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Mineral & Geology

calcium%20carbonate[1]Properties & Production

Calcium carbonate occurs in nature in one of three crystalline mineral forms – calcite, aragonite or vaterite. Calcium carbonate forms a significant proportion of the Earth’s crust, and so commercially exploited deposits are found throughout the word.  Most calcium carbonate deposits are made up of the skeletal remains of billions of marine plants and animals that have sedimented to the bottom of a shallow sea after their death.  If the conditions are right, these sediments can build up over geological time to form thick layers.

Subsequent geological movements coupled with the drying of the oceans can leave chalk deposits, such as those found in Great Britain and Northern France. Chalk deposits tend to consist of friable rocks that may contain some soil and clay-based impurities and can be variable in color. If further compaction occurs as the result of continued sedimentation and geological processes, harder limestone deposits are formed. These tend to be whiter and purer deposits than chalk with impurities concentrated into the form of flints and other mineral phases. When limestone has been subjected to extremes of temperature and pressure – for example, as a result of volcanic activity – the limestone melts and recrystallizes as marble.  In some cases, this natural process yields pure marble of exceptional whiteness, such as the famous deposits at Carrara, Italy.

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1. Geological movements combined with the drying of oceans leaves chalk deposits. Clays and soil components are deposited with time, some may permeate into chalk. 2. Minor compaction by late sediments becoming harder with formation of flints. Some compaction occurs to give harder limestone. 3. Volcanic activity leads to melting and recrystallisation as marble.

Calcium carbonate deposits can be found in most countries, however, the quality of the deposits and processing can be variable. A profound understanding of the geology coupled with the right processing (crushing, milling, classification and surface modification) of the calcium carbonate is essential in attaining the correct product properties. Imerys combines high quality feed materials, state of the art processing techniques and in-depth market knowledge to generate a broad portfolio of ground calcium carbonate (GCC) products for a wide range of industrial applications, including those tailored for the construction, paper, paint, plastics, film, adhesives and rubber industries.

In addition to GCC, Imerys also produces a range of precipitated calcium carbonate materials (PCCs).  PCC is produced through a chemical reaction process that utilizes calcium oxide (quicklime), water, and carbon dioxide. The reaction produces very pure calcium carbonate crystals that can be tailored to a variety of different shapes and sizes, depending on the specific reaction conditions used.  Imerys produces a range of PCC products characterized by specific particle shape, particle size distribution, and optical properties. Our process control systems ensure a consistent, high quality product that meets our customers’ precise specifications.

Quick View – Calcite

Product Appearance: Granulate to fine white powder – odorless

Particle Shape: Blocky

Molecular Formula: CaCO3

Molar Mass (g.mol-1): ~100

Specific Gravity (g.cm-3): 2.72

Refractive Index: 1.59

Mohs Hardness: 3