Paddle granulator: a key solution for powder flow and industrial performance

Managing compacted powders and solid blocks is a critical challenge across multiple industrial sectors, including chemicals, food processing, pharmaceuticals, and construction.

The impact of powder clumps and lumps on production processes can be considerable, leading to downstream equipment blockages, formulation inconsistencies, and operator safety concerns.

To address these challenges, various industrial particle size reduction solutions are available, including deagglomeration, milling, sieving, and granulation.

In this context, the paddle granulator stands out as a key piece of equipment for delivering precise and efficient particle calibration of powders and bulk materials.

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Pour en savoir plus sur le fonctionnement, vous pouvez consulter cette vidéo explicative :

1.1 Issues with Compacted Powders and Solid Lumps

In many industries, bulk materials undergo physical changes during storage or transport. Factors such as humidity, pressure, and storage duration promote the formation of solid lumps, which impair flowability and downstream processing.

Examples by industry:

• Food industry: products such as sugar, salt, and cocoa tend to form hard lumps when exposed to moisture.
• Chemicals: some polymer powders, resins, and industrial salts compact under pressure.
• Pharmaceuticals: powdered active ingredients may agglomerate, making accurate dosing more difficult.

In such cases, particle size reduction is essential to ensure consistent flow and prevent equipment blockages in production lines.

1.2 Effects of Poor Particle Calibration

Insufficient particle size control can lead to several problems:

• System blockages: solid masses may clog hoppers, conveyors, or feeders.
• Flow disruptions: interlocked lumps may create flow restrictions or complete blockages.
• Poor product quality: uneven powders may affect final product texture. Lumps can interfere with mixing, dispersion, or blending into liquid bases.
• Handling difficulties: oversized lumps in pneumatic conveying lines may cause pipe blockages.

1.3 Techniques for Reducing Bulk Blocks

There are several solutions for treating compacted materials:

• Deagglomeration: breaks down clumps to restore uniform sizing. Knife deagglomerators with dual rotating shafts fragment powder blocks up to 700 mm. Final pieces typically measure under 10 mm, with high throughput rates.
• Granulation: forces material through a sizing grid for consistent output. Paddle granulators allow controlled reduction while minimising fines. Particle size can be reduced to as little as 1–2 mm. Throughput is lower due to the pressing action.
• Milling: transforms powder particles. Unlike granulators, mills (e.g., pin or hammer mills) apply more intense shearing, achieving particle sizes as low as 50 to 100 microns. This is true particle size reduction.

The paddle granulator stands out for its ability to break down lumps while maintaining consistent sizing, without producing excess unusable fines. It is widely used in the chemical and food industries to calibrate materials like salt or sugar after storage.

2.1 How Does It Work?

The paddle granulator is designed to ensure homogeneous sizing of compacted powders within the system. It operates using a single shaft equipped with multiple paddles that force material through a calibrated screen. The screen openings can be adjusted to achieve the desired particle size, typically ranging from 50 mm down to 2 mm.

Unlike deagglomerators, which provide coarse fragmentation, the granulator refines particle sizing without creating excess fines, making it ideal for processes requiring precisely sized products for handling or further treatment.

2.2 Benefits of Paddle Granulators

A major advantage of paddle granulators lies in their ability to deliver precise and uniform particle sizing. The end product maintains a consistent granulometry, avoiding size variation issues in downstream operations.

By limiting fine particles, these units also significantly reduce the risk of clogging in hoppers, feeders, and pneumatic transfer systems.

The machines are also highly versatile, capable of handling both dry and slightly moist products, which makes them suitable for a wide range of industrial applications.

Unlike mills, which may over-reduce particle size and alter physical properties, paddle granulators provide controlled reduction while preserving the integrity of the processed material.

2.3 Typical Industrial Applications

Paddle granulators are widely used across industrial sectors to simplify powder handling and enhance downstream processes.

