Key technology for fully-mechanized top coal caving with large mining height in extra-thick coal seam.

Fully-mechanized top coal caving with large mining height is the main mining method for extra-thick coal seam. However, as the height of coal cutting and coal caving increases, prominent problems such as severe mine pressure behaviour severe rib spalling in working face, low top coal recovery rate and high gas emission rate and so on emerge. Based on the analysis of the development history of the fully-mechanized top coal caving in China, taking the working face 8105 at Tashan Coal Mine as the engineering background, authors studied the movement characteristics of the top coal and roof at the fully-mechanized top coal caving face with large mining height in the 14-20 m extra-thick coal seam, successfully developed key technologies such as the comprehensive prevention and control technology for rib spalling at the fully-mechanized top coal caving face with large mining height, high-efficient coal caving technology with high recovery rate and safety guarantee technology for mining under the condition of "low gas occurrence, high gas emission", etc. The underground test showed that the recovery rate at the fully-mechanized top coal caving face with large mining height 8105 at Tashan Coal Mine reaches 88. 9% which is 5.9% higher than that at working face 8104, the average operating rate of the equipment at the working face reach 92.1 %, and the raw coal produced at the face in 2011 reach 10.849 Mt, which achieve the objective of 10 Mt coal produced at the fully-mechanized top coal caving face with large mining height using domestic equipment in a year. [ABSTRACT FROM AUTHOR]