Rotary Kiln

What Is a Rotary Kiln?

A rotary kiln is a heating furnace in which a cylindrical chamber (retort) rotates, and raw materials are fed into the furnace (inside the retort) via a feeding device (such as a screw feeder), where they undergo uniform heat treatment while being stirred. Typically, rotary kilns are inclined slightly from the horizontal, allowing raw materials to be heated while the cylinder (retort) rotates at a gentle speed. At Tanabe, we support a wide range of processes spanning from low to high temperatures (200°C to 2,500°C) to meet the needs of various industries (please contact us individually for details on the applications and processing capacities we can accommodate).

Features of Rotary Kilns

Heat patterns can be customized to meet specific firing requirements

• Since temperature is controlled individually for each zone, you can set heat patterns tailored to the firing requirements of your products.
  [Air Cooling System (Optional)]
  For materials that generate heat during the firing process, an air-cooling mechanism can be installed to ensure stable control and prevent temperature overshoot.
• Heaters are arranged around the entire surface (360°) of the heating section, and by minimizing the distance between the heaters and the retort, this eco-friendly design ensures uniform heat transfer, high thermal efficiency, and minimal heat loss.

Customization Designed to Prevent Contamination

• To minimize contamination from metals such as Fe, we can customize the parts that come into contact with the processed material to be made of special alloys such as nickel. This is a technology we can offer precisely because we are confident in our ability to weld these special materials.

Countermeasures Against Sticky Labels

• We offer seal configurations tailored to our customers' processing needs. For fine materials, we also offer dust collection and dust-proof covers to minimize material scatter around the seal.
  [High-Seal (Optional)]
• Thanks to a unique sealing structure that utilizes carbon materials, continuous firing can be achieved in flammable atmospheres (High-Tightness Seal Patent No. 4150368).
• Its unique sealing structure allows for control of both positive and negative pressure. Under positive pressure, it prevents the leakage of powders and gases. Under negative pressure, it prevents outside air from entering the furnace.

Special Internal Furnace Design

• Special structures can be installed to block the flow of raw materials, thereby maintaining the time the raw materials remain in the heating zone (residence time).

Principles, Structure, and Mechanism of Rotary Kilns

Rotary Kiln Production Method

There are two main types of rotary kilns: batch-type and continuous-type. There are several differences between the two.

Differences in Processing Methods

• Batch method
  
  
  In a batch-type rotary kiln, raw materials (the material to be heated) are processed in fixed-volume batches (a set quantity) at a time. The process involves feeding the raw materials, stopping the kiln once processing is complete to discharge the batch, and then feeding the next batch; this cycle is repeated.
• Continuous
  
  
  In a continuous rotary kiln, raw materials (the material to be heated) are fed continuously and move continuously through the kiln. Since the raw materials are fed into one end of the kiln and discharged continuously from the other end, processing takes place without interrupting kiln operation.

The Difference Between Production Capacity and Efficiency

• Batch method
  Because batch-type rotary kilns have a limited capacity for the amount of raw material they can process at one time, they are suitable for relatively small-scale production.
• Continuous
  Continuous rotary kilns offer high production capacity and efficiency because they allow for the continuous feeding and discharge of raw materials. Continuous operation ensures a consistent raw material flow rate, improving process stability and consistency.

Which type of rotary kiln is best depends on the processing requirements and production goals (please contact us directly for details on the applications and processing capacities that Tanabe can accommodate).

Heating Methods for Rotary Kilns

There are two main differences between the heating methods used in rotary kilns: electric heaters and gas burners.

Electric Heater Type

Electric heaters can typically reach high temperatures, yet they allow for relatively easy control of heating rates and temperature. Another key feature is their ability to maintain a uniform temperature distribution inside the kiln. The furnace atmosphere can be set to atmospheric air (including decarbonized air), oxygen, nitrogen, argon, and other gases.

Gas burner type

The gas burner type utilizes the heat generated by the material being processed as fuel (heat source) for the heat booster. It is an energy-efficient system that utilizes the waste heat generated as an external heat source. Superheated steam (SHS) is suitable for the furnace atmosphere.

