Abstract
Efficient milling of lignocellulosic waste biomass is critical for its valorisation in Waste-to-X processes. Mathematical modelling of particle size is important for optimising the milling process to produce particles of suitable size for subsequent processing. Currently, empirical models with a narrow range of validity are used mainly. General physically based models could solve this problem thanks to their wide range of validity. This work aimed to create a physically-based model of particle evolution in a knife mill and to validate it for knife-milled beech chips. The particle evolution model evinces an exponential dependence on screen sieve size, rotor rotational speed, mass flow rate, and the initial particle size of the biomass. The predictive model for output particle size D50 was validated by experimental data on screen sieve size under constant rotor rotational speed and mass flow rate. The experimental validation was performed on a Retsch SM 300 laboratory knife mill using a linear rotor blade at different peripheral speeds, mass flow rates, and mesh sizes. The peripheral speed range was 13.6 and 20.4 m s-1, the mesh size range was from 0.75 to 6 mm, and the mass flow range was 10 and 15 kg h-1. The accuracy of created model was confirmed by R2 values of 0.87-0.97 and RMSE values of 0.056-0.119. The proposed model provides a core basis for process optimisation and scale-up in biomass milling applications.
