Influence of carbon material on the production process of different electric arc furnaces

The characteristics and applications of carbonaceous materials play a vital role in silicon production using an electric arc furnace, as this is an energy-intensive industry with high energy operating costs that is currently facing severe challenges to become more sustainable and more competitive. In this study, the effect of different carbon materials on specific electrical consumption and the exergetic efficiency and the silicon yield for two types of furnace was investigated using a statistical analysis method based on actual production data from the silicon plant. The highest exergetic efficiency values of 0.39 (8.3 MVA) and 0.42 (12.5 MVA) without recovery were obtained by the application of petcoke and charcoal. The exergetic efficiency was higher in the larger capacity furnace than in the smaller furnace for the same consumption of raw materials. The correlation between exergetic efficiency and carbon materials was evaluated and revealed that the moisture content and graphitization of raw materials have a significant effect on the exergetic efficiency. The reactivity of mixtures was improved by synergistic interactions between petcoke and coal or woodchips, which increased the carbothermic reduction utilization of silica based on the higher silicon yield indicator, but reduced the exergetic efficiency and silicon actual production, as it increased the specific electrical consumption.