Particle size distribution modelling in biomass comminution: Current approaches, limitations and future directions

Efficient milling of lignocellulosic waste biomass is crucial for preparing feedstocks in waste-to-X conversion processes. This review explores particle size requirements, biomass comminution technologies, and current PSD modelling techniques, such as empirical models, neural networks, population balance models, and discrete element methods. Emphasis is placed on their engineering relevance and scalability. The results show that most models are limited to specific materials, mill configurations, and operating conditions, reducing their accuracy outside the calibrated range. Scaling up remains a significant challenge, but physically interpretable models offer the most potential for predictive process design and industrial use. Future research should focus on developing physically based models that link material properties, mill design, and fragmentation behaviour across various scales.