The effect of additives on coking pressure and coke quality

An industrial coal blend (ICB) normally used in cokemaking was selected for the study. A coal that is known to produce high coking pressure was added to the industrial coal blend in two percentages i.e. 20 and 25 wt.%. To reduce the coking pressure generated due to the addition of the dangerous coal to the ICB, two coals of different rank normally used in the process of pulverized coal injection (PCI) in blast furnaces and coke fines were used as additives. The pressure exerted on the oven wall was measured by carbonizing the blends in a 17 kg electrically heated movable wall oven. In addition, the permeability of the coal plastic layer was assessed. The quality of the cokes produced was evaluated by measuring their cold mechanical strength, reactivity and post-reaction strength. It was found that, although coke fines are the most effective additive in reducing coking pressure, they cause considerable impairment to coke quality. On the other hand, the low volatile PCI coal successfully reduces coking pressure without causing any great impairment to coke quality.