They’re not that bad in general C-H. You are battling with Mother Nature with very deep mines nearly 4000m down (13000 ft for the metrically challenged). With the natural heat flow from the earth, at these depths the virgin rock temperatures can be in excess of 50C. Out of necessity, South African mining companies pioneered mining refrigeration with massive fridge plans both on surface and underground. South Africans also pioneered earth leakage protection devices too – just to keep it electrical
. These fridge plants chill huge quantities of water and consume an enormous amount of power. With the hoists, fans, fridge plants, compressors, lights and equipment each of these mines consumes a small town’s worth of power and its recent massive price increases has been a major concern for the mining houses down there as after labour, it is the next greatest input cost.
As well as cooling the air down with heat exchangers, the chilled water (nearly freezing) is used directly in the air-powered rock drills (as the lubricant) and keeps the working place comfortably cool. It is away from the working ends in places with less than adequate ventilation that problems can occur. If there’s no ventilation, you’re not supposed to go there. Somehow though, many geological problems always seemed to be somewhere that someone had cut the juice to the fans – or simply relocated the fan.
[edited for clarity]
[This message has been edited by Hutch (edited 01-04-2004).]