Study On The Migration Behavior Of Impurity Elements In The Process Of Purifying Aluminum By Zone Smelting

As an important metal material,high-purity aluminum has been widely disseminated in emerging fields such as electronic information,aerospace,and precision instruments.High purity Al is an important metal material,which have been widely used in high-tech fields such as electronic information,aerospace and precision instruments.The traditional three-layer liquid electrolysis method for preparing high-purity Al have problems such as non-environmental protection,and long process flow.The traditional three-layer liquid electrolysis,segregation method and other processes for preparing high-purity aluminum have problems such as high energy consumption,non-environmental protection,and long process flow,which restrict the development of the high-purity aluminum industry to a high-precision direction.It restricted the development of the high-purity Al industry to a high-precision direction.The zone smelting is an important method for clean metal purification using this purification process to study the migration and distribution of impurity elements can guide the determination of purification parameters,so as to achieve good purification results.In this method,studying the migration and distribution of impurity elements can guide the determination of purification parameters,thereby affecting the purification effect.Most research focuses on the optimization of purification parameters and related simulations.However,it is rare to study the migration law of impurity elements in Al to guide the determination of the optimal purification parameters.The current research about this method focuses on the optimization of purification parameters and related numerical simulations,and seldom pays much attention to the migration law of impurity elements in aluminum to guide the determination of the optimal purification parameters.In this paper,zone smelting method was performed to prepare high-purity aluminum,by using a combination of simulation calculation and experiment to study the migration behavior and removal effect of impurity elements in aluminum,in order to clarify the migration and distribution of impurity elements in aluminum between solid and liquid phase,and obtain the impurity removal control mechanism enriches the basic theoretical data for the preparation of high-purity aluminum by the zone melting method,and provides certain theoretical support and experimental data for the technical development and application of the preparation of high-purity aluminum by the zone melting method.The main progress achieved was as follows:The main progress achieved was as follows:Based on the crystallization theory,the impurity distribution behavior in the aluminum zone smelting process is theoretically analyzed,which shows that there is a phenomenon of crystallization during this process,that is,the impurity elements Si,Fe,Cu,Zn,etc.(k₀<1)are crystallized out Under the action,it will migrate to the end of the aluminum ingot along the moving direction of the molten zone.COMSOL Multiphysics 5.3a software was used to carry out simulation study of the temperature field in the melting zone during the purification process.The results show that changes in parameters such as the structure of the graphite crucible,the position of the heating coil and the number of turns of the coil canaffect the distribution of the temperature field in the melting zone.Based on the calculation results of the molten zone moving mesh format modeling method,the best parameters for the stable temperature field are:coil width was 1.0 cm,the heating voltage was 1.165 k V,the melting zone temperature was 663?,and graphite crucible cross section is rectangular.The acquisition of the above parameters provides theoretical supported for the accurate setting of the parameters in the actual heating process.The effect of different parameters on the actual effective distribution coefficient(k_e)was explored.The results show that the moving speed of the molten zone and the number of purifications are the main factors affecting the ke of impurities such as Si,Fe,Cu,and Zn.The experimental results of purifying high-purity aluminum under argon atmosphere show that the moving speed of the molten zone is 0.5 mm/min,and the impurities Cu,Fe,Si and Zn in the middle position of the aluminum ingot sample(No.3)are removed when the melting zone is purified for 15 times.The rates reached 94.54%,98.61%,76%and78.16%,respectively.The degree of influence on the impurity removal rate is Fe>Cu>Zn>Si,the aluminum content is 5N1,and the sample composition meets the 5N aluminum standard.The relationship between the purity of Al and its morphology was studied,that was,the higher the purity,the larger the particle size.At the same time,it was found that due to the presence of argon gas flow and trace oxides,oxide films and wrinkles appeared on the surface of the sample.The relationship between the purity of aluminum and its morphology was studied,and the relationship between purity and grain size was obtained by fitting.The purification experiment results under vacuum conditions showed that the removal rate of impurity elements Si,Cu,Fe and Zn were 92.47%,97.96%,99.59%and77.5%when the molten zone moving speed was 0.5 mm/min for 15 times.The removal effect is Fe>Cu>Si>Zn,the aluminum content in the middle position(No.3)is 5N6,and the content of various impurities meets the 5N aluminum standard.Compared with normal pressure conditions,the oxidation degree and wrinkle effect of the sample surface are significantly weakened,and the removal rate of impurity elements is higher.At the same time,it was found that due to the higher purity of aluminum in the sample,the size of the crystal grains formed increased significantly.Through the simulation of the zone melting temperature field and the calculation of the actual effective distribution coefficient of impurities,purification experiments under different conditions have been carried out,and the technical plan for zone melting purification of aluminum has been further established,so that the purity of 4N primary aluminum can be purified.Both the purity and the content of impurity elements meet the requirements of the 5N high-purity aluminum standard.At the same time,the sample has larger grain morphology,achieving the expected purification effect.This subject has thoroughly and systematically studied the scientific issues in the process of regional smelting and purification of aluminum,which is of great significance for the development of green preparation of high-purity aluminum technology.