Potential Application of Bauxite and Iron Mining Residues in Civil Construction in Brazil

Abstract

Alumina is generated from the processing of an ore known as bauxite; the process generates a highly alkaline red-colored waste containing iron, titanium, and silica that can change any material’s properties that comes into contact with the waste. According to Abal (Aluminio Associação Brasileira de Aluminio: Perfil da indústria Brasileira do. São Paulo 2019 [1]), Brazil is the third-largest producer of alumina in the world and the fourth-largest bauxite producer. On the other hand, iron is one of the most abundant natural elements being obtained from minerals such as hematite, magnetite, limonite, and siderite. Brazil is the second-largest producer of iron ore globally, mainly in the region known as the Quadrilatero Ferrífero QF in the Minas Gerais State. The storage and disposal of waste from iron and aluminum production has become a major environmental problem. South America is a region rich in mineral resources, so the number of tailings dams is very high and, in most cases, built without respecting international standards and good engineering practice. Exploring mineral resources and destroying the native forest, contaminating water resources, and throwing gases and particulate matter into the atmosphere also consume much energy and contribute to global warming. The main methods of disposal of mineral products in Brazil are the cheapest wet path and have a much higher potential for environmental impact than the dry path. In recent years in Brazil, there have been significant tragedies involving tailings dams of iron, such as the failure of the Fundão dam on November 5, 2015, and the Brumadinho dam’s failure on January 25, 2019. Both cases caused the deaths of approximately 270 people and 25 missings. Thus, better mechanisms should be evaluated for the disposal of mining tailings such as dry processing and to reduce the use of dams in Brazil and South America. This work aimed to investigate the potential uses of alumina and iron tailings in civil construction. The waste has reasonable characteristics to be used as embankment fill material in infrastructure works, foundation material of some engineering works, ground improvement, or calcined additives in cement manufacturing and flexible pavements.