Application of Circular Vibrating Screens in Stone Crushing Plants

Application of Circular Vibrating Screens in Stone Crushing Plants

1. Overview
A circular vibrating screen (also called a YA/YK series vibrating screen) is a screening device that uses a circular motion trajectory. It is widely used in stone crushing plants for size classification, grading, and separation of crushed stone, sand, and gravel.

2. Position in the Crushing Process
Circular vibrating screens are typically arranged in a closed-loop circuit with crushers:

• Primary screening: After primary crushing, the screen removes fine material before it enters the secondary crusher, reducing crusher load.
• Secondary/tertiary screening: After secondary or tertiary crushing, the screen separates products into different size fractions (e.g., 0–5 mm, 5–10 mm, 10–20 mm, 20–31.5 mm).
• Closed-circuit crushing: Oversized material (> required size) is returned to the crusher for re-crushing, while undersized material becomes the final product.

3. Main Functions

• Size classification: Separating crushed stone into different specifications according to particle size.
• Scalping: Removing fines and dirt before crushing to improve crusher efficiency.
• Dewatering (in some cases): Reducing moisture content of sand and gravel products.
• Feeding uniformity: Providing stable and evenly distributed feed to downstream equipment.

4. Working Principle
The screen consists of a screen box, sieve mesh, vibrator (eccentric shaft or eccentric block), spring suspension system, and motor. The motor drives the eccentric shaft through a belt, generating centrifugal force that makes the screen box move in a circular path. Material on the sieve surface is thrown up and moves forward, and particles smaller than the mesh size pass through, while larger particles continue to the discharge end.

5. Key Advantages

• High screening efficiency and large processing capacity.
• Simple structure, reliable operation, and easy maintenance.
• Adjustable amplitude and frequency for different materials.
• Suitable for various materials, including limestone, granite, basalt, river gravel, etc.
• Multiple layers (2–4 layers) can classify several products at the same time.

6. Selection Considerations

• Capacity: Must match the output of the crusher.
• Mesh size: Determined by required product specifications.
• Layer number: Based on how many product sizes are needed.
• Amplitude and frequency: Selected according to material properties and feed size.
• Installation angle: Usually 15°–25° for circular vibrating screens.
• Motor power: Depends on screen size and load.

7. Common Problems and Solutions

• Blinding (mesh clogging): Caused by wet or sticky material; can be solved by adding cleaning devices or reducing moisture.
• Uneven material distribution: Adjust the feed chute or increase the feed width.
• Abnormal vibration or noise: Check springs, bearings, and eccentric blocks; ensure proper lubrication and tightening.
• Low screening efficiency: Check mesh wear, amplitude, and feed rate.

8. Maintenance Tips

• Regularly inspect and replace worn sieve meshes.
• Lubricate bearings and check the eccentric shaft.
• Tighten all bolts, especially those on the screen box and vibrator.
• Check spring condition and replace damaged springs.
• Keep the feed uniform and avoid overload.

9. Conclusion
Circular vibrating screens play a vital role in stone crushing plants by ensuring product size accuracy, improving crushing efficiency, and enabling closed-circuit operation. Proper selection, operation, and maintenance are essential for maximizing productivity and product quality.