good operation vibrating screen

operation and maintenance of vibrating screen

operation and maintenance of vibrating screen

This article suggests some ways to avoid the problems may occur in operation and maintenance, hope users could solve the concerning problems quickly and efficiently. 1. Overhaul the vibrating screen once a year. Replace the liner and repair screens. The vibration motor should be removed to check, and get the motor bearing for oil change. Replace the bearing if it is damaged. 2. Take out the sieve frame of vibrating screen regularly, check whether its surface is damaged or bumpy and whether the mesh is blocking. 3. Suggest making support frame to hang the spare screen. 4. Check the sealing trip of vibrating screen regularly, replace immediately when found wear or defect. 5. Check press device of sieve frame before use per shift, compress it when any loose. 6. Check the connection of feed box is loose or not per shift. If the gap is bigger and there is collision accident, the device will burst. 7. Check the support device of screen per shift, and inspect whether hollow rubber gasket is transformation or degumming. When the gasket is damaged or squashed, should replace two gaskets at the same time.

vibrating screen working principle

vibrating screen working principle

When the smaller rock has to be classified a vibrating screen will be used.The simplest Vibrating Screen Working Principle can be explained using the single deck screen and put it onto an inclined frame. The frame is mounted on springs. The vibration is generated from an unbalanced flywheel. A very erratic motion is developed when this wheel is rotated. You will find these simple screens in smaller operations and rock quarries where sizing isnt as critical. As the performance of this type of screen isnt good enough to meet the requirements of most mining operations two variations of this screen have been developed.

In the majority of cases, the types of screen decks that you will be operating will be either the horizontal screen or the inclined vibrating screen. The names of these screens do not reflect the angle that the screens are on, they reflect the direction of the motion that is creating the vibration.

An eccentric shaft is used in the inclined vibrating screen. There is an advantage of using this method of vibration generation over the unbalanced flywheel method first mentioned. The vibration of an unbalanced flywheel is very violent. This causes mechanical failure and structural damage to occur. The four-bearing system greatly reduces this problem. Why these screens are vibrated is to ensure that the ore comes into contact will the screen. By vibrating the screen the rock will be bounced around on top of it. This means, that by the time that the rock has traveled the length of the screen, it will have had the opportunity of hitting the screen mesh at just the right angle to be able to penetrate through it. If the rock is small enough it will be removed from the circuit. The large rock will, of course, be taken to the next stage in the process. Depending upon the tonnage and the size of the feed, there may be two sets of screens for each machine.

The reason for using two decks is to increase the surface area that the ore has to come into contact with. The top deck will have bigger holes in the grid of the screen. The size of the ore that it will be removed will be larger than that on the bottom. Only the small rock that is able to pass through the bottom screen will be removed from the circuit. In most cases the large rock that was on top of each screen will be mixed back together again.

The main cause of mechanical failure in screen decks is vibration. Even the frame, body, and bearings are affected by this. The larger the screen the bigger the effect. The vibration will crystallize the molecular structure of the metal causing what is known as METAL FATIGUE to develop. The first sign that an operator has indicated that the fatigue in the body of the screen deck is almost at a critical stage in its development are the hairline cracks that will appear around the vibrations point of origin. The bearings on the bigger screens have to be watched closer than most as they tend to fail suddenly. This is due to the vibration as well.

In plant design, it is usual to install a screen ahead of the secondary crusher to bypass any ore which has already been crushed small enough, and so to relieve it of unnecessary work. Very close screening is not required and some sort of moving bar or ring grizzly can well be used, but the modern method is to employ for the purpose a heavy-duty vibrating screen of the Hummer type which has no external moving parts to wear out ; the vibrator is totally enclosed and the only part subjected to wear is the surface of the screen.

The Hummer Screen, illustrated in Fig. 6, is the machine usually employed for the work, being designed for heavy and rough duty. It consists of a fixed frame, set on the slope, across which is tightly stretched a woven-wire screen composed of large diameter wires, or rods, of a special, hard-wearing alloy. A metal strip, bent over to the required angle, is fitted along the length of each side of the screen so that it can be secured to the frame at the correct tension by means of spring-loaded hook bolts. A vibrating mechanism attached to the middle of the screen imparts rapid vibrations of small amplitude to its surface, making the ore, which enters at the top, pass down it in an even mobile stream. The spring-loaded bolts, which can be seen in section in Fig. 7, movewith a hinge action, allowing unrestricted movement of the entire screening surface without transmitting the vibrations to the frame.

One, two, or three vibrators, depending on the length of the screen, are mounted across the frame and are connected through their armatures with a steel strip securely fixed down the middle of the screen. The powerful Type 50 Vibrator, used for heavy work, is shown in Fig. 7. The movement of the armature is directly controlled by the solenoid coil, which is connected by an external cable with a supply of 15-cycle single-phase alternating current ; this produces the alternating field in the coil that causes the up-and-down movement of the armature at the rate of thirty vibrations per second. At the end of every return stroke it hits a striking block and imparts to the screen a jerk which throws the larger pieces of ore to the top of the bed and gives the fine particles a better chance of passing through the meshes during the rest of the cycle. The motion can be regulated by spiral springs controlled by a handwheel, thus enabling the intensity of the vibrations to be adjusted within close limits. No lubrication is required either for the vibrating mechanism or for any other part of the screen, and the 15-cycle alternating current is usually supplied by a special motor-generator set placed somewhere where dust cannot reach it.

The Type 70 Screen is usually made 4 ft. wide and from 5 to 10 ft. in length. For the rough work described above it can be relied upon to give a capacity of 4 to 5 tons per square foot when screening to about in. and set at a slope of 25 to 30 degrees to the horizontal. The Type 50 Vibrator requires about 2 h.p. for its operation.

The determination of screen capacity is a very complex subject. There is a lot of theory on the subject that has been developed over many years of the manufacture of screens and much study of the results of their use. However, it is still necessary to test the results of a new installation to be reasonably certain of the screen capacity.

A general rule of thumb for good screening is that: The bed depth of material at the discharge end of a screen should never be over four times the size opening in the screen surface for material weighing 100 pounds per cubic foot or three times for material weighing 50 pounds per cubic foot. The feed end depth can be greater, particularly if the feed contains a large percentage of fines. Other interrelated factors are:

Vibration is produced on inclined screens by circular motion in a plane perpendicular to the screen with one-eighth to -in. amplitude at 700-1000 cycles per minute. The vibration lifts the material producing stratification. And with the screen on an incline, the material will cascade down the slope, introducing the probability that the particles will either pass through the screen openings or over their surface.

Screen capacity is dependent on the type, available area, and cleanliness of the screen and screenability of the aggregate. Belowis a general guide for determining screen capacity. The values may be used for dried aggregate where blinding (plugged screen openings), moisture build-up or other screening problems will not be encountered. In this table it is assumed that approximately 25% of the screen load is retained, for example, if the capacity of a screen is 100 tons/hr (tph) the approximate load on the screen would be 133 tph.

It is possible to not have enough material on a screen for it to be effective. For very small feed rates, the efficiency of a screen increases with increasing tonnage on the screen. The bed of oversize material on top of the marginal particlesstratification prevents them from bouncing around excessively, increases their number of attempts to get through the screen, and helps push them through. However, beyond an optimum point increasing tonnage on the screen causes a rather rapid decrease in the efficiency of the screen to serve its purpose.

