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In this study, the radioactivity contents of Carboniferous Zonguldak-Kozlu hard coals, Carboniferous Antalya-Pamucakyayla hard coals and Pliocene Konya-Karapınar lignites were determined, then compared with the limit values determined by the authorized institutions and their hazard indexes were determined. The range of measured activity concentrations was from 16.2 Bq·kg−1 to 227.6 Bq·kg−1 for 238U, 20.6 Bq·kg−1 to 67.5 Bq·kg−1 for 232Th and 211.9 Bq·kg−1 to 515.5 Bq·kg−1 for 40K. The calculated mean absorbed gamma dose rate (D), radium equivalent activity (Raeq) and annual equivalent dose (AED) were 105.7 nGy·h−1, 227.9 Bq·kg−1 and 129.6 μSv·h−1, respectively. Although 238U and 232Th radionuclide activity concentrations are comparable to literature values, 40K activity concentrations were around three or four times higher than in UNSCEAR (2000) reports. As it poses a radiological risk, it is necessary to take the necessary precautions to reduce the negative effects on the environment and human health due to use of coals from Konya-Karapınar, Antalya-Pamucakyayla basins and to burn in a controlled manner.

For the first time, the distribution of rare earth elements (REE) has been studied in detail for a number of coal facilities (30 deposits, 650 samples of coal and 210 samples of carbonaceous rocks). The ubiquitous presence of elevated concentrations of REE in coals has been noted. The REE mineral cluster in coals includes the association: ash content of coals – SiO2 – K2O – Al2o3 – TiO2 – Sc – Y – Dy – Ho – Er – Tm – Yb – Lu, and the association La – Ce – Pr – Nd – Sm – Eu – Gd – Tb. The presence of these elements of the mineral part of the coals is preferably in the composition of phosphate minerals – monazite and apatite (according to electron microscopy with microanalysis, the correlation of REE with P2o5). The content of individual REE in humic acids isolated from coals and fractions of coals of different densities has been studied. The specific role of organic matter(s) in the concentration of REE, their presence in the humus component of S and in low-ash coals is shown. Selective accumulation (fractionation) of heavy REE by organic matter has been experimentally established for the first time. Two genetic types of REE mineralization have been identified in coals: mainly terrigenous (hydrogenic) and tufogenic. The increased concentrations of REE in coals are due to the influence of the petrofund. The deposits were ranked according to the degree of prospects for REE based on an assessment of the resource potential of associated REE in the coals of the studied brown coal deposits. REE raw materials (lanthanides in coal ash) differ significantly from traditional types of rare earths ores by an incomparably large relative amount of heavy REE (on average 3–4 times), sometimes reaching 46% of the total REE content. Thus, coal ash is a unique non–traditional source of heavy lanthanides – more rare, valuable and expensive. The coals of the studied deposits should be considered as associated raw materials for rare earths.

Ashless extracts, hypercoals, were obtained from Tuvan coals of the Ulug-Khem basin by dissolving them in N-methylpyrrolidone. The yield of the extracts was 27.3–79.4%, and their ash content was 0.5–0.8%. The composition of the products of pyrolysis, carried out at 420°C, of the initial coals and the hypercoals obtained from them was studied. It was found that high volatile bituminous coal (coal from the Elegest deposit) can be extracted most effectively. The qualitative and quantitative compositions of pyrolysis products were not fundamentally different in the initial coals and the corresponding extracts. According to TGA data, the decomposition of extracts (hypercoals) occurred at lower temperatures relative to that of the original coals with a high yield of volatile components. [ABSTRACT FROM AUTHOR]

The volatility of raw material prices and the rising prices of CO2 emission allowances when using fossil fuels to produce electricity and heat are still relevant problems for owners of generating units. The decision-making tools are used in the fuel purchase process. However, these tools should also consider environmental issues. The article’s main objective is a quantitative analysis of the potential for reducing costs associated with supplying and using hard coal in public power plants as a result of considering the costs of environmental protection and CO2 emission allowances in the process of planning this fuel supply. A mathematical model was developed to optimize the supply of hard coal for the power industry. The tool and elaborated research scenarios made it possible to calculate and analyze the impact of considering the costs of emissions of harmful substances into the environment and CO2 emission allowances on the planning of coal supplies and the reduction of costs related to acquiring and using coal by public power plants. The calculation results were presented on the example of the Polish power sector. The model’s results confirm that the appropriate selection of coals, taking into account the quality parameters determining the amount of emissions of harmful substances, reduces the amount of these emissions and the total costs of acquiring and using coal in electricity production. However, depending on the considered scenario, the scale of this impact varies. The results of the optimization of coal supplies to power plants and their proper interpretation may constitute an important contribution to making management decisions in energy companies. [ABSTRACT FROM AUTHOR]

