Key Benefits

  • High flexibility and efficiency
  • Precise control, maximising product quality
  • Reliable processing of very small grain sizes
  • High availability and advanced design

Efficient and flexible calcination

Multiple Hearth Furnaces (MHF) are ideal for processing extremely fine-grained material. They allow for the temperature profile to be precisely controlled, enabling you to create the best quality product. In addition to energy and maintenance, you also save on space in your plant through an efficient and streamlined workflow: Drying, devolatilizing, calcining, reduction, oxidization – our MHF does it all.

An MHF is a furnace built from a number of round hearths stacked on top of each other. It is excellent for thermally processing a large volume of raw materials. The hearths make for different zones or levels within the cylindrical furnace, fitted with a hole on top and on the bottom to allow material to pass through. Each of them fulfils a different purpose in the calcination process. 

Since each of the hearths is a separate zone, a different part of the process happens in each one. Material is fed from the top. Rotating rabble arms continuously move over the ore and mix it, ensuring a steady progression as they expose previously covered material to the heated air within the furnace. Thoroughly heated material moves through the hole at the bottom of the hearth and into the next one. This continues until the calcination process is finished and the material emerges at the bottom of the MHF. 

The heating happens via gases that oxidize at the bottom. Being less dense than air, they flow upwards inside the furnace encasing the hearths, against the descending material. Thus, the hearths at the top of the furnace dry and heat it while the gases ignite and oxidize the material in the lower hearths. In a well-insulated furnace, the gas is enough to work with large amounts of raw material and you require no external heating, unless the material is particularly wet. 

Exceptional control and savings 

Our Multiple Hearth Furnaces allow you to closely monitor and control the temperature profile within the individual hearths. In practice, that means maximum production and quality control and thus the efficiency we strive for in our business. In addition to the aforementioned savings on energy usage, our MHFs bring you yet another competitive edge: less space requirement. Since the hearths are stacked on top of each other, you need less floor space to install them, giving you more room for other products. You could even put them on beams to allow other equipment like conveyor belts to run underneath them. 

Fully customizable to your individual needs 

We know that no two production plants are alike, and every plant has specific requirements that cannot be fulfilled with run-of-the-mill products. Our solution to this: a customizable design. We can build your Multiple Hearth Furnace, so it fits you exactly, using material analyses, laboratory test procedures, computer simulations and complex calculations to configure a user-optimised plant. Our R&D Centre will prove to be your trustworthy partner in developing and implementing a customised, innovative and reliable design to meet your needs. 

The superior stage kiln

Our Multiple Hearth Furnace offers a number of unique benefits that will give you a competitive edge, streamline your process and offer the most efficient solution to all your calcination needs. With its high flexibility, reliability and availability, our MHF is the best pyrolysis furnace in the market.

High flexibility and efficiency
Our MHFs are ideally suited for use in the calcination process of raw material, especially for applications that require particularly specific elements. The daily output of a Multiple Hearth Furnace system can be as much as 400 metric tons. 
Precise control of the temperature profile (+- 5°C) for maximum product quality
To further enhance efficiency and ensure the maximum product quality, you can control the temperature profile inside each zone of the stage kiln with high precision. 
Reliable processing of very small grain sizes
Our MHFs are suitable for very fine materials with a grain size of 0-40 mm. The risk of product this small slipping through the cracks and not being processed correctly is very real, but the design of our systems prevents this from happening. 
High availability and advanced design
Consisting of a steel shell with a refractory lining, refractory-lined hearths, a supporting structure, a furnace top platform, and a central shaft with the powertrain, our Multiple Hearth Furnaces are designed to be precise and require low maintenance. You can always be sure of excellent heat transfer between the material and gas phase that also allows you to use some of the cooling air as preheated combustion air, further ensuring efficiency. 

Unique features for optimised calcination

With decades of experience in manufacturing calcination furnaces, we know your specific needs and can offer you a Multiple Hearth Furnace with a number of key features. These are designed specifically to create a furnace capable of calcining large amounts of material while retaining maximum flexibility and efficiency for you.

The first step our MHF fulfils during calcination is drying the materials. We created it to be able to process and dry even those materials with a moisture content above 50%. Pre-drying them is not necessary, saving you time and energy.

Depending on the quality targets, calcination of refractory-relevant minerals takes place from 400 – 1100°C. The stage kiln is ideally suited to this application, especially where very low or precisely defined loss on ignition, a particular surface, specified residual CO2 values, and high product reactivity are required. The daily output of the system can be as much as 400 metric tons. It is suitable for very fine materials with a grain size of 0 – 40 mm.

To ensure a long service life with minimal maintenance, the MHF is insensitive to quality fluctuations in the material used. You can retain a steady flow of raw material without being concerned that quality differences will negatively affect your final product.

Whether your goal is to oxidize or reduce your material by the end of the process, the MHF makes both modes possible. It is also suitable for both exothermic and endothermic processes, even in combination, and suitable for liquid and gaseous fuels, including low-calorific gas.

Finally, this pyrolysis furnace ensures that you will not lose any of your product: 100% of the filter dust can be recycled. 

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