Structural transformation of agricultural waste/coke blends and their implications during high temperature processes

Abstract

With a sharp increase in demand and production, palm oil wastes, (i.e. empty fruit bunches, fibre and shells) are generated, out of which a large amount ends up in landfill. In such a context, alternative solutions are needed to reduce the impact of these agricultural wastes on the environment. The present paper investigates the effect of addition of agricultural waste materials on the combustion behavior of its blends with metallurgical coke (MC). Two types of agricultural waste materials, palm shell and coconut shell, were mixed in different proportion with MC, while the gas phase reactions were studied at 1 200°C in a drop tube furnace (DTF). In the tested conditions, the blends containing agricultural waste materials indicated higher combustion efficiencies compared to MC alone. Carbon structure analysis were performed through 13CP/MAS NMR spectroscopy showing various groups of carbons present in the agricultural waste samples ranging from aliphatic to aromatic carbons. The morphology of the samples was studied through Scanning Electron Microscope (SEM). SEM provided a qualitative description of the pore structure in the raw samples as well as the changes occurring following the gas phase reactions in the DTF. It was found that the particles derived from the wastes became increasingly deformed and lost their cell lumen. Surface area measurements were found to be in good agreement with the SEM images, supporting the higher combustion efficiency of the blends in comparison to coke alone. The present study suggests that agricultural waste materials have the potential to partially replace MC, as an auxiliary fuel in metallurgical processes. © 2011 ISIJ.