Five processes of vibrating screen in coal preparation operations

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In recent years, with the improvement of the level of science and technology, people’s demand for goods has become more and more refined, and the quality has become higher and higher. The technology of vibrating screens also has higher requirements in the manufacturing industry. At the same time, with the development of the national economy, the screen Sub-technology and equipment are becoming more and more widely used in various industries.

Five processes of vibrating screen in coal preparation operations

In coal preparation operations, most of the vibrating screens are used to classify or dehydrate items. At the same time, in order to improve the accuracy of items, vibrating screens are often used to classify their items. In the coal industry, the role of vibrating screens is not only to classify, most of the vibrating screens are also used for dewatering or de-intermediation of coal, and even for desilting. In the coal preparation plant’s screening operations, raw coal preparation and product processing, it is mainly divided into five categories.

1. Prepare for sieving

Also called pre-screening. In the coal preparation plant, according to the requirements of the crushing operation and the sorting operation, the raw coal is screened into different particle sizes to prepare for the further work of the coal.

Arc vibrating screen

2. Dewatering and screening

Screening for the purpose of dehydration is used in the coal preparation plant for the dehydration of the processed products. The sieve used for the dehydration operation is called a dehydration sieve.

3. Desliming and screening

Screening for the purpose of removing slime. Desliming and screening is the operation of coal preparation plant in order to reduce the pollution of high ash fine sludge to clean coal. In the process of dewatering on the sieve, water jet washing is strengthened to remove part of the fine sludge. Desliming and screening are mostly used in heavy-medium coal preparation plants. In order to reduce the pollution of coal slime to the media system, desliming and screening should be used before coal enters the heavy-medium separator.

4. Screening for the purpose of removing heavy media

It is also called de-intermediate screening. It is a de-intermediate operation in which the product of heavy-medium coal preparation is sprayed with strong clean water on the sieve to separate the product from the heavier mass.

5. Slime recovery

It is screened for the purpose of recovering coal slime and used for dewatering of coal slime and tailings in coal preparation plants.

What is the reason for the incomplete dehydration of the high-frequency dehydration vibrating screen?

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As the name implies, the high-frequency dehydration vibrating screen can reduce the moisture in the material. Generally, it is widely used in the mining sand and gravel industry. The cleaned sand is then sent to the dewatering screen for secondary dehydration, which can reduce the mud content in the sand to the specified level. Degree. At present, it has good applicability for the screening and dehydration of fine sand, and it also plays an indispensable role. But if the high-frequency dewatering vibrating screen is not completely dehydrated, it must be reworked and will increase the screening workload. So what is the reason for the incomplete dewatering of the high-frequency dewatering vibrating screen? The following experienced vibrating screen manufacturers will answer this question for everyone.

Reasons for incomplete dehydration of high-frequency dehydration vibrating screen

High frequency dehydration vibrating screen

1. The reason for the screen

The dewatering screen is not tightened, and the transmission belt is too loose. The above two conditions are likely to cause incomplete dewatering, which is not conducive to the normal progress of the screening operation, and then affects the dewatering quality. In addition, the blockage of the sieve on the screen causes excessive load. More, it will also cause incomplete dehydration.

Solution: The screen should be tightened, and the transmission belt should be tightened; the screen surface should be cleaned in time.

2. The material layer on the screen is too thick

The over-thick material layer on the screen surface may be due to too much feed, or the above-mentioned sieve hole is blocked, which will cause the feed layer to be too thick, and then the dewatering screen will not work, so this is also the reason for the incomplete dewatering One. Greatly reduce the working efficiency of the screen machine.

Solution: Reduce the feed of the dewatering screen.

3. Reasons for material size

The vibrating dewatering screen material with a particle size smaller than 3/4 of the mesh size is easy to steal through the sieve, and is called easy sieve; the particle is larger than 3/4 of the sieve, and it is difficult to pass through the sieve. It is used for the special slurry dehydration of coal water slurry. The effect of the sieve is called particles that are difficult to sizing; particles with a particle size of 1-1.5 times the mesh size are called particles.

