Blasting techniques and explosives in the German quarry industry

摘要

Regulations concerning blasting immission protection, for example vibration protection as defined by DIN 4150 (DIN = Deutsche Industrienorm ~ German Industry Standard code) and the considerable associated regulations regarding blasting of greater bench heights have influenced the development of blasting techniques and explosives up until now. The blasting regulations have an even greater impact during the initiation of borehole columns greater than 12 meters in length. These considerable bench heights in conjunction with deviations from drilling accuracy often lead to oversized burdens and an unfavourable proportion of burden and spacing. These factors result in the loss of energy during the detonation of charges within the borehole and typically necessitate the need for additional lifter holes in the bench operation. In the past the small amount of electrical delay periods limited the possibilities for minimizing blast vibration which handicapped the reduction of output frequencies during blasting. Changes in the blasting regulations in 1995 along with special regulations regarding initiation using detonating cord facilitated the introduction of new initiation and blasting techniques. The new regulations permitted the evaluation of new initiation systems and blasting techniques like non-electric detonators, deck blasting, initiation from the bottom of the borehole, initiation using boosters, etc. The regulation necessitating the use of detonating cord down the entire length of the blast column curtailed the development of explosives that reacted marginally to detonating cord initiation. The effect from the detonating cord regulation resulted in the near exclusive use of cap-sensitive explosives and had a significant adverse impact on the use of bulk emulsion explosives. The newer regulations permitting initiation without detonating cord down the borehole is promoting the use of booster sensitive explosives and initiation from the bottom of the borehole. Today, up to one third of the total explosives used in Germany are delivered by mobile mixing and loading vehicles. The amount of bulk explosives continues to increase. Blasting development is promoting the increased use of mobile delivery units for ANFO and emulsions. The use of smaller sized vehicles for delivery is leading towards a more universal use of bulk explosives in the German market.