Effect of sawdust addition on coking pressure produced by two low vol bituminous coals

•No interaction between coal and sawdust was observed by TGA.•Pine, chestnut and oak sawdust produced a decrease in coking pressure.•The effect of sawdust and torrified sawdust addition was similar.•Additions of around 2 wt% reduced coking pressure without impairing coke quality.

Two high-rank bituminous coals and three sawdusts of different origin were selected to study the effect of biomass on coking pressure. The effect of the biomass on the thermoplastic properties of the coals was assessed by means of the Gieseler test. In addition, the effect of the biomass on the thermal decomposition of the coals was studied by means of thermogravimetric analysis together with the modification of the permeability of the coal plastic phase. The individual coals and the blends were carbonized in a 17 kg movable wall oven; the coking pressure developed was measured and the quality of the resulting coke was assessed. It was found that the sawdust reduced coking pressure, especially in the case of the coal that developed the highest coking pressure. This effect was attributed to the modification of the permeability of the plastic phase to gas flow. It was concluded that although the addition of sawdust produces a decrease in coking pressure, additions should be limited to small amounts to avoid excessive deterioration of the quality of the product.