Scoping Study: Application of New Forms of Fire Suppression and Hydrocarbon Absorption Materials to Underground Coal Mines

This project was undertaken at the request of the underground research committee in response to some reports of alternative forms of fire suppression and gaseous hydrocarbon encapsulation. The project examined the potential application of these products and methods to the underground coal mining industry.

Traditional methods of controlling large scale fires in underground coal mines resulting from gas and coal dust ignitions and spontaneous combustion are limited generally either because of the dangers of explosion and/or the inaccessibility of the fire. In almost all cases of recovery from an ignition or a heating, the main methods of control are based upon some form of inertisation either by the sealing off the affected area, perhaps the whole mine, and allowing the fire to self-extinguish, or by introducing large volumes of inert gas to displace air. Examples of the latter are the Gag jet engine, Tomlinson boilers, cryogenic nitrogen and Floxall pressure swing systems. All involve specialized equipment with long deployment times unless pre-arranged, and may not be able to be deployed close to the location of the fire.

There are a number of "new" firefighting/suppression products that have come available which may offer advantages over traditional firefighting products or potential improvements or process changes that the coal industry could take advantage of. Examples of new products are micelle encapsulation chemicals, and superabsorbent water holding gels. There may also be "old" firefighting/suppression products and methods such as hydrofluorocarbons (HFCs) that have not been considered for application in the coal mining industry but which could be advantageous. Each chemical offers improvements in the ability to extinguish certain classes of fire.

There are sometimes properties that might also be applied to controlling other hazards such as the ability of the micelle chemicals to encapsulate hydrocarbons which has found application in vapour suppression and absorption in enclosed spaces such as aircraft fuel tanks. These materials were developed largely for the purposes of fire suppression by improving the wetting characteristics of water but also have the ability to absorb gaseous and liquid hydrocarbons thereby removing them as potential fuel sources in a fire. It has been suggested this could have application to reducing the levels of methane in gassy coal mines. This property of micelle chemicals may be of the most benefit to the coal industry exceeding that of improvements in fire fighting ability, and warrants investigation.

It should be noted that information provided to the author from the underground committee referred to two specific products, namely F500 marketed in the USA by Hazard Control Technologies and Khladon as apparently used in a recent explosion at a Russian mine "to neutralize methane". From investigation so far it is clear that F500 falls into the category of micelle technology and has demonstrated capabilities in improved fire suppression compared to water and works partly by absorption of hydrocarbons. It is used for degassing enclosed spaces and has been demonstrated to coal and other industry representatives in the USA. Kladon is the Russian tradename for a chlorofluorcarbon product similar to that known as Freon. It is not clear what specific form of Khladon was involved in the Russian mine explosion. There are many variations of chlorofluorocarbons many of which are now banned under the Montreal Protocol of 1987. There are no hydrocarbon adsorption properties associated with chlorofluorocarbons which work by displacement of air and by heat adsorption.