
USA Purification of bentonite Google Patents
Finely comminuted, crude bentonite may be purified of accompanying quartz, muscovite, illite, feldspar, iron oxide and like impurities by pouring an aqueous slurry of the clay into a very dilute aqueous solution of a technical grade of sodium hexametaphosphate, and letting the mixture stand a few minutes, whereby almost the entire mineral impurities present are precipitated.