Polymer Waste Separation Using Electrostatic and Airflow Sorting
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Solution Overview
Problem
Existing methods for recycling plastic waste contaminated with fibers are inefficient, costly, and result in low-purity polymer particles due to high contamination with non-polymer particles, and lack effective electrostatic separation and specific operating speeds.
Innovation Solution
A method involving grinding, mechanical treatment with a hammer mill, sieving, densimetric separation, and electrostatic separation, combined with air flow and turbulence, to achieve high-purity polymer pellets by separating polymers from adhered sheet materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If water tank separation is used to separate polymer from fiber contaminants, then separation can be achieved based on density differences, but operating costs increase and processing time is extended
Solution Approach 1:
The patent replaces the water-based mechanical separation system with an electrostatic separation system. The electrostatic separator uses electric fields to separate polymer particles from fiber contaminants based on their different electrostatic properties, eliminating the need for water tanks and associated mechanical agitation systems, thereby reducing operating costs and processing time while maintaining separation effectiveness
Solution Approach 2:
The patent changes the separation parameter from density-based (water separation) to electrostatic charge-based separation. By applying electrostatic charges to the mixed material and utilizing the different electrostatic properties of polymer particles versus fiber contaminants, the system achieves separation without requiring water immersion, thus improving processing speed and reducing operational complexity
2Productivity
If cyclone separation and sieve methods are used to separate polymer particles, then processing speed improves, but manufacturing precision and purity of isolated polymer particles deteriorate
Solution Approach 1:
The patent replaces mechanical separation methods (cyclone and sieve) with electrostatic separation. The electrostatic separator distinguishes polymer particles from fiber contaminants based on their electrostatic charge characteristics rather than size or density alone, achieving high purity separation while maintaining rapid processing speeds that mechanical methods cannot match
Solution Approach 2:
The patent introduces an electrostatic field as an intermediary separation mechanism. This electrostatic field acts as a mediator that selectively interacts with polymer particles and fiber contaminants based on their different electrostatic properties, enabling precise separation that neither mechanical cyclone nor sieve methods can achieve alone
3Quantity of substance
If light particle fraction is sorted to maximize polymer isolation yield, then polymer yield increases, but contamination with non-polymer particles increases
Solution Approach 1:
The patent changes the separation criterion from density-based (light particle fraction sorting) to electrostatic charge-based separation. This parameter change allows the system to identify and separate polymer particles from non-polymer contaminants based on their electrostatic properties rather than just density, thereby achieving high polymer yield while maintaining high purity by preventing co-separation of contaminated light particles
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
The method achieves high-purity polymer pellets with near-virgin quality, suitable for reuse, through a dry, automated process with high yield and efficiency, effectively removing contaminants like aluminum and paper.
Implementation Method 1
The ground waste is fed into a hammer mill, wherein the ground waste is mechanically treated, thus generating a sheet material fraction and a polymer fraction
Implementation Method 2
mechanically treated by means of a hammer mill
Implementation Method 3
separating of the polymer fraction from the sheet material fraction
Implementation Method 4
A further embodiment of the invention comprises a processing step using a generated air flow and / or air turbulence, thus enhancing separation efficiency
Implementation Method 5
EP 508 discloses a method wherein the light particle fraction, a residual fraction with mainly non-polymer particles and a minor amount of polymer particles, is sorted to maximally isolate the polymer particles
Implementation Method 6
Preferred embodiments of the method are shown in any of the claims 2 to 10
Data Source
Figure 1
AI summary
The current invention relates to a method and an apparatus for recycling waste material comprising a polymer and a sheet material adhered to said polymer, wherein said polymer and sheet material will be separated.