Coal Blend Rank Changes and Resultant Coke Quality from IHCC Heat Recovery Cokemaking

摘要

On the basis of this study, the following conclusions are made:Since the 1998 IHCC startup, the coal blends show a dramatic increase in coal rank and a dramatic drop in fluidity. Despite the dramatic change in coal rank and fluidity, coke strength properties remained high. An increase in coal blend rank shows a trend in a decrease in coke VM and coke CSR, as well as an increase in stockline coke size and coke porosity. Stockline size was the only coke quality parameter that showed a trend with coal quality parameters. Large stockline size seems to be associated with a lesser expanding coal blend. Comparison of heat recovery cokemaking vs. by-product cokemaking for high and low VM blends does not indicate much improvement in coke strength properties for the LVM blend. However, there is an improvement in coke strength properties for the HVM blend. Compared to the slot oven coke, heat recovery coke has a higher pyrolytic carbon content. However, the pyrolytic carbon content decreases with increasing rank. The carbon form content for heat recovery vs. slot oven coke indicates no change in the MSI for the HVM blend. However, for the LVM blend, a significant increase in MSI was observed for the slot oven coke, in which acicular (needle) and ligular (ribbon) carbon forms increased at the expense of isotropic and granular carbon forms, suggesting enhancement under pressure this study indicates that besides measuring coke quality parameters, the stockline simulator test should be used when new coal blends are evaluated via the six-oven carbonization test. Larger stockline coke size, coupled with extremely high CSR, excellent abrasion and impact strength properties, would result in larger-sized coke and lesser coke fines at the granular zone and raceway, which should positively affect blast furnace permeability, stability and productivity.