Blast design for improved performance and reduced surface vibration - a case study

摘要

Deeper level iron ore mining at a depth below 800-1,000 m in Western Siberia faces poor ground conditions and heavily complicated geomechanical conditions. Ore extraction involves such systems as level caving, room-and-pillar mining with and without backfilling and sublevel caving. Blast designs involve closely spaced rings ofblastholes with a diameter from 89 to 250 mm. Aiming to evaluate drilling-and-blasting parameters, researches have been undertaken to assess effects of blast patterns on quality of rock fragmentation by explosive charges and on rates of dynamic and seismic events. It is found that room-and-pillar mining with and without backfilling with different design factors allows enhancing efficiency and safety of stoping. The author has proposed a blasting technique and a method to determine powder factor per each blasthole with regard to geotechnical conditions in a mine.The application of the designed blast patterns enables reduction in powder factor by 20-30%, decreases yield of oversize by 15-20%, lowers amplitudes of the stope floor and ground surface vibrations and reduces seismic energy from 10~6 to 10~4 J.