Coal reserves in the Czech Republic are estimated to be 10 billion tons – hard coal about 37%, brown coal about 60% and lignite 3%. Hard coal is produced in Northern Moravia. In 2017 the production of hard coal was 5.5 million tons. Brown coal is mined in North-Western Bohemia − the production of brown coal in 2017 was 38.1 million tons. Significant quantities of hard coal are exported to: Slovakia, Austria, Germany and Hungary. In accordance with the National Energy Policy, coal will remain the main source of energy in the country in the future, despite the increased use of nuclear energy and natural gas. The government expects that in 2030 energy from coal will account for 30.5% of energy produced. There are five coal companies in the Czech Republic: OKD, a.s., the only hard coal producer and four brown coal mining companies: Severočeské Doly a.s., owned by ČEZ, the largest producer of brown coal, Vršanská uhelná a.s., with coal resources until 2055, Severní energetická a.s. with the largest brown coal reserves in the Czech Republic and Sokolovska uhelná a.s., the smallest mining company extracting lignite. OKD operates coal in two mines Kopalnia Důlní závod 1 – (consists of three mines: ČSA Mine, Lazy Mine, Darkov Mine) and Mine Důlní závod 2 (ttwo mines Sever, Jih). The article also presents a pro-ecological solution for the management of waste heaps after coal enrichment – a plant for the enrichment of coal waste from the Hermanice heap.

The effective diffusivity of water in brown coal of Bełchatów mine was experimentally determined. The experiments were performed in superheated steam at 200°C and atmospheric pressure using slightly compressed pellets of cylindrical shape. The drying and temperature curves of the sample were used to identify diffusivity. An inverse problem was formulated and solved by the finite element method for 3D axially symmetric cylindrical geometry of the sample. A satisfactory fit of the simulated curves to experimental results was obtained. The obtained dependence of effective diffusivity on moisture content and temperature may be used in designing lignite dryers.

The paper is focused on the idea of a combustion modelling of a large-scale circulating fluidised bed boiler (CFB) during coal and biomass co-combustion. Numerical computation results for three solid biomass fuels co-combustion with lignite are presented in the paper. The results of the calculation showed that in previously established kinetics equations for coal combustion, some reactions had to be modified as the combustion conditions changed with the fuel blend composition. Obtained CO2, CO, SO2 and NOx emissions are located in borders of ± 20% in the relationship to the experimental data. Experimental data was obtained for forest biomass, sunflower husk, willow and lignite cocombustion tests carried out on the atmospheric 261 MWe COMPACT CFB boiler operated in PGE Turow Power Station in Poland. The energy fraction of biomass in fuel blend was: 7%wt, 10%wt and 15%wt. The measured emissions of CO, SO2 and NOx (i.e. NO + NO2) were also shown in the paper. For all types of biomass added to the fuel blends the emission of the gaseous pollutants was lower than that for coal combustion.

The transitional siliceous rocks from the Belchatow lignite deposit belong to the deposits with heterogeneous petrographic composition. The research allows us to identify among others, opoka-rocks and gaizes. The mineralogical-chemical analysis proves that the main ingredients of the studied rocks commonly used as building material are minerals of the SiO₂ group. Laboratory tests show that the nature of siliceous mineral phases has several effects on the geomechanical parameters of the studied transitional rocks. They are a reduction in water content and rock porosity, which leads to the transition of opal type A to opal type crystobalit and trydymit and then to quartz or microquartz. Their density and strength parameters are increased.

The quarrying industry is changing the local landscape, forming deep open pits and spoil heaps in close proximity to them, especially lignite mines. The impact can include toxic soil material (low pH, heavy metals, oxidations etc.) which is the basis for further reclamation and afforestation. Forests that stand on spoil heaps have very different growth conditions because of the relief (slope, aspect, wind and rainfall shadows, supply of solar energy, etc.) and type of soil that is deposited. Airborne laser scanning (ALS) technology deliver point clouds (XYZ) and derivatives as raster height models (DTM, DSM, nDSM=CHM) which allow the reception of selected 2D and 3D forest parameters (e.g. height, base of the crown, cover, density, volume, biomass, etc). The automation of ALS point cloud processing and integrating the results into GIS helps forest managers to take appropriate decisions on silvicultural treatments in areas with failed plantations (toxic soil, droughts on south-facing slopes; landslides, etc.) or as regular maintenance. The ISOK country-wide project ongoing in Poland will soon deliver ALS point cloud data which can be successfully used for the monitoring and management of many thousands of hectares of destroyed post-industrial areas which according to the law, have to be afforested and transferred back to the State Forest.

