Investigation into the Hot Briquetting of Fine‐Grained Residual Materials from Iron and Steel Production

Abstract

Hot briquetting tests with mixtures of direct reduced iron (DRI) pellets and residues of the Midrex direct reduction process are conducted on a hydraulic piston press with a closed die. The trials seek to test the feasibility of recycling these residues by introducing them directly into hot briquetted iron (HBI). The inclusion of residues is possible if a high pressure of 350 MPa and a high briquetting temperature of 800 °C are applied. It is ascertained that up to 20 wt% of the HBI can consist of residues and still meet the quality requirements for the safe transportation to the steel plant if the mixture contains sufficient HBI screened fines and HBI classifier dust. Under such conditions, the HBI briquettes have a compressive strength of >300 MPa, an abrasion resistance of >80%, and, most importantly, an apparent density of >5 g cm−3. It is further shown that the hot briquetting of Midrex residues is also possible without DRI pellets so that they can be reused as educt in the Midrex direct reduction process.