Examples of Applications by Temperature Range for Rotary Kilns

Examples of Applications with Operating Temperatures Up to 200°C

• Drying of LiB Cathode Material

Examples of Applications at Operating Temperatures Up to 500°C

• Cleaning and Degreasing of Copper Alloy Machining Chips
• SUS, FC Series: Cutting Chips, Cleaning and Degreasing
• Special Metals — Cutting Chips — Cleaning and Degreasing
• Cleaning and Degreasing of Machining Chips from AL Alloys (AC, ADC Grades)
• Cleaning and Degreasing of Cast Iron Machining Chips

Examples of Applications with Operating Temperatures Up to 1000°C

• LiB Cathode Material Sintering
• LiB Anode Material Sintering
• Sintering of Tungsten Powder
• Catalyst and Ceramic Sintering
• Firing of Magnetic Materials
• Carbon Sintering

Examples of Applications with Operating Temperatures Up to 2,500°C

This will be handled using a carbon heater kiln.

• Sintering of Carbon Materials
• Sintering of WC Raw Material (Tungsten Carbide)
• Sintering of Si-based Anode Materials

Rotary Kiln Product Lineup

Superheated Steam Cleaning and Degreasing System for Aluminum Chips and Other Materials (Reactive Metals)

We safely remove oil and moisture from aluminum chips and other materials (reactive metals)—which are prone to fires and explosions—to ensure stable operations and enhance value. View Product Details

Superheated Steam Cleaning and Degreasing System for Various Types of Metal Chips

Compared to conventional methods (such as direct-combustion systems), we propose a superheated steam system that offers high added value and energy savings. View Product Details

Superheated Steam System for Removing Adhered and Contained Organic Matter from Metal Waste

Even waste containing plastic scraps or high-calorific waste—which is difficult to process using conventional (incineration-based) pretreatment methods—can be safely treated using a superheated steam system. View Product Details

Superheated Steam-Based Deracking System for Aluminum Cans (UBC)

Safely removes surface coatings, deposits, and organic matter from metal resources (including waste and valuable materials). View Product Details

Continuous External-Heated Rotary Kiln (Electric)

From small-scale to mass-production systems, we propose optimal designs tailored to your needs, including the materials to be processed, processing fees, ancillary equipment, and floor space requirements. View Product Details

Medium-Sized Batch-Type External-Heat Rotary Kiln (Electric)

For samples requiring long firing times (4 hours or more), we recommend a batch-type rotary kiln. Similar to a continuous rotary kiln, this system introduces various atmospheric gases into the kiln and fires the raw materials while agitating them. View Product Details

Small-Size Batch-Type External-Heat Rotary Kiln (Electric)

For samples requiring long firing times (4 hours or more), we recommend a batch-type rotary kiln. Similar to a continuous rotary kiln, this system introduces various atmospheric gases into the furnace and fires the raw materials while agitating them. Since it is a compact pilot-scale unit, it is ideal for evaluating the firing of small quantities of high-value-added raw materials. View Product Details

Lineup of Rotary Kiln Auxiliary Equipment

We offer comprehensive engineering solutions tailored to our customers’ needs—covering not only the rotary kiln itself but also everything from raw material cooling systems downstream of the kiln to exhaust gas treatment (deodorization and dust collection) systems. We can also design and manufacture auxiliary equipment on its own, so please feel free to contact us if you have specific auxiliary equipment requirements.

Continuous Rotary Cooler

We provide equipment that cools raw materials discharged from a rotary kiln through heat conduction via a cooling jacket structure. View Product Details

Continuous Screw Feeder

We provide equipment that cools raw materials discharged from a rotary kiln through heat conduction in a trough with a water-cooled jacket. View Product Details

Direct-Combustion Deodorization Furnace (Burner Type)

This is an auxiliary device that uses burners or similar equipment to oxidize and decompose odorous components contained in exhaust gases at high temperatures. View Product Details

Implementation Process

• Based on the customer’s request, we will review the specifications and prepare a quote (if the raw material is one that Tanabe has not handled before, we will conduct verification tests to proceed with the specification review).
• We will provide you with a proposal outlining the equipment specifications and costs.
• Once we receive an order from a customer, we will begin the design and manufacturing process.
• If there are any changes to your order, please repeat steps 1 through 3 above in accordance with the changes.
• After manufacturing is complete, the equipment will be delivered to the site, where installation and commissioning will be carried out, completing the equipment implementation process.

