Influence of different Al2O3-containing batch materials on melting, fining and properties of soda-lime-silica glass

Abstract

Proceeding from the composition (in wt% ) : 72.5 SiO2, 1.5 AI2O3, 10.5 CaO, 2.5 MgO, 12.5 Na2O, and 0.5 K2O the batch raw materials calcined and hydrated alumina, nepheline syenite, Calumite, and Ecomelt, respectively, were employed in order to introduce aluminum oxide to the glass. Batch calculations assured constant chemical composition, sand/sulfate ratios, sulfate/carbon ratios, redox numbers, and total sulfur contents. The glasses and melts obtained were investigated with respect to different properties, e. g. viscosity, homogeneity, optical transmission, and residual sulfur content. The results display similarities, however, partly also significant differences with respect to the AI2O3 source used. Thus especially the glasses containing the blast furnace slags revealed distinct characteristics compared to glasses with nepheline syenite and hydrated alumina. With increasing melting time the differences are reduced.