(1) If it is a circular vibrating screen, the simplest and most common reason is that the inclination of the screen is not enough. In practice, an inclination of 20 ° is the best. If the inclination angle is lower than 16 °, the material on the sieve will not move smoothly or will roll down;
(2) The drop between the coal chute and the screen surface is too small. The larger the coal drop, the greater the instantaneous impact force and the higher the sieving rate. If the distance between the chute and the sieve is too small, part of the coal will accumulate on the sieve because it cannot pass through the sieve quickly. Once the sieve is piled up, the sieving rate will be smaller and the oscillating quality of the sieve will also increase. An increase in the amount of sieve vibration will inevitably reduce the amplitude of the sieve, and a decrease in the amplitude will reduce the processing capacity of the sieve. In severe cases, the material pile will be pressed on the entire screen surface, causing the screen to fail to work. Generally, the drop of 400-500mm between the coal feed chute and the screen surface should be made;
(3) The width of the feed tank should be moderate. If it is overloaded, the material cannot be evenly distributed in the width direction of the screen surface, and the screening area cannot be used reasonably and effectively;
(4) Punching screen. When the coal is wet, the sieve will form a briquette and there will be almost no sieve. In this case, the punching screen can be changed to a welding screen.