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.
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.
Precipitated calcium carbonate (PCC) is produced by precipitating a calcium salt out of a solution under defined conditions. Normally, a filtered solution of calcium hydroxide Ca(OH)2 (from burnt lime) is used as the calcium source. This must not contain any colored impurities. Calcium carbonate is precipitated by the admixture of gaseous carbon dioxide or sodium carbonate Na2CO3.
The form of calcium carbonate obtained – in other words, its particle shape and particle size distribution – depends on the precipitation conditions, such as concentration, temperature and temperature change during precipitation, agitation energy, pH and other factors.
When comparing to standard Ground Calcium Carbonates (GCC), Precipitated Calcium Carbonates (PCC) can be distinguished for:
In addition the great advantage of Precipitated Calcium Carbonate (PCC) related to GCC is the possibility of having different crystalline forms which yield to predetermined physical properties.
For example, the opacity and whiteness of Precipitated Calcium Carbonate (PCC) is important in some applications, while in some other cases the rheological behavior is the fundamental characteristic, consequently the different Precipitated Calcium Carbonate (PCC) grades are very distinct and the peculiarities of their use in each sector must be discussed in close collaboration with the customers.