Мodeling the dynamics of the overflow product in fine wet screening of iron ore

Abstract

Screening or sifting is widely used in the mining industry to separate ore particles by size. Huge volumes of ore at mining enterprises are regularly subjected to industrial screening, so studying the kinetics of the process and optimizing the corresponding technology is of great economic importance. Solving this problem is complicated by the presence of many working variables and various disturbing factors that determine the results of this technological operation. Firstly, these include the complex distribution of ore particles by size and density, as well as the complex influence on the movement of the oversize product of various dynamic operating modes of the screening surface. Recently, fine wet screening screens have been increasingly used for the classification of crushed ore at enrichment enterprises. The use of wet material for screening, the solid phase of which includes ore particles of different densities and sizes, imposes additional requirements on the design and adjustment of the corresponding working equipment. During continuous screening, when the feed rate of ore material to the screen is high enough, and it creates a concentrated layer of particles of a certain thickness, for example, around the feed section, only the particles in the layer that are in direct contact with the screen have a chance to pass through the openings. As long as the upper layers are able to add small particles to this contact layer, the material flow rate will remain constant. As the material moves along the screen and more and more smaller particles pass through the holes, it becomes more dispersed. At the same time, the particles become more mobile and “separated,” transitioning from a “clumped” state to “separated” motion. These features significantly complicate the task of forming effective automated control of this process. The model of the dynamics of crushed ore material on the screening surface of a vibrating screen was studied, taking into account the advection, diffusion, segregation, and percolation of its particles in the material layer. The approach used allows taking into account the transformation of the particle size distribution of the solid phase of the oversize product and its density during movement on the screen surface. This improves the quality of automated control of the process.