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

Specifications:

  • 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.

Description

Feeding/discharge:

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

Exposure:

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.

Extraction:

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.

Control:

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

Benefits:

  • 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.

Limitations:

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