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Vibrating Screen Efficiency Calculation STEP by STEP – VSMA Method

Maximize Your Screening Performance – Learn to Calculate Vibrating Screen Efficiency Step by Step.

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Section summary
1. Introduction
2. Vibrating screen efficiency calculation methodology STEP by STEP
3. Industrial efficiencies

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This page provides a detailed methodology for calculating the efficiency of vibrating screens, essential for in mining, quarrying, and mineral processing operations.

1. Introduction

Vibrating screen efficiency, as defined by the Vibrating Screen Manufacturers Association (VSMA), is a critical parameter that measures the effectiveness of a screening process in separating materials of different sizes. It is expressed as the percentage of undersize material in the feed that successfully passes through the screen apertures. Calculating screening efficiency is essential for process engineers to evaluate the performance of their screening operations and identify areas for improvement. Factors such as the nature of the feed material, screen design, operating conditions, and maintenance practices significantly influence efficiency.

The VSMA provides standardized methods and formulas to calculate screening efficiency, enabling engineers to make data-driven decisions and ensure their screening processes meet the desired performance standards.

2. Vibrating screen efficiency calculation methodology STEP by STEP

How to calculate the efficiency of a vibrating screen ?

The efficiency of a vibrating screen can be calculated thanks to the following formula :

Efficiency =

(% of undersize in feed which actually passes through the screen)

/

(% of undersize in the feed)

Step 1 : Define the characteristics of your feed

It is important to analyse 1st the characteristics of the feed, especially :

- The size distribution and especially the % of the feed that is larger than the aperture you consider, the % of the feed that is smaller than the aperture of the screen you consider (this value is used in the denominator of the formula above)

Step 2 : Perform a trial

It is necessary to evaluate the actual % of undersized solids that will go through the sieve, this data is used as the numerator of the formula above. It is not possible to calculate it a priori so it is necessary to perform a trial.

Step 3 : Calculate the efficiency with the equation above

For example :

-The % of undersized vs the screen aperture in the feed, that then should go through the screen, is 55%.

- A test is ran and it is found out that 45% of the feed actually goes through the screen.

The efficiency is thus 45/55 = 81.8%

3. Industrial efficiencies

When calculating the required screen size for a specific application, the VSMA formula assumes an efficiency of 95%. It is pretty high and not always possible industrially. Note that achieving an efficiency of 100% is actually not possible in practice.

90% is usually considered acceptable, but in practice some vibrating screens are more in the 80-90% bracket.

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Sources

VSMA