Glass—Mill Scale—Plastics Wastes Upcycling for Synthesis of Ferrosilicon Alloy at 1550 °C: Implication for Zero Wastes Practice

Abstract

Driven by the rising demand for glass, metals, and plastics in industrial and household sectors, there was a substantial increase in waste and by-products generated. This study presents a method for repurposing waste glass, mill scale, and plastics as raw materials for ferrosilicon alloy production. This process entails reducing SiO2 and Fe2O3 using carbon derived from polystyrene/polypropylene mixtures. The glass, scale, and carbon powders were blended to achieve a C/O molar ratio of 1 (Blends A to F). The thoroughly mixed samples were then shaped into pellets and subsequently heated at 1550 °C in a tube furnace for 60 min. Ferrosilicon was successfully synthesized, with the reaction generating numerous metal droplets along with a slag layer in the crucible. The metallic yield for Blends A to F ranged from 16.65 wt% to 21.39 wt%, with the highest yield observed in Blend D. The bulk metal primarily consists of the FeSi phase, with Blend D exhibiting the highest Si concentration of 13.51 wt% and the highest hardness of 649.55 HV. Mechanism steps for ferrosilicon formation may vary with carbon dissolution rates. This work supports fossil fuel reduction and carbon neutrality, benefiting zero wastes practice and promoting sustainable material processing.