Patent GB-1457041-A (GB)
Title: Recovery of salvageable components from waste material
IPC: B01D37/00
Filed: 1974-02-15
Abstract: 1457041 Recovering scrap aluminium BLACK CLAWSON FIBRECLAIM Inc 15 Feb 1974 [16 Feb 1973] 7118/74 Heading C7D [Also in Division B1 and B2] A method of recovering scrap aluminium from municipal waste comprises (a) depositing the waste with a liquid in a treating vessel; (b) subjecting the resulting suspension to combined forces of hydraulic and mechanical shear and mechanical impact to cause the frangible solids therein to be reduced to (i) flake-like particles of aluminium alloy (ii) other metal particles including pellets of aluminium foil (iii) particles of glass and other pulverulent inorganic materials, and (iv) fibre and other organic materials in particle form; (c) extracting the reduced materials of less than a pre-selected maximum particle size from the remainder of the suspension; (d) treating the extracted materials to separate the majority of the fibre and other organic materials from the other particles to leave a mass of said particles of aluminium alloy other metal, glass and other pulverulent inorganic materials; (e) subjecting the mass, optionally after removing some of its particles, to agitation to its cause the flake-like particles of aluminium alloy to migrate to, and be concentrated in, the top surface portion of the said mass; and (f) effecting removal of the concentrated particles of aluminium from alloy the remainder of the inorganic fraction by a skimming action. In the method illustrated, the waste is supplied to a vessel 10 to be treated by a rotor 11 in water supplied by a line 28 through a junk remover 21 which removes large infrangible solids to a sep-  arator which includes magnetic means for separating ferrous metals from the other solids and means for screening liquid and fines for recirculation to the vesse110. The rotor 11 includes flails or hammers 15 co-operating with chopping and shearing stator bar members 16. The frangible solids are extracted through holes in an extraction plate 12 and forced as a slurry by a pump 14 through series-connected cyclones 30, 31. The light fraction from the cyclone containing fibres and other organic materials are discharged at 33. The heavy fraction containing aluminium, glass and other heavy particles is delivered by a conveyor 35 to an elutriation tower for washing away any remaining light fraction and is conveyed by a screw 41 to a screen 45 for removal of fines which are discharged through a line 46. The material retained on the screen is acted on by magnetic means 52 to remove any remaining ferrous metals and passed through a dryer 50 before delivery to a shaker concentrator 55 through which an upward current 61 of air may be passed. Concentrated flake-like particles of aluminium alloy are discharged at 63. The remainder is subjected to high tension electrostatic separating forces with the aid of an earthed drum 65 and a high voltage charging electrode 66 whereby glass particles are adhered to the drum and removed by a wiper 67 to be conveyed to a colour type sorter while the rest of the materials is thrown off the drum into a bin 68. From the bin the materials pass to a second shaker concentrator 75 from which overflow material, including any remaining flake-like aluminium particles, is recycled to the first shaker-concentrator 55, whereas underflow material passes through crushing rolls and a screen 81 to recover metal particles, containing predominantly aluminium, and to eliminate crushable non-metallic materials such as stones and ceramics.