Conversion of Sponge Iron From Low Grade Iron ore And Mill Scale Through Simulating Tunnel Kiln Condition

The present investigation deals with the feasibility study of the process development for production of Directly Reduced Iron (DRI) using waste/low grade iron ore (slime), mill scale and waste/less reactive coal (partly oxidized coal i.e. Jhama coal). In order to get most green and dry strength for safe handling and transportation, the pellets of iron ore slime and the pellets of mill scale were made in disc pelletizer with optimum moisture. Dried iron ore slime pellets reduced the bed of Jhama coal fines at different temperature and sintering time. Detailed investigation for the reduction kinetics of slime pellets with Jhama coal has been carried out to explore the feasibility of slime pellets reduction. Based on reduction kinetics, process criterion for reduction of pellets with Jhama coal is optimized to produce highly metallic DRI. The Reduction of dried pellets was carried out without in duration/firing higher temperature as compared to the conventional DRI process yielding high energy efficient and cost-effective process. An optimized work flow sheet and innovative process has been developed for production of high quality DRI utilizing waste iron ore slime and less reactive coal (Jhama coal). The DRI produced from this process have high metallization (<92%) suitable for blast furnace and electrical for iron and steel making. I. Introduction Mill scale is an iron oxide waste generated during steelmaking process, casting and rolling. The mill scale contains very high percentage of iron which is generated during making of steel towards production of various long and flat products. The major part of mill scale in an integrated steel plant is recycled for in house consumption; but no commercial process for its utilization is so far available for the secondary sector in industries. So it is either dumped or exported at a very low price. It is appeared on the outer surfaces of plates, sheets or profiles when they are being produced by rolling red hot iron or steel billet in rolling mills. It is composed of iron oxides mostly ferric and is bluish black in color. It is regularly less than 0.1 mm (0.0039 in) thick and initially adheres to the steel surface and protects it from atmospheric corrosion contributed no break occurs in this coating. Here some preliminary results of a laboratory scale investigation has been done which involves pelletization of mill scale, using steel plant waste as an additive and following reduction of the air dried pellet by non-cooking coal fines under conditions, simulating a tunnel kiln. The results of this investigation indicate that the green pellets could be successfully handled, without generating much of fines and could be change to highly metalized Directly Reduced Iron (DRI) at a moderate temperature and at a reasonably low heating time.Mill scale, a high iron containing body was thus used as a waste for a long time and was dumped. However, in recent past a convincing part of mill scale is being exported to China at a very low price. Though a small amount of mill scale is utilised in ferroalloys, cement and petrochemicals industry, there is a potential for production of almost 1.0 Mt of steel, alike with the current level of mill scale generation. All the above calls for an initiative to find satisfactory means for effective utilization of mill scale. The generation of steel and corresponding mill scale in India is given in figure 1.