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.

This article presents the results of the study of changes in mineral and chemical composition of artificial aggregates consisting of coal shale (a hard coal mining waste) and fluidized ashes. Such an aggregate was used for road construction. After completion of the construction works but before making the road available for public use, significant deformation of the surface in the form of irregular buckling of the asphalt layer occurred. It was excluded that this resulted from mining damage, design errors or performance mistakes, among others. A study of the materials that had been incorporated in the construction layers was undertaken in order to find the component and the mechanism responsible for the buckling of the road surface. A comparison of the mineral and chemical composition of aggregate samples collected from the embankment where the road buckled with the reference sample and samples from places without deformations showed that the bumps in the road embankment consisted of minerals that were not initially present in the aggregate. Wastes produced as a result of high temperatures (slag and power plants ashes, metallurgical wastes) are not as stable in terms of chemical and phase composition in the hypergenic environment. As a result of the processes occurring in the road embankment, anhydrite, which is the primary component of fluidized ashes, was transformed into gypsum and ettringite. As a result of contact with water CaO (present in fluidized ashes) easily changed into calcium hydroxide. As the crystallization of these minerals is expansive, it resulted in the filling of pores and, in extreme cases, in a substantial increase in the volume of the aggregate and, consequently, in the deformation of the road surface.

The Neogene basaltoid intrusions found in the S-7 borehole in the Sumina area (USCB) caused transformations of the adjacent Carboniferous rocks. The mineral and chemical compositions of the basaltoides are similar to those of the Lower Silesian basaltoides. The transformations that took place in the vicinity of the intrusion were manifested in the formation of natural coke, the secondary mineralization of these rocks (calcite, chlorite, zeolites and barite) and in the specific distribution of rare earths (REY). Among REY, the light elements (LREY) had the highest share, while the heavy elements (HREY) had the lowest share. Regardless of the lithological type of the analyzed rock, with increasing distance from the intrusion, the percentage of MREY and HREY elements increases at the expense of the light elements LREY. All analyzed distribution patterns of the REYs are characterized by the occurrence of anomalies, which often show a significant correlation with the distance of sampling points from the basaltoid intrusion. The specific distribution of REYs in the vicinity of the intrusion of igneous rocks is an indication of the impact of hydrothermal solutions associated with the presence of basaltoides on the rocks closest to them located at a temperature of over 200°C.

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.

The purpose of the study was determining of degree of contamination of soil cover as a result of disposing of different industrial wastes and comparison of the soil quality with quality of soils and the grounds described in standards in relation to the reclamation works carried out on the dump. Analysed waste dump belongs to the sparse objects of this type in the Upper Silesian Coal Basin, where both coal mining wastes as well as flying ashes occur.
During investigations there was done a collection of 9 soil samples around the dump using Egner`s cane from the depth of 30 cm. The content of heavy metals was determined (Cd, Co, Cr, Cu, Ni, Pb, Zn) using method of emission spectrometry (ICP-AES) and phase composition studies using the X-ray diffraction method (XRD ).
Obtained results enabled determination of impact of disposed wastes on the degradation of pedosphere of studied area, which represents III group of fallow lands. The contents of heavy metals in soil samples vary in wide spectrum, but do not exceed permissible content of metals and metalloids for the aforementioned soil group. The highest concentrations reaches iron (average content 0,6%), while concentrations of other elements do not exceed 0.02%. In the mineral composition of soil samples the dominant components are typical for soils in the area of post-mining dumps, i.e. quartz, feldspars, clay minerals, represented by kaolinite and illite. The presence of muscovite with a share of < 5% was also found. Minerals from the carbonate group – calcite (< 3.5%) and dolomite (< 0.3%) occur rarely. In the investigated samples there was identified presence of mullite, component typical for wastes coming from energy sector.

Fly ash which has been separated from the flue gas stream as a result of fossil fuels combustion constitutes a huge amount of waste generated worldwide. Due to environmental problems, many directions of their rational use have been developed. Various attempts to convert fly ash into sorption materials, mainly synthetic zeolites, are conducted successfully. In this paper, an attempt was made to convert fly ash from lignite combustion from one of the Polish power plants, using alkaline hydrothermal synthesis. The primary phases in the fly ash were: quartz, gehlenite, mullite, hematite, feldspar, lime, anhydrite, occasionally grains of ZnO phase and pyrrhotite, glass and unburned fuel grains. As a result of hydrothermal synthesis a material containing new phases – pitiglianoite and tobermorite was obtained. Among the primary ash constituents, only gehlenite with an unburned organic substance, on which tobermorite with crystallized pitiglianoite was present. As a result of detailed testing of products after synthesis, it was found that among the tested grains:

• two populations can be distinguished – grains containing MgO and Fe2O3 as well as grains

containing Fe2O3 or MgO or containing none of these components,

• the main quantitative component was pitiglianoite,

• pitiglianoite was present in larger amounts in grains containing Fe2O3 or MgO or in the absence of both components than in grains in which Fe2O3 and MgO were found.

The results of the study indicate that in post-synthesis products, the contribution of components were as follows: pitiglianoite – 39.5% mas., tobermorite – 54% mas., gehlenite – 3% mas. and organic substance – 3.5% mas.

The paper presents the results of hydrothermal zeolitization of fly ash from hard coal combustion in one of the Polish power plants. The synthesis was carried out using various NaOH fly ash mass ratio (3.0, 4.0 and 6.0) and the effect of NaOH concentration in the activating solution on composition of synthesized sample was tested. The process was carried out under the following permanent conditions temperature: 90°C, time – 16 hours, water solution of NaOH (L)/fly ash (g) ratio – 0.025. In the studied fly ash the dominant chemical components were SiO2 and Al2O3, while the main phase components were mullite, quartz and hematite, and a significant share of amorphous substance (glass and unburnt organic substance). After hydrothermal synthesis, the presence of unreacted fly ash phases was found in the products, as well as new phases, the quality and quantity of which depend on the NaOH to fly ash mass ratio used for synthesis:

 for ratio 3.0 – Na-LSX type zeolite and hielscherite,

 for ratio 4.0 – Na-LSX type zeolite, hielscherite and hydrosodalite,

 for ratio 6.0 – hydrosodalite and hielscherite.

The grains in all products of synthesis are poly-mineral. However, it was found that the new phases, overgrowing the unreacted phase components of fly ash, crystallize in a certain order. Hielscherite is the first crystallizing phase, on which the Na-LSX type zeolite crystallizes then, and the whole is covered by hydrosodalite. In the products of synthesis, the share of sodium-containing phases (the Na-LSX type zeolite and hydrosodalite) increases with the increasing concentration of NaOH in the solution used for the process.

This paper presents the results of a cost-effectiveness analysis and a cost-benefit analysis for the production of X-type zeolites from fly ash.
Positive results of the laboratory tests on the quality of zeolites derived from fly ash initiated a cost analysis on the production of this materials on an industrial scale. The cost-effectiveness analysis was conducted using the dynamic generation cost indicator (DGC). The calculated DGC expresses the technical manufacturing cost of 1 Mg of synthetic zeolites. Whereas the cost-benefit analysis (CBA) was completed using the economic net present value (ENP V) and the economic internal rate of return (EIRR ) indicators.
The calculated unit technical cost of producing 1 Mg of zeolites using an installation consisting of five reactors with a capacity of 25 m3 each is 211 EUR and is lower than the current market price of this product, including transportation costs. This proves the financial viability of the investment. The calculations of the economic efficiency of the installation (CBA method) show that it is fully economically viable to operate and use the products from a social point of view.