What is a Cement Kiln?
A cement kiln is a specialized kiln used in the production of cement. It should not be confused with kiln cement, a heat-resistant material which is used to patch the kilns used in pottery production. Few people have an opportunity to interact with a cement kiln in the course of their lives, although they may use cement products every day. Upon visiting a cement kiln, the first thing that people notice is usually the size, with cement kilns being designed for continuous processing of huge volumes of raw materials. Cement kilns are used in the production of so-called “hydraulic cements,” cements which are mixed with water to create a material which can be used for binding. Portland cement is probably the most famous form of hydraulic cement, although a number of other types of cement can be made in a cement kiln. Many people are familiar with cement in the form of concrete, a material made by mixing an aggregate such as crushed rock with cement to form a very durable, strong mixture. Th
A typical cement kiln is a huge cylindrical furnace 12 to 25 feet in diameter and 450 to 1,000 feet in length. Kilns are set on a slight incline and rotate from one to three revolutions per minute. Cement kilns can process up to 200 tons of raw materials such as limestone, clay, and sand per hour. The temperature inside the kiln can exceed 2,700F. To reach this high temperature a large amount of fuel is needed. Twelve tons of fuel can be burned in an hour. The raw materials move through the kiln until a chemical reaction occurs, and a new compound called “clinker” is formed. The clinker is then cooled and mixed with gypsum. The gypsum and clinker are ground into a powder that becomes cement. The intense heat of the combustion process separates the fuel into organic and inorganic components. The organics are consumed as fuel and the various inorganic compounds either become part of the cement product or are collected in air pollution control devices. The most commonly used kiln fuels ar
