Pyrometallurgical recycling of EAF dust using plastic waste containing TBBPA

Tetrabromobisphenol A (TBBPA) is the largest volume brominated flame retardant (BFR) in production today, used in more than 70 % of the world's electronic and electric (E&E) appliances as well as in many plastics, textiles and so forth. There is constant growth in the production of such products and they become obsolete quickly, this generates huge amounts of BFR-containing wastes and causes significant problems for their safe disposal and recycling. The most common way to treat them is thermal processing. TBBPA easily decomposes during this process, generating significant amounts of gaseous HBr. The HBr is present mostly in the flue gas and can act as a bromination agent for selective bromination-evaporation of heavy metals present in co-combusted metallurgical dusts, like zinc and lead-rich electric arc furnace (EAF) dust. EAF dust, though classified by various government regulatory agencies as hazardous waste, is considered a valuable secondary raw material in the production of zinc. The worldwide generation of EAF dust represents a possible recovery of approximately 1.4 million tons of zinc. Thus the cocombustion of the mixed wastes can be a opportunity for simultaneous recovery of both, energy from waste plastics and inorganic fractions from the dust, while the separated iron oxide-rich residues can be used as iron-making and steel-making resources. In this study, a laboratory-scale furnace was used to investigate (1) the reactivity of zinc with the product of the thermal decomposition of TBBPA, and effect of (2) temperature on the efficiency of the bromination and vaporization processes.