Polish Coal Research Articles

Long-term Analysis of the Effects of Production Management in Coal Mining in Poland

The primary aim of this article is to examine financial efficiency and work productivity, as well as their determinants, in selected Polish coal mines in 1998–2015. To achieve this goal, after introducing a justification for the choice of subject and the literature studies, the research methodology is presented, and research results are subsequently described and analyzed. Next, based on the main conclusions, model regularities and policy implications regarding efficiency and productivity improvement in Polish coal mining enterprises are established. The research for this study was conducted in five Polish coal mines, which were chosen on the basis of criteria aimed at ensuring the results’ comparability and the stability of organizational and mining conditions in the analyzed research period.

Natural Radioactivity in Polish Coal Mines: An Attempt to Assess the Trend of Radium Release into the Environment

The highly mineralised formation waters in the coal mines of Poland’s Upper Silesian Coal Basin contain natural radioactive nuclides, mostly radium. The 226Ra concentration in the groundwater that flows into the underground mine workings reaches 390 Bq/L, and is sometimes exceeded by the 228Ra concentration. The radium-bearing water sometimes also contain barium ions, which enables coprecipitation of barium-radium sulphate. Another type of radium-bearing water contains sulphate ions instead of barium; in this case, radium is transported to settling ponds and downstream. We have assessed the daily activity of radium in waters flowing into the underground mines and being discharged to the environment. Based on 1995 data, we estimate that the total activity of radium isotopes flowing into the mines was about 1300 MBq/day, while the radium activity in the discharge waters was about 700 MBq/day. A similar assessment performed with 2016 data indicated that the total activity in inflows was roughly 1150 MBq/day, while that discharged to surface waters was about 450 MBq/day.

Post-mining tourism in Upper Silesia and Czech-Moravian country

Europe experiences the development of post-industrial tourism documenting the time of growth of traditional coal basins. Contemporarily, the processes of deindustrialization take place. The material resources of traditional industry are being liquidated – which is expensive, or are adapted for the needs of tourism, which gives a new chance of development for these regions which are by rule in a difficult economic situation. Polish coal basin where many industrial plants and coal mines were closed as a result of restructurizing may serve as an example. Similar processes, although in smaller a scope, occur in the Czech Republic. Some of the industrial objects and coal mines concentrate certain values that predestine them to be included in the group of post-industrial heritage: the Czech and Polish coal mines from the 19th century, or coking plants and steel plants – as Hlubina in Ostrava Vitkovce. The idea of this article is to connect some Czech and Polish objects with one tourist route. The proposed tourist area starts in Czerwionka-Leszczyny and runs to Ostrava, and includes former industrial objects, old mines equipped with steam engines, patronage housing estates, coking plants, as well as mine waste dumps subjected to natural succession of vegetation. Creation of such route will allow to popularize the landmarks of post-industrial heritage for tourists of both countries, as well as will contribute to the development of services based on tourism. