Physiochemical, Mineralogical, Thermal and Kinetic Characterisation of Selected Coals from the Benue Trough and Anambra Basin, Nigeria

摘要

This study examined the physiochemical, mineralogical, thermal, and kinetic characteristics of selected Nigerian coals, namely; Chikila (CHK), Lafia Obi (LFB) and Okaba (OKB) from the Benue Trough and Anambra Basin. Physicochemical analyses revealed significant carbon, volatile matter, fixed carbon, and higher heating values (similar to 25-30 MJ/kg) along with low contents of moisture and ash. The deduced properties indicate subbituminous to bituminous rank coals. The morphological, microstructure and elemental analyses revealed heterogeneous sized coal particles with a glassy lustre, which are ascribed to quartz, alumina, kaolinite, hematite, and other clay or aluminosilicate minerals. Thermal analysis under oxidative conditions indicated the coal samples are highly reactive, which resulted in significant degradation as evident in the high mass losses (M-L = 91.59-94.04)% and low residual masses (R-M = 5.96-8.41)%, which occurred in the order LFB > OKB > CHK for M-L whereas R-M was CHK > OKB > LFB. Kinetic analysis values of activation energy (E-a) from 30.07 to 43.91 kJ/mol, frequency factor (A) from 1.16 x 10(-02) to 6.73 x 10(-02) min(-1) and R-2 from 0.98-0.99 based on the Coats-Redfern model. The kinetic analysis indicated the coals are highly reactive and suitable for energy recovery.