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NITRATES > Calcium Nitrate

Calcium nitrate, also called Norgessalpeter, is the inorganic compound with the formula Ca(NO3)2. This colourless salt absorbs moisture from the air and is commonly found as a tetrahydrate.

Formula: Ca(NO3)2, Molar mass: 164.088 g/mol, Melting point: 561 °C, Density: 2.50 g/cm³, Soluble in: Water

Use in fertilizer

As of 1978, only 170,000 tons/year were produced for applications in fertilizers. The fertilizer grade (15.5-0-0 + 19% Ca) is popular in the greenhouse and hydroponics trades; it contains ammonium nitrate and water, as the "double salt" 5Ca(NO3)2.NH4NO3.10H2O. Formulations lacking ammonia are also known: Ca(NO3)2.4H2O (11.9-0-0 + 16.9%Ca). A liquid formulation (9-0-0 + 11% Ca) is also offered. An anhydrous, air-stable derivative is the urea complex Ca(NO3)2.4[OC(NH2)2], which has been sold as Cal-Urea.

Waste water treatment

Calcium nitrate is used in waste water pre-conditioning for odour emission prevention. The waste water pre-conditioning is based on establishing an anoxic biology in the waste water system. In the presence of nitrate, the metabolism for sulfates stops, thus preventing formation of hydrogen sulphide. Additionally easy degradable organic matter is consumed, which otherwise can cause anaerobic conditions downstream as well as odour emissions itself. The concept is also applicable for surplus sludge treatment.


Calcium nitrate is used in set accelerating concrete admixtures. This use with concrete and mortar is based on two effects. The calcium ion accelerates formation of calcium hydroxide and thus precipitation and setting. This effect is used also in cold weather concreting agents as well as some combined plasticizers.[4] The nitrate ion leads to formation of iron hydroxide, whose protective layer reduces corrosion of the concrete reinforcement.

Cooling baths

The dissolution of calcium nitrate tetrahydrate is highly endothermic (cooling). For this reason, calcium nitrate tetrahydrate is sometimes used for regenerateable cold packs.

Heat storage

Calcium nitrate together with Potassium and Sodium nitrate is used to absorb and store energy in the Concentrated Solar Power plants. It can be used as a heat transfer fluid instead of the thermal oil.