How does pneumatic conveying improve the processing of circular economy materials?

The handling of circular economy materials places demands on transport systems that traditional solutions cannot always meet. Materials can be hot, abrasive, fine-grained or damp, and their behaviour varies considerably from one process to another. Pneumatic conveying offers a workable solution to these challenges when the system is carefully designed based on the actual properties of the material. In this guide, we go through four steps that enable a pneumatic conveying system to operate reliably as part of the handling of circular economy materials.

A pneumatic conveying system moves material through a closed pipeline using compressed air, making it a dust-free, hygienic and easily automatable option. These features are particularly highlighted in the processing of side streams, where the material can be fine dust, hot slag or battery material requiring precise dosing. Read more to pneumatic conveying solutions and see how the system can be tailored precisely to the needs of your process.

Identify the material properties before selecting the system

The design of a pneumatic conveying system always starts by determining the material properties. This phase is the foundation of the whole process, as incorrect input data easily leads to an undersized or pressurised system that wears out quickly or clogs. Ready-made reference data does not always exist for circular economy materials, so material characterisation must be carried out carefully.

Before starting the design, determine at least the following material properties:

• Particle size and particle size distribution and the potential fines percentage
• Bulk density and the condensed density
• Moisture content and the tendency of the material to bind moisture
• Temperature in the process and at the material feed point
• Consumability, such as hardness and abrasiveness index
• Fluency and the tendency of the material to sinter or lump

Once the properties of the material are known, it is possible to assess whether the material is suitable for pneumatic conveying at all, and which operating principle should be used to implement the system. For example, hot and abrasive metallurgical slag requires a different approach to fine-grained battery material. At this stage, it is also worth assessing whether material-specific preliminary testing is required before final design.

Select the correct pneumatic system type for the material

Once the material properties are known, a suitable conveying method can be selected. Pneumatic conveying can be implemented using two main principles: dilute phase conveying or dense phase conveying. The choice directly affects the system's energy consumption, wear and tear, and suitability for different materials.

Hover transport

In pneumatic conveying, material travels through pipework at high air velocity as a dilute phase. The method is particularly suited to light, free-flowing materials and short transfer distances. The structure is simple and cost-effective, but the high material velocity increases pipe wear and can fracture fragile granules.

tulip transport

In dense phase pneumatic conveying, the material moves through the pipeline as small plugs at a lower air velocity. This significantly reduces pipeline wear and material degradation, making it a better choice for abrasive, fragile or heavier materials, as well as for longer transfer distances. In addition, dense phase conveying uses less compressed air, which reduces operating costs.

Select the system type based on the following criteria:

1. If the material is abrasive or fragile, favour slug flow.
2. If the transfer distance is long (over 50 metres), slug conveyance is usually more energy-efficient.
3. If the material is light and free-flowing, air-slide conveying may be a sufficient solution.
4. If the process has ATEX requirements, ensure that the chosen system meets them.

A good starting point is that plug transport is suitable for most circular economy materials, as side-stream materials are often abrasive or challenging due to their varying properties. Do you need more information on choosing the right method? Contact us and let's go through the properties of your material together. Read also in more detail, which pneumatic conveyor is suitable for fine-grained materials.

Integrate the pneumatic conveying system as part of the overall process

The pneumatic conveying system does not operate in isolation, but is part of a broader process entity. Successful integration requires that the system is matched with feed devices, the receiving silo, filter solutions and the plant's automation. Processes in circular economy projects can be multi-stage, so the interfaces with other equipment must be carefully designed.

Review the following integration points when designing the system:

1. Feed point: Ensure that the feeder is suitable for the material properties. Hot or damp material may require a special solution prior to the pneumatic conveyor.
2. Pipeline route: Plan the route so that the number of bends is at a minimum. Every bend increases pressure loss and wear.
3. Receiving silo filter: The silo filter must be dimensioned according to the dusting properties and capacity of the material being conveyed.
4. Automation interface: The pneumatic conveying system can be integrated into the plant's DCS system, making operation fully automated.
5. Security solutions: If the material is explosive or there are ATEX areas in the process, these requirements must be taken into account already in the selection of piping and equipment.

Once the integration points have been reviewed, it is a good idea to check that the entire process chain functions logically: material flows from the feed point through the conveying pipework to the receiving silo without bottlenecks or risks of clogging. Particularly in the handling of side streams, the various stages of the process may involve cooling, screening or storage prior to pneumatic conveying, so the sequence and compatibility of these stages must be ensured. Read more to pneumatic conveying solutions and consider how they fit into your process configuration.

Ensure the functionality of the system through testing

When handling circular economy materials, pre-testing is particularly important because reference data from previous projects is not always available for side streams. The actual behaviour of the material in pneumatic conveying can deviate significantly from theoretical values, and this discrepancy can lead to unexpected issues during the commissioning phase, such as blockages or excessive wear.

Testing can be used to ensure:

• Suitable transport method (suspension flow or plug flow) specifically for this material
• Correct airspeed and pressure to ensure reliable transport
• Behaviour of the material at various moisture contents and temperatures
• Potential changes in the material structure during transport
• Wear of piping and components in practical conditions

Following testing, the sizing is based on actual measurement results rather than solely on calculated estimates. This reduces the risks associated with commissioning and improves the system's operational reliability throughout its lifecycle. For example, ladle slag handling and various metal dusts are typical materials whose sizing benefits significantly from material-specific pre-testing.

Long-term cooperation from design to commissioning and subsequent service ensures that the system evolves according to needs. Not everything can be anticipated at the drawing board, and the actual behaviour of the material is often only revealed in practice. Therefore, it is important that the system supplier has the ability to react to changes even after delivery. Kopar has supplied pneumatic conveying systems for demanding industrial applications for nearly 50 years, and our list of references covers a wide range of different material handling projects. Contact us and tell me what kind of material your process handles, and together we can figure out the best solution.