Linear vibrating screen is a common screening equipment in mineral processing production, its screening efficiency has a certain impact on the final product quality and investment cost.
In the production, the factors affecting the screening efficiency of linear vibrating screen mainly include material properties, motion parameters, equipment performance, daily operation and management, etc. Below, let’s learn about the influence of various factors on the screening efficiency of linear vibrating screen, and explore how to improve the screening efficiency by changing these factors.
Use the table of contents below to navigate through the guide:
Usually, the material properties affecting the screening efficiency of linear vibrating screen mainly include the particle size, moisture, silt content, shape.
The "easy-to-screen particle ", "difficult-to-screen particle " and "obstruction" in the material have the obvious influence on the screening process of linear vibrating screen. In general, the more "easy-to-screen particle", the better the screening efficiency of linear vibrating screen. Because the "easy-to-screen particle" is easy to pass through the screen hole, so that the material on the screen is quickly reduced, thus greatly reducing the interference factors of difficult-to-screen particle.
There are three main kinds of material moisture mentioned here: first is the binding water closely combined with the material; Second is the adsorbed water widely exists in the pores and cracks of materials; Third is the external water attached to the surface of the material. In the dry screening process, the material moisture influencing the screening process of linear vibrating screen is mainly the third one. Therefore, when process the high-moisture materials, the operator can appropriately increase the mesh size to improve the screening efficiency of linear vibrating screen.
If the material contains the lumped clay-like minerals, the screening process can be difficult, even if the material has a low moisture content. Because a large number of fine materials will be mixed into the screen products after the clay mineral agglomeration, thus affecting the screening efficiency of linear vibrating screen. In addition, the agglomeration material is easy to block screen, and it is difficult to be removed once block screen. Therefore, it is recommended to spray water on the material moving along the screen surface, or finish the desliming or desliming before screening.
The influence of particle shape on the screening efficiency of linear vibrating screen mainly depends on the shape of the screen hole. For the square or circular mesh, the flat or rectangular material is more difficult to penetrate the screen, but the spherical, cubic and polygonal material can obtain the better screening efficiency.
The motion parameters affecting the screening efficiency of linear vibrating screen mainly include leaning angle of screen, direction angle of vibration, amplitude of screen, vibration frequency.
The leaning angle of screen mainly depends on the required processing capacity and screening efficiency. When other parameters are determined, the larger the leaning angle is, the higher the processing capacity is, but the lower the screening efficiency is.
■ Vibrating screen is used for screening the material (>50mm), the leaning angle of screen is generally 5-10°;
■ Vibrating screen is used for screening the medium and fine-grained material (<40mm), the leaning angle of screen is 0°;
■ Screen is used for dehydration, meshing and desliming, the leaning angle of screen is -5-0°;
For the linear vibrating screen, the direction angle of vibration is the projectile angle of the material. In the actual production, most of the linear vibrating screen adopt the direction angle of vibration as 30°, 45° and 60°, which can adapt to the various screening performance better, obtain the ideal moving speed and screening efficiency.
■ When the direction angle of vibration is 30-45°, the movement speed of material is fast, and the processing capacity is high, but the screening efficiency is not high, so it is suitable for processing the easy-to-screen material;
■ When the direction angle of vibration is 60°, the projectile angle of the material is large, the screening efficiency is high, but the processing capacity is not high, so it is suitable for processing difficult-to-screen materials.
According to the practice experience, the amplitude of the screen is related to the screen specifications, application and material size. In general, the single amplitude of the linear vibrating screen is 3.5-5.5mm, the larger the size of the vibrating screen, the greater the amplitude. When the linear vibrating screen is used for screening, the amplitude needs to be slightly larger, while the amplitude should be smaller when it used for dehydration and desliming. When the processing material granularity is large, the amplitude of the linear vibrating screen should also be increased.
The vibration frequency of the screen surface is related to the leaning angle of screen, direction angle of vibration and the amplitude of screen. At present, the vibration frequency of linear vibrating screen is generally 700-900rpm.
In terms of process performance, the factors affecting the screening efficiency of linear vibrating screen mainly refer to the structural parameters of the screen surface. When the feeding amount and screening conditions are certain, the width of the screen surface determines the processing capacity of the linear vibrating screen, and the length of the screen surface determines the screening efficiency of the linear vibrating screen.
Usually, the width of the screen surface of the linear vibrating screen is generally below 2.5m, and the width of the large linear vibrating screen can even reach 5.5m. But restricted by the structure of the screen frame and material strength, the width of the screen surface of the linear vibrating screen cannot be infinite, and the length also cannot be arbitrarily lengthened. In general, the better aspect ratio of the screen surface is 2-2.5.
In the daily operation, the linear vibrating screen needs to maintain uniform, continuous and appropriate feeding, ensuring that the material is evenly distributed along the width of the entire screen surface. It is conducive to the screening of fine particles, so as to obtain the higher processing capacity and screening efficiency.
In the daily maintenance, the operators need to pay the special attention to the fastening of the screen surface, and timely repair the detached paint skin, do a good job of maintenance and rust prevention of the linear vibrating screen surface, timely clean, repair and replace the damaged screen surface.
In addition, the linear vibrating screen operation personnel should be in accordance with the requirements of standards, rules, complete the equipment "three check in a day” maintenance work before starting, during the operation and after stopping. Once find problems and hidden dangers, the operation personnel should rule out in time, which can ensure the safe operation of the equipment in good condition and effectively control the maintenance cost of the equipment.
In order to improve the screening efficiency of linear vibrating screen, we need to master the material characteristics, accurately select the motion parameters and screen surface structural parameters, paying attention to the daily operation and maintenance management. Due to the difference in ore properties and the different requirements of the concentrator, the starting point of improving the linear vibrating screening efficiency is also different. It is suggested to seek the professional screening equipment manufacturers for consultation, thus obtaining the ideal screening efficiency.