APPLICATIONS & MATERIALS

Rotary kilns are versatile thermal processing machines capable of processing a wide variety of materials. Common applications are for both direct-fired kilns and indirect-fired kilns are listed below.

 

CALCINATION

Calcination refers to the process of heating a material to a temperature that will cause chemical dissociation (chemical separation). This process is used frequently in the creation of inorganic materials, for example, the dissociation of calcium carbonate to create calcium oxide and carbon dioxide.

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THERMAL DESORPTION

Thermal desorption is also a separation process. This process uses heat to drive off a volatile component, such as a pesticide, from an inorganic mineral, such as sand. The component is vaporized at the increased temperature, causing a separation without combustion. In some cases, an indirect rotary kiln would be best for this application, because the volatile chemicals may be combustible. The indirect kiln will supply the heat for desorption, without the material coming into direct contact with the flame.

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ORGANIC COMBUSTION

Organic combustion refers to the treatment of organic wastes with the intent of reducing mass and volume. Organic waste is treated in the kiln, leaving behind an ash with considerably less mass and volume. This allows for more efficient and effective deposit of waste materials into landfills.

 

SINTERING/INDURATION

Sintering is the process of heating a raw material to the point just before melting. This increases the strength of the material, and is commonly used in the proppant industry, where sand or ceramic materials are made stronger.

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HEAT SETTING

Heat setting involves bonding a heat resistant core mineral with another, less heat resistant coating material. Unlike an unheated coating process, here, a rotary kiln heats the coating material to just below liquefaction point, allowing it to coat the heat resistant core more evenly and more securely.

This process is commonly seen in the manufacture of roofing granules, where a mineral such as granite is coated with a colored pigment, producing a product that is both durable and aesthetically pleasing.

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REDUCTION ROASTING

Reduction roasting is the removal of oxygen from a component of an ore usually by using carbon monoxide (CO). The CO is typically supplied by mixing a carbonaceous material such as coal or coke with the ore or by feeding it separately. Examples are the reduction roasting of a hematite containing material to produce magnetite that can be magnetically separated. In the Waelz process, zinc oxide in steel mill wastes is reduced to metallic zinc and volatilized for recovery in the off-gas system.

 

Some of the most common materials for which rotary kilns are employed include:

 

• Activated Carbon

• Alumina

• Catalysts

• Contaminated Soil

• Electronic Waste

• Petroleum Coke

• Phosphate Ore for NPK Kalsul

• Pigments

• Precious Metals

• Proppants

• Specialty Ceramics

• Specialty Chemicals

• Waste Lime Sludge

• Waste Materials

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