Effective Measures to Address Arching Phenomenon in Cement Silos

Cement Silo Basics

1. What is a Silo in Cement?

A cement silo is a vertical storage structure for bulk cement. It has three main functions:

  • Provides airtight storage: This prevents moisture and contamination.
  • Works with pneumatic systems: It allows for automated feeding.
  • Integrates industrial modules: These include weighing, dust removal, and arch-breaking.

Common Types of Cement Silos:

  • Welded Steel Silos: Best for portability and quick installation.
  • Spiral Silos: Cost-effective for medium-sized plants, ideal for budget-conscious operations.
  • Concrete Silos: Ideal for large-scale storage, suitable for high-capacity needs.

2. How Does a Silo Work?

The material flow process is as follows:

  1. Air pumps fill from the top.
  2. Materials stack naturally in the cone.
  3. Bottom discharge occurs with air fluidization or vibration.
  4. A screw conveyor delivers measured amounts.

Key components:

  • Top dust collector (pulse jet system).
  • Level sensors (radio frequency or radar type).
  • Cone activators (fluidized beds or vibrator motors).
Two images of a cement factory showing different types of cement silos, highlighting the diversity in its production process.

Common Cement Silo Problems

Main Issue: Arching Phenomenon

Warning signs:

✔️ No material flow at discharge (but level shows normal)
✔️ Abnormal pressure rise in pneumatic system (+15% from baseline)
✔️ Unusual vibrations/thumping sounds in lower silo

Industry data:

  • Unresolved arching increases energy use by 25-40%

  • 68% of batching errors come from poor silo flow

Proven Prevention Methods

1. Optimal Silo Design

  • Cone angle: Keep ≥55° (exceeds cement’s natural angle of repose)

  • Outlet size: Minimum 0.2×silo diameter (e.g., 4m silo needs ≥800mm outlet)

  • Surface treatment: Electropolished steel lining cuts wall friction by 30-40%

2. Moisture Control

Critical targets:

ParameterTargetCheck Method
Cement moisture<0.5%Loss-on-drying test
Air dew point≤5°C below ambientHygrometer
Storage RH<60%Data-logging sensors

Actions:

• Install desiccant breathers on vents
• Preheat compressed air to 10-15°C above ambient

3. Flow Promotion Tech

Comparison:

MethodHow It WorksBest For
Air fluidizationLow-pressure air injectionFine powders
VibratorsHigh-frequency agitationMoisture-sensitive blends
Air cannonsPulsed air blastsExisting arch breakup

Maintenance Best Practices

1.Preventive schedule:

  • Weekly: Check discharge area for buildup
  • Monthly: Test air cannon membranes
  • Quarterly: Measure cone wear

2.Material handling:

  • Always use FIFO (First-In-First-Out)
  • Avoid storage beyond 30 days

Emergency Arch-Breaking Steps

1️⃣ Stage 1 (within 30 mins):

  • Fire air cannons (≤3 pulses)

  • Check stable air pressure (0.6-0.8MPa)

2️⃣ Stage 2 (1 hour unresolved):

  • Switch to backup discharge

  • Add flow promoter (0.5-1L per ton cement)

3️⃣ Stage 3 (4+ hours):

  • Manual cleaning (requires confined space permit)

  • Inspect cone liner wear (max allowance ≤3mm)

Technical Q&A

Q: How to choose silo size?

A: Use this formula:

Daily use (tons) × Buffer days (3-7) ÷ Bulk density (1.1-1.3t/m³) = Min. capacity

A: Triple protection:

  • Moisture: Add molecular sieve desiccants to roof vents

  • Lightning: Grounding resistance <4Ω

  • Static: Discharge hose surface resistance <10⁶Ω

Key Takeaways

• Always maintain cone angles >55°
• Monitor moisture like a hawk (<0.5% cement moisture)
• Combine air cannons + vibrators for tough materials

If you need high-quality cement silos or want to learn more, please contact us. Darko will provide you with professional solutions and excellent service!

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