Calcium Carbonate – an exceptional mineral
Calcium carbonate is composed of three elements which are of particular importance for all organic and inorganic material on our planet: carbon, oxygen and calcium. Calcium carbonate (CaCO3) is a white solid, is non-toxic and odourless.
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The earths crust contains more then 4% calcium carbonate, making it one of nature’s most abundant raw materials. Calcium carbonate is found as rock in all parts of the world, is the main component of seashells and is usually the principal cause of hard water. As well being dissolved in rivers and oceans, the mineral can be found in molten form as “cold” carbonatite-lava, or as a solid in the form of stalactites, stalagmites or as the major constituent of whole mountain ranges.
Calcium carbonate geology
Calcium carbonate is normally found as a white mineral (calcite) which occurs naturally in chalks, limestones and marbles. Some of these rocks were formed by inorganic processes, but many are of organic origin being composed of the remains of countless sea organisms. Most are limestones, a general term used for a rock possessing varying proportions of calcite and dolomite with small amounts of iron-bearing carbonates. Dolomite is a double carbonate of calcium and magnesium, with the formula CaMg(CO3)2. Limestones are usually clear or white. However, with impurities, they can take on a variety of colours, commonly white, tan or grey.
The most common crystal arrangement for naturally-occurring calcium carbonates is the hexagonal form of calcite. Less common is aragonite, which has a discrete or clustered needle, orthorhombic crystal structure. Aragonite is formed in a narrow range of physio-chemical conditions, typically in thermal springs although mollusc shells and pearls are made of aragonite.
Calcium carbonate production
Commercial calcium carbonate is produced in 2 ways: through the extraction and processing of natural ores or synthetically through chemical precipitation. Ground calcium carbonate is commonly referred to as GCC. Precipitated Calcium Carbonate (PCC) is produced through a recarbonisation process or as a by-product of some bulk chemical processes (e.g. the Solvay method or caustic soda production).
A long history of uses from prehistory to the present day
Calcium carbonate has been used since prehistoric times to the present day. The history of calcium carbonate shows how we have been able to utilise the unique properties of this mineral to improve the quality of life through the ages.
Today, Calcium carbonate powders, precipitated products and dolomite, are among the most important and versatile materials used by industry. It is used as a filler and functional additive in an incredible variety of industrial applications ranging adhesives & sealants, building products, glass, paints & inks, paper, plastic & rubber to animal feeds, flue-gas desulphurisation, fertilizers, food, personal care, pharmaceuticals and water treatment.