Reduction Behaviour of Iron Ore Pellets

Demand of sponge iron and pre-reduced pellets for the manufacture of different varieties of steel is increasing day by day and new solid reductants based sponge iron plans are being commissioned. In the existing blast furnace an increase in production by at least 25 to 35% can be achieved by using pre reduced iron ore. Pre-reduced iron ore pellets have been established as a good substitute for steel scrap in an electric arc furnace which enhances the productivity of the arc furnace. A lot of investigations have been carried out on direct reduction process of iron oxides by carbonaceous materials, but little work has been done on the characterization of properties and reduction behavior of iron ore of. In the present project work, an attempt has been made to study the reduction behavior and kinetics of iron ore fired pellets. The effect of different reduction parameters such as temperature (850-1000ºC), time (15-120 minutes.), mixing of particles of different sizes at different ratios for pellet preparation etc. on the reduction behavior of iron ore pellets. These form the subject matter of the thesis. First chapter gives the introduction about the subject. It speaks about the need of DRI industry, scope, present status and future planning of DRI industry in India, world wise DRI production, etc. It gives a general idea of raw materials quality required for producing DRI, especially in Rotary Kiln. The second chapter deals with the literature survey. The third chapter deals with planning of experiments, selection of raw materials, preparation of samples, preparation of iron ore pellets, experimental procedure , evaluation of reduction and activation energies, etc. The results obtained and the discussions made from these observations have been outlined in chapter four. The result for fired iron ore pellets indicated an increase in degree of reduction with increase in reduction temperature (850-1000ºC) and time. The reduction kinetics of Zenith iron ore pellets were studied in temperature range of 850-1000ºC. The data were fitted on a differential model and the activation energies of reduction of pellets were calculated. Analysis of swelling behavior was also done. Results obtained from chapter four have been summarized in chapter five. Lastly, these conclusions have been followed by the list of references