Variable elliptical vibrating screen: Particles kinematics and industrial application

Abstract

Traditional vibrating screen usually adopts the linear centralized excitation mode, which causes the difficulty in particles loosening and low screening efficiency. The variable elliptical vibrating screen (VEVS) trajectory is regulated to adapt the material mass along the direction of the screen length, improving the particles distribution as well as the screening efficiency. In this work, a theoretical model was developed for analyzing the screen surface motion law during VEVS-based screening process. An equation was obtained to show the relationship between the horizontal amplitude and the vertical amplitude. The materials kinetic characteristics were studied by using high-speed camera during screening process. Compared with equal-amplitude screen (EAS), the material moving velocity was increased by 13.03% on the first half but decreased by 3.52% on the second half, and the total screening time was reduced by 9.42% by using VEVS. In addition, −6 mm screening test was carried out. At the length of VEVS equaled to 1.2 m, the screening efficiency and the total misplaced material content were 92.50% and 2.90%, respectively. However, the screening efficiency was 89.91% and the total misplaced material content was 3.76% during EAS-based screening process. Furthermore, when external moisture is 5.96%, the screening efficiency of VEVS could reach 86.95%. The 2TKB50113 type VEVS with double-layered screen surface used in Huoshizui Coal Mine was 5.0 m in width and 11.3 m in length. The areas of single layer and double layer were 56.5 and 113 m2, respectively. In industrial production, the processing capacity was 2500–3000 t/h and the screening efficiency was larger than 90%.

Keywords

• Variable elliptical screen
• Thin-layer and equal thickness
• Particles kinematics
• Screen length
• Industrial application