Two common methods for calculating screen efficiency depend on whether the desired product is overs or throughs from the screen deck. If the oversize is considered to be the product, the screen operation should remove as much as possible of the undersize material. In that case, screen performance is based on the efficiency of undersize removal. When the throughs are considered to be the product, the operation should recover as much of the undersize material as possible. In that case, screen performance is based on the efficiency of undersize recovery.

These efficiency determinations necessitate taking a sample of the feed to the screen deck and one of the material that passes over the deck, that is, does not pass through it. These samples are subjected to sieve analysis tests to find the gradation of the materials. The results of these tests lead to the efficiencies. The equations for the screen efficiencies are as follows:

In both cases the amount of undersize material, which is included in the material that goes over the screen is relatively small. In Case 1 the undersize going over the screen is 19 10 = 9 tph, whereas in Case 2 the undersize going over is 55 50 = 5 tph. That would suggest that the efficiency of the screen in removing undersize material is nearly the same. However, it is the proportion of undersize material that is in the material going over the screen, that is, not passed through the screen, that determines the efficiency of the screen.

In the first cases the product is the oversize material fed to the screen and passed over it. And screen efficiency is based on how well the undersize material is removed from the overs. In other cases the undersize material fed to the screen, that is, the throughs, is considered the product. And the efficiency is dependent on how much of the undersize material is recovered in the throughs. This screen efficiency is determined by the Equation B above.An example using the case 1 situation for the throughs as the product gives a new case to consider for screen efficiency.

Generally, manufacturers of screening units of one, two, or three decks specify the many dimensions that may be of concern to the user, including the total headroom required for screen angles of 10-25 from the horizontal. Very few manufacturers show in their screen specifications the capacity to expect in tph per square foot of screen area. If they do indicate capacities for different screen openings, the bases are that the feed be granular free-flowing material with a unit weight of 100 lb/cu ft. Also the screen cloth will have 50% or more open area, 25% of total feed passing over the deck, 40% is half size, and screen efficiency is 90%. And all of those stipulations are for a one-deck unit with the deck at an 18 to 20 slope.

As was discussed with screen efficiencies, there will be some overs on the first passes that will contain undersize material but will not go through the screen. This material will continue recirculating until it passes through the screen. This is called the circulating load. By definition, circulating load equals the total feed to the crusher system with screens minus the new feed to the crusher. It is stated as a percentage of the new feed to the crusher. The equation for circulating load percentage is:

To help understand this determination and the equation use, take the example of 200 tph original or new material to the crusher. Assume 100% screen efficiency and 30% oversize in the crusher input. For the successive cycles of the circulating load:

The values for the circulating load percentages can be tabulated for various typical screen efficiencies and percents of oversize in the crusher product from one to 99%. This will expedite the determination for the circulating load in a closed Circuit crusher and screening system.

Among the key factors that have to be taken into account in determining the screen area required is the deck correction. A top deck should have a capacity as determined by trial and testing of the product output, but the capacity of each succeeding lower deck will be reduced by 10% because of the lower amount of oversize for stratification on the following decks. For example, the third deck would be 80% as effective as the top deck. Wash water or spray will increase the effectiveness of the screens with openings of less than 1 in. in size. In fact, a deck with water spray on 3/16 in. openings will be more than three times as effective as the same size without the water spray.

For efficient wet or dry screeningHi-capacity, 2-bearing design. Flywheel weights counterbalance eccentric shaft giving a true-circle motion to screen. Spring suspensions carry the weight. Bearings support only weight of shaft. Screen is free to float and follow positive screening motion without power-consuming friction losses. Saves up to 50% HP over4- bearing types. Sizes 1 x 2 to 6 x 14, single or double deck types, suspended or floor mounted units.Also Revolving (Trommel) Screens. For sizing, desliming or scrubbing. Sizes from 30 x 60 to 120.

TheVibrating Screen has rapidly come to the front as a leader in the sizing and dewatering of mining and industrial products. Its almost unlimited uses vary from the screening for size of crusher products to the accurate sizing of medicinal pellets. The Vibrating Screen is also used for wet sizing by operating the screen on an uphill slope, the lower end being under the surface of the liquid.

The main feature of the Vibrating Screen is the patented mechanism. In operation, the screen shaft rotates on two eccentrically mounted bearings, and this eccentric motion is transmitted into the screen body, causing a true circular throw motion, the radius of which is equivalent to the radius of eccentricity on the eccentric portion of the shaft. The simplicity of this construction allows the screen to be manufactured with a light weight but sturdy mechanism which is low in initial cost, low in maintenance and power costs, and yet has a high, positive capacity.

The Vibrating Screen is available in single and multiple deck units for floor mounting or suspension. The side panels are equipped with flanges containing precision punched bolt holes so that an additional deck may be added in the future by merely bolting the new deck either on the top or the bottom of the original deck. The advantage of this feature is that added capacity is gained without purchasing a separate mechanism, since the mechanisms originally furnished are designed for this feature. A positivemethod of maintaining proper screen tension is employed, the method depending on the wire diameter involved. Screen cloths are mounted on rubber covered camber bars, slightly arched for even distribution.

Standard screens are furnished with suspension rod or cable assemblies, or floor mounting brackets. Initial covering of standard steel screen cloth is included for separations down to 20 mesh. Suspension frame, fine mesh wire, and dust enclosure are furnished at a slight additional cost. Motor driven units include totally-enclosed, ball-bearing motors. The Vibrating Screen can be driven from either side. The driven sheave is included on units furnished without the drive.

The following table shows the many sizes available. Standard screens listed below are available in single and double deck units. The triple and quadruple deck units consist of double deck units with an additional deck or decks flanged to the original deck. Please consult our experienced staff of screening engineers for additional information and recommendations on your screening problems.

An extremely simple, positive method of imparting uniform vibration to the screen body. Using only two bearings and with no dead weight supported by them, the shaft is in effect floating on the two heavy-duty bearings.

The unit consists of the freely suspended screen body and a shaft assembly carried by the screen body. Near each end of the shaft, an eccentric portion is turned. The shaft is counterbalanced, by weighted fly-wheels, against the weight of the screen and loads that may be superimposed on it. When the shaft rotates, eccentric motion is transmitted from the eccentric portions, through the two bearings, to the screen frame.

The patented design of Dillon Vibrating Screens requires just two bearings instead of the four used in ordinary mechanical screens, resulting in simplicity of construction which cuts power cost in half for any screening job; reduces operating and maintenance costs.

With this simplified, lighter weight construction all power is put to useful work thus, the screen can operate at higher speeds when desired, giving greater screening capacity at lower power cost. The sting of the positive, high speed vibration eliminates blinding of screen openings.

The sketches below demonstrate the four standard methods of fastening a screen cloth to the Dillon Screen. The choice of method is generally dependent on screen wire diameters. It is recommended that the following guide be followed:

Before Separation can take place we need to get the fine particles to the bottom of the pile next to the screen deck openings and the coarse particles to the top. Without this phenomenon, we would have all the big particles blocking the openings with the fines resting atop of them and never going through.

