Microwave selective heating of electric arc furnace dust constituents toward sustainable recycling: Contribution of electric and magnetic fields

Microwave heating of waste electric arc furnace dust (EAFD) for the purpose of its remediation has been studied extensively. However, these studies considered EAFD as a bulk material without addressing either the relative response of its individual constituents or the specific interactions with either the electric or magnetic fields of an electromagnetic wave. In this work, we present a study of the relative contribution of the electromagnetic wave components to the heating of EAFD constituents using separated electric and magnetic microwave fields. ZnO, ZnFe2O4, Fe3O4, and graphite were found to be the main contributors to the heating of EAFD based on their dielectric properties and heating profiles. ZnO and ZnFe2O4 heated only in the electric field yielding temperatures of 846 and 720 °C after heating for 30 and 40 s, respectively at a power input of 118 ± 12 W. Fe3O4 and graphite, in contrast, heated in both electric and magnetic fields owing to their respective magnetic and conductive nature. It is suggested that the selective magnetic heating of Fe3O4 has significant implications for the selective extraction of zinc and lead through thermal treatment of EAFD with halogenated plastics such as polyvinyl chloride (PVC).