“A rare and naturally-ocurring silicate for a wide range of rheological, adsorption and bindering applications due to its unique three-dimensional structure and needle-shapped particle form.”
Attapulgite clays (also known as Palygorskite) are crystalline hydrated magnesium aluminium silicates with a unique chain structure that gives its unusual colloidal and sorptive properties. Its slurries are viscous and highly thixotropic and, unlike bentonite clays, attapulgite clays are not flocculated by electrolytes (so they are less sensitive to salts).
Attapulgite/Palygorskite deposits are relatively rare in comparison with the other industrial clays. Major deposits occur in USA, Senegal and China.
Attapulgite consist of double silica tetrahedral chains linked together by octahedral oxygen and hydroxyl groups containing Al and Mg ions in a chain-like inverted structure. The inverted tetrahedral occurs regularly and causes channels through the structure. Attapulgite contains two types of water— one coordinated to the octahedral cations and other loosely bonded in the channels. The latter water is referred to as zeolitic water. The channels may also contain exchangeable cations. The elongated morphology and the presence of the channels are the most important physical attributes.
The principal applications of attapulgite rheological grades generally involve thickening, gelling and stabilizing which improves basically syneresis control and anti-sagging effect.
Attapulgite clays are used on a wide variety of industrial applications, specially the rheological (colloidal) ones:
- PAINTS & COATINGS: syneresis control and better thixotropy, sag resistance (in combination with cellulose derivatives)
- SUSPENSION FERTILIZERS: stabilization and suspension properties (not affected by electrolytes in the media)
- BUILDING MATERIALS: thixotropic effect, better sag resistance, improved workability
- DRILLING MUDS: viscosifiers additives in saline mud systems (not affected by salt)
- MOLECULAR SIEVES: bindering effect
- OTHER: attapulgite clays can be used at ceramic glazes, pigment slurries, chemical products…
For further info about RHEOPLUS attapulgite clays: www.rheoplus.com
SOURCES:
- USDA – https://www.ams.usda.gov/
- ATTAPULGITE: ITS PROPERTIES AND APPLICATIONS, W. Lynwood Haden and I. Albert Schwint, 1967
