The paper presents the characteristics of products annealing at the temperatures of 2400 and 3000 °C of unburned carbon from coal fly ash in terms of its possible use as a starting material in the graphitization process. An amorphous substance (organic substance) with an admixture of some minerals has been found in samples subjected to graphitization. However, the graphite phase is dominant in products subjected to graphitization. Studies have also shown a diverse grain morphology in individual samples. The presence of plate-shaped and tube-shaped grains was found. As the graphitization temperature of the starting material increases (2400 and 3000 °C), the specific surface area in the graphitization products decreases. The total pore volume in the samples after the graphitization process was significantly lower than the pore volume of active carbons produced from other unburned carbon. Average pore diameter is similar to the pore diameter in active carbons. The reflectance value of the matrix for the sample graphitized at 3000 °C is characteristic for graphite. Unburned carbon from Polish fly ash can be used as the starting material for graphitization.

The purpose of this paper is to examine the possibility of reduction of free calcium oxide content in waste from fluidized bed boilers by treating them with carbon dioxide under various conditions. The primary examination concerning the possibilities of reducing the content of free calcium oxide in waste included carbonation process in a laboratory, taking into account various parameters of the process. The primary examination has been carried out in a fluidized bed reactor, rotary reactor and a ball mill reactor.Depending on the reaction process, the variables in the examined processes included: reaction time, temperature, amount of the catalyst (water), application of an abrasive material. After completion of the process, the treated material was tested with regard to the content of free calcium oxide. Thus, it was possible to determine the most optimal conditions for treatment of combustion products from fluidized bed boilers, that is the conditions which will ensure reduction of the content of free calcium oxide at an appropriate level, under the physical conditions most similar to normal conditions and in the shortest possible time

The economic development of EU countries is limited due to limited access to a number of mineral raw materials, which necessitates actions aimed at securing the supply of CRM. For this reason, CRMs constitute elements of particular importance for the EU. The aim of the study was to assess the content of CRMs as a potential source of REY in fly ash resulting from the coal combustion in one of the power plants in the Czech Republic. In the tested ash the main phases are: glassy phase, mullite and quartz. The chemical composition of the tested fly ashes showed dominance of SiO2 and Al2O3. The CRM included Co, Sb, W, Be, Nb, Ga, lanthanides and Y, as well as Cr and In. Light elements have the largest share among REE, while heavy elements have the smallest share. In the tested fly ash, the share of critical elements, the content of uncritical elements and the content of excessive elements in the total REY content were also determined. Based on the analyzed results, the value of the Coutl prospective coefficient was calculated, which assesses the profitability of obtaining CRM from fly ash as an alternative source of these metals.

This study presents the development and evaluation of a technology for producing geopolymer-based granulates, which act as sustainable substitutes for natural aggregates by utilizing waste materials. The technology is demonstrated to be energy-efficient compared to other manufactured aggregate processes (such as sintering), as it relies on a cold-bonding process and achieves self-hardening at room temperature. The granulation of geopolymer materials using an intensive counter-current mixer represents an innovative solution in the field of producing substitutes for natural aggregates. Coal fly ash (CFA) was used as the primary aluminosilicate precursor, with composite regrind from decommissioned wind turbine blades (CR) and steelmaking dust (SD) tested as additives. Reactive solids and alkaline activator liquids were mixed and granulated in a single operation using an intensive counter-current mixer; moistening and surface powdering were applied to improve granule sphericity. The granules were cold-cured at room temperature and characterized after 28 days by grain size distribution, crushing resistance, water absorption, abrasion (micro-Deval), SEM/EDS and leaching tests. The results indicate that the additives significantly improved the mechanical performance: PM + PK granules reached crushing strengths > 6 MPa, while CFA + SD granules reached > 11 MPa, exceeding many commercial lightweight aggregates (such as LECA or Lytag), as detailed in the paper. The CFA + CR granulates exhibited a compact microstructure and the effective immobilization of several heavy metals, whereas the CFA + DS samples demonstrated the excessive leaching of Cr, Pb and Mo. The process achieved a high solid-to-liquid ratio (>2.0), reducing activator consumption. Composite regrind is recommended as a promising additive.

This article presents the possibilities of using modern measuring devices to determine the properties of process residues (Polish acronym: UPP). UPP was taken from the combustion process from a power plant in Silesia. Determining the properties of UPP is the basis for making decisions about its practical application, for example, as a raw material to obtain useful products such as: pozzolan, cenosphere or zeolite, for which there is demand. The development of advanced technology and science has given rise to modern and precise research tools that contribute to the development of appropriate methods to assess the properties of post-process residue. For this study the following were used: scanning electron microscope with EDS microanalysis and an analyzer for particle size-, shape- and number- analysis. The study conducted confirms the effectiveness of SEM analysis to determine the properties of post-process residue from Clean Coal Technologies (CCT). The results obtained are an introduction to further research on the determination of properties of CCT post-process residue. Research to determine the properties of CCT post-process residue only began relatively recently