Rotary Kiln Testing in the Innovation Center

This article was co-authored by:

Alex Ebben
Process and Sales Engineer

Carrie Carlson
Technical Writer

Rotary kilns use extremely high temperatures in order to cause chemical reactions or phase changes in material. They are frequently used in the production of the materials all around us, particularly when it comes to advanced materials such as catalysts and absorbents, which require precision processing capabilities.

As such, a significant amount of research and development must first be done to predict how material will behave in a kiln, as well as how the commercial kiln must be designed in order to produce the desired results. This makes rotary kiln testing like that carried out in the FEECO Innovation Center critical to gathering process data and developing the groundwork for a safe, efficient, and effective process.

Why Use Rotary Kiln Testing?

Testing is useful in a multitude of rotary kiln processes. Commonly tested processes include:

There are also many reasons why it may be desirable to conduct rotary kiln testing. Among them:

Commercial Rotary Kiln Sizing & Design

Perhaps the most common reason rotary kiln testing is conducted is to gather the data necessary to size and design a commercial size kiln for an intended application. In this setting, the desired set of product parameters have typically been determined, but the customer needs to know what the rotary kiln and surrounding process will need to look like to reach those parameters.

Product Development

Often times, a customer is looking to develop a new or enhanced product. While this can occur in any industry, a common example is seen in catalyst preparation, where calcination plays a central role in bringing about the desired characteristics of the end product.

In such cases, the FEECO Innovation Center can help to refine product characteristics through testing, as well as produce small samples for use in field trials.

Material Sample During Rotary Kiln Testing

Sample of material pulled from the rotary kiln during testing

Process Confirmation

Testing is also useful in determining if a particular process holds potential for a commercial-scale operation; producers come in with an idea and maybe even a sample of material, which can then be trialed for technical and economic feasibility.

This type of rotary kiln testing is often seen in the reclamation of valuable materials such as metals from wastes. Many waste materials have previously been landfilled despite containing a valuable component, because the value was inaccessible or not recoverable in the waste’s existing form. Advanced thermal processing techniques have opened the door to the recovery of these valuable components, allowing a company to test a material to see if the valuable component could be recovered from the waste material in an economically viable way.

To Test Variable Process Conditions

Another common reason for rotary kiln testing is for the evaluation of alternative processing conditions. Many customers may have an existing thermal system, but are looking to adjust the process, or feel that their current process could be improved upon. Rotary kiln testing in this aspect allows them to try out various process conditions without experimenting on their existing kiln or affecting production schedules.

How Rotary Kiln Testing Works

Testing with rotary kilns is commonly conducted first at batch scale and then at pilot scale.

Batch-Scale Kiln Testing

Batch testing is a cost-effective way to test small sample sizes and gather initial process data, such as time and temperature profiles. Batch test work also helps to define the process parameters needed for continuous pilot-scale testing.

Batch Rotary Kiln Testing

Batch direct-fired rotary kiln used for testing

Pilot-Scale Kiln Testing

Pilot-scale test work is done on a much larger scale than batch testing, allowing for a continuous process loop to be tested, and commercial process conditions to be simulated.

Pilot-scale rotary kiln used for testing

Pilot indirect-fired rotary kiln used for testing

During both batch and pilot testing, solid samples can be regularly withdrawn from the test kiln in order to determine the material chemistry and physical properties of the material at various intervals. Material characteristics such as those listed below are commonly analyzed to ensure a product is meeting desired specifications:

    • Flowability
    • Compression strength
    • Bulk density
    • Crush strength
    • Chemical analysis

Gathered process data can then be used to produce the desired product specifications and aid in process scale-up, establishing parameters and conditions such as:

    • Residence time
    • Kiln slope
    • Temperature requirements
    • Kiln RPMs
    • Emissions
    • Feed rate

Available Rotary Kiln Testing Equipment

Both direct-fired and indirect-fired kilns can be tested in the FEECO Innovation Center, at both batch and pilot scale. All kilns are capable of testing co-current and counter-current air flow configurations, with a variety of optional equipment available to accommodate various process needs. Optional testing equipment includes:

      • Combustion chamber
      • Afterburner
      • Baghouse
      • Wet Scrubber
      • Removable flights, dams, and bed disturbers


A thorough testing program such as those offered by the FEECO Innovation Center is vital to developing a safe and successful rotary kiln process. From batch testing, to process scale-up, the Innovation Center is equipped for all of your rotary kiln testing needs, whether you are looking to establish a new process, develop a new product, or improve your existing operation.

FEECO then uses the data gathered during testing to engineer and manufacture a custom rotary kiln according to the necessary specifications. For more information on rotary kiln testing or our custom rotary kilns, contact us today!






About the Authors . . .

Alex Ebben is a Process Sales Engineer and thermal processing expert.

More About Alex

Carrie Carlson is a technical writer and visual designer.

More About Carrie