Coal and coal-shale undergo low-temperature oxidation when exposed to air, potentially leading to spontaneous combustion. Coal-shale found in association with coal seams vary considerably in their intrinsic properties and spontaneous combustion liability index. Fourteen coal-shale samples collected from four different coal mines in Witbank Coalfield, South Africa, were experimentally investigated. The influence of coal-shale intrinsic properties and spontaneous combustion liability indices（determined by the WitsEhac Index and the Wits-CT Index） were established. The liability indices indicate relationships with the intrinsic factors and thus, identifying the major intrinsic factors affecting liability toward spontaneous combustion in these coal-shale samples. The XRF analysis indicated that the coal-shale samples are rich in Si O2, Al2 O3 and Fe2 O3, while the XRD showed that same coal-shale samples are generally dominated with kaolinite and quartz. The coal-shale occurred in association with medium Rank C bituminous coal and contained varying proportion of macerals. The Wits-Ehac Index was unable to reliably determine liability indices of some coal-shale samples, and hence the Wits-CT Index was developed. The results obtained from the characterisation tests may be used as a tool to predict the spontaneous combustion liability in carbonaceous material and may serve as a reference when comparing coal-shale from different coal mines.
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