Study On Leaching Behavior And Kinetic Mechanism Of Chalcopyrite Under Oxygen Pressure Water Leaching

Chalcopyrite has an extremely stable crystal structure,and a large amount of strong oxidants are often added during the leaching process to ensure its efficient leaching,resulting in increased costs and environmental pollution.As the quality of chalcopyrite continues to decline,the content of impurity minerals such as pyrite and quartz increases,resulting in a certain uncertain effect on the leaching of chalcopyrite.Therefore,this topic selects oxygen pressure water leaching technology,explores the leaching behavior and kinetic mechanism of chalcopyrite under oxygen pressure water leaching conditions,and examines the influence of impurity minerals on chalcopyrite leaching,aiming to provide theoretical and data support for the development of chalcopyrite hydrometallurgy technology.In this thesis,the pure mineral of chalcopyrite was taken as the main research object.Firstly,the leaching behavior of chalcopyrite under oxygen pressure water leaching was investigated.The effects of particle size,temperature,oxygen partial pressure and stirring rate on the leaching of chalcopyrite were investigated,and the leaching residue was analyzed.The leaching process was fitted by surface chemical reaction model and product layer diffusion model,and the leaching kinetics of chalcopyrite was studied.Secondly,the leaching behavior of pyrite under oxygen pressure water leaching conditions was studied,and the leaching residues obtained under different conditions were analyzed.Finally,the effects of pyrite and quartz on chalcopyrite leaching were studied.The main conclusions are as follows:（1）The optimum conditions of oxygen pressure water leaching of chalcopyrite were obtained.The oxygen pressure water leaching test of chalcopyrite shows that the increase of temperature,oxygen partial pressure and stirring rate is beneficial to the leaching of copper.The order of influence is temperature>oxygen partial pressure>stirring rate,and the increase of particle size will hinder the leaching of copper.The optimum conditions were as follows:particle size of-47μm,temperature of 180°C,oxygen partial pressure of 1.2 MPa,stirring rate of 900 rpm and leaching time of 90min.Under these conditions,the copper leaching rate can reach 96%.At the same time,the highest iron leaching rate in all experiments was only 8%,and the separation of copper and iron was preliminarily realized.（2）The kinetic properties and transformation mechanism of oxygen pressure water leaching of chalcopyrite were revealed.The leaching kinetics study showed that the leaching process of chalcopyrite was controlled by surface chemical reaction,and the apparent activation energy was 62.34 k J/mol.The phase analysis of the leaching residue shows that the main component of the passivation layer produced during the chalcopyrite leaching process under the condition of oxygen pressure water leaching is Fe₂O₃,which also contains a small amount of Cu_1-xFe_1-yS_2-z;some covellite and pyrite were found during the leaching process,indicating that some chalcopyrite may not be leached directly,but undergo phase transformation and eventually enter the solution.（3）The difficult leaching mechanism of oxygen pressure water leaching of pyrite was found.The oxygen pressure water leaching test of pyrite shows that particle size,leaching temperature,oxygen partial pressure and agitation rate are important factors affecting pyrite leaching.During the leaching process,a large amount of Fe₂O₃ and elemental S passivation layer were produced,which made the iron leaching rate up to about 48%.（4）The influence mechanism of pyrite and quartz on oxygen pressure water leaching of chalcopyrite was revealed.Tests on the effects of pyrite and quartz on chalcopyrite leaching show that both can promote chalcopyrite leaching under certain particle size and content constraints.When the particle size of pyrite and quartz is-47μm and the content ratio of pyrite and quartz to chalcopyrite is 1:9,the leaching of copper in chalcopyrite can be promoted.This is related to the dissolution of pyrite to generate a certain amount of sulfuric acid and quartz can be attached to the Fe₂O₃passivation layer produced during chalcopyrite leaching.After exceeding the above limit,it may inhibit the leaching of chalcopyrite copper.