• Chemical industry: efficient processing of hygroscopic powders and compacted industrial salts, ensuring smooth, unobstructed handling within systems.
• Food industry: used to process materials like salt and sugar to ensure steady, reliable flow throughout production lines.
• Pharmaceutical industry: precise particle calibration is essential for producing tablets and capsules. Paddle granulators provide uniform sizing, enabling consistent dosing and shaping.

With their robust construction and operational flexibility, these machines are a core component in optimising industrial production processes.

3.1 Key Selection Criteria

Choosing a paddle granulator involves evaluating several factors relevant to the production process.

• Product characteristics: hardness, moisture content, and abrasiveness influence the screen type and paddle rotation speed required.
• Throughput and production rate: the equipment must be appropriately sized to meet the plant’s demand without causing slowdowns.
• Hygiene and safety standards: a crucial consideration in the food and pharmaceutical industries, requiring compliance with ATEX and FDA regulations.

3.2 Available Options and Configurations

Paddle granulators are available in standard or bespoke configurations, depending on the requirements of each industrial process.

• Fitted with interchangeable screens to accommodate different particle sizes.
• Option to include Clean-in-Place (CIP) systems for easier maintenance and hygienic compliance.
• Capability to integrate automated control systems for real-time monitoring and improved process efficiency.
• Compatible with other particle size reduction equipment such as sifters and mills.

3.3 Case Study: Chemical Sector – Adhesives and Resin Manufacturing

In the chemical industry, manufacturing adhesives and glues involves handling materials such as resin and natural rubber. When stored in bags, these materials tend to compact and form solid blocks, complicating their feeding into reactors.

Problem: Bags of resin and rubber were compacting into large lumps that clogged the inclined screw conveyor feeding the adhesive reactors. This led to production flow interruptions and lump formation in the mixing phase.

Palamatic Process solution: A bag emptying system equipped with a GR50 paddle granulator and an inclined trough screw was implemented.

Advantages of the GR50 Granulator:

• The granulator’s low rotation speed prevents excessive fine particles from being generated, which could otherwise settle on downstream equipment and affect functionality.
• Facilitates the integration of raw materials into the reactors, ensuring a homogeneous mixture and minimising process interruptions.

Another chemical manufacturer needed to process hygroscopic powders that tended to form lumps during storage. Installing a paddle granulator with an adjustable sizing screen allowed the production of homogeneous powder, improving flow and dosing accuracy. This solution significantly enhanced process fluidity and reduced downtime caused by blockages.

Does the paddle granulator alter the structure of the processed particles?

No, unlike a mill which shears and significantly reduces particle size, the paddle granulator simply restores the original particle size by breaking down compacted blocks without affecting the internal structure of the particles.

What is the difference between a paddle granulator and a deagglomerator?

A deagglomerator performs coarse breaking of blocks into smaller, irregular pieces, whereas a paddle granulator delivers more uniform sizing using a calibrated screen, ensuring a more consistent final product.

What are the main benefits of a paddle granulator compared to a mill?

The paddle granulator breaks down blocks in a controlled manner without creating excess fines, while a mill applies intense shearing and reduces particles to much finer sizes.

What types of powders can be handled with a paddle granulator?

Paddle granulators are suitable for compacted, slightly moist, or hygroscopic powders, commonly used in the food, chemical, and pharmaceutical industries.

How do you choose the right paddle granulator?

Selection is based on several factors:

• Powder properties: hardness, moisture content, and abrasiveness.
• Desired particle size: requires an adjustable sizing screen.
• Production rate: throughput capacity must meet industrial requirements.
• Standards compliance: must meet hygiene or ATEX regulations, depending on the sector.

The paddle granulator is a go-to solution for restoring free-flowing, easily handled powders in downstream processing. By breaking down compacted blocks without altering particle structure, it ensures a smooth production flow and minimises the risk of blockages in dosing and conveying equipment.

Its use not only improves product quality but also facilitates seamless integration into subsequent manufacturing stages.

Thanks to its efficiency and versatility, it is well-suited to a wide range of industrial sectors.

Interested in learning more about integrating a paddle granulator into your process? Contact our Palamatic Process experts for a tailored assessment of your needs.