We need to state that 100% efficiency, that is, putting every undersize particle through and every oversize particle over, is impossible. If you put 95% of the undersize pieces through we in the screen business call that commercially perfect.

how to solve the problems of linear vibrating screen

how to solve the problems of linear vibrating screen

Linear vibrating screen is one of the most important screening machines in mining and coal industries. However, linear vibrating screen always happens some troubles in operation because of the influence of production conditions. There are some resolutions for common troubles for customers reference. 1. The fluidity of coal on screen is not good in operation, or linear vibrating screen happens swing and vibrating will effect the service life of spring. The solution for the problem is that adjust the position of eccentric wheel if blocking in head section or tail section, and add weight of eccentric wheel when blocking in middle section. In addition, the improper position of wash pipe used for classification or dehydration will cause the coal blocking on screen. In that case, adjust the position of wash pipe properly to bring materials up to speed. However, the method is suitable for materials in 0-3mm only. 2. The bearing blocks of linear vibrating screen are easy to shatter, and the bearings easy to heat damage while bottom beam easy to fracture caused by too heavy weight increases the exciting force and amplitude of screen. Solve the said problem can by reducing the weight of eccentric wheel, replacing springs with higher stiffness, replacing different type bearing, or changing the strength of spring. Meanwhile, strengthening the bottom beam can also extend machines service life. 3. The amplitude of linear vibrating screen may be lower than the parameter designed caused by various factors. Lower amplitude may reduce processing capacity of screen, and higher amplitude would reduce the service life of bearing blocks, bearings and bottom beam. In general, changing the wight of eccentric wheel or selecting springs with different strength according to specific situation can adjust amplitude of the machine to meet the need of the production.

Linear vibrating screen is one of the most important screening machines in mining and coal industries. However, linear vibrating screen always happens some troubles in operation because of the influence of production conditions. There are some resolutions for common troubles for customers reference.

1. The fluidity of coal on screen is not good in operation, or linear vibrating screen happens swing and vibrating will effect the service life of spring. The solution for the problem is that adjust the position of eccentric wheel if blocking in head section or tail section, and add weight of eccentric wheel when blocking in middle section.

In addition, the improper position of wash pipe used for classification or dehydration will cause the coal blocking on screen. In that case, adjust the position of wash pipe properly to bring materials up to speed. However, the method is suitable for materials in 0-3mm only.

2. The bearing blocks of linear vibrating screen are easy to shatter, and the bearings easy to heat damage while bottom beam easy to fracture caused by too heavy weight increases the exciting force and amplitude of screen. Solve the said problem can by reducing the weight of eccentric wheel, replacing springs with higher stiffness, replacing different type bearing, or changing the strength of spring. Meanwhile, strengthening the bottom beam can also extend machines service life.

3. The amplitude of linear vibrating screen may be lower than the parameter designed caused by various factors. Lower amplitude may reduce processing capacity of screen, and higher amplitude would reduce the service life of bearing blocks, bearings and bottom beam. In general, changing the wight of eccentric wheel or selecting springs with different strength according to specific situation can adjust amplitude of the machine to meet the need of the production.

vibrating screen - mineral processing

vibrating screen - mineral processing

Separate crushed materials and gravel into different sizes through large screens or industrial screens. As part of the crushing operation, coarse screens called grizzly bears or oxen are used to separate too large or too small materials from raw materials.Screens have static, horizontal and cylindrical screens, but today, most factories use inclined vibrating screens. The screening equipment determines the clear and reliable material separation, which provides the basis for the subsequent mineral processing.

Main parts of high frequency vibrating screen are mainframe, screen, electric vibrators, electric motor, rub spring and coupler.The screening decks are capable of single to triple decks, greatly improve the screening efficiency and capacity. Besides, providing a thin and loose bed of particles, which as well as do a good effect on the screen.Sieving is one of the oldest and most widely used physical size separation methods and is widely used in industry. In the continuous screening process, high frequency and low amplitude features lead to the vertical elliptical movement, the particles that fall from the feed hopper and reach the surface of the screen are sorted under the action of gravity. Oversized particles rebound along the screen, and most undersized particles pass through the holes.

High frequency vibrating screen is the most important screening machine mainly used in the beneficiation industry. They are used to separate materials containing solids and crushed ores with a particle size of less than 200 m. Wetting or drying materials can be sieved.Unlike the ordinary vibrating screen, the frequency of high-frequency screening is controlled by an electromagnetic vibrator installed above the surface of the screen and directly connected to the surface of the screen, and the vibration frequency is adjustable.High-frequency vibrating screens are usually operated at an angle of inclination, traditionally varying between 0 and 25 degrees, up to 45 degrees. In addition, it should operate at a low stroke with a frequency range of 1500-7200 RPM. Before using a high-frequency screen, it is usually necessary to pretreat the feed, because the holes in the screen are easily blocked.

The limitation of the high frequency vibrating screen is that the fine screen is very fragile and easily blocked. As time goes by, the separation efficiency will decrease and the screen needs to be replaced.

Circular vibrating screenThe multi-layer vibrating screen is specially designed for screening stones in quarries. It can also be used to classify products in coal preparation, mineral processing, building material production, power and chemical industries.The main advantages of the circular vibrating screen are as follows.(1) By adjusting the excitation force, the flow rate can be changed easily and steadily.(2) The circular vibrating screen has stable vibration, reliable operation and long service life.(3) Simple structure and reliable operation. The relatively light weight and small volume make maintenance easier.(4) The closed structure of the screen effectively prevents dust pollution.(5) Low noise intensity and small power consumption are generated during the operation of the vibrating screen.High frequency vibrating screen(1) Light, durable structure. The compact high-power vibration exciter is used as the drive. No belt or other accessories are required. The screen is very light but durable.(2) Adjustable flow rate. The screening capacity can be adjusted with ease because the stroke can be varied by adjusting the unbalanced weight with the most suited number of poles.(3) Screening capacity can be easily adjusted by adjusting the stroke, frequency, etc.(4) Stable performance. The high power of vibration makes screen run stable, even when screening adhesive materials.(5) Accurate screening. According to the specific materials and flow rate, single-layer to triple-layer deck-type groove can be designed according to the screening requirements to achieve accurate and efficient screening.(6) Simple start, stop. Press the controller button to easily control the start or stop of screening.

In the beneficiation line of various ores, the high-frequency sieve plays a vital role. The high-frequency sieve sifts out the coarse particles and sends them back to the crusher for crushing. At the same time, the fine-grained materials are discharged in time to avoid excessive crushing caused by re-grinding.The sieved materials can enter the next stage of beneficiation process. The use of high-frequency sieve can not only meet the requirements of mineral fineness, but also achieve smaller particle size separation, thereby reducing the capacity and overall energy consumption required in the crushing stage. Therefore, the grade of the final product is improved, and a better recovery rate and screening efficiency are provided.

which one benefits you most? vibrating screen or trommel screen? | fote machinery

which one benefits you most? vibrating screen or trommel screen? | fote machinery

Drum screen, with large volume, is a cylinder. It mainly consists of the motor, reducer, drum device, screen, frame, sealing cover, inlet and outlet. The drum device must be equipped with a steel ring to prevent the deformation of the drum screen.

It is widely used in the screening of raw coal, crushed stone and other materials in alumina plants, power plants, coking plants, cement, mining, metallurgy, building materials, coal chemical industries, etc. It is key screening equipment in the coal chemical industry.

Linear screens mainly screen fine particles with light specific gravity and low-hardness, mainly dry materials. They are usually used in food, chemical, building materials, and pharmaceutical industries.

When the materials are fed into the drum screen, due to its tilt and rotation, qualified materials (undersize product) are discharged through the discharging port at the bottom of the rear end of the drum, while unqualified materials (oversize product) are discharged through the other discharge port.

The linear vibrating screen adopts a vibrating motor as the vibration source, so the material is thrown up on the screen. Then several specifications of undersize products and oversize products are produced through the multi-layer screen. Finally, they are discharged from their respective outlets.

Generally, the inclination of the drum screen is 5-30. It is generally close to 30 for light and fine materials. When the material is heavier, it can be less than 20, and in special cases, 5-10.

