The Uses of Calcium Oxide

Calcium oxide (CaO), commonly known as burnt lime, lime or quicklime, is a widely used chemical compound. It is a white, caustic and alkaline crystalline solid. As a commercial product lime often also contains magnesium oxide, silicon oxide and smaller amounts of aluminium oxide and iron oxide.

Paint industry

Quicklime is widely used in the manufacture of cement paint. It is also used as a filler. Quicklime is also a required to produce precipitated calcium carbonate (PCC) which is used as a coating and filling agent in paper.

Mining and oil industry

Water detection pastes contain a mix of calcium oxide and phenolphthalein. Should this paste come into contact with water in a fuel storage tank, the CaO reacts with the water to form calcium hydroxide. Calcium hydroxide is highly alkaline and will turn phenolphthalein into a vivid purplish-pink colour, thus indicating the presence of water.

Paper Industry

Calcium oxide is used to regenerate sodium hydroxide from sodium carbonate in the chemical recovery at Kraft pulp mills.

Other application

Calcium oxide is used in the construction industry to make cement and mortar for building purposes. It is added in asphalt for building roads to extend its lifespan and improve cohesion. It is also used to produce other chemicals for other purposes, such as calcium carbide.It is used to manufacture steel and iron from ores, as quicklime combines with the silica in the ore to form slag that can be removed from the pure molten iron or steel. It is also used in water treatment as well as reduction of air pollution. In glassmaking, calcium oxide is heated with silica and sodium carbonate to produce glass. 

Safety Information

Calcium Oxide Health & Safety Information

Signal WordN/A
Hazard StatementsH315-H318-H335
Hazard CodesC
Precautionary StatementsP261-P280-P305 + P351 + P338
Flash PointNot applicable
Risk Codes34
Safety Statements26-36/37/39-45
RTECS NumberEW3100000
Transport InformationUN1910 – class – PG 8 – Calcium oxide
WGK Germany1
GHS Pictograms