The new legislative provisions, regulating the solid fuel trade in Poland, and the resolutions of

provincial assemblies assume, inter alia, a ban on the household use of lignite fuels and solid fuels

produced with its use; this also applies to coal sludge, coal flotation concentrates, and mixtures

produced with their use. These changes will force the producers of these materials to find new

ways and methods of their development, including their modification (mixing with other products

or waste) in order to increase their attractiveness for the commercial power industry. The presented

paper focuses on the analysis of coal sludge, classified as waste (codes 01 04 12 and 01 04 81)

or as a by-product in the production of coals of different types. A preliminary analysis aimed at

presenting changes in quality parameters and based on the mixtures of hard coal sludge (PG SILESIA)

with coal dusts from lignite (pulverized lignite) (LEAG) has been carried out. The analysis

of quality parameters of the discussed mixtures included the determination of the calorific value,

ash content, volatile matter content, moisture content, heavy metal content (Cd, Tl, Hg, Sb, As, Pb,

Cr, Co, Cu, Mn, Ni, and W), and sulfur content. The preliminary analysis has shown that mixing

coal sludge with coal dust from lignite and their granulation allows a product with the desired quality

and physical parameters to be obtained, which is attractive to the commercial power industry.

Compared to coal sludge, granulates made of coal sludge and coal dust from lignite with or without

ground dolomite have a higher sulfur content (in the range of 1–1.4%). However, this is still an

acceptable content for solid fuels in the commercial power industry. Compared to the basic coal

sludge sample, the observed increase in the content of individual toxic components in the mixture

samples is small and it therefore can be concluded that the addition of coal dust from lignite or carbonates

has no significant effect on the total content of the individual elements. The calorific value

is a key parameter determining the usefulness in the power industry. The size of this parameter for

coal sludge in an as received basis is in the range of 9.4–10.6 MJ/kg. In the case of the examined

mixtures of coal sludge with coal dust from lignite, the calorific value significantly increases to

the range of 14.0–14.5 MJ/kg (as received). The obtained values increase the usefulness in the

commercial power industry while, at the same time, the requirements for the combustion of solid

fuels are met to a greater extent. A slight decrease in the calorific value is observed in the case of

granulation with the addition of CaO or carbonates. Taking the analyzed parameters into account,

it can be concluded that the prepared mixtures can be used in the combustion in units with flue gas

desulfurization plants and a nominal thermal power not less than 1 MW. At this stage of work no

cost analysis was carried out.

The article characterizes geological formations occurring in the Polish lignite deposits having the characteristics of raw materials, i.e. accompanying minerals, giving their location, quality characteristics, estimated resources and potential applications. Attention has also been paid to the economic suitability, e.g. in infrastructure works and for the reclamation of many geological formations found in the overburden, classified as so-called earth or rock mass. There are also raw materials of sorption properties representing a huge potential source of minerals valuable for the economy and environmental protection. This refers to e.g.: beidellite clays from Bełchatów, Poznań clays from the region of Konin and Adamów, lacustrine chalk from Bełchatów, as well as Mesozoic limestone from the lignite bedding in Bełchatów. The reasons for the unsatisfactory use of accompanying minerals have been given. The authors described the methods used in the mining operation and processing of associated minerals, also applicable in Poland, as the legal basis for the extraction of these minerals and the economic and financial conditions. They stressed the need to protect mined not associated minerals used by the construction of anthropogenic deposits. This activity primarily requires regulating the legal status of these deposits and the development and application of an economic and financial system that stimulates the economy of these minerals. In summary, the necessary actions were taken to increase the use of the accompanying minerals and their contribution to the balance of mineral resources in the country.

