Laserfiche WebLink
Each of the mines are developed around a set of <br /> main entries consisting of from S to 7 headings that are driven <br /> downdip more or less perpendicular to the strike. Development <br /> headings are driven on the strike at approximately right angles <br /> to the main entries at intervals determined by the mining method <br /> and the geology. Development headings extend for distances up to <br /> 10, 000 feet . After completion of development headings, secondary <br /> mining is initiated and the pillars are mined out in an orderly <br /> retreat fashion (pillar section) back to the barrier pillar that <br /> is left adjacent to the main entries, and then the pillared area <br /> is sealed . <br /> Two longwall mining methods have been employed in <br /> Coal Basin. They are similar except that in one configuration <br /> the longwall face "advances" away from the main slopes without <br /> development workings ahead of the face, while in the other it <br /> "retreats" toward the main entries along predeveloped headings. <br /> Other essential underground activities that take <br /> place concurrently with the actual cutting and removal of the <br /> coal are ventilation, roof control, dust supression, water <br /> control, and equipment maintenance. Underground mining opera- <br /> tions are inspected regularly by the Mine Safety and Health <br /> Administration, the Bureau of Land Management (Branch of Solid <br /> Minerals) and the Colorado Division of Mines . <br /> Mined coal is transported on conveyor belts to the <br /> surface where it is placed in temporary storage bins at the mine <br /> portals . Immediately prior to being placed in the bins the coal <br />