Incorporation of sulphidic mining waste material in ceramic roof tiles and blocks

The demand for building and construction materials increases as the world population keeps growing, thus increasing the need of shelter, as a basic human need. This increasing demand for building and construction materials not only leads to higher demand for primary raw materials, such as clay or sand, but also to higher emissions of carbon dioxide that contribute to the greenhouse effect, leading us to the biggest and ongoing threat to life on earth: global warming. The potential use of secondary raw material sources, such as mining waste, in building and construction products not only minimises the ecological footprint of this sector but also minimises the pressure on the primary raw material sector, hence fostering the transition towards a more resource efficient and sustainable world. The goal of this study is to evaluate the potential use of uncleaned sulphidic mining tailing material from two inactive Pb-Zn (Plombières, Belgium) and Cu-Zn-Pb (Freiberg, Germany) mines, and uncleaned sulphidic mining waste rock material from an active Cu-Zn mine (Neves-Corvo, Portugal), in ceramic roof tiles and blocks taking into account production parameters (shaping, drying, and firing processes), product quality (technical, aesthetical, and chemical properties) and environmental compliance of secondary raw materials for use as building products. After a detailed physical, mineralogical, chemical, and thermal characterisation of the materials, blends for ceramic roof tiles and blocks were made by partly or totally replacing some primary raw materials (mainly clay and sand) by 4 different mining waste materials. Roof tile and block blends containing 5 wt% and 10 wt% mining waste materials, respectively, were produced on a lab scale. The required technical, aesthetical, and chemical properties for each ceramic product were evaluated. Freiberg tailing and Neves Corvo waste rock materials presented considerable amounts of sulphur and metal(loid)s. Moreover, technical, aesthetical, and chemical properties of the blends using these mining waste materials were not satisfying and the Neves Corvo waste rock materials have the disadvantage of needing a mechanical treatment (grinding and sieving) before integrating them into the ceramic blends. Therefore, the Freiberg tailing and both of the Neves Corvo waste rock materials are less suitable to replace primary raw materials in ceramic roof tile and block blends, even in smaller amounts (5 wt% and 10 wt%, respectively). In contrast, the Plombières fine tailing material was characterised by a low sulphur and metal(loid) content, as well as satisfying environmental performance. The roof tile and block blends, in which the Plombières tailing material was integrated, showed satisfying technical, aesthetical, and chemical properties. Consequently, the Plombières tailing material can be considered as the best fit to partly or totally replace primary raw materials in both ceramic roof tile and block blends.