Interdependence between Segregation and Flow Properties of Bulk Solids

Abstract

This thesis presents the results of an ongoing investigation into the characteristics of segregation, newlinewhich is critical for ensuring product homogeneity and process reliability. Additionally, moisture newlinecontent certainly affects the segregation behaviour of powders, which may degrade the product newlinequality and cause lot rejection. Therefore, understanding the segregation characteristics affected by newlinechanges in moisture content plays a vital role in achieving the desired goals in powder handling newlineindustries. In this research, a deeper understanding of powder segregation and flow behaviour was newlineachieved by addressing a critical gap in the literature for Geldart Group A to B borderline powders, newlineproviding practical insights and predictive tools applicable to real-world scenarios. A key newlinecontribution is the introduction of a novel dimensionless parameter, the modified dimensionless newlinecohesion number, which improves the prediction of segregation in complex powder fluidising newlinesystems. High-accuracy models were developed by incorporating important factors such as moisture, newlinecohesion, flow function, and particle properties. Notably, the research also established clear empirical newlinerelationships between moisture levels and segregation behaviour, an area with minimal prior newlinemodelling despite its industrial significance. By highlighting the role of moisture management in newlinemaintaining product uniformity and preventing lot rejection, this work supports higher safety and newlinequality standards. These models were validated across a diverse set of powders, including fly ash, newlinepharmaceuticals, detergents, and semolina, demonstrating strong generalisability. The study further newlineexplores segregation challenges in pneumatic conveying systems. A 75:25 blend ratio of coarse-to newlinefine ash was found optimal for dense phase flow. Criteria based on the bulk powder Froude number newline(lt10) and coarse-to-fine ratio (gt10) were proposed for reliable conveying. By highlighting the role newlineof moisture management in maintaining product uniformity and preventing