How Can Screen Efficiency Be Improved?
The screening efficiency of the vibrating screen affects the subsequent operations in the production line. How can screen efficiency be improved is worthy of attention. There are many factors that affect the screening effect of the vibrating screen. The more important factors are the characteristics of the material, the screen surface parameters, and the motion parameters of the vibrating screen.
1. The characteristics of the material
The particle size and moisture content of the material directly affect the screening effect. When the particle size of the material is close to the mesh size, the screening efficiency will be significantly reduced. These particles will block the screen holes, resulting in a reduction in the effective screening area. When the water content of the material is large, the material is prone to adhesion, which reduces the screening efficiency.
A. Increase the vibrating screen amplitude. Increased amplitude can promote fine-grained materials to pass through the screen surface and reduce blockage.
B. Increase the pass rate of the middle part of the screen to improve the screening effect.
C. Change the feeding method to improve the utilization rate of the screen surface. Multi-channel feeding is used to reduce the movement time and distance of the material on the screen on the screen surface and improve the screening effect.
D. Enlarge the sieve holes to improve the screening effect of wet materials with high water content.
E. Use wet screening or pre-washing methods to process materials with mud content greater than 8%.
2. The screen surface parameters
The screen surface parameters of the vibrating screen include the shape of the vibrating screen mesh, the opening rate of the vibrating screen surface, and the material of the screen surface. Generally, long screen surface, long material residence time, many chances to penetrate the screen, and high efficiency. The wide screen surface has good processing capacity. Practice has proved that the appropriate ratio of screen surface aspect ratio is 2:1~3:1.
A. The opening rate of the screen surface refers to the effective screening area of the vibrating screen. The larger the effective sieve area, the higher the productivity per sieve surface, and the higher the screening efficiency.
B. The sieve shape is selected according to the particle shape of the material. Generally, it is better to use square sieve for sieving round particles.
C. Different screen surface materials can directly affect the adhesion coefficient between minerals and screen mesh. For viscous minerals, rubber, polyurethane and other flexible screen surface materials should be used to ensure that the material on the screen is loose. However, this type of material usually has the disadvantage of a smaller open porosity.
3. The screen surface parameters
The motion parameters of the vibrating screen include the vibration frequency and the direction angle of the vibrating screen.
The vibration causes the material on the screen surface to be thrown away from the screen surface, the coarse material reaches the upper layer of the material layer, and the fine material reaches the lower layer of the material layer. For materials with large particle sizes, generally the higher the frequency, the higher the number of bounces on the screen surface, the greater the chance of contact between the material and the screen surface, and the reduction of the occurrence of clogging of the screen holes. Therefore, an appropriate increase in the vibration frequency can effectively improve the screening effect.
The vibration direction angle is the angle between the vibration direction line and the screen surface. The larger the value of the angle, the smaller the horizontal movement distance of the material in the screening process, and the lower the relative movement speed on the screen. Through practice, the direction angle should be small for materials that are easy to sieve, and the direction angle should be large for materials that are difficult to sieve. Generally, the direction angle of the linear vibrating screen is between 30 degrees and 60 degrees, and the direction angle of the circular vibrating screen is 90 degrees.