Thermodynamic assessment of aluminium production through carbosulphidation route

Indirect carbothermal reduction of alumina for the production of aluminium has been claimed to be better compared to the existing Hall-Heroult process in-terms of energy usage, generation of perfluorocarbons and overall greenhouse gas emission. In the process, alumina is reduced to an intermediate compound which is then further reduced to Al. It has been shown from the previous thermodynamic study by the authors that high conversion of alumina can be obtained if it is reduced to Al-chloride, Al-nitride or Al-sulphide. This paper deals with detailed systematic thermodynamic analysis of the process through carbosulphidation route, where alumina is first reduced to Al₂S₃ in the presence of reductant and sulphur source. Various ratios of carbon to sulphur have been considered in this modelling study. In the second stage, Aluminium is extracted from the Al₂S₃ through thermal decomposition, disproportionation or electrolysis. The different thermodynamic and energy analysis of the second stage is also discussed in this paper.