Incorporação de rejeitos siderúrgicos e do pó de granito como matéria-prima na produção de cerâmica em olarias

Abstract

This study investigates the incorporation of industrial residues—steel mill sludge and granite powder—as alternative raw materials in the production of structural ceramics, evaluating their effects on the physical, thermal, and mechanical properties of the samples. Compositions with varying clay contents (85% and 75%), granite contents (15% and 25%) and water levels (10% and 15%) were prepared and sintered at 1100 ºC and 1200 ºC. The analyses included dimensional measurements, moisture behavior, flexural strength testing, and X-ray diffraction (XRD). Results demonstrated that moderate granite content (≈15%) combined with sintering at 1200 ºC promotes densification and improves mechanical strength, particularly in samples B3 and B4. Conversely, higher granite proportions resulted in reduced performance, indicating an optimal incorporation threshold. Samples from groups B and E exhibited catastrophic failure during sintering due to trapped moisture and vapor expansion, intensified by partial reduction of iron oxides. XRD confirmed the formation of densifying crystalline phases such as anorthite and spinel, which contribute to enhanced strength. Additionally, the study identified the lack of standardized procedures for specimen fabrication in the ceramic industry, highlighting the need for national guidelines to improve the comparability of mechanical test results. The findings confirm that residue incorporation is technically feasible and environmentally beneficial, provided that composition and processing parameters are strictly controlled.