The inclination of the circular vibrating screen is suitable when it is 20, and the general range is between 16-20. If the inclination angle is less than 16, the material on the screen may not move smoothly or roll upward.

The vibrating screen is screening equipment with a vibrating motor as the vibration source, so its screening accuracy is high. The trommel screen is high-output screening equipment with the screening accuracy not as high as the vibrating screen.

As for the circular vibrating screen, the material moves in a parabolic circular trajectory on the screen surface, so the material is dispersed as much as possible to improve the material's bounce force.

As a leading mining machinery manufacturer and exporter in China, we are always here to provide you with high quality products and better services. Welcome to contact us through one of the following ways or visit our company and factories.

Based on the high quality and complete after-sales service, our products have been exported to more than 120 countries and regions. Fote Machinery has been the choice of more than 200,000 customers.

five parameters affect screening efficiency of vibrating screen - xinhai

five parameters affect screening efficiency of vibrating screen - xinhai

In the mineral processing production, many mine owners may have met various problems, like the vibrating screen cannot reach the expected processing capacity, the screening efficiency is too low. As important screening equipment, the screening efficiency of the vibrating screen will directly affect the final product quality and investment cost.

Generally, the screening efficiency of vibrating screen is related to many factors, such as material properties, equipment structure and various performance parameters. In addition to the hard factors of material properties and equipment structure, we mainly start from the performance parameters and analyze the influence of each performance parameters on the screening efficiency of vibrating screen, including amplitude, vibration frequency, vibration direction angle, screen surface inclination angle and projectile angle, so as to provide a reference for vibrating screen operators.

Generally, the larger model the vibrating screen, the larger the selected amplitude. If the amplitude of the vibrating screen is larger, the phenomenon of screen hole blockage will be less, which is more conducive to the screening of ore stratification, and obtain better screening production capacity. However, it should be noted that if the amplitude of the vibrating screen is too large, the strong vibration will cause relatively large damage to the vibrating screen itself. The vibration screen amplitude selection is usually determined by the ore size and properties, when the ore particles are small, wet and also have a certain viscosity, we need to use low frequency, large amplitude.

In addition, the corresponding amplitudes and frequencies should be selected for different screening stages. For example, the screening operations used before the separation generally use low frequency, the large amplitude of vibration, dehydration, the disintermediation operations generally uses high frequency, small amplitude.

The vibration frequency has a direct influence on the pulsation state of ore particles on the screen surface. Taking high frequency vibrating screen as an example, its high frequency can well break the tension of pulp surface, makes fine material oscillate at high speed on the screen surface, accelerates the separation of useful minerals, and increases the probability of contact between material with less than separated particle size and sieve hole, thus creating good screening conditions. Too high or too low vibration frequency is not beneficial to screening efficiency vibrating screen.

According to the study, no matter what screening operation the vibrating screen carries out, the vibration frequency is maintained at 850-1000 times/minute as an ideal choice. If the frequency is too low and the vibration intensity is the same, the weight of the eccentric block of the vibrator will increase accordingly, which is not economical enough. At the same vibration intensity, the higher frequency will greatly affect the running speed of the ore, which means that the processing capacity is reduced. Therefore, the vibration frequency is not adjusted at will, must be adjusted to the appropriate range according to the actual situation of the selection plant to make the vibrating screen play the ideal performance.

Slope angle of screen surface refers to the included angle between screen surface and horizontal plane. The size of its angle is closely related to the processing capacity and screening efficiency of the vibrating screen. When the inclination angle of the screen surface increases, the movement speed of ore particles on the screen surface becomes faster, and the processing capacity increases accordingly. However, the residence time of ore particles on the screen surface is correspondingly shorter at the same time, which affects the screening efficiency of the vibrating screen.

The slope angle of screen surface is determined according to the material application and actual production needs. The horizontal vibrating screen is recommended for fine screening. If the granularity of screening material is large and the screening rate is good, the slope angle can adopt 5-10. If the particles are large and overgrinding, the slope angle can adopt 15. The reasonable range of slope angle is based on the uniform distribution of material particles. Installation inclination of different types of vibrating screen is different, the installation inclination of high frequency vibrating screen is about 30, the inclination of vibrating screen used for the general purpose is 0-15.

The vibration direction angle mentioned here refers to the included angle between the screen motion direction and the screen surface, which is generally denoted by . When determining the vibrating direction angle, the first thing should be considered is the nature of the ore being screened. For the ore with high density or fine particle size, easy to be crushed, the vibrating direction angle of the vibrating screen should be large. For those minerals with large water content, strong viscosity or abrasion resistance, the vibrating direction angle of the vibrating screen should be small.

In actual production, most linear vibrating screen adopt the vibrating direction angle as 30, 45 and 60, which can not only better adapt to various screening performance, but also obtain the best moving speed and screening efficiency. The vibrating direction angle of the circular vibrating screen is 90, so the circular vibrating screen needs to be installed at an angle, otherwise the minerals will not move forward.

According to the screening theory and practice, the size and strength of the projection angle of the vibrating screen have a direct influence on the screening of the ore on the screen surface. When the projection strength of the vibrating screen of ore increases, the inertial force is also larger, the ore can be thrown higher, which is more conducive to the screening. However, too much projection strength will inevitably affect the screen box, making it premature damage. Therefore, the size and strength of the projection angle should consider the structural strength of the screen box.

In the actual use of the process, different types of vibrating screen will certainly have some differences. It is suggested that all mine owners look for equipment manufacturers with the qualification of mineral processing EPC+M+O service to purchase the appropriate vibrating screen, and determine the value of each parameter according to the actual situation of the mineral processing plant, so as to obtain the ideal screening efficiency of the vibrating screen.

vibrating screen machines

vibrating screen machines

These vibration screens can be used for literally anything.Before designing and eventually manufacturing your screening machine we would need details regarding the material you would like to screen. Such as wet or dry.

It is one version of mechanical screening process. They call it linear as the machine generates a linear motion. Within this linear vibrating motion the motors make the material pop up and down. Although these linear screening machines made to specific customer's needs they are usually fitted with double vibrating motors. If it required we are more than happy to install more and/or higher power rating motors. It all depends what material has to be screened. Both the vibrating movement and the gravity force ensure that the material graded efficiently through the screening mesh.

These vibratory screens have a wide range of use depending on application. We offer a tailor-made solution . Linear vibrating screens can have one or multiple decks. It can be 3-4 meter wide and several meter long according to your requirements. They are quite simple to operate and clean. Maintenance doesn't take longer than few minutes. The screening mesh we install is vital part of the machine. We tirelessly work on the developments of our machines which have allowed us to develop a durable net system which can handle the roughest materials. Using our net the screening mesh

won't get thorn by the roughest materials. Its fully enclosed structure and automated layout is suitable for any pipeline type operations. The machine's screening box fitted with copper inserts and all these sections are welded together. Each sections of the machine are bolted together to its supporting frame. It is used to remove contaminants, lumps to improve the quality of the final product. To be used to separate variety of materials such as grains, potatoes, chips, mineral, cement or concrete industry. We have produced several linear vibrating machine for coal industry.

In general rotary vibrating screens enables you to filter/screen any (dry or wet) material. In order to achieve the highest efficiency we would need to know details of the material. Commonly used materials are soil, mud, stone, grains ceramic products or any PVC, nylon based material. Screened materials' shape doesn't have to me symmetric or sharp-edged. Multiple drums can be fitted together depending on required sieving efficiency. These drums and sieve screens inside can separate various types of granular material eg. a group of grains.

