US 5,397,066 AGranted

Separation of plastic materials

AssigneeMobil Oil Corporation

InventorsRichard H. Leitman, Jerry A. Pickering, Lukasz E. Rychlicki

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Abstract

Separation of a mixture of plastic materials by separating the plastic mixture according to particle size, and introducing plastic of similar size particles into a vertical fluidized bed column having an upwardly flowing gaseous stream therein. The flow rate of the gaseous stream is controlled to provide a relatively low density fraction of the plastic mixture exiting at the upper end of the column, and a relatively high density fraction of the plastic mixture exiting at the lower end of the column. In one embodiment, electrostatic charges are induced on the particles of the plastic mixture prior to introducing the plastic of similar size particles into the column, and the column is charged to attract thereto the plastic particles having the highest electrostatic charge.

Claims13

Dependent claims

A method of separating a mixture of at least two different plastic materials comprising the steps of:

providing said mixture in the form of particles, inducing electrostatic charges on the particles of said mixture;
and then introducing said mixture in the form of charged particles into a vertical fluidized bed column having an upwardly flowing gaseous stream therein;
after said inducing, introducing additional particles of plastic into the fluidized bed;
maintaining the flow rate of said gaseous stream to provide a relatively low density fraction of said mixture, including a first plastic, exiting at the upper end of said column and a relatively high density fraction of said mixture, including a second plastic, exiting at the lower end of said column;
and charging said column with a polarity opposite that of the charge on said second plastic for attracting thereto the particles of said second plastic which are of relatively high density and having the highest electrostatic charge relative to said first plastic of a relatively low density.

2 more elements

Dependencies are inferred from the claim text.