| http://www.w3.org/ns/prov#value | - In operation, air, preferably preheated as noted above, e.g. to a temperature to about 1400??? F, is first injected via line 20 into the bore holes 14, and the coal 46 surrounding the bore holes 14 at one end 47 thereof adjacent the air inlet and manifold 16, viewing FIG. 2, is set afire either due to the heat of the injected air or oxygen, or by special external means such as a formation-lighting
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