Bentonite is used as a binder in foundry sands in molds production. Silica sand is the main component in foundry sand. It forms a structural framework of the mold due to bentonite as it binds sand particles which results in the mold strength.
The main advantage of bentonite is an ability to restore its properties after extra moistening. This makes it possible to use the foundry sand after pouring metal and knockout of casting several times. Multiple use of foundry sand with bentonite significantly reduces the expenses related to waste removal and their disposal.