Copyright of Praktyka Teoretyczna is the property of University of Wroclaw and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Bulletin of The Mineral & Energy Economy Research Institute of the Polish Academy of Sciences / Zeszyty Naukowe Instytutu Gospodarki Surowcami Mineralnymi Polskiej Akademii Nauk is the property of Mineral & Energy Economy Research Institute of the Polish Academy of Sciences and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Bulletin of The Mineral & Energy Economy Research Institute of the Polish Academy of Sciences / Zeszyty Naukowe Instytutu Gospodarki Surowcami Mineralnymi Polskiej Akademii Nauk is the property of Mineral & Energy Economy Research Institute of the Polish Academy of Sciences and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The geopolitical situation in Europe has changed dramatically due to the war waged by the Russian Federation in Ukraine. This makes it necessary to become independent from supplies of mineral resources, especially energy from Russia. According to the authors, ensuring Poland's energy security will require a longer use of coal as the primary energy resource than initially expected. The expected increase in energy demand may cause a negative energy balance in the country. Renewable energy sources dependent on weather conditions cannot with certainty ensure energy security. On the other hand, nuclear requires large financial outlays and a longer time for reactors' construction. In addition, it has other disadvantages (the problem of waste, environmental impact in the event of a malfunction and the need to import uranium). In these circumstances, coal may be a raw material that meets the economic needs and ensures the energy security of the country. [ABSTRACT FROM AUTHOR]

Environmental safety depends on the level of energy security development. Combustible minerals play a leading role in ensuring energy security. Solid combustible minerals make up a significant proportion in the total mass of combustible minerals. Currently, there is no single universal classification system for solid combustible minerals. Different countries use different systems for classifying coal by grade. At the same time, depending on the classification system, different sets of indicators are taken into account. The main energy accumulator in solid combustible minerals is carbon and a small amount of hydrogen. The energy of solid combustible minerals is directly dependent on the content of these chemical elements. To evaluate and compare different types of solid combustible minerals and their intraspecific differences, based on the presence of the optimal number of indicators of the main energy carriers, which are carbon and hydrogen, the conversion coefficient into conventional anthracite has been developed. The developed conversion coefficient of solid combustible minerals into conventional anthracite makes it possible to analyze the energy value of different types of solid combustible minerals, deposits, layers of solid combustible minerals, different grades of coal, operation of solid combustible mining enterprises, mining and processing enterprises, plants and factories processing solid combustible minerals, the state and prospects for the development of different levels of energy security. In the environmental safety system, the developed coefficient can be used in the development of computer simulation programs in creating protection systems to prevent combustion, fires and explosions in the extraction, use and processing of solid combustible minerals. The proposed option can serve as an additional variety to generalize and improve the existing classification systems, and to motivate to seek new approaches to further classification of solid combustible minerals

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.

Due to an absence of domestic certified reference materials for coal on the Polish market, an attempt was made to manufacture a new and innovative product tailored to its needs. The chosen candidate material was hard coal acquired from Poland’s coal mines. A single reference material unit consisted of 50g of an analytical hard coal sample with a grain size below 0.2 mm. A manufacturing method was developed enabling production of matrix reference materials addressing the needs of the domestic solid fuel market, and was directed at research laboratories carrying out analyses of solid fuels for the energy and coking sectors. The adapted manufacturing scheme of a certified reference material for coal was presented with a description of the chosen critical steps of the process and discussion of the obtained results in terms of homogeneity, stability, characterisation of the reference material as well as assigned values to particular properties and their uncertainty budget. The results obtained during homogeneity, short-term and long-term stability assessments as well as reference material characterisation confirmed the feasibility of the investigated certified coal reference material manufacturing process. The obtained levels of relative expanded uncertainties of the measurements confirmed the feasibility of the manufactured certified reference material for establishing and maintaining metrological traceability of measurement results. The presented research establishes a base for planning out production of additional reference materials as well as providing the know-how for designing manufacturing schemes for reference materials for solid fuels, or waste related materials like fly ash, or furnace waste.

