Study by DTA/TG of the formation of calcium aluminate obtained from an aluminium hazardous waste

Abstract

A Spanish hazardous waste from tertiary aluminium industry was used as a raw material for the synthesis of calcium aluminate. An amorphous precursor was obtained by a hydrothermal method at different values of pH. The transformation of the precursor in a crystalline aluminate was followed by TG/DTA up to 1300 ºC. At temperatures between 719 and 744 ºC, the precursors evolve towards the formation of C12A7 which becomes CA at circa 1016 ºC. Mass spectrometry coupled to thermal analyser allowed the identification of the decomposition products.