An overview of the coal circularity in Brazil: A new sustainable approach based on sampling method, characterization, and waste valorization

Coal is a key energy source globally, and Brazil holds substantial reserves. However, approximately 50% of the coal extracted in Brazil is discarded as waste, often mixed into a single material without selective characterization. This study aims to establish a framework to help mining companies identify and implement strategies for sustainable coal mining practices in the study region. Residual fraction samples were collected and analyzed for their characteristics and potential applications. The results showed that the clay content in the waste is influenced by the age and depth of the coal deposits, while the beneficiation process determines the pyritic content. Based on these findings, four groups of residual fractions were identified for specific applications. Group 1, with higher carbon content, is suitable for processing and carbon concentration. Group 2, characterized by low pyrite content, coarse granulometry, and neutral pH, may be used to concentrate clay minerals for ceramics and mortars. Group 3, rich in clay minerals, is suitable for fertilizers, techno-soils, pozzolans, and geopolymers. Group 4 includes samples with potential for pyrite concentration. This study highlights the value of systematic waste sampling and evaluation, providing an effective strategy to promote the circular economy. This approach supports sustainable development in the research region and beyond by unlocking the potential of coal mining waste.