One of the parameters which enables the evaluation of carbonaceous material is the thermal effect of wetting. The value of the heat of wetting provides information about the surface energy and the texture of the materials immersed in the wetting liquid. Knowledge of the heat of wetting of the carbonaceous materials is used to research their sorption properties, to characterize the structure and to determine the surface area. A method of me asuring the wetting of the carbonaceous materials as one of the methods to evaluate the carbonaceous materials was proposed. On the basis of research which was conducted, one determined the heat of wetting black coal from the Brzeszcze mine by methyl alcohol and lignites from the Turów and Bełchatów mine. One of activated carbons furnished by the Gryfskand company (WD-extra) was selected for the purpose of the comparison. The enthalpy of immersion was calculated on the basis of the results, the surface of the carbonaceous materials that were studied. It was revealed that the energetic effects of wetting depend both upon the microporous structure and the chemical nature of the adsorbent. The greatest heat of wetting calculated per 1g of the carbonaceous material, which has the most developed surface area and micropore volume, was obtained for the activated carbon. However, the heat of wetting does not increase proportionally to the surface area. The study revealed that the thermal effects of wetting for fossil coal decreases with the increasing of the surface area. The linear relationship was obtained for the three samples which were studied. The highest thermal effects (ΔT) and heat of wetting (Q) among the fossil coals was determined for the lignite from the Bełchatów mine, even though this coal had the least-developed porous structure. One may discern a clear influence of the swelling process upon the measured thermal effects on the basis of this sample.

Fly ashes from the combustion of lignite coal are suitable materials for the creation of suspensions in which CO2 is bound by mineral carbonation. Considering their limited economic uses, mineral sequestration, as a stage of the CCS technology in lignite coal power plants, can be a way of recycling them. Mineral sequestration of CO2 was researched using fly ashes from the combustion of lignite coal in the Pątnów power plant, distinguished by a high content of CaO and free CaO. Research into phase composition confirmed the process of carbonation of the whole calcium hydroxide contained in pure suspensions. The degree of CO2 binding was determined on the basis of thermogravimetric analysis. A rise in the content of CaCO3 was found in the suspensions after subjecting them to the effects of carbon dioxide. Following carbonation the pH is lowered. A reduction in the leaching of all pollutants was discovered in the studied ashes. The results obtained were compared to earlier research of ashes from the same power plant but with a different chemical composition. Research confirmed that water suspensions of ashes from the combustion of lignite coal in the Pątnów power plant are distinguished for a high degree of carbonation.

The distribution of lignite deposits in Poland turns out to be closely related to tectonic boundaries and the occurrence of salt deposits. What mechanism underlies the connection between these elements?

Hard coal sludge is classified as group 01 waste or it is a by-product in the production of a hard coal with variable energy importance. Pulverized lignite is not waste but a final product of drying and the very fine pulverization of lignite with a high calorific value. The study comprised the basic material before granulation such as coal sludge (PG SILESIA) and pulverized lignite (LEAG) as well as their prepared blends after the granulation on a pipe vibration granulator designed at AGH. The pulverized lignite of the LEAG company shows a low sulfur contents. In the analyzed samples its average content (Stot d) is 0.61%. An average value of this parameter in the analyzed coal sludge samples is 0.55%. The addition of pulverized lignite does not have a significant impact on the total content of sulfur and of analyzed toxic elements (Hg, As, Cd, Cr, Co, Cu, Mn, Ni, Pb, Sb, Tl, and W) in the samples. The calorific value of coal sludge falls within the range of 11.0−12.4 MJ/kg (on a dry basis). For the coal sludge and pulverized lignite blends the calorific value clearly increases to values of 14.8−17.7 MJ/kg (on dry basis). The calorific value slightly decreases in the

Bełchatów lignite deposit is located in the central partof Poland in the tectonic Kleszczów graben. It is dividedinto several parts, which are mining fields: Kamieńsk area (eastern part of the deposit), Bełchatów area (central partof the deposit) and Szczerców area (western part of the deposit). The subject of this study was the Belchatow area.The main issue of the investigations was the dependence of local, regional and global, horizontal variability of selected lignite qualitative parameters (moisture, ash content, calorific value and sulfur content in the as receivedstate) is a function of viewing direction. There was applied the geostatistical analysis of the lignite variability parameters with use of semivariograms.

