Abstract: Karst may lead to a leakage of blast energy, seriously affecting the rock fragmentation and blasting effect. Adjacent borehole explosion may cause a large area of misfire due to sympathetic detonation. In case of ignition in borehole sequence, each blast hole has three or more free faces, which will facilitate the rock throw-out and the ignition of adjacent blast holes at different times can avoid the occurrence of stress reduction area. The key of the technique of blasting ignition in borehole sequence lies in credible precision detonator system, rational millisecond between bore to bore and row to row and correct blasting network design. The test of ignition in borehole sequence carried out at a karst developed limestone quarry has proven that this technique can improve the blasting effect, evidently reduce the blasting caused vibration, decrease the comprehensive production cost of mine and effectively prevent a large area of misfire and improve the mine safe operation level.

Key words: Karst, Limestone quarry, Ignition in borehole sequence, Misfire, Test research