Selective Shredding for Hygiene Product Recycling
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Solution Overview
Problem
Existing shredding devices for disposable hygiene products fail to effectively separate pulp and super absorbent polymer (SAP) from plastic components, leading to contamination in recycling processes due to the production of particles of varying sizes, which can pass through sieves and reduce the purity of plastic streams.
Innovation Solution
A selective shredding system with a revolving device that applies controlled tension and uses adjustable apertures and rotating shafts with fingers to shred products into defined sizes, preventing smaller particles from being further shredded and allowing for efficient sieving and separation of pulp and SAP from plastic components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional shredding devices are used to reduce material size, then particle size reduction is achieved, but particles of varying sizes are produced including small particles that can pass through sieves and contaminate pulp streams
Solution Approach 1:
The shredding device is divided into multiple stages with different cutting elements. Coarse cutting elements perform initial size reduction, followed by fine cutting elements that precisely control final particle dimensions. This segmented approach enables both high productivity and precise particle size control, preventing overshrinking while maintaining efficient processing.
Solution Approach 2:
The device employs adjustable cutting elements and variable speed mechanisms that can be dynamically configured based on material type and desired output specifications. This dynamic adaptability allows the system to optimize particle size control for different hygiene products while maintaining high processing rates, resolving the contradiction between productivity and precision.
2Manufacturing precision
If larger particles are produced to avoid contamination, then plastic stream purity is improved, but particles may fold and roll up making pulp and SAP extraction problematic
Solution Approach 1:
Different regions of the shredding device apply different cutting intensities and mechanisms. The coarse cutting zone creates initial breaks without excessive force, while the fine cutting zone completes size reduction with precision. This localized quality control prevents particle folding and rolling by avoiding excessive mechanical stress, while still achieving the necessary size reduction for clean separation.
Solution Approach 2:
The device performs preliminary coarse cutting that opens up the hygiene product structure and releases trapped pulp and SAP before final precision cutting. This preliminary action prevents subsequent folding and rolling by eliminating trapped materials that would cause deformation during final size reduction, thereby maintaining particle integrity and stream purity.
3Productivity
If smaller particles are produced to ensure thorough shredding, then complete size reduction is achieved, but smaller particles can pass through sieve holes and contaminate pulp output
Solution Approach 1:
The shredding process is segmented into controlled stages with progressively finer cutting elements. Each stage reduces particle size to a specific target range, with the final stage producing particles that are sufficiently small for complete shredding but large enough to be retained by standard sieve holes. This segmentation ensures both thorough processing and pulp stream purity.
Solution Approach 2:
The device incorporates adjustable parameters including cutting gap, blade speed, and feed rate that can be optimized to produce particles within a specific size distribution. By controlling these parameters, the system achieves complete shredding effectiveness while maintaining particle sizes above the sieve hole threshold, preventing contamination of pulp output streams.
4Productivity
If conventional shredding methods are used, then processing speed is maintained, but separation function is insufficient requiring significant space and energy
Solution Approach 1:
The device merges shredding and separation functions into a single integrated system. The multi-stage cutting elements not only reduce particle size but also create geometric characteristics that facilitate immediate separation in downstream equipment. This merging maintains high processing speed while achieving effective separation, reducing the need for additional space and energy-consuming separation stages.
Solution Approach 2:
The system uses dynamic control of cutting parameters to optimize both processing speed and separation efficiency simultaneously. Variable speed mechanisms and adjustable cutting geometries allow the device to adapt to different material compositions, maintaining high throughput while ensuring particles are sized and shaped for efficient separation, thereby reducing overall system space and energy requirements.
Data Source
AI summary
System having an apparatus (10) for shredding hygiene products (12), which operates within a revolving device (22).