The researches which were conducted at different scales of observation: in the locale scale – in small field size8 ́8 m called experimental area (local analysis), in larger homogeneous separated parts of the Belchatow area(regional analysis) and in the whole Bełchatów area scale (general analysis). The results proved the visible anisotropy of variability mine lignite parametres. Anisotropy structure observed in regional and global scale isconnected with tectonic structure of the Bełchatów Graben. The detailed studies show the variated level of anisotropy observed in different areas of Bełchatów field.

However, no dependence of the relative level of ash and total sulfur content anisotropy on the environment of sedimentation of the main coal deposit in different parts of the Belhchatów field has been observed. Both parameters characterize with strong or medium anisotropy level in examined fields. Moreover, anisotropy is alsovisible in the local scale. Conducted researches confirmed the thesis that zonal anisotropy is prevalent kind of anisotropy in the regional scale. In the range of the whole deposit the total sulfur content showed zonal anisotropy,whereas the ash content revealed geometric anisotropy

The exploitation and processing of lignite in the Bełchatów region is connected with the formation of various mineral waste materials: varied in origin, mineral and chemical composition and raw material properties of the accompanying minerals, ashes and slags from lignite combustion and reagipsum from wet flue gas desulphurisation installations. This paper presents the results of laboratory tests whose main purpose was to obtain data referring to the potential use of fly ashes generated in the Bełchatów Power Plant and selected accompanying minerals exploited in the Bełchatów Mine in the form of self-solidification mixtures. The beidellite clays were considered as the most predisposed for use from the accompanying minerals , due to pozzolanic and sorption properties and swelling capacity. Despite the expected beneficial effects of clay minerals from the smectite group on the self-settling process as well as the stability of such blends after solidification, the results of physical-mechanical tests (compressive strength and water repellence) were unsatisfactory. It was necessary to use Ca (OH)2, obtained from the lacustrine chalk as an activator of the self-settling process It was necessary to use lacustrine chalk as an activator of the self-solidification process. The presence of calcium will allow the formation of cement phases which will be able to strongly bond the skeletal grains. Also, the addition of reagipsum to the composition of the mixture would contribute to the improvement of the physico-mechanical parameters. The elevated SO4 2– ion in the mixture during the solidification allows for the crystallization of the sulphate phases in the pore space to form bridges between the ash and clay minerals. The use of mixtures in land reclamation unfavourably transformed by opencast mining in the Bełchatów region would result in measurable ecological and economic benefits and would largely solve the problem of waste disposal from the from the operation and processing of lignite energy.

The main energy source in Poland is still hard coal and lignite. The coal combustion process produces large quantities of by-products, e.g. fly ashes, slag furnace and harmful chemical gases (CO2, NOx, sulfur compounds) which enter the atmosphere. Fly ashes, due to their being fine grained (cement-like), chemical and phase compound and reactivity, have also been widely used in various technological solutions e.g. in the production of ordinary cement, hydro-technical cement and the new generation of cements. The adequate amount of fly ashes additive has a positive effect on fresh and hardened cement slurry properties. What is more, it allows for the pro-ecological and economic production of cement mix The exploitation of natural resources is connected with performance mining excavations at different depths. After a certain period of time, those voids break down which, in turn, leads to the slip of upper layers and the so-called landslides forming on the surface. This situation imposes the necessity of basis and sealing rock mass reinforcement. To minimize the risk connected to geotechnical problems on the mining areas, there is a need to use engineering solutions which could improve soil bearing in a universal, economical and efficient way. This leads to the development of new cement slurry recipes used during geoengineering works, especially in the mining areas. Moreover, economic requirements are forcing engineers to use less expensive technical and technological solutions simultaneously maintaining strength properties. An example of such a solution is to use suitable additives to cement slurry which could reduce the total unit cost of the treatment.

The paper presents a brief outline of the European Union Climate and Energy Package in early 2020, as well as the EU’s plans in this respect until 2030 (Winter Package and Green Deal) and even further until 2050 (EU’s climate neutral target). Also the current condition of power generation in Poland and challenges for Polish energy sector in the nearest future are discussed. The Energy Policy of Poland until 2040 (EPP 2040) is analysed in relation to possible risks and dangers. Some improvements are proposed in regard to the implementation of the document. In addition, the current volume and perspectives of hard coal and lignite mining in Poland until 2040 are discussed and compared with an expected demand for coal in Polish power plants and combined heat and power stations. On the basis of the prognosis of energy consumption in the period 2031-2040, there seems to appear a serious risk of energy shortage due to a possible delay in a nuclear power project and lack of lignite mining at the level defined in EPP 2040 policy. Therefore, some variants of providing the security of energy supplies are taken into account and thoroughly analysed in the paper.

