The main cost benefit of PCI is the replacement of high cost coking coal.  The amount of coke replaced by an injected coal depends on the useable energy released by the PCI coal in the lower zone of the BF.  This energy is the partial combustion heat released when coal is gasified to CO and H₂  less the sensible heat of the combustion gases and ash.

There is an economic injection rate, namely the injection rate at lowest total coal costs, for every BF.  This rate depends on the coke quality and the cost of coking and PCI coals.  Most BF’s have PCI systems that can achieve injection rates greater than the economic rate.

The value-in-use benefit of PCI depends on its replacement ratio and its impact on the energy balance of the steelworks.  The costs/benefits associated with changes to the energy balance of a steelworks depend on the costs of the alternative fuels.