GB1422105A - Process and apparatus for mixing pulverizing and grinding black powder - Google Patents

Abstract

1422105 Jet pulverizers FLUID ENERGY PROCESSING & EQUIPMENT CO 17 May 1974 22025/74 Heading B2A [Also in Division C1] Black powder viz. potassium nitrate, charcoal and sulphur, with optional additives e.g. wood flour is made in a mill system comprising a pair of curved jet pulverizers 10, 100 in series, the first 10 having a high pressure jet feed and the second a low pressure jet feed, the first pulverizer having an expanded downstack 20 and the second pulverizer an expanded upstack 106. Both pulverizers are of the known "tractrix curved" type. A relative humidity of 85-95% is maintained by injection at 46, 48 of a fine spray mist of water (0.01 to 10 Á) with automatic metering. The water is preferably at 70‹ to 100‹C. Potassium nitrate is supplied from a hopper 40. The charcoal is cooled e.g. with liquid air or nitrogen via a pipe 38 to increase its absorptivity prior to its passage from a hopper 30 into the mill; and slowed down as it goes through the downstack 20 where the potassium nitrate dissolved in the hot water spray is absorbed and adsorbed. Alternatively a coolant solution may be used instead of water. Material is exhausted along a duct 18 to a cyclone 28. Clean gas is exhausted from a filter 52 via a duct 54. Dust and separated solids pass into a receiver 58 are dropped on to a conveyor 62, compacted by a compactor 64 and are disintegrated and sieved at 66. Additives, e.g. wood flour, may be introduced either with the charcoal and sulphur or via a separate feed inlet. The material is fed to the second mill for polishing via hopper 114. Graphite is supplied to the mill via a hopper 118. The widened upstack 106 permits rolling and tumbling of particles without excessive grinding. The product is exhausted via duct 112 into a cyclone 122 and is discharged into a container 130. Both mills and all other components are grounded and the nozzles may be of nylon to prevent electrostatic sparking. In a modification all components are added to the mill 10 above the expanded downstack portion 20.