Gas Control and Fire Prevention and Control Technology During Equipments Withdrawing Period in High Gassy and Easy Spontaneous Combustion Fully-Mechanized Top Coal Caving Mining Face

Under the condition of high gassy and easy spontaneous combustion ultra thick seam, the fully-mechanized top coal caving mining face would have two big problems of the gas control and the spontaneous combustion prevention and control at the same time. Taking Dafosi Mine as a case, the paper analyzed the factors affected to the gas control and the spontaneous combustion prevention and control, and the mutual influence between the two. With the comprehensive adjustment of th e applied ventilation system, gas drainage, coal left reduced in the goaf, inhibition and inerting enhanced in the goaf, air leakage reduced in the goaf, gas monitoring an d measuring enhanced in the goaf, withdrawing speed of the coal mining face speeded up and other means, the gas volume fraction of the coal mining face and the air return gateway was not over 0. 8% during the equipment withdrawing period and the CO volume fraction at the monitoring and measuring points was not over 50 x 10- 6. Those effectively could meet the requirements of the gas control and the fire prevention and control, and ensure the safety equipment withdrawing from the fully-mec hanized top coal caving mining face under the complicated conditions.