Maximisation of non-coking coals in coke production from non-recovery coke ovens

Abstract

The blast furnace has been, and is likely to remain, the dominant technology for ironmaking. Coke is fed to blast furnace as a fuel and its quality plays a significant role in controlling the performance of the furnace. The quality of coke depends on the quality of coal or its blend, coking parameters and precarbonisation techniques, if any. With decreasing availability and increasing cost of good quality hard coking coal, coke makers face a tough challenge for production of metallurgical coke at competitive rates. Coke quality has been enhanced in recent times by introduction of precarbonisation techniques, such as compaction of the blend into cakes, so as to improve its bulk density. JSW Steel has adopted the newly developed vibrocompaction precarbonisation technique, along with non-recovery ovens, having a capacity to produce 1˙2 Mtpa of coke. Optimisation of coal blend and bulk density of cake produced from vibrocompaction has helped JSW use inferior coals up to 35% in the coal blend, without adversely affecting the coke quality. The present paper discusses the optimisation of bulk density and coal blend, and use of non-coking coals in the coal blend to obtain the desired coke with properties: coke strength after reaction (CSR) exceeding 64%, coke reactivity index (CRI) <25% and Micum index (–10 mm) (M10) <6%.