Generalization of a semi-empirical model to predict the efficiency curve of laboratory- and industrial-scale cyclone separators

Cyclone separators play a vital role in steel recycling plants by collecting dust generated during the shredding of scrap, thereby reducing the environmental impact of the process. Accurately predicting the separation efficiency curve is crucial during design to ensure compliance with the performance requirements. To fulfil this task, several physical models are available in the literature, among which the semi-empirical model of Mothes & Loeffler (1988) is unrivalled. In fact, it stands out for its rigourous formulation in predicting cyclones performance. However, some fundamental assumptions of this model were specifically tailored to laboratory-scale cyclones, which operating conditions differs from real industrial plants. Since experimental data to validate the model with industrial cyclones are not available in the literature, concerns exist on the reliability of the model for practical engineering tasks. The aim of this study is to propose a new generalized version of the Mothes & Loffler (1988) model as a reliable practical engineering tool to predict the efficiency curve of both laboratory and industrial cyclone separators. To this end, an experimental campaign on industrial cyclones operation in steel recycling plants has been performed. Accordingly, an enhanced version of the model is proposed, which improves the definition of three fundamental parameters, i.e. particle diffusion coefficient, heterogeneity of mass density, and non-spherical shape. The modified version of the Mothes & Loeffler model demonstrated to extend the validity of the original model to the case of industrial-scale cyclones, reducing the prediction error by 87 % in predicting the separation efficiency curves.