What is limestone?
Limestone is composed of sedimentary rock. It is partially soluble in water and weak acid solutions. Depending on how it formed, the natural state of limestone can be crystalline, granular or massive. It is composed mostly of calcite and aragonite, which are crystal forms of calcium carbonate. Most limestone comes from skeletal fragments of prehistoric marine life, such as coral, and often contains varying amounts of clay
, sand, silica or silt.
Limestone is used in a wide variety of applications including as a building material, a primary ingredient in cement, as aggregate in road construction and as a feedstock for chemical reactions.
About 10% of the total volume of all sedimentary rock on earth is limestone.
How is limestone used?
Limestone is commonly used in architecture. This use was most popular in the late 19th and early 20th centuries, especially for building train stations, banks and government buildings.
Some of the worlds’ most famous buildings are constructed using limestone, including:
- The Empire State Building (USA)
- The Pentagon (USA)
- The Palace of Westminster (UK)
- The London Bridge(UK)
- The Colosseum (Italy)
Limestone also has many other uses. Making cement is the largest of these, accounting for about 25% of global limestone consumption. Cement is most commonly used as a construction material, especially as the setting component in concrete.
Lime manufacturing accounts for a further 10%. Lime has many uses in agriculture, chemical manufacturing, construction, food processing, steelmaking and water treatment.
Other uses of limestone include as an additive in tooth pastes, paints, paper and plastics. Crushed limestone is used as a soil conditioner, or as an aggregate in the construction of road base. Limestone can also be used in glassmaking, or to filter out sulphur dioxide from potential emission sources.
Who uses limestone?
Accurate global production and consumption statistics for limestone are not readily available. However, it is well known that cement production and lime manufacturing are currently the biggest single uses of limestone. The cement industry is the largest limestone consuming industry, estimated to consume as much as 25% of global limestone production, with lime production accounting for a further 10%.
China is the worlds’ largest producer in both of these major limestone consuming industries. In 2010 China produced 1,800 million tonnes of ceme nt, 54% of the global total. India produced 220 million tonnes of cement to become the second biggest producer. The third biggest cement producer was the USA at 68 million tonnes in the same year.
In 2009, China’s lime manufacturing industry produced 185,000 tonnes of lime. This is more than 10 times the production of the USA. The USA is the second biggest producer, accounting for 15,800 tonnes of lime in the same year. They were followed closely by India, who accounted for 13,000 tonnes. China is also a world leader in other major limestone consuming industries such as agriculture, road construction and steelmaking.
Limestone consumption plays a key part in the functioning of all modern societies, through its wide variety of medical, agricultural and industrial applications.
Where does limestone come from?
Limestone is found in abundance across the globe. Estimates suggest that close to 100 million tonnes of limestone are mined globally each year, most of which are consumed domestically. In 2008 China was the worlds’ biggest producer, accounting for over 60% of the estimated total global production. India, the USA and Europe are also considered major limestone producers.
Most countries around the globe produce significant amounts of limestone for domestic consumption.
Interesting facts about limestone:
- The outside cover of the Great Pyramid of Giza is made entirely of limestone.
- Kingston, Canada is nicknamed the ‘Limestone City’ because so many buildings there are constructed from limestone.
- Limestone can be used to make weather and heat resistant roofing for homes.
- Many modern buildings use thin sheets of limestone on exterior walls, to give the impression of a building constructed from limestone
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