Application of Roof Pre-fracturing Blasting Technology during Initial Mining in Fully-Mechanized Face

With regards to problem that hard roof is not easy breaking down and top coal recovery during initial mining on fully-mechanized face in Changchun Coal Mine's,it adopted pre-cracking blasting technique on S6-2 fully-mechanized face,and it analyzed and summarized pre-cracking efficiency.The results indicate that first weighting pace of main roof reduced from 37.8 m to 13 m after roof pre-cracking,pressure strength was not markedly changed,however,continuous cycle was evidently reduced;the technique simultaneously solved the roof coal recycling well.In this experiment,more than 9 399 t coal was recovered because of 15 m early caving.