The relevance of the study is determined by the search for new solid fuels to expand the fuel and energy complex and improve resource-saving and environmentally friendly energy. The main aim: a comprehensive study of cardboard and coal combustion, including the determination of the main characteristics of the combustion of solid fuel mixtures, the determination of the main kinetic parameters and the establishment of the role of the components in the mixture combustion. Object: solid fuel mixture based on Kaa-Khem coal and cardboard. Methods. Thermal characteristics of fuels are determined according to: analytical moisture – SS R 33503-2015; ash content – SS R 55661-2013; yield of volatile components – SS R 55660-2013; calorific value – SS R 147-2013; content of carbon, hydrogen, nitrogen – SS R 32979-2014; oxygen – SS R 27313-2015; sulfur – SS 8606-2015. The fuel combustion was studied using an SDT Q600 differential thermal analyzer (TA Instruments-Waters LLC, USA). Ignition and burnout temperatures were determined using the curve crossing method. To determine the kinetic characteristics of individual fuels and fuel mixtures, a method based on the Coates–Redfern model was used. Results. The heat of combustion of Kaa-Khem coal is twice that of cardboard, while the volatile content of cardboard is 1,8 times higher than that of coal, which makes cardboard a promising additional fuel. An increase in the mass fraction of cardboard in the mixture does not affect the ignition temperature of the mixture and is about 300 °С. The addition of 25 % cardboard to coal has a positive effect on coal carbon residue combustion, increasing the maximum reaction rate by 30 % compared to the calculated data. The activation energy in this case is reduced by 3 9%, the combustion index is reduced by 2,5 times. The results of this study can be applied in the design of new heat and power equipment, or be taken into account when converting coal-burning boilers to burning solid fuel mixtures.

Bulk density, porosity, and water retention capacity play a key role in limiting root growth and nutrient uptake in developed technogenic soils. Thus, the purpose of this study was to evaluate the impact of reclamation technologies and different vegetation types on vital physical soil properties formed from carboniferous materials. The case study was conducted on Sośnica hard coal post‐mine spoil heaps (Upper Silesian Coal Basin of Southern Poland). Nine experimental combinations of reclamation technologies and vegetation types were tested. For vegetation types and basic physical soil parameters, 120 plots (10 × 10 m) were selected. The texture analysis was done on composite soil samples collected at two uppermost soil depths (0–10 and 10–20 cm). Intact structure samples were collected into 100cm3 cylinders from the middle of each plot at both depths for bulk density (BD), porosity, capillary water capacity (CWC), and soil water storage (SWS). In the comparison of different reclamation scenarios, we noted that topsoiling increased BD, whereas CWC and porosity decreased. Spontaneous succession had the same effect on BD, porosity, and CWC as cultivation. Revegetation of the spoil heap with grasses and forbs resulted in lower BD and higher porosity and CWC in the top layer (0–10 cm), whereas woodland resulted in lower BD and higher porosity and CWC at lower depths (10–20 cm). The decreasing order of the SWS was grassland > forbland > woodland. Thus, forbs and grasses should be followed by tree planting, which is crucial to improving the hostile physical properties of the Carboniferous postmine soils. [ABSTRACT FROM AUTHOR]

The method of liquid filtration through a layer of coal powder was used for a comprehensive characterization of surface wettability in conjunction with the determination of the contact angle. The effect of the degree of chemical maturity (metamorphism) of coal on the filtration characteristics of a layer with fractured porous properties was evaluated. Different activity of coal surfaces to water wettability upon a change from the native state to the surface-oxidized one was established. It was shown that the wetting and filtration properties of the coal surfaces increased from native to surface-oxidized coals and decreased as the degree of metamorphism increased from low to medium metamorphosed coals. [ABSTRACT FROM AUTHOR]

Utilization of agricultural waste can be done by converting it with conventional fuels to energy. For this purpose, it is necessary to understand the properties of waste and its mixture with the fossil fuels important for its storage and conversion. The objective of the work was to examine the influence of moisture content and the composition of agricultural waste with hard coal mixtures on the mechanical and rheological properties of the waste. The materials tested were powdered biomass: dried distillers grains with solubles (DDGS), meat and bone meal (MBM), and hard coal (HC). Mechanical properties were measured to investigate flowability with the Jenike shear tester. A technique with an annular powder rheometer was applied for rheological measurements. It was shown that an increased moisture content worsened the flowability of the mixtures, while an increased biomass content reduced the influence of moisture and stabilized the mechanical properties of the mixtures in quasi-static conditions. In dynamic conditions, moisture decreased the mechanical strength of the mixtures and increased their flowability.

This study presents the results of concentrations of rare earth elements and yttrium (REY), uranium (U), and thorium (th) in ashes from combustion/co-combustion of biomass (20%, 40%, and 60% share) from the agri-food industry (pomace from apples, walnut shells, and sunflower husks) and hard coal. The study primarily focuses on ashes from the co-combustion of biomass and hard coal, in terms of their potential use for the recovery of rare earth elements (REE), and the identification of the sources of these elements in the ashes. Research methods such as ICP-MS (inductively coupled plasma mass spectrometry), XRD (X-ray diffraction), and SEM-EDS (scanning electron microscopy with quantitative X-ray microanalysis) were used. The total average content of REY in ash from biomass combustion is 3.55-120.5 mg/kg, and in ash from co-combustion, it is from 187.3 to 73.5 mg/kg. the concentration of critical REE in biomass combustion ash is in the range 1.0-38.7 mg/kg, and in cocombustion ash it is 23.3-60.7 mg/kg. In hard-coal ash, the average concentration of Rey and critical REY was determined at the level of 175 and 45.3 mg/kg, respectively. In all samples of the tested ashes, a higher concentration of th (0.2-14.8 mg/kg) was found in comparison to U (0.1-6 mg/kg). In ashes from biomass and hard-coal combustion/co-combustion, the range of the prospective coefficient (Coutl) is 0.66-0.82 and 0.8-0.85, respectively, which may suggest a potential source for REE recovery. On the basis of SEM-EDS studies, yttrium was found in particles of ashes from biomass combustion, which is mainly bound to carbonates. The carriers of REY, U, and th in ashes from biomass and hard-coal co-combustion are phosphates (monazite and xenotime), and probably the vitreous aluminosilicate substance. [ABSTRACT FROM AUTHOR]

