Raw materials for Corex and their influence on furnace performance

Abstract

The scarcity of good quality coking coal for the blast furnace (BF) has made steel makers look for an alternative iron-making process that requires little or no coke. The Corex process has been developed as an alternative to BF iron-making, which uses non-coking coal and a small amount of coke as fuel, and pellet/lump ore as iron-bearing feed. JSW Steel operates two Corex units each of 0?8 Mtpa, commissioned in 1998 and 2001 respectively. Iron oxides and non-coking coals have to meet certain physical, chemical and high temperature properties for stable operation and to attain high performance levels. Experience of the Corex operation with various coals and iron oxides over the years has helped in understanding the influence and sensitivity of raw materials on its performance and develop new raw material specifications. Statistical analysis of plant data showed that the significant parameters affecting fuel rate and production are moisture, volatile matter, char strength after reaction of coal, reduction disintegration index (RDI; %, -6?3 mm) of pellets and slag rate. This helped achieve the most efficient operating parameters, surpass rated capacity and utilise steel plant waste. The present paper brings out the impact of various raw material properties, and the modified specifications of coal and iron oxides for Corex.

Coal use in iron and steel metallurgy

“…The tapping procedure, tapping temperature and further processing of the hot metal are the same as with blast furnace hot metal. The Corex ® process requires a high amount of non-coking coal (750-950 kg/tHM) with well-defi ned properties and some amount of coke (10-20%, usually 50-150 kg/tHM) for heat generation, production of reducing gases and to maintain char bed permeability (Prachethan Kumar et al ., 2009). Coal should satisfy certain physical, chemical, physico-chemical, physical and mechanical properties.…”

Smelting process of direct reduction iron bearing Ni and Cu to prepare Fe-Ni-Cu ternary alloy

“…Concerning kinetics, the optimum basicity can decrease the slag viscosity and facilitate S transfer from the metal to the slag-alloy interface, thereby improving the desulfuration reaction in the smelting process [30,31].…”

Structure characterization and metallurgical properties of the chars formed by devolatilization of lump coals

“…The Corex process emerges as a more environmentally friendly alternative to the blast furnaces for the melting reduction process, which allows using non-coking coal as a fuel to take the place of cokes. So far, the primary Corex C-2000 including Saldanha Steel in South Africa and Jindal Vijayanagar Steel Limited in India have the capacity of 0.65 and 0.8 mtpa, respectively, and the Corex C-3000 of Baosteel in China has expanded to 1.5 mtpa capacity [9][10][11]. Although the share of production by the Corex process is very low compared with a world production of 1.5 btpa, the Corex process is one of the most successful technologies in the emerging ironmaking processes.…”