S M Arifuzzaman
Particle-Scale Numerical Study on Screening Processes
Particle screening is one of the most commonly used unit operations in various industrial processes for the classification of particles according to their sizes, such as in mineral processing, pharmaceutical industries, food, plastics, recycling and agricultural industries. The design, control and optimisation of screening operations are important to the performance and profitability of the whole processing industry. In this study, a comprehensive literature review is conducted on different industrial screens. Their differences in geometry, operational conditions and applications are compared. In particular, the performances of these screens are found to be not only dependent on the screens, but also very much dependent on the properties of particles they handle. These properties include particle shape, particle size distribution, and mechanic and surface properties. Therefore in the present industrial screening processes, the largely used macroscopic models cannot be general to different kinds of particles. This is because the dynamic characteristics of granular particles are very complicated due to the complex interactions between individual particles and their interactions with screens. To overcome this deficiency, numerical simulations based on the discrete element method (DEM) have been increasingly used in the study of screening processes.
In the project, DEM has been used to predict the screening performance and optimise the production cost of plants. However, there are two aspects that are not fully addressed in these studies. Firstly, it lacks a way to accurately calculate particle interaction force in DEM, especially for non-spherical particles. Secondly, most present DEM studies have not linked the particle-scale analyses to macroscopic screening theories. This project aims to study industrial screening processes by mainly using DEM simulations. The study will focus on understanding the fundamentals of the complicated processes by investigating the mechanisms of the different controlling factors through particle-scale analyses. The particle-scale analyses will also be linked to several macroscopic models of screening, such as the percolation, segregation, stratification and kinetic reaction theories. The integrated study will lead to a better understanding on the fundamentals of screening, and will also provide improved macroscopic models for industrial applications. Such models will be particularly applied to two complicated screens that have not been well understood, the banana screen and trammel screen. To more accurately model non-spherical particles, the recently developed orientation discretisation database solution (ODDS) will be further developed and applied.
Research Project Supervisor/s:
Doctor Kejun Dong (Principal), Doctor Qinghua Zeng, Associate Professor Haiping Zhu
S M Arifuzzaman, Kejun Dong, Qinfu Hou, Haiping Zhu and Qinghua Zeng (2020), Explicit contact force model for superellipses by Fourier transform and application to superellipses packing, Powder Technology, 36(1) ,112-123. https://doi.org/10.1016/j.powtec.2019.10.018