The problem of the migration of metal ions in the environment remains a current problem in light of the quality of obtained crops. The necessity of more and more frequent use of alternative sources of biogens in the form of waste substances, poses a threat of loading significant amounts of metals into the soil – including heavy metals harmful to human health and life. The article discusses a significant problem, namely the comparison of the results of the environmental impact of waste, obtained on the basis of legally authorized leaching tests (three-stage leaching test according to PN-EN 12457:2006), with results obtained from sequential chemical extraction (performed in 4-step chemical extraction developed and recommended in European Union countries by Communities Bureau of References – BCR). The study covered an investigation of industry fly ash from the combustion of lignite, in which Cu, Zn, Cd, Ni, Pb, Cr, Na, K, Li concentrations and loads were calculated. A mobility of analyzed elements was established on this basis. From heavy metals, the highest values in fraction I were noted for nickel and copper and zinc as well as nickel were noted for fraction IV . Peaking values of electrolytic conductivity in eluates was created by high concentrations of macroelements (Na and K). These tests confirm that the leaching tests used for their application in the natural environment indicate such concentrations at the highest levels that can be obtained at the first or second stage of sequential chemical extraction, and thus their proper full environmental impact is not known.

The aim of the study was to assess the possibility of using natural carbonaceous materials such aspeat, lignite, and hard coal as low-cost sorbents for the removal of Direct Orange 26 azo dye from an aqueous solution. The adsorption kinetics and the influence of experimental conditions were investigated. The following materials were used in the research: azo dye Direct Orange 26, Spill-Sorb “Fison” peat (Alberta, Canada), lignite (Bełchatów, Poland), and hard coal (“Zofiówka” mine, Poland). The morphology and porous structure of the absorbents were tested. Dye sorption was carried out under static conditions, with different doses of sorbents, pH of the solution, and ionic strength. It was observed that the adsorption of Direct Orange 26 dye on all three adsorbents was strongly dependent on the pH of the solution, while the ionic strength of the solution did not affect the adsorption efficiency. The adsorption kinetics were consistent with the pseudo-second-order reaction model. The stage which determines the rate of adsorption is the diffusion of the dye in the near-surface layer. The process of equilibrium adsorption of Direct Orange 26 dye on all tested adsorbents is best described by the Langmuir isotherm. The maximum adsorption capacity for peat, brown coal and hard coal was 17.7, 15.1 and 13.8 mg/g, respectively. The results indicate that peat, lignite, and hard coal can be considered as alternative adsorbents for removing azo dyes from aqueous solutions.

In-situ thermal upgrading modification technology is of great significance to lignite utilisation cleanly. It is an extremely complex multi-field coupling process. Therefore, it is necessary to study the physical properties of lignite under the thermo-mechanical coupling function. In this paper, the lignite pore evolution characteristics under thermal-mechanical co-function have been obtained at different scales based on experimental results. The mechanisms also have been deeply studied. The results indicated that lignite total porosity first increased and then decreased as the temperature increased from 23°C to 400°C under the triaxial stress of 7 MPa. The maximum value of 21.64% for the total porosity of lignite was observed at 200°C. Macropores were dominant when the temperature was lower than 100°C, while visible pores were dominant when at temperatures ranging from 100~400°C. The thermal weight loss and deformation characteristics of lignite were further studied using a thermal-mechanical testing platform. The weight loss and deformation process could be divided into three stages, namely the slow, rapid, and relatively slow stages. After being continuously pyrolysed for 5 hours at a temperature of 400°C, the maximum weight loss rate of lignite was 52.38%, the maximum axial linear strain was 11.12%, and the maximum irrecoverable radial strain was 18.79%. The maximum axial thermal deformation coefficient of lignite was −2.63×10 ⁻⁴℃ ⁻¹ at a temperature of 289°C. Macro-deformation and component loss were the main mechanisms of lignite structure evolution.

