Valorization of Tungsten Mining Waste and Clay Residues in the Production of Technical Ceramic Materials for Sustainable Construction and Architectural Rehabilitation

Mining and industrial activities generate large volumes of waste, up to 99% of the extracted material, forming a major global residue source. In this context, the valorization of mining sludge for sustainable construction materials gains relevance. This study examines the fabrication of ceramic bricks incorporating mining sludge from the Panasqueira mine, evaluating sludge incorporation levels and sintering temperatures to optimize resource use and reduce environmental impacts. Bricks were produced by blending residual clays from Víznar (Granada, Spain) with Panasqueira sludge at substitution rates of 10, 25 and 50%, and fired at 800, 950 and 1100 °C. The samples were characterized by XRF, XRD, water absorption tests, porosimetry, ultrasound pulse velocity, compressive strength testing, ESEM, leaching analysis and colorimetry to assess their chemical, physical and mechanical behavior. Both clays and sludge are rich in SiO₂ and Al₂O₃, suitable for ceramic processing, while fluxing oxides promote vitrification and densification. Incorporating 25 and 50% sludge reduces porosity, increases ultrasonic velocity and improves mechanical strength, achieving optimal performance at 1100 °C. Moreover, firing immobilizes toxic metals and allows controlled color development, confirming the technical and environmental suitability of these bricks, whose microstructure and stability depend on sludge content and firing temperature, essential factors for sustainable construction and architectural rehabilitation.