Solution: Screening contains a large number of finer materials of finer grades, and auxiliary screening methods can be added. The auxiliary sieve with a larger mesh size is used to pre-screen the grade of the product on the sieve. When used for the screening, dewatering and de-intermediation of finer materials, the equipment length of the screening machine is generally 5.6-7m, and the length ratio is about 3.

4. Uneven feeding of the sieve machine

Uneven feed will not only cause material accumulation and breakage, but too little feed will greatly reduce production efficiency, and too much accumulation will easily cause poor screening quality, and even cause equipment operation failure if it is serious.

Solution: The feeding of the screen machine should be adjusted to ensure uniform feeding.

5. Other reasons

(1) The horizontal level of the dewatering screen box is correct. Solution: adjust the height of the support; change the inclination angle of the screen box to increase the inclination angle;

(2) The steel support spring of the dewatering screen is too large or damaged. Solution: Adjust or replace the dewatering screen spring.

Precautions for the use of high-frequency dehydration vibrating screen

Arc vibrating screen

1. Pay attention to the smoothness of the bearing during the operation of the vibration motor of the dewatering screen. Under normal operating conditions, the accumulated operation time is about 1600 hours, the bearing grease should be replaced and the bearing, bearing chamber, and bearing gland should be cleaned.

2. After the dewatering screen is suspended or stored for more than half a year, the motor should be disassembled for maintenance and replaced with lubricating grease.

3. After the accumulated operation time of the dewatering screen exceeds 5000 hours, the motor bearing should be checked. If it is damaged, a new bearing should be replaced.

4. After the dewatering screen has been parked for half a year or for a long period of time, the insulation resistance of the motor stator coil to the ground should be measured before use. When measuring with a 500V megohmmeter, the insulation resistance should be no less than 20 megohms.

The above answers the question of what is the reason for the incomplete dehydration of the high-frequency dehydration vibrating screen. I hope it can be helpful to everyone. If there is a problem of incomplete dehydration during actual use, you can follow the reasons and solutions mentioned above. For inspection, if you really don’t know, you can contact the vibrating screen manufacturer purchased at that time for after-sales service.

What are the materials of the vibrating screen? Which material is better?

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As an important screening component of the vibrating screen, the screen is in direct contact with the material during the screening process, so the screen is the main vulnerable part in the vibrating screen system. Once the material is selected incorrectly, it is very easy to cause the screen to be worn and damaged, which affects normal production and increases the production cost. Therefore, if you want to choose the right vibrating screen, you must first understand the materials of the commonly used vibrating screens.

The material of the vibrating screen

1. Stainless steel screen

Stainless steel screen materials are mainly 201, 201, 302, 304, 304L, 316, etc., which have good acid resistance, alkali resistance, and rust resistance; high strength, tensile strength, toughness and wear resistance, durability, and high temperature oxidation resistance. , 304 stainless steel screen with a nominal temperature of 800 ℃, 310S stainless steel screen with a nominal temperature of 1150 ℃; normal temperature processing, that is, easy plastic processing, making the use of stainless steel screen diversified; high finish, no surface It is convenient and simple to handle and maintain. Stainless steel screens are often used for screening and filtering under acid and alkali environmental conditions, as well as mud screens in the petroleum industry, and screens in the chemical and chemical fiber industries.

2. High manganese steel screen

Among many materials, the quality of high manganese steel screen is relatively reliable. It is a kind of screen product woven by manganese steel mesh wire with a diameter of 1.6mm-12mm. It adopts embedded weaving method. The overlapping point of warp and weft is not prominent. The screen surface is flat and the force is even. Plasticity and toughness can achieve better results, while the service life is more guaranteed. High manganese steel has high strength, rigidity and bearing capacity. When subjected to strong impact and friction, the surface will produce strong work hardening due to plastic deformation, and the surface hardness can be increased to above HRC60, thereby obtaining high wear resistance. , While the interior still maintains high plasticity and toughness. In addition, when the old surface is worn out, the new surface will form a wear-resistant layer, so the service life can reach 4-8 times that of ordinary screens. It is mostly used in large-scale mining industries. It can also be used as a protective screen for mechanical vibrating screens, Drum screen machine, electromagnetic high frequency screen machine and asphalt mixing machine, etc.

