Reactions of ammonium sulphates with kaolinite and other silicate and oxide minerals

Abstract

AbstractInteractions of ammonium sulphates and various silicate and oxide minerals have been studied by X-ray heating methods and simultaneous TG-DTA. Kaolinite and other clay minerals were found to be very susceptible to these sulphating treatments, (NH4)3Al(SO4)3, (NH4)Al(SO4)2 and Al2(SO4)3 being formed successively with increasing temperature from 350 to ∼550°C. The same reaction products were obtained on heating mixtures of (NH4)2SO4 and γ-Al2O3, Al(OH)3 and bauxite. Fe-, Mg- and Ti-silicates and oxides gave NH4-double sulphates below 400°C and the corresponding metal sulphates above this temperature.