Improved Quantification of Gibbsite in Bauxite Ores by Thermogravimetric Methods (TGA and DTG)

Abstract

The major source of alumina is from bauxite ores. Bauxite ores are not pure clay mineral species but are composed of a mixture of mineral components. The components and amounts vary with location. The main aluminous components found in bauxite ores are gibbsite (Al(OH)3), boehmite (γ-AlO(OH)) and diaspore (α-AlO(OH)). These may occur individually or as mixtures of these components. This study offers an improved approach to the quantification of the gibbsite component in naturally occurring bauxite ores using the thermal method of analysis known as either Thermogravimetry (TG) or Thermogravimetric Analysis (TGA). The methodology used in this study involves the use of an experimentally determined empirical gravimetric factor, G, rather than the theoretical factor based on the stoichiometric equation for the complete dehydroxylation of gibbsite.