As is typical in any metallurgical process, sponge iron manufacturing is highly sensitive to raw material characteristics that would help obtain the rated capacity and the desired product quality. Hence, 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.A state-of-the-art modern R&D facility has been established along with a chemical laboratory to conduct the monitoring process.
During sponge iron manufacturing, iron ore is reduced in solid state. Unlike the conventional steel melting processes, the gangue content of iron ore cannot be separated as a slag. Hence, it becomes essential to select an ore with high iron content and a low gangue content, to optimise yield during steel making. In order 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 in the Northern part of Orissa, Tata Sponge enjoys proximity to good iron ore reserves, effective for sponge iron manufacturing. The Company sources its iron ore from the mines of Tata Steel in Joda, which offers one of the finest quality iron ore in the region.
The imperatives, which determine the quality of coal, are as follows:
- Chemical properties such as fixed carbon, ash content, volatile matter, etc.
- Physical properties viz, reactivity and ash fusion temperature.
Tata Sponge acquires good quality coal from the collieries of Central Coalfields, South Eastern Coalfields & Mahanadi Coalfields. Besides, to maintain the desired quality and improve kiln campaign life, the company also imports coal from South Africa and purchases washed coal.
Dolomite is an important ingredient and acts as a desulphuriser removing sulphur from the feed mix during the reduction process.It is mixed in small proportions along with other raw materials before charging into the kiln.Control of sulphur content is an essential pre-requisite for the manufacture of good quality steel. Tata Steel’s Gomardih dolomite quarry caters to the Company’s overall requirement of dolomite.