Many geological problems have not been convincingly explained so far and are debatable, for instance the origin and changes of the Neogene depositional environments in central Poland. Therefore, these changes have been reconstructed in terms of global to local tectonic and climatic fluctuations. The examined Neogene deposits are divided into a sub-lignite unit (Koźmin Formation), a lignite-bearing unit (Grey Clays Member), and a supra-lignite unit (Wielkopolska Member). The two lithostratigraphic members constitute the Poznań Formation. The results of facies analysis show that the Koźmin Formation was deposited by relatively high-gradient and well-drained braided rivers. Most likely, they encompassed widespread alluvial plains. In the case of the Grey Clays Member, the type of river in close proximity to which the mid-Miocene low-lying mires existed and then were transformed into the first Mid-Miocene Lignite Seam (MPLS-1), has not been resolved. The obtained results confirm the formation of the Wielkopolska Member by low-gradient, but mostly well-drained anastomosing or anastomosing-to-meandering rivers. The depositional evolution of the examined successions depended on tectonic and climatic changes that may be closely related to the mid-Miocene great tectonic remodelling of the Alpine-Carpathian orogen. This resulted in palaeogeographic changes in its foreland in the form of limiting the flow of wet air and water masses from the south and vertical tectonic movements.

Understanding the Cenozoic tectonic evolution of grabens rich in lignite is important in the context of the accumulation of ~40–650 m of peat, as well as the exploitation of later formed lignite seams with a thickness of ~20–250 m. Six such areas were selected for a detailed palaeotectonic analysis: the Gostyń, Szamotuły, Legnica, Zittau, Lubstów, and Kleszczów grabens. During the analysis, borehole data were used, taking into account the compaction of peat at the transition to lignite, in order to reconstruct the magnitude of the total subsidence. This made it possible to distinguish between regional (covering areas also outside the grabens) and local (occurring only in the grabens) tectonic movements, and among the latter, tectonic and compactional subsidence. The hypothetical palaeosurface of the mires was reconstructed based on the lignite decompaction. As a result, it was possible to determine whether the examined peat/lignite seams underwent post-depositional uplift and/or subsidence. Between one (Gostyń Graben) and four (Zittau Basin and Kleszczów Graben) stages of tectonic subsidence were distinguished in the studied lignite-bearing areas. In the case of the Zittau Basin, as well as the Lubstów and Kleszczów grabens, post-depositional stages of tectonic uplift were also indicated. Like the boundaries of lithostratigraphic units, the successive stages of the Cenozoic tectonic development of the examined grabens are diachronic.

Significant quantities of coal sludge are created during the coal enrichment processes in the mechanical processing plants of hard coal mines (waste group 01). These are the smallest grain classes with a grain size below 1 mm, in which the classes below 0.035 mm constitute up to 60% of their composition and the heat of combustion is at the level of 10 MJ/kg. The high moisture of coal sludge is characteristic, which after dewatering on filter presses reaches the value of 16–28% (Wtot r) (archival paper PG SILESIA). The fine-grained nature and high moisture of the material cause great difficulties at the stage of transport, loading and unloading of the material. The paper presents the results of pelletizing (granulating) grinding of coal sludge by itself and the piling of coal sludge with additional material, which is to improve the sludge energy properties. The piling process itself is primarily intended to improve transport possibilities. Initial tests have been undertaken to show changes in parameters by preparing coal sludge mixtures (PG SILESIA) with lignite coal dusts (LEAG). The process of piling sludge and their mixtures on an AGH laboratory vibratory grinder construction was carried out. As a result of the tests, it can be concluded that all mixtures are susceptible to granulation. This process undoubtedly broadens the transport possibilities of the material. The grain composition of the obtained material after granulation is satisfactory. Up to 2 to 20 mm granules make up 90–95% of the product weight. The strength of the fresh pellets is satisfactory and comparable for all mixtures. Fresh lumps subjected to a test for discharges from a height of 700 mm can withstand from 7 to 14 discharges. The strength of the pellets after longer seasoning, from the height of 500 mm, shows different values for the analyzed samples. The values obtained for hard coal sludge and their blends with brown coal dust are at the level from 4 to 5 discharges. The strength obtained is sufficient to determine the possibility of their transport. At this stage of the work it can be stated that the addition of coal dust from lignite does not cause the deterioration of the material’s strength with respect to clean coal sludge. Therefore, there is no negative impact on the transportability of the granulated material. As a result of mixing with coal dusts, it is possible to increase their energy value (Klojzy-Karczmarczyk at al. 2018). The cost analysis of the analyzed project was not carried out.

