Abstract: Sublevel stoping method with medium-depth hole blasting has been widely used in the mining of medium-thickness or thicker orebody at home and abroad. With the Large-scale development of drilling equipment, the sublevel height in the sublevel stoping method is gradually increasing, which can reduce the mine development amount and improve the production capacity, but simultaneously result in difficulty in controlling mining loss and dilution from drilling deviation and affect mine economic benefit directly. In the paper, taking a high-level sublevel stope of a metal mine in Tibet for example, the test parameters of medium-depth hole blasting are determined comprehensively by investigating the designing principle of medium-depth hole blasting parameters and the blasting design parameters of medium-depth hole stope being implemented at home and abroad, and considering the factors such as the deviation of drilling rig caused by high sublevel. Through the repeated blasting tests and the parameters optimization in production process, the suitable medium-depth hole blasting parameters for ore-rock features of stage-2 underground mining area in this mine. Such indicators as the block rate of 4.75%, the mining loss rate of 7.34%, and the dilution rate of 3.28% have been obtained in the end. It can provide technical reference for the efficient blasting of medium and deep holes in the stage-2 underground stope.

Key words: Medium-depth hole blasting, High sublevel stope, Blasting design, Blasting effect, Parameter optimization