Sponge iron is also known as Direct Reduced Iron (DRI). Direct reduction, is an alternative route of iron making has been developed to overcome some of these difficulties of conventional blast furnaces. DRI is successfully manufactured through either gas or coal-based technology. Iron ore is reduced in solid state at 800-1050 c either by reducing gas (H2+CO) or coal. The specific investment and operating costs of direct reduction plants are low compared to integrated steel plants and are more suitable for many developing countries like where supplies of cooking coal are limited. The direct reduction process uses palletized iron or natural ‘lump’ ore.

Sponge iron making is a process in which iron ore lumps (typically 5mm-18mm size) are tumbled with a ‘select’ grade of iron-cooking coal little dolomite inside an inclined rotary kiln and control combusted in the presence of air for about 12 hours before the products are air cooled, magnetically separated, screened and size wise (+3mm lumps, -3mm fines) in finished product bunkers prior to dispatch.

The process entails a direct reduction of the iron ore (i.e. removal of oxygen from the ore) in solid state to metalize the ore at a ‘critical’ temperature to make this possible.