Calcium oxide is indispensable in multiple industrial sectors due to its versatility and cost-effectiveness. In the steel industry, it serves as a flux, helping to remove impurities like silica, phosphorus, and sulfur during smelting. In construction, quicklime is a key ingredient in cement and mortar production, enhancing strength and durability.

In the environmental sector, calcium oxide is used for water treatment, where it neutralizes acidic waters and removes heavy metals. It also plays a role in flue gas desulfurization, reducing sulfur dioxide emissions from power plants.

The chemical industry uses calcium oxide in the production of calcium carbide, which is essential for acetylene gas manufacturing. In the paper industry, it helps regenerate sodium hydroxide during the Kraft process.

Its desiccant properties make it useful for preserving and storing grains, preventing moisture-induced spoilage. With such a wide range of functions, calcium oxide continues to be a critical material across modern industry.