What is calcium nitrate?

Calcium nitrate is a compound also known as Norwegian saltpetre. It is a salt that draws moisture from the air and is used in fertiliser but also has other uses including:

Waste water treatment

Calcium nitrate’s use in waste water is in 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 sulphates stops, thus preventing formation of hydrogen sulphide – which means there is no odour.

Fertiliser and pesticide

As of 1978, only 170,000 tonnes per year were produced for applications in fertilisers. The fertiliser grade is popular in the greenhouse and hydroponics trades; it contains ammonium nitrate and water, as the “double salt”

Calcium nitrate is also used to control certain plant diseases. For example, dilute calcium nitrate (and calcium chloride) sprays are used to control bitter pit and cork spot in apple trees.

Latex coagulant

Calcium nitrate is a used in latex production, especially in dipping processes. Dissolved calcium nitrate is a part of the dipping bath solution. The warm former is dipped into the coagulation liquid and a thin film of the dipping liquid remains on the former.

Concrete

Calcium nitrate is used to quicken the setting of concrete mixtures. 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 plasticisers.

Cold packs

The dissolution of calcium nitrate tetrahydrate is highly cooling. For this reason, calcium nitrate tetrahydrate is sometimes used for regenerable cold packs.

Molten salts for heat transfer and storage

Calcium nitrate can be used as a part of molten salt mixtures. Typical are binary mixtures of calcium nitrate and potassium nitrate or ternary mixtures including also sodium nitrate. Those molten salts can be used to replace thermo oil in concentrated solar power plants for the heat transfer, but mostly those are used in heat storage.