Multistep separation of plastics
AssigneeMBA Polymers, Inc.
InventorsLaurence E. Allen, Brian L. Riise, Paul C. Allen, Ron C. Rau, Michael B. Biddle
Life of this patent
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Abstract
Multistep recycling processes for preparing recycled plastic materials. The processes feature a sequence of operations selected from the group consisting of preprocessing operations, size reduction operations, gravity concentration operations, color sorting, sorting by thickness, friction, or differential terminal velocity or drag in air, surface to mass control operations, separation processes enhanced by narrow surface to mass distributions, blending operations, and extrusion and compounding operations. Plastic-rich mixtures are subjected to the process, and one or more recycled plastic materials are collected as outputs of the sequence of processes.
Claims42
A plastic recycling process, comprising:
- receiving a plastic-rich mixture that includes at least two types of plastics;
- determining the plastic-rich mixture to have at least one property, wherein the property is an amount of metal in the mixture, a range of densities, a difference in thicknesses, friction, adhesion or elasticity, different relative charging characteristics, different conductivity, an amount of trapped moisture or gases, a range of colors, a particle size or a difference in viscosity;
- selecting, based on the at least one property, at least six processes for processing the plastic-rich mixture, wherein the selection is also based on a type of a feed source for the plastic-rich mixture, a geographical origin of the feed source, or a temporal distribution of the types of plastics in the mixture, wherein the at least six processes comprise the following sequence of processes in an order of:
- a) a preprocessing step;
- b) a size reduction step;
- c) a surface to mass control process, which involves sorting with an air table and which results in two or more fractions that each have a narrow distribution of surface to mass ratios;
- d) a separation process which separates a first plastic type from a second plastic type and is enhanced by the narrow distribution of surface to mass ratios, the process involving either electrostatic sorting, froth flotation, or density differential alteration, wherein the two or more fractions resulting from the surface to mass control process are treated by the separation process separately from one another;
- e) a blending step;
- and
- f) an extrusion step;
- subjecting the plastic-rich mixture to the sequence of processes;
- and
- collecting a recycled plastic material as an output of the sequence of processes.
Dependencies are inferred from the claim text.