Abstract
In the industrial ferroalloy (FeMn/SiMn) and silicon (Si) production processes, carbon materials are used as the main reductants. Selection of the carbon materials have an effect on energy consumption, operational stability and ultimately the yield and quality of the final product. Substituting fossil carbon with biocarbon as reductants is a meant to reduce the CO2 footprint which is currently investigated in ferroalloy industry. Properties of various fossil reductants and charcoal and their impact on ferroalloy production have been investigated and are here compared. "Boudouard reaction" which is the CO2 reactivity of carbon results in an increase in the consumption of carbon and energy, thus knowledge about the reactivity of the chosen reductant and its impact is important. The reactivity is dependent on several factors including physical properties and chemical composition. Methods to study CO2 reactivity and results from investigations of various carbon materials are presented and discussed. Studies show that charcoal has highest CO2 reactivity due to its physical and chemical properties. High amount of fines inside the ferroalloy furnace will reduce the charge permeability and have a negative effect on furnace operation. Thermal strength of the carbon materials is thus an important property for its use. Methods to study thermal strength and fines generation and results from investigations of various carbon materials have also been investigated and are presented and discussed. The lower thermal strength of charcoal compared to traditional fossil carbon sources may limit its use. Methods to mitigate this as use in bio-coke is presented. Differences between carbon sources in density and content of volatiles are other parameters that are compared and discussed.