Microwave Devulcanization of Cryogenic Crumb Rubber
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Solution Overview
Problem
Current methods for recycling waste tires are inefficient, environmentally harmful, and costly due to the difficulty in devulcanizing vulcanized rubber, leading to low recycling rates and environmental pollution from tire-derived fuels and crumb rubber products.
Innovation Solution
A method involving mechanical shredding, cryogenic micronizing, and microwave-assisted devulcanization to produce surface-modified devulcanized crumb rubber without harsh chemicals, followed by mixing with plastic and extrusion to create an end-of-life tire compound.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If waste tires are shredded and used as TDF (tire-derived fuel), then energy recovery is achieved, but toxic chemicals and carcinogens are released into the environment
Solution Approach 1:
The patent replaces the thermal combustion process (TDF) with a mechanical devulcanization process. The mechanical system uses high-shear mixing and intense mechanical stress to break cross-links in vulcanized rubber, achieving material recovery instead of energy recovery through burning. This substitution eliminates toxic emissions while recovering rubber material for reuse.
Solution Approach 2:
The patent changes the fundamental parameter from thermal energy input (combustion temperature) to mechanical energy input (shear stress, mixing intensity). By using mechanical devulcanization with specific mixing parameters and intensity, the process achieves rubber recovery without the harmful thermal decomposition products generated by TDF combustion.
2Productivity
If harsh solvents are used in recycling methods, then devulcanization efficiency is improved, but environmental pollution and safety issues increase
Solution Approach 1:
The patent replaces chemical solvents with a purely mechanical devulcanization system. The mechanical energy from high-shear mixing and intensive mechanical stress breaks the cross-links without requiring any chemical agents. This eliminates solvent-related environmental pollution while maintaining devulcanization efficiency through optimized mechanical parameters.
Solution Approach 2:
The mechanical devulcanization process uses the rubber material itself and the mechanical energy input to achieve devulcanization. The system is self-sufficient, requiring no external chemical agents or solvents. The mechanical stress directly作用于 the cross-linked structure, breaking it down through pure physical means.
3Productivity
If chemical compatibilizers are used in recycling, then processing efficiency is improved, but mechanical properties of recycled rubber deteriorate
Solution Approach 1:
The patent replaces chemical compatibilizers with optimized mechanical processing parameters. The high-shear mixing and controlled mechanical stress achieve effective devulcanization and rubber particle separation without introducing any chemical additives. This preserves the inherent mechanical properties of the recycled rubber while maintaining high processing efficiency through mechanical means.
4Quantity of substance
If conventional devulcanization methods are used, then rubber recovery is achieved, but energy consumption is excessively high
Solution Approach 1:
The patent applies partial devulcanization rather than complete devulcanization. The mechanical processing is optimized to achieve sufficient cross-link breakdown for effective rubber recovery without excessive energy input. This partial action approach recovers the necessary amount of rubber material while minimizing energy consumption by avoiding over-processing.
Solution Approach 2:
The patent optimizes mechanical processing parameters (mixing speed, shear rate, processing time) to achieve energy-efficient devulcanization. By carefully controlling these parameters, the process achieves effective rubber recovery at lower energy consumption compared to conventional high-temperature or prolonged mechanical processing methods.
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
This method achieves efficient, scalable, and environmentally friendly recycling of waste tires with reduced energy consumption, producing a high-quality rubber compound suitable for various applications, including new tires and TPV/TPE formulations, while eliminating the need for chemical compatibilizers.
Implementation Method 1
applying a dose of microwave energy to the micronized crumb rubber of a frequency and a power sufficient to sever sulfidic cross-links in the surface of the micronized crumb rubber
Implementation Method 2
cryogenic freezing of the waste tires and comminuting the cryogenically frozen waste tires
Data Source
AI summary
A system and a method for producing a surface devulcanized crumb rubber from vulcanized crumb rubber. The method comprising applying a dose of microwave energy to micronized vulcanized crumb rubber sufficient to sever sulfidic cross-links in the surface of the micronized vulcanized rubber crumb to produce a devulcanized crumb rubber. In aspects, the method relates to a method for producing an end-of-life tire compound from vulcanized crumb rubber comprising obtaining a surface devulcanized crumb rubber; mixing the surface devulcanized crumb rubber with a plastic polymer and/or an oil to form a devulcanized rubber mixture; and extruding the mixture through an extruder to produce the end-of-life tire compound.