When is pneumatic conveying suitable for transferring light and fine recycled materials?

Dilute phase conveying is a form of pneumatic transport in which material moves through a pipeline at high speed in a suspension. It is ideally suited for certain materials, but in the wrong application it can cause excessive wear, material damage, or energy inefficiency. As circular economy projects become more common, more and more industrial facilities face the situation of having to decide whether dilute phase conveying is suitable for transporting their side or waste streams.

In this guide, we go through three steps that will help you assess the suitability of a jetting operation for your own process. By getting familiar with pneumatic transport systems In a broader sense, you get a good foundation for decision-making.

Identify materials suitable for aerial transport

The principle of the liquid transport is based on the fact that the material is kept in constant motion with a high gas flow. This places clear requirements on the material to be transported: it must be sufficiently light and finely dispersed so that it remains suspended in the pipeline and does not collapse or become clogged.

Materials well suited for heavy lifting typically have the following characteristics:

• The particle size is small, usually less than 1 mm
• The density is low, often less than 1,000 kg/m³
• The material flows freely and is not wet or sticky
• The material is not particularly sensitive to decomposition or wear
• The material is not highly consumable for the pipeline

In the context of the circular economy, such materials include fine aggregate material dusts, light mineral dusts, dry sawdust, and certain dry powdered by-products. For wet soils, materials prone to liquefaction, or very abrasive materials, conveyor transport is usually not the best choice. In these cases, bucket or mechanical transport often works better.

Check the suitability of your materials by evaluating these factors:

1. Measure or determine the bulk density and particle size distribution of the material
2. Estimate the material's moisture content and its tendency to form lumps
3. Find out if the material is consumable or fragile, meaning it will easily break at high air speeds
4. Check to see if the material imposes specific requirements, such as the need for an ATEX safety classification due to the risk of dust explosions.

After going through these points, you should have a clear picture of whether the material is inherently suitable for bulk transport or requires more careful consideration or the determination of an alternative method. If there are uncertainties regarding your material's characteristics, do not make a decision based solely on guesswork; proceed to the next step.

Do you want to know which pneumatic conveying method is best suited for your fine-grained materials? Read more about the transport of fine-grained materials and find the right solution for your process.

Evaluate process conditions before choosing hardware

The material properties are just the starting point. The suitability of the crane transport depends equally on the type of environment and the requirements for the transport. Careful assessment of the process conditions before choosing the equipment saves significant time and costs later on.

Key process conditions that affect the suitability of aerial transport are:

• Relocation journey and height difference: Rail transport works well for short and medium distances. In very long transfers, energy consumption increases, and shuttle transport can be a more economical option.
• Capacity: Crane transport is well suited for small and medium-sized capacities. Very large tonnage quantities may require other solutions.
• Material temperature: If the material to be transported is hot, for example metallurgical by-products, the material choices for the piping and components must be made accordingly.
• Dust management and closed system: The coal transport takes place in a closed pipeline, which is an advantage when handling dusty or hazardous materials. Ensure that the separators and filters are properly sized.
• Energy efficiency: Aerial transport uses more compressed air than shuttle transport. Evaluate whether this energy cost is acceptable for your overall process.

Go through the process conditions systematically:

1. Draw or find the pipe route: length, height difference, and possible obstacles
2. Determine the required capacity in tons or kilograms per hour
3. Determine the material's temperature at the time of transport
4. Assess whether the process environment imposes specific requirements, such as an ATEX classification or a high humidity level in the surrounding air
5. Compare the energy consumption of a freight transport compared to other alternative transport methods

Once the process conditions have been clarified, you have sufficient initial information for a preliminary equipment selection. If the conditions are unusual or the material deviates from standard specifications, you need additional assurance before making a final decision. Contact our experts and we go through the circumstances together.

Ensure the functionality of the solution through material testing

Many circular economy projects address materials for which there is no previous experience or reference data regarding their behavior. Even if the material properties and process conditions have been carefully investigated, theoretical evaluation is not always sufficient to provide a reliable basis for sizing. In such cases, material testing before making a final equipment selection is a sensible way to reduce risks.

Material testing can be used to determine:

• How the material behaves in real pneumatic transport
• What speed and pressure level produces the best transport result
• Does the material leak or consume more pipe than expected at high air speed?
• Is fly-towing really a better choice than hose transport for this particular material?
• What are the correct component choices, such as the sizing of separators and filters

The test can be carried out as follows:

1. Provide a sufficient sample of material for testing. The sample should represent the actual process material as closely as possible, including moisture content and particle size distribution.
2. Test the material in a testing facility where real process conditions can be simulated and the efficiency of transportation and the material’s behavior can be measured.
3. Analyze the test results and compare them to the process requirements. Determine whether the capacity, energy, and operational reliability requirements are met.
4. Make the equipment selection based on the test results, not just on theoretical calculations.

Testing is not an extra cost; it is an investment in operational reliability. Especially for new by-products, pre-testing reveals material-specific characteristics that can be prepared for already at the design stage. This reduces the surprises associated with commissioning and improves the overall system’s reliability in the long term.

At the copper testing facility, we have tested a wide range of different side-stream and waste material materials, including fine metal dust and battery materials. Based on the test results, the solution we have designed provides both the customer and the supplier with certainty that the chosen transport method will work in practice. View our case studies and see what kinds of solutions we have provided for similar projects.

Would you like to find out if a flyover transport is suitable for your process? Discover our pneumatic conveying solutions or Get in touch and we go through the material's characteristics and process conditions together.