Interactions between blends of metallurgical coke and polymers with EAF slag (30.5% FeO) at 1 550°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.

Recycling end of life products, such as waste tires and waste plastics in iron- and steelmaking permits their use as energy and material resources. The current paper discusses the combustion efficiencies of blends of metallurgical coke (MC) with plastics for electric arc furnace (EAF) steelmaking. Laboratory tests involved the combustion in a drop tube furnace (DTF) at 1473 K of MC premixed with different proportions of plastics, polypropylene (PP), and high-density polyethylene (HDPE) (10−30%) under a 20% O2 and 80% N2 gas mixture. In the tested conditions, coke−plastic blends indicated higher combustion efficiencies compared to coke. The gas-phase reactions appear to be influenced by the amount of volatile matter present in the carbonaceous matrix and its subsequent effect on the structural transformation of the particles because of the release of volatiles. The surface area of the coke−polymeric mixtures before and after combustion was found to be higher than the surface area of coke alone. The residual chars collected after the reaction in the DTF were characterized as a function of pore volumes and surface area of the particles. A previous study has demonstrated the possibility of partially replacing conventional coke in EAF steelmaking with end of life rubber tires. The present paper studies the potential replacement of MC with waste materials, such as PP and HDPE, as auxiliary fuels in EAF steelmaking. A comparison to previously reported combustion efficiencies for rubber blends is also provided.

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Bakelite is a thermoset plastic commonly found in electronic and automobile components. CaCO 3 is generally found in the polymer as a filler material. Since it cannot be remelted, the disposal of this material has become an environmental issue. The present study investigates a new route to utilize waste bakelite as a source of carbon in EAF steelmaking process. This paper reports the carbon dissolution behaviour of bakelite/ coke blends into liquid steel at 1550 8C. The carbon pick up in the liquid steel after reaction with varying blends of bakelite/coke for 30 minutes ranged between 0.13 wt% to 0.17 wt%; these were generally higher than that observed from coke alone (0.1 wt%). The dissolution rate (K) was also found to improve and the observed trend was BK2 (0.045 Â 10 À3 s À1 ) > BK3 (0.023 Â 10 À3 s À1 ) > BK1 (0.005 Â 10 À3 s À1 ) > coke (0.003 Â 10 À3 s À1 ). The reaction products formed at the interface after 30 minutes of contact between liquid steel and bakelite/coke blends were observed to be a CaS-Al 2 O 3 complex. The presence of CaS in the interfacial layer due to the CaO in the ash, lowered melting temperature of the layer, thereby allowing for increased removal of the ash layer and greater carbon pick-up. The CaO is formed from the decomposition of CaCO 3, and its presence was found to have a positive effect on modifying the properties of the coke, and thereby enhancing the carbon dissolution behaviour.