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Metallurgical Coke Production

AUTHOR: Gordon R Couch
DATE: December 2001

The various factors affecting the use of coking coals in connection with iron ore refining for the production of steel are discussed. It is well established technology, but one that has become considerably more efficient in recent years. Blast furnaces involve high capital cost, as do conventional coke ovens which supply them with an essential process ingredient. Some coke has been substituted in the blast furnace by other materials, notably pulverised coal, but this has resulted in even stronger coke being required for the smaller quantity which is used. All the evidence is that coke (produced from prime coking coals) will continue to be a basic raw material, for pig iron/steel production.

Over ninety per cent of coke is produced in conventional slot-type coking ovens, and this methods is likely to dominate for at least the next ten or fifteen years. Modern by-product coke ovens represent a mature technology, but nonetheless have a number of design and operational limitations. With the right blend of coals, they can consistently produce high quality coke. Because of pressures to reduce production costs, and increasingly stringent environmental requirements, a great deal of technical effort has been put into making ovens more efficient and into emission reduction.

Development work is proceeding on alternative methods of coke production and of iron refining, but much more work is needed to establish these on a commercial basis. Most of the new processes tried have turned out to be somewhat more difficult and complex than was originally envisaged.

Steel demand is likely to remain high, and the blast furnace/basic oxygen furnace route will continue to dominate. There are, however, short-term problems due to overcapacity in the steel industry. Coke producing capacity, while currently also in surplus, may not remain so as older batteries are closed down. Internationally traded coke, is playing a growing role in meeting coke demand in some places. More than half of this is coming from China.