EARTH

[3812-23-06] Beneficiation of low grade Korean bentonite for industral applications

○Wantae Kim¹, Sungki Chae², Hyunsoo Kim¹, Sangbae Kim¹ (1. Korea Institute of Geoscience and Mineral Resources, 2. University of Science and Technology)

Chairman:Richard Alorro (Curtin University)

Keywords:Bentonite, Montmorillonite, Separation, Swelling, Opal-CT

Bentonite is a clay deposit most commonly generated from the alteration of volcanic ash, consisting predominantly of smectite minerals, usually montmorillonite. Depending on the nature of its genesis, bentonite contains a variety of accessory minerals, which may include mainly quartz, feldspar, opal cristobalite/trydimite (opal-CT), calcite, illite and mica. The presence of these accessory minerals can impact the industrial value of the deposit, reducing its commercial value depending on its applications. Therefore, bentonite is often purified by removing these impurity minerals for special applications where specific properties and characteristics are required. Among the special applications, bentonite is often used in the cosmetic and pharmaceutical industry as both excipient and active ingredient in the forms of liquid (suspensions, emulsions), semi-solid (creams, ointments) and solid (powder, capsules and tablets). The basic requirements for bentonite to be used as raw material are pure, microbiological and mineralogical inertness. Physical properties such as swelling volume and gel formation are also important. Particularly, microcrystalline silica polymorphs such as quartz, cristobalite and opal-CT should be controlled and removed as far as possible because they show sufficient evidence of carcinogenicity in humans. In this work, the removal of opal-CT from bentonite was attempted. A calcium type bentonite (Ca-bentonite) containing microcrystalline opal-CT was subject to a series of test in order to develop an effective separation process and identify the technological futures of the separation products. The process variables that influence the separation have been examined.