Variable wall mining machine. Third quarterly technical report, April 1, 1994--June 30, 1994

摘要

This is the Third Technical Report to develop the Variable Wall Mining Machine(VWM), a patented mining system that has the potential of greatly improving the underground mining of coal and other flat-lying mineral beds by providing a greater safety for workers, a healthier human environment, and a higher productivity. One of the thrusts of this project is to analyze the adaptation of the VWM system to a dual duct ventilation system which separates the air for human breathing from the air which becomes contaminated from dust and dangerous gases. In conventional practice there is one zone in an underground working section where workers breathe the air used to carry away gases and dust. A proposed dual duct system divides the single zone into two zones: one for cutting and fragmentation and one for worker occupancy. It is both technically and economically impossible to ventilate longwall face with the conventional method when methane emission rate is higher than 1,500 cfM. The only available option to the methane problem is to pre-drain the methane before mining so the methane emission rate will be lower later during longwall mining. But it is questionable that enough methane can be predrained to significantly erase the explosibility problem. Contrariwise, the dual-duct gas control method requires significantly less ventilating air, resulting in large savings in fans, air course construction, and energy. The overall costs are measurably less. Since the cutting chamber is sealed, the dust and methane are extracted from the mine in a separate ventilation system at a speed which is independent of the general mine ventilation system.