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Rotary dryers

Metso's rotary dryers are used in a wide variety of applications, especially in minerals processing.

Through a series of specially designed lifters, the rotary dryer showers material through the hot gas stream. By maintaining a low gas velocity, very low particulate carryover occurs, improving product yield.

Rotary dryers are suitable for:

  • Mineral processing, Manufacturing
  • Chemical, Petrochemical, Pharmaceutical

Main benefits of Metso systems are:
  • Simple system
  • Flexability in fuels used
  • Year of experience with all types of dryers
  • Capable of installation anywhere in world
  • True understanding of process conditions
  • In house engineering for custom fit applications

Rotary dryers are slightly inclined cylindrical shells supported by 2 riding rings running on a set of rollers. The kiln has a seal at both ends to prevent leakage in or out of air and material. Rotary dryers are suitable for drying a wide range of materials because of their ability to process materials having considerable variation in size and composition. A rotary dryer uses lifters mounted in the shell to produce a cascade of particles falling through a hot gas stream. The mechanical lifting of the material allows rotary dryers to be used to dry materials ranging from fine filter cake to coarse minerals. It also helps in breaking up lumps, promoting a more uniformly dried material.

The proper design of a rotary dryer is based upon several key factors. The dryer diameter determines the gas velocity. Lifter design determines how the material will fall through the gas stream. When designed correctly, the full width of the dryer becomes a shower of material. Chains may also be used when processing very wet material to improve heat transfer. Dryers are also designed for either parallel flow or counterflow. Metso uses real-time modeling programs to simulate the lifter design for optimum performance.

Direct rotary kiln dryers are the most versatile and simplest form of drying. The kilns specifications are determined by the material, how much drying, and how long must it be in the drying process. These dryers are suited for material that are not required to be isolated from a burning system. Typical direct rotary kiln dryers also run some level of oxygen in the system.

If your application does require isolation or an inert atmosphere see Indirect or steam dryers.

Important aspects to look at are:
What is the material?
What is the size and weight of the material?
What is the maximum temperature?
What is the quantity required to be dried?
What are the starting and ending moistures?

We build rotary dryers ranging up to 5.5 meters in diameter. We've built over 4,000 rotary kiln dryers around the world under the brand names of Stansteel, Allis-Chalmers, Kennedy Van Saun, MPSI and Armstrong Holland.


Brochure Fluid Bed and Rotary Dryers and Coolers EN (879 kB) PDF