Separation and Purification of Montmorillonite from Raw Bentonite Using a Simple Hydrothermal Treatment

Herein, a simple hydrothermal treatment method is proposed to separate high-purity montmorillonite from natural clay stone, bentonite, which contains various associated minerals. Specifically, a suspension of bentonite is placed in a closed vessel and heated to temperatures above approximately 100 °C. High-purity montmorillonite is collected by recovering the gel fabricated by heating. Evidently, the purity and collectability of montmorillonite is higher with higher temperatures and longer periods of treatment. High-purified montmorillonite aggregates and forms a gel in a dilute suspension of bentonite, after being heated at high temperatures over 110 °C, in a closed system. Using this property, we proposed a method for the separation of highly purified smectite from raw bentonite. The experimental result reveals that Ca-type smectite can be purified by the method.