Indirect Rotary Calciners

Indirect Rotary Calciners

Range from steam tube rotary dryers/calciners through to high temperature <1,100oC calciners for both oxidative and reducing environment processing. Main mode of energy transfer is radiation and conduction


  • Indirect rotary calciners are designed for numerous processing applications depending on the process requirements.
  • The kilns can be designed for oxidative processes though to reducing processes and can handle fine material size distributions up to 10micron.
  • The kilns can be configured with a single temperature zone or multiple zones and can operate up to 1,100degC without distortion to the selected construction material.
  • Materials of construction can range from painted mild steel, through to various grades of stainless steel to special alloys depending on the processing environments and conditions.
  • Heat sources range from steam, thermic oil, electric gas and liquid fuel burner systems
  • All equipment is tailor designed to suit the processing requirements.
  • A unique aspect of a Drytech indirect rotary kiln is our unique internal ceramic liner which allows the processing of highly corrosive environments without detriment to the product or equipment.
  • This specific design allows for the process of REE, Hot Acid Leach process and high purity products.
  • Other materials processed: spodumene, graphite, tin, tungsten, vanadium, titanium, REE, soda ash, kaolin, alumina, stibnite to name a few.


Automatic and continuous. Vibrators, screw feeders, rotary airlocks, double flap valves, gravity chutes

Feed Characteristics:

Powders, granules, non-friable agglomerates. Low to high feed rates <45tph

Heat Source:

Electrical, steam, gas, liquid fuel


Product contacts the heated surface of the drum. Special lifters turn the product exposing the new product to the heated surface.

Residence time:

Controllable. Residence time can be altered by varying the speed of rotation of the drum and the drum angle. Fill can be varied. Fills are typically between 5% and 20% of the cross-sectional area of the drum.


Normally induced but depends on the process requirements.

Dust Collection:

Systems can be low dust with minimal separation requirements.

If required cyclones, baghouses, scrubbers, Electrostatic precipitators.


PLC, infrequently solid-state controllers. System controls on discharge temperature. Can modulate energy and feed.


High throughput
Excellent energy utilization for electrical units
Can have zoned temperature profile
Gentle handling
Intimate product contact
High-temperature operation - can be refractory lined.
The unit can have an integral cooling section.


Incorrect seal design can cause leakage
Large real estate required
High temperature can cause damage to certain components