DEM Modelling of Vibratory Screens

Sammanfattning: In Sweden, about 100 million tons of aggregate is used for road, railway, and concrete every year. Crushing is the main process for producing aggregate material in different fractions. The production process is divided into two sub-processes: comminution or size reduction and classification. The vibratory screen is one of the separation machines used to make a final separation to produce the products based on a grade or a size range. In an industry where logistics plays an important role, the transport of unnecessary materials can be costly and it is therefore critical to screen these materials before transporting them. Industrial vibratory screens are costly and also have a substantial effect on the quality of the final product. Therefore, selecting the correct vibratory screen for the crushing plant at the outset results in a better return on investment and better quality products. The main aim of this research is to understand the screening process in different conditions such as different particle size distribution (PSD) and different feed rates. The first step towards achieving the screening model is to understand the influence of different machine parameters and material properties in the screening performance. Some of these parameters have been studied in this research, such as the motion type, the material of the screen media, and the aperture shape. The Discrete Element Method (DEM) has been used to study these parameters with the idea that by using DEM simulation the particle-to-particle and particle-to-geometry interaction can be studied in a way that is impossible to achieve by real experiments. The study results show that some of the factors have a greater influence on screening, such as the effect of the motion type for the different slope of the deck. Elliptical motion is more efficient compared to linear motion. Also, the aperture shape in different parts of the screen deck has a different effect when using a single-layer or multi-layer material in the feeding point. The result of this research needs further investigation to study the effect of the interaction between different factors before achieving the complete screen model. Another achievement of this research work is to investigate the validation of DEM modelling in screening performance by using a laboratory-scale vibratory screen.

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