Coating Drums vs. Ribbon Mixers - FEECO International

As products become more specialized and the demand for quality rises, coatings are becoming increasingly more important in industries working with bulk solids. Whether intended to reduce dust, mitigate caking, or enhance performance, the ability to coat granules and other particles gives producers greater control over how their products look, behave, and perform.

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Coating may be carried out using one of several devices. Oftentimes, and particularly in the fertilizer and soil amendment industry, the choice comes down to a coating drum or ribbon mixer. While both types offer an effective coating option, there are some settings where the coating drum provides a better approach to coating.

Here’s a look at these two types of coating equipment, and when it makes sense to choose a coating drum over a ribbon mixer.

About Coating Equipment

Coating equipment selection is just as important as the coating itself. The type of equipment chosen can have implications on critical aspects of the process and product, such as retention time, throughput, and even coating uniformity.

Both coating drums and ribbon mixers, also known as ribbon blenders, offer an effective coating solution in many different settings, but they each operate a little differently. In choosing between the two, it’s important to understand the fundamental differences between them.

Note: A spray system mounted above a belt conveyor is another common approach to coating. However, this produces inferior results due to the significantly uneven distribution of coating and for this reason, has not been included here. For more information on how coating drums outperform belt conveyors, see our article, Improving the Fertilizer Coating Process With a Coating Drum.

The Coating Drum

A coating drum is a type of rotary equipment. Granules or particles are fed into the drum, which is typically set on an incline to help move material through the unit. A spray system distributes the liquid coating over the bed of material as the drum rotates. The rotation of the drum causes the granules to tumble and roll in the bed as they move through the unit, causing the coating agent to evenly distribute throughout the bed onto each granule.

The Ribbon Mixer

A ribbon mixer is a type of horizontal mixer. Granules or particles are fed into one end of the mixing trough, and a centrally mounted agitator, typically in the design of helical “ribbon(s)” helps to move material through the unit while also promoting a mixing action to distribute the coating throughout.

When to Choose a Coating Drum

Coating drums boast several advantages that make them the preferred device in a variety of settings. Most notably, coating drums are chosen over ribbon mixers when:

A Long Retention Time is Needed

The most common reason for which a coating drum is selected over a ribbon mixer is when the process demands a long retention (also known as residence time) – the amount of time the material must be processed in the unit to reach the desired results. A longer retention time is sometimes needed to accommodate a chemical reaction or the absorption of an additive.

While in some settings the coating drum’s size may be considered a disadvantage, in many settings, it is its size that offers this distinct advantage; coating drums can offer a significantly longer retention time compared to ribbon mixers, often doing the work of what would otherwise require multiple ribbon mixers.

The Process Has a High Throughput

Also because of their size, coating drums can handle a much higher throughput compared to ribbon mixers, making them ideal in high-capacity settings such as potash processing plants.

The Product Requires Gentle Handling

Coating drums also offer the best coating solution when the material to be coated is fragile or requires gentle handling. This is because coating drums impart a gentle rolling action, in contrast to the forced “pushing” movement that occurs in the ribbon mixer. Impact forces such as those that occur in the ribbon mixer tend to break down fragile particles. Similarly, pinch points within the mixer can also lead to product breakdown.

As such, when processing any particles that are fragile or in a wet state where deformation could occur, a coating drum offers the best solution.

Maintenance is a Concern

Due to their low maintenance requirements, coating drums are also the device of choice in settings where downtime must be kept to a minimum.

Ribbon mixers tend to have higher maintenance and cleaning requirements than coating drums, requiring ribbon placement as needed.

Another advantage in terms of maintenance is that the maintenance required of a coating drum typically occurs on the drum’s exterior components, meaning operators usually have a visual indicator of when maintenance is necessary. In contrast, the ribbon mixer’s maintenance requirements occur on the unit’s interior and are therefore often not discovered until the unit has been shut down.

The Material is Heat Sensitive

Because a ribbon mixer uses mechanical action to distribute the coating and move material through the unit, frictional forces can generate a slight increase in temperature. In most cases this is not a concern, but when working with materials that are sensitive to heat, the coating drum is the preferred type of equipment to mitigate the potential for product degradation due to heat.

Confirming Coating Drum Feasibility

The coating of granules can be a highly specialized endeavor; diversity in both granule and coating characteristics creates an endless set of operating conditions required to reach specific product quality.

Those unsure of whether or not a coating drum would work for their intended operation can take advantage of testing facilities such as the FEECO Innovation Center. Here, producers can test coating feasibility with their specific coating and material to not only confirm proof of concept, but also to gather the process data necessary for commercial-scale equipment design and scale-up of the process.

The FEECO Innovation Center is unique in that it allows for coating drum testing in isolation, or as part of a larger agglomeration/granulation and drying process.

