NO752962L

1513041 Impact pulverizers, comminuting at low temperatures VEREINIGTE ALUMINIUM-WERKE AG 21 Aug 1975 [5 Sept 1974] 34824/75 Heading B2A Scrap material and particular material with a plastics or rubber-to-metal boro e.g. bottle caps, is comminuted in an apparatus comprising a charging vessel 1 fed via a hopper 9 with a screen 10 and a pneumatic conveyor 11, delivering material via a metering feeder 3 and metering funnel 2 to a beater mill 13. The material in vessel 1 is refrigerated with liquid nitrogen the temperature being sensed by a thermometer 17 and charging level which determines onset of refrigeration by a photo-electric device 24. When the temperature and level are correct the feeder 3 delivers the embrittled material to the mill. The components are separated in a rotary separator 4. The P.V.C. or rubber fragments are collected in a funnel 9 and the bottle caps are discharged into a bin 5. The thermometer 17 is associated with a two-portion proportional controller which permits temperature progressively to approach a reference temperature by control of a liquid nitrogen valve 16 which supplies an atomising nozzle 15. A fan 21 draws nitrogen from the top of vessel 1 and thus maintains a slight vacuum in the vessel.