Uses of limestone

Limestone, quicklime and slaked lime are all used to neutralise excess acidity - which may be caused by acid rain - in lakes and in soils.

Limestone is used as a building material, and to purify iron in blast furnaces. It's also used in the manufacture of glass, and of cement (one of the components of concrete).

The main uses of limestone and its products

• Limestone (CaCO₃) can be used as a building material and in the manufacturing of iron.
• Glass - heated with sand and soda (sodium carbonate).
• Cement - heated with clay in a kiln.
  • Concrete - mixed with sand, water and crushed rock
  • Mortar - mixed with sand and water
• Quicklime - heated.
  • Slaked lime (Calcium Hydroxide Ca(OH)₂) - mixed with water
    • Lime motar - mixed with water

Glass

Glass is made by melting sand and then cooling it. Flat sheets of glass for windows are made by floating molten glass on a layer of molten tin.

Glass manufacturers add sodium carbonate to sand during the manufacturing process, to reduce the melting temperature of the sand and so save energy. The sodium carbonate decomposes in the heat to form sodium oxide and carbon dioxide, but this makes the glass soluble in water. Calcium carbonate (limestone) is therefore also added, to stop the glass dissolving in water. The calcium carbonate decomposes in the heat to form calcium oxide and carbon dioxide. About 90 per cent of glass is soda-lime glass, or bottle glass.