The predicted increase in steel demand in Asia will provide opportunities for the establishment of
newer steel making technologies in preference to the traditional technology of the integrated blast
furnace. The two new processing routes will be direct reduction of the iron ore (DRI) to produce
a feedstock, as an alternative to scrap, for the Electric Arc Furnace (EAF), and direct smelting
processes. The smelting reduction processes do not require the use of coking coal or scrap iron,
rather they are able to use iron ore or DRI and thermal coals directly.
A number of Direct Smelting processes for the direct production of hot metal from iron ore or
DRI are being developed around the world. This is being driven by the desire for:
- the ability to utilise cheaper and more abundant raw materials such as non-coking coals and
non-agglomerated ores,
- smaller economic plant sizes and,
- reduced capital costs and environmental problems through the elimination of coke ovens and
sinter/pellet plants.
The benefits are:
- competitive hot metal,
- flexibility of operation, and
- the product can be fed to an EAF for steelmaking.
The metal produced from such processes is a premium grade product which has a high value in
use to an EAF steelmaker compared to alternative DRI materials.
At this stage the only direct smelting process that is in commercial operation is the COREX
process with plants operating in South Africa, Korea, India and the USA. The COREX process is
a two-stage process. In the first step the iron ore is reduced in a shaft furnace. In second step the
reduced iron ore is melted in the melter gasifier using the energy generated from the gasification
(and partial combustion) of coal. The reducing gas produced in this second stage is used in the
shaft furnace.
The coal used in the COREX process must supply heat for the devolatilisation of
the coal, the
gasification of the char and the melting of the reduced iron from the reduction shaft. It must also
provide sufficient gas to the reduction shaft to reduce the iron ore feed. Coals most suited for use
with the COREX process have an air dried fixed carbon content from 55 to 70%. Many coals
from the Bowen Basin within Queensland are suited to the COREX process and several mines
currently supply POSCO’s plants in Korea.
This is to ensure good gas flow within the melter gasifier and to reduce the carry over of coal
and/or char. The amount of fine coal (minus 5 mm material) that is fed to the COREX process
must be minimised. Therefore all coals must be sized or agglomerated before use.
There are many alternatives to achieve minimum fines content depending on the facilities at the
loading port, discharge port and COREX® plant. The flexibility of Queensland coal export
terminals allows the sizing and blending of coals at the loading port to meet the needs of
COREX® operators.
