The response of inertinite-rich Witbank coals (South Africa) to rapid heating was evaluated using petrography, selected Nuclear Magnetic Resonance (NMR) and X-Ray Diffraction (XRD) structural parameters. A total of thirteen (13) coal samples were collected from the No. 2 Seam; a set of six (6) samples from the western and the eastern sides of a ~ 0.4 m thick dolerite dyke emplaced into the coal seam at 0.25 m intervals. An unaltered coal (Un-C; the 13th sample), collected away from the dyke but within the same seam at the mine, was included for comparison. All 13 coal samples were dominated by inertinite. Semifusinite was most abundant in the samples from the western side of the dyke, whereas the proportion of inertodetrinite was highest in samples from the eastern side. Due to very low vitrinite contents, mean random total reflectance (%RoTmr) was used to compare the maturity of the inertinite-rich coals. A decrease in volatile matter was correlated with an increase in mean random total reflectance (%RoTmr; measured on semifusinite, inertodetrinite, and vitrinite), the latter used as a potential maturity indicator for the thermally altered inertinite-rich coals. Mean random total reflectance rose from a background value of 1.52%RoTmr (for Un-C) to 2.83%RoTmr for the coal sample at the western coal-dyke contact (0.0 m). The corresponding reflectance values for the thermally altered coals from the eastern side were less consistent, decreasing closest to the dyke (1.93%RoTmr for the sample at 0.0 m); this trend is also reflected in the NMR and XRD parameters. Eight (8) samples were selected for the NMR analysis, representative of the maceral composition and maturities of the coals investigated. For Un-C, the fraction of aromatic carbons (fa) was 0.88 (average number of carbons per aromatic cluster (C) = 17), and the interplanar spacing (d002) was 3.48 Å (with a crystallite height of 22.09 Å). For the thermally altered coals from the western side, fa decreased from 0.96 at the coal-dyke contact (C = 26 for sample at 0.0 m) to 0.92 for the sample at 1.25 m from the dyke (C = 20). For samples from the eastern side, fa increased from 0.91 (C = 19 for the sample at 0.25 m) to 0.93 (C = 23 for sample at 0.5 m), before decreasing to 0.89 further from the dyke (C = 18 for sample at 1.25 m). In general, the d002 values for the thermally altered coal samples were larger than for graphite. Similarly, only marginal increases in crystallite heights were observed. Although the dyke induced coal maturation and the resultant increase in fa, the overall lack of graphitic order in the thermally altered coals was ascribed to the limited thermal energy provided by the relatively thin dyke; increased heat input would be required to effect significant structural changes in the inertinite-rich coals. Differences between the two sets of thermally altered coal samples were attributed to the emplacement dynamics of the igneous intrusion, which require further investigation.

使用岩相学、选定的核磁共振 (NMR) 和 X 射线衍射 (XRD) 结构参数评估富含惰性的 Witbank 煤（南非）对快速加热的响应。从 2 号煤层共采集了十三 (13) 个煤样；一组六 (6) 个样本，它们来自以 0.25 m 的间隔置入煤层中的 ~ 0.4 m 厚辉绿岩岩脉的西侧和东侧。一种未改变的煤（Un-C；第 13 个样品），在远离堤坝但在矿井的同一煤层内收集，用于比较。13 个煤样均以惰性元素为主。岩脉西侧样品中半梭晶含量最高，而东侧样品中惰性沸石的比例最高。由于镜质体含量极低，平均随机全反射率 (%RoTmr) 用于比较富含惰性的煤的成熟度。挥发性物质的减少与平均随机总反射率的增加（%RoTmr；在半熔晶质、惰性晶质和镜质质体上测量）相关，后者用作热变质富含惰性质煤的潜在成熟度指标。平均随机总反射率从背景值 1.52%RoTmr（对于 Un-C）上升到西部煤堤接触面（0.0 m）煤样的 2.83%RoTmr。来自东侧的热变煤的相应反射率值不太一致，在最靠近堤坝处降低​​（0.0 m 处的样品为 1.93%RoTmr）；这种趋势也反映在 NMR 和 XRD 参数中。选择八 (8) 个样品进行 NMR 分析，代表所研究煤的矿物成分和成熟度。对于 Un-C，芳香碳的分数 (fa ) 为 0.88（每个芳香族簇的平均碳数 (C) = 17），面间距 (d002) 为 3.48 Å（微晶高度为 22.09 Å）。对于来自西侧的热蚀变煤，fa从煤岩接触处的 0.96（0.0 m 处的样品 C = 26）降低到离岩墙 1.25 m 处的样品（C = 20）的 0.92。对于来自东侧的样品，fa从 0.91（0.25 m 处的样本 C = 19）增加到 0.93（0.5 m 处的样本 C = 23），然后从堤坝进一步降低到 0.89（1.25 m 处的样本 C = 18）。一般来说，热变煤样品的 d002 值大于石墨。类似地，仅观察到微晶高度的边际增加。尽管堤坝引起了煤的成熟和由此产生的fa 的增加，热变煤中石墨有序的整体缺乏归因于相对较薄的岩脉提供的有限热能；需要增加热量输入才能对富含惰性的煤产生显着的结构变化。两组热变煤样之间的差异归因于火成岩侵入的侵位动力学，这需要进一步调查。