A Study On The Mechanical Activation Leaching Of The Chalcopyrite And The Activation Mechanism

Chalcopyrite is one of the most important raw material for the copper industrial production.Meanwhile,chalcopyrite is the most refractory copper sulfides for leaching.According to the present research,there still exist two problems in the hydrometallurgy of the chalcopyrite.One is the low leaching rate of the chalcopyrite during leaching in sulfuric solutions at ambient temperature and pressure.The other is the controversial mechanism of the oxidative leaching of the chalcopyrite.This study discussed the influence of the reaction temperature,sulfuric acid concentration and oxidants to the oxidative leaching of the chalcopyrite and optimized the process parameters.Then the electrochemical mechanisms of the oxidative leaching of the chalcopyrite in sulfuric acid system was studied using the electrochemical measurement technologies.And this study discussed the feasibility of the mechanical activation for improving the leaching rate of the chalcopyrite at ambient pressure.Then the XRD,DSC-TGA and the electrochemical measurement technologies were used to clarify the mechanisms of the mechanical activation of the chalcopyrite.Compared three leaching solutions,the results indicated the leaching effectiveness of the chalcopyrite in H2SO4-H2O2 solution was better than the other two solutions at ambient temperature and pressure.Under optimized leaching conditions,the leaching rate of Cu and Fe in H2SO4-H2O2 solution were 38.4%and 55.9%,respectively.And the leaching rate of Cu in Fe2(SO4)3-H2SO4 solution were 19.2%.Then,the leaching rate of Cu and Fe in H2SO4 solution were 3.3%and 4.4%,respectively.According to the results of electrochemical tests,it could be concluded that the formation of the passive layer(Cu1-xFe1-yS2)on the surface of the chalcopyrite was the main reason for the low dissolution rate of the chalcopyrite when leaching in the sulfuric acid solution.However,the leaching effectiveness of chalcopyrite and the leaching mechanism were nearly unchanged when ferric ion was introduced into the sulfuric acid solution at ambient temperature.But when increasing the leaching temperature,the passive layer(Cu1-xFe1-yS2)on the surface of the chalcopyrite began to dissolve and the dissolution rate of the chalcopyrite was accelerated.Then,when adding H2O2 to the sulfuric acid solution at ambient temperature,there was no passive film formed on the surface of the chalcopyrite.The active dissolution took place on the surface of the chalcopyrite and the leaching mechanism was different.The results showed that mechanical activation method can significantly increase the leaching rate of chalcopyrite.After two stage mechanical activation-oxidative leaching,the leaching rate of Cu in Fe2(SO4)3-H2SO4 could reach up to 90.9%.According to the analysis results,there are two different mechanical mechanisms in the different stages of the ball minglling process.During the first mechanical activation process,the grain refinement and the lattice distortion both have important impact on the oxidative leaching of the chalcopyrite.And the second mechanical activation mainly breaks down the passive film on the surface of the primary leaching residue.Then,the main reaction product of the chalcopyrite duirng mechanically oxidative leaching process in Fe2(SO4)3-H2SO4 solution is the elemental sulfur.