Terahertz Transmission Sorting for Black Plastics
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current recycling methods, particularly for black plastics and multi-layer plastics, face challenges in achieving high accuracy and reliability in sorting due to low light reflection and absorption, leading to impure recyclates and inferior product quality.
Innovation Solution
A device utilizing non-overlapping THz frequency bands with narrow bandwidths, combined with optical scanning, to analyze and sort plastics by evaluating transmission and scanning information, enabling precise identification and separation of different plastic materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If hyperspectral cameras in short-wave infrared are used for sorting plastics, then sorting speed and system price are improved, but measurement accuracy for black plastics deteriorates due to low light reflection and high material absorption
Solution Approach 1:
The patent changes the wavelength parameter of the electromagnetic radiation from short-wave infrared to terahertz frequency range (0.1-10 THz). This parameter change enables penetration through black plastics and multi-layer materials that absorb infrared light, allowing transmission-based measurement that reveals internal structures and achieves accurate classification without sacrificing sorting speed.
Solution Approach 2:
The patent replaces the reflection-based optical measurement system with a transmission-based terahertz imaging system. This substitution allows the measurement beam to pass through the material rather than relying on surface reflection, enabling detection of internal structures and composition of black plastics and multi-layer materials that are invisible to conventional optical systems.
2Measurement precision
If X-ray systems are used to visualize structures below the surface, then measurement accuracy for multi-layer plastics is improved, but device complexity and safety requirements worsen due to ionizing radiation
Solution Approach 1:
The patent changes the energy parameter of the radiation from ionizing X-rays to non-ionizing terahertz frequencies (0.1-10 THz). This parameter change maintains the ability to penetrate materials and visualize internal structures while eliminating the safety hazards and regulatory complexities associated with ionizing radiation, resulting in a simpler and safer system.
3Measurement precision
If THz spectrometers are used for analyzing black plastics, then measurement accuracy is improved, but productivity deteriorates due to slow measurement speed and high system price
Solution Approach 1:
The patent segments the broad THz spectrum into multiple narrow frequency bands (12 GHz wide bands from 84 GHz to 96 GHz, with 128 narrow individual spectra per band). This segmentation allows parallel processing of different frequency components, significantly increasing measurement speed while maintaining the high material identification accuracy provided by spectral analysis.
Solution Approach 2:
The patent uses 128 narrow individual spectra within each 12 GHz frequency band, providing more spectral detail than strictly necessary for basic identification. This excessive spectral resolution enables accurate differentiation of similar materials while the parallel processing of multiple bands maintains high measurement speed for industrial sorting applications.
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 allows for accurate and reliable sorting of black and multi-layer plastics, improving the purity of recyclates and enabling the production of higher-quality materials by using a combination of THz radiation and optical scanning techniques.
Implementation Method 1
a transmission arrangement (1) for irradiating the material flow (M) with THz radiation (SE) and for recording transmitted THz radiation components (ST)
Implementation Method 2
Those THz radiation components ST detected in the receiver (1b) are evaluated after their detection in the receiver (1b) to obtain transmission information TI
Data Source
Figure 1
Figure 2
Figure 3
AI summary
The invention relates to a device for analysing materials in a material flow, (M) with a transmission arrangement (1) for irradiating the material flow (M) with electromagnetic radiation (SE) in the Terahertz wavelength range, in order to detect the THz radiation fractions (ST) transmitted through the material flow (M) and to evaluate said THz radiation fractions (ST), the transmission arrangement (1) being designed to produce, detect and evaluate a plurality of different THz frequency bands (fB) of a small bandwidth and to evaluate a plurality of narrow individual spectra (FE) in each of said Thz frequency bands (fB), said device also comprising a recording system (2) for optically scanning the material flow (M) from at least one side (3o, 3u), the device being designed to carry out the analysis on the basis of both transmission information (TI) obtained by the transmission arrangement (1) by the detection and/or evaluation thereof, and scanning information (AI) obtained by the recording system (2) by the scanning thereof and/or by an evaluation of data generated as a result of said scanning.