Blasting off-the-solid (BOS) - a new approach

摘要

Increasing average powder factor and total pull under blasting off-the-solid (BOS) are the prime necessities of the coal mining industry because of the stagnating production in BOS during the last three decades from underground coal mining.While maximum charge of 1000 g per shot hole has so far been allowed by the DGMS in degree I coal mines, only 565 g is allowed for solid blasting in higher degree gassy mines.Renovation in the technology of blasting either by enhancing charge limit per shot hole or bringing some change in the usual firing pattern of blasting-off-the-solid in underground coal mines may be two options for increasing average pull and powder factor i.e. overall productivity of the underground coal mines.Experiments in the laboratory conditions for ascertaining safe maximum charge weight of P_5 explosive have indicated scope of using higher charge without impairing safety parameters to optimize production from BOS. Further studies of AGS of permitted explosive in varying laboratory conditions and coal bed confinement have shown encouraging results. Observed enhancement in AGS values of permitted explosive cartridges with increasing confinement/coal bed confinement open up the scope of use of air deck technique with plastic spacers in between the cartridges for improvement of powder factor.The authors have presented their concepts and analysed experimental data generated so far, which may be of interest to all concerned from the safety and productivity points of view. Need for more studies in these directions has been suggested to corroborate the observed results and extrapolate them for the benefit of the Indian mining industry.