Development of carbon composite iron ore micropellets by using the microfines of iron ore and carbon-bearing materials in iron making

Abstract

Iron ore microfines and concentrate have very limited uses in sintering processes. They are used in pelletization; however, this process is cost intensive. Furthermore, the microfines of non-coking coal and other carbon-bearing materials, e.g., blast-furnace flue dust(BFD) and coke fines, are not used extensively in the metallurgical industry because of operational difficulties and handling problems. In the present work, to utilize these microfines, coal composite iron oxide micropellets (2–6 mm in size) were produced through an innovative technique in which lime and molasses were used as binding materials in the micropellets. The micropellets were subsequently treated with CO2 or the industrial waste gas to induce the chemical bond formation. The results show that, at a very high carbon level of 22wt% (38wt%coal), the cold crushing strength and abrasion index of the micropellets are 2.5–3 kg/cm2 and 5wt%–9wt%, respectively; these values indicate that the pellets are suitable for cold handling. The developed micropellets have strong potential as a heat source in smelting reduction in ironmaking and sintering to reduce coke breeze. The micropellets produced with BFD and coke fines (8wt%–12wt%) were used in iron ore sintering and were observed to reduce the coke breeze consumption by 3%–4%. The quality of the produced sinter was at par with that of the conventional blast-furnace sinter.