Numerical and experimental research on the degradation mechanism in a dust-free crusher using DEM-CFD method

作者：Fan, Yiwei; Wang, Zhaohui^*

来源：Computational Particle Mechanics, 2022, 9(3): 569-584.

DOI：10.1007/s40571-021-00431-z

• Ultrafine crushing
• Mechanical physical method
• DEM-CFD gas-solid coupling field
• Network crosslinking density
• Degradation yield

Ultrafine crushing is a prerequisite for achieving efficient recycling of waste thermoset plastics. In order to address the problems of recycling including low utilization, this research investigates rigid thermoset polyurethane foam insulation board as the research object and selects an integrated dust-free crusher designed independently. The crushing tool adopts the mechanical physical method to break down the plastic. By optimizing the crushing process parameters, combined with the particle size distribution law of the thermosetting plastic recycled material and the discrete element parameter calibration method, a crushing model based on the Hertz-Mindlin (with bonding) theory is designed and carried out. The discrete element method-computational fluid dynamics (DEM-CFD) gas-solid coupling field numerical simulation is used to explore the degradation of the recycled material after the optimization of the mechanical equipment. The results are verified with spectroscopic characterization and response surface method tests. It was found that when the optimized parameters of a five-slice blade, a crushing time of 25 min, and a crusher speed of 5500 rpm are used, the network crosslink density of the waste thermoset plastics is successfully broken. Among the materials tested, the crosslink density of the 120 mesh recycled material is very small (0.00074 mol/cm(3)). Many renewable polymerized active groups are obtained, and the degradation yield reaches up to 80.34%.