GB643871A - Improvements in or relating to ammonium nitrate blasting cartridges - Google Patents

Abstract

643,871. Blasting cartridges; explosive compositions. ATLAS POWDER CO. July 21, 1947, No. 19450. Convention date, Nov. 16, 1943. [Classes 9 (i) and 9 (ii)] A blasting cartridge for use underwater comprises a waterpervious case 11 filled with a water-absorptive ammoniun nitrate explosive composition 13 which includes a sensitizer and having a waterproof high explosive core 17. The case 11 is of paper crimped over at the ends and the ammonium nitrate is sensitized with nitroglycerine. The high explosive core 17 is a paper-wrappec charge of gelatinized nitroglycerine dynamite. The core may extend only part-way through the cartridge and its diameter may be varied to alter the longitudinal velocity of detonation of the cartridge. This velocity may also be varied by using different types of dynamite for the core, such as ordinary nitro-glycerine dynamite in a water-proof container or electro-plated TNT. The cross-sectional area of the core is between 3 per cent and 15 per cent of that of the cartridge. Sensitizers of ammonium nitrate given are nitro compounds, such as dinitrotoluene, trinitrotoluene, cyclonite, nitric esters, such as nitro-glycerine, nitro-glycol and nitro-sugars, and metal powders, such as aluminium dust. The amount of sensitizer in the ammonium nitrate may be between 4 per cent and 20 per cent by weight of the nitrate. To initiate the cartridge when wet a detonator or detonating fuze may be inserted into the core or a quantity of gelatine dynamite containing a detonator may be placed in the bore-hole adjacent the core. Preferably water present in the ammonium nitrate exceeds 6 per cent of its weight. The water may be poured into the borehole after the cartridge is placed in position. In an example, paper cases of 6 in. diameter were filled with ammonium nitrate explosive around a 1“ in. diameter core. The cartridge was 24 in. long and weighed 25 lb. The ammonium nitrate explosive consisted of ammonium nitrate 81 per cent, nitroglycerine 6 per cent, sulphur 4¢ per cent, sodium nitrate ¢ per cent, chalk per cent, carbonaceous ingredients 7¢ per cent, all percentages being by weight. The cartridge was initiated underwater by firing an electric blasting cap placed in gelatine dynamite against the cartridge. An alternative cartridge contained 44.8 per cent ammonium nitrate and the sulphur was omitted.