Novel Inorganic Products Based on Industrial Wastes

Abstract

This contribution reports the use of industrial wastes, red mud and tionite, obtained upon refining and extraction of bauxite and titania ores, respectively. For red mud, two applications were explored: geopolymers and clinker/cement. According to this study, only after 14 days the effects of addition of red mud are translated into technological properties of geopolymers. Moreover, in small proportions the mechanical strength was improved at 28 days curing, certainly due to the high alkaline nature of the waste. Belitic clinkers with balanced amounts of cementitious phases were produced at 1,350 °C. Mortars cured for 10 days produced from those clinkers/cements show mechanical strength that tends to increase when high amounts of C3S are formed. The relative content of C2S is also important in the hardening process. With the addition of red mud, the technological properties of the mortars were enhanced due to the pozzolanic reactivity of this sludge. The tionite was selected to be recycled as ceramic pigment. The colorimetric parameters of tionite pigment calcined at 1,200 °C and its application in transparent glaze show a light brownish colour, due to the strong brightness (L*). This colour should be exalted by the intercalation of metal ions present in the sludge that could form a metal bearing rutile phase. In the glaze, the yellow component (+b*) doubled and responds for the final beige coloration .