| 摘要 |
<p>1473274 Separating a mixture of plastics MITSUI MINING & SMELTING CO Ltd 13 March 1975 [14 March 1974 (2)] 10486/75 Heading B2H A mixture of plastics containing at least two of polyethylene, polypropylene and a polystyrene is separated into its components by flotation in an aqueous liquid medium containing a wetting agent. When the mixture contains a polystyrene, the polyethylene and/or the polypropylene floats and the polystyrene is recovered as a residue. When there is no polystyrene present, the polypropylene floats and the polyethylene is recovered as a residue. Suitable wetting agents include sodium lignin sulphonate, calcium lignin sulphonate, tannic acid, a quebracho extract, gelatin, glue and saponin. A gas e.g. air, oxygen, nitrogen, carbon dioxide or argon, is introduced into or generated within the aqueous medium by mechanical stirring, bubbling a gas through the medium, releasing gases dissolved under pressure, vacuum evacuation to release dissolved gases or electrolysis. The aqueous medium may contain NaCl, CaCl 2 , MgCl 2 , MgBr 2 , MgSO 4 , CaSO 4 , K 2 SO 4 , Na 2 SO 4 , Ca(HCO 3 ) 2 and NaHCO 3 and may be warmed.</p> |
