Ceramization as an Alternative for Reducing Contaminant Mobility in Coal Mining-Impacted River Sediments

This study evaluates the characteristics and environmental behavior of river sediments impacted by coal mining in the southern coal region of Santa Catarina, Brazil. Sediments accumulated in mining-affected rivers represent an environmental liability due to the presence of potentially toxic elements and their limited management options. In this context, ceramization is investigated as an alternative strategy for reducing contaminant mobility through thermal treatment of sediments collected at four sampling points (PU1–PU4) along the Urussanga River. Initially, leaching and solubilization tests were performed to assess the mobility of chemical elements, and the raw sediments were further characterized by chemical, mineralogical, and thermal analyses. Subsequently, ceramic specimens were produced from the sediments and subjected to thermal treatment at 1100 °C. After firing, the specimens were re-evaluated through leaching and solubilization assays to verify changes in contaminant mobility after the ceramization process. The results showed that raw sediments exhibited aluminum, iron, and manganese concentrations in the solubilized extract that exceeded regulatory thresholds, particularly for iron, which reached up to 21.91 mg/L. After thermal treatment, a substantial reduction in the solubility of these elements was observed, with concentrations falling below the established limits at all sampling points. This reduction in mobility is likely associated with physicochemical transformations occurring during firing, including matrix densification and the incorporation of elements into less soluble phases, as reported in previous ceramic processing studies. Overall, the findings demonstrate that ceramization represents a promising strategy for reducing contaminant mobility in coal mining-impacted river sediments, offering a viable and environmentally friendly alternative for sediment management and valorization.