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The three-deck vibrating screen can separate the material into various particle sizes. There are a few types of researchers on the screening efficiency and processing capacity of multideck vibrating screens. In this work, the discrete element method was used to simulate the screening process of the three-deck vibrating screen under different vibration parameters (frequency, amplitude, and inclination angle) and a prototype experiment was carried out. The effects of vibration parameters on the screening performance were analyzed based on the orthogonal design of experiments. An approximate model, the Kriging model, was used to replace the simulation process for further optimization. Then, an optimization algorithm conducted multiobjective optimization, and three sets of optimization solutions were obtained via a traversal approach. In addition, the three optimized vibration parameters were verified by simulation. There is a guideline for the design of vibration parameters of the multideck vibrating screen. [ABSTRACT FROM AUTHOR]

The three-dimensional structure model of unilateral driven swing screen was established by PROE software, and the load history on the eccentric shaft was obtained by dynamic simulation analysis. The stress distribution curve and stress cloud of the eccentric shaft were analyzed by using analytical method and finite element method. The analysis results show that the dangerous part of the eccentric shaft appears at the support of the intermediate bearing, and the maximum stress is about 35 MPa. The fatigue life (0.98 a) of the eccentric shaft was calculated by using the local stress-strain method, which can effectively prevent accident occurrence. These results provide a reliable basis for design and improvement of eccentric shafts.

The four-axis variable trajectory equal-thickness screen (FAVTETS) achieves equal-thickness screening by appropriate excitation force generated by four eccentric rotors in synchronized motion. The forced synchronization exciter is characterized by an unsatisfactory synchronization effect due to the wear of transmission parts. Hence, in this paper, the four-axis controlled synchronization of FAVTETS is investigated, and an intelligent control system is proposed. Firstly, research is conducted on the variable trajectory characteristics of FAVTETS. Next, the sliding mode, fuzzy, and PID controllers are designed and compared to obtain an ideal control effect. Moreover, the influence of torsional stiffness of flexible coupling on control accuracy is considered. The results show that the sliding mode controller has a good control effect. Based on the aforementioned, the simulation model of a four-axis controlled synchronization structure is established via MATLAB/Simulink. Finally, Labview is employed to design the four-axis controlled synchronization software system. Then, the physical experiment is carried out. The four-axis controlled synchronization and vibration trajectory measurement results verify the effectiveness and robustness of the intelligent control system. [ABSTRACT FROM AUTHOR]

Low-rank steam coal is an important coal resource, but has high water and ash content, which needs to be separated to improve its quality and calorific value. In this paper, the process of screening using a flip-flow screen and density separator using a shallow groove dense-medium separator for steam coal was proposed and applied to the Lijiahao coal preparation plant. Kinematics of the screen box and the surface of the flip-flow screen were investigated using an acceleration and laser displacement measurement and analysis system. The mechanism of the flip-flow screen to overcome aperture blocking and to enhance the screening performance for moist and fine coal was discussed. The results from an industrial experiment when screening at 3 mm showed that the screening efficiency was 82.51%, while the total misplaced materials were 5.91%. The commercial separation of a wide size range of coal using a shallow groove dense-medium separator was analyzed. The results showed that the system exhibited satisfactory separation performance for 100–3 mm coal, whereas the corresponding Ep value was found to be 0.06 g/cm3. Compared with the 6 mm separation system, the yield of clean coal increased by 8.50%, which remarkably increased the economic benefits for the company. [ABSTRACT FROM AUTHOR]

Elastic screening methods are widely used in the classification of moist coal as they can overcome the problem of aperture blockage. However, the use of an equally inclined screen surface with balanced excitation facilitates material accumulation, worsening the screening performance. Here, a disequilibrium excitation structure was proposed to solve the accumulation problem, and its synchronization process was studied using a high-speed camera system. The spatial motion of the rigid-flex elastic screen surface along material flow direction was reconstructed using a vibration test system. The influence of disequilibrium excitation force coefficient (Fde) and relative vibration motor shaft span (lvms) on the screening performance of moist coal was investigated. The results showed that the phase difference between the two eccentric rotors gradually decreased to 0 under the coupling effect of the electromechanical system, achieving synchronous stable operation. The spatial trajectories of different parts of the rigid-flex elastic screen surface were close to ellipsoidal, with the long axis of the ellipse decreasing along the direction of material flow. The screening efficiency showed a maximum and the total misplaced materials showed a minimum with increasing Fde and lvms. The optimum screening efficiency of 86.35% and the corresponding total misplaced materials of 5.03% were achieved at Fde = 1.15 and lvms = 40%. Compared to the equilibrium excitation structure, the elastic screening process was enhanced by the use of disequilibrium excitation, with the screening efficiency increasing by 3.20%. [ABSTRACT FROM AUTHOR]

Rigid-flex elastic screening methods are widely employed in the efficient utilization of moist coal as they have high efficiency. Here, the synergy between the total excitation force (Ft), frequency (f), and disequilibrium excitation force coefficient (Fde) on the disequilibrium excitation rigid-flex elastic screening process was investigated. The results showed that the order of significance of the investigated parameters on screening performance was: Ft > f > Fde. Mathematical correlation models for the screening efficiency (η) and total misplaced materials (Mo) were established, and were used to obtain the optimum parameter values of Ft = 6.81 kN, f = 14.10 Hz, and Fde = 1.16. Experiments were conducted on moist coal samples from different mines to validate the screening performance. It was found that for all three samples, η was > 85%, and Mo was < 4.90%, hence, the accuracy of the model was verified, and good screening performance was obtained. [ABSTRACT FROM AUTHOR]