Plastic Waste Polymer Separation Using NIR and MIR Sorting
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Solution Overview
Problem
Existing methods for recycling plastic waste fail to achieve high purity separation of polymers, leading to a loss of value and contamination, and are not capable of continuously processing large quantities without interruption.
Innovation Solution
A method utilizing near-infrared (NIR) and mid-infrared (MIR) spectroscopy, combined with compressed air jets, to identify and separate different types of polymers from plastic waste into high-purity fractions, including black polymers, by distinguishing between colored, white, and black materials, and further refining by melt flow index and color using UV/VIS spectroscopy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If normal separation techniques are used, then the separation process is simple and low-cost, but the purity of the selected polymer is low and heavily contaminated by other polymer types
Solution Approach 1:
The patent segments the separation process into multiple sequential stages: pre-separation by color (black vs. colored/white), then further separation of each fraction into individual polymer types using NIR spectroscopy, and final refinement. This multi-stage segmentation enables high purity (>95%) by breaking down the complex separation task into manageable steps, each targeting specific polymer distinctions.
Solution Approach 2:
The patent replaces simple mechanical separation methods with NIR (near-infrared) spectroscopy-based identification and sorting systems. This substitution enables precise polymer differentiation based on molecular vibrations and chemical bonds, achieving high manufacturing precision through optical and spectral analysis rather than crude mechanical means.
2Loss of energy
If traditional recycling methods are used, then the process is simple, but the loss of value is significant and the original plastic value cannot be restored
Solution Approach 1:
The patent changes the identification parameter from simple visual or mechanical properties to spectral characteristics in the near-infrared range. By analyzing how different polymers absorb and reflect NIR radiation based on their molecular structure, the system can distinguish between polymer types with high accuracy, enabling value restoration through precise sorting that preserves material quality.
Solution Approach 2:
The patent introduces NIR spectroscopy as an intermediary between the plastic waste and the sorting mechanism. This intermediary technology provides detailed information about polymer composition and identity, enabling the sorting system to make informed decisions that maximize recovered value while maintaining processing efficiency.
3Productivity
If continuous processing is implemented, then the productivity is high, but the measurement and identification precision may be compromised due to speed requirements
Solution Approach 1:
The patent implements continuous processing where plastic waste flows continuously through the system while NIR spectroscopy performs real-time identification and sorting occurs without interruption. The useful action of identification and separation continues uninterrupted, maintaining high productivity while achieving >95% purity through rapid spectral analysis and immediate sorting 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
Achieves polymer separation with purity greater than 95%, enabling the production of high-quality recycled materials suitable for direct reuse in the plastics industry, and allows continuous processing of large quantities.
Implementation Method 1
identifying by means of near-infrared (NIR) spectroscopy the flakes of coloured and white plastic material and separating a fraction (F1) rich in said flakes of coloured and white plastic material
Implementation Method 2
identifying by means of mid-infrared (MIR) spectroscopy the flakes of a polymer P3 from said fraction (F2) rich in flakes of black plastic material
Implementation Method 3
separating a fraction (F3) rich in flakes of polymer P1 from said fraction (F1) rich in flakes of coloured and white plastic material by means of appropriate separation means
Implementation Method 4
further refining by melt flow index and color using UV/VIS spectroscopy
Data Source
AI summary
The present invention concerns a method for the selection and separation of polymers originating from urban and/or industrial plastic waste to obtain plastic materials for recycling which comprises a first step of supplying a mixture of polymers composed of flakes of polymers having dimensions ranging from 6 to 100 mm; a step of identification by means of near-infrared (NIR) spectroscopy of the flakes of coloured and white plastic material and the flakes of black plastic material and subsequent separation from one other; several consecutive steps of identification by means of NIR spectroscopy of the different types of polymer from the coloured and white plastic material and subsequent separation of said polymer types.