Calcium oxide

Calcium oxide (CAS 1305-78-8), commonly known as quicklime and approved as food additive E529, is a high-reactivity alkaline material produced by calcining limestone at high temperatures. It functions as a pH regulator, desiccant, and reactive base across a broad range of industrial processes. In water and wastewater treatment, it is used to raise pH and precipitate heavy metals.

Steel and non-ferrous metal producers rely on it as a flux to remove impurities during smelting and refining operations. Pulp and paper mills use it in the kraft recovery cycle to regenerate sodium hydroxide. This makes it integral to chemical recovery loops. In construction, it is the primary input for producing hydrated lime used in mortars, soil stabilization, and asphalt modification for infrastructure.

The material is supplied as lumps, granules, or fine powder depending on downstream processing requirements. Standard commercial grades include technical grade and high-calcium grades defined by CaO content. Purity typically ranges from 90% to over 98% depending on the source. Food-grade material conforming to regulatory specifications is available for applications requiring strict compliance.