Discrete Element Simulation and Validation of a Mixing Process of Granular Materials

Modeling Technology of Bonded Particle Model for Gold Ore and Its Validation Based on Drop Weight Test

In recent years, studies have focused mainly on the selection of appropriate parameters for ore crushing technology to achieve optimal distributions of particle sizes. The control of particle sizes in mineral processing plays a significant role in improving mineral separation efficiency. The discrete element method (DEM) is an effective numerical simulation method for studying the process of mineral crushing, which can deal with the problem of deformation and movement of discontinuities, that is, the problem of cracks caused by mineral crushing, which is difficult to be solved by traditional continuum mechanics simulation methods. Additionally, the transformation of a mechanical model from continuum to discontinuum mechanics can be realized simply and effectively, so the discrete element method has obvious advantages in the simulation of mineral crushing. However, the accuracy of the DEM simulation is highly dependent on the mathematical models used. In this paper, methodologies for selecting particle sizes and inter-particle bond energy are proposed based on the results of the drop weight test carried out in the laboratory. Particle sizes and inter-particle bond energy are the key parameters for bonded particle model used in discrete element simulation. The suitable parameters proposed by methodologies were applied to construct the bonded particle model for the ore, and its particle size distribution was obtained by simulating the impact crushing process using DEM. The particle size distributions obtained from both the DEM simulation and the drop weight test were in good agreement. The average errors under the three impact energies were 1.96%, 3.31%, and 1.66%, which indicated that the modeling technique proposed in this paper can represent the crushing characteristics of ore materials and improve the accuracy of the DEM simulation. It lays the foundation for guiding the reasonable selection of grinding process parameters and mill equipment.

Numerical Investigation on the Sieving Performance of Elliptical Vibrating Screen

Screening techniques have been widely deployed in industrial production for the size-separation of granular materials such as coal. The elliptical vibrating screen has been regarded as an excellent screening apparatus in terms of its high screening efficiency and large processing capacity. However, its fundamental mechanisms and operational principles remain poorly understood. In this paper, the sieving process of an elliptical vibrating screen was numerically simulated based on the discrete element method (DEM), and an approach coupling the DEM and the finite element method (DEM–FEM) was introduced to further explore the collision impact of materials on the screen deck. The screening time, screening efficiency, maximum stress and maximum deformation were examined for the evaluation of sieving performance. The effects of six parameters—length of the semi-major axis, length ratio between two semi-axes, vibration frequency, inclination angle, vibration direction angle and vibration direction—on different sieving results were systematically investigated in univariate and multivariate experiments. Additionally, the relationships among the four performance indexes were discussed and the relational functions were obtained. The conclusions and methodologies presented in this work could be of great significance for the design and improvement of elliptical vibrating screens.