Hello I worked for National Mines Service Company for 18 years before they were sold and moved from Ashland Ky. We built a lot of underground equipment for coal mines. The equipment for Canada mines were for Potash Mines they were diesel shuttle cars or the 3 or 4 Rotors Marietta Miners. The 4 Rotor would mine 17 tons of Potash in 1 minute. These mines are very large in size once something would go down it would stay there. Knowing that we never built equipment for coal mines in Canada I checked it out there is only 4 underground coal mines in Canada, two of them are on Cape Breton Island under the sea at 1000 meters below sea level. They use a lot of Longwall shears. They drill holes in the roof's of the mines and extract methane gas to make it safe. Canada does produce a lot of coal by strip mining a pit mining. Max Cartwright