Calcining - also known as calcination - is a thermal treatment process that uses extremely high temperatures to change the physical and chemical properties of various solid materials, including minerals, metals, and ore. Calcining is used in a variety of industrial applications within the mineral processing, recycling, and manufacturing industries. The process is frequently used to improve electrical conductivity, and to remove chemically bound water and other impurities.

Many calcining processes include additional equipment after a chemical, mineral, or ore passes through the rotary kiln. While not necessary, calciners can be accompanied by a cooling system, designed to quickly cool a material down from the high temperatures experienced during the process, making it easy to quickly package and distribute the end feed for re-use.

Some examples of calcining applications include:

• The removal of water from alumina at temperatures ranging well above 2,000°F. Removing water from alumina makes it possible to manufacture catalysts.
• The removal of water from kaolin, from which calcined kaolin can be used in the production of paper and other similar processes.
• Volatiles can be removed from spent activated carbon, allowing the reactivated carbon to be recycled back to absorption columns with the gold mining industry.
• Removal of mercury from cement kiln dust.