Limestone is a naturally abundant sedimentary rock composed largely of calcium carbonate (CaCO₃) or dolomite (calcium magnesium carbonate). Through a process called calcination, heating to around 900 °C, limestone loses carbon dioxide and transforms into calcium oxide (CaO), commonly known as quicklime. Following this, quicklime can react with water to form calcium hydroxide (Ca(OH)₂), or hydrated lime.
Quicklime (CaO) is a white or greyish‑white solid with a density of around 3.34 g/cm³. It reacts vigorously with water, converting into hydrated lime. Its performance and purity depend significantly on the original limestone composition, for example, a high‑calcium lime may contain over 97 % CaO with low magnesium oxide (MgO) content, while a dolomitic variety may contain substantial MgO.
Industrially, lime is a critically important basic material. Quicklime finds application across multiple sectors: in steelmaking it acts as a flux and impurity‑remover; in paper and pulp it aids bleaching and purification; in water treatment it softens water and removes contaminants; in construction and civil engineering it stabilises clay‑rich soils; and in non‑ferrous metallurgy (including copper, gold, aluminium, lithium, nickel) it features in flow sheets. Hydrated lime serves other uses, for example in building construction and chemical manufacturing.
Firering Strategic Minerals plc (LON:FRG) is an emerging quicklime producer and critical minerals explorer, with operations in Zambia and West Africa.
