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Jul. 17, 2020
Vibrating screens are currently the most widely used screening machinery in many industrial sectors. In the production process of screening, dehydration, desilting, and demediation of coal preparation plants, vibrating screens are basically working.
The vibrating screen is vibrated by centrifugal force generated by the unbalanced rotor (eccentric block and eccentric shaft) to vibrate at a certain frequency and amplitude. Therefore, the vibrating screen is mainly composed of an exciter, a screen box and an elastic support.
The screen box of the vibrating screen is similar to the shaking screen, and its amplitude can be changed by the amount of feed and other dynamic factors. The movement characteristics of the vibrating screen are high frequency and small amplitude, and the material makes a jumping movement on the screen surface, so the productivity and screening efficiency are higher. Vibrating screen is suitable for various screening operations in the mine.
According to whether the vibration frequency is close to or far away from the resonance frequency, the vibration screen is divided into a resonance screen and an inertial vibration screen.
The resonance sieve was once on the rise, and has been widely valued by various countries and developed rapidly; but in production practice, it has exposed the shortcomings of complicated structure, difficult adjustment, and many failures. In the screening operation, an inertial vibrating screen is widely used, which is generally called a vibrating screen.
Vibrating screen manufacturer is divided into the following categories according to the structure and working principle of the screening machine.
(1) Fixed screen
The working part is fixed, and the material is screened by sliding the material along the working surface. Fixed grid sieves are one of the more widely used in mineral processing plants, and are generally used for pre-screening before coarse crushing or medium crushing. It has a simple structure and is easy to manufacture. Without power consumption, the ore can be directly discharged onto the screen surface. The main disadvantages are low productivity and low screening efficiency, generally only 50-60%.
(2) Roller screen
The working surface is composed of horizontally arranged rolling shafts, with a plate on the shaft, and fine-grained materials pass through the gap between the rollers or the plates. The bulk material is driven by the roller to move to one end and is discharged from the end. Concentrators rarely use this kind of sieve.
(3) Cylindrical screen
The working part is cylindrical, and the entire sieve rotates around the axis of the cylinder. The axis is generally installed at a small inclination. Materials are fed from one end of the cylinder, fine-grade materials pass through the screen holes of the cylindrical working surface, and coarse-grained materials are discharged from the other end of the cylinder. The rotating speed of the cylindrical screen is very low, the work is stable, and the power balance is good. However, its sieve holes are easily clogged, the screening efficiency is low, the working area is small, and the productivity is low. Concentrators rarely use it as screening equipment.
(4) Plane sports sieve
The body is oscillating or vibrating in a plane. According to its plane motion trajectory, it is divided into linear motion, circular motion, elliptical motion and complex motion. Shakers and shakers belong to this category.
The shaking screen uses the crank connecting rod mechanism as the transmission component. The motor drives the eccentric shaft to rotate through the belt and the pulley, and the body is reciprocated in a certain direction by the connecting rod. The movement direction of the machine body is perpendicular to the center line of the support rod or suspension rod. Due to the swinging movement of the machine body, the material on the screen surface moves to the discharge end at a certain speed, and the material is screened at the same time.
Compared with the above-mentioned sieves, the shaking screen has higher productivity and screening efficiency. The disadvantage is poor power balance. At present, it is rarely used by mineral processing plants, and it is replaced by a more reasonable vibrating screen.