Bentonite is essentially a highly plastic clay . Bentonite is valued in foundry sand binding, drilling .
Bentonite is the active protective layer of geosynthetic clay liners. Drilling: Another conventional use of bentonite is as a mud constituent for oil and water well drilling. Its roles are mainly to seal the borehole walls, to remove drill cuttings and to lubricate the cutting head.
There is limited information on occupational exposure to bentonite dust in mines fibrotic reaction to montmorillonite in the absence of free silica.