India is the world’s largest producer of sponge iron, most of which is produced primarily through the coal based method of production. Growth in the sponge iron production can be attributed largely to the popularity of secondary steelmaking route, which has shown a phenomenal growth in India. The proportion of crude steel produced by the secondary steel sector rose from 26 mMT(37%) in 1999-2k to 54 mMT(59%) in 2007-08. This has been mainly due to the lower investment cost of the EAF as compared with the integrated blast furnace–oxygen converter route and also because of its greater flexibility of product mix.
The process of sponge iron manufacturing involves removal of oxygen from iron ore. When that happens, the departing oxygen causes micro pores in the ore body, turning it porous. When the eventual product is observed under a microscope, it resembles a honeycomb structure, which looks spongy in texture. Hence the name sponge iron.
Sponge iron is an iron source relatively uniform in composition, and virtually free from tramp elements. It is used increasingly in Electric Arc and Induction furnaces to dilute the contaminants present in the scrap used in these processes. It has an associated energy value in the form of combined carbon, which has a tendency to increase furnace efficiency. For captive DRI production facilities, there is an added advantage that the delivery of hot DRI to the furnace can reduce energy consumption to 16 – 20%.
Tata Steel LP produces high-grade sponge iron that is consistent in quality. The Company has an annual manufacturing capacity of 390,000 tonnes of sponge iron from its 3 kilns. The production process followed at Tata Steel LP makes it unique and superior than its competitors.
Various properties of sponge iron typically produced at Tata Steel LP:
Lump: +3 mm
Fines: 0-3 mm
Bulk density : 1.9-2.2 MT / m3