Dynamic characteristics of an equal-thickness screen with a variable amplitude and screening analysis

Screening is the key unit in coal processing and utilization. Recently, equal-thickness screens characterized by a large capacity and high efficiency have been extensively used. Conventionally, equal-thickness screening is achieved by changing the inclinations of each stage or adjusting the exciting force. In this paper, a single-deck equal-thickness vibrating screen (ETVS) driven externally by an unbalanced two-axle excitation with a large span is proposed, and a set of dynamic equations governing the motion of the screen are also presented. The vibration data was obtained using a vibration test and analysis unit, and the bed stratification and particle behavior on the screen were obtained by image acquisition using a high-speed camera and data analysis unit. Screening experiments were conducted to evaluate the classification performance of the ETVS with a variable amplitude. The amplitude of the ETVS showed a decreasing trend, and a constant bed thickness was obtained throughout the screen deck. The ETVS has advantages of a high screen deck utilization and an efficient classification. Compared to the normal vibrating screen (NVS), the screening efficiency of the ETVS increased by 3.05%-8.76%. The screening performance of the ETVS is obviously better than that of the NVS, especially when dealing with a large amount of materials and those with high moisture. (C) 2017 Elsevier B.V. All rights reserved.