Linear vibrating screen is one of the main equipment in the crushing and screening process, and also the key equipment for providing qualified materials for subsequent operation. Its screening efficiency directly affects the subsequent operation. In the actual plant, the main factors affecting the screening efficiency of linear vibrating screen include material properties, screen surface structure parameters, vibration characteristics parameters and so on. Below, we will analyze how the above aspects affect the screening effect of linear vibrating screen.
First、 Material properties
The properties of the selected materials are one of the main factors affecting the screening efficiency of the linear vibrating screen, and the material properties are mainly reflected in the loose density, particle size and shape of the materials.
1. Loose density of selected materials
Generally, the loose density of materials is large and block particles, easy to pass through the screen, and the screening efficiency is high. On the contrary, the loose density of materials is small and the powder materials are not easy to pass through the screen, and they are easy to stay on the screen, which will limit or block the screen, so that the effective screening area of the sieve will be reduced, and the screening efficiency will be affected. In order to ensure the screening efficiency, the loose density of the selected materials should be controlled.
2. Selected material size
The particle size of selected materials is also an important factor affecting the screening efficiency of linear vibrating screen. The size of the particles of the materials entering the screen shall meet the size of the sieve hole. The size of the particles is small and easy to pass through the screen, and the size of the materials is not easy to pass through the screen. In order to ensure the screening efficiency, the particle size of the materials entering the screen shall be strictly controlled.
3. Shape of materials in sieve
The shape of the materials into the screen will affect the sieve property. Generally, the particles are full of grinding and the mineral particles with specifications are easy to pass through the screen. The irregular shape of the particles, such as long strip and sheet shape, is poor in screening rate. Therefore, it is necessary to ensure that the particle shape of the crushed material conforms to the sieve standard.
Second、 Screen surface structural parameters
The structural parameters of the linear vibrating screen are mainly reflected in the length and width of the screen surface and the size and shape of the screen.
1. Screen length and width
The length of screen surface of linear vibrating screen mainly affects the screening efficiency and the screen width affects productivity. The screen surface of straight screen is longer, the material stays on the screen surface for a long time, and the screening opportunity is more, which will improve the screening efficiency. In fact, the width of screen surface has different influence on screening efficiency and screen length on screening capacity.
The relationship between screening efficiency and the time of material on the whole screen is that at the beginning, the screening probability is higher. Because there are many fine-grained materials on the screen surface at the beginning, the screening probability is larger in unit time. After a certain time, the particle size of the materials left on the screen surface is mostly hard to screen materials close to the size of the screen. Even if the material stays on the screen surface for a long time (i.e. the length of the screen surface is large), it is difficult to increase the screening probability of the material, which leads to the decrease of the screen machine working efficiency. Therefore, the selection of the appropriate screen surface length can effectively improve the screening efficiency, and the ratio of the length to width of the straight screen surface is 1:2-1:3.
2. Shape and size of sieve
The selection of the shape of the sieve of the linear vibrating screen mainly depends on the screening granularity of the materials entering the screen and the product use under the screen. Compared with other shaped screens, the size of the materials passing through the circular sieve is smaller and the size of the materials passing through the rectangular sieve is larger. Therefore, in order to obtain higher screening efficiency, the different screening materials should be selected Same shape of sieve.
Third、 Vibration characteristic parameters
The vibration characteristic parameters of the linear vibrating screen include the inclination angle of screen surface, the direction angle of vibration, the amplitude and the vibration frequency.
1. Screen inclination
The inclination of the screen surface of the linear vibrating screen is related to the equipment processing capacity and screening efficiency. When the screen face inclination increases, the throwing strength of the material on the screen will increase, the material movement speed on the screen surface will increase, and the processing capacity of the vibrating screen will be increased. However, the retention time of the material on the screen is shorter, the material passing through the screen is less, and the screening efficiency is reduced. Otherwise, the processing capacity will be reduced and the screening will be reduced Efficiency is high.
In order to control the screening efficiency of the vibrating screen in a relatively ideal range, the inclination angle of the screen surface of the general linear vibrating screen is between 0 and 8 °.
2. Vibration direction angle
The angle between the vibration direction and the upper screen surface is called the vibration direction angle. The larger the vibration direction angle, the shorter the distance of mineral particles moving in each throwing movement, the slower the speed of moving on the screen surface, the more adequate the screening of materials, so the screening efficiency is higher. The smaller the vibration direction angle, the longer the distance of material moving forward on the screen surface when throwing, the shorter the time passing through the screen surface, the material can not be fully screened, so the screening efficiency is low. In order to ensure the screening efficiency of the linear vibrating screen, the range of the vibration direction angle is 30-60 ° is appropriate.
The amplitude of the linear vibrating screen determines the energy of the material particles moving on the screen surface. The larger the amplitude, the greater the amplitude of the material moving in the direction of the vertical screen surface during the screening process, the less the blockage of the screen, the more favorable the screening, the better the screening efficiency; otherwise, the screening efficiency is poor. Generally, the selection of amplitude is determined by the size and properties of the materials entering the screen. For materials with larger particle size, it is suitable to choose linear sieve with larger amplitude and lower frequency; for materials with smaller particle size, it is easy to select linear screen with smaller amplitude and higher frequency.
4. Vibration frequency
The vibration frequency of the screen surface of linear vibrating screen mainly affects the movement state of mineral particles, and the low or too high frequency is not conducive to the material passing through the sieve. The vibration frequency is too low, the probability of movement of mineral particles in the direction of vertical screen surface is small, and the screening rate is low; the vibration frequency is too high, and the vibration of mineral particles is easy to be confused, which affects the screening efficiency. Generally, the range of vibration frequency of the screen surface of the linear vibrating screen should be controlled within 15hz-30hz.
The above is the influence of the linear vibration screen screening efficiency of several aspects, if you want to effectively improve the screening efficiency of the linear vibrating screen, these aspects can not be ignored!
In the actual plant, each mineral has its own mineral characteristics, and has differences in density, hardness, gangue content, etc. Therefore, when selecting equipment, mineral processing test should be carried out first, and the suitable linear vibrating screen shall be selected through the test results, so as to ensure that all parameters of the equipment conform to the mineral particles.