Utilization of agricultural waste can be done by converting it with conventional fuels to energy. For this purpose, it is necessary to understand the properties of waste and its mixture with the fossil fuels important for its storage and conversion. The objective of the work was to examine the influence of moisture content and the composition of agricultural waste with hard coal mixtures on the mechanical and rheological properties of the waste. The materials tested were powdered biomass: dried distillers grains with solubles (DDGS), meat and bone meal (MBM), and hard coal (HC). Mechanical properties were measured to investigate flowability with the Jenike shear tester. A technique with an annular powder rheometer was applied for rheological measurements. It was shown that an increased moisture content worsened the flowability of the mixtures, while an increased biomass content reduced the influence of moisture and stabilized the mechanical properties of the mixtures in quasi-static conditions. In dynamic conditions, moisture decreased the mechanical strength of the mixtures and increased their flowability. [ABSTRACT FROM AUTHOR]

To study the particle size distribution and energy variation law of hard coal under a load, an impact compression test of hard coal specimens under different impact loading conditions was carried out using a Φ50 mm diameter Separate Hopkinson Press Bar (SHPB) test system. We implemented the theory of dynamic impact energy of rock to establish the calculation expression of hard coal impact crushing energy dissipation, and we established the Weibull distribution model of a crushing body to analyze the impact velocity in relation to the particle size distribution of hard coal crushing and crushing energy consumption. The results demonstrate that due to the different original states of the specimens, the damage to the specimens under static action is in the mode of conjugate plane shear damage, single bevel shear damage, and tensile damage. The damage process of the specimen under impact load loading is divided into three stages: elastic deformation, elastic–plastic deformation, and plastic softening, while the increase in the strain rate caused the peak stress of the specimen to increase. The Weibull distribution can characterize the impact crushing size distribution of hard coal specimens very well. The parameter of coal rock crushing degree is a power function that is influenced by the impact velocity; the greater the impact velocity, the higher the coal rock crushing degree, but the characteristic index of coal rock crushing fluctuates with the increase in impact velocity. As the impact velocity increases, the incident energy and reflected energy increase linearly, while the transmitted energy increases first and then decreases. The dissipation energy of coal rock crushing also increases linearly with the impact velocity. There is no obvious regular change between the energy dissipation rate of coal rock and impact velocity during impact damage, and the dissipated energy of macroscopic crushing only accounts for 10~20% of the incident energy; most of the energy is used for damping loss and damage loss. [ABSTRACT FROM AUTHOR]

Transition towards a cleaner and more sustainable environment is mainly driven by co-participation of households, whereas the residents’ transformation willingness is determined by various factors, including an environmentally-friendly attitude and greater public awareness. Simultaneously, the global push for a climate-neutral economy fuels the increasing emphasis on eco-consciousness and promotion of green investments. However, Poland still heavily relies on coal for energy production, despite the opportunities provided by the EU. Poland faces challenges in transitioning its households to cleaner energy sources, particularly due to historical conditions and the dominance of solid fuel boilers. This article shed light on the inefficiency of the energy transition process in Poland, presenting legal, economic, and social aspects. Despite multiple efforts, energy transition in Poland is not as buoyant as in other EU countries. Among the reasons for this phenomenon are the adverse behavior of residents, or government policies that favor the carbon-centric nature of the economy resulting in the low use of EU and state funds. This may lead to a continuation of the slower pace of change and eventually reaching the Frontier of development in Poland’s energy transition. The multitude of campaigns and initiatives encouraging Poles to switch to green energy should be underscored, but due to their scant ecological awareness and orientation towards economic rather than ecological considerations, existing measures should be reviewed. In view of the above, to ensure an effective transition, it is necessary to recognize and clearly define the incentives that would induce Polish households to use climate-neutral energy sources.Foreword: Monetary data has been standardized and, in view of this, the paper uses the euro (EUR) currency, including in places where the original data was given in a different currency. The exchange rate as of 12 June 2023 was used.

