The correlation between reactivity and ash mineralogy of coke

Rautaruukki is a modern integrated Finnish steel works having a production of 2.4 mil. t/year of flat products. The total fuel consumption of the two blast furnaces in 1994 was 435 kg/t HM. Coke used was 345 kg/t HM and oil injection was 90 kg/t HM. The coking plant was taken in to operation in 1987 and is the only one in Finland, which means that the coking tradition is very short. Coke production is 0.9 mil. t/year. The coking blends include 70--80% medium volatile coals having a wide range of total dilatation. From time to time disturbances in the operation of the blast furnaces have occurred in spite of the fact that the reactivity of the coke used has remained constant or even decreased. It was thought necessary to investigate the factors affecting coke reactivity, in order to better understand the results of the reactivity test. This paper deals with carbonization tests done in a 7 kg test oven using nine individual coals having volatile-matter contents of 17--36% (dry) and seven blends made from these coals. Coke reactivity with CO{sub 2} at 1100 C (CRI) and coke strength after reaction (CSR) were determined using the test developed by themore » Nippon Steel Corporation. The influence of coke carbon form, porosity and especially ash mineralogy on the coke reactivity were examined. The effects of some additives; petroleum coke (pet coke), the spillage material from the coke ovens and oxidized coal, on coke quality were also studied. Typical inorganic minerals found in coals were added to one of the high volatile coals, which was then coked to determine the affect of the minerals on the properties of the coke produced.« less