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The Effect of Calcium Carbonate Particle Size and Shape on the Properties and Performance of Calcium Carbonate Granulations

Calcium carbonate is used as an active ingredient in dietary supplements and antacids, as well as an excipient in prescription and OTC (over-the-counter) drugs. Calcium carbonate has inherently poor compressibility. As a result, it is commonly combined with organic binders such as maltodextrin, starch, or acacia gum to attain adequate compressibility for inclusion in tablets. A calcium carbonate granulation is the controlled agglomeration of calcium carbonate with these binders.

Wet Granulation Study of Precipitated and Ground Calcium Carbonates
The Specialty Minerals Inc. (SMI) Consumer Products Laboratory studied the effect of calcium carbonate particle size, particle size distribution, and particle shape on the processing behavior and tableting performance of calcium carbonate granulations with maltodextrin. Using a high-shear wet granulation process, SMI tested precipitated calcium carbonates (PCCs) having four different shapes and ranging in particle size from 0.8 to 12 microns, as well as a ground calcium carbonate (GCC), 3.5 microns in size.

The study concluded that:

  • The granulation process and granulation physical properties are most affected by calcium carbonate particle size and particle size distribution.
  • Calcium carbonate morphology has the greatest impact on granulation tableting properties and tablet performance.
  • PCC provides granulations with greater porosity.
  • PCC imparts faster disintegration than GCC, as well as superior dissolution at the 10 percent binder concentration commonly used in commercial granulations.
  • Lower-bulk density, higher-surface area PCCs (scalenohedrals) produce the most porous and smooth textured granulations.
  • Granulation properties and performance of granulations made with scalenohedral PCCs can be improved with the addition of a higher density rhombohedral-shaped particle.
  • The rapid disintegration achieved with PCC would be advantageous for effervescent and quick-dissolve tablets.
  • Smooth granulation texture achieved with smaller-size PCC, even at low binder levels, is advantageous for tablet applications where palatability or mouth feel is important.  Suggested applications are chewable and quick-dissolve tablets.
  • PCC, with its different particle morphologies and broad choice in particle sizes, provides the greatest flexibility in creating granulations with specific, targeted tableting performance properties.

Specialty Minerals Precipitated Calcium Carbonates for Granulations

  • Rhombohedral: ViCALity® Heavy, CalEssence® 450 and ViCALity® Ultra Heavy PCCs.  These are 3.0, 4.5 and 12.0 microns in size. The ViCALity® PCC grades have low levels of lead, less than 500 ppb (parts per billion), while the CalEssence® PCC grades have ultra-low levels of lead, less than 125 ppb. Each of these families have products that are 3.0, 4.5 and 12.0 microns. The ViCALity® PCC equivalent to CalEssence® 450 PCC is ViCALity® Extra Heavy PCC. The CalEssence® PCC equivalent to ViCALity® Heavy PCC is CalEssence® 300 PCC, and to ViCALity® Ultra Heavy PCC is CalEssence® 1500 PCC. Larger-sized SMI PCC particles are also produced in Europe under the Sturcal™ PCC trademark.
  • Scalenohedral: ViCALity® Extra Light PCC has an open structure formed from calcite needles, with high surface area and high oil absorption. The CalEssence® PCC family equivalent is CalEssence® 160 PCC. This type of product is also made by SMI in Europe: Calopake® Extra Light PCC.
  • Smaller-sized PCC: ViCALity Albafil® PCC, a 0.7 micron prismatic particle, and ViCALity Albaglos® PCC, an 0.8 micron product that is ViCALity Albafil® PCChas 15 percent of ViCALity® Heavy PCC added to improve powder flow and water slurry viscosity. Both can be used in tableting. The CalEssence® PCC family equivalents are CalEssence® 70 PCC and CalEssence® 80 PCC.

The ViCALity® and CalEssence® PCCs are manufactured in SMI’s plant in Adams, Massachusetts, and the Calopake® PCC is manufactured in SMI’s plant in Birmingham, U.K. All meet the local Pharmacopeia and food additive requirements and are certified Kosher.

Additional information on the use of these PCCs in nutritional supplement, antacid, and pharmaceutical applications can be found by clicking on one of these links:


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