Copyright of Archives of Environmental Protection is the property of Polish Academy of Sciences and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Inzynieria Mineralna is the property of Polskie Towarzystwo Przerobki Kopalin and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Bulletin of The Mineral & Energy Economy Research Institute of the Polish Academy of Sciences / Zeszyty Naukowe Instytutu Gospodarki Surowcami Mineralnymi Polskiej Akademii Nauk is the property of Mineral & Energy Economy Research Institute of the Polish Academy of Sciences and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Environmental safety depends on the level of energy security development. Combustible minerals play a leading role in ensuring energy security. Solid combustible minerals make up a significant proportion in the total mass of combustible minerals. Currently, there is no single universal classification system for solid combustible minerals. Different countries use different systems for classifying coal by grade. At the same time, depending on the classification system, different sets of indicators are taken into account. The main energy accumulator in solid combustible minerals is carbon and a small amount of hydrogen. The energy of solid combustible minerals is directly dependent on the content of these chemical elements. To evaluate and compare different types of solid combustible minerals and their intraspecific differences, based on the presence of the optimal number of indicators of the main energy carriers, which are carbon and hydrogen, the conversion coefficient into conventional anthracite has been developed. The developed conversion coefficient of solid combustible minerals into conventional anthracite makes it possible to analyze the energy value of different types of solid combustible minerals, deposits, layers of solid combustible minerals, different grades of coal, operation of solid combustible mining enterprises, mining and processing enterprises, plants and factories processing solid combustible minerals, the state and prospects for the development of different levels of energy security. In the environmental safety system, the developed coefficient can be used in the development of computer simulation programs in creating protection systems to prevent combustion, fires and explosions in the extraction, use and processing of solid combustible minerals. The proposed option can serve as an additional variety to generalize and improve the existing classification systems, and to motivate to seek new approaches to further classification of solid combustible minerals. [ABSTRACT FROM AUTHOR]

Mining of hard coal creates large underground cavities, which significantly affect the subsurface and land surface. Observations of land surface behaviour after the closure of mines demonstrate that these threats do not disappear. During mine water rebound in the post-mining phase of underground coalmines, the water flows into the open mine workings and other altered or fissured areas. This paper provides early observations from the PostMinQuake project, which is designed to identify mechanisms, relevant parameters and dependencies of mining and geological parameters causing post-mining seismicity in several European coal regions. It also presents the correlation between seismicity and water table level in the studied basins that has been observed during the post-mining phase and shows the necessity of implementing new procedures to monitor these seismic events. [ABSTRACT FROM AUTHOR]

The aim of the research was to demonstrate differences in the content of trace elements (U, Th, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge, As, Se, Cd, Mo, Hg, Pb, W, Ba) in coal mined in Poland and coal imported from Russia, which are widely available on the market. Ecophile, cube and nut were selected for the research. Among them 3 come from Russia and 3 from Poland. The samples were mineralized and the heavy metal content was determined with the use of mass spectrometry with excitation in induced plasma. The research allowed us to conclude that the same carbon grades showed completely different metal contents and depended on the place of origin. The greatest amount of trace elements was found to be found in ecophysics from Poland (durin). Relatively large contamination with trace elements was also found in Polish peach (window) and in Russian walnut. A relatively high content of uranium was found in three samples, including the ecophyses. When burning coal, even of high quality, we expose the environment to the burden of trace elements, including radioactive elements present in their composition. Heavy metals from coal combustion constantly accumulate in the environment and so far no standards have been established for their content in this fuel.

To study the particle size distribution and energy variation law of hard coal under a load, an impact compression test of hard coal specimens under different impact loading conditions was carried out using a Φ50 mm diameter Separate Hopkinson Press Bar (SHPB) test system. We implemented the theory of dynamic impact energy of rock to establish the calculation expression of hard coal impact crushing energy dissipation, and we established the Weibull distribution model of a crushing body to analyze the impact velocity in relation to the particle size distribution of hard coal crushing and crushing energy consumption. The results demonstrate that due to the different original states of the specimens, the damage to the specimens under static action is in the mode of conjugate plane shear damage, single bevel shear damage, and tensile damage. The damage process of the specimen under impact load loading is divided into three stages: elastic deformation, elastic–plastic deformation, and plastic softening, while the increase in the strain rate caused the peak stress of the specimen to increase. The Weibull distribution can characterize the impact crushing size distribution of hard coal specimens very well. The parameter of coal rock crushing degree is a power function that is influenced by the impact velocity; the greater the impact velocity, the higher the coal rock crushing degree, but the characteristic index of coal rock crushing fluctuates with the increase in impact velocity. As the impact velocity increases, the incident energy and reflected energy increase linearly, while the transmitted energy increases first and then decreases. The dissipation energy of coal rock crushing also increases linearly with the impact velocity. There is no obvious regular change between the energy dissipation rate of coal rock and impact velocity during impact damage, and the dissipated energy of macroscopic crushing only accounts for 10~20% of the incident energy; most of the energy is used for damping loss and damage loss.

