CHARACTERISATION OF THE BOTTOM ASH OF THE LAFIA OBI COAL

This investigation characterised the bottom ash of Lafia Obi coal sourced from Lafia, Nassarawa State, Nigeria. The coal sample was heated to a temperature of 950oC in a closed gas kiln to obtain the cream-colour bottom ash as the coal combustion residue which was taken to laboratory for characterisation. The mineralogical composition through X-ray diffraction showed the dominant presence of quartz with other minerals in minor quantities. The elemental oxides analysis through X-ray fluorescence spectrophometry revealed SiO2 (52.90%) and Al2O3 (28.49%) as major constituent oxides among others. The total percentage of SiO2, Al2O3, and Fe2O3which are the pozzolanic content was 85.04% which ranks the bottom ash high in Class F according to the ASTM bottom ash classification. The LOI (10.20%) is high being above the 6% allowed in many countries. The ultimate analysis results reveal a high carbon content of 60.82%, which places the bottom ash as having high heating value. The low percentage of sulphur (0.01%) and nitrogen (0.5%) presents it as having less potential for releasing harmful pollutants to the environment. The thermogravimetric curve revealed the stability of the material up to a temperature of 250oC. The low onset temperature of 250oC led to a thermal degradation between 250oC and 350oC. The peak temperature was observed to be about 500oC. In conclusion, the Lafia Obi bottom has high heat content. It could also be investigated for partial replacement of cement as a result of its high pozzolanic content. The foregoing will be very economical as bottom ash is far cheaper than cement.