Validation Test

We can conduct validation tests for equipment installation based on your heat treatment needs, whether for research and development purposes (such as product improvement or the development of next-generation powders) or to evaluate the feasibility of implementing a rotary kiln system.

Test Procedure Flow

• Meeting: We will discuss the purpose of the test and your requirements during the meeting.
• Test Plan Development: Based on the results of our meeting, we will develop a test plan that meets the client's needs.
• Incorporation into Equipment Specifications: We will conduct the test in the presence of the customer. We can also accommodate batch testing.
• Test Administration: We will organize the data—such as temperature conditions and processing times—and evaluate how the results compared to the plan.
• Summary of Results Evaluation Data: We will incorporate the test results into the equipment specifications and submit a proposal for those specifications.

List of Validation Tests

After-Sales Service

We will enhance our post-delivery support services for rotary kilns to help our customers create optimal operating environments.

Main After-Sales Services

Scheduled Maintenance
We propose the best maintenance plan tailored to your plant's shutdown period.
・Cleaning and replacing seals
・Verification of the outer tube heater's integrity
・Cleaning and inspecting the furnace for proper functioning
・Cleaning and inspecting the furnace for proper functioning
・Replacing consumables such as rollers, etc.
Spare Parts Sales
We carry a full range of consumables and spare parts necessary for stable operations. We provide recommendations based on equipment diagnostics conducted during routine maintenance.
Support for Renovation Projects
We are currently carrying out renovation work to enhance production capacity and modify the furnace mechanisms in conjunction with a product line changeover, among other measures, in order to achieve further functional improvements.

Frequently Asked Questions

Can I check the quality of the finished product in advance?

Since we have testing equipment at our company, we can verify the quality of the results. After both companies review the detailed test specifications, we will determine whether we can proceed.

Could you also provide proposals for front-end and back-end equipment?

Powder processing requires not only the rotary kiln (heating furnace) itself, but also various upstream and downstream equipment, as well as exhaust gas treatment facilities. Therefore, we offer a wide range of auxiliary equipment tailored to our customers’ needs.

What types of furnace atmospheres are possible?

These primarily include atmospheric air (including decarbonated air), oxygen, nitrogen, argon, and superheated steam. We can also consider other options upon consultation and will determine whether we can accommodate them.

Will you be able to provide maintenance support?

We provide services including routine maintenance, spare parts sales, and modification work. We can also handle projects either exclusively with our instructors or in collaboration with maintenance contractors.

Do you have a track record of shipping products overseas?

We have a proven track record of supplying products to numerous customers in Asia and Europe. We can also supply products to other overseas markets, so please feel free to contact us.

Do you have any testing equipment?

Our company owns two continuous φ300RK kilns (one for special powders), one continuous φ100 kiln, one carbon-heated kiln, and one small batch rotary kiln (φ400), so we are able to proceed directly to validation testing.

Can you make it explosion-proof?

The rotary kiln itself cannot be made explosion-proof. However, it is possible to select explosion-proof versions of some instrumentation and other equipment.

Please tell me the maximum size of a rotary kiln.

The cylinder diameter (retort diameter) is a maximum of φ1,400. The processing capacity is approximately 1,900–2,600 L/h (reference value for the φ1,400 RK model).

What is the maximum temperature it can handle?

Temperatures up to 900°C can be handled using an electric rotary kiln. Temperatures ranging from 1,000°C to 2,500°C can be handled using a carbon-heated kiln.

Is it possible to change the material of the retort pouch?

We carry materials ranging from SUS to other special alloys, so changes are possible. However, we do not carry ceramic materials.