Formation of boulder and blast technology in the limestone open pits

Based on the analysis of causes on which the blasting boulder occurs in borehole blasting of the limestone open pit,the paper determined some measures of lowering boulder yield of borehole blasting operation in the limestone mining open pits by borehole parameters,taking explosive specific charge,charge structure,millisecond interval and detonating into design of blasting program.The blasting with the controlling measures resulted in very satisfied effects in practice.