Sponge Iron will be iron metal lessened straightforwardly in strong state utilizing coal gas, natrual gas or coal as reductants and is otherwise called Directly Reduced Iron (DRI). The requirement for improvement and commercialisation of wipe iron assembling process emerged in late 50's when Electric Arc Furnaces (EAFs) occupied with assembling steel began confronting issues of accessibility of scrap of craved quality, the customary wellspring of their iron metallics.

Different innovations produced for the assembling of wipe iron might be delegated:

A. Gas Based Technologies

Fluidised Bed Technologies

Innovations utilizing hydrogen as reductant

Innovations utilizing carbon monoxide as reductant

Innovations utilizing blend of both hydrogen and carbon monoxide as reductant

Static bed innovations utilizing blended gas as reductant

Moving bed advances utilizing blended gas as reductant

The gas based advances were equipped for utilizing either common gas connected with oil or lessening gas got from coal.

B. Strong Reducant or Coal Based Technologies

Out of the few advances grew just a couple were turned out to be financially fruitful; the plants taking into account the others like Purofer, Armco, Wiberg Sodefors, NSC, Plasma red and Usco were either shut down or disassembled for different reasons. The achievement of a portion of the advances was restricted to a couple plants of little limits as it were.

Capital Equipment Required for DR Processes:

The basic equipment required for the gas based plants is:
Natural gas reformer
Reduction reactor/shaft kiln
Reducing gas heater
CO2 removal unit
Reducing and cooling gas compressors
Cooling water circuits for equipment and for process gas
(viii)
Boiler feed water system
Inert gas generation system
Raw materials and product handling systems
Instrumentation and control system

The basic capital equipment required for the coal based processes is:
Raw materials handling and feeding system
Rotary kiln with air injection and coal blowing systems
Rotary cooler
Product separation and handling System
Waste gas cleaning system
Briquetting system
Electrical system
Instrumentation and control system

The capital investment made by existing DRI plants is summarised
below:
Plant Capacity Year of commis- Investment
TPA sioning Rs. crores

SIIL, Unit 1 30,000 1980 11.8
SIIL, Unit 2 30,000 1985 8.2
OSIL 1,35,000 1984 39.8
IPITATA 90,000 1986 35.0
BSIL 1,50,000 1989 112.0

The present necessity of capital venture for littler size (up to 60,000 TPA) coal based plant receiving indigenous innovation shifts between Rs.6500 to Rs.8000 per ton of yearly introduced limit. In this manner, the capital venture for 30,000 TPA plant taking into account this innovation has been demonstrated to fluctuate between Rs.45 crores to Rs.49 crores.