Recycling Waste Polymers in EAF Steelmaking: Influence of Polymer Composition on Carbon/Slag Interactions

Abstract

Interactions between blends of metallurgical coke and polymers with EAF slag (30.5% FeO) at 1550°C have been investigated using a sessile drop arrangement to determine the influence the polymer and its chemical composition on carbon/slag interactions. Two polymers, namely polyethylene terephthalate (PET) and polyurethane (PU), were used in this study. The CO emissions during carbon/slag interactions for PET/Coke and PU/Coke blends were lower as compared to corresponding emissions from metallurgical coke. An improvement in slag foaming, as determined by the dynamic changes in the volume of the slag droplet, was observed when PET/Coke and PU/Coke blends were used compared to the coke alone. Relatively greater number of gas bubbles was found to be entrapped in the slag droplet along with reduced iron droplets. Higher level of H₂O formation was also seen in the case of PET/Coke and PU/Coke blends as a result of FeO reduction by H₂. These results indicate that volatiles (H₂ and CH₄) released from the polymer/coke blends can influence the interactions between carbon and slag (in addition to reduction reactions by solid carbon). This study shows that a variety of waste polymers can be utilised as a carbon resource in EAF steelmaking processes.