how to size vibrating screen?

Sizing a vibrating screen involves several steps to ensure that it will efficiently handle the material and meet production requirements. Here's a basic guide:

1. Determine Material Properties: Understand the material you are screening. Key properties to consider include bulk density, particle size distribution, moisture content, and abrasiveness.

2. Screening Capacity: Establish the desired screening capacity. This is usually defined in tons per hour (TPH). Take into account the efficiency required for the size separation.

3. Screening Efficiency: Define the desired screening efficiency. High efficiency means a cleaner product, but it might require a larger screen or a different screen type.

4. Screen Dimensions: Calculate the necessary screen dimensions.

   • Width: It often ranges from 600 mm to 2400 mm.
   • Length: The length is typically 2.5 to 3 times the width.

5. Aperture Size and Shape: Choose the correct aperture size and shape based on the material's particle size and required cut points. Common shapes include square, rectangular, and circular.

6. Decks and Layers: Determine the number of decks (layers) needed. Multiple decks can provide several cuts, with upper decks screening larger particles and lower decks screening finer material.

7. Screening Surface: Select an appropriate screening surface:

   • Wire Mesh: For general screening.
   • Rubber or Polyurethane Panels: For abrasive materials.
   • Perforated Plates: For heavy-duty applications.

8. Vibration Mechanism: Choose the type of vibration mechanism. Options include:

   • Exciters: For larger screens.
   • Vibratory Motors: For smaller screens.
   • Electromagnetic Vibrators: For fine or light materials.

9. Slope Angle: Consider the screen's inclination. An angle between 15° and 25° is common but can vary depending on the application's requirements.

10. Load Distribution: Ensure uniform load distribution across the screen to avoid premature wear and inefficiencies.

11. Support Structure: Ensure the vibrating screen has an adequate support structure to handle its operational stresses.

12. Dynamic Analysis: Conduct a dynamic analysis to verify that the screen will operate within acceptable vibration limits and damping factors.

13. Feeding System: Design or select an appropriate feed system to ensure consistent material flow onto the screen.

14. Vendor Consultation: Collaborate with screen manufacturers to validate your design calculations and to finalize the correct screen for your application.

Practical Example:

If you are operating a coal preparation plant and need a screen to handle 150 tons per hour of material with particle sizes ranging from 0 to 50 mm:

1. Material Properties: Coal, with a bulk density of 800 kg/m³, moderately abrasive.
2. Capacity: 150 TPH.
3. Efficiency: Desired screening efficiency of 90%.
4. Dimensions:
   • Width: 1800 mm.
   • Length: 4500 mm.
5. Aperture Size: 10 mm square openings for primary screening.
6. Decks: Two decks for different size cuts.
7. Surface: High-tensile wire mesh for primary deck, polyurethane panels for the second deck.
8. Vibration Mechanism: Dual vibratory motors.
9. Slope Angle: 18° inclination.
10. Load Distribution: Even feed across the entire screen width.
11. Support Structure: Sturdy frame with rubber isolation mounts.

Consult with a manufacturer to confirm the design and then procure the screen.

By following these steps, you'll ensure that the vibrating screen is properly sized and configured for your specific application.