Studies on the use potential of iron ore tailings as alternative raw material in manufacture of ceramic and hydraulic tiles.

Abstract

Iron ore mining is a very important economic activity to Brazil. The increase in tailings generation, as well as its inadequate waste disposal, has awakened concerns over the sustainability of its processes, mainly due to the environmental impacts and socioeconomic risks associated with tailing dams. On the other hand, the reuse of the tailings in building materials can contribute to the sustainable consumption of resources, mitigation of the negative environmental impacts, new market opportunities and the aggregation of values to the companies. This study aims assessment of the potential use of iron ore tailings as an alternative raw material in the production of ceramics and cement tiles. The materials were collected from four tailings-dams and an part was subjected to a dry separation procedure. Besides the iron ore, two other powder fractions were produced (“clay” and “sand” fractions). The clay, sand, and residual iron ore concentrate were characterized (particle size and morphology, chemical and mineralogical composition). The residual iron ore concentrate showed fine, crystalline, and dense particles, no toxic, suitable technically for use as addition and aggregate in the production of terracotta cement tiles. The sands showed the greatest uniformity (particle size and shape, mineralogy and chemical composition) which contributed to the compressive strength gains of the cement composites. The clay present adequate plasticity and dry strength, and develop mullite and glass upon firing. Despite the greatest firing shrinkage (between 22.59 and 26.51%), the resulting tiles show a appealing dark brown luster and are very compact (vitrified products, classified in groups BIa, BIb or BIIa), with high mechanical strength.