Characterization and ash chemistry of selected Nigerian coals for solid fuel combustion

Abstract

In this paper, characterization and ash chemistry of selected Nigeria coal samples were investigated to determine its suitability as a solid fuel. The three coal samples considered originated from Northern Benue trough, Central Benue trough and Anambra Basin of Nigeria where proven reserve deposits are found. The coal samples were analysed using various analytical methods such as thermosgravimetric analysis (TGA) and X-ray Fluorescence spectroscopy (XRF) analyses. The ash chemistry indices used in predicting the performance of the coal samples includes basic to acidic oxide (B/A), silica ratio, iron index and sulphur slagging index (Rs). The TGA profile suggests that Enugu coal showed high thermal stability than that of Okaba and Maiganga coals but had an ash content higher by a factor of 2.0 when compared with Okaba and Maiganga coals. Maiganga coal however has the highest heating value of 27.40 MJ/kg when compared to Okaba coal (25.74 MJ/kg) and Enugu coal (22.92 MJ/kg). The silica ratio indicated that Enugu coal has high slag volume, while the B/A suggest that all the coals were found to be less than 0.6 indicating low slagging potential. The comparison of the ash chemistry suggests that Maiganga coal has lowest slagging potential while Enugu coal highest slagging potential.