Abstract
In this paper, experimental investigation on the carbosulphidation of alumina (Al
2
O
3
) for aluminium (Al) production and the sodiothermic reduction of aluminium sulphide (Al
2
S
3
) are presented. Hydrogen sulphide (H
2
S) was used as a reductant and source of sulphur. This work is the second of two-parts paper series. The experimental investigations of the Stage-1 process (Al
2
O
3
carbosulphidation) were carried out at 1100-1600°C using a laboratory scale horizontal tube resistance-furnace. H
2
S gas, diluted with argon (5% H
2
S and 95% Ar), was reacted with pellets of a mixture of γ-Al
2
O
3
and C powders (1:6 molar ratio) to produce Al
2
S
3
. The effects of gas injection rate, pelletizing pressure, temperature and reaction time on the conversion of Al
2
O
3
to Al
2
S
3
were investigated. The X-ray diffraction results confirmed the formation of Al
2
S
3
(s) in the reaction product above 1400°C. The conversion of Al
2
O
3
to Al2S3 was found to be 99.5% at 1600°C and 12 h. The kinetics analysis of alumina sulphidation using Ginstling-Brounshtein diffusion model suggested the overall reaction was controlled by the diffusion of H
2
S gas through the reaction product (liquid Al
2
S
3
). The activation energy of the alumina sulphidation reaction was calculated to be 148.5 kJ mol
−1
. It has also been demonstrated in this study that Al can be extracted from Al
2
S
3
by sodiothermic reduction using Na or NaH. In the case of Na, a level of Al conversion of 75% has been observed for reaction at 290°C.