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Sponge Iron

To make its mark in the industry Prakash Industries Ltd has ventured into activities that have led the company transform into a cohesive Steel and Power producing unit. For this, Prakash Industries Ltd setup Sponge Iron Kilns at Champa (Chattisgarh) in technical collaboration with Lurgi Germany.

Quality has been the essence of every activity at Prakash Industries Ltd. Besides emphasis on supply of quality products, Prakash Industries Ltd has always looked forward to maximize the utilization of its resources. These are the measures that have helped the company move at faster growth rate with significant reduction in the cost of production.

Being an integrated Steel and Power Company, the company has used the high quality Sponge Iron produced in the Sponge Iron Kilns for its internal consumption in its own steel plant. This not only enables cost effective manufacturing of steel but also ensures consistent availability of quality raw material for its finished steel products.

The manufacture of sponge iron entails the de-oxidisation of iron ore through the direct reduction. Direct reduction is a process by which metallic iron is produced by the reduction of iron ore below the melting temperature of iron. The production technology of DRI has two distinct routes.

In India, generally, the solid reduction process is used for producing DRI, in particular, in areas where natural gas is not easily available and where coal is easily available.

 

Solid reduction process

Where non – metallurgical coal can be used as a reduction agent

Sponge iron is a highly processed form of iron ore which contains metallic iron in the range of 83-88% obtained by direct reduction without melting it. Due to high porosity, the resulting iron is called sponge iron. It is used as a raw material for manufacturing steel through electrical arc furnace and the induction furnace routes. Considering the fact that large quantity scrap required for manufacturing steel and supply of which is irregular, sponge iron is a substitute offering regularity in supplies and quality.

In the solid reduction process iron ore is converted into DRI in a rotary kiln fired by non-coking coal.  Iron ore, coal and dolomite in pre-measured quantities are fed into the kiln, which is rotated at a speed of about 0.5 RPM. A temperature of 1,000 to 1,050 degrees is maintained through 70% of the kiln length towards the discharge end side for required reduction. The non-discharge end of the kiln i.e. 30% is the preheat zone, where the material is heated to 850 degrees. The rotating kiln functions as a heat exchanger, a chemical reactor and conveyor of solids. The inner face of the kiln is lined with castables. Air required for burning of the combustibles and for maintaining the desired temperature profile is introduced through air tubes provided at certain intervals along the length of the kiln.

These air tubes are connected to individual shell mounted secondary air blowers and air is supplied inside the kiln through submerged air nozzles through secondary blowers. The hot product discharged from the kiln is indirectly cooled in a rotary cooler by spraying water on the shell of the cooler. The discharge from the cooler is conveyed through a belt conveyor screened and magnetically separated. Sponge iron and non-magnetic components are separated and stored in separate bins for further transfer.