A relatively rare mineral, calcium hydroxide arises naturally from rocks or burning coal dumps. It has become a common manufactured chemical, produced for a diverse number of important industrial and commercial purposes. In general, avoid contact because calcium hydroxide is a potent poison that can cause tissue damage in living organisms.
Features
Calcium hydroxide is composed chemically of one calcium atom bonded to two hydroxides. A hydroxide, as its name implies, is a molecule of oxygen and hydrogen atoms bonded together. Calcium hydroxide manifests itself as a dry colorless powder, and it is also known as hydrated lime. Lime is a general term applied to a group of calcium-filled inorganic compounds in which carbonates, oxides or hydroxides dominate. The sedimentary rock known as limestone is closely related.
Formation
According to Peters Chemical Company, a leading supplier of chemical lime, commercial calcium hydroxide is produced by treating quicklime, also known as calcium oxide, with sufficient amounts of water to satisfy its chemical affinity for the liquid. Water adds its two hydrogen atoms and one oxygen atom to the formula. This chemically converts the simple oxygen atom, known as the oxide, to two hydroxides--the combination of hydrogen and oxygen.
Types
The exact composition of calcium hydroxide will vary depending upon the type of quicklime and the hydrating conditions used. High-calcium hydrated lime is made from high-calcium quicklime. It contains about 75 percent calcium oxide and 25 percent water. Dolomite hydrated lime, a type of carbonate rock and mineral, is made when the calcium oxide fraction of dolomite quicklime hydrate. It is about 50 percent calcium oxide, 33 percent magnesium oxide and 15 to 17 percent water. Dolomite hydrated lime may also be made under pressure, which reduces the amount of calcium oxide but expands the amount of water.
Uses
Calcium hydroxide is used for water treatment to remove impurities, sewage treatment to maintain proper pH, treatment of industrial waste to abate pollution, solid waste disposal, ceramic production, food production, metallurgy and pulp and paper production. It is also used to make building material, pigments, water paint, leather, rubber, bleaches, dyes, varnish, petrochemicals and petroleum.
Health Effects
Calcium hydroxide is intended to be an ascetic inorganic substance, and like many chemicals, it reacts badly with organic tissue. Symptoms that result from contact with calcium hydroxide depend upon the effected tissue. For example, calcium hydroxide will burn or irritate the skin, and if it reaches sensitive areas, such as the eyes, ears and throat, loss of vision and severe pain can result. Medline Plus states that poisoning will occur when calcium hydroxide is swallowed. Vomiting, internal bleeding and abdominal pain are common symptoms of poisoning. If inhaled, calcium hydroxide can make breathing difficult. Dissemination of the chemical from the lungs to the blood can lower blood pressure and change the acidity of the blood.
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