Potential sources of rare earth elements are sought after in the world by many researchers. Coal ash obtained at high temperatures (HTA ) is considered among these sources. The aim of the study was an evaluation of the suitability of the high temperature ash (HTA ) formed during the combustion of bituminous coal from the Ruda beds of the Pniówek coal mine as an potential resource of REY . The 13 samples of HTA obtained from the combustion of metabituminous (B) coal were analyzed. The analyses showed that the examined HTA samples varied in their chemical composition. In accordance with the chemical classification of HTA , the analyzed ash samples were classified as belonging to the following types: sialic, sialocalcic, sialoferricalcic, calsialic, fericalsialic, ferisialic. The research has shown that the rare earth elements content (REY ) in examined HTA samples are characterized by high variability. The average REY content in the analyzed ashes was 2.5 times higher than the world average (404 ppm). Among rare earth elements, the light elements (LREY ) were the most abundant. Heavy elements (HREY ) had the lowest share. A comparison of the content of the individual rare earth elements in HTA samples and in UCC showed that it was almost 20 times higher than in UCC. The distribution patterns of REY plotted for all samples within their entire range were positioned above the reference level and these curves were of the M-H or M-L type. The data presented indicate, that the analyzed ash samples should be regarded as promising REY raw materials. Considering the fact that in 7 out of 13 analyzed ash samples the REY content was higher than 800 ppm, REY recovery from these ashes may prove to be economic.
Rare earth elements are characterized by the high risk of their shortage resulting from limited resources. From this reason REE constitute a group of elements of special importance for the European Union. The aim of this study was to evaluate ashes from the burning of coal in fluidized bed boilers as an potential source of REY . Twelve samples of fly ash and bottom ash taken from power plants in Poland were analyzed. Tests have shown that despite some differences in chemical composition, the fly ash and bottom ash from fluidized beds could be classified as the calsialic, low acid type. It was found that fly ashes contained more REY than bottom ashes. Among REY , the light elements (LREY ) had the highest share in the total REY content in both fly ashes and bottom ashes. Heavy elements (HREY ) had the lowest content. The normalized curves plotted for fly ash samples within almost all of their entire range were positioned above the reference level and these curves were of the L-M or H-M type. The content of the individual REY in these samples was even twice as high as in UCC . The normalized curves plotted for bottom ash samples were classified as of L, L-M or H type. They were positioned on the reference level or above it. The content of the individual REY in these samples was the same or up to about 4 times lower than in UCC. It was found that the content of critical elements and of excessive elements in fly ash and bottom ash differs, which has an effect on the value of the outlook coefficient Coutl, and which is always higher in the case of fly ash than in the case of bottom ash. Nevertheless, the computed values of the outlook coefficient Coutl allow both fly ash and bottom ash from fluidized beds to be regarded as promising REY raw materials.
The S-7 borehole log from the Sumina area (USCB Poland) revealed the presence of three basaltic veins originating from a basalt dyke. Coal interlayers in the rocks surrounding the basaltic veins have been coked to form natural coke. Photometric measurements revealed that the optical properties of the studied natural coke samples are characteristic of semi-graphite (Rmax > 9%). The natural coke matrix of all of the analyzed samples has a biaxial negative optical character. Vitrinite in the examined natural coke samples is characterized by a lower optical anisotropy than that of the natural matrix and it has a biaxial positive optical character. Vitrinite in almost all samples taken at locations more distant from the intrusion has a biaxial positive optical character. A reversal of the changes of the true maximum vitrinite reflectance and bireflectance with changing distance from the second basaltic vein has been observed. The temperature regime that acted upon the dispersed organic matter located in the immediate vicinity of the intrusion, estimated on the basis of the selected experimental data, is suggested to be higher than 750 °C.