Uses of montmorillonite
Montmorillonite is used in the oil drilling industry as a component of drilling mud, making the
mud slurry viscous, which helps in keeping the drill bit cool and removing drilled solids. It is
also used as a soil additive to hold soil water in drought-prone soils, used in the construction of
earthen dams and levees, and to prevent the leakage of fluids. It is also used as a component of
foundry sand and as a desiccant to remove moisture from air and gases.
Montmorillonite clays have been extensively used in catalytic processes. Cracking catalysts have
used montmorillonite clays for over 60 years. Other acid-based catalysts use acid-treated
montmorillonite clays.
Similar to many other clays, montmorillonite swells with the addition of water. Montmorillonites
expand considerably more than other clays due to water penetrating the interlayer molecular
spaces and concomitant adsorption. The amount of expansion is due largely to the type of
exchangeable cation contained in the sample. The presence of sodium as the predominant
exchangeable cation can result in the clay swelling to several times its original volume. Hence,
sodium montmorillonite has come to be used as the major constituent in nonexplosive agents for
splitting rock in natural stone quarries in an effort to limit the amount of waste, or for the
demolition of concrete structures where the use of explosive charges is unacceptable.
This swelling property makes montmorillonite-containing bentonite useful also as an annular
seal or plug for water wells and as a protective liner for landfills. Other uses include as an
anticaking agent in animal feed, in paper making to minimize deposit formation, and as a
retention and drainage aid component. Montmorillonite has also been used in cosmetics.
In a fine powder form, it can also be used as a flocculant in ponds. Tossed on the surface as it
drops into the water, making the water "clouded", it attracts minute particles in the water and
then settles to the bottom, cleaning the water. Koi and goldfish (carp) then actually feed on the
"clump" which can aid in the digestion of the fish. It is sold in pond supply shops.
Sodium montmorillonite is also used as the base of some cat litter products, due to its adsorbent
and clumping properties
