Discrete Element Simulation and Economics of Mechanochemical Grinding of Plastic Waste at an Industrial Scale

Efficient and sustainable chemical recycling pathways for plastics are vital for addressing the negative environmental impacts associated with their end-of-life management. Mechanochemical depolymerization in ball mill reactors is a new promising route to achieve solid-state conversion of polymers to monomers, without the need for additional solvents. Physics-based models that accurately describe the reactor system are necessary for process design, scaling up, and reducing energy consumption. Motivated by this, a Discrete Element Method (DEM) model is developed to investigate the ball milling process at laboratory and industrial scales. The lab-scale model is calibrated and validated with data extracted from videos using computer vision tools. Finally, scaled-up ball mill designs capable of depolymerizing varying feeds of PET waste were simulated, and their capital and operating costs are estimated to assess the economic potential of this route.