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The production of building materials is unavoidable if the well-being and development of society are to be maintained. However, in manufacturing these materials, significant greenhouse gas emissions and environmental effects are produced. For this reason, and with the aim of reducing the impact of the manufacture of these materials, this work developed a geopolymeric material made up solely of wastes, brick dust and biomass bottom ashes which replaced the traditional ceramic materials. To evaluate the quality of this sustainable geopolymeric material, different groups of specimens were formed with different percentages of both residues, subsequently determining the physical properties of the new-formed geopolymers and guaranteeing they accomplish the prescriptions of the ceramic regulations for construction. In addition, the results of the geopolymer characterisation tests were statistically analysed using factor analysis, with the sole purpose of establishing connections and interdependence between the variables that influence the geopolymerisation process. Thus, it was possible to demonstrate that the combination of brick dust and biomass bottom ashes produced geopolymers with adequate qualities to replace traditional ceramics, as well as that the different combinations of both residues produced feasible materials to be used as ceramics with various characteristics, with two main factors determined by factorial analysis that governed the physical properties of the geopolymer obtained: the percentage of brick dust and the theoretical porosity. [ABSTRACT FROM AUTHOR]

Soils contaminated by mining activities are a major environmental concern, and to avoid this type of environmental impact, carrying out high-cost processes is necessary. For this reason, a solution is proposed in this study in order to eliminate the soils contaminated by mining activities and, in turn, prevent the soil's contaminating elements from causing harm. All this is achieved by using contaminated soils as raw materials for the production of ceramics for bricks. For this purpose, the materials were initially characterized physically and chemically, and different ceramic test pieces were manufactured with different percentages of clay and contaminated soil, subsequently determining the physical properties and the leaching of toxic elements. In this way, it was possible to evaluate, via innovative data mining and fuzzy logic techniques, the influence of the contaminated soil's contribution on the properties of ceramics. Based on this, it was possible to affirm that the contaminated soil incorporation negatively affects the physical properties of ceramics as well as the leaching of polluting elements. The ceramic formed by contaminated soil and clay has a lower compressive strength, and it is associated with lower linear shrinkage and lower density, as well as higher porosity and cold-water absorption. However, the addition of different percentages of contaminated soil (up to 70%) to clay created a ceramic that complied with regulation restrictions. Therefore, it was possible to obtain a sustainable material that eliminates environmental problems at a lower cost and that fits within the new circular mining concept thanks to fuzzy logic techniques. [ABSTRACT FROM AUTHOR]

Steel is one of the most widely used materials in the past and today. Various techniques are used to recycle this material, including the electric arc furnace. This process has several advantages, but it also has a major disadvantage, namely, the generation of waste such as electric arc furnace dusts. Electric arc furnace dusts are classified as hazardous waste due to their high percentage of heavy metals, including zinc. Consequently, in the present research, the leaching of zinc for recovery with sulfuric acid solutions at ambient temperature and atmospheric pressure is evaluated, as well as the reuse of the leaching process residue as a raw material for ceramic materials. The sulfuric acid solutions were 0.125, 0.25, 0.5, and 1 molar, using clay for ceramic conforming and percentages of the leaching residue from 0–50%. The results showed that the optimum solution was 1 molar sulfuric acid, recovering all the zinc in the sample in 36 h. Furthermore, it was found that the clay-conformed ceramics with less than 40% leaching residue showed acceptable physical and mechanical properties according to standards. Therefore, this research develops a new environmental hydrometallurgy in which metallic elements of interest are valorized and the production of waste is avoided, reducing the deposition of hazardous waste in landfills and the extraction of raw materials for the manufacture of construction materials. [ABSTRACT FROM AUTHOR]