Bioleaching Of Copper Sulfide Mineral And Mechanism Analysis

Copper is a kind of base metal that is used wildly.which is now in great demand With the development of economy,the market demand for copper increases year by year.Copper metallurgical technology has developed rapidly in recent years,while the copper ore resources in China is limited,which results in the supply nervous of copper metallurgical raw material.The grade of copper in the ores decreases from a few percent in the early twentieth century to a few thousandths now,and the traditional technics could not make the best use of low grade ores.Therefore,it is very important to develop a new technology to treat the low grade copper ore.Bioleaching,compared with traditional metallurgy technology,has many advantages like low investment,low cost,low pollution and so on.It can treat low grade copper ores also.Most of the copper ores in China are sulfide ores.In proven reserves,87%of copper ores is sulfide ores which mainly includes chalcocite,chalcopyrite,bornite,etc.The oxidized copper ore accounts for 10%and the mixed ore accounts for only 3%.So,further study on bioleaching of sulfide copper mine can provide theoretical and industrial guidance for copper production in the future.In this thesis,the bioleaching study of chalcopyrite,bornite,chalcocite whose pulp density are 1%,3%,5%was carried out.The results showed that leaching rate of chalcopyrite,bornite,chalcocite were 30.09%,97.38%,99.21%respectively when pulp density was 1%;The leaching rate were 28.58%,94.42%,97.56%when pulp density was 3%respectively;The leaching rate were 27.83%,91.25%,96.13%respectively when pulp density was 5%;The leaching rate of no-bacterias system were 13.56%,73.59%,75.69%respectively when pulp density was 5%.The leaching rate of chalcocite,chalcopyrite and bornite in bacteria containing system improved significantly compared with no-bacterias system.Primary principle analysis of sulfide copper mine was conducted in this paper.MS software was use to simulate the crystalline structure of three kinds of copper,test the stypticity of mineral single cell and calculate the total bond energy and bond length.The results showed that the total bond energy of chalcopyrite,bornite,chalcocite super cell were743.55eV,475.0eV and410.96eV respectively,decreasing systematically,which showed that the energy required to break the key reduced gradually.There were two kinds of bonding effect in chalcopyrite supercell S-Fe and S-Cu respectively;There were two kinds of bonding effect S-Cu,S-Fe and three kinds of antibonding Fe-Fe,Cu-Fe and Cu-Cu in boraite supercell;There were a kind of bonding effect S-Cu and a kind of antibonding Cu-Cu in chalcocite supercell.After simulating the crystal structure of sulfide copper mine,state density and projection state density of mineral super cell were calculated to discuss the mechanism of biological leaching experiment from the atomic level.The results showed that the energy difference between the Fermi level and conduction band bottom as well as the width of forbidden band decreased gradually in chalcopyrite,bornite and chalcocite.When the redox occured,it was easy for the valence electrons to get through the forbidden band and reached to high-energy empty orbit.So the electron capture ability of empty orbit with high energy weaken gradually,which results to the increase of reducibility macroscopically.In redox system,because of the existence of high oxidizing Fe3+,the mineral with better reducibility was easier to be leached.The theoretical analysis and the experiment results were consistent.