Studies On The Leaching Process Conditions Of Chalcocite In Acidic System

In this dissertation, the leaching process of chalcocite was studied, using H2O2 or O2 as oxidizing agents,Fe2(SO4)3 as catalyst and NaCl as assistant leaching agent in the sulfuric acid solution. The influence of reaction temperature, reaction time and concentration of iron sulfate etc. on the leaching rate of copper in chalcocite were investigated in order to obtain the optimized process conditions. SEM, EDS and XRD were used to character the raw ore and leaching residues to reveal the leaching mechanism of chalcocite.The main research work includes:(1) When using hydrogen peroxide as oxidizing agent, taking the leaching rate of copper in chalcocite as the main indexes, the leaching conditions of chalcocite were investigated through single-factor experiments and orthogonal experiments and the optimized conditions were as following: the reaction temperature 85℃, the reaction time 210min,the concentration of ferric sulfate, hydrogen peroxide, sodium chloride and sulfuric acid are 0.25, 0.2, 0.5 and 0.5 mol/L respectively. The repeated experiments results showed that the average leaching rate can reach 95.69%.(2) When using oxygen as oxidizing agent, taking the leaching rate of copper in chalcocite as the main indexes, the leaching conditions of chalcocite were investigated through single-factor experiments and orthogonal experiments and the optimized conditions were as following: the reaction temperature 80℃, the reaction time 240min,the flow rate of oxygen Q.6mol/min, the concentration of ferric sulfate, sodium chloride and sulfuric acid are 0.05, 0.5 and 0.5 mol/L respectively. The repeated experiments results showed that the average leaching rate can reach 95.21%.(3) Under the optimized conditions, the changing trend of compositions and contents of Cu&S in the leaching residues after different leaching times were obtained by XRD and EDS analysis to reveal the leaching mechanism of chalcocite. When using hydrogen peroxide as oxidizing agent, the new phases in the leaching process included Cu1.96S(djurleite),Cu1.8S(digenite),Cu1.75S(anilite),Cu1.4S(spionkopite) and Cu9S8(yarrowite). Furthermore, the reaction model of chalcocite is not entirely shrinking core model, since the new phase particles distribute randomly. The leaching reaction process of chalcocite may be described as: Cu2S→Cu1.96S-Cu9S5 (Cu1.8S) →Cu7S4 (CU1.75S)→Cu39S28(Cu1.4S)→Cu9S8(Cu1.12S)→CuS→S While using oxygen as oxidizing agent,the similar conclution can be obtained, but a new pahse Cui.6S(Geerite) was observed in the leaching residues.