3. Punching screen

Punching screen refers to the screen that uses a punch to punch out the target pattern in the plate to be processed. Generally, it is made of stainless steel, aluminum plate, cold and hot steel plate, copper plate, PVC film and other materials. The hole type is more selective and has long Holes, square holes, round holes, hexagonal holes, scale holes, stretched shaped holes, etc. Perforated screens have the characteristics of light weight, non-slip, beautiful appearance, and good filtering performance. They are often used in environmental protection noise control barriers in traffic and municipal facilities, and mine screens, mine screens, I-shaped screens, etc.

4. Polyurethane screen

Polyurethane screens are also easier to use and have better abrasion resistance. Polyurethane itself has very high elastic modulus, high strength and impact absorption, high wear resistance, and high tensile strength, so its bearing capacity is relatively high. It is more than 2.5 times that of rubber sieve plates, and its service life is 8-10 times longer than that of ordinary metal sieve plates, 3 times that of stainless steel screens, and 3.9 times that of natural rubber. It is the current screen material with better wear resistance. . The production material of the polyurethane screen is a polymer organic elastomer, which has excellent abrasion resistance, flexibility resistance, and large load-bearing capacity. It has been specially treated to ensure that it will never delaminate under long-term alternating loads.

5. Carbon steel screen

Vibrating screens made of carbon steel are rare. Although they are low in cost and have a certain degree of corrosion resistance, they have poor wear resistance and are not more stable than stainless steel and non-metallic materials. The amount of nickel is low, the material is hard, and it is easy to break, causing the screen of the vibrating screen to be damaged too quickly, so the application is relatively small.

The choice of vibrating screen

Arc vibrating screen

1. Choose according to materials

First of all, you must clarify what material you are sieving, and when you buy a vibrating screen. Then, according to the size of the sieved material particles, we can choose the sieve that can meet my needs for sieving. Describe the technical parameters of the screen mesh, wire diameter, aperture, diameter, material, effective screen surface, etc. The length unit is usually millimeters as the standard.

2. Choose according to the material

The material of several vibrating screens is introduced above, and the characteristics of each material are also explained in detail. Among the metal materials, the high-manganese steel screen is the better quality, but the cost is relatively high. Among non-metallic materials, polyurethane screens are the one that is easier to use.

3. Choose according to wear resistance

After clarifying the materials to be screened, look at the wear resistance of the screen. Because the materials screened by the mine vibrating screen often have higher strength, or in some chemical industries, the screened materials are corrosive, so the screen of the vibrating screen is required to have a certain degree of wear resistance, otherwise the screen Prone to breakage and high wear rate.

4. Choose according to the opening rate

The opening rate refers to the ratio of the area occupied by the screen holes to the area occupied by the screen surface. The larger the effective screening area, the greater the productivity per unit area of ​​the screen surface and the higher the screening efficiency; the opening rate of the screen surface It is an important parameter to measure the quality of the screen surface; it should be considered not to reduce the strength of the screen surface and significantly shorten the service life of the screen surface; the screen surface of the vibrating screen is evenly distributed with holes of a certain size and shape, which are commonly called sieve holes. ; When sieving materials on the screen surface, the materials passing through the sieve holes are called under-screen products, and the materials remaining on the screen surface are called over-screen products.

The installation steps of the vibrating screen

High frequency dehydration vibrating screen

1. Screen selection: Select the screen with the same mesh number. This is important. If the mesh number of the screen does not match, it will directly affect the accuracy and output of the screened materials;

2. Laying the screen: When installing the screen, the screen should be laid flat on the pallet, and the screen should be flattened as much as possible (but not too strong, otherwise it will affect the life and accuracy of the screen), and then use the fastening device to The screen is fixed on the net frame. Here to explain: Generally, the three-dimensional rotary vibrating screen frame is a letter grid frame. The screen mesh can be pressed on the mother mesh frame by a fastening device. The ultrasonic vibrating screen mesh is directly glued to the mesh frame, and only needs to be tightened and pasted during installation;

3. Fastening: After the screen is fastened to the mother frame, check whether the surrounding screens are all compressed on the mother frame. If slack is found, it should be adjusted reasonably;

4. Debugging: After the linear vibrating screen is installed, a little material should be used to test the cloth and screening of the screen. If the material is transported uniformly, and the classification is accurate, there is no mixing phenomenon, then it can be put into use; On the contrary, if there is unevenness such as deviation or accumulation, the flatness and uniformity of the screen surface of the screen should be adjusted; if there is a mixing phenomenon, the sealing of the linear vibrating screen and whether it is compressed should be checked.

