Potential Use of Sandy Mining Wastes as Raw Material in Road Construction

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TECHNICAL NOTE

Potential Use of Sandy Mining Wastes as Raw Material in Road Construction Maria del Pilar Durante Ingunza . Olavo Francisco dos Santos Ju´nior Andre´ Tabosa Fernandes de Santa Cruz Gerab

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Received: 14 May 2019 / Accepted: 21 May 2020 Ó Springer Nature Switzerland AG 2020

Abstract Sustainable programs are increasingly stimulating the use of industrial wastes, minimizing economic and environmental impacts. This use is especially notable in the mining industry, in which the amount of discarded material is exaggeratedly higher than the amount of obtained product. In this context, the aim of this paper is to study the sandy wastes generated from beneficiation processes of scheelite (CaWO4) to determine its potential use as a raw material in pavements. First, a physical, chemical and mineralogical characterization of the sandy wastes was performed. Subsequently, geotechnical characterization tests (grain size analysis, specific gravity, compaction, CBR and direct shear) were performed. The waste presented a heterogeneous mineralogical composition which is consistent with the mineralogical composition of the scheelite host rocks. The main minerals are calcite, quartz, micas and silicates of the garnet group and the pyroxene group that commonly occur in calcium-rich metamorphosed sediments. This resulted in a sandy and non-plastic material, positively M. del Pilar Durante Ingunza (&)  O. F. dos Santos Ju´nior Department of Civil Engineering, Federal University of Rio Grande do Norte (UFRN), Natal, Brazil e-mail: [email protected] A. T. F. de Santa Cruz Gerab Postgraduate Program in Civil Engineering, Federal University of Rio Grande do Norte (UFRN), Natal, Brazil

influencing the geotechnical behaviour. The results show that the residual strength envelope exhibits zero cohesion for compaction energies, but the residual friction angle increases with the increasing energy. The values obtained for the strength parameters indicate that this material can be used as road embankment layers. Keywords Sandy wastes  Scheelite  Raw material  Road construction 1 Introduction Scheelite (CaWO4) is a calcium tungstate mineral (Mohs hardness of 4–5) commonly found in granitic pegmatites, metamorphic contact deposits and hightemperature lodes associated with granitic rocks (DANA 1978). It is exploited to obtain tungsten, a strategic element that has a broad range of applications, especially in the electrical, military and space industries. In Brazil, the skarn deposits located in Borborema Province in the northeast are the most important sources of tungsten. As tungsten is considered a strategic element due to its large range of uses, the deposits have attracted strong interest in the economic development programmes of the region. In the context of sustainability and environmental conservation, one of the greatest challenges facing the world population is the proper management of solid waste, particularly mining waste.

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