Optimization On Blasting Parameter In Beiminghe Iron Ore Mine

Beiminghe iron ore mine is contact metasomatic skarn polymeatal deposit, its mining method is non-pillar sublevel caving. The thick ore bodies of the mine have been mining. The sublevel height is fifteen meter, the drift interval is eighteen meter, the caving space is one point seven to three point seven,the ignition sequence is bottom priming in same stage. There are several problems in produce such as the borehole was blocked or deformation, the high big rock rate, the partition and goal suspended ceiling appeared which impact recovery index and mining efficiency seriously.This paper systematic study of initiation sequence, blasting parameters and deter-mining hole intervals based on the blasting mechanism of fan-patterned holes. The paper discussed that the initiation sequence and the explosive azimuth had effect on rock breaking efficiency and determined the model of hole-bottom millisecond initiation according to the mechanism of shock wave and detonation gas rock breaking together and the data in domestic literature. According to the shapes of draw body and residual body and the date of waste in-ore rate calibrated in ore removal, it deduced the shape of caved ore body. It proved that the shapes of draw body, residual body and caved ore body when the caving space is 1.7 meter coincided poor with each other in existing structure of the stope which is the main reason of sooner and higher waste in-ore rate. Comparing the condition when the caving space are 3.4 meter and 3.7 meter,it found that the ore increasing rate in the lower part of draw body is higher than the waste increasing rate in the upper of the draw body,so the caving space of 3.7 meter is superior to the caving space of 3.4 meter in existing structure of the stope. The paper designs the blasting network that it blasted two rows boreholes, the front row arrangements nine boreholes whose resistance line is two meter. The back row arrangements eight boreholes whose resistance line is one point seven meter. The hole-bottom spacing has increased from two point six to three point six, and the borehole has decreased by one ore two in improved blasting network, which can save 92.7 kilogram explosive and 20.6 meter boreholes in each caving space.The improvement scheme has submitted to the mine, and has been reviewed and implementing.