The installation precautions of the vibrating screen

1. Note that you must choose a screen with a thicker wire diameter, because the installation of a linear screen is relatively cumbersome.

2. When cutting, the screen width should be the same as the net frame, and the length must be 50~70mm longer than the net frame.

3. When installing, the screen must be tensioned, because the tension of the screen is an important factor affecting the screening efficiency.

4. When installing the clear net pinball, you must pay attention to the difficulty of screening the material and the number of meshes, and it cannot be installed blindly.

5. If the specific gravity of the material is large or the mesh number of the screen is high, a suitable support mesh should be added under the screen. The purpose is to play a supporting role, reduce the pressure of the material on the screen, and prolong its service life. .

6. After the mesh frame is assembled to the screen box as required, remember to extend the grown screen into the corresponding outlet to avoid mixing.

7. When installing the pressure plate, be sure to pay attention to its flatness, and line it with a more flexible sponge sealing tape to evenly lock it, because this is the key to preventing mixing and an important factor that affects the service life of the screen.

The above is the introduction to the material of the vibrating screen. The material of the vibrating screen is a point that many users focus on when choosing a vibrating screen. When choosing a screen, it must be based on the characteristics of the material. The screen is wear-resistant. The combination of performance and opening rate is selected, so that the vibrating screen can also have a higher screening efficiency.

What are the process parameters of the vibrating screen? How to calculate?

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The vibrating screen generally has a harsh working environment, such as high temperature and high dust. In order to maintain the normal operation of the vibrating screen under this condition, it puts forward higher requirements on the process parameters of the vibrating screen. The process parameters of the vibrating screen are What? How to choose and calculate these parameters? All we need to understand. Reasonable process parameters can also ensure the normal operation of the vibrating screen, and in some respects also extend the service life of the screen.

Process parameters of vibrating screen

1. The inclination angle of the vibrating screen

The inclination angle of the screen surface refers to the angle between the screen surface of the vibrating screen and the horizontal line. The size of the inclination angle will affect the moving speed of the material on the drying surface. When the inclination angle of the screen surface is too large, the moving speed of the material will also increase. Although it can increase the production volume, it will reduce the screening efficiency. On the contrary, if the inclination angle is too small, the screening efficiency will be increased, but the production capacity will be reduced. Linear screens are generally installed horizontally with a zero inclination angle. Horizontal linear screens are generally only suitable for the screening of materials with a particle size of 40mm or less, or for the dehydration, desliming and removal of coal. If it is used for screening materials with a particle size of 50mm or more, the linear screen should have an angle, and the inclination angle is about 5º~10º.

2. Vibrating screen amplitude and frequency

Vibrating screen amplitude refers to the range and intensity of the box vibration, and frequency refers to the number of vibrations per minute of the screen box. When the amplitude is larger, the frequency of screening is higher, and the movement speed and acceleration of the screen box are also greater. When sieving coarse particles, it is recommended to adopt a larger amplitude and a lower frequency; conversely, when sieving fine particles, a smaller amplitude and a higher frequency should be maintained.

3. The length and width of the vibrating screen

When the other conditions of screening are the same, the productivity mainly depends on the width of the screen surface, and the screening efficiency is mainly determined by the length of the screen surface. But it does not mean that the width of the screen surface is as wide as possible, because when the screen surface is too wide, the feeding will be uneven and the rigidity will be poor. The screen surface is too long and can not increase the efficiency of screening, so the screen surface of the appropriate length and width should be selected. Therefore, the aspect ratio is generally 2:3. For the screening of coarse materials, the screen surface length is 3.5~4m. For the screening of medium and fine-grained materials, the screen surface length is 5~6m; the pre-screened screen surface can be shorter than the final screen surface It should be longer.

