Carbothermic Reduction of Bauxite and Colloidal Earth by Girod and Héroult Furnaces (Studies on the Production of Crude Aluminum Alloy by the Direct Reduction of Aluminous Ores (V))

Abstract

As a part of the study relating to direct reduction of aluminum, the preparation of aluminum alloy was carried out by means of the 10 kVA Girod and the 70 kVA Héroult furnace using bauxite and colloidal earth, and the reduction process and operational conditions were clarified.
During the preliminary treatment of the source materials, it became clear that briquetting and pelletizing were more effective to make the reduction easier and to obtain a more uniform tapped alloy than in the case of the separate charge of bauxite and colloidal earth. In addition, a larger amount of the alloy with a higher aluminum content in the tapped metal was obtained from the mixture.
The differences in the carbonaceous materials among charcoal, coal and cokes were not made clear. The alloy contained 32∼55% Al, 20∼54% Si, 15∼32% Fe, and 2∼4% Ti. The reduction ratios of Al₂O₃ and SiO₂, were of the same level, while Fe₂O₃ was about twice greater than them. Chemical and X-ray analysis of the residual matter showed that the alloy was formed mainly between aluminum oxide and silicon carbide.