Industrial applications
Used in swimming pools as a pH corrector for
maintaining alkalinity "buffer" to offset the acidic
properties of the disinfectant agent.
The main use of calcium carbonate is in the
construction industry, either as a building material in
its own right (e.g. marble) or limestone aggregate for
road building or as an ingredient of cement or as the
starting material for the preparation of builder's lime
by burning in a kiln. Calcium carbonate is also used in
the purification of iron from iron ore in a blast
furnace. Calcium carbonate is calcined in situ to give
calcium oxide, which forms a slag with various
impurities present, and separates from the purified
iron.
Calcium carbonate is also used in the oil industry
in drilling fluids as a formation bridging and
filtercake sealing agent and may also be used as a
weighting material to increase the density of drilling
fluids to control downhole pressures. Calcium carbonate
is also one of the main sources used in growing Seacrete,
or Biorock. Calcium carbonate is widely used as an
extender in paints,[3] in particular matte emulsion
paint where typically 30% by weight of the paint is
either chalk or marble. Calcium carbonate is also widely
used as a filler in plastics.[3] Some typical examples
include around 15 to 20% loading of chalk in uPVC drain
pipe, 5 to 15% loading of stearate coated chalk or
marble in uPVC window profile. PVC cables can use
calcium carbonate at loadings of up to 70 phr (parts per
hundred parts of resin) to improve mechanical properties
(tensile strength and elongation) and electrical
properties (volume resistivity). Polypropylene compounds
are often filled with calcium carbonate to increase
rigidity, a requirement that becomes important at high
use temperatures.[4] It also routinely used as a filler
in thermosetting resins (Sheet and Bulk moulding
compounds)[4] and has also been mixed with ABS, and
other ingredients, to form some types of compression
molded "clay" Poker chips.
Fine ground calcium carbonate is an essential ingredient
in the microporous film used in babies' diapers and some
building films as the pores are nucleated around the
calcium carbonate particles during the manufacture of
the film by biaxial stretching. Calcium carbonate is
also used in a wide range of trade and DIY adhesives,
sealants, and decorating fillers. Ceramic tile adhesives
typically contain 70 to 80% limestone. Decorating crack
fillers contain similar levels of marble or dolomite. It
is also mixed with putty in setting stained glass
windows, and as a resist to prevent glass from sticking
to kiln shelves when firing glazes and paints at high
temperature. Calcium carbonate is known as whiting in
ceramics/glazing applications, where it is used as a
common ingredient for many glazes in its white powdered
form. When a glaze containing this material is fired in
a kiln, the whiting acts as a flux material in the
glaze. In North America, calcium carbonate has begun to
replace kaolin in the production of glossy paper. Europe
has been practicing this as alkaline papermaking or
acid-free papermaking for some decades. Carbonates are
available in forms: ground calcium carbonate (GCC) or
precipitated calcium carbonate (PCC). The latter has a
very fine and controlled particle size, on the order of
2 micrometres in diameter, useful in coatings for paper.
It is commonly called chalk as it has been a major
component of blackboard chalk. Chalk may consist of
either calcium carbonate or gypsum, hydrated calcium
sulfate CaSO4·2H2O.
Health and
dietary applications
Calcium carbonate is
widely used medicinally as an inexpensive dietary
calcium supplement or antacid.[5] It may be used as a
phosphate binder for the treatment of hyperphosphatemia
(primarily in patients with chronic renal failure). It
is also used in the pharmaceutical industry as an inert
filler for tablets and other pharmaceuticals.[6] Calcium
carbonate is also used in homeopathy as one of the
constitutional remedies.
Ecological applications
Currently calcium carbonate is used to neutralize
acidic conditions in both soil and water.
