Method of and apparatus for continuously treating comminuted synthetic plastic containers and products having contaminants bonded thereto for recycling purposes

A method of continuously treating plastic flakes produced by comminuting synthetic plastic containers and products having cellulosic or plastic labels or other contaminants bonded thereto, which comprises the steps of:

• a. passing the flakes in a flow stream through a cryogenic housing subjecting the stream to cryogenic temperatures;
• b. hurling flakes from the stream against a diffuser ring having circumferentially spaced openings which are undersized relative to the maximum dimension of the flakes and impacting them with a bond disintegrating force against the diffuser ring, and hurling said flakes through said openings and against an outer impact wall to impact each flake individually against said impact wall without interference from other flakes of a nature which might shield the flake to thereby yield a discharge stream comprising flakes and any separated contaminant or fluff generated;
• and
• c. passing the discharge stream from step b through a separator to remove any fines and fluff produced from the flakes while discharging the flakes, free of contaminant, in a flow stream.

A system for separating contaminants from the plastic flakes obtained by granulating synthetic plastic containers and other synthetic plastic products which have contaminants bonded thereto comprising:

• a. a cryogenic housing for receiving the flakes;
• b. transport means incorporated with the housing for moving the flakes in a flow stream through the housing;
• c. means associated with the housing for contacting the flakes with a refrigerant medium which will subject the flakes to a flake freezing temperature;
• d. an impeller for receiving the frozen flakes centrally in a flow stream having means for channeling them radially in separated single file;
• e. an impact wall circumferentially outboard of the impeller in radial alignment therewith;
• and
• f. diffuser means, fixed relative to said impeller between the impeller and impact wall, and having circumferentially spaced openings;
• and
• g. means for rotating the impeller at speeds to hurl the flakes individually at said diffuser means, and through the openings at the impact wall with sufficient force to break the bond between the flakes and the contaminant.

A method of continuously treating the scrap flakes produced by comminuting plastic containers and products having cellulosic or resin labels or other contaminants bonded thereto, comprising the steps of:

• a. passing the flakes in a flow stream through a cryogenic housing while mixing them with a refrigerant to subject the stream to cryogenic brittlizing temperatures;
• b. discharging the flakes in a flow stream to an impeller having radially open closed passages;
• and
• c. radially separating the flakes and hurling them individually with a bond disintegrating force at and through a diffuser ring having openings of a size to pass those which are hurled directly to an opening only individually, against an impact wall to impact each flake individually without interference from other flakes of a nature which might shield the flake being impacted.