Use of Biocarbon and its Agglomerates in Silicon and Ferrosilicon Production

This paper reviews the use of biocarbon as a renewable carbon source to reduce CO2 emissions in silicon and ferrosilicon production. Fundamental methodologies for characterizing biocarbon properties and their key findings are discussed and summarized. Charcoal, as a renewable reductant, has demonstrated promising potential to replace fossil carbon because of its thin cell walls and high porosity, which enhance its reactivity toward SiO gas. In addition, both charcoal and SiC-converted charcoals possess lower electrical conductivity compared with conventional carbon materials. However, a significant amount of fines is also generated during the processing and handling of biocarbon materials. The complete (100%) replacement of biocarbon still presents challenges for operations in the submerged arc furnace, as these fines reduce gas permeability and lead to uneven pressure distribution in the furnace. Rather than being discarded, these fines can be reused through densification methods that improve their mechanical strengths. In the production of charcoal agglomerates, selection of an appropriate binder is crucial. Therefore, the performance of charcoal briquettes produced with different types of binders is also reviewed. Improving the mechanical strength of charcoal briquettes/pellets, while achieving optimal mechanical strength and gas reactivity, is crucial for their effective use as biocarbon reductants in silicon and ferrosilicon production.