Numerical Simulation And Experimental Study On The Temperature Field Of Vacuum Carbothermic Reduction Of Gallium Oxide

Gallium is an important rare metal and is widely used in the development of strategic emerging industries in China.Gallium is mostly extracted from metallurgical by-products,and the secondary resource containing gallium has become an important resource for comprehensive utilization of metallurgy.Using vacuum technology to process gallium-containing secondary resources to recover metal gallium has become one of the current research hotspots.Therefore,it is particularly important to carry out basic theoretical research on the comprehensive recovery of gallium metal from gallium-containing secondary resources.Gallium metal exists in the form of gallium oxide in gallium-containing secondary resources such as yellow phosphorus dust,and the vacuum carbon thermal reduction process makes it difficult to implement online temperature monitoring under experimental conditions due to its high temperature and low pressure environment.The finite element analysis method is used to calculate the temperature field of gallium oxide vacuum carbon thermal reduction,which provides theoretical guidance for studying the mechanism of temperature field change in the process of vacuum treatment of gallium-containing secondary resources.This paper first analyzes the feasibility of thermal reduction of gallium oxide under vacuum and high temperature.The calculation results show that compared with normal pressure,gallium oxide reacts preferentially with carbon to generate gallium and CO under vacuum and high temperature.Vacuum carbothermal reduction has obvious The?G_T value of the reduction reaction decreases with the increase of the vacuum degree(the pressure decreases)or the reduction of the reduction temperature,the stability of the gallium oxide decreases,and the reduction reaction proceeds more easily.Secondly,by establishing a numerical simulation model of the vacuum furnace and the condensing pan,the finite element analysis of the temperature field of the gallium oxide vacuum carbothermal reduction process was performed.The simulation results show that the heat transferred by the radiation in the reduction process increases the temperature of the reduction zone,and the temperature in the middle and lower part of the crucible(charging zone)quickly rises to 2500K and then starts to stabilize.Use principles.The closer the condensation zone is to the crucible opening,the faster the rate of temperature rise due to the greater amount of heat transferred by the radiation.The heating curve of the condensation zone is gentle and the temperature change mechanism is relatively consistent.During the condensation process,the temperature gradient in the condensate pan is reduced from 44K/cm to 24K/cm,the maximum temperature difference is reduced from 832K to 429K,the maximum temperature in the condensate tank is reduced from 928K to 763K,and the temperature of the center of the condensate tank is quickly reduced to 625K and remains stable.Choosing a crucible with excellent heat transfer performance and improving the performance of the heat shield in the furnace and optimizing the structure of the water cooling system will increase the maximum temperature difference between the two areas and reduce the temperature of the center of the condensation tank,which will be beneficial to the condensation and enrichment of the reduced products.Finally,under the guidance of the numerical simulation theory of the temperature field of gallium oxide vacuum carbon thermal reduction,an experimental study was conducted to verify the influencing factors of gallium oxide carbon thermal reduction.The experimental results show that:when the system vacuum degree is 1?10 Pa and the heating rate is 14K/min Under the best experimental conditions of reduction temperature of 1323K,holding time of 150min,and C/Ga₂O₃(molar ratio)of 4,the condensate is enriched on the condensation cover in the form of uniform particles,the reduction rate of Ga₂O₃ is 68.19%,and the reduction product condenses and recovers yield is 59.37%.Under this condition,the condensate phase is metal gallium and a small amount of gallium oxide generated by the disproportionation reaction.Gallium is fully enriched during the condensation process and is well separated from gallium oxide,which is beneficial to the recovery of gallium.The verification experimental results provide theoretical guidance for vacuum carbothermal extraction of gallium from gallium-containing secondary resources such as yellow phosphorus dust.