Microwave-assisted self-reduction of EAF dust-biochar composite briquettes for production of direct reduced iron

Abstract

This study applied microwave energy for rapid self-reduction of electric arc furnace (EAF) dust-biochar composite briquettes to produce powdered direct reduced iron (DRI), based on the good electromagnetic response of EAF dust-biochar composite briquettes. The reduction experimental results showed that the iron-bearing components in the dust were reduced to metallic iron, leading to a high iron metallization degree of the reduced briquettes (94.7%). Meanwhile, the zinc-containing phases of EAF dust in the composite briquettes were converted to metallic zinc which then volatilized together with lead in the form of PbCl2. The volatilization percentages of zinc and lead were 99.6% and 92.9%, respectively, after reduction with the mass ratio of biochar to EAF dust of 0.25 and heating rate of 25 °C/min at 1050 °C for 15 min. By magnetic separation of the reduced briquettes, a magnetic concentrate with iron content of 91.32 wt% and recovery of 87.36% was obtained, meeting the quality requirements of DRI.