Speaker
Description
The transition toward a circular economy requires the transformation of industrial waste streams into valuable secondary raw materials, reducing dependence on primary resources while minimizing environmental impacts associated with waste disposal. Among industrial by-products, coal fly ash represents one of the most significant residues generated from thermal power production and has considerable potential for resource recovery and sustainable material production.
This study aims to evaluate the potential of Macedonian coal fly ash as a secondary raw material through quantitative assessment and comprehensive chemical characterization, with particular emphasis on its suitability for the recovery of valuable elements and its further application within circular economy strategies. The estimated volume of fly ash generated from the investigated thermal power plant reaches 106.8 ± 5.1 million m³, indicating a significant secondary resource base. Chemical characterization revealed that the investigated fly ash samples are predominantly silicate-based materials, containing approximately 50 wt.% SiO₂, 19–20 wt.% Al₂O₃, and 15–16 wt.% Fe₂O₃, together with other alkali and alkaline earth metal oxides.
The assessment of potentially valuable and critical elements demonstrated the presence of significant concentrations of selected metals, including manganese (1100–5038 mg kg⁻¹), arsenic (31–191 mg kg⁻¹), gallium (30–35 mg kg⁻¹), as well as rare earth elements such as cerium (147–153 mg kg⁻¹) and lanthanum (60–78.1 mg kg⁻¹). These findings indicate that coal fly ash may represent a promising alternative source of valuable elements and contribute to the diversification of critical raw material supply chains. Furthermore, after the selective extraction of rare earth elements and other valuable metals, the remaining aluminosilicate-rich fraction retains significant potential for the synthesis of geopolymer materials, enabling a sequential valorization pathway and maximizing resource utilization.
These findings provide relevant information for researchers, industrial stakeholders, and potential investors interested in developing sustainable recovery and utilization technologies.