Which process involves burning a mixture of lime and clay in a rotary kiln?

The correct answer pertains to the production of Portland cement, which is the result of heating a mixture of lime (calcium oxide) and clay (which contains silica, alumina, and other materials) in a rotary kiln. The process begins with the raw materials being finely ground and mixed in precise ratios to form what is known as the raw meal. This raw meal is then subjected to high temperatures, typically around 1400 to 1600 degrees Celsius, in the rotary kiln.

As the mixture is heated, chemical reactions occur, and new compounds form, particularly calcium silicates and other clinker phases, which are essential components of Portland cement. Once the clinker is formed, it is cooled and then ground into a fine powder, resulting in the final product, Portland cement. This cement then serves as a binding agent in various construction materials, including concrete and mortar.

Production of lime, while it involves burning limestone to produce calcium oxide, does not use clay as a component. The production of concrete occurs later, using cement as a key ingredient along with aggregates and water, but it is not a direct result of the burning process described. Mortar production incorporates cement but is not the process of directly burning materials in a rotary kiln as described in the