Bentonite

The term Bentonite refers to a rock, precisely to a clay, generally made up of minerals from the smectite group and in particular from montmorillonite. Sodium montmorillonite smectites are the most valuable and can contain up to 90 % of useful minerals. The most important deposits derive from argillification processes of volcanic precursors deposited in a marine or lake environment.

The main component is montmorillonite which other clay minerals (illite, kaolinite, etc) are associated with as well as residual minerals such as: quartz, feldspar, calcite, biotite, opal, cristobalite and also zeolites. The presence or absence of these components explains the great variety of extracted bentonite, whose remarkable diversity can influence the quality of the mineral and therefore industrial applications.

The first bentonite deposit was discovered around 1890 in Wyoming, Montana, near Fort Benton, the place that gave its name. The United States is the world’s leading producer, followed by China, Turkey, Greece and India. The main Italian deposits are in Sardinia and Puglia. Extraction is usually done in open-cast quarries.

THE PROPERTIES OF BENTONITE DEPEND ON THE RICHNESS OF CLAY PHASES AND THE HIGH EXCHANGE CAPACITY:

Viscosity

Binding Agent

Gelling agent

Water absorbent

Italiana Zeoliti sells grey and white bentonite which, due to their peculiar characteristics, have as main applications:

• Animal care. The introduction of clumping cat litters in our houses is closely tied to bentonite. In fact, sodium bentonite is able to adsorb large quantities of water by swelling. Furthermore, the clumping and binding properties favor the use of bentonite in litters. This avoids cat owners to throw away the entire litter whenever it gets dirty, as they can simply discard every single lump from the litter. Thus, lives of cats are more sanitary and those of their owners are simpler and cheaper.
• Agriculture. With its absorbent features, bentonite reduces the growth of fungi, cryptogams and insects that need a moist environment to thrive. For this reason, it is sprayed in an aqueous suspension on the leaves of crops such as vines and strawberries and used to improve the performance of fertilizers.
• Civil and environmental engineering. There are many applications in engineering: sludge for oil and geognostic drilling, geosynthetic bentonite barriers used in hydraulic operations, transport infrastructures and waterproofing of underground structures.