Ground Calcium Carbonates

Ground Calcium Carbonate (GCC) is produced by the mechanical grinding and classification of high-purity limestone or marble deposits to controlled particle size distributions. It is one of the most widely consumed industrial mineral fillers globally, valued for its high brightness, chemical inertness, low oil absorption, and cost-effectiveness across a broad range of applications.

Production involves primary crushing of quarried limestone, followed by secondary and tertiary grinding using ball mills, roller mills, or impact classifiers, and air classification to achieve the required particle size distribution. Key quality parameters are particle size distribution, brightness (ISO reflectance), calcium carbonate purity, and moisture content. Coated grades, in which the particle surface is treated with stearic acid or other fatty acids, are produced for polymer applications where improved dispersion and compatibility with non-polar matrices are required.

GCC differs from Precipitated Calcium Carbonate (PCC) in its production route. GCC is made by mechanical size reduction of natural limestone, whilst PCC is produced by chemical precipitation, allowing tighter control of particle morphology and size. GCC is generally less expensive and preferred in high-volume applications; PCC is used where specific particle shapes or ultra-fine sizes are required.

The chemical inertness of calcium carbonate across a wide pH range makes GCC compatible with most organic binder systems, including alkyd, acrylic, vinyl, and epoxy resins. Its refractive index of 1.59 means it does not contribute significantly to opacity, but it extends the pigment volume concentration of paint formulations and contributes to matting, texture, and film build.

Ground Calcium Carbonate is used as a primary filler and extender across a wide range of industrial sectors. In paints and architectural coatings, it is used at high loading levels to extend titanium dioxide, contribute to film build, and modify the rheological properties of the wet paint. Coarser grades provide a textured surface finish in masonry paints and exterior renders; fine grades contribute to smooth, high-sheen finishes in interior emulsions. In the plastics industry, GCC is used in PVC compounds, polyolefins, and thermoset resins, where it improves stiffness, dimensional stability, and surface quality. Coated grades with stearic acid surface treatment are preferred in polymer applications to improve dispersion and prevent agglomeration. In the paper and board industry, GCC is used as a coating pigment and filler to improve brightness, opacity, and printability. In adhesives, sealants, and caulks, it provides body, reduces shrinkage, and improves the mechanical properties of the cured product.