Cold Briquetting of DRI Fines for Use in Steel Making Process

Abstract

DRI fines, generated during its manufacture and handling, generate high content of fines in the size fraction less than 2 mm. It has iron content above 80%. It is difficult to directly use such iron-rich material in the primary steel making process, without agglomeration. At JSW Steel Vijayanagar, around 50 to 70 tons per day of DRI fines with < 2 mm size fraction get generated. The fines are used in base sinter mix or it may be agglomerated suitably to use it as a coolant in the primary steel making process. Since the fines are extremely reactive, they are susceptible to oxidation if it is not agglomerated as soon as it is generated. The present study brings out the development of an agglomeration process for the DRI fines to a dense metallized briquette, for use as a coolant in basic oxygen furnace. Initially, the conditions for briquetting such as use of binder, hardener, lime, dust, moisture, briquetting and curing conditions were established in a 10 kg batch size. This was followed by industrial-scale processing, at 500 kg batch size. The physical and chemical characteristics of the fines and briquettes were assessed at different stages. The cold compressive strength of the cured briquette was found to be a function of moisture content. The handling parameters in the production condition, for long-term pile-up of briquettes against oxidation, were brought out. The successful use of the briquettes in basic oxygen process was demonstrated.