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

Abstract

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 .

Air Classification of Crushed Materials

“…The red dotted line shows the line along which the speed of the incoming air flow was measured. They are determined in accordance with the fact that the constancy of Ψ along a certain line, according to (6), means that there is no air flow in a perpendicular direction. This condition is satisfied by the boundaries of the input channel and the surface of the classifier.…”

Particle Behavior and Aperture Optimization of Variable Vibration-Amplitude Screening Based on Discrete Element Method Simulation

“…Separation of particulate materials is commonly encountered in mineral processing. The classification of particle mixtures according to particle sizes is always a crucial procedure for subsequent processes. – Screening, or sieving, is the basic technology for the size classification of granular ores. – So far, various kinds of screening equipment have been invented for the grading of different granular materials. – In order to achieve uniform particle mass distribution on the screening equipment, which would yield better sieving performance at all screen panels and hence improve the overall efficiency, the concept of equal thickness screening was proposed. – This has been realized through two kinds of methods. One is to use variable inclination angles of the screen panels, such as the banana screens and sieve bends, , and the other is to use multiaxial excitation of screen panels with variable amplitudes, which has the advantages of low participating mass of the screen body but high throwing intensity .…”

“… 1 – 7 Screening, or sieving, is the basic technology for the size classification of granular ores. 8 – 10 So far, various kinds of screening equipment have been invented for the grading of different granular materials. 11 – 13 In order to achieve uniform particle mass distribution on the screening equipment, which would yield better sieving performance at all screen panels and hence improve the overall efficiency, the concept of equal thickness screening was proposed.…”