Screening is an important part of the sand and gravel aggregate production line. The purpose of screening is mainly to separate materials with different properties. When crushing and processing sandstone, ore and other raw materials, screening is required to ensure that the sandstone material meets the crushing requirements of the crushing plant.
Most screening machines use rotation, vibration, reciprocating motion, shaking and other actions to screen the materials according to the particle size of the materials, or remove moisture, impurities, etc., and then crusher again to process and improve product quality.
According to its structure and motion characteristics, the screening machine is divided into circular vibrating screen, linear vibrating screen, resonance screen, fixed screen, roller screen, thick screen, cylindrical screen, etc. Different sieves have their own materials when it comes to processing materials. Benefits and scope of application. The most common types in mine production are circular vibrating screens and linear vibrating screens. This article introduces the 7 differences between linear screens and circular vibrating screens.
The circular vibrating screen is a centrifugal force generated by the rotation of the eccentric block in the vibrator, which makes the screen box, vibrator, etc. forced into continuous circular motion or approximate circular motion. The material and the screen box are continuously thrown on the inclined screen surface; Layering when throwing. Sift the pellets as they fall.
The circular vibrating screen has the characteristics of reliable structure, high screening efficiency, strong excitation force, durability, easy maintenance and safe use. It is widely used in mining, building materials, transportation, energy, chemical and other industries.
Linear vibrating screens are widely used in the mining industry. It uses a vibrating motor to excite the material, so that the material is thrown onto the screen and travels in a straight line. The material enters the feed port of the screen in multiple layers from the feeder in multiple layers. The screens produce several sizes of oversized and undersized and are discharged separately from their respective outlets.
The linear vibrating screen has compact structure, reasonable vibration parameters, stable movement, low energy consumption, high output, high screening and dehydration efficiency, fully enclosed structure, no dust overflow, automatic discharge, and is more suitable for assembly line operation.
The material on the linear screen moves forward in a straight line, and the material on the circular vibrating screen moves in a circular motion.
The linear vibrating screen exciter is composed of two shafts, which works on the principle of vibration motor excitation, so it is also called a double-shaft vibrating screen.
Because the exciter is a shaft, the circular vibrating screen uses an inertial motor to work, so it is also called a single-shaft vibrating screen.
The material of the linear vibrating screen moves smoothly on the screen surface, such as uneven feeding or the humidity of the material is viscous, and it is easy to plug the hole.
The material of the circular vibrating screen moves in a parabolic circular trajectory on the screen surface, so that the material is dispersed as much as possible, thereby improving the bounce force of the material, and the material stuck in the sieve hole can also jump out, reducing the phenomenon of hole blocking.
Generally speaking, the inclination angle of the screen surface in the production of linear vibrating screen is small, and the height of the screen is reduced, which is convenient for process layout.
The circular vibrating screen usually has an installation inclination angle of 15-20 degrees, which changes the movement speed of the material along the screen surface and improves the screening efficiency.
The production materials of linear vibrating screen are mainly light plates or stainless steel plates.
The material of the circular vibrating screen is thicker, and the box body is made of manganese steel, which can resist the impact of the material in the screening process.
The linear vibrating screen can adopt a fully enclosed structure, without dust overflow, which is more conducive to protecting the environment.
The exciter of the circular vibrating screen is arranged above the center of gravity of the screen box, which is conducive to the rapid dispersion of the material, and the processing capacity per unit time is higher than that of the linear vibrating screen.
Linear sieves mainly screen fine granules, light specific gravity, low hardness materials, mainly dry powder, fine granular or micro powder materials, usually in the food, chemical, building materials, pharmaceutical industry is widely used.
The circular vibrating screen mainly screens materials with large proportion, large particles and high hardness, and is widely used in mining, coal, quarrying and other mining industries. In addition, some difficult-to-screen materials can also be used circular vibrating screen.
The resonant screen is a kind of vibrating screen with the vibration frequency of the screen surface consistent with the natural vibration frequency of the screen surface (including the loaded materials), which can effectively use the natural frequency of the equipment and work in a state close to the common vibration, so it consumes very little power. However, the structure of the resonance screen is more complex, the adjustment is troublesome, the failure rate is high, and there are many problems in terms of structural strength.
The working part of the fixed screen is fixed, and the screening of the material depends on the material sliding along the working face under the action of its own weight. Fixed grid screens are widely used in concentrators, mainly for pre-screening before coarse or secondary crushing. The fixed screen has a simple structure, easy to manufacture, can directly unload the ore onto the screen surface without consuming power, and saves costs. However, its productivity is low and the screening efficiency is low.
The working surface of the roller screen is composed of a transversely arranged rolling shaft with a plate on which the fine-grained material passes through the rollers or the gap between the plates. The bulk material is driven by a roller to move to one end and discharged from the end.
The screen shaft of the roller screen is arranged according to different working angles, and the speed is faster when the material runs at a higher working angle; When the material is running at a lower working angle, the speed is slower. The materials under two different speed operation start to do axial movement when they meet at a certain position on the screen surface, so that the materials are evenly distributed on the screen surface and achieve the purpose of improving the screening efficiency. Roller screens are rarely used in concentrators.
The equal-thickness sieve is also called a banana sieve because it is shaped like a banana. The principle is an efficient screening technology developed based on the theory of the movement of the material group on the screen surface. The characteristic is that regardless of the percentage of particles smaller than the screen hole in the infeed, the thickness of the material layer on the screen surface remains unchanged or increases during the screening process: while the thickness of the material layer on the screen surface decreases during the screening process of the ordinary screening method. Therefore, the equal thickness screening method can increase the processing capacity of the sieve exponentially.
The working part of the cylindrical screen is cylindrical, and the whole sieve rotates around the axis of the cylinder, and the axis is generally installed with a small inclination. The material is fed from one end of the cylinder, the fine material passes through the sieve hole on the cylindrical working surface, and the coarse-grained material is discharged from the other end of the cylinder. The speed of the cylindrical screen is very low, the work is stable, and the power balance is good. However, its sieve hole is easy to block, the screening efficiency is low, the working area is small, and the productivity is low.