In layered blasting with bunch-holes equivalent spherical charge(ESC),the layered height is the height of a single crater,and plenty of blasting are required in the same blasting hole,which can cause problems such as uneven stope roof and hole collapse.This paper is based on the theory of bunch-holes blasting and determines the parameters of crater blasting through on-site experiments,and the sublevel mining with double craters blasting of bunch-holes(BDC)is developed.It arranges ESC craters in two layers.These charge packs are detonated simultaneously,and the blasting directions point towards the drilling chamber in the upper part and the free face in the lower part in the stope,forming a combined blasting craters for the segmented ore caving.The segmented height is the sum of the crater depths and the spacing distance of the two craters,and its height is 14～20 m.The blasting scale is about 100 000 t,and the recovery rate≥85％,the dilution rate≤10％,the block rate＜5％,the production rate≥2 500 t/d.The method solves the problem of borehole damage during the blasting process and increases the scale of a single blasting in the mining area,greatly improving mining efficiency.
bunch-holesequivalent spherical charge(ESC)combined blasting of double craterssublevel mining method
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