Some underground coal mining regulations specifically prohibit the use of light alloys (e.g. aluminum) underground and in the fabrication of mine fans. Although the federal regulations do not prohibit the use of light alloys, it is normal practice that light alloys are limited for use in underground coal mines. This is due to the potential hazard of methane ignitions when light alloys strike against rusted steels. Research in this area was principally undertaken in Great Britain and Germany and had shown that the incendivity of light alloys impacting on rusted steel apparently involves a thermite reaction which is hot enough to ignite a methane-air mixture.
The U.S. does not prohibit the use of light alloys in underground coal mines and consequently much of the equipment manufactured in the U.S. has components comprised of light alloys. This is done to reduce weight and overall costs. An increasing amount of equipment purchased for the Canadian underground coal mining industry comes from the U.S. In order to meet Canadian regulatory requirements for the use of this equipment underground, potentially expensive modifications have to be made to replace the light alloys and in addition this ties the equipment up while the modifications are being made.
A project was undertaken to look at the scientific basis for which light alloys are prohibited from use in Canadian underground coal mines and possible remedial actions where light alloys could be used and not be a potential hazard. The use of foils or pop cans was also investigated. This project has been completed and a fact sheet has been prepared outlining the hazards of light alloys. The fact sheet has been made available to the underground coal mining industry and is available on this web site in both html and pdf formats. Laminated copies are also available from G. Bonnell. (See "General Inquiries" for contact information).
A copy of the fact sheet is available under "Fact Sheets" or else click here.
Light Alloys [PDF]