Thermodynamics on formation of C, Al4C3 and Al2O3 in AlCl disproportionation process in vacuum to produce aluminum

The formation conditions of C, Al4C3 and Al2O3 in the AlCl disproportionation process in vacuum to produce aluminum was investigated by thermodynamics analysis. It is demonstrated that the required temperatures for the reactions to form these impurities, the disproportionation of CO and the reactions of metallic aluminum with CO, decrease with decreasing pressure. The lg pCO–1/T diagram of metallic aluminum–CO system agrees with the experimental results, indicating that the reaction rate is very high and this system in vacuum is approximately in equilibrium; therefore, the equilibrium diagram can be used to predict the possible reactions in this system in vacuum.