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As a common byproduct of thermal power plants, coal fly ash (CFA) is often dumped in landfills, where it can cause environmental damage. As a result, in this work, porous construction bricks were made utilizing a byproduct of a thermal power plant, coal fly ash, and baking yeast to absorb carbon dioxide and dust. Yeast was utilized for pore formation, CFA detoxifying, and crack repair. The physical properties of prepared porous bricks are characterized using .X-ray diffraction (XRD), scanning electron microscopy (SEM), confocal microscopy (CM), and Fourier transform infrared spectroscopy (FTIR) According to the XRD analysis, the brick is made up of quartz, hematite, and mullite. The Porous Brick absorbed 36% of water and 2.5% of dust. The porous fly ash brick has demonstrated superior strength (17.5MPa) and load bearing capacity as compared to traditional bricks in compressive testing. For analysis of the fly ash bricks' ability to absorb carbon dioxide, a gas chromatograph equipped with a Flame Ionization Detector (FID) was utilized. A high adsorption capability of 94.69 percent of CO2 was found for the produced geopolymer bricks. The yeast involvement promote and facilitates the self-healing ability of the coal flay ash brick (CFB).

The concentration of critical elements, including such REE as Fe, Co, W, Zn, Cr, Ni, V, Mn, Ti, Ag, Ga, Ta, Sr, Li, and Cu, in the so-called fly ash obtained from the 9 Polish power plants and 1 thermal power station has been determined. The obtained values, compared with the global average concentration in bituminous coal ash and sedimentary rocks (Clarke values), have shown that the enrichment of fly ash in the specified elements takes place in only a few bituminous coal processing sites in Poland. The enrichment factor (EF) is only slightly higher (the same order of magnitude) than the Clarke values. The enrichment factor in relation to the Clarke value in the Earth’s crust reached values above 10 in all of the examined ashes for the following elements: Cr, Ni, V, W, and, in some ash samples, also Cu and Zn. The obtained values are low, only slightly higher than the global average concentrations in sedimentary rocks and bituminous coal ashes. The ferromagnetic grains (microspheres) found in bituminous coal fly ashes seem to be the most economically prospective in recovery of selected critical elements. The microanalysis has shown that iron cenospheres and plerospheres in fly ash contain, in addition to enamel and iron oxides (magnetite and hematite), iron spinels enriched in Co, Cr, Cu, Mn, Ni, W, and Zn.