The content of natural methane in hard coal seams, called methane-bearing capacity, is the basic parameter that enables the level of methane hazard to be determined in hard coal mines. This parameter is also used to determine the potential quantities of methane that can be collected and used for energy purposes and the amount of its harmful emission to the atmosphere. Direct methods are most often used to determine methane-bearing capacity. An important aspect that has a great influence on the final result of the research is the gas losses generated at the stage of sampling. Under the conditions of the Polish mining industry, the direct drill cuttings method is used to determine the methane-bearing capacity. Gas losses are compensated for in this method with the use of the coefficient 1.12, by which the obtained result is multiplied. In this paper, a multi-parameter analysis of gas loss in the determination of methane-bearing capacity in hard coal seams has been carried out. Several experiments were performed to identify the most important aspects to be taken into account to obtain a correct result. A methane-bearing capacity test was conducted using two direct methods: the direct drill cuttings method, otherwise known as the single-phase vacuum degassing method, and a method based on the United States Bureau of Mines standards. Sorption studies, such as methane sorption kinetics tests, were also conducted in which sorption properties, such as sorption capacity, effective diffusion coefficient, and half sorption time, were determined. Methane sorption isotherms were also determined, and pore structure was analysed. Based on the obtained test results, an analysis was carried out which made it possible to present appropriate conclusions concerning the gas losses during the methane-bearing capacity test, generated at the stage of sampling. The final result of the work was the proposal of a new gas loss coefficient for the direct drill cuttings method of methane-bearing capacity determination. [ABSTRACT FROM AUTHOR]

The Young's modulus and Poisson's ratio, parameters reflecting the elastic response of a rock to stress, are the key parameters used in many engineering activities, such as hard coal mining and natural gas extraction. The objective of this paper was to present the results of complex laboratory measurements of the static and dynamic Young's modulus and Poisson's ratio for Upper Carboniferous hard coals from the Upper Silesian Coal Basin. The coals differed in geologic age (Mudstone Series—younger coals; Upper Silesian Sandstone Series—older coals) and petrographic structure (vitrain, clarain, and durain lithotype). Elastic parameters of the coals were determined following compression tests under a complex state of stress, as well as using the ultrasonic method in reservoir conditions. On this basis, linear functional dependences between parameters such as UCS, differential stress, confining pressure, strain rate, P- and S-wave velocities, and the static and dynamic Young's modulus and Poisson's ratio were determined. These dependences turned out to be linear, with strong and very strong correlation, as indicated by the high coefficients of determination, R2. These new results significantly broaden the knowledge of elastic properties of Carboniferous hard coals, especially in the field of geoengineering, underground coal gasification, and reservoir stimulation for coal bed methane extraction. [ABSTRACT FROM AUTHOR]

Aiming at the low efficiency of traditional mechanical cutting methods in hard coal seams, a multi-impact cutting technology was proposed, which was to design a hydraulic system inside the drum. In this paper, by analyzing the working process of the multi-impact drum, the corresponding mechanical model was established and the overall research plan was determined. A simulation experiment explored the working performance of the multi-impact drum under the action of multiple factors in cutting different hardnesses, using different impact frequencies and different drum speeds. The simulation results showed that the drum speed has the greatest influence on coal-breaking performance, followed by coal hardness, and the impact frequency of picks has the least influence on coal-breaking performance. In addition, a discrete element coal-breaking experiment with a traditional drum was carried out. The simulation results showed that the multi-point impact drum can improve coal-breaking performance by more than 20% compared with traditional drum in terms of coal-breaking capacity and cutting specific energy consumption. Finally, a simplified multi-impact drum industrial cutting test was carried out. The test results showed that the cutting resistance of the multi-impact drum was about 17.22% lower than when there was no impact. Considering that the simplified multi-impact cutting drum had a reduced impact pre-cracking effect on the coal, it can be considered that the results of the industrial test and the discrete element simulation test were still relatively consistent. The multi-impact cutting drum had good working performance under hard coal conditions. [ABSTRACT FROM AUTHOR]

The basic process of minerals’ mechanical preparation, including coal, is a beneficiation process which has a decisive impact on quantitative-and-qualitative parameters of commercial products. At present the products of the MBE-CMT, Allmineral and Tenova companies have big market shares as regards foreign water pulsatory jigs, as well as ITG KOMAG on the local Polish market. New implementations of jigs, developed at the KOMAG Institute of Mining Technology, for beneficiation of coking coal and steam coal in collaboration with Carbo-Eco Ltd. and Fugor Ltd. companies, were realized in 2019. Technical and technological parameters of new devices are described in the article. Supply systems of feed are presented as well as the method of collecting tailings and middlings. New design solutions, applied in modernized preparation plants, aimed at an improvement of jigs production capacity and efficiency are presented. In the case of each jig, after its activation and conducted adjusting processes, exact tests of a beneficiation efficiency were performed and their results are presented in the tabular form. Basic beneficiation accuracy indicators and parameters of products’ separation as well as balances of products are given. The test results, obtained from newly activated jigs, are discussed.

