Calibration of Parameters for Discrete Element Model for Neodymium-praseodymium Oxide Powder Particles

In the process of rare earth metal molten salt electrolysis preparation, exceptionally fine particle size of rare earth powder tends to induce phenomena such as powder bridging and dead zones in flow. To ensure the accuracy of discrete element simulation in the powder conveying and feeding process, accurate contact parameters for neodymium-praseodymium oxide particles need to be obtained. Prior to the conducting simulation experiment, experimental measurements of the particle size, density, and angle of repose parameters of neodymium-praseodymium oxide powder were conducted. In the discrete element simulation experiment, the Hertz-Mindlin contact model with JKR cohesion and the particle contact scaling principle were chosen as the basis for contact parameter calibration. Key factors significantly affecting the angle of repose simulation experiment were selected through Plackett-Burman tests. The best significant parameter range was determined through steepest ascent experiments. Based on Box-Behnken tests and response surface design, the design and optimization of a second-order regression model for the angle of repose and significant parameters were completed, resulting in the optimal parameter combination: The rolling friction coefficient between neodymium-praseodymium oxide particles is 0.242, the JKR coefficient is 0.148 J/m², and the rolling friction coefficient between neodymium-praseodymium oxide and stainless steel is 0.397. The validation results showed that the relative error between the simulated and measured values of the angle of repose was 1.06%. The calibrated parameters for neodymium-praseodymium oxide powder particles are reliable and can provide a reference for subsequent powder conveying and feeding process simulations.