Research of the Collision Mechanics Model and Time-Frequency Characteristics during the Multistage Variable-Inclination Screening Process for Clean Coal

[Image: see text] Equal-thickness screening is a critical part of mineral processing; recently, the multistage variable-inclination equal-thickness screen (MSVIETS) has been utilized in the mining industry across the world. In this work, a model of the collision mechanics between particles and the multistage variable-inclination screen surface was established. The maximum collision force (F(max)) was found to be closely related to amplitude, frequency, screen surface inclination, and number of stages. The time-frequency response characteristics of multistage (3-, 4-, and 5-STAGE) screen surfaces were studied by the vibration test analysis system. The permeation screen distribution law of grain groups on the screen surface was revealed. The obtained results show the best screening performance can be obtained from the 5-STAGE scheme with a screening efficiency of higher than 95% and total mismatch content of less than 2%. The synergistic mechanism between two of the parameters was revealed by Box–Behnken response surface methodology (BBRSM). Then, the correlation between the screening evaluation index and the multiple parameters was obtained, and the significant order of the parameters influencing the screening evaluation index was F(t) > f > n.