Vibrating Screen Efficiency Calculations and Improvement
Jan. 07, 2022
Vibrating Screen Efficiency Calculations
For the efficient use of Vibrating Screens, several conditions need to be met, starting from selecting a suitable screen. Many factors related to the screened material, such as type, humidity, and size distribution, should be considered in selecting the right screen. Choosing the correct screen type and the right dimension requires expertise. FengWang's expert engineers will boost your profitability by choosing the right screen for you.
Another critical factor affecting screening efficiency is the choice of the screen baffle, which can be made of materials such as wire and polyurethane. The screen baffle should be resistant to vibration, have sufficient open space, and be resistant to wear.
The efficient operation is related closely to how the screen is fed. The belt that feeds the screen should provide feeding in parallel with the flow direction of the material and in a manner that brings the materials to the center of the loading vessel.
Another critical factor in efficient screening is the layer height (or bed). The layer height refers to the height formed by the layer on the wire surface at the point where the material is loaded. The ideal height is four times the screen aperture.
The capacity and efficiency of Vibrating Screens are usually inversely proportional. The usual target is a screening efficiency of 95%. An efficiency of 99% will equate to a significant loss of capacity.
Screening efficiency is the ratio of undersize material in the feed that passes from the screening media to the undersize material that should pass from the screening media. This ratio is desired to be 100%. However, this is not possible due to the factors affecting the screening process.
However, Vibrating Screens producers and quarry managers have determined acceptable efficiency ranges to ensure an optimum screening process. Screen efficiency should be 90%-95% concerning the above formula according to the determined ranges.
Feed rate is the main parameter dictating efficiency.
If the flow rate is below the screening capacity of the media, the screen runs idle, so no screening is carried out. On the other hand, if the flow rate is above the screening capacity of the media, the screen runs under the overflow rate, and in this case, no screening is made due to the high material depth on the media. Accordingly, screen selection must be made with due attention paid to the flow rate to obtain maximum screening efficiency.
Screening efficiency is affected by the factors listed below:
Wear, abrasion, and tearing in the screen baffle.
Feeding too much or too little material onto the screen.
Large grade changes.
A humidity level of the screened material.
The efficiency of the machine used before the screening.
How to Improve Vibrating Screen Efficiency?
Screening of vibrating Vibrating Screens is the crucial link of mines, chemical plants, and cement plants. Screening performance refers to the high-quality ratio of the authentic screening product to the material included in the feed that is less than the sieve opening. Screening performance directly influences production effectiveness.
The aspects that affect the screening performance of vibrating Vibrating Screens as well as the approaches to enhance the screening performance are as below:
1. Properties of materials
( 1) The even more easy-to-screen fragments are included, the less complicated the material is to screen, as well as vice versa, the more difficult the material is to screen.
Particles with bit size d= 1-1.5 an (a is the size of the screen mesh) are easily embedded in the screen hole of the vibrating Vibrating Screens, which is called obstacle fragments, affecting the material to travel through the screen hole. As a result, the more complex and obstructive particles the material has, the reduced screening performance.
( 2) Particles with round form are easy to go through square and circular holes of vibrating Vibrating Screens. At the same time, strip, sheet, and polygonal materials are challenging to pass through the square and circular hole shaker Vibrating Screens but very easy to go through rectangle-shaped hole shaker Vibrating Screens.
( 3) Water content. In dry screening, materials with high wetness content and far better wettability and bond are more accessible to agglomerate as well as block the screen holes and greatly minimize the screening efficiency.
( 4) Bulk thickness. When the bulk thickness of materials is large, the screening performance of the vibrating screen is symmetrical to the bulk thickness.
2. Residence of Screen Plates
( 1) Opening rate. The ratio of the screen opening location to the screen panel area is called the opening price. High opening prices produce high screening efficiency and production capacity; however, they cause short life of screen panels.
( 2) Screen hole shape. The screen opening shape differs, and the material's passing capacity varies considerably. When picking the hole sort of the vibrating screen, it ought to be appropriate for the bit shape o
f the material.
( 3) Size of screen plates. The proportion of size to the screen plates needs to be within a suitable array, typically 2.5-3.
( 4) Screen inclination. Reduced inclination angle, reduced manufacturing capacity; also large inclination angle, reduced screening efficiency. The inclination angle of the shaker screen is generally 0 ° -25 °, which of a fixed shaker screen is 40 ° -45 °.
10 Methods to Improve Screening Efficiency
1. Attire Feeding
Constant and consistent feeding to ensure that the material is uniformly distributed on the screen to guarantee a greater production capacity and screening performance.
2. Feeding Volume
It should be effectively and reasonably fed to stay clear of too much or inadequate.
3. Boosting Opening Rate
Boosting the opening price of the vibrating screen plate and the high opening rate is helpful to improve the screening result. Typically, the opening price of a stainless-steel screen plate is higher.
4. Change Feeding Mode
In some cases, the feed of the vibrating screen is not fed along with the full-screen size, leading to insufficient utilization of the screen plate.
5. Reduce Plugging Rate
The self-cleaning screen plate can be selected to reduce the blocking price of the vibrating screen plates.
6. Adjusting Inclination
Modification of the inclination angle of the vibrating screen machine can be thought about. An appropriate inclination angle is conducive to decreasing the material density.
7. Wet Screening
Wet screening can be used to boost the screening result.
8. Adjusting Balance Weight
For a circular vibrating screen, readjusting the weight can be considered to improve the screening performance.
9. Regulating Feed Moisture
For dry screening, feed moisture needs to be strictly managed.
10. Including Fixed Screen
If the authorization, the fixed screen is included in the feeding end of the vibrating screen.