Repulping Used Paper Bags with Tensioned Wave Screening
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Solution Overview
Problem
Used paper bags, composed of kraft paper with plastic barrier layers, are not effectively recycled due to their composition, leading to rejection in the pulping process and thermal recycling, necessitating improved cleaning and recovery methods.
Innovation Solution
A device and method utilizing a tensioned shaft screening machine with screen mats that separate paper pieces by size and vibration, combined with a shredder fan and block separator, to achieve intensive loosening and segregation of paper and impurities, followed by a press to form product bales.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If used paper bags are processed in the general paper and cardboard recycling stream, then they are taken to paper mills, but they are rejected as rejects from the pulping process due to their composition and construction
Solution Approach 1:
The paper bags are shredded into smaller pieces to separate the plastic barrier layers from the kraft paper, enabling the paper fraction to be processed in the pulping process while the plastic fraction is removed and handled separately
Solution Approach 2:
The plastic barrier layers and other impurities are extracted and removed from the paper stream through screening and separation processes, leaving clean kraft paper that can be successfully processed in the pulping process
2Manufacturing precision
If the paper bags are shredded and sieved, then the paper pieces are separated by size, but the quality of cleaning and degree of recovery vary significantly with different processes
Solution Approach 1:
A vibratory screening machine is used to separate paper pieces by size and to remove impurities through vibration-induced loosening and segregation, achieving high cleaning quality while maintaining a relatively simple process structure
Solution Approach 2:
The mesh size of the screen and the vibration parameters are optimized to achieve the desired cleaning quality and recovery degree for the specific feed material composition
3Manufacturing precision
If a tensioned screen machine is used for separation, then intensive loosening and segregation of paper pieces and impurities is achieved, but the device complexity increases
Solution Approach 1:
The tensioned screen machine utilizes mechanical vibration to create a trampoline effect that intensively loosens and segregates paper pieces from impurities, achieving high separation efficiency through controlled vibrational motion rather than complex mechanical structures
Solution Approach 2:
The screening process employs dynamic vibration with adjustable frequency and amplitude to optimize separation for different feed materials, allowing the system to adapt to varying input conditions without requiring multiple static screening stages
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-quality cleaning and recovery of paper, reducing residual contents to less than 20% by weight and moisture to less than 30%, with a throughput of over 20,000 tons annually, ensuring compliance with environmental regulations and maximizing paper yield.
Implementation Method 1
The operating principle of the tension wave screen machine is based on the use of vibrations to separate materials. The machine consists of one or more screen mats that are set into vibration by tension waves.
Implementation Method 2
The machine consists of one or more screen mats that are set into vibration by tension waves. The vibrations cause paper pieces of different sizes to be transported across the screen mat.
Implementation Method 3
the screen overflow is drawn through a shredder fan, with a block separator being installed upstream of the shredder fan
Data Source
Figure 1
AI summary
The invention relates to a device (100) and a method for processing used paper bags, which are shredded into pieces of paper on a shredder (130), wherein the pieces of paper are separated according to size and freed from impurities on a tensioned wave screen machine (220), and wherein the screen overflow is compressed into product bales on a press (430).