Concept of EAF dust treatment using waste plastics containing brominated flame retardants

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. Due to the presence of significant amounts of leachable heavy metals, EAF dusts (EAFD) are classified as hazardous wastes. On the other hand the EAF dust contains up to 35 % of Zn, and is considered to be a valuable secondary raw material in the production of zinc. Numerous zinc recovery processes have been developed, many of them, however, were not commercialized because of metallurgical and economical inefficiencies. Few pyrometallurgical processes like Waelz rotary kiln process have achieved commercial success. Its main disadvantage, however, is high energy consumption (Waelz process requires temperatures of 1200-1300 °C). We proposed another alternative method for pyrometallurgical recycling of EAF dust using plastic waste containing BFRs such as TBBPA. It easily decomposes during thermal processing generating large amounts of gaseous HBr that can acts as a brominating agent for the bromination-evaporation of zinc and lead present in the dust. A new concept of EAF dust treatment process is proposed using waste plastics containing BFRs and merits and demerits are discussed with a review of EAF dust treatments in the present paper.