Preheating of HBI for electric arc furnace steelmaking

The increasing use of Hot Briquetted Iron (HBI) as a feed stock to electric arc furnace (EAF) steelmaking presents significant challenges to producers in terms of energy usage and productivity. In this context, the University of Wollongong has been studying the use of the hot off gases from EAF's for the preheating of RBI feed to an EAF. Of particular concern is the potential for excessive oxidation of the HBI from the hot oxidised gases. A thermodynamic model was developed to predict what energy savings were available through preheating for different levels of post combustion, heat transfer efficiency and scrap/HBI feed ratios. The results from this model indicated that significant savings were achievable. A thermogravimetric study of HBI was carried out using a range of gases including N2, CO2, air, CO2/O2 and CO2/O2/N2 mixtures. The study identified that when HBI was heated in an oxidising atmosphere simultaneous oxidation and decarburisation reactions took place. These results indicated that oxidation of HBI during preheating should not be a significant problem