Kiln

Kiln, any of several kinds of furnace, heated electrically or by the combustion of fuel, used to fire pottery or other ceramic products, to roast ores, or in the production of cement. In modern engineering usage, little distinction is made between a furnace and a kiln, although the term kiln is always applied to the heating units used in ceramics and cement manufacture.

Kilns in general are of two types: intermittent kilns, in which the fire must be extinguished while the kiln is being unloaded and recharged with another batch of material to be fired; and continuous kilns, in which loading and unloading is accomplished while the kiln is lit. Modern kilns are of both types, although the various forms of continuous kilns are particularly suited to mass production manufacture. The two most important types of continuous kiln are the tunnel kiln, in which the material heated is moved through a long combustion chamber or heating zone on carts or conveyors, and the rotary kiln, in which the material is moved through a long, inclined, rotating combustion chamber by the force of gravity. For a description of the operation of specific kilns, see Pottery.