The chemical composition of coal ash and the content of the critical elements Ga, Sc, and V in coal and ash are examined herein. In this study, lignite and bituminous coal from Polish deposits were used. The coals were subjected to ultimate and proximate analysis; the petrographic composition was determined based on maceral groups. The chemical composition of ash and the content of critical elements were determined using ICP-MS. The obtained results were correlated and Pearson’s linear correlation coefficient was determined. Based on the correlation analysis, the relationship between the chemical composition of ash and the proximate and ultimate analyses was demonstrated. The content of selected critical elements in the tested deposits was lower than the Clarke value in coal. However, in some deposits these contents are much higher in coal ashes. The higher levels of Ga, V, and Sc in the ash are associated with Al₂O₃. Therefore, it can be stated that ashes can be a potential source of some raw materials. The highest concentrations of critical elements in coal and ash were recorded in the Lublin Coal Basin. Supra-Clarke contents of Ga, V, and Sc were recorded in the Bogdanka coal mine.

Critical raw materials are economically and strategically important for industry both in the short and long term. However, their supply is at high risk due to limited domestic deposits and reliance on imports. As demand for these materials grows, alternative sources must be explored. This study investigates the recovery of critical raw materials from waste, focusing on incineration residues, industrial byproducts, and electronic waste. The research analyzes various waste streams, including municipal solid waste incineration bottom ash and fly ash, as well as electronic and industrial waste, to determine their potential as secondary sources of critical materials. Key elements targeted for recovery include rare earth elements (REEs), antimony, vanadium, cobalt, and other strategic metals. The study evaluates the effectiveness of hydrometallurgical, pyrometallurgical, bioleaching, and electrochemical techniques for their extraction. Findings indicate that bottom ash contains 1–3% ferrous metals and up to 0.4% non-ferrous metals, including rare earth elements, while fly ash has substantial quantities of heavy metals suitable for recovery. The study highlights that large-scale recovery of critical raw materials from waste could reduce reliance on primary sources, support the circular economy, and enhance supply chain resilience in the context of energy transition. By providing a comprehensive assessment of recovery technologies and their economic and environmental implications, this study underscores the importance of waste as a valuable resource for critical material supply. The findings contribute to policy discussions on sustainable resource management and the reduction of geopolitical risks associated with raw material dependency.

The coal was gasified in a fluidized bed reactor with CO₂ as a gasifying agent at 889–980 °C. The coal and gasification residue produced during gasification was burned at temperatures up to 900 °C. The petrographic analysis, gasification residues, and fly and bottom ash resulting from the combustion of coal and chars showed the efficiency of the gasification and combustion processes. The gasification residue primarily comprised inertoids and crassinetwork, which accounted for 60% of the sample. The analysis of the petrographic composition of fly ash revealed that the fly ash formed during the combustion of gasification residue had a higher mineral content. The fly ash from the combustion of gasification products contained significantly less unburned coal compared to that from coal. The samples of the bottom ash from coal combustion were composed of approximately 25% organic matter, most of which was chars. The bottom ash formed from the combustion of coal gasification products was composed mainly of mineral matter (95% or higher). The obtained results have significant implications in determining future waste management strategies.