Abstract

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 (~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 × 10^–02 to 6.73 × 10^–02 min^–1 and R² 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.

中文翻译：

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尼日利亚 Benue Trough 和 Anambra 盆地选定煤的物理化学、矿物学、热学和动力学特征

摘要

这项研究检查了选定的尼日利亚煤炭的物理化学、矿物学、热学和动力学特征，即：来自 Benue Trough 和 Anambra 盆地的 Chikila (CHK)、Lafia Obi (LFB) 和 Okaba (OKB)。物理化学分析揭示了显着的碳、挥发性物质、固定碳和更高的热值（~25-30 MJ/kg）以及低含量的水分和灰分。推断的性质表明次烟煤到烟煤。形态、微观结构和元素分析显示具有玻璃光泽的不均匀大小的煤颗粒，其归因于石英、氧化铝、高岭石、赤铁矿和其他粘土或硅铝酸盐矿物。氧化条件下的热分析表明煤样具有高反应性，导致显着降解，这在大量质量损失中很明显（M _L = 91.59–94.04)% 和低残留质量 ( R _{M = 5.96–8.41)%，对于}M _L，按 LFB > OKB > CHK 的顺序发生，而R _M是 CHK > OKB > LFB。活化能 ( E _a ) 的动力学分析值从 30.07 到 43.91 kJ/mol，频率因子 ( A ) 从 1.16 × 10 ^–02到 6.73 × 10 ^–02 min ^–1和R ²从 0.98–0.99，基于 Coats–红蕨模型。动力学分析表明煤具有高反应性，适合能量回收。