A process for separation of comminuted plastics waste especially useful for separation and recycling of the synthetic plastic material from carpet waste

摘要

A process for separation of comminuted plastics waste, especially carpet material, in which an aqueous suspension of the plastics material, e.g. carpet material, is prepared in an aqueous phase by fine comminution, and the fractions are separated by making use of the differences in specific gravity of the different particles of suspended materials is new. A process for separation of comminuted plastics waste, especially carpet material, in which an aqueous suspension of the plastics material, e.g. carpet material, is prepared in an aqueous phase by fine comminution, and the fractions are separated by making use of the differences in specific gravity of the different particles of suspended materials. The temperature for fine comminution and also for separation of the fractions is 60-98 deg C. The specific gravity of the suspension both in the first and second separation stages is set by addition of aqueous Ca nitrate solution, where the pH of the second stage separation is adjusted to 4.4-6.0 by addition of HCl or nitric acid, and the aqueous phase of the suspensions has a specific gravity lying between that of the two main components of the plastics waste, and an oxidizing agent is added to the suspension salt solution in the second stage, in amount 1-5 wt.%, and the suspension in the first or second stage is separated into two solid fractions of different specific gravities by means of a double cone completely automatic worm centrifuge (sic), and the aqueous phase is recycled.