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The aim of the research was to demonstrate differences in the content of trace elements (U, Th, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge, As, Se, Cd, Mo, Hg, Pb, W, Ba) in coal mined in Poland and coal imported from Russia, which are widely available on the market. Ecophile, cube and nut were selected for the research. Among them 3 come from Russia and 3 from Poland. The samples were mineralized and the heavy metal content was determined with the use of mass spectrometry with excitation in induced plasma. The research allowed us to conclude that the same carbon grades showed completely different metal contents and depended on the place of origin. The greatest amount of trace elements was found to be found in ecophysics from Poland (durin). Relatively large contamination with trace elements was also found in Polish peach (window) and in Russian walnut. A relatively high content of uranium was found in three samples, including the ecophyses. When burning coal, even of high quality, we expose the environment to the burden of trace elements, including radioactive elements present in their composition. Heavy metals from coal combustion constantly accumulate in the environment and so far no standards have been established for their content in this fuel. [ABSTRACT FROM AUTHOR]

The present study examines the sorption of Cs (I) and Sr (II) on organic sorbents in the pH range from 2 to 10, as well as the mechanisms of their binding. In order to determine the influence of the physical properties and the quantity of functional groups of the organic sorbents on sorption, experiments were carried out on organic materials of varying degrees of metamorphism: high-moor peat, hard and brown coals and shungite. A detailed description of their mineral composition, cation exchange capacity, buffering capacity and elemental composition of sorbents is provided. XRD, XRF, SEM and BET adsorption methods were used for assaying. As a result of the conducted research, it can be concluded that Sr (II) showed a higher sorption per unit specific surface area than Cs (I) in the studied range of concentrations and pH values. Sr (II) sorption decreases in the following order: high-moor peat > brown coal > shungite > hard coal. The sorption of Cs (I) is highest on brown coal and lesser for high-moor peat, shungite and hard coal. It is suggested that Cs (I) and Sr (II) can be fixed on carboxyl functional groups and Cs (I), possibly, in insignificant amounts on phenolic hydroxyls of all four studied organic sorbents. [ABSTRACT FROM AUTHOR]

Of late, sustainable energy development has received considerable importance throughout the world due to the growing concerns regarding climate change and environment protection. This in turn, has led to the search for alternatives, which are ecofriendly and cost-effective. Turkey possesses vast resources of lignite and renewable energies, which if utilized properly can reduce the current energy deficit and imports from other countries. Though renewables have received more attention in the past few years; yet, the vast lignite reserves of Turkey cannot be averted while considering the major indigenous energy resources of the country. The present review briefly discusses the existing energy situation in Turkey with particular focus on the indispensable role of coal as a valuable energy resource in meeting the country’s growing energy demand. Biodesulphurization as a green treatment technique for sulphur removal from coal is discussed along with some of the recent advances made with respect to the Turkish lignite. A brief description relating to the impact of COVID-19 on the energy sector is also discussed. Furthermore, future outlooks towards sustainable development are presented.

An impact assessment of the run-of-mine dilution on hard coal production efficiency is presented in the article. The data were taken from three longwall faces, conducted in a thin seam. Empirical data were subject to a statistical analysis aiming at the development of a mathematical model of an advance of longwalls depending on a quality structure and an amount of the run-of-mine from the ploughequipped longwall faces. The Monte Carlo method, an analysis of agglomerations and an analysis of scenarios enabled to develop a mathematical model. Afterwards, an analysis of the economic efficiency of the mining process, bearing in mind scenarios assuming an improvement of the run-of-mine quality, was conducted. [ABSTRACT FROM AUTHOR]

Sixteen samples were designed for analysis (hard coal, aggregate - barren rock, hard coal sludge). The total mercury content and the amount of mercury leaching were determined. The percentage of leachable form in the total content was calculated. The studies were carried out under various pH medium. The leachability under conditions close to neutral was determined in accordance with the PN EN 12457/1-4 standard. The leachability under acidic medium (pH of the solution - approx. 3) was determined in accordance with principles of the TCLP method. The mercury content was determined by means of the AAS method. For hard coal the total mercury content was 0.0384-0.1049 mg/kg. The level of leaching on mean was 2.6%. At the acidic medium the amount of leaching increases to an mean 4.1%. The extractive waste of aggregate type features a higher total mercury content in the finest fraction < 6 mm (up to 0.4564 mg/kg) and a lower content in the fraction 80-120 mm (up to 0.1006 mg/kg). The aggregate shows the percentage of the leachable form on mean from 1.4 to 2.2%. With pH decreasing to approx. 3, the amount of leaching grows up to mean values of 1.7-3.2%. Coal sludge features the total mercury content of 0.1368-0.2178 mg/kg. The percentage of mercury leachable form is approx. 1.8%. With pH decreasing the value increases to mean value of 3.0%. In general, the leachability of mercury from hard coals and extractive waste is low, and the leachability in an acidic medium grows approx. twice. Such factors as the type and origin of samples, their grain composition, and the pH conditions, have basic importance for the process. The time of waste seasoning and its weathering processes have the greatest impact on increasing the leaching of mercury from the extractive waste. [ABSTRACT FROM AUTHOR]

