Behavior Of Al ₂ O During Carburizing Reduction Under High Temperature Vacuum

Research on gas products from carbothermic reduction process of alumina mainly concentrated on thermodynamics research and experimental research. Due to the limitation of low pressure and continuous reaction experiment equipment in high temperature,experiments are difficult to operate and the experimental results are not reliable enough. These basic researchs are insufficient to explain the complex reaction of carbothermic reduction process.By using ther mo dynamic calculation software, the Gibbs free energies with temperature changes under different pressures of the main reactions which may occur during the process of aluminum carbothermic reduction process have been acquired by thermodynamics calculations.Then theoretical calculations about reactions related to Al2O during the carbon thermal reduction process which based on density functional theory and ab initio molecular dynamics simulations method was carried on by using quantum mechanics calculation software. Theoretical research carried on from the reactions as follows:the formation of Al2O, the reaation of Al2O and C or CO to Al4C3,Al4CO4, the disproportionation of Al2O. By the thermodynarmc calculation about reactions during carbon thermal reduction process,9 main reactions related to Al2O was obtained.Thermodynamic study shows that aluminum generated in the condensation area, accompanied with the generation of Al2O3、C、Al4CO4、Al4C3、CO2(g) and other substance.The reactions not only reduce the recovery rate of Alumina,.but also affect the purity of aluminum. In the aspects of ab initio molecular dynamics simulation, the reaction of Al2O3 and C to Al2O in the carbon reduction zone was mainly simulated. The reactions of Al2O and C, CO (according to 1:1,1:4 two ratios) respectively, and the nucleation process of Al2O disambiguation reaction was carried out ab initio molecular dynamics simulation calculations. The results of this calculation shows that, the most likely reaction to occur in the condensation zone is Al2O disproportionation reaction to produce Al and Al2O3. Al2O and CO were more prone to react on C (001) plane,rather than Al2O3(001) plane and Al4CO4(001) plane.Reaserch on reactions of Al2O and CO of different proportion shows that Al4CO4 is more easily to obtained by the reaction of Al2O and CO.