Williams, B, Donaldson, K & Beamish, B 2019, 'Risk profiling and control of spontaneous combustion for coal mine closure', in AB Fourie & M Tibbett (eds), Proceedings of the 13th International Conference on Mine Closure
, Australian Centre for Geomechanics, Perth, pp. 563-576.
The Leigh Creek Coal Mine, located approximately 550 km north of Adelaide in South Australia, operated between 1944 and 2015.
The coal, being a low rank sub-bituminous coal, is prone to self-heating and localised spontaneous combustion. Throughout the many decades of mining operation a significant body of knowledge was generated regarding the causal factors and more effective treatment strategies for spontaneous combustion. These strategies were effectively suited to an operational mine site, but not specifically designed, nor tested, for closure.
A swift decision to close in June 2015, followed by a short mining operations shutdown period, presented significant operational, technical and regulatory challenges. The subsequent joint risk mapping process employed by Flinders Power and South Australian Mining Regulators was a unique example of obtaining realtime objective evidence through leading-edge science in order to inform the risk profile, determine the appropriate risk management strategies for closure and develop an appropriate mine closure plan.
In developing the risk assessment for closure, the following three key assumptions needed to be tested.
These assumptions were founded on operational experience and expert advice, however applicability to a rehabilitation phase had not been validated for the site.
To address these uncertainties extensive laboratory test work and a unique field trial installation on an area of active combustion was conducted. The testing of these assumptions formed the basis of the rehabilitation specification, area-specific rehabilitation designs and subsequent completion criteria. The use of a risk and evidentiary-based approach to categorise spontaneous combustion hazard likelihood for developing an appropriate rehabilitation design across the vast 70 km2 open cut coal mine forms the basis for this paper.
Keywords: open cut coal mine rehabilitation, spontaneous combustion, closure risk management
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