In the mineral processing area, the crushing, sand making, beneficiation operations, the screening process is often used and even indispensable.
But there are many kinds of screen machines with their own advantages and specifications, so what’s the difference between those commonly used vibrating screens and asked how to choose. In this article, we’ll detail the advantages and disadvantages of 8 kinds of screening machines, and tell you how to choose the right screening machine for your processing operation.
This article explains the characteristics of 8 kinds of commonly used screening machines and the screening equipment suitable for different processing stages in the sand and gravel production line.
Commonly used screening equipment mainly include vibrating screen, fixed screen, roller screen and so on.
1. Fixed screen
The fixed screen is a screening machine with a fixed screen surface. It is placed obliquely and the material is tilted at the high end. Without any external force, the ore is passed through the sieve by its own weight and divided into under-screen material smaller than the sieve hole and over-screen material larger than the sieve hole. Two levels of granularity.
The screening efficiency of the fixed screen is low, it is easy to block when the viscous water content is high, and the labor intensity is high during operation. However, because of its simple structure, easy manufacture, no power, and low cost, it is widely used in crushing operations. It can be divided into two types: grid sieve and strip sieve (bar sieve):
Grid screen : mostly used in the upper part of the raw ore receiving bin and coarse crushing bin, mainly used to control the particle size of the ore;
Strip screen: mostly used for pre-screening before coarse crushing and medium crushing.
2. Roller screen
The screen surface of the roller screen is composed of many parallel rollers with sieve discs staggered on them. The gap between adjacent rollers and discs is the sieve hole of this kind of sieve. The roller is driven by a sprocket or gear to rotate, and its rotation direction is the same as the material flow direction.
Roller screens are often used for screening of coarse-grained materials. They are suitable for screening soft and medium-hard materials. Its advantage is that it does not block the screen. The disadvantage is that the equipment is bulky, the screening efficiency is low, and the roller wears quickly.
3. Vibrating screen
Commonly used mine vibrating screens are not a certain kind of screening equipment, but a kind, usually inertial vibrating screen, self-centering vibrating screen, eccentric vibrating screen, heavy vibrating screen, circular vibrating screen, linear vibrating screen, etc. Below we focus on comparing the characteristics of these types of vibrating screens.
Inertial vibrating screen
The vibrator is installed on the screen box. As the screen box vibrates up and down, the instability of the amount of ore will affect the screening efficiency, and the processing capacity is small, which is suitable for medium and fine grades.
Self-centering vibrating screen (single shaft vibrating screen)
When the self-centering vibrating screen is working, the screen vibrates at high speed, but the spatial position of the grooved pulley remains unchanged, so it is called a self-centering vibrating screen. It has the same working principle as the pure inertial vibrating screen, but the belt wheel is concentric with the drive shaft in the structure, the center of the belt wheel remains stationary during the working process, and the motor runs smoothly.
The advantages are simple structure, easy manufacture, strong screen surface vibration, and high screening efficiency; the disadvantages are large vibration to the building and small processing capacity. Applies to the subdivision level.
Eccentric vibrating screen
The eccentric vibrating screen relies on the high-speed rotation of the eccentric drive shaft to make the screen vibrate, so it is called the eccentric vibrating screen. The eccentric shaft directly drives the screen frame to make a trajectory movement in the vertical plane with an amplitude equivalent to twice the eccentricity. The sieve size can reach 100~250mm. It is often used in the pre-screening process or the first screening process of sand and gravel materials. It is rarely used now, and inertial vibrating screens are mostly used.
The advantage is that the structure is sturdy, the amplitude remains the same when the feed rate changes, the vibration strength is large and constant, and it is not suitable to block the screen holes; the disadvantage is that the bearing structure is complicated and the inertia is large, and the building is easily vibrated due to incomplete balance during operation.
Heavy vibrating screen
It is suitable for sieving large lumps and dense ore. The screening efficiency is higher than that of a fixed screen, but the equipment investment is high, and it is suitable for large block classification.
Circular vibrating screen
The vibrating screen with a circular track, the screen surface is arranged obliquely, the material stuck in the screen hole can jump out, the screen surface is not easy to be blocked, and it is suitable for large blocks and medium subdivision levels.
Linear vibrating screen
The screen surface is installed horizontally, the movement track is straight, the screen surface is large, the amplitude is strong, the screening efficiency is high, and the processing capacity is large; but the structure is complicated, the price is expensive, the energy is high, and the amplitude adjustment is difficult. It is suitable for the screening of coarse, medium and fine aggregates, and can also be used as dehydration and desliming equipment in wet production.
Among the 8 types of vibrating screens, circular vibrating screens and linear vibrating screens are more common. Regarding the difference between the two, I have been unable to distinguish between circular vibrating screens and linear vibrating screens? These 9 major differences make you suddenly understand! “I have compared the article, you can click on the article to view it, and I will not go into details here.
With so many screening equipments, how to choose different stages of the sand and gravel production line? Generally speaking:
First stage screening: fixed screen (low screening efficiency, low equipment investment), heavy-duty vibrating screen (high screening efficiency, high equipment investment), roller screen (medium screening efficiency, high equipment investment);
Second stage screening: circular vibrating screen (high screening efficiency, low equipment investment), linear vibrating screen (medium screening efficiency, low equipment investment);
Third stage screening: circular vibrating screen (high screening efficiency, low equipment investment), linear vibrating screen (medium screening efficiency, low equipment investment);
Inspection and screening: circular vibrating screen (high screening efficiency, low equipment investment), linear vibrating screen (medium screening efficiency, low equipment investment).
It can be seen that in addition to the first stage screening, the second stage screening, the third stage screening, and the inspection screening adopt a circular vibrating screen or linear vibrating screen, but because the former has higher screening efficiency, circular vibrating screen can be selected.