Explosives . nt in the finished mill-cake, for larger sizes 3 to 6 per cent. In France mills similar to the Gruson mill are used, but the charge is only2o ktr. or 2.) kg. in the case of mining powder. It contains 8 per cent, moisturewhen introduced and 2 to 4 per cent, at the finish. The mill makes 10 revo- 1_Vennin ct Ch-csneau, p. 333. MANUFACTURE OF GUNPOWDER 79 lutions per minute and requires 7 horse-power. The following table givesthe times of milling and the densities of the mill cake : Time Density Military rifle powder, F3Sporting powder, ordinary ,, ,, strongDust reworked ....Mining p
Explosives . nt in the finished mill-cake, for larger sizes 3 to 6 per cent. In France mills similar to the Gruson mill are used, but the charge is only2o ktr. or 2.) kg. in the case of mining powder. It contains 8 per cent, moisturewhen introduced and 2 to 4 per cent, at the finish. The mill makes 10 revo- 1_Vennin ct Ch-csneau, p. 333. MANUFACTURE OF GUNPOWDER 79 lutions per minute and requires 7 horse-power. The following table givesthe times of milling and the densities of the mill cake : Time Density Military rifle powder, F3Sporting powder, ordinary ,, ,, strongDust reworked ....Mining powder .... 2 - . H 5 i • i M hours 1-7401-7251-80 1-57 The density is of importance because in France the powder is not density can be increased by milling slowly, half a turn per minute, withthe outer plough In Germany the charge is generally about 75 kg. and the mill makes aboutnine revolutions per minute. The time of milling is : Military powderSporting „Mining ,, 2J-3 hoursH 0=. Fig. 8. Drenching Arrangements for Powder Mills. Before the charge is removed the mill is run slowly for a time to increase thedensity, but the powder undergoes a pressing operation also, except in the caseof mining In order to prevent the explosion in one mill being communicated to the Automaticother mills of the group, each one is provided in England with an automatic drenchers-drenching arrangement (see Fig. 8). This consists of a lifting board /, providedwith a counterpoise weight. There is also a tank t full of water, supportedon a hinge and a leg at one end that rests on a projection from the liftingboard. When the latter is lifted, the leg is released, the tank tips forwardand the water is poured over the charge in the mill. The axle a is common 1 Vermin et Chesneau, p. 332. 2 Voigt, Herstellung der Sprengstoffe, pp. 56. 8o EXPLOSIVES Removing themill-cake. Breakingdown. Pressing.
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Keywords: ., bookcentury1900, bookdecade1910, bookidexp, booksubjectexplosives
