Definition - What does Lime mean?
Lime is a calcium-containing inorganic material in which carbonates, oxides and hydroxides predominate. In fact, lime is calcium oxide or calcium hydroxide. Hydrated lime is calcium hydroxide, Ca(OH)2, the cement in concrete. Lime is used extensively for wastewater treatment with ferrous sulfate and productions of cement.
Lime is used in large quantities as:
- Building and engineering materials
- Chemical feed stocks
- Production of chemicals
- Sugar refining
Lime industries and the use of many of the resulting products date from prehistoric periods all over the world.
Corrosionpedia explains Lime
Lime is commonly calcium oxide, CaO. It is a white crystalline solid with a melting point of 4662°F (2572°C). It is manufactured by heating limestone, coral, sea shells, or chalk, which are mainly composed of CaCO3, to drive off carbon dioxide.
Lime has an adhesive property with bricks and stones, so it is used as a binding material in masonry works. It is also used in whitewashing as wall coat so that the white wash adheres to the wall.
Lime used in building products is broadly classified as:
- Pure - Also known as fat, rich, air, slaked, slack, pickling, hydrated, and high-calcium lime. It consists primarily of calcium hydroxide and may contain up to 5% of other ingredients
- Hydraulic - Also called water lime. It contains lime with silica and/or alumina and sets with exposure to water, and can set underwater.
- Poor lime - Also known as lean or meager lime. Poor lime sets and cures very slowly and has weak bonding
Nearly 45% of lime is used in the steel industry. Lime is also used in the production of other metals. For example, it is used to remove silicates from alumina before the alumina is reduced to aluminum metal.
Lime is used in stack gas scrubbers to reduce sulfur dioxide emissions from power plants. It is also added to sewage to remove phosphates. The pretreatment of water supplies involves the use lime to decrease the acidity, to soften and to clear drinking water. A variety of other industrial processes also make extensive use of lime.