4. Throwing angle of vibrating screen

The throw angle of the vibrating screen refers to the angle formed between the direction of the box body and the screen surface when the box is moving, that is, the direction angle that the material on the screen surface is thrown by force. The larger the throwing angle, the slower the material movement speed, which will be adequately screened, which is suitable for difficult-to-screen materials. The smaller the projection angle, the faster the material movement speed, which is suitable for easy-to-screen materials.

Selection and calculation of vibrating screen parameters

1. Throwing index

According to experience, depending on the nature of the material to be processed, the theory and production practice for sieving have proved that the particle size is less than 3/4 of the mesh size, called “easy sieve”; the particle size is larger than the mesh size 3/ 4, called “difficult to sieve granules”; the closer the diameter of the granules is to the sieve size, the more difficult it is to penetrate the sieve. Most use medium-speed throwing index 1.75-3.3.

2. Installation inclination

The installation inclination angle is related to the processing capacity and screening efficiency of the vibrating screen.

(1) Material classification and separation, etc.: Installation angle=0°;

(2) Linear vibrating screen: dewatering: installation angle = 0°, negative if necessary; when the material is above 50 mm, the installation angle = 5~10°; when the material is below 40 mm: installation angle = 0°; For mud, de-intermediation, and dehydration: Installation angle = -5°~0°.

High frequency dehydration vibrating screen

3. Installation vibration direction angle

The value of linear vibrating screen is 30~60°, for linear vibrating screen, generally β=45°. The reason is that it has good adaptability, high movement speed and high productivity.

4. The length and width of the screen surface

Calculate the required area according to the actual production use of the sieve, productivity, and the particle size of the material to be screened. If it is a multi-layer screen, it should be calculated layer by layer, and the calculated peak value should be taken, and it should be rounded according to the standard.

(1) The length of the screen surface: below 3.6mm, the interval of each stage is 0.6m; above 3.6mm, the interval of each stage is 0.9m;

(2) Screen width: below 3.0mm, the interval of each step is 0.3m; above 3.0mm, the interval of each step is 0.6m.

5. Vibration tilt angle

The vibration tilt angle is usually 45°, and the tilt angle can be as high as 60° for some difficult-to-screen materials such as crushed stone, coke, and sinter.

6. The moving speed of the screen surface and the thickness of the material layer

The moving speed of the material along the screen surface is usually 0.12~0.4m/s, not more than 1.2m/s. For a circular vibrating screen, the moving speed of the material along the screen surface is related to the inclination angle of the screen surface. The relationship between the thickness δ of the material layer and the sieve size a is shown on the right: δ≤(3~4)a; the relationship between the thickness and the average particle size d0 of the material on the screen is shown on the right: δ≈(2~2.5)d0.

7. Vibrating screen amplitude and spindle speed

The amplitude is generally between 2~8mm. When the sieve is small or used for dehydration, take the small value. When the sieve hole is larger, choose a larger value. For the spindle speed, it can be calculated as follows:

Vibrating screen amplitude and spindle speed

A is the amplitude (mm); n is the spindle speed (n/min)

The above content summarizes what the process parameters of the vibrating screen are, such as the inclination of the screen surface, the amplitude and frequency, the length and width of the screen surface, etc. The vibrating screen obtains the ideal use effect.

Introduction to the working principle and structure of the linear vibrating screen

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Vibrating screen is a screening equipment used in the production of coal mines, building materials and other industries. According to different trajectories, vibrating screens can be divided into linear vibrating screens, circular vibrating screens, etc. Among them, the linear vibrating screen uses a vibrating motor as the vibration source, so that the material is thrown up on the screen and moves forward in a straight line. The feeder evenly enters the feed port of the sieving machine, and the oversieve and undersieve of several specifications are produced through the multi-layer screen and discharged from their respective outlets.

1. The working principle of linear vibrating screen

The working principle of the linear vibrating screen is that the shafts of the two vibrating machines have an inclination angle relative to the screen surface. Under the combined force of the exciting force and the material’s self-gravity, the material is thrown up and jumping forward on the screen surface to move forward in a straight line, so as to achieve the material Purpose of screening and grading.

