APPLICATION OF THE MATHEMATICAL FRAMEWORK OF COMPUTATIONAL FLUID DYNAMICS FOR THE INVESTIGATION OF GRAVITY CONCENTRATION PROCESSES OF MAGNETITE ORES IN SPIRAL SEPARATOR

Abstract

Using the example of determining the velocity of free and hindered settling of particles, the feasibility of applying computational fluid dynamics methods has been established for modelling the process of sedimentation of mineral particles in a fluid and for determining their settling velocity. The separation efficiency in spiral concentrators is strongly influenced by the interplay between particle size and density. An increase in particle diameter reduces the impact of flow turbulence, stabilizing particle trajectories and enabling a clearer fraction separation. Numerical modelling using the finite element method (FEM) in FreeFEM++ was employed to determine the hydrodynamic and kinematic characteristics of the flow, which can be used to optimize both the design parameters and operational regimes of spiral concentrators to enhance the selectivity of gravity separation of magnetite ores. The development of a three-dimensional flow model has enabled detailed analysis of turbulence zones, local enrichment areas, and concentration distribution across the channel width. These studies can be further extended using OpenFOAM or COMSOL software, both of which are compatible with FreeFEM++ through mesh file exchange. The simulation results were validated by physical experiments conducted on the SVSh-2-1000 spiral separator, which features a parabolic cross-section geometry, and on a laboratory-scale separator with a cross-section profile in the form of a gently inclined curve. The laboratory concentrator produced a concentrate with higher yield, magnetite content, and recovery (up to 85.4 %). Magnetite losses in tailings were 12.5 % for the laboratory unit SVSh-2-1000 and did not exceed 3 %. The obtained results demonstrate a strong correlation between numerical predictions and experimental data, confirming the high potential of computational fluid dynamics in investigating and optimizing gravity separation processes in spiral concentrators.