BENTONITE AND ITS IMPACT ON MODERN LIFE
Don D. Eisenhour and Richard K. Brown
The use of bentonite dates back at least 3000 years to ancient Greece where it was mined on the island of Kimolos and distributed throughout the Mediterranean (Aristophanes 405 bc). This white Kimolian bentonite was prized for its ability to clean wool and was used as a component of soap. From the time of Aristophanes to about 1900 the uses for bentonite remained limited (Robertson 1986).
However, after 1900 the applications for bentonite grew significantly. The use of bentonite in drilling fluids and in making green sand molds for metal casting began in the early 1900s. In the 1950s, the development of iron ore pelletizing created an additional high-volume market for bentonite. And, in the 1980s sodium-bentonite-based clumping cat litters were developed. All of these applications continue to grow and account for more than 70% of world wide bentonite consumption today (Eisenhour and Brown 2009).
Hundreds of other applications are responsible for the remaining 30% of consumption; almost all of these have been developed in the past century. In environmental applications bentonite is used in the treatment of waste waters, for sealing bore holes and well casings, and in the manufacture of geosynthetic clay lines which are used in landfills and reclaimed mines. Acid-activated bentonites are used to clarify edible oils, as coatings on carbonless copy paper, and as catalysts in the manufacture of petroleum products. Sodium bentonites are widely used to clarify wines in the USA, Europe, and Australia. Both sodium and calcium bentonites are used in animal feeds to absorb mycotoxins. When treated with cationic surfactants, organo-bentonites are formed which are used in paints, inks, greases, cosmetics, and oil-based drilling fluids.
More recently, organo-bentonites have been developed for use in polymers to increase strength, lower permeability, and improve weather resistance. Highly-purified sodium bentonites are used in a variety of cosmetics and pharmaceuticals as suspending agents and emulsion stabilizers, and in computer chip manufacturing in specialized polishing compounds. The rapid growth in the number and sophistication of bentonite applications has led to a corresponding growth and specialization in bentonite mining, testing, and processing methods.
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