The technical and economic indexes in the screening process of trommel screen are screening efficiency and productivity. The former is quality index, the latter is quantity index. They have relationship with each other, as well as have relation with a number of other factors. All thoes factors determine the final screening results.The factors which affect the screening process can be classified into three categories: 1.Physical properties of the screened material
Physical properties include the particle size composition, moisture content, mud content and particle shape of the material, etc.
The bigger the content of the fine particle content in the material,the higher the sieve productivity for the trommel screen. Generally speaking, the screening efficiency will be reduced when the material humidity is higher. However, the larger the mesh size, the smaller influence from the moisture.Therefore, for wet materials with large moisture content, in order to improve the screening process, we usually adopt the method of increasing the mesh size, or adopt wet screening. Wet screening or pre-washing should be used when the material has a high mud content (when the mud content is more than 8%).
2.Properties and structural parameters of screen surface
The trommel screen will with higher screening efficiency and larger production capacity if it makes particles move on the screen surface vertically. For same material, the screen productivity and screening efficiency is determined by the mesh size.The productivity is depends on the width of the screen surface, the bigger width of the screen surface, the higher productivity of the screen. The screening efficiency is depends on the length of the screen surface, the longer the length, the higher screening efficiency of the screen. The aspect ratio usually is 2.
The bigger the efficient surface,the higher the productivity and screening efficiency for per unit area.
The larger the mesh size, the higher the productivity of unit screen surface and the higher of the screening efficiency.
3.Production conditions of the trommel screen
The onsite production conditions of the trommel screen also affect the screening process of it greatly. When the load of the screen is large, the screening efficiency will be low. To a large extent, the screen productivity depends on the screen size and overall screening efficiency. For the same requirement for the screen efficiency, the bigger the screen, the bigger the productivity. In addition, the feed uniformity is also very important to the screening process. The more uniform the material feed,the higher the screening efficiency. The incline angle of the sieve should be suitable, which is generally determined by testing.Finally, the amplitude and shake frequency of the sieve, which is related to the trommel screen machine structure, in a certain range, increasing the vibration can improve the screening index.
Above are the main factors which affect the screening process of the trommel screen.Any assistance we can do,welcome to feel free to get in touch with us.