Classification of Pneumatic Conveying Materials Based on Adhesiveness and Effective Anti-Sticking Measures

PART 01: Classification of Materials Based on Adhesiveness

1. Non-Adhesive Materials

Non-adhesive materials refer to those that hardly adhere to the pipeline walls during pneumatic conveying. These materials have ideal flow properties and do not easily stick to the pipeline, ensuring good conveying efficiency. Common non-adhesive materials include certain metal powders and glass beads.

2. Weakly Adhesive Materials

Weakly adhesive materials are those that exhibit some degree of adhesion to the pipeline walls during pneumatic conveying, but the adhesive force is relatively weak. These materials show slight adhesion during conveying but typically do not cause severe sticking issues. Common weakly adhesive materials include some dry powders and grains.

3. Moderately Adhesive Materials

Moderately adhesive materials are those that show noticeable adhesion to the pipeline walls during conveying. These materials have stronger adhesive properties and are prone to causing sticking issues within the pipeline, affecting the normal conveying process. Common moderately adhesive materials include certain chemical powders and ore powders.

4. Highly Adhesive Materials

Highly adhesive materials refer to those with extremely strong adhesive properties during pneumatic conveying. These materials have significant adhesive force and can easily cause severe sticking issues, even leading to blockages within the pipeline. Common highly adhesive materials include certain sticky polymers and pasty substances.

PART 02: Methods to Prevent Material Sticking in Pipelines

1. Choosing Suitable Pipeline Materials

Selecting appropriate pipeline materials can effectively reduce the friction between the material and the pipeline wall, thereby decreasing the likelihood of adhesion. Generally, for moderately and highly adhesive materials, it is advisable to choose pipeline materials with a smoother and more wear-resistant inner surface, such as polyethylene and polytetrafluoroethylene.

2. Controlling Gas Velocity

Properly controlling the conveying gas velocity can reduce the friction between the material and the pipeline wall, decreasing the chances of adhesion. If the velocity is too high, it increases the likelihood of adhesion; if it is too low, the material tends to settle, also leading to sticking issues. Therefore, during pneumatic conveying, it is essential to adjust the gas velocity reasonably according to the material's adhesive properties and the pipeline's diameter.

3. Using Suitable Anti-Adhesion Coatings

Applying an appropriate anti-adhesion coating on the inner surface of the pipeline can effectively reduce the friction between the material and the pipeline wall, thereby decreasing adhesion. Common anti-adhesion coating materials include polytetrafluoroethylene and polystyrene.

4. Regular Pipeline Cleaning

Regular cleaning of the pipeline can effectively remove the material adhered to the pipeline walls, preventing sticking issues. The frequency and method of cleaning should be determined based on the specific adhesive properties of the material and the pipeline usage conditions.

5. Using Suitable Conveying Gases

Selecting appropriate conveying gases can reduce the friction between the material and the pipeline wall, decreasing the likelihood of adhesion. In pneumatic conveying processes, commonly used conveying gases include air and steam, and the choice should be based on the adhesive properties of the material.

In conclusion, pneumatic conveying materials can be classified into different categories based on their adhesive properties. In practical applications, we should select suitable anti-adhesion measures according to the specific material characteristics to reduce adhesion, ensuring the normal operation of pneumatic conveying. By thoroughly understanding the adhesive properties of materials and implementing targeted anti-adhesion measures, we can effectively solve the issue of material sticking in pipelines.