Although drum screens are known by low efficiency in grain separation it is usually down to poor sieve movement inside the drum. It is well known problem that vibrating sieve holes tend to clog. Our company put enormous effort to improve this lower efficiency and our study shows that by choosing the right sieve design these sieve holes become unblocked without dismantling the drum.

We can manufacture both flat and cone-shaped sieves for your requirements but by our experience and by some other studies show that sieve holes blocking is more significant with a cone type sieve than in the flat-shape vibrating screen. We highly recommend you to go with the flat rotary vibrating screen design.

Material classification can be achieved by large variety of sieve types. Sharp edged materials unfortunately lead to lower screening efficiency. We not just follow the technological improvements of these screening methods but we also try to lead the market using our revolutionary ways in screening processes. If you would like to choose rotary screen design we recommend you to use the optimal 20 and 28 (the sieve inclination) angle according to the study by Katarzyna Lawinska (Lodz University of Technology, Poland). We also use their recommended 0.6 RPM for the sieve rotational speed. Using these recommended values we achieve the best efficiency by having less blocked sieve holes. Contact us for advice regarding design.

pulp screening | vibrating screen | pressure screen

pulp screening | vibrating screen | pressure screen

The purpose of pulp screening is to remove the impurities to meet quality and normal production needs. Fibrous impurities include: wood chips, green sheets, grass joints, crude fiber bundles, and non-fibrous cells. Non-fibrous impurities include: sand, iron filings, crushed stone, cinder, and the like. The pulp screening requirements are high efficiency of screening and purification, less loss of tail slag, simple equipment flow, convenient operation and maintenance, and low power consumption.

The basic principle of screening is to use the static or dynamic pressure difference inside and outside the screen to separate according to the geometry of the impurities. The prerequisites and necessary conditions for screening: the pulp shall be fully diluted to make it free; the fiber layer is formed and destroyed (vibration or pulse)

Frame vibrating flat screen is the screening equipment that destroys the fiber layer formed on the screen plate through the vibration. And the fiber passes through the screen slots continuously. Screening is that the fiber forms on the plate and interfered by the vibration continuously. After the pulp is digested, the knots, green sheets, wood strips, and crude impurities such as sand and stone chips entrained with raw materials are removed in order to protect the equipment in the next step. This series of equipments have the advantages of high knotting capacity, low power consumption and small occupied area. It is one of the ideal screening equipment for coarse pulp.

Pressure screen adopts the upward flow structure design of the bottom feeding, the bottom discharge of heavy slag and the top discharge of light slag. The light impurities and the air in the pulp rise to the top for slag discharge naturally, and the heavy impurities can fall down to the bottom as soon as they enter the equipment.

The working principle of the pressure screen is that the pulp enters a certain pressure screen in a tangential direction with a certain pressure. At each moment between the rotor and the drum, a positive pressure zone is formed in the front part of the rotor, a balance zone in the middle part, a negative pressure zone in the tail part, and a screen drum in the negative pressure zone. The outer good pulp is washed back and plays the role of self-cleaning to keep the screen slot unblocked. When the pulp leaves the wing tail, the negative pressure disappears, and the good pulp is driven by another rotor to flow out again, starting the next cycle. The slag falls into the lower part and is discharged through slag valve.

Pressure screen is divided into an inner flow screen and an outer flow screen according to different directions of pulp in the screen. According to the shape of the drum, it can be divided into round screen and slot screen. The slot screen can be further divided into smooth slot flat screen and slot wave screen. Nowadays, the slot wave screen is widely used.

Pulp screening is an essential working process in the high-value pulp production. Pulping producers have gotten increasingly reliable for pulp screening because of its efficiency, reliability and cost.

Pulp is a lignocellulosic fibrous material prepared by chemically or mechanically separating cellulose fibres from wood, fiber crops, waste paper, or rags. Many kinds of paper are made from wood with nothing else mixed into them. This includes newspapers, magazines and even toilet paper. Pulp is one of the most abundant raw materials.

A pulp mill is a manufacturing facility that converts wood chips or other plant fibre source into a thick fibre board which can be shipped to a paper mill for further processing. Pulp can be manufactured using mechanical, semi-chemical or fully chemical methods (kraft and sulfite processes). The finished product may be either bleached or non-bleached, depending on the customer requirements.

A paper machine (or paper-making machine) is an industrial machine which is used in the pulp and paper industry to create paper in large quantities at high speed. Modern paper-making machines are based on the principles of the Fourdrinier Machine, which uses a moving woven mesh to create a continuous paper web by filtering out the fibres held in a paper stock and producing a continuously moving wet mat of fibre. This is dried in the machine to produce a strong paper web.

The pulp produced up to this point in the process can be bleached to produce a white paper product. The chemicals used to bleach pulp have been a source of environmental concern, and recently the pulp industry has been using alternatives to chlorine, such as chlorine dioxide, oxygen, ozone and hydrogen peroxide.

Chemical pulp is produced by combining wood chips and chemicals in large vessels called digesters. There, heat and chemicals break down lignin, which binds cellulose fibres together, without seriously degrading the cellulose fibres. Chemical pulp is used for materials that need to be stronger or combined with mechanical pulps to give a product different characteristics. The kraft process is the dominant chemical pulping method, with the sulfite process second. Historically soda pulping was the first successful chemical pulping method.

performance optimization of banana vibrating screens based on pso-svr under dem simulations | jve journals

performance optimization of banana vibrating screens based on pso-svr under dem simulations | jve journals

Journal of Vibroengineering, Vol. 21, Issue 1, 2019, p. 28-39. https://doi.org/10.21595/jve.2018.19543 Received 18 December 2017; received in revised form 16 August 2018; accepted 23 August 2018; published 15 February 2019

Li Zhanfu, Li Kunyuan, Ge Xiaole, Tong Xin Performance optimization of banana vibrating screens based on PSO-SVR under DEM simulations. Journal of Vibroengineering, Vol. 21, Issue 1, 2019, p. 28-39. https://doi.org/10.21595/jve.2018.19543

This paper carried out the numerical simulation about the movement of non-spherical particles on banana vibrating screen using direct element method (DEM) considering the complexity of particle collision and avoiding obtaining motion information with difficulty. Experimental prototype of banana vibrating screen under variable parameters was manufactured to verify the feasibility of simulations. Because the complex non-linear mathematical model is the basis of optimization. Based on the simulation data this paper applied the least squares support vector machines (LS-SVM) to establish relationships between vibrating parameters of banana screen and screening performance. LS-SVM based on statistical theory can effectively solve the mapping problem of small sample. At same time, in order to improving the quality of modeling, the kernel parameters of SVM were optimized by particle swarm optimization (PSO). Considering multi-extremum, large-scale, and non-differentiable of this computational model, the artificial fish-swarm algorithm (AFSA) with strong robustness and global convergence was applied to vibration parameters optimization. Finally, the optimal vibration parameters were: vibration amplitude 2.4mm, vibration frequency 21Hz, vibration direction angle 40 degrees.

Sieving is a technique for separating particles of different sizes. It is widely used in many granular media industries such as the construction, mineral separation, medicine and food fields [1-3]. When small particles penetrate the plate under suitable vibration source, other particles run to outlet indicating that the screening process finished. As an important screen machine in industrial screening, banana screens which named by the curved screening plate have better performance and throughput. The curved plate can make the same material layer thickness. With large inclined angle in the feeding end, it is helpful for small particles rapid movement and layering to penetrate sieve mesh. Then with the small particles and the inclined angles gradually decreasing, the time of screening process gets longer, and the thickness of material keeps stable. That makes the lager particles have more opportunities to pass though screening aperture. The research on the design and mechanism of banana screen has gradually attracted the attention of scholars [4-6].

