Calcium hydroxide is an inorganic compound with the formula Ca(OH)2. It is a colorless crystal or white powder. It is also known as hydrated lime or slaked lime. In India, Pakistan and Afghanistan, it is also known as Choona. It has a boiling point of more than 1000 ◦C, and it dissolves sparingly in water to give a highly alkaline solution of pH 12 to 13. The calcium hydroxide mineral portlandite is relatively rare and is found in some volcanic, plutonic, and metamorphic rocks, and in burning coal dumps.
The limestone is quarried and processed, and limestone contains calcium carbonate undergoes thermal decomposition at high temperatures to form calcium oxide or burnt lime. Calcium oxide is treated or slaked with water to produce calcium hydroxide on a commercial scale: CaO + H2O → Ca(OH)2. The calcium oxide is broken down into fine particles of calcium hydroxide in this hydration reaction and this occurs in a continuous hydrator. The particle sizes can be modified through milling to ensure consistent particle size.
Calcium hydroxide is utilized for producing beverages like alcohol and soft drinks. And it’s also applied in preparation a traditional Swedish food called Lutefisk. The food storage and shipping industries are also used calcium hydroxide. It prevents fruits to ripen before it’s shipped to grocery store. Calcium hydroxide is also applied as a food additive, as a preservative in canned pickles.