Optimization of structural process parameters of rod stirring mill based on discrete element method

Abstract. The rod-type stirred mill is the core equipment used in the grinding of potassium feldspar. However, the grinding process involves numerous parameters that influence performance, various evaluation metrics, and prolonged single-cycle durations, collectively making it difficult to identify optimal operating conditions. To address this challenge, a simulation model of the rod-type stirred mill was developed based on the discrete element method (DEM). This study investigates the effects of rotational speed, grinding media size, and bar spacing on milling performance. By integrating energy efficiency, stirrer wear, collision frequency, and average normal and tangential collision forces, the comprehensive index of milling performance was established. Using Box–Behnken experimental design and analysis of variance, the relative influence of rotational speed, grinding media size, and bar spacing on grinding performance was ranked. With weight coefficients assigned as 0.4 for energy efficiency, 0.2 for stirrer wear, 0.2 for collision frequency, 0.1 for average normal collision force, and 0.1 for average tangential collision force, response surface optimization was conducted. Under the current weighting scheme, the optimal operating parameters of the rod-type stirred mill are determined as follows: a rotational speed of 398 r min−1, a grinding media size of 6 mm, and bar spacing of 21.2 mm. Under these conditions, the predicted comprehensive grinding performance indicator is 0.781, and the error between the discrete element method (DEM) simulation validation results and the predicted value is only 0.77 %.