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. Granulometry was determined for the Víznar clay and mining sludge, while bulk density was measured for the fired bricks. The raw materials were analyzed by XRF and XRD, whereas the ceramic samples were characterized by water absorption, porosimetry, ultrasound pulse velocity, compressive strength testing, ESEM, leaching and colorimetry, to assess their chemical, physical and mechanical behaviour. 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 colour development, confirming their technical performance and suggesting their potential suitability from an environmental perspective. Their microstructure and stability depend on sludge content and firing temperature, essential factors for sustainable construction and architectural rehabilitation.
Duran-Suarez et al. (Fri,) studied this question.
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