Vibrating screen is a kind of machine with high screening efficiency, which is widely used in the classification of ore, coal and other materials.

However, because the screening efficiency of vibrating screen is related to such factors as particle size characteristics of materials, material humidity, screen hole shape, screen surface inclination, screen surface length, screen surface movement characteristics and material thickness on the screen, theoretical analysis is very difficult.

The screening efficiency of circular vibrating screen and related problems are analyzed. The calculation of screening efficiency is theoretically analyzed, but it is still difficult to apply it to practical calculation and design. The relationship between screening efficiency and feed water content, mesh shape, screen surface parameters and other factors was qualitatively analyzed.

In the design of vibrating screen, the general qualitative consideration for determining the screen surface length is that the screen surface length is proportional to the screening efficiency. That is, when the screening efficiency is required to be high, the screen surface length should be taken as a larger value. It is suggested that the length width ratio of the mining classifier should be about 2;

The length width ratio of coal vibrating screen used for final classification, dehydration and disintermediation is about 1.5-2.5. The method of determining the screen surface length of vibrating screen under the condition of considering screening efficiency is put forward, which makes the determination of screen machine length more reasonable

**The percentage by weight of the fine fraction of inch. Therefore, the screening efficiency can be calculated by the following formula:**

**β (a_ θ)**

**E=——–x100% (2-1)**

**a( β- θ) In the formula, a – content of particles smaller than the mesh size in the raw feed (%);**

**β—— The content of particles smaller than the mesh size in the undersize product is%;**

**θ——- Sieve The content of particles smaller than the mesh size in the upper product is%.**

**In Formula (2-1), if it is considered that the size fraction of the product under the sieve is smaller than the size of the sieve opening β= 100%, then Formula (2 – 1) can be simplified as: 100 (a- θ)**

**E=———x 100%**

**a(100- θ)**

**Therefore, when determining the screening efficiency according to Formula (2-2), only the following are required: (1) Take the average sample of ore feed, screen and analyze it, and get the data a; (2) Take the average sample of the product on the sieve to obtain the data θ , Then a, θ The sieving efficiency of the corresponding particle size fraction can be obtained by substituting the data into Formula (2-2).**