Conclusion

While coating drums and ribbon mixers are often compared side-by-side in coating equipment selection, recognizing their many differences is critical to selecting the most appropriate device for the application at hand. When a long retention time or gentle handling are needed, as well as when the process has a high throughput, can’t afford downtime, or the material is sensitive to heat, coating drums provide the best option.

FEECO engineers and manufactures custom coating drums to meet specific processing requirements. In addition to equipment design and parts and service support, we also offer testing capabilities to support coating operations. For more information on our coating drums and services, contact us today!

In today’s topic, we will find out the difference between a ribbon blender and a paddle mixer.

What is ribbon blender?

The ribbon blender is a horizontal U-shaped design that is perfect for blending powders, liquids, and granules, and it can combine even the smallest amount of material in big quantities. Construction, agricultural chemicals, food, polymers, pharmaceuticals, and other industries can all benefit from a ribbon blender. For a more efficient procedure and output, a ribbon blender offers a variety of mixing options that are extremely scalable.

What is paddle mixer?

No gravity mixer is another name for a paddle mixer. It’s commonly used to combine powders and liquids, as well as granular and powders. Food, chemicals, pesticides, feeding supplies, batteries, and other products are all covered by it. It has a high-precision mixing that reacts to the components and combines it precisely, regardless of its gravity, proportion, or particle density. It produces part fragmentation by adding fragmentation equipment. The mixer can be made of a variety of materials, including 316L, 304, 201, carbon steel, and so on.

In addition, each product has its own set of features.

Ribbon Blender Features:

-A well-welded connection is present in all parts.

-The tank’s interior is fully polished, with a ribbon and shaft.

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- Stainless steel 304 is used in all of the parts.

- When mixing, there are no dead angles.

- It has a spherical shape with a silicone ring lid.

- It has a secure grid, an interlock, and wheels.

Paddle Mixer Features:

1.highly active: rotate backwards and release materials in different directions. The mixing time is 1 to 3 minutes.
2.High mixing uniformity: The hopper is filled using a compact design and rotational shafts, producing a 99% mixing standard.
3.Low residue: an open-type discharging hole with only a 2–5 mm gap between the shafts and the wall.
4.No Leakage: The revolving axle and discharge hole are protected by a patent-pending design.
5.Entirely clean: fully welded and polished procedure for the mixing hopper without any fastening parts such as screws or nuts for the mixing hopper.
6.Stainless steel is used throughout the machine, except for the bearing seat, giving it a sleek appearance.

The structure of each mixer:

Except for the agitator, all the components are the same.

Ribbon blender

Paddle mixer

The working principle of each differs:

Did you know there are two ribbon agitators in a ribbon blender?

What is the efficiency and effectiveness of the ribbon blender?

-The ribbon blender has a U-shaped chamber and a ribbon agitator for well-balanced ingredient mixing. The inner helical agitator and the outer helical agitator make up the ribbon agitator. When carrying the ingredients, the inner ribbon carries the ingredients from the middle to the outside, while the outer ribbon carries the ingredients from two sides to the center. The ribbon blender reduces the amount of time it takes to mix while also improving the mixing result.

-A paddle mixer consists of paddles. Paddles at different angles carry materials from the bottom to the top of the mixing tank. Various sizes and densities of the components have various impacts on producing a homogenous mixing result. The volume of the product is shattered and combined in a sequential way by the revolving paddles, forcing each component to flow through the mixing tank fast and intensively. 

It also varies in terms of material and application:

Ribbon blender is commonly used for dry solid blending, liquid materials and is used in the following applications:

Pharmaceutical industry: mixing for powders and granules.

chemical industry: metallic powder mixtures, pesticides, herbicides, and many more.

The food processing industry: cereals, coffee mixes, dairy powders, milk powder, and many more.

Construction industry: steel preblends, etc.

Plastics industry: mixing of masterbatches, mixing of pellets, plastic powders, and many more.

Polymers and other industries.

Many industries also are now using ribbon blenders.

Paddle mixer is useful in many industries such as:

Food industry- food products, food ingredients, food additives, food processing AIDS in various fields, and the pharmaceutical intermediate, brewing, biological enzymes, food packaging materials are also mostly used.

Agricultural industry- Pesticide, fertilizer, feed and veterinary medicine, advanced pet food, new plant protection production, cultivated soil, microbial utilization, biological compost, and desert greening.

Chemical industry- Epoxy resin, polymer materials, fluorine materials, silicon materials, nanomaterial, and other rubber and plastic chemical industry; Silicon compounds and silicates and other inorganic chemicals and various chemicals.

Battery industry- Battery material, lithium battery anode material, lithium battery cathode material, and carbon material raw material production.

Comprehensive industry- Car brake material, plant fiber environmental protection products, edible tableware, etc.

That would be the difference between a paddle mixer and a ribbon blender. Hopefully, it will help you choose the best suit for your products.

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Post time: Feb-23-