Precipitated calcium carbonate (PCC) is an innovative product derived from lime, which has many industrial applications.  PCC is made by hydrating high-calcium quicklime and then reacting the resulting slurry, or “milk-of-lime”, with carbon dioxide.  The resulting product is extremely white and typically has a uniform narrow particle size distribution.  PCC is available in numerous crystal morphologies and sizes, which can be tailored to optimize performance in a specific application.

Characteristic

The different shapes allow Precipitated calcium carbonate to act as a functional additive in sealants, adhesives, plastics, rubber, inks, paper, pharmaceuticals, nutritional supplements and many other demanding applications. A formulator can choose a shape, and the physical properties that result from that shape, that gives the best performance in the end use.

In the PCC process, products can be made with very small sizes, with high surface areas, high oil absorptions, and/or with different powder bulk densities— from ultra-low  to super-high powder densities.

Applications

Calcium carbonates, including PCC, are considered to be non-toxic. In the U.S., the Food and Drug Administration has Affirmed calcium carbonate to be GRAS (Generally Recognized As Safe). As long as the PCC meets certain purity requirements, it can be used as a direct food additive, as a pharmaceutical or as an indirect additive in paper products that come in contact with food. 

Preparation

The vast majority of calcium carbonate used in industry is extracted by mining or quarrying. Pure calcium carbonate (such as for food or pharmaceutical use), can be produced from a pure quarried source (usually marble).

Alternatively, calcium carbonate is prepared from calcium oxide. Water is added to give calcium hydroxide then carbon dioxide is passed through this solution to precipitate the desired calcium carbonate, referred to in the industry as precipitated calcium carbonate (PCC):

CaO + H2O → Ca(OH)2

Ca(OH)2 + CO2 → CaCO3↓ + H2O