COREX

COREX is an ironmaking technology that uses coal as the primary reducing agent to produce direct reduced iron (DRI) and, in a subsequent stage, molten iron, without relying on coke ovens. The system integrates a reduction shaft and a melter-gasifier in a two-stage configuration to convert iron ore into sponge iron and then into liquid metal.

In operation, iron ore, typically in the form of pellets or lumps, is fed to the reduction shaft where it is reduced by hot reducing gas produced in the melter-gasifier from coal. The reduced material, or sponge iron, is then processed in a smelting section where it is melted and refined. The process also generates off-gases that can be used to generate energy or heat, contributing to overall energy efficiency.

COREX can utilize non-coking coal and iron ore fines, allowing feedstock flexibility beyond traditional coke-based routes. The gas produced in the melter-gasifier serves as the reducing agent in the shaft, and the system is designed to recover energy from waste gases for additional use.

Advantages commonly associated with COREX include the elimination of coke ovens, the ability to work with non-coking coal, and potential reductions in capital cost and emissions relative to conventional blast-furnace routes. Limitations reported in practice include the complexity of the plant, variable operating costs depending on feedstock prices, and a smaller global footprint of operating plants compared with established BF-BOF systems.

History and deployment of COREX began in the late 20th century as an alternative to coke-based ironmaking. Several plants were constructed and operated in subsequent decades by various steel producers and engineering groups, with ongoing development and licensing of the technology by its developers and licensors.