What is pure calcium carbonate?

02-06-2025

1. Definition and Chemical Composition

Pure calcium carbonate (CaCO₃) is an inorganic chemical compound composed of calcium (Ca²⁺) ions and carbonate (CO₃²⁻) ions in a 1:1 molar ratio. It is one of the most abundant natural minerals on Earth and serves as a fundamental building block in geological, biological, and industrial processes.

  • Chemical Formula: CaCO₃

  • Molecular Weight: 100.09 g/mol

  • Crystal Structures: alcite (trigonal,moststable,form),Aragonite(orthorhombic, metastable),Vaterite (rare, hexagonal)


2. Physical and Chemical Properties

Pure calcium carbonate exhibits several key characteristics that determine its applications:


Description

AppearanceFine white powder
Density2.71 g/cm³ (calcite), 2.93 g/cm³ (aragonite) 
Melting Point Decomposes at ~840°C (forms CaO + CO₂)  
SolubilityNearly insoluble in water (0.0014 g/100 mL at 25°C), but dissolves in acids (e.g., HCl) with effervescence (CO₂ release)
PH (in water)9-10 (weakly alkaline)
Refractive Index1.49 (calcite), 1.53 (aragonite


3. Industrial and Commercial Uses

Pure calcium carbonate is widely utilized across multiple industries due to its:

  • Low cost

  • Non-toxicity

  • Alkalinity

  • High brightness & opacity

  • Industry


Applications

PharmaceuticalsAntacids (Tums), calcium supplements
Food & BeverageAdditive (E170), dough conditioner, acidity regulator
ConstructionCement, mortar, limestone aggregates 
Paper & PulpFiller & coating to improve brightness
Plastics & RubberReinforcing agent, improves stiffness
AgricultureSoil PH adjuster (lime substitute)
EnvironmentalFlue gas desulfurization (removes SO₂)
CosmeticsBulking agent in toothpaste, face powders


4. Differences Between Pure and Commercial Grades

Pure calcium carbonate (Lab/Pharma Grade):

≥99% purity, minimal impurities (e.g., Mg, Fe, Sr).

Used in sensitive applications (medicine, food).

Industrial/GCC Grade:

90-98% purity, may contain silica, clay, or metal traces.

Cheaper, used in construction, paints, and plastics.


5. Safety and Handling

Non-toxic (GRAS status by FDA).

Dust inhalation risk (may irritate lungs in powder form).

Incompatible with strong acids (releases CO₂ gas).


6. Analytical Testing Methods

To verify purity, techniques include:

X-ray Diffraction (XRD) – Identifies crystal structure.

Thermogravimetric Analysis (TGA) – Measures decomposition temperature.

Titration – Quantifies Ca²⁺ content via EDTA complexation.


Pure calcium carbonate is a versatile compound with critical roles in nature and industry. Its unique properties—alkalinity, low solubility, and abundance—make it indispensable in healthcare, manufacturing, and environmental management. Understanding its forms, production methods, and applications helps optimize its use across different sectors.

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