Reclamation of ultra-fine coal with scenedesmus microalgae and comprehensive combustion property of the coalgae® composite

Abstract

Combustion of South African discard ultra-fine coal, charcoal, microalgae biomass, and composites of the three under air were studied. The objective of the study was to determine the effect of Scenedesmus microalgae bio-mass on the comprehensive combustion characteristics (CCC) of the ultra-fines. The composites were designed with Design Expert and, unlike blending with the dry microalgae biomass, fresh slurry was blended with the ultra-fine coal and charcoal. Non-isothermal combustion was carried out at heating rate of 15 °C/min at 40-900 °C and flow rate of 20 ml/min, oxygen/ carbon dioxide (O2/CO2) air. Combustion properties of composites were determined from thermogravimetric-differential thermogravimetric analysis and analysed using multi-ple regression. On combustion, the interaction of coal-charcoal-microalgae was antagonistic (b =-1069.49), while coal-microalgae (b = 39.17), and coal-charcoal (b = 80.37), were synergistic (p = 0.0061). The coal-mi-croalgae (Coalgae) indicated first order reaction mechanism, unlike coal and the charcoal. The CCC index of Coalgae, (S-value = 4.52E8) was superior relative to ultra-fine (S-value = 3.16E8), which indicated high-quality fuel. This approach to combusting ultra-fine coal with microalgae biomass is partly renewable, and it would advance the production of heat and electricity.