A vibrating screen is named so because its screen body vibrates during operation. Due to the strong vibrations generated perpendicular or nearly perpendicular to the screen surface, fine particles smaller than the screen openings quickly pass through and become the finished product. Vibrating screens have high processing capacity and screening efficiency up to 80%, and are simple in construction, easy to operate and maintain, and consume little power, making them widely used in mineral processing.

There are many types of vibrating screens. While their basic shapes are similar, the components that generate the vibration and their working principles differ. Vibrating screens include eccentric vibrating screens, inertial vibrating screens, and many others.

I. Eccentric Vibrating Screen

An eccentric vibrating screen is named for the high-speed rotation of its eccentric drive shaft that causes the screen to vibrate.

1. Structure of an Eccentric Vibrating Screen: An eccentric vibrating screen mainly consists of a screen frame, screen surface, eccentric drive shaft, discs, and counterweights. The screen frame is made of ordinary steel plate welded into a rectangular outer frame. A perforated screen surface or a woven steel screen surface with appropriately shaped and sized screen holes is fixed on this frame. Rolling bearings are installed between the eccentric drive shaft and the two side walls of the screen frame. The screen is mounted on a foundation at an angle of 15°-25°. There is a disc on each side of the shaft, and counterweights are mounted on the discs.

2. Working process and principle of eccentric vibrating screen: When the eccentric vibrating screen is working, the eccentric shaft rotates continuously. When the eccentricity moves upward, the screen rises, and the material on the screen is thrown up and loosened. When the eccentricity moves downward, the screen descends, and the thrown material falls back onto the screen surface by its own weight. The material is thrown up and fallen multiple times on the screen surface, so that fine particles smaller than the screen holes pass through the screen holes and become the undersize product, while coarse particles larger than the screen holes are discharged from the end of the screen as the oversize product. This achieves the purpose of separating particle groups of various particle sizes into products of different particle size grades.

3. Eccentric vibrating screens experience significant inertial forces during high-speed vibration. To prevent damage to the foundation, a counterweight is installed. The counterweight moves in the opposite direction to the screen’s movement, generating an inertial force equal in magnitude and opposite in direction to the screen’s inertial force, ensuring stable and reliable operation of the eccentric vibrating screen. The distance between the counterweight and the eccentric shaft can be adjusted to meet these requirements if necessary.

Eccentric vibrating screens exhibit rigid vibration. Although the amplitude does not change with the load on the screen, the strong vibrations generated during operation are highly detrimental to machinery and buildings. Therefore, they are rarely used in newly built concentrators. Inertial vibrating screens utilize the inertial force generated by the rotation of an eccentric weight mounted on a drive shaft, causing the screen to vibrate; hence, they are called inertial vibrating screens.

II. Inertial Vibrating Screen

An inertial vibrating screen utilizes the inertial force generated by the rotation of a weight mounted on a drive shaft, causing the screen to vibrate. Therefore, it is called an inertial vibrating screen.

1. Structure of an Inertial Vibrating Screen: Inertial vibrating screens share many similarities with eccentric vibrating screens, such as the screen frame, screen surface, disc, weight, and rolling bearings. The main difference lies in the drive shaft, which is a non-eccentric ordinary shaft, and the screen is elastically supported on a foundation by springs.

2. The drive shaft of an inertial vibrating screen rotates at high speed driven by a motor. The discs and counterweights on the shaft generate significant inertial force during rotation, causing the screen to vibrate at high speed. When the screen moves downwards, the lower springs are compressed; when the screen moves upwards, the springs extend and return to their original position. This process generates continuous up-and-down vibrations, and the screening process is the same as that of an eccentric vibrating screen. Domestically produced inertial vibrating screens are available in pedestal and suspended types. They are also classified as single-layer and double-layer screens based on the number of screen layers. To improve screening efficiency, double-layer screens can also be used as single-layer screens.

3. Inertial vibrating screens have a relatively small amplitude and high frequency, making them suitable only for screening medium to fine-grained materials. Their amplitude varies with the load; a large feed rate reduces the amplitude, affecting processing capacity and screening efficiency. The motor vibrates along with the screen, affecting its lifespan. The screen size should not be too large, therefore, they are only suitable for small to medium-sized concentrators; large concentrators rarely use them nowadays.