Exergy Efficiency and Energy Analysis of Silicon Production Using Coffee Husks as a Carbon Material

The silicon industry faces new challenges to increase sustainability and competitiveness as it is an energy-intensive sector with high energy running costs.The mixture of different carbon materials plays a very important role in the unit power consumption and exergy efficiency of the silicon production process. As an ideal reducing agent for industrial silicon, the demand for charcoal is increasing, posing a serious threat to the ecological environment. It is therefore urgent to study carbon-reducing agents which can replace charcoal, or to find energy-saving and cost-saving strategies for silicon production.In this study, we used waste biomass (coffee husks) as an additive during the smelting of industrial silicon. The influence of different carbon material mixtures on the silicon furnace performance was evaluated using the cover fire data, carbon excess factor, and exergy efficiency evaluation index. Explore its possibility as a reducing agent for silicon smelting.The results showed that TG increased by 47.75% on average after adding coffee husks. When semi-coke was used in the silicon furnace, the carbon excess factor was 1.29, the non-recovery exergy efficiency was 0.342, and the recovery exergy efficiency was 0.435. After adding coffee husks, the carbon excess factor decreased to 1.28, and the exergy efficiency increased to 0.343 and 0.437. When coffee husks were used without semi-coke, the carbon excess factor was reduced to 1.25, and the exergy efficiency increased to 0.348 and 0.441. The results indicate that using coffee husks as a reducing agent stabilizes the furnace conditions, reduces carbon loss, and improves the exergy efficiency of the silicon furnace. This study provides new insights into using raw biomass materials as reducing agents for silicon smelting.