What is Lime?

Origin & Properties

Lime is calcium oxide ($\text{CaO}$) with an atomic weight of 56. It is a pozzolanic compound which, when combined with water, silica, and aluminum (such as ordinary clay), forms a cementitious material with suitable strength for road beds, grades, and subgrades. As an indispensable chemical ingredient, it serves hundreds of specialized manufacturing applications globally.

Manufacture of Lime

Calcium oxide is derived from limestone found in high-purity deposits. Limestone ($\text{CaCO}_3$) is mined in large chunks and ground down to approximately 4 to 5 inches in diameter. This ground stone is then fed into high-efficiency kilns operating at approximately 2100°F (1150°C) for nearly 4 hours.

During this calcination process, carbon dioxide gas is driven off. The hot exhaust gases are returned to the kiln pre-heater to maintain thermal efficiency. After the firing cycle, limestone is completely converted into calcium oxide ($\text{CaO}$), losing nearly half of its original weight as released carbon dioxide.

Lime Processing & Forms

The quicklime exiting the kiln is cooled and crushed into pebbles approximately ¾ inches in size. This pebble lime can be distributed directly or converted into Hydrated Lime ($\text{Ca(OH)}_2$) by adding precise quantities of water to form a dry powder containing less than 2% free moisture. Additionally, pebble lime and hydrated lime can be processed with excess water to create Lime Slurry, eliminating dust hazards during mass transfer.

Core Applications

• Steelmaking: Serves as a flux agent to remove silica and phosphorus impurities from molten steel.
• Environmental Engineering: Neutralizes industrial acid effluent and purifies municipal drinking water.
• Agriculture: Adjusts soil pH levels to optimize fertilizer uptake and agricultural yields.
• Civil Infrastructure: Binds reactive soils for subgrade stabilization in roadbed construction.