Selective separation of polymers for recycling, e.g. from old cars or domestic appliances, comprises separation by density in an aqueous suspension of solid particles, e.g. calcium carbonate, containing a water-soluble stabilizer

摘要

Selective separation of synthetic organic materials by density involves separation in an aqueous suspension containing solid particles with a preferred particle size of not more than 5 microns (in sufficient amounts to give the required separation cut-off density) plus a water-soluble stabilizer for the rheological properties and cut-off density. A method for the selective separation by density with a stability precision of +- 0.0005 based on a separation cut-off density (ds) of at least 1 for each of the components of a mixture of synthetic organic materials, especially fragmented used materials for recycling. Separation is by density differences in an aqueous suspension of solid particles dispersed in amounts sufficient to create the cut-off density (ds) selected for at least one of the components. The starting suspension consists of (a) powder with a particle size of not more than 30 (preferably not more than 5) microns, dispersed in the aqueous phase in the amount required to give the required value of (ds) and (b) a water-soluble additive to stabilize the rheological properties and the non-variation of (ds) with a level of precision of +- 0.0005.