped in arsenopyrite and pyrite in the form of inclusions,which makes it impossible for the gold minerals to directly contact the leaching agent,making it difficult to obtain good leaching results.Therefore,choosing a suitable pretreatment technology to open the inclusions of gold minerals is an important method to improve the leaching effect of difficult-to-extract gold ore and to achieve a leap in technical indicators for gold resource extraction.This paper takes a high-arsenic and high-sulfur gold ore in Myanmar as the research object.Firstly,conducting detailed process mineralogical research through multi-element chemical analysis,X-ray diffraction analysis,MLA analysis,electron probe analysis,and electron microscope analysis to systematically study the elemental composition,mineral composition,mineral intercalation characteristics,symbiosis relationship,and gold occurrence state of this gold ore.Under the guidance of technological mineralogy research results,the gold concentrate was leached through alkaline pretreatment(sodium hydroxide)-green gold extraction agent(Jinhu 1#)under normal temperature and pressure.By optimizing the pretreatment and gold leaching process and conditions,a good gold leaching effect was finally achieved.Process mineralogy research shows that the gold ore contains 31.47g/t Au,and the contents of other main elements As,Fe and S are 26.02%,32.93% and 26.20% respectively.The main mineral composition of the gold mine is pyrite and arsenopyrite,the contents of which are57.30% and 28.28% respectively.Natural gold and electrum are the main gold-bearing minerals and the distribution rates of gold in this two kinds of minerals are 34.91% and 50.65%.The distribution rate of gold in sulfides such as arsenopyrite and pyrite in the form of lattice substitution is 14.29%.The grain size of natural gold and electrum is fine,and the cumulative distribution rates of the two in the-19?m size class are 95.75% and 83.61% respectively.In addition,natural gold and electrum are closely packed with pyrite and arsenopyrite.The proportions of the inclusion particles of the two are 62.50% and 53.13%,and the monomer particles are only 15.50% and 15.63%,respectively.The direct leaching process is used to treat the gold ore,and the leaching rate of gold is only 46.81%,so in the paper,the "alkali leaching pretreatment-gold leaching" process is used to treat this gold ore.The optimal pretreatment condition determined by the pretreatment condition experimental study is: grinding for 20min(-38?m fraction accounts for 92.95%),liquid-solid ratio is 6:1,sodium hydroxide,pretreatment catalyst ZNT and pretreatment oxidant are added in the mill,leaching under pH=13,and the amount of catalyst ZNT is 10 kg /t,the amount of hydrogen peroxide is 40kg/t,and the pretreatment time is 12 h.The pretreatment process under above optimal conditions combined with the gold leaching stage(leaching for 24 h,leaching under pH=13,the dosage of Jinhu 1# is 20kg/t)can achieve a gold leaching rate of 78.69%.The optimal gold leaching conditions determined by optimizing the gold leaching process are:leaching for 8h,the dosage of Jinhu 1# is 20kg/t and leaching under pH=13.Under the above conditions,the gold leaching rate is 77.99%.Although the optimization of the conditions for the gold leaching process failed to significantly increase the leaching rate of gold,the optimization of the leaching conditions significantly shortened the leaching time,controlled the amount of leaching agent,and significantly improved the leaching efficiency.Through the exploration and research on the multi-stage leaching process,the best leaching process is determined as "primary pretreatment-primary leaching-secondary pretreatment-secondary leaching",and finally this process can obtain a leaching rate of 87.57%.In this paper,a systematic process mineralogy research,process optimization of pretreatment and gold leaching are carried out.Based on these,the successful leaching of a high-arsenic and high-sulfur gold mines in Myanmar is achieved through conventional alkaline pretreatment combined with the green gold extracting agent Jinhu 1# under normal temperature and pressure.This has contributed to the advancement of green and efficient gold extraction technology for this type of difficult-to-extract gold resources.