Coal & Cement
The cement industry requires energy to produce cement and coal is an important source of the energy needed.
Cement is critical to the construction industry – mixed with water, and gravel it forms concrete, one of the key construction materials available today. Varying the mix of cement, sand and aggregate enables concrete to be used in a range of applications. Products can be designed, coloured and shaped to accommodate a variety of environmental conditions, architectural requirements and to withstand a wide range of loads, stresses and impacts.
Over 3.3 billion tonnes of cement were consumed globally in 2010. This is 22% more than in 2007. China's cement consumption alone reached over 1.8 billion tonnes, or 38% more than in 2007.
What is Cement?
Cement is made from a mixture of calcium carbonate (generally in the form of limestone), silica, iron oxide and alumina. A high-temperature kiln, often fuelled by coal, heats the raw materials to a partial melt at 1450°C, transforming them chemically and physically into a substance known as clinker. This grey pebble-like material is comprised of special compounds that give cement its binding properties. Clinker is mixed with gypsum and ground to a fine powder to make cement.
Coal is used as an energy source in cement production. Large amounts of energy are required to produce cement. It takes about 200 kg of coal to produce one tonne of cement and about 300-400 kg of cement is needed to produce one cubic meter of concrete (World Business Council for Sustainable Development, 2002).
Coal combustion products (CCPs), such as Fly Ash also play an important role in cement manufacture and in the construction industry generally.