Polyolefin Waste Sorting Plant for 2D Fraction Purification
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Solution Overview
Problem
Current methods for sorting polymer-based waste, particularly polyolefins, are inefficient in separating two-dimensional fractions suitable for chemical recycling, leading to high costs and limited application of chemical recycling due to contamination with unwanted materials.
Innovation Solution
A plant and method utilizing a series of mechanical sorting processes including a feeding station, metal removal, optical separation, shredding, and aeraulic separation to achieve a high-purity two-dimensional polyolefin fraction suitable for chemical recycling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If chemical recycling is used to process mixed polymer waste, then high-value regenerated materials can be produced, but the process becomes extremely expensive and technically unfeasible due to contamination
Solution Approach 1:
The sorting process is divided into multiple sequential stages: pre-sorting to remove large contaminants, optical sorting to separate different polymer types, and density-based separation to isolate polyolefins. Each stage handles a specific aspect of purification, making the overall complex task manageable and effective
Solution Approach 2:
The patent performs preliminary sorting actions before chemical recycling to pre-concentrate the polyolefin fraction and remove contaminants. This preliminary purification prepares the waste stream for successful chemical recycling by ensuring the feed material meets the required purity specifications
2Manufacturing precision
If mechanical sorting is used to separate polyolefins from mixed plastic waste, then the purity of the fraction increases, but the sorting process complexity and cost increase
Solution Approach 1:
The patent employs air classification technology where controlled air streams separate polyolefin particles from heavier contaminants based on density differences. This pneumatic separation method achieves high purity without requiring complex mechanical contact between sorting components and waste material
Solution Approach 2:
The sorting process exploits changes in physical parameters, particularly density and aerodynamic properties, to separate polyolefins from other plastics. By adjusting air flow rates and classification parameters, the system optimizes separation efficiency while maintaining relatively simple equipment configuration
3Quantity of substance
If PVC is present in the plastic fraction, then the waste stream represents a larger volume to treat, but PVC causes problems for heat and chemical treatment operations
Solution Approach 1:
The patent specifically extracts and removes PVC from the mixed plastic stream through density-based separation and optical sorting. By taking out the harmful PVC component before chemical recycling, the remaining polyolefin fraction can be processed without the detrimental effects of chlorine-containing materials
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 solution efficiently produces a two-dimensional polyolefin mixture with less than 20% extruded polystyrene and 2% metal fragments, suitable for chemical recycling, reducing contamination and increasing the applicability of chemical recycling processes.
Implementation Method 1
an aeraulic separator configured for separating the three-dimensional polyolefin fraction, comprising the polyolefin fragments with bulk density higher than a predefined threshold value, from the two-dimensional polyolefin fraction, comprising the polyolefin fragments with bulk density lower than the predefined threshold value
Implementation Method 2
at least one optical separator configured for removing from the flow of material to be treated the non-polyolefin polymers, the cellulosic components and the textile components
Implementation Method 3
a first station configured for removing the metal fragments from the flow of material to be treated
Data Source
AI summary
A plant for production of a mixture of waste based on polyolefins and XPS suitable for feeding into a pyrolytic reactor. The plant includes: a feeding station that releases a flow of material to be treated; a first station for removing the metal fragments; at least one optical separator for removing the non-polyolefin polymers and the textile and cellulosic fractions; a screen for removing the foreign bodies with dimensions smaller than a predefined minimum; a shredder for reducing the particle size of the material to be treated; a second station for removing the metal fragments; and an aeraulic separator for separating the three-dimensional polyolefin fraction from the two-dimensional polyolefin fraction. The embodiments also concern a method for the production of a mixture of waste based on polyolefin and XPS, suitable for chemical recycling.