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During this study, we investigated the mineralogical characterization of technogenic magnetic particles (TMPs) contained in alkaline industrial dust and fly ash emitted by coal burning power plants and cement plants. The reaction of tested dust samples varied between values of pH 8 and pH 12. Their magnetic properties were characterized by measurement of magnetic susceptibility (χ), frequency dependence of magnetic susceptibility (χfd), and temperature dependence of magnetic susceptibility. Mineralogical and geochemical analyses included scanning electron microscopy with energy dispersive spectroscopy, microprobe analysis and X-ray diffraction. The TMPs in fly ash from hard coal combustion have the form of typical magnetic spherules with a smooth or corrugated surface as well as a skeletal morphology, composed of iron oxides (magnetite, maghemite, and magnesioferrite) that occurred in the form of incrustation on the surface of mullite, amorphous silica, or aluminosilicate particles. The TMPs observed in fly ash from lignite combustion have a similar morphological form but a different mineralogical composition. Instead of magnetite and magnesioferrite, maghemite and hematite with lower χ values were the prevailing magnetic minerals, which explains the much lower magnetic susceptibility of this kind of ash in comparison with the ash from hard coal combustion, and probably results from the lower temperature of lignite combustion. Morphology and mineralogical composition of TMPs in cement dust is more diverse. The magnetic fraction of cement dust occurs mostly in the form of angular and octahedral grains of a significantly finer granulation (<20 μm); however, spherules are also present. A very characteristic magnetic form for cement dust is calcium ferrite (CaFe3O5). The greatest impact on the magnetic susceptibility of cement dust results from iron-bearing additives (often waste materials from other branches of industry), which should be considered the most dangerous to the environment. Stoichiometric analysis of micro-particles confirmed the presence of heavy metals such as Pb, Mn, Cd, and Zn connected with TMPs, which are carriers of magnetic signals in atmospheric dust. Therefore, in some cases, their presence in topsoil when detected by magnetic measurement can be treated as an indicator of inorganic soil contamination.

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The paper presents the results of studies on ashes produced from burning wood biomass in closed wood-fired furnaces, in individual household furnaces (Silesian Province, Poland). Dry sieve analysis and detailed granulometric analysis were performed with the Analysette 22 Micro Tec plus analyser. Content of the basic elements (Al, Si, P, Na, K, Mg, Ca, Fe) and potentially toxic elements (As, Pb, Cd, Zn, Cu, Ni, Cr, Hg) was determined by atomic absorption spectrometry (AAS) and inductively coupled plasma mass spectrometry (ICP-MS). Relative enrichment factors (REFs) were calculated for the elements (Pb, Cd, Zn, Cu, Ni, As, Hg, and Cr), and the emissions (E) of Pb, Cd, Hg, and As to the environment were estimated. The carbon content (40.2%–45.8%), H (3.7%–6.1%), O (46.2%–50.2%), N (0.12%–0.32%), and S (0.11%–0.96%) in wood biomass varies and depends on the wood species and drying period. The content of volatile parts in wood biomass ranges between 69.3 and 81%. Ash content varies between 2.6 and 18.3%. The wood calorific value ranges from 13.6 MJ/kg to 17.4 MJ/kg. Moisture content in the wood biomass ranges from 13.7% (briquette) to 46.7% (fresh birch). Identification of mineral composition and phases yields a high share of calcite, monetite, fairchildite, and quartz in the examined ashes. The combustion of wood biomass in fireplaces results in increased emissions of Pb and Cd to the atmosphere and may be the cause of introducing pollutants to waters and soils during ash storage.