Method and application of overcoming the great resistance line in high bench blasting of open pit mining

With regard to the great resistance line problem in high bench blasting of open pit mining, it is presented the method which combined the joint operation of drilling equipment with the blasting technique of big pitch and small array pitch.That is the layout chart of the drill hole based on the joint operation of the rotary drill rig and in-the-hole drill.The bore diameter of rotary drill rig is 310 mm, and the bore diameter of the in-the-hole drill is 165 mm.The arrangement is to add three inclined holes of 165 mm between two 310 mm vertical holes in the front row, and the inclined holes parallel to the bench slope.The blasting technique adopts the big pitch and small array pitch.According to this method, the design of high bench blasting is carried out.The blasting effect is good in the field.The blasting muckpile is neatly stacked.And there are no big blocks and no roots in the blasting muckpile.The results show that this method not only can effectively solve the problem of great resistance line, but also can guarantee the drilling efficiency to the most extent and make blasting economical and rational.