Using a new classification scheme developed under ACARP, the Spontaneous Combustion Testing Laboratory at the University of Queensland assessed coal quality data from the Surat Basin coals and found some interesting results.
âIt is imperative that each new deposit is assessed on its own merits and ply-by-ply variations are measured to identify the site-specific relationships for each deposit. This will assist in developing appropriate hazard management plans,â UQ Spontaneous Combustion Testing Laboratory director Basil Beamish said.
To date there is no published data on spontaneous combustion index testing of Surat Basin coals. âHowever, coal quality data is available that can be used to gain an initial indication of the propensity of these coals to spontaneously combust,â Beamish said.
Surat Basin coals generally range in rank from subbituminous A to high volatile C/B bituminous and could therefore be expected to be reasonably reactive based on the simple principle of increasing propensity for lower rank coals.
In his research Beamish used simple coal quality relationships identified as part of ACARP Project C12018.
The most recent of these relationships has been established from the UQ database of R70 values for coals ranging in rank from subbituminous C to low volatile bituminous.
Applying this relationship to Surat Basin coal data published in the 14th edition of Queensland Coals produces some interesting results, Beamish said (see below figure).
Beamish said there was a significant variation in the R70 values as a result of coal rank and possibly coal type influences.
Generally, there appeared to be three distinct groupings. Two of these groups match the measured results obtained for Dunn Creek (Wilkie Creek, Haystack Road and Rywung) and Trap Gully (Horse Creek, Collingwood and Sefton Park). However, the Dunn Creek and Trap Gully deposits from the Callide Basin are a different coal type with high inertinite contents, compared to the Surat Basin coals which have high liptinite contents, Beamish said.
âIt is generally considered that liptinite is more reactive than inertinite in terms of spontaneous combustion. Therefore, it is possible that the measured values for the Surat Basin coals could be even higher than the predicted values,â he said.
âThe Culgowie, Glen Wilga, Elimatta, Wandoan and Kogan Creek deposits display elevated R70 values for which there is no mining analogue in Australia. Again these coals have high liptinite contents and the measured values may be even higher than shown in the figure.â