Improve the screening efficiency of linear vibrating screen from the following three aspects

Linear vibrating screen is one of the main equipment in the crushing and screening process, and is also a key equipment for providing qualified materials for subsequent operations. Its screening efficiency directly affects subsequent operations. In actual mills, the main factors affecting the screening efficiency of linear vibrating screens include: material properties, screen surface structure parameters, vibration characteristic parameters, etc. Below, we will specifically analyze how the above aspects affect the screening effect of linear vibrating screens.

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1、 Material properties

The properties of the selected materials are one of the main factors affecting the screening efficiency of the linear vibrating screen, and their properties are mainly reflected in the loose density, particle size, and shape of the materials.

(1). Selected material loose density

Generally, materials with high loose density and blocky particles are easy to pass through and have higher screening efficiency. Conversely, materials with low loose density and powdery materials are not easy to pass through the screen and are prone to remain on the screen, which can limit or block the sieve holes and reduce the effective screening area of the sieve, thereby affecting the screening efficiency. To ensure screening efficiency, it is necessary to control the loose density of the selected materials.

(2). Selected material particle size

Linear vibrating screen feeding

The particle size of the selected materials is also an important factor affecting the screening efficiency of the linear vibrating screen. The particle size of the screened materials should meet the size of the sieve hole. Small particles are easy to pass through, while large particles are not easy to pass through. To ensure screening efficiency, the particle size of the screened materials should be strictly controlled.

(3). Shape of incoming material

The shape of the material entering the screen will affect its sieving performance. Generally, mineral particles that are fully ground and of higher specifications are easy to pass through the screen, and the particle shape is irregular, such as elongated or sheet-like materials, resulting in poor sieving efficiency. Therefore, it is necessary to ensure that the particle shape of the crushed material meets the sieve hole standard.

2、 Sieve surface structural parameters

The structural parameters of a linear vibrating screen are mainly reflected in the length and width of the screen surface, as well as the size and shape of the screen holes.

(1). Screen surface length and width

The length of the screen surface of a linear vibrating screen mainly affects the screening efficiency, while the width of the screen surface mainly affects the productivity. The screen surface of a linear screen is longer, and the material stays on the screen surface for a longer time. There are more opportunities for sieving, which can improve the screening efficiency. In fact, the width of the screen surface has varying degrees of impact on the screening efficiency, and the length of the screen surface also has varying degrees of impact on the screening capacity.

The relationship between screening efficiency and the time that the material passes through the entire screening surface is that at the beginning, the probability of passing through the screen is higher. Because there is a large amount of fine-grained material on the screen surface at the beginning, the probability of passing through the screen per unit time is relatively high. After a certain period of time, the particle size of the material remaining on the screen surface is mostly difficult to screen, which is close to the size of the sieve hole. 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 probability of passing through the screen, resulting in a decrease in the efficiency of the screening machine. Therefore, selecting the appropriate length of the screen surface can effectively improve the screening efficiency, and the length to width ratio of the straight screen surface is generally 1:2~1:3.

(2). Mesh shape and size

The selection of the mesh shape of a linear vibrating screen mainly depends on the screening particle size of the incoming material and the purpose of the product under the screen. Compared with other shapes of mesh, circular mesh has a smaller particle size for the same material passing through the circular mesh, while rectangular mesh has a larger size for the screened material. Therefore, in order to achieve higher screening efficiency, different mesh shapes need to be selected for different screened materials.

3、 Vibration characteristic parameters

The vibration characteristic parameters of a linear vibrating screen include the inclination angle of the screen surface, vibration direction angle, amplitude, and vibration frequency.

(1). Screen surface inclination angle

The size of the inclination angle of the screen surface of a linear vibrating screen is related to the processing capacity and screening efficiency of the equipment. When the inclination angle of the screen surface increases, the throwing strength of the material on the screen will increase, and the movement speed of the material on the screen surface will increase, increasing the processing capacity of the vibrating screen. However, the residence time of the material on the screen is shorter, the chances of the material passing through the screen are fewer, and the screening efficiency is reduced. Conversely, the processing capacity will decrease, and the screening efficiency will be higher.

In order to control the screening efficiency of the vibrating screen within an ideal range, the inclination angle of the screen surface of the linear vibrating screen is generally between 0 and 8 °.

Linear vibrating screen surface inclination angle

(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 the mineral particles move during each throwing motion, and the slower the speed they move forward on the screen surface. The more thorough the screening of the material, the higher the screening efficiency. The smaller the vibration direction angle, the longer the distance the material moves forward on the screen surface when thrown, and the shorter the time it takes to pass through the screen surface, which prevents the material from being fully screened, resulting in lower screening efficiency. To ensure the screening efficiency of the linear vibrating screen, the appropriate range of vibration direction angle is 30-60 °.

(3). Amplitude

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's vertical movement in the direction of the screen surface during the screening process. The phenomenon of screen hole blockage will be reduced, which is more conducive to screening and the screening efficiency will be better; On the contrary, the screening efficiency is poor. Generally, the selection of amplitude is determined by the particle size and properties of the screened material. For materials with larger particle sizes, it is suitable to use linear screens with larger amplitudes and lower frequencies; For materials with finer particle size, it is easy to choose a linear screen with smaller amplitude and higher frequency.

(4). Vibration frequency

Linear vibrating screen vibration

The vibration frequency of the linear vibrating screen mainly affects the motion state of mineral particles. If the frequency is too low or too high, it is not conducive to the material passing through the sieve hole. If the vibration frequency is too low, the probability of mineral particles moving in the vertical direction of the screen surface is small, and the screening rate is low; The vibration frequency is too high, and the vibration of mineral particles is prone to confusion, which affects the screening efficiency. The vibration frequency range of the general linear vibrating screen should be controlled within 15Hz~30Hz.

The above are several major aspects that affect the screening efficiency of linear vibrating screens. If you want to effectively improve the screening efficiency of linear vibrating screens, these aspects cannot be ignored!

In actual beneficiation plants, each mineral has its own mineral characteristics, with differences in density, hardness, and gangue content. Therefore, when selecting equipment, beneficiation tests should be conducted first, and suitable linear vibrating screens should be selected based on the test results to ensure that the parameters of the equipment meet the particle size of the mineral.