Patent GB-1448123-A (GB)
Title: Recovery of fibres from waste material
IPC: B03B9/06
Filed: 1973-11-29
Abstract: 1448123 Recovering fibre from waste JETZER ENG AG 29 Nov 1973 [4 Dec 1972] 55367/73 Heading D1F In a process for the recovery of fibres from waste (household, agricultural, forestry and/or organic industrial and commercial waste-refuse, rubbish, trash, garbage, debris) which contains aerobically unstable components e.g. sugar, protein, starch, fat, the waste is contacted, perhaps successively, with at least one solvent capable of dissolving at least part of such components, whereby to minimise the odour of the recovered fibres. The waste may then be dried and it may be comminuted and/or subjected to partial aerobic decomposition before, and/or heated to a temperature in excess of 100C before or after, the solvent treatment. The solvent may comprise water, alcohol e.g. ethyl or isopropyl alcohol, methanol and butanol, an emulsifier e.g. hexane, benzene, aromatic hydrocarbons such as benzol, xylol and toluene, chlorinated hydrocarbons such as methylene chloride, chloroform, carbon tetrachloride, and/ or a surfactant e.g. polyglycol ether and anionic sulphonates. As shown, raw waste from a collection which weighed at 1 is dumped into a silo 3, then conveyed by grab bucket 4 to a dosing belt 5 whence it falls into and passes to impact pulverisers 6 and 7 for coarse and fine reduction. Waste then passes by a magnetic separator 8 (the separated metallic pieces passing to a packing press 9) and is conveyed by bucket chain conveyor 10 to a vibrating sleeve 11: material passing therethrough travels to a belt conveyor 15 and the rest is ejected onto a belt conveyor 12 which carries it past a magnetic separator 13 and into an impact pulveriser 14 the output of which is also received on conveyor 15: waste moves past a magnetic separator 13' and is thrown onto a bounce band 16 for the separation and removal of hard substances. The waste is passed by a bucket or drag chain conveyor 17 into a silo 18 whence it is removed by a transfer plate conveyor 19 and transferred by a conveyor 20 to a drying drum 21, optionally via a fermentation drum 2. In the latter, the waste may be retained, and constantly rotated for one to four days at a temperature of about 50C so that unstable components are aerobically decomposed to a considerable extent and semi-stable components such as cellulose or lignim are partially so composed. In the drum 21 the waste is heated to a temperature in excess of 100C and dried (with sterilisation) and is withdrawn into a cyclone 24 whence exhaust gases flow to a gas washer 23. Waste leaves cyclone 24 through a rotary gate valve 25 and is transferred by a conveyor 26 to a four-stage graded sieve 27 the various fractions of which are separated, pulverised, washed and recycled. Waste from sifter 30 passes into washing or dissolving apparatus 32, 32' wherein the waste is contacted by the solvent and unstable components are dissolved or washed out, the impure solvent being regenerated and recycled to apparatus 32, 32', from container 33. Waste residue is moved by screw conveyor 49 into a drying drum 36 wherein it is heated to a temperature of 60- 140C, the solvent vapour being forwarded to distillation apparatus 35. The dried waste residue issuing from drum 36 in the form of gray, odourless, sterile fibres passes into a cyclone 37 and travels therefrom through a rotary gate valve 38 to a two-stage-sieve 43 the yield of which is conveyed to silos 46, 47. The obtained fibres may be mixed with a binder e.g. urea formaldehyde or phenol resin, and formed into panels or boards or as insulation or filler material.