The content of natural methane in hard coal seams, called methane-bearing capacity, is the basic parameter that enables the level of methane hazard to be determined in hard coal mines. This parameter is also used to determine the potential quantities of methane that can be collected and used for energy purposes and the amount of its harmful emission to the atmosphere. Direct methods are most often used to determine methane-bearing capacity. An important aspect that has a great influence on the final result of the research is the gas losses generated at the stage of sampling. Under the conditions of the Polish mining industry, the direct drill cuttings method is used to determine the methane-bearing capacity. Gas losses are compensated for in this method with the use of the coefficient 1.12, by which the obtained result is multiplied. In this paper, a multi-parameter analysis of gas loss in the determination of methane-bearing capacity in hard coal seams has been carried out. Several experiments were performed to identify the most important aspects to be taken into account to obtain a correct result. A methane-bearing capacity test was conducted using two direct methods: the direct drill cuttings method, otherwise known as the single-phase vacuum degassing method, and a method based on the United States Bureau of Mines standards. Sorption studies, such as methane sorption kinetics tests, were also conducted in which sorption properties, such as sorption capacity, effective diffusion coefficient, and half sorption time, were determined. Methane sorption isotherms were also determined, and pore structure was analysed. Based on the obtained test results, an analysis was carried out which made it possible to present appropriate conclusions concerning the gas losses during the methane-bearing capacity test, generated at the stage of sampling. The final result of the work was the proposal of a new gas loss coefficient for the direct drill cuttings method of methane-bearing capacity determination.

The Young’s modulus and Poisson’s ratio, parameters reflecting the elastic response of a rock to stress, are the key parameters used in many engineering activities, such as hard coal mining and natural gas extraction. The objective of this paper was to present the results of complex laboratory measurements of the static and dynamic Young’s modulus and Poisson’s ratio for Upper Carboniferous hard coals from the Upper Silesian Coal Basin. The coals differed in geologic age (Mudstone Series—younger coals; Upper Silesian Sandstone Series—older coals) and petrographic structure (vitrain, clarain, and durain lithotype). Elastic parameters of the coals were determined following compression tests under a complex state of stress, as well as using the ultrasonic method in reservoir conditions. On this basis, linear functional dependences between parameters such as UCS, differential stress, confining pressure, strain rate, P- and S-wave velocities, and the static and dynamic Young’s modulus and Poisson’s ratio were determined. These dependences turned out to be linear, with strong and very strong correlation, as indicated by the high coefficients of determination, R2. These new results significantly broaden the knowledge of elastic properties of Carboniferous hard coals, especially in the field of geoengineering, underground coal gasification, and reservoir stimulation for coal bed methane extraction.

Low-pressure sorption tests were carried out on samples of selected Polish bituminous coal in coal–methane and coal–carbon dioxide systems. The purpose was to determine the relationship between the petrographic composition of low-rank coal and the amount of gas stored in its porous structure and desorbed from it. The influence of the degree of coalification on the amount of sorbed gas was reduced to minimum, because isotherms of deposition and evacuation of gases were determined on the base coal samples and two concentrates of lithotypes, vitrain and durain, isolated from the original coal. It was found that the sorption capacity of carbon dioxide was related to the pertographic composition, but no such correlation was observed in regard to methane. Langmuir and Dubinin–Radushkevich sorption isotherms and the modified desorption model based on Langmuir equation were chosen. The applied equations gave a very good fit to the experimental data. Calculated parameters corresponding to free adsorption energy in the Dubinin–Radushkevich equation allow concluding on the independence of its mechanism from coal petrography and on the preference of carbon dioxide sorption. Calculated adsorption equilibrium constants in Langmuir's equation show variability with petrographic composition of coal and have lower values for methane than for carbon dioxide. It was shown that the size of the hysteresis loop depends on the petrographic composition of coal and increases with increase in vitrinite content for both sorbates, which was confirmed by values of areal hysteresis index and hysteresis parameter. [ABSTRACT FROM AUTHOR]

Copyright of Inzynieria Mineralna is the property of Polskie Towarzystwo Przerobki Kopalin and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)