Abstract: In order to solve the problem of excavating thin coal seam beneath under the condition of casting blast and dragline stripping technology at the bottom of the surface coal mine, the surface pillar mining has been proposed according to working features of stripping technology. The stripping ratio formula of thin coal seam has been deduced, and the optimum ratio of rock height to coal height has been determined, the requirement to work line of the surface pillar mining has been analyzed as well. After analyzing excavating parameters of the pillar mining technology and its application in the 9th coal seam of Heidaigou surface coal mine, the results show that more than 372 thousand tons can be excavated during the working line is 2 200 m, and it can bring 61.28 million RMB. Meanwhile, the approach has a great influence on capacity, and part-length of 9th working line should be discarded when the 6th coal is extracted to the end-slope with considering production capacity requirement and the 9th coal resource recovery.

Key words: surface mining, casting blast, thin coal seam, pillar mining technology