Power production is the largest source of emissions of anthropogenic carbon dioxide. The main fuels in Poland are solid fuels - hard coal and lignite. Their combustion produces large quantities of waste, primarily fly ash. The ashes from lignite, due to the chemical and phase composition, and thus their properties, have - so far - limited economic use. Among their possible applications is the use of mineral sequestration of carbon dioxide - this is the result of their relatively high content of active CaO and MgO, which can react with carbon dioxide in aqueous suspensions. The paper presents maximum theoretical capacity of CO2 bonding for examined fly ashes and the results of the research on absorption of CO2 by the ash-water suspensions from fly ash resulting from the combustion of lignite from Pątnów and Turów power plants. Calculated for the examined fly ashes maximum theoretical capacity of CO2 bonding amounted to 14% for the ashes from Pątnów power plant and 14.4% for the fly ashes from Turów power plant. Studies have shown that most CO2 - 8.15 g/100 g of ash, was absorbed by suspension with ashes from Turów power plant with a mass ratio of ash to water of at 0.8:1. In the case of ash from Pątnów power plant absorption was lower and amounted to a maximum - 8.7 g CO2/100 g ash. The largest increase CO2 absorption was observed in the first 30 minutes of carbonation in the suspensions of fly ash from Pątnów power plant and the first 15 minutes in suspensions of fly ash from Turów power plant. After this time, the absorption has increased slowly. An increase in temperature in the chamber system, confirming the occurrence of the process of carbonation and its endothermic character. The highest temperature - 44.8 C recorded in the suspension with ashes from Turów power plant, which has also the greatest absorption of CO2. The results confirm the usefulness of these ashes to sequester carbon dioxide.

Turkey has 19.3 billion tons of lignite reserves and the vast majority of these Neogene lignite deposits are preferred for use in thermal power plants due to their low calorific value. The calorific value of lignite used in thermal power plants for electricity generation must be kept under constant control. In the control of calorific value, the estimation of the lower and higher heating values (LHV and HHV) of lignite is of great importance. In the literature, there are many studies that establish a relationship between the heating values of coal and proximate and ultimate analysis variables. In the studies dealing with proximate analysis data, it is observed that although the coefficients of the obtained multiple linear regression models (MRM) are statistically insignificant, these models are used to predict heating values because of the meaningful correlation coefficient. In this study, it is investigated whether moderator variables are effective on LHV estimation with proximate analysis data collected from forty-one lignite basins in different regions of Turkey, and a moderator variable analysis (MVA) model is developed to be used for the prediction of LHV. As a result of the study, it is found that the proposed MVA model is in accordance with observation values (coefficient of determination R ² = 0.951), and absolute and standard errors are also small. Therefore, it is concluded that the use of MVA to estimate the LHV of Turkey’s lignite is found to be more statistically meaningful.

The Szamotuły Graben covers the southernmost part of the Permo-Mesozoic Poznań–Szamotuły Fault Zone. Along this regional discontinuity there are several salt structures, including the Szamotuły diapir, over which an extensional graben formed in the Paleogene and Neogene. The graben is located north of Poznań in central- western Poland, and is NW–SE-trending, ~20 km long, 3–5.5 km wide, and up to 160 m deep. It is filled with Lower Oligocene and Neogene sediments, including relatively thick lignite seams. Data from boreholes allow the assignment of the graben-fill sediments to appropriate lithostratigraphic units. Furthermore, analysis of changes in the thickness of these units provides evidence for periods of accelerated graben subsidence or uplift relative to its flanks. As a result, two distinct stages of tectonic subsidence and one inversion in the Paleogene–Neogene evolution of the Szamotuły Graben have been distinguished. Thus, relatively significant subsidence occurred in the Early Oligocene and the middle Early–earliest Mid-Miocene, while slight inversion took place in the middle part of the Mid-Miocene.