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Material blockage in silos: Causes and solutions

May 13, 2025

Silos play a crucial role in concrete batching plants, facilitating the storage and continuous supply of materials such as cement, fly ash, and additives. If you have worked with silos for some time, you will understand that they can be both simple and challenging. Some days, they function perfectly, but on others, you might face material blockages that halt material flow.

Material blockage in silos can significantly hinder your production, whether it involves cement or other powdered substances. In this article, Dai Nam PH analyzes the causes of silo blockages and provides practical solutions to help maintain smooth operations while minimizing costs.

Causes of material blockage in silos

Material blockage in silos often occurs during the storage and handling of fine, powdery materials. Here are the most common causes:

1. High humidity inside silos

Moisture absorption and caking: Cement and fone powders have a high moisture absorption capacity, leading to material caking. When humidity levels rise or water infiltrates the silo, the material becomes sticky, making it difficult to discharge.
Increased friction and adhesion: high moisture content enhances friction between the material and the silo walls, causing material to adhere to the interior surfaces. This reduces the silo’s effective storage capacity and increases the risk of blockages.

2. Inefficient silos design

Insufficient hopper sloper: If the cone angle of the silo hopper is not steep enough, the material will not flow freely, resulting in blockages.
Rough interior surface: An uneven interior surface inside the silo can create points where material accumulates and adheres, leading to blockages.
Improper outlet size: A discharge outlet that is too small or incorrectly increasing the likelihood of clogging.

3. High material cohesion

Tendency to form arching and ratholing: Some types of cement or fly ash have high cohesion, making them prone to forming arching effects that obstruct material flow.
Material build-up silo walls: Over time, materials can stick to the silo walls, reducing the usable storage volume and contributing to blockages.

4. Improper silos usage

Overlading the silo: Exceeding the silo’s design capacity can exert excessive perssure on the structure, leading to material compaction and blockages.
Lack of regular inspection and maintenance: Failure to conduct routine silo inspections and maintenance can result in the accumlation of old material, reducing operational efficiency and increasing blockages risks.

Effective solutions to prevent material blockages in silos

1.Using a silos vibration system

The silos vibration system utilizes internal or external vibrators to generate mechanical vibrations. The vibrations help breal material adhesion, preventing the formation or “arching” and “ratholing”, ensurong a continuous material flow.

How to install and use effectively to prevent blockage:

Select the right vibrator: Choose the appropriate type of vibrator (electric or pneumatic) with sufficient power based on the material properies and silos size.
Installation position: Install the vibrator in strategic locations, partcularly at the silo’s bottom or areas prone to blockage.
Set the vibration frequency: Adjust the vibration frequency and amplitude properly to avoid structural damage to the silo while maximizing efficiency.

2. Applying pneumatic systems to clear material blockages in silos

The pneumatic system uses aeration pads or air nozzles mounted inside the silo walls. When compressed air is released, it fluidizes the material and reduces particle friction allowing smooth flow.

Maintenance guidelines to prevent leaks or malfunctions:

Regular inspections: Frequently check components such as valves and pipelines to detect and fix leaks in time.
System cleaning: Clean aeration pads and air nozzles to prevent clogging due to dust buildup.
Ensure high-quality compressed air: Use air filters to remove moisture and contaminants, preventing system damage.

3. Optimizing silos design

A proper design enhances material flow and reduces material blockage in silos:

Silo slope: Use a 50-degree or steeper angle for gravity-assisted discharge.
Discharge gate optimization:
- Size: Ensure it’s wide enough to prevent clogs but not too large for uncontrolled flow.
- Shape: Use optimized forms like oval or rectangular for better flow dynamics.

Maintenance practices to prevent material blockage in silos

1. Regular inspections and cleaning silos

Frequent silo cleaning: Conduct quarterly cleanings to remove accumulated materials on silo walls and bottom, preventing blockages and maintaining maximun storage capacity.
Check discharge systems and flow-aiding equipment: Regularly inspect discharge valvews, vibration systems and pneumatic components to ensure smooth operation and promptly resolve potential failures.

2. Moisture control

Install moisture control systems: Use humidity and temperature control devices to maintain a dry environment inside the silo, preventing moisture intrusion.
Proper material storage: Ensure materials are stored in dry conditions before entering the silo minimize the risk of caking and blockage due to high humidity.

3. Adhering to proper operating procedures

Avoid overloading the silo: Follow the silo’s design capacity to prevent excessive structural stress and discharge system failures, reducing the risk of blockage.
Maintain a proper discharge schedule: Regularly discharge materials according to a proper schedule to avoid long-term buildup, especially for materials with high adhesion tendencies.

Dai Nam PH – Leading concrete solutions provider in the Philippine Market

Silo blockages are common but entirely preventable and manageable with the right strategies. Implementing solutios such as vibration systems, pneumatic aeration, optimized silo design, and regular maintenance helps ensure a stable material flow and minimizes the risk of production downtime.

With nearly 20 years of experience in Southeast Asia, Dai Nam PH has successfully designed and manufactured silos ranging from 100 to 1,500 tons. We have delivered hundreds of projects, affirming our position as a trusted supplier in the Philippines and across the region. We utilize CNC laser cutting technology and Panasonic robotic welding systems from Janpan, ensuring percision and high product quality. Our shot blasting and thick coating process (120-140 microns) enhances the durability and corronsion resistance of our silos.

With years of experience in the Philippine silo market, we are proud to support you in enhancing the efficiency and quality of your construction projects!

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