| 摘要 |
1534506 Comminuting at low temperatures BOC INTERNATIONAL Ltd 14 Nov 1975 [15 Nov 1974] 49411/74 Heading B2A Scrap e.g. metal, rubber, or plastics is comminuted by cooling in a closed insulated chamber to the embrittlement temperature by use of a cryogenic liquid or cold gas, after which comminution is effected whilst the scrap is at least partially brittle. The scrap, as described, may be a mixed pile with magnetic separation following comminution or it may be presorted into primarily ferrous and primarily non-ferrous scrap. A system of metering with a valve 46 Fig. 3 a temperature-control solenoid-valve 42 and a time-control solenoid-valve 48 permit injection of liquid nitrogen in a chamber 30 at chosen time intervals and cools scrap in skips within the chamber 30 over a prolonged period without waste. In a second embodiment Fig. 4, not shown, liquid nitrogen is injected continuously until the temperature has fallen sufficiently. Fans equalize the temperature throughout the chamber. |
