Study On The Oxidative Leaching Behavior Of Cuprite In Sulfuric Acid Syste

Cuprite is one of copper oxide ores,with a copper content of up to 88.8%.Improving the utilization efficiency of cuprite is of strategic importance to the development of copper resources in China.The recovery methods of cuprite are mainly divided into the sulfidation flotation method and the leaching method.Because the copper in cuprite is Cu（I）,from the perspective of sulfidation reaction thermodynamics,the sulfur ion is difficult to react with Cu（I）,not easy to form sulfide film on the cuprite surface,xanthate is difficult to adsorb on the cuprite surface and then can not get a high flotation index.So the sulfidation flotation method can not effectively recover cuprite.The acid leaching method mainly leaching cuprite through sulfuric acid.The disproportionation reaction between cuprite and acid produces copper ion and copper simple substance,the highest leaching rate only to 50%,acid leaching cuprite is an electrochemical process,cuprite Cu（I）need to be oxidized,get electrons to improve the leaching rate of cuprite.Chlorine dioxide is a strong oxidant with high redox potential,green and non-toxic,and has good application prospects in wet metallurgy.In this thesis,the oxidative leaching of cuprite in the sulfuric acid system with chlorine dioxide as oxidant was investigated,the effects of temperature,sulfuric acid concentration,particle size,stirring speed,and other factors on the leaching kinetics of cuprite were investigated,and before and after the oxidative leaching of cuprite was investigated by AFM,SEM-EDS,To F-SIMS,electrochemistry,XPS,and other detection means.The morphology and properties were characterized to investigate the mechanism of oxidative leaching.The results of the leaching kinetics showed that the addition of the oxidant chlorine dioxide in the sulfuric acid system significantly increased the leaching rate of copper from the cuprite.The kinetic model of the leaching process was investigated and it was found that the oxidative leaching of cuprite in the sulfuric acid system was controlled by a mixing step with an apparent activation energy of 39.06 k J/mol at 20-60°C.The kinetic equation for the leaching of cuprite can be described as1/3ln（1-x）-1+（1-x）^-1/3=[k₀·（c）^3.2564·（r_o）^-1.5335·（SS）^0.7098·exp（-39.06/RT）]·t;AFM was used to analyze the changes in mineral surface morphology and roughness before and after the oxidative leaching of cuprite,and the results showed that the changes of mineral surface morphology and roughness were the greatest when chlorine dioxide and sulfuric acid acted together on the mineral surface,and the reaction of oxidative leaching was more intense,and the addition of chlorine dioxide could promote the leaching effect of cuprite in the sulfuric acid system;The acid leaching with the participation of chlorine dioxide can better extract copper from cuprite by SEM-EDS analysis of the surface morphology and energy spectrum of cuprite under different treatment methods;The XPS analysis of the cuprite under different conditions showed that the monovalent copper on the cuprite surface changed to divalent copper in the presence of chlorine dioxide,indicating that chlorine dioxide could effectively oxidize the cuprite.XPS analysis of the surface of the cuprite during the oxidation leaching reaction showed that the leached cuprite surface was still similar to the original ore.It shows that with each layer of oxidation of cuprite,sulfuric acid dissolves the newly generated copper oxide film;To F-SIMS analysis of the cuprite before and after oxidative leaching was performed,and by analyzing the normalized intensity of Cu O₂^-,O^-,SO₄^-and Cu SO₃^-,which are secondary ions.It was found that the leaching reaction of cuprite with the participation of chlorine dioxide can consume a large amount of Cu O₂^-,O^-secondary ions and generate more SO₄^-and Cu SO₃^-on the surface,this result indicates that the acid leaching of cuprite under the action of chlorine dioxide can obtain better leaching effect;The behavior of chlorine dioxide oxidation of cuprite was investigated by means of CV curves and Tafel curves.the results of CV curves showed that higher concentrations of chlorine dioxide oxidized cuprite better,and the results of Tafel curves could prove this idea.The corrosion rate of cuprite is faster at a higher concentration of chlorine dioxide,which indicates that cuprite is oxidized faster and more efficiently at higher concentrations of chlorine dioxide solution;The DFT calculation of the oxidative leaching process of cuprite was carried out with the CASTEP and Dmol³modules in Materials Studio to obtain parameters such as adsorption energy,differential charge density,density of states and the evolution of the oxidative leaching of cuprite,which was analysed and found to be more likely to occur with the involvement of chlorine dioxide.