Recycling

Biography

Biography: Ashraf Bakkar

Abstract

World production of steel is about 1.6 billion tons annually. About one third of this amount is produced in electric arc furnace (EAF), which evolves about 20 kg of dust per ton of steel. Thus, more than 10 millions of dust waste is formed annually during steelmaking in EAFs worldwide. Recycling of this dust in iron- or steel-making is hazardous and therefore it is mostly dumped. The dust is rich in Fe and Zn (from galvanized ferrous scraps charged to EAF). It contains also elements such as Pb, Cr, and Cd. These toxic elements led the EAF dust to be categorized as hazardous waste, where they leach in water and pollute groundwater. Such dust waste can be also resulted from other steelmaking processes in cupola furnace and other steel converters. In this contribution, we present our results of recent research on recycling of steelmaking dusts evolved from EAF, cupola furnace, and steel converter through selective dissolution of Zn and Pb in deep eutectic solvents composed of mixtures choline chloride with urea and/or ethylene glycol. About 60% of Zn and 40% of Pb found in EAF dust as complex compounds were selectively dissolved. The resultant electrolyte was then used to electrowin Zn-Pb alloys. Pure Zn, which has a very high economical value, can also be electrowon separately. The residual dust, after its extraction in deep eutectic solvents, with lower Zn and Pb and higher contents of Fe oxides can be recycled in steelmaking processes. Moreover, the lowering Zn and Pb contents make the residual dust to be suggested for in corporation in cement synthesis. This approach was also applied for treating dusts evolved from other steelmaking processes and showed promising results.