Transforming waste plastic into reductants for synthesis of ferrosilicon alloy

A novel process to transform waste plastic as a reducing agent and therefore as an alternative carbonaceous source in the production of silicon bearing alloys is investigated. Bakelite, a thermoset plastic that is difficult to recycle, is used in this study. Heat treatment of Bakelite was carried out at 1550 °C in argon atmosphere to investigate volatiles generation, presence of ash impurities, carbon structure, and properties as a result of transformations occurring during heat treatment. Simultaneous influence of these properties on ferrosilicon alloy synthesis is established. Initial volatiles generation from Bakelite accelerated the rate of silica reduction, particularly the formation of silicon carbide (SiC) through gas phase reduction reactions of silica. Calcium carbonate (CaCO3) impurity in Bakelite acts as a fluxing agent and facilitates the separation of metal alloy from slag. Bakelite derived carbon obtained during heat treatment showed enhanced crystallinity coupled with lower levels of porosity in structure with increasing time. Carbon obtained through transformation of Bakelite could serve as a reducing agent to produce ferrosilicon. This scientific study of using Bakelite as a reductant will create new opportunities to re-form waste plastics as raw materials in ferrosilicon alloy synthesis