Patent GB-498538-A (GB)
Title: A method of treating waste materials to render the same more suitable for incineration and plant for carrying out said method
IPC: B03B9/06
Filed: 1937-09-14
Abstract: 498,538. Treating refuse and other waste materials. PETERSEN, K. Sept. 14, 1937, No. 25014. Convention date, Sept. 18, 1936. [Classes 59 and 117] [Also in Group I] Waste materials including household refuse, and horticultural and agricultural refuse, street sweepings, industrial refuse, &c. are crushed or ground with simultaneous and/or subsequent sorting or sifting to remove metal and other articles which cannot be ground and subjected to pneumatic separation to separate the heavy inorganic components. The grinding may be effected in ball mills in one or more stages, the material being reduced to pass through a sieve of about 0'6 inch mesh. In one form, Fig. 1, the refuse material passes to a slightly inclined ball mill 10 divided into sections 12, 14, 16 which are separated by screens 18, 20, 22 which retain in the sections grinding bodies 24 which are of decreasing size from section to section. The lower end 30 of the drum is displaceable to allow the size of the openings 32 through which the material is discharged to be varied. The ground material passes to a jig screen 36 reciprocated at high speed by crank gear 38, the sifted material falling into a separating chamber where it meets a strong air blast from a blower 44, the inorganic material being of higher specific gravity, falling into a chamber 42, the organic material being carried into chamber 46 from which the air escapes through openings 48. The material which does not pass through screen 36 is taken by a conveyer 50 and a bucket elevator 52 back to the mill 10. The material may be dried in mill 10 by air drawn in by suction or by waste gases from the incinerator. In a modification, Fig. 2, the refuse passes down a shoot 60 over an opening 62 over which it normally passes without dropping through, and a blower 64 above the opening 62 causes the lighter components to be blown through the opening beneath which they settle in a heap 66, the blower 64 may be replaced by an exhaust 70 which draws the material through the opening 62 into a chamber beneath the shoot 60, or a closed shoot may be used and the exhaust 70 replaced by a blower, the opening in the shoot being arranged to allow all the material to fall through normally, but the air blast from the blower causing the lighter portions of the refuse to float over this opening and pass on down the shoot. In a further form, Fig. 4, the closed shoot has a series of openings through which all the material is adapted to fall, but the lighter portion is caused to pass on down the shoot by an air blast from a blower 90, the heavy inorganic material being separated into grades of increasing fineness which are collected in three silos 82, 84, 86 disposed below the openings, the silos being interconnected by openings 92 and the air pressure regulated by valves 94. A separate blower may, in a further form, be provided for each silo. In all these cases, the blowers may be supplied with heated air or hot combustion gases for simultaneously drying the material. The organic material recovered may be passed to an incinerator directly or after being dried and this may be of simpler design than usual. The heavy inorganic portion may be sterilized by hot gases from the incinerator.