Underground » Detection and Prevention of Fires and Explosions
The many inherent hazards in underground coal mines often have complex interactions that require careful balance in order to provide a safe and productive work environment. This is no more evident than in and around a longwall panel where spontaneous combustion, gas management and the environment including heat and respirable dust management can be in conflict with each other.
The risk posed by spontaneous combustion continues to have the potential of extreme consequence to both whole mines and their workers. The frequency is much higher than the industry would consider acceptable which demands action to further manage the hazard.
There has been extensive and ongoing research into the understanding of the chemistry of coal oxidation and the factors that increase its propensity to self-heat. Additionally, the gas and air flow dynamics around longwall circuits has been investigated using CFD modelling and tracer gas survey which has provided insight into how oxygen penetrates deep into goafs increasing the size of the risk area. Proactive inertisation of the goaf has been proposed using low flow inert gas injection. Fire retardant foams can assist preventing the inert gas dispersing and can assist maximise the effectiveness of the inertisation process.
The research undertaken in this project, and previously in C12020 and C15020, has studied the causal factors influencing the spontaneous combustion hazard and has trialled inert gas injection including using and developing high expansion firefighting foams to assist its effectiveness as a proactive risk reduction strategy.
A purpose designed foam and injection system has been established in Germany specifically for the underground coal industry. The primary objective of this project was to import a full system ready for deployment in Australia.
This has been achieved with the system now fully maintained by NSW Mines Rescue Service. The MINING 12000 system by One Seven is designed to permanently hang off a longwall monorail or is readily transportable around the mine. The system can produce up to 12000 litres of foam per minute. The One Seven AM foam concentrate is a Class A fire extinguishing surfactant agent for solid fuels and was developed for application in underground coal mines (A for Class A, M for Mining).
The foaming agent is biodegradable and fluorine free. The MINING 12000 systems main differentiator is that it is compact and can be deployed from underground, significantly improving the flexibility of application and providing mining practitioners with simple to operate, early mitigation strategies that have otherwise not been available. The machine has no electrical components and proportions the mixtures of compressed air/nitrogen, water and foaming agent such that a range of foam consistencies are produced from wet slurries to dry shaving cream consistency for different applications.