The linear vibrating screen is driven by dual vibrating motors. When the two vibrating motors rotate synchronously and in opposite directions, the exciting force generated by the eccentric blocks cancels each other in the direction parallel to the motor axis, and stacks in the direction perpendicular to the motor axis. As a result, the trajectory of the screen is a straight line.

Screening process: After a large number of broken materials with different particle sizes and mixed coarse and fine particles enter the screen surface, only a part of the particles contact the screen surface. Due to the vibration of the screen box, the material layer on the screen is loosened, so that the gaps that exist in the large particles are removed. Further expansion, small particles take the opportunity to pass through the gap, transfer to the lower layer or conveyor. Because the gap between small particles is small and large particles cannot pass through, the original disorderly arrangement of particles separates, that is, they are stratified according to particle size, forming an arrangement rule with small particles on the bottom and coarse particles on the top.

Arc vibrating screen

2. Structural composition of linear vibrating screen

Linear vibrating screen is generally composed of vibrator, screen box, support or suspension device, transmission device and other parts.

1. Vibrating screen vibrator: single-shaft vibrating screen and double-shaft vibrating screen vibrators are distinguished by eccentric reconfiguration, and there are generally two types. The block eccentric type is better for the configuration of the eccentric weight.

2. Vibrating screen box: The screen box is composed of a screen frame, a screen surface and its pressing device. The screen frame is composed of side plates and beams. The screen frame must be sufficiently rigid. Mainly used to keep the screen flat and achieve normal screening. The screen box is the main part of the vibrating screen.

3. Vibrating screen supporting device: The supporting device of the vibrating screen has two types: hanging type and seat type. The seat type installation is relatively simple, and the installation height is low. In general, the seat type should be preferred. The supporting device of the vibrating screen is mainly composed of elastic elements. Commonly used are coil springs, plate springs and rubber springs.

4. Linear sieve damping spring: prevents vibration from being transmitted to the ground, while supporting the full weight of the screen box. When installed, the spring is perpendicular to the ground.

5. Vibrating screen transmission device: Vibrating screen usually adopts a V-belt transmission device. The structure of the vibrating screen is simple. The number of revolutions of the vibrator can be selected arbitrarily. However, the belt is easy to slip during operation. It may cause the sieve to be blocked. Vibrating screens are also directly driven by couplings. The coupling can maintain a stable number of revolutions of the vibrator. And it has a long service life. However, it is difficult to adjust the number of revolutions of the vibrator.

3. The characteristics of linear vibrating screen

（1）Using block eccentricity as excitation force, strong excitation force;

（2）The screen beam and the screen box adopt high-strength bolts, with simple structure and convenient and quick maintenance;

（3）Using tire coupling, flexible connection, stable operation;

（4）The structure of small amplitude, high frequency and large inclination angle makes the machine high in screening efficiency, long life, low power consumption and low noise;

（5）The design of the screen part can quickly change the screen and tension quickly. In addition, this design allows the use of various screens, such as nylon, special dragons, PP nets, etc.;

（6）The material has a long stroke on the screen surface, high screening accuracy and large processing capacity;

（7）At the same time of sorting, long-distance transportation of materials;

（8）The spacing and inclination of the screen surface can be changed according to the material size, the probability of penetrating the screen, and the productivity;

（9）Different shapes and structures can be designed according to the production site.

The above is an introduction to the working principle and structural composition of the linear vibrating screen. It can be seen that the motion track of the linear vibrating screen is a straight line, so the material is thrown up on the screen surface and moves forward in a straight line. Under the “cooperation” of gravity, materials can be screened and classified.

Linear vibrating screen is generally composed of vibrator, screen box, support or suspension device, transmission device and other parts. The vibrating screen produced by Hiside Heavy Industries has high strength, no welds, and built-in reinforcing ribs, which reduces the weight of the whole machine, while improving the rigidity of the screen machine, which is highly efficient and energy-saving.

For more information about the linear vibrating screen, please click to visit:

What are the sieve methods of linear vibrating screen?

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