The blasting technology and practice of one-time recovery of double top pillars and columns

The pillars account for 30% of the ore content of the mine house in empty field mining method.Reasonably and efficiently recovering the ore pillars has a significant impact on resource recovery and mine economic benefits.Taking the 850 m middle pillar group of Dongshengmiao lead-zinc mine as the research object, the overall recovery plan for interval extraction is finally determined by analyzing the distribution of the pillar group and the actual situation on the site.Through the comparative analysis, it is determined that No.16 pillar is the first mining pillar, and the medium-deep hole and deep-hole combined blasting technology are adopted.The No.16 pillar and the top pillars on both sides are recovered at one time.The millisecond blasting technology is adopted.The free surface detonates first, and the top column uses the lower free area to initiate the detonation.Due to the large area of the top column, a partitioned millisecond blasting technique is used to form a multi-faceted open-space three-dimensional controlled blasting technique, making full use of the existing empty areas and forming multiple differential blasting technologies for combination and different blast apertures.Statistical calculations are performed on the recovery indicators.Both the depletion rate and the loss rate are controlled at 30%, and the amount of once-recovery ore is 87 509 t.