Vibrating screen theory and selection principle

Vibrating screen is a very important stone grading and screening equipment in the mining industry.It can greatly increase the utilization rate of stone and reduce the failure rate of mechanical equipment in the subsequent processes.It is different from traditional manual screens.To help everyone For a good understanding of this equipment,Hiside has compiled the principles and selection techniques of vibrating screens for your reference.

Vibrating screen theory

The working process of the vibrating screen will use the reciprocating vibration generated by the oscillating excitation,and the upper rotary hammer of the vibrator will cause the surface of the vibrating screen to form plane vibration.The lower rotating weight makes the screen surface produce cone-shaped rotary vibration,and its combined effect makes the screen surface produce double-rotation vibration;

The process of dividing the scattered materials with different particle sizes through a single or multi-layer sieve surface with evenly distributed holes multiple times into several different levels is called sieving.The particles larger than the sieve hole remain on the screen surface,and the particles smaller than the sieve hole pass through the sieve hole,and finally the coarse and fine particles are separated and the screening process is completed.

Vibration screening factor

The characteristics of the material to be screened(the content of the material under the sieve,the content of the difficult-to-sieving particle,the content of moisture and clay in the material,the shape of the material,the specific gravity of the material,etc.);

The structure of the screening machine(screen area,number of screen layers,screen hole size and shape,screen hole area ratio,screening machine movement mode,amplitude and frequency,etc.);

The requirements of the beneficiation process(processing capacity,screening efficiency,screening method,screening machine inclination),etc.

Selection principle of vibrating screen

(1)After determining the screening area,the width of the screen surface should be at least 2.5 to 3 times the size of the largest piece of material to prevent the screen from being blocked by large pieces of material.

(2)In order for the sieve to be in good working conditions,the ratio of the length to the width of the sieve should be selected within the range of 2 to 3.

(3)A reasonable screen surface material and structure should be selected to adapt to the working conditions.

(4)Determination of the sieve hole size.For fine sieves and curved sieves,when linear vibrating sieves are used for fine particle screening,the sieve slit size is 2 to 2.2 times the separation particle size,and the maximum is not more than 3 times;for vibrating sieves,For the screening of medium-grained materials,the mesh size is 1.2 times the separation particle size;when used for coarse-grained materials,the mesh size is 1.05 of the separation particle size;for probability screens,the mesh size is generally the actual separation 2 to 2.5 times the particle size.

(5)Determine whether to use double-layer or multi-layer sieves.When the size range of the material to be screened is wide,when the double-layer screen is used as a single-layer screen,the processing capacity of the screening machine can be improved,and the lower screen can be protected,and the life of the lower screen can be prolonged.The selection of the sieve hole size of the upper sieve of the double-layer sieve should generally be determined according to the characteristics of the feed particle size,and the amount of the material under the upper sieve,which is equivalent to 55-65%of the original feed amount,can be considered as the sieve hole.size.

Note that when the content of the under-sieve particle in the raw material exceeds 50%,there are many difficult-to-sieve particles,the material contains more viscous mud and high water content,you should try to avoid using a double-layer sieve as a single-layer sieve.

(6)Determine the effective working area of the sieve.The sieving area calculated according to the production process requirements is the effective area of the sieve,and the size of the sieve is the nominal area of the sieve.For the vibrating screen used for the screening of medium-sized materials,the effective sieving area should be 0.8～0.85 of the nominal area of the sieve Times.Of course,this is closely related to the opening rate of the sieve on the screen.

(7)Heavy-duty vibrating screens are mostly used for materials above 200mm;circular motion screens are mostly used for materials above 10mm;linear vibrating screens and high-frequency vibrating screens are mostly used for desilting,dewatering and grading.

(8)When conditions permit,the seat screen should be selected first to facilitate inspection and maintenance.When a hanging screen must be selected,the lifting height should be minimized to reduce the swing range of the vibrating screen and facilitate production operations.

The above is the principle and selection principle of the vibrating screen that Hiside has compiled for you.I hope it can be helpful to everyone.