Due to the complex collisions between particle-particle and particle-machine, plenty of time from traditional screen experiment including the statistics of particles motion information and size, DEM has been proved to be an effective method for dealing with granular systems. In 2002, Cleary simulated the separation process of 8000 3D-spherical particles in vibrating screen with inclined plate using DEM [7]. In 2007, Jiao and Zhao studied the penetrate motion of particle with 2D Sieve-DEM developed by VC++.NET [8]. Based on DEM considering the collision property and simulation condition, Liu and Tong analysed the relationships between parameter and screening efficiency [9]. Recent years, on the basis of DEM on screening simulation, the research of banana screen has become a hot spot. K. J. Dong do the deeply investigate in the effect of the equal inclination angle on the sieving performance of three-plate banana screen by DEM [4] in 2009. In 2013, J.W. Fernandez used SPH-DEM to simulate the movement of moist particles over the plate of banana screen [10]. Liu presented the mathematical study of particle flow on a banana screen deck using DEM [11]. In 2017, Li studied the sieving process of banana screen with the inclinations improved by Fibonacci sequence based on DEM [11]. But due to the lack of the mapping between vibration parameters and screening performance, it is hard to optimize reasonable parameters without the valid mathematic model of banana screen.

Particle morphology is another important impact on the particle micromechanical behavior. Cleary [12] have carried out three-dimensional simulations about screening process of spherical particles and non-spherical particles. The results showed that screening rate of spherical particles is larger than that of non-spherical particles. Li explored a simple two-dimensional crop seed DEM model, and discussed their effects on screening efficiency, the physical mechanism of separation [3]. Spherical, conical, cylindrical particles respectively in different vibration parameters and structure parameters, transmission speed and screening rate were studied by Frederik and Elskamp [13]. In this paper, non-spherical particles which match sands sphericity and a banana vibrating screen with a curved sieving surface were established by using DEM modeling. In order to study the relationship between vibration parameters and screening performance, Brereton and Dymott based on particle penetrating probability theory of Gaudin established the mathematical model of two-layer thickness screening stage [14, 15]. Chen established a comprehensive screening model about vibration and structure parameters [16]. Li presented A novel application of non-linear regression modeling based on Support Vector Machines (SVMs) is used for mapping the sample space of operating parameters and vibrating screen configuration [17]. In this paper, Simulation data which can be verified by the adjustable parameters are used, and the optimization model of banana is established by using the optimized support vector machine. At last, the overall parameters of banana screen were optimized by intelligent optimization algorithm.

DEM is a means to study the mechanical behavior of granular media systems. A soft ball model considering the surface deformation of particles is used as the basis of contact theory. According to the calculation of the intergranular contact force between the normal and tangential displacement, calculation strength is small which is beneficial to engineering problem. Particles in the initial position (the inlet) with a certain initial velocity under the influence of gravity fell down screening surface. After that the collision occurred between particles.

Using the theory of contact mechanics and elastic mechanics to determine the force and the material displacement, the speeds and positions of all particles in banana screen are constantly updated along with time by applying Newtons second law [18,19]. When the particles movements of whole system stop, that is system balance, iteration process ends. All the particles in the working surface conform to Newton's second law. These equations are:

where mi is particle-I mass; ri is position vector; Fcn,ij and Fct,ij are respectively Normal and tangential contact forces which are caused by intergranular collisions; Fdn,ij and Fdt,ij are respectively normal and tangential damping; g is gravity; Ii is rotational inertia; Tij is the torque generated by rolling friction; Mij is contact torque. After the time step t, the new velocity and location of the granules are obtained:

DEM has been successfully used in non-spherical shaped particles interactions and has provided useful qualitative information of particles [20-22] (Cleary, 2009; Zhu et al., 2008; Elskamp et al., 2015). Gabriel et al. (2013) conducted a multi-sphere pellet model of iron ore to perform DEM simulations in both the slipping and the mill tumbling, and the results showed a good agreement with experiments [23]. In 2006 Cho, G. C. [24] mentioned that the sphericity of the crushed sand is generally 0.7-0.8, and the sphericity of natural sand is generally 0.5-0.9. The sphericity of the sand model selected in this paper is consistent with the sphericity of the sand.

As can be seen from the Fig. 2 and Fig. 3, the 3D-DEM modeling of banana screen was established to simulate the screening process of non-spherical particles using software-EDEM. Length, width and height of banana screen were arranged as 160 mm, 28 mm and 80 mm. The simplified banana screen model is composed of screen factory, the curved screening surface and screening box. Meanwhile the curved screening plate has 5 decks, and the angle difference of neighboring decks is 5.5 degrees. In addition, the inclination of the third deck was invariably 14degrees when banana surface was in a straight-line oscillation. Vibration parameters including frequency, amplitude and vibration direction angle were mainly set by single factor experiment. The detailed parameters and simulation conditions were listed in Table 1. In order to provide more data to complete the mathematical mapping, orthogonal tests were conducted. Each of the three predominant factors was segmented into four levels whose values were chosen based on the single factor experiment above, which were listed in Table 2. All screening efficiency data were calculated, the mathematical model was established to optimize the parameters and the optimal combination of vibration parameters under the highest screening efficiency in later chapters.

Assessment criteria of screening performance can not only effectively express the quality of screening performance, but also be the foundation of mathematical modeling. We choose as Unit-time Screening Efficiency to stand for screening capacity and screening efficiency:

where is the screening efficiency in unit interval, mS1 and mK1 are the mass of particles whose diameters smaller than the aperture size in the undersized material respectively, mS2 and mK2 are total mass of particles whose diameters smaller than the aperture size respectively. tis the duration of the sieving process.

To verify the reliability of the simulation, the characteristics of experimental prototype are simple structure, short period, easy installation and maintained. Above all many parameters of banana screen such as incline angle, vibrating direction angle and so on can be adjusted and the structure is widely used in bolt fixing type. The vibrating screen was presented in Fig. 4, and Fig.5 showed that the vibrating motor is installed on the mounting rack to provide exciting force. The purpose of adjusting vibration direction angle is achieved through fixing the shaft at one end of the mounting bracket and adjusting the mounting hole at the other end to the different positions. As shown in Fig. 5, the specific scope of the adjustable are: 15, 25, 35, 45, 55, 65, 75 and 85.

In this part, the paper carries out the comparison between physical experiment and simulation experiment. The result was listed in Fig. 7. In order to improve the reliability of contrast as far as possible, the material selected as sands with the shock type-based vibrating screen (Fig. 6) tried to meet size distribution of granules in the EDEM model. Meanwhile the main conditions of physical experiment are as follows: capacity 0.5 ton/h, vibrating amplitude 2.2 mm, vibrating frequency 22 Hz, the aperture 0.7 mm and the diameter of mesh 0.4mm. Under different vibrating direction angles, statistical regularity of Unit-time Screening Efficiency was conducted. But physics experiment and the simulation experiment cannot completely consistent. Because the process of numerical simulation cannot fully meet the conditions of physical experiments, such as the property of particle, the particle size distributions, the complex random particle shape and so on. Unit-time Screening Efficiency has a certain gap in physical experiment and simulation experiment. More important, the effect of vibration direction angle on Unit-time Screening Efficiency is consistent (same crest value and variation tendency). Fig. 7 showed that numerical simulation can reflect the law of screening, and screening mechanism research can be carried out by using DEM-numerical simulation method.

