Study On Comprehensive Recovery Of Metal Component In Red Mud From Bayer Process By Acid Leaching And Sedimentation Flotation

With the rapid development of Chinese alumina industry,a large amount of red mud solid waste that urgently needs to be disposed of has been generated during the alumina production process.Red mud has the characteristics of high alkalinity,fine particle size,and complex composition,making comprehensive utilization difficult.At present,red mud is mainly stored in the open air,which not only has a huge impact on the environment,but also caused a huge waste of resources.Red mud contains a large amount of valuable metals such as titanium,iron,aluminum,etc.It is of great significance to carry out research on efficient separation and recovery technology of metal components in red mud.In this study,the acid leaching-precipitation flotation-hydrolysis method was used to separate and recover the three metal elements of titanium,iron and aluminum in the red mud.Through single-factor experiments,combined with analysis and simulation methods such as FTIR,ICP-AES,SEM,and Visual MINTEQ,to explore the mechanism of the leaching process and flotation process of Ti、Fe、Al.The main findings of this paper are as follows:（1）The technological mineralogical study of red mud showed that the TiO₂content in the red mud sample used in the experiment was 4.52%,the Fe₂O₃ content was 20.56%,and the Al₂O₃ content was 19.44%.The iron in the red mud mainly exists in the form of hematite（Fe₂O₃）,the aluminum mainly exists in the form of cancrinite(Na₆(Al₆Si₆O₂₄)（Ca CO₃）（H₂O）₂);the titanium mainly exists in the form of rutile（TiO₂）;Silicon and calcium mainly exist in the form of calcite（Ca CO₃）and quartz（Si O₂）.（2）The research on the acid leaching process of titanium iron aluminum in red mud shows that the optimized red mud acid leaching process conditions are:reaction temperature of 90℃,reaction time of 150 min,sulfuric acid concentration of 3 mol/L,and liquid-solid ratio of 10:1,The stirring speed is 300 rpm.Under this leaching process,the leaching rates of titanium,iron and aluminum in the red mud are 75.96%,64.99%,and 92.55%,respectively.The study on the leaching kinetics of titanium,iron and aluminum shows that the apparent activation energy of the leaching process of titanium and iron is 49.84 k J/mol and 45.64 k J/mol,which are in line with the chemical reaction control model;the apparent activation energy of the leaching process of aluminum is 4.049 k J/mol,in line with the diffusion control model.（3）Study on the behavior and mechanism of simultaneous separation of titanium-iron-aluminum chelation-precipitation flotation in acid leaching solution shows that the optimized chelation reaction conditions are N-nitrosophenylhydrazine as the metal ion chelating agent,and the chelating agent is added The amount is 14 mmol/L,the reaction time is 30 min,the reaction temperature is 30°C,the pH of the solution is 1,the chelation rate of ferro-titanium is 99.98%and 99.79%,respectively,and the chelation precipitation rate of aluminum is only 5.62%.With CTAB as the surfactant,the pH of the solution is 1.0,the dosage of CTAB is 1.5 mg/L,the flotation removal rates of titanium and iron are 99.89%and 99.96%,and the flotation removal rate of aluminum is only 3.43%.Efficient separation of titanium and aluminum.The investigation of the mechanism of the chelation process shows that:（a）The surface of the chelated precipitation particles is negatively charged.As the pH of the solution increases,the electronegativity of the surface of the precipitated particles increases,making it difficult for fine particles to overcome the electrostatic repulsion between the particles and further form large sizes.Chelating precipitation aggregates;（b）When the dosage of chelating agent is less than the optimal value,it is easier to form large-sized particles when the dosage is increased.When it exceeds the appropriate value,continue to add more chelating agent and the particle size becomes smaller.（4）The research on ferro-titanium flotation product reduction-hydrolysis separation of ferro-titanium shows that:KI is used as the reducing agent of Fe（III）ions in ferro-titanium solution,the pH of the solution is 3,the reaction temperature is 20℃,the reaction time is 1 h,and the reduction When the ratio of agent KI to Fe（III）is 1.5:1,the precipitation rate of titanium is 99.82%,the precipitation rate of iron is only 6.83%,and the separation effect of titanium and iron is good.The final calculation shows that the recovery rates of titanium and iron in the red mud are 73.49%and 62.46%,respectively.