Covered Screen Bed Plastic Separation by Size and Density

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Existing methods for recycling waste streams, particularly from automobile shredder residue (ASR) and whitegood shredder residue (WSR), struggle to efficiently separate valuable plastics like polypropylene (PP), polyethylene (PE), acrylonitrile butadiene styrene (ABS), and polystyrene (PS) from undesirable plastics such as PVC and plastics filled with talc or glass fibers, leading to lower-quality recycled materials and increased landfill waste.

Innovation Solution

A system and method utilizing a covered screen bed with multiple processing steps, including a screen with variable screening sizes and gravity separators set at specific gravities (0.95-1.05 and 1.05-1.25) to separate plastics based on size and density, followed by a sink-float process to recover lighter and heavier plastics, and a dewatering screen to remove moisture.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If traditional separation methods are used for plastics in waste streams, then the separation process is simpler, but the quality of separated plastic streams is lower and contamination with undesirable plastics remains high

Engineering Contradiction:

Improvequality of separated plastic streamsVSAvoidcomplexity of separation system

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The separation process is divided into multiple sequential stages: initial screening to remove large contaminants, followed by sink-float separation to divide plastics by density, and final refinement to remove undesirable plastics. Each stage targets specific contaminants and produces progressively purer plastic streams, resolving the contradiction by breaking down the complex separation task into manageable segments that collectively achieve high purity.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The system exploits differences in physical parameters (density, size, shape) of various plastics to achieve separation. By adjusting the density of the floatation medium and controlling screen mesh sizes, the system selectively separates desirable plastics from undesirable ones based on their unique parameter profiles, enabling high-quality separation without requiring overly complex equipment.

Inventive Principle:

Principle #35Parameter changes

2Manufacturing precision

If multiple processing steps are implemented to remove undesirable plastics, then the purity of recycled plastics is improved, but the processing time and operational complexity increase

Engineering Contradiction:

Improvepurity of recycled plasticsVSAvoidprocessing time

Core Design Contradiction:

Manufacturing precisionVSLoss of time

Solution Approach 1:

The system performs preliminary removal of large contaminants and obvious undesirable plastics through screening before the main sink-float separation process. This preliminary action prevents contamination of the separation medium and reduces the burden on subsequent processing stages, achieving high purity without requiring excessively long processing times at each stage.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The separation process is designed as a continuous flow system where plastics move sequentially through screening, sink-float separation, and refinement stages without interruption. This continuous operation maintains separation efficiency and purity while minimizing idle time between processing steps, balancing purity requirements with processing speed.

Inventive Principle:

Principle #20Continuity of useful action

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This approach enables efficient separation of plastics into high-quality, uniform streams, maximizing revenue recovery and minimizing landfill waste by producing purified plastics suitable for further processing and recycling.

Implementation Method 1

screening to create distinct streams of light, heavy, or sized plastics

Methodology Applied

Scientific EffectScreening: Filter (physical)

Implementation Method 2

a first gravity separator with a specific gravity between 0.95 and 1.05, separating them into denser materials that sink and lighter materials that float

Methodology Applied

Scientific EffectGravity separation: Gravitation

Implementation Method 3

a sink-float process to recover lighter and heavier plastics

Methodology Applied

Scientific EffectBuoyancy: Archimedes' Principle (Buoyancy)

Implementation Method 4

a dewatering screen to remove moisture

Methodology Applied

Scientific EffectDewatering: Filter (physical)

Data Source

PatentUS20260048530A1Method and System of Separating Plastics Using a Covered Screen Bed

Publication Date: 2026.02.19 VALERIO THOMAS A

AI summary

A method and system for separating materials using a combination of screen beds and gravity separators is included. Materials are collected from the waste stream and pass through a screen. The collected larger materials are then directed to a first gravity separator with a specific gravity. Plastics are recovered and residual metals are recovered.