In the Corex process, all metallurgical work is carried out in two separate process reactors – the reduction shaft and the melter gasifier. Because coking and sintering plants are not required, and a lower-cost coal compared to the blast furnace route can be used, substantial cost savings of up to 20% can be achieved in the production of hot metal. Corex plant emissions contain only insignificant amounts of NOx, SO2, dust, phenols, sulfides, and ammonia, so emission values come in below the maximum values permitted by European standards. Furthermore, waste-water emissions are far lower compared with the conventional blast furnace route.
Advantages of the Corex
Direct use of non-coking coal
The coal is charged inside the melter gasifier, so even non-coking coal can be used, which makes a coking plant unnecessary. The high dome temperature exceeds 1,000°C, resulting in cracking of the coal’s relieved hydrocarbons and avoiding the formation of tar. The cost of Corex coal is approximately 40% lower than for coal used in blast furnaces.
High proportion of lump ore
The typical iron oxide mix for Corex is 100% pellets, even a stabile operation by use of lump ore fraction up to 80% is possible. The iron ore mix depends on the price of lump ore available. In addition, no sinter – and therefore no sinter plant is necessary for optimal operation.
Use of pure oxygen
Blast furnace operators strive to enrich the hot blast with oxygen, but nitrogen is a burden to this process. Corex already uses high-purity oxygen, resulting in a nearly nitrogen-free top gas. Because of its high calorific value, this gas can be recycled for reduction work, used for heat/energy generation, or to produce ethanol and acidic acid using the LanzaTech process, designed by Primetals Technologies. Depending on the steelworks’ requirements, additional value can be created with the produced gas.
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Fig.1- Briquetting of by-products
Type of plant: 2 x Corex C-2000 with a Corex-gas based Midrex DR-plant
Customer: Jindal South West Steel Ltd. (JSW), Toranagallu, India
The challenge of this project was to build up a green-field, economical operating iron-production plant, located in an isolated area with limited access to fuel gas. Two Corex C-2000 plants producing hot metal were the basis of the following steel production. As a special feature, plant wastes such as limestone/dolomite fines and LD-converter slag are recycled into the two Corex modules. The combination of Corex and the blast furnace helped JSW to maximize the utilization of solid waste and thereby reduce the cost of hot metal. In addition, Corex export gas is used to produce DRI and as a backup in blast furnace stoves, boilers, in the sinter and pellet plant.