Raw Materials
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Sponge iron manufacture is highly sensitive to raw material characteristics. Therefore, it is essential to examine the chemical and physical characteristics of raw materials, both individually and in combination. The basic raw materials for the production of sponge iron are iron ore, non-coking coal and dolomite. Several tests are conducted in the company laboratory to ascertain their suitability in a rotary kiln.
Coal
Important factors determining coal quality are:
- Chemical properties such as fixed carbon, ash content, volatile matter, etc.: &
- Physical properties viz, reactivity and ash fusion temperature.
TSIL sources its entire coal requirement from the subsidiaries of Coal India Limited, which are known for their high quality coal reserves.
Iron Ore
In sponge iron making, iron ore is reduced in solid state. Unlike in the conventional steel melting processes, the gangue content of iron ore cannot be separated as a slag. Therefore, it becomes imperative to select an ore with a high Fe content and a low gangue content, to optimise yield during steel making. Apart from this, to ensure a better kiln campaign life and output, the iron ore is made to undergo a series of other tests viz. shatter, tumbler & abrasion indices, reducibility etc.
By virtue of its location, TSIL enjoys the proximity of good iron ore reserves, suitable for sponge iron making, in the Northern part of Orissa. TSIL sources its iron ore from the Khondbond Mine of Tata Steel, which has one of the finest quality iron ore in the region.
Dolomite
Dolomite acts in the process as a desulphuriser, removing sulphur from the feed mix during the reduction process. It is mixed in small proportion along with other raw materials before charging into the kiln. TSIL’s entire requirement of dolomite is obtained from Tata Steel’s Gomardih dolomite quarry.