Waste plastic density separation
AssigneeEastman Chemical Company
InventorsBruce Roger DeBruin, Kyle Lyn Collings, James Stewart Nelson
Life of this patent
Estimating the term…
Abstract
Methods and systems for separating mixed plastic waste are provided herein. The methods generally comprise separating the mixed plastic waste into a PET-enriched stream and one or more PET-depleted streams. The separating may be accomplished using the combinations of two or more density separation stages. Exemplary density separation stages include sink-float separators and centrifugal force separators. The PET-enriched and PET-depleted streams may be recovered and/or directed to downstream chemical recycling processes.
Claims24
A waste plastic separation method comprising separating a mixed plastic waste (MPW) into a polyethylene terephthalate (PET)-enriched stream and a PET-depleted stream, wherein said PET-enriched stream comprises at least 70 weight percent PET on a dry basis and at least 0.1 weight percent and not more than 10 weight percent halogens on a dry basis, wherein the PET-enriched stream has a microorganism content of less than 105 CFU/g.
A waste plastic separation method comprising:
- (a) introducing mixed waste plastic (MPW) particulates into a first density separation stage;
- and
- (b) feeding an output stream from said first density separation stage into a second density separation stage,
- wherein one of said first and second density separation stages is a low-density separation stage and the other of said first and second density separation stages is a high-density separation stage,
- wherein said low-density separation stage has a target separation density that is less than 1.35 g/cc and/or at least 1.25 g/cc,
- wherein said high-density separation stage has a target separation density that is at least 0.01 g/cc greater than the target separation density of said low-density separation stage.
A waste plastic separation method comprising:
- a) introducing MPW particulates into a first density separation stage to form a particulate plastic solids output stream and a high-density particulate plastic solids stream having a higher average particulate plastic solids density than said particulate plastic solids output stream, and
- b) feeding at least a portion of said particulate plastic solids output stream into a second density separation stage to form a medium density particulate plastic solids stream and a low-density particulate plastic solids stream,
- wherein the average particulate plastic solids density of the high-density particulate plastic solids stream is higher than the average particulate plastic solids density of the medium density particulate plastic solids stream, and wherein the medium density particulate plastic solids stream has an average particulate plastic solids density that is higher than the average particulate plastic solids density of low density particulate plastic solids stream, wherein said medium density particulate plastic solids stream comprises at least 70 weight percent PET on a dry basis.
A waste plastic separation method comprising:
- (a) mixing a salt and/or saccharide with water to form a concentrated salt and/or saccharide solution and feeding said concentrated salt and/or saccharide solution to at least one of a first or second density separation stages;
- (b) introducing mixed waste plastic (MPW) particulates into said first density separation stage;
- and
- (c) feeding an output stream from said first density separation stage into the second density separation stage,
- wherein one of said first and second density separation stages is a low-density separation stage and the other of said first and second density separation stages is a high-density separation stage,
- wherein no separate caustic component is introduced into said first density separation stage and/or said second density separation stage, and wherein said MPW particulates are not subjected to a separate antimicrobial processing stage, comprising addition of a caustic component, before being introduced into said first density separation stage.
Dependencies are inferred from the claim text.