In this paper, the vibration parameters (vibration amplitude, vibration frequency, vibrating direction angle) are the mainly optimized parameters of vibrating screen. In industrial production, with the fixed equipment structure and craft parameters, the vibration parameters (that is operation parameters) are the most direct optimization parameters in production site. The purpose of building mathematical modeling is to optimize the parameters of banana screen. The optimized parameters are effective way to improve screening performance. High-dimension, non-linear and complex mathematical mapping between vibrating parameters and Unit-time screening efficiency was solved by support vector regression (SVR) which can deal with small sample problems and has good generalization ability using the principles of structural risk minimization. Kernel function directly affects the quality of SVR. In this paper, in order to improving the leaning ability and the predicting ability of the SVR modeling, the intelligent algorithm-particle swarm optimization was used to optimize the parameters including penalty parameter C and Kernel function parameter in Radial Basis Function-RBF [25].

Linear regression which is basis of explaining the nonlinear regression is an important part of SVR [25]. All training data sets xi,yii= 1, 2, 3, n, xiRn, yiR, under the fitting precision , are fit by the linear function as possible f(x)=wx+b. The corresponding function as follow:

At the same time, in order to control the complexity of functions, according to the optimization theory, this paper optimized w2 and minimized the VC dimension to control the expected risk of the whole sample.

Optimal parameters C, in RBF which depends on SVR generalization performance are further complicated due to SVM model complexity. As an intelligent algorithm in computing, PSO algorithm was inspired by the behavior of birds. Each group of particles (similar to birds in nature) in algorithm are the optimization goal of a set of potential solutions, and each group of particles have a N-dimensional search space on behalf of the number of parameters to be optimized in combinations [26]. The fitness of each group of particles can get the corresponding value. Within the search space, particle swarm with a certain flight direction and initial velocity varies with the individual and group flight experience for dynamic adjustment, so as to realize the globe optimization solution.

where x1 is vibrating amplitude, (mm), x2 is vibrating direction angle, (), x3 is vibrating frequency, (HZ)The function relation is difficult to express using a simple function because of its highly nonlinear. The data of DEM solutions were used as input and output sample data listed in Table 3 for training and testing. Of the 44 groups of data, 35 groups were chosen randomly as training data and the remaining 9 groups of data were selected as testing data. The data which were listed in Table 3 consisted of two parts: single factor experiments and orthogonal test. The total sample size meets the need of regression modeling. In this paper the lower limit and upper limit of SVR parameters (C, 2) in PSO optimal process were set in Table 4. At last the optimal results also listed in Table 4.

Fig. 8 shows PSO-SVR ability of learning about simulation data of 35 samples. From Fig.9, we can see that the 9 sets of testing data results obtained by DEM-solution and the predicting outcomes established by PSO-SVR are compared. The two do have errors, but the overall trend and output errors are within acceptable limits. At the same time, two graphs show that the model established by PSO-SVR has good learning ability of samples, and the generalization prediction ability of fresh data is also better. In conclusion, vibration parameters of the sieving banana screen can be optimized by using the model described above.

Computation model is a highly non-linear, multiple maximum and non-differentiable large computational problem. Although the traditional regression algorithms such as Powell method and gradient decent method have their merits, its hard to solve the PSO-SVR modeling which doesnt possess strict mathematical conditions for example differential and continuous. As an intelligence algorithm, Artificial Fish Swarm Algorithm (ASFA) has the advantages of global optimality, robustness and high convergent speed [27, 28]. The algorithm simulates fish foraging, tailgating and clustering behavior, and the local optimization of each fish can achieve global optimization, which has been used to solve various combinatorial optimization problems.

In the actual process of banana vibrating screen, vibration strength needs to keep within the reasonable limit avoiding particles to attach screen and to excessive fly. So, the feasible region range of each design variable is the constraint condition of parameter combination optimization. According to the mathematical model established above, the relationship between parameters and Unit-time Screening Efficiency needs to be optimized and optimization objectives can be expressed as:

Suppose the artificial fish (X=x1, x2, x3,, xn), individual fish xi stands for optimal variables such as vibrating frequency. In this algorithm, Distance Perception suggested scope of individual fish activities; individual fish moving step length value and the other main parameters was listed on Table 5. Fig. 10 presented the flowchart of AFSA-PSO-SVR for optimization.

The change of 20 iterations is shown in Fig. 11. By the whole algorithm of AFSA-PSO-SVR, the optimal combination is as follow: vibration amplitude 2.36018 mm, the optimization results of vibration frequency 20.61352 Hz, vibrating direction angle 40.339 screening efficiency 55.0654 %. The round numbers of combination parameters (amplitude of 2.4 mm, vibration frequency of 21 Hz, vibration direction Angle of 40) were used to simulate the sieving process of banana screen. DEM-solutions result is about Unit-time Screening Efficiency of 56.1 %. The non-parametric model established using the integration of DEM and SVR, combined with ASFA algorithm in subsequent parameter optimization offered insights to the design and manufacture of vibrating banana screens.

1.DEM-solutions which instead of a time-consuming physical experiment can effectively simulate the irregular particles movements considering the collisions and material properties in banana screen. The variation tendency of screening efficiency under the different vibration parameters between simulations and physical experiments is consistent.

2.Mathematical modeling of highly nonlinear screening process is performed using SVR that was optimized by PSO. The mapping which provides the basis for parameter combination demonstrates good learning and generalization ability.

3.Non-differentiable and highly non-linear SVR modeling of banana screen was optimized by AFSA. The optimal combination is as follow: vibration amplitude 2.36018 mm, the optimization results of vibration frequency 20.61 Hz, vibrating direction angle 40.339 screening efficiency 55.07 %.

The authors gratefully acknowledged the support from the Program for scientific and technological innovation flats of Fujian Province (2014H2002). Fujian Natural Science Foundation (2017J01675). Key projects of Fujian provincial youth natural fund (JZ160460). 51st scientific research fund program of Fujian University of Technology (GY-Z160139). No part of this paper has published or submitted elsewhere. The authors declared that they have no conflicts of interest to this work. All authors have seen the manuscript and approved to submit to your journal.

become a vibrating screen expert in 3 minutes | m&c

become a vibrating screen expert in 3 minutes | m&c

Vibrating screen is widely used in mining, building materials, transportation, energy, chemical etc. It is used for material classifying, washing, dewatering and screening. In this article, you will learn about the installation and debugging (test run)of the vibrating screen and the operation skills to improve the screening efficiency, which will help you to be an expert in the vibrating screens area.

The installation of each part shall be carried out in sequence in strict accordance with the drawings of support or hoisting, and the actual rigidity marked on the end face shall be matched before the installation of spring parts. The base of the shaker must be flat and stable.

Connect the screen box to the supporting or hanging device, and adjust it according to the specified Inclination after installation. For hanging screens, the inclination angle of screen box and the level of main shaft of screen box shall be adjusted at the same time.

During installation, the base of the motor shall be leveled, the motor level shall be corrected, the center line of the corresponding groove of the two belt wheels shall be overlapped, and the tension of the triangle belt shall be appropriate.

(1) Operator shall read the duty record and carry out the general inspection of the equipment before working. Check the tension of the triangle belt, the oil level in the vibrator, the tension of the screen surface, the fastening of the bolts and the damage of the screen surface.

