Techno-Commercial ​​​​​​​


  • By visual observation
  • Kiln shell scanner: Sharp and rapid increase in temperature of rotary kiln shell to a level above 450 degrees Celsius (850 degrees F).
  • Visual observation of loose refractory bricks in the clinker bed of the burning zone.

Possible Effects & Dangers
Severe warpage and damage to the rotary kiln shell.

Suggested Actions to Take
Small red spot, located in the upper transition or near the centre of the burning zone of kiln: Continue normal operation of kiln but -

  1. Start shell-cooling fans in the area of the red spot.
  2. Shorten flame to bring "black" feed over the area of red spot in an attempt to form new coating. (What is ‘Coating’ / ‘Coatability’?)
  3. Maintain normal burning zone temperatures.​
  4. Change kiln-feed chemistry to obtain easier burning mix.

Large red spot, located under or near a kiln tire or in areas where usually no coating is formed: Kiln should be shut down immediately.

Under no circumstances should a water spray be used on the red spot as this could immediately result in severe kiln shell damage.

Preventive Measures

  1. Make sure flame configuration and characteristics are not causing localized coating erosion or continuous, excessive overheating.
  2. Ensure proper refractory installation methods are followed.
  3. Minimize frequency of rotary kiln shutdown and upsets. (More about the ‘Frequency of Rotary Kiln Shutdown’)​
  4. Avoid 'hard' burning mixes (ensure sufficient percent liquid content in mix to promote coating formation).

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How to tackle Red Spot on Rotary Kiln Shell

Here at we have short-listed 15 most common emergency conditions that can be encountered on a rotary kiln and how to tackle with each of these situations. Out of these first and the most common emergency condition for a rotary kiln is appearance of Red Spot On Kiln Shell. The following discussions are brief in a notation format in order to provide the reader with some quick ideas, solutions as how to deal when faced with such a situation. 

Red Spot on Rotary Kiln Shell