What are the industrial uses of calcium oxide
Calcium oxide, as a basic inorganic chemical, is mainly produced through high-temperature calcination of limestone in industrial production. This process is carried out in a lime kiln at 950 ° C to 1200 ° C, where calcium carbonate undergoes a decomposition reaction, producing calcium oxide and releasing carbon dioxide. Controlling the calcination temperature and time is the key to obtaining products with high activity and low sulfur content. Its strong alkalinity, ability to react with acids, high hydration, and ability to react with acidic oxides under certain conditions to form silicates and aluminates form the core chemical basis for its wide application in many industrial fields.
Calcium oxide is an indispensable flux in the metallurgical industry, especially in the steel manufacturing process. In the blast furnace ironmaking process, it is heavily invested, and its main function is to react with the gangue components (mainly silicon dioxide) in iron ore and the ash content in fuel to generate calcium silicate slag with a lower melting point. This process effectively reduces the melting temperature of the slag, allowing it to smoothly separate from the molten iron and float upwards, thereby achieving purification of pig iron. More importantly, it forms stable calcium sulfide through strong binding with sulfur elements, significantly reducing the sulfur content in molten iron, which is crucial for improving the mechanical properties such as toughness and ductility of the final steel. During the steelmaking stage, calcium oxide continues to play a role in slagging, desulfurization, and dephosphorization, and is one of the core auxiliary materials to ensure the quality of steel.
The field of environmental governance is an important direction for the application of calcium oxide. In flue gas desulfurization systems, it is widely used as an efficient and economical desulfurizer. Its working principle is that the slurry of calcium oxide or its hydrate calcium hydroxide comes into full contact with flue gas containing sulfur dioxide, undergoes acid-base neutralization reaction, generates calcium sulfite or further oxidizes to calcium sulfate. This chemical process can effectively remove over 90% of sulfur dioxide in flue gas, meeting strict environmental emission standards. Similarly, in industrial wastewater treatment, by utilizing its alkalinity, it can efficiently neutralize acidic wastewater and form insoluble hydroxide precipitates of heavy metal ions, achieving the removal of heavy metals and purification of wastewater.
The chemical industry and the construction industry both heavily rely on calcium oxide. It is the basic raw material for producing various calcium salts, such as preparing precipitated calcium carbonate through carbonization method, or used for manufacturing bleaching powder, etc. In the early stages of the "Solvay method" soda ash manufacturing process, calcium oxide recovered ammonia through causticization reaction, which is a classic manifestation of circular economy in chemical production. In the construction industry, calcium oxide reacts with water to produce calcium hydroxide (matured), which then reacts with carbon dioxide in the air to regenerate calcium carbonate and harden. This characteristic makes it the main cementitious material for traditional building mortar. Although Portland cement dominates in modern concrete, calcium oxide remains an essential key component in cement production, providing the necessary calcium oxide components in cement raw materials.
In addition, in the chemical pulping process of the paper industry, calcium oxide is an important component in the preparation of cooking liquids, used for alkali recovery and lignin treatment. In agriculture, it is used as a soil amendment to improve crop growth environment by increasing the pH value of acidic soil. Its strong alkalinity also endows it with the ability of sterilization and disinfection, which is often used in the disinfection and sterilization of farms and the harmless treatment of sick and dead animals.
From high-temperature melting metallurgical furnaces to purification devices for environmental pollution control, from vast chemical production systems to basic construction projects, calcium oxide, with its unique chemical properties, has demonstrated extensive and critical application value. Although its production process appears ancient, its application technology continues to deepen with the development of various industrial fields, continuously consolidating its important position as a modern industrial basic raw material.
