Particulate flow modelling in a spiral separator by using the Eulerian multi-fluid VOF approach

The Euler-Euler model is less effective in capturing the free surface of flow film in the spiral separator, and thus a Eulerian multi-fluid volume of fluid (VOF) model was first proposed to describe the particulate flow in spiral separators. In order to improve the applicability of the model in the high solid concentration system, the Bagnold effect was incorporated into the modelling framework. The capability of the proposed model in terms of predicting the flow film shape in a LD9 spiral separator was evaluated via comparison with measured flow film thicknesses reported in literature. Results showed that sharp air–water and air-pulp interfaces can be obtained using the proposed model, and the shapes of the predicted flow films before and after particle addition were reasonably consistent with the observations reported in literature. Furthermore, the experimental and numerical simulation of the separation of quartz and hematite were performed in a laboratory-scale spiral separator. When the Bagnold lift force model was considered, predictions of the grade of iron and solid concentration by mass for different trough lengths were more consistent with experimental data. In the initial development stage, the quartz particles at the bottom of the flow layer were more possible to be lifted due to the Bagnold force. Thus, a better predicted vertical stratification between quartz and hematite particles was obtained, which provided favorable conditions for subsequent radial segregation.