Safety heating elements for initiating non-detonating thermal decomposition of blasting charges

摘要

731,096. Blasting cartridges and charges. IMPERIAL CHEMICAL INDUSTRIES, Ltd. Nov. 18, 1953 [Jan. 14, 1953], No. 1089/53. Class 9(1). The fluid-pressure blasting cartridge 1 shown in Fig. 1 contains a gas-producing charge 5 and heating means 7 for initiating thermal decomposition of the charge, the heating means being an electric initiating element 8 and a heating composition 9 comprising 66.0-45.0 per cent by weight of guanidine nitrate, 27.0-45.0 per cent by weight of potassium persulphate and 6.0- 10.0 per cent by weight cuprous chloride. Up to 1 per cent by weight of petroleum jelly may be incorporated. A preferred composition comprises 60 per cent .guanidine nitrate, 31.5 per cent potassium persulphate, 8 per cent cuprous chloride and 0.5 per cent petroleum jelly. The charge 5 may be enclosed in a container 6, which may be of sheet metal, synthetic resin or fireproofed cardboard and closed at one end by a wooden plug and at the other by a cork, which is blown out on rise of pressure in the container. The charge 5 may be a pulverulent mixture of 49.2 per cent magnesium nitrate hexahydrate, 38.8 per cent ammonium nitrate and 12 per cent wood flour. An alternative charge, unconfined in the cartridge, is an equimolecular mixture of sodium nitrite and ammonium chloride with 3 per cent of magnesium oxide. Specification 724,060 is referred to.