(3) When the vibrating screen is running, it is necessary to check the working condition of the vibration exciter and the screen box. The temperature rise of the bearing should be checked after the vibrating screen is stopped.

In addition, reasonable and scientific installation, debugging and operation of the vibrating screen can effectively improve the classification efficiency, prolong vibrating screen service life and reduce the labor intensity of the operator.

optimised vibrating screens boost family business - quarry

optimised vibrating screens boost family business - quarry

A third-generation family quarrying business is maintaining its commitment to quality across changing seasons through its decades-long preference for sophisticated and optimised vibrating screens and their screen media.

The Peace River region of northeastern British Columbia, in Canada, is often associated with rich soils and moderate temperatures, making it an ideal agricultural environment. But there is also plenty of income to be made just below the surface. An aggregates producer recognised this in the mid-1960s and decided to take action.

In 1966, Nels Ostero established a sand and gravel operation in the Peace River Region Nels Ostero Ltd. Since then, the company has grown significantly but has always remained humble and family-orientated. Nels Osteros son Tom Ostero took over the plant in 1982, and in 2007, his grandson Nilson Ostero assumed the manager position where he remains today.

The plant, which resides on 130 hectares of land, supplies sand and gravel for residential and commercial needs in the Peace River regional district. The companys products are used in concrete applications, asphalt plants, oil fields and highways. With a capacity of more than one million tonnes per year, the equipment on-site plays a huge role in the plants success.

To keep up with the demand of sand and gravel products, the quarry requires top level machinery. There are 11 vibrating screens, two crushers and dozens of loaders, trucks and excavators on-site, all of which need to be performing efficiently.

Haver & Boecker Niagara has been delivering dependable equipment to Nels Ostero for decades. In fact, the Canadian-based screen manufacturer has been Nels Osteros go-to since the quarrys first years of establishment, back when the manufacturer was known asWSTyler.

The first piece of Haver & Boecker Niagara equipment the company purchased was a Ty-Rock (today known as an F-class vibrating screen) installed in 1966. Since then, they have added a number of technologies from themanufacturer.

My father chose the company because of the reliability of the equipment, Nilson Ostero said. I have tried some different equipment and screen media brands over the years, but nothing compares to Haver & Boecker Niagara.

Most recently, Nilson Ostero replaced his two 4.8m x 2.1m machines, which were situated at the finishing end of the operation. They were supplied by another manufacturer and had been running since the 1980s. The equipment was outdated, inefficient and required more maintenance than the value they offered. He turned to Haver & Boecker Niagara which evaluated his operation and recommended implementing two Niagara T-class machines. The new screens have proven themselves a good fit, increasing capacity and requiring little to no maintenance.

The T-class machines are on their third season with us, and we havent had a single issue, Nilson Ostero said. They allow us 20 per cent more capacity than our old screens, but more importantly they are stronger andmore reliable.

Haver & Boecker Niagara characterises the T-class machines as highly efficient and durable, which is important to the success of any screening business. This is especially true for this particular operation, which runs year-round and sees the effects of cold weather on material and screening equipment.

The British Columbia winter weather averages about four degrees Celsius but can dip down as low as -40oC. While some screen plants shut down their whole operation in the winter, Nilson Osteros high performing equipment allows him to performcrushing and screening year-round. When temperatures remain steadily below -3o C, they pause aggregate washing. However, even with a portion of the operations process shut down, they are still able to produce more than an operation that has to completely shut down for several months.

The colder it gets outside, the stickier the material becomes, Nilson Ostero said. The extra moisture can lead to blinding and pegging, resulting in downtime for maintenance to clear out the material. That doesnt happen with the T-class machines.

At the end of the day, if the guys are working with good equipment, they are happier and perform better, Nilson Ostero said. Safety is obviously a big deal, but another thing is providing efficient, top-notch machines that dont require unnecessary maintenance.

Maintenance is required on all jobsites, but unexpected maintenance and subsequent shutdowns can equate to a significant loss of money for any company. Scheduled maintenance activities are only possible with thorough analysis and planning as well as quality equipment and screen media. Nilson Ostero consistently found that any attempt to cut corners only resulted in lost profits. Each time he experimented with lower-cost screen media, he would watch as unexpected downtime and lost revenue skyrocketed.

Until the operation implemented the Haver & Boecker PROdeck method, the standard screen media required attention after every eight shifts, and a complete change-out every two weeks. PROdeck evaluates the screening process to effectively blend screen media for the highest production with the least amount of unscheduled downtime. Markus Kopper, general manager of Haver & Boecker Niagara Rocky Mountains, and Dave Warden, Haver & Boecker Niagara sales manager, worked with the company to determine the optimal screen media combination for the operation. This included a combination of Ty-Max, Ty-Wire and traditional woven wire, as well as Majors Flex-Mat.

Haver & Boecker Niagara partners with each customer and thoroughly evaluates an operation before making recommendations, Kopper said. For Nels Ostero, they were able to achieve a 70 per deck increase in wear life with our PROdeck approach.

Nilson Ostero also consulted with Haver & Boecker Niagara to determine if any additional upgrades for his vibrating screens could reduce the time required for maintenance and screen change-outs. Hefound a time saver in the companys Ty-Rail quick-tensioning system. The new T-class machines are equipped with this system, which combines the tension rail and all hardware together in one assembly. Ty-Rail has simplified the process and saves his team at least three hours each time a change-out is needed, as well as helping to eliminate losing nuts and bolts into the hoppers below.

A complete screen change-out, on one screen, would have normally taken us five or six hours, Ostero said. But with Ty-Rail, we can do it in as few as three hours. And guys arent dropping bolts every 15 seconds, so thats anadded bonus.

The three-hour time savings, coupled with increased throughput, resulted in an overall production increase over the first year. On top of that, it saved an estimated eight to 10 days of downtime per season, which equates to an increase of thousands of dollars.

However, Ty-Rail wasnt the only time-saving option Nilson Ostero discovered. After years of frequently replacing worn out cross-beams, he opted to add Zip-Guard to his T-class machines. The 13mm-thick polyurethane liner is designed to reduce the impact of passing material by protecting the cross beams from wear. This results in increased equipment longevity and minimised downtime formaintenance.

All of the technologies on-site are supported by an ongoing service program, which gives Nels Ostero an added level of confidence in the products. Haver & Boecker Niagara begins every service visit with its signature Pulse vibration analysis. The advanced vibration analysis technology is designed to help customers, like Nilson Ostero, examine the health of their vibrating screen. Haver & Boecker Niagara technicians use the technology and analysis to help detect irregularities that could translate into diminished performance, decreased efficiency, increased operating costs and imminent breakdowns.

Markus and his team used Pulse to help me spot issues that our team wouldnt have normally been able to find, Nilson Ostero said. Haver & Boecker Niagara first ran it on my machines right after they installed them, and now they run it once a year. It has caught problems that may have cost me money down the road, including a twisted frame on one of my screens. We knew there was a problem with the unit, but with Pulse, Haver & Boecker Niagarasservice technician determined exactlywhat was wrong.

Since the companys inception, Nels Ostero has grown to become one of the largest sand and gravel producers in the area employing more than 30 people, several of whom have been with the company for more than 15 years. With a constant focus on relationships and quality, the Ostero family built a longstanding business on enduring whatever the economy throws at them, all while maintaining their reputation for consistently providing quality product that meets the demands of theircustomers.

Looking toward the future, Nilson Ostero hopes to continue to grow the business by increasing output year over year, continue retaining and adding employees, and perhaps most importantly keep the businessin the family and one day pass it on to his children tocontinue the family tradition.

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