CO2 reactivity of briquettes derived from discard inertinite-rich Highveld coal using lignosulphonate and resin as binders

Abstract

South African collieries generate approximately 31 Mt of fine and ultrafine coal annually, with the majority of the ultrafine fraction discarded in slurry ponds and underground workings. Use can be made of this energy source through briquetting, thereby alleviating the handling problems associated with fine coal. Briquettes of inertinite-rich high-ash coal when combined lignosulphonate and resin have shown promising mechanical strength, therefore requiring reactivity analysis. In this study, chars derived from lump coal, binderless briquettes, and lignosulphonate- and resin-bound briquettes were subjected to CO2 gasification at 875, 900, 925, 950, and 1000°C. Binder addition brought about no distinct difference in char reactivity. The briquetted chars showed approximately double the reactivity of lump coal chars. The increase in micropore surface area derived during the devolatilization process is postulated to be the major contributor to the increased reactivity of the briquettes. No significant differences were observed between the activation energy of the lump coal and manufactured briquettes, with values ranging between 222–229 kJ/mole. Industrial implementation of fine coal briquetting in South Africa will result not only in an increase in coal resources, but also reduce environmental concerns linked to fine coal discards