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Cement Drying Equipment

Rotary Kiln Dryer

Also known as the Cement Dryer, this heavy-duty rotary drum dryer removes moisture from cement raw materials, slag, coal, and other minerals before grinding or calcination. With drum volumes from 9.0 to 285 m³ and capacities of 1.9 to 76.0 t/h, it is available in direct and indirect heat configurations for any material and moisture level.

9.0-285 m³Drum Volume
1.9-76.0 t/hCapacity
Direct / IndirectHeat Type
1-2%Final Moisture

Product Overview

About the Rotary Kiln Dryer

The rotary kiln dryer — commonly called the cement dryer — is a rotating cylindrical drum used to reduce the moisture content of granular and powdery materials before they enter downstream processes such as grinding, blending, or calcination. In a cement plant, it is most often used to dry limestone, clay, slag, coal, fly ash, and other raw materials and additives that arrive with high moisture.

Wet raw materials reduce grinding efficiency, cause bin blockages, and disrupt the stoichiometry of the raw mix. By passing through the rotary dryer, materials are heated and tumbled in a stream of hot gas, evaporating surface and inherent moisture down to the 1–2% level required for stable raw-mill operation. LIMING dryers handle feed moistures up to 20–50% and deliver uniform, predictable final moisture.

LIMING Machinery manufactures both direct-heat (hot gas contacts material directly) and indirect-heat (heat transferred through the drum wall) dryers, in a wide range of drum diameters and lengths. Robust construction, efficient lifting flights, and well-engineered dust collection ensure low energy use, high evaporation rate, and reliable continuous duty.

Types of Cement Dryers

Dryers are classified by how heat is transferred to the material. LIMING supplies both main types.

Direct Heat Rotary Dryer

Hot combustion gas flows through the drum and contacts the material directly. Highest thermal efficiency and evaporation rate, suitable for most cement raw materials, slag, and coal where direct contact is acceptable.

Indirect Heat Rotary Dryer

Heat is transferred through the drum wall or steam tubes, keeping the material and heating gas separate. Used for dusty, sensitive, or contaminant-prone materials where direct contact would cause quality or emissions issues.

Key Benefits

Advantages of the LIMING Rotary Dryer

Engineered for high evaporation rate, low energy use, and reliable continuous-duty drying.

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High Drying Efficiency

Optimized lifting flights cascade the material through the hot gas stream, maximizing gas–solid contact. Evaporation rates are high, and final moisture is reduced to 1–2% consistently across a wide feed-moisture range.

Low Energy Consumption

Counter-current or co-current gas flow, well-insulated drum, and efficient heat recovery from exhaust gas keep fuel and power consumption per tonne of evaporated water among the lowest in the industry.

Flexible Capacity

20+ drum sizes from 9.0 to 285 m³ cover capacities of 1.9 to 76.0 t/h. Variable-diameter and multi-pass designs let you match the dryer exactly to your material and throughput.

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Robust & Reliable

Thick boiler-steel drum, oversized riding tyres and trunnions, and sealed drive system deliver decades of continuous service with minimal maintenance. Integrated with bag filter for clean exhaust.

Rotary Kiln Dryer Specifications

Select a model based on your material, feed moisture, and required throughput. LIMING can also customize drum dimensions.

Model Drum Dia. (m) Drum Length (m) Volume (m³) Capacity (t/h) Slope (%) Speed (r/min)
RKD-φ1.0×81.086.31.9-2.43-52.8-5.5
RKD-φ1.2×101.2109.02.5-3.13-52.5-5.0
RKD-φ1.5×121.51221.24.5-5.53-52.2-4.5
RKD-φ1.8×141.81435.67.0-9.03-52.0-4.0
RKD-φ2.2×162.21660.812.0-15.03-51.8-3.5
RKD-φ2.4×182.41881.416.0-20.03-51.5-3.0
RKD-φ2.6×202.62010621.0-26.03-51.5-3.0
RKD-φ2.8×242.82414830.0-37.03-51.3-2.6
RKD-φ3.0×253.02517735.0-44.03-51.2-2.4
RKD-φ3.2×283.22822645.0-56.03-51.1-2.2
RKD-φ3.4×303.43027255.0-68.03-51.0-2.0
RKD-φ3.6×323.63232665.0-76.03-51.0-2.0

* Specifications are for reference only. Actual capacity depends on material properties, feed moisture, and hot-gas temperature. Contact LIMING for model selection.

How It Works

Working Principle of the Rotary Dryer

The rotary dryer operates on the principle of convective heat and mass transfer between a hot gas stream and a tumbling bed of wet material. The inclined, rotating drum moves material from the feed end to the discharge end while hot gas flows co-current or counter-current through the drum:

  1. Wet material feed: Wet material (limestone, slag, coal, etc.) is fed continuously into the upper (feed) end of the inclined, rotating drum via a chute or screw feeder. Internal lifting flights pick up the material and cascade it through the hot gas stream.
  2. Hot gas entry: Hot combustion gas from a furnace or kiln exhaust is introduced at one end (co-current: same end as material; counter-current: opposite end). The gas temperature, flow rate, and drum speed are controlled to achieve the desired final moisture.
  3. Heat & mass transfer: As the drum rotates, lifting flights lift and shower the material through the hot gas, exposing maximum surface area. Heat transfers from gas to particle, evaporating surface and inherent moisture. The water vapor is carried away by the gas stream.
  4. Dry material discharge: The dried material, now at the target moisture (1–2%), exits the lower (discharge) end of the drum and is conveyed to storage or the raw mill. Moisture-laden exhaust gas exits through a dust collector (bag filter or cyclone) before being released to the stack.

Rotary Kiln Dryer FAQ

What materials can the rotary kiln dryer handle?
The rotary kiln dryer handles cement raw materials (limestone, clay, marl), slag, coal, fly ash, and various granular and powdery materials with initial moisture up to 20–50%. Final moisture can be reduced to 1–2% or lower depending on requirements. Contact us with your material and moisture data for a tailored recommendation.
What is the difference between direct and indirect heat dryers?
In a direct heat dryer, the hot gas contacts the material directly, offering high efficiency and large capacity — the most common choice for cement raw materials and slag. In an indirect heat dryer, heat is transferred through the drum wall or steam tubes, keeping material and gas separate — used for sensitive, dusty, or contaminant-sensitive materials where direct contact would cause quality or emissions issues.
How much moisture can the cement dryer remove?
Depending on material and model, the dryer can reduce moisture from 20–50% down to 1–2% or lower. The exact performance depends on inlet moisture, material properties (particle size, porosity), hot gas temperature, drum speed, and residence time. LIMING will size the dryer and select operating parameters to meet your target moisture.

Need a Rotary Kiln Dryer for Your Plant?

Tell us your material, feed moisture, and required throughput. Our engineers will recommend the optimal dryer model and configuration.

WhatsApp: +86 153 3380 7511 [email protected]
WhatsApp: +86 153 3380 7511 [email protected]