NO DYNAMITE NEEDED: A new rock blasting technique which does not require explosives has been developed in Sweden - too late, in a way. Because if Swedish inventor Karl Gustav Derman had pipped Alfred Nobel, the inventor of dynamite, to the post, we might still be fighting wars with bows and arrows. But then, of course, Bofors would never have been able to sell armaments.
"The new method is based on hydraulic pressure", says Derman. "Oil is pumped into a specifically designed expanding cartridge and placed in a bore hole in the rock. Up to 80 per cent of all rocks crack before or at a pressure of 700 bar, but particularly solid or stubborn boulders may require additional cartridges."
The patented method, dubbed Dermanite, is marketed by Westboenergi in Anderstorp, southern Sweden. The company recommends the technique for farmers wanting to remove boulders from their land, for house owners wanting to remove a rock too close to the house - careful! - or for road workers who have to eliminate a road-side rock while traffic continues to flow.
The expanding cartridge comes in three sizes, The standard 30cm unit develops an "explosive force" of 60 tons with the lowest pump-power force and up to 125 tons with the highest pump force. The cost of the standard unit with three expanders is estimated at about SEK 12,750.*
EX - The Magazine for Nordic Airport Passangers March/April 1992
* about £1300.