Proactive Inertisation Strategies and Technology Development

The frequency of heating incidents in longwall panels has increased significantly in recent years, leading to production losses and safety risks for a number of coal mines. Review of oxygen ingress patterns into longwall goaf at various mines has shown that in some cases the oxygen concentration in the goaf was well over 17% even at 300 m to 400 m behind the longwall face. Under those circumstances, the risk of the heating/spontaneous combustion incidents increases substantially during slow panel retreat or prolonged face stoppage periods. To reduce the risk of these goaf heatings, a major research project has been undertaken under the ACARP project 12020 “Proactive inertisation strategies and technology development”.

The main objective of the project was to develop and demonstrate the proactive and effective inertisation strategies and techniques to reduce the risk of spontaneous combustion and heatings in active longwall panel goafs. The project has combined extensive field studies, together with computational fluid dynamics (CFD) models of goaf gas flow, to develop proactive inertisation strategies. The project has developed a detailed understanding of the effects of various inertisation strategies on goaf gas distribution in longwall panels.

Field studies involving low flow inertisation of the working longwall panel goafs have also been conducted at two underground operations. The project results have shown that the proactive inertisation strategies implemented at the field sites were highly successful in reducing oxygen ingress into the goaf and the consequent risk of heatings in the longwall panels during the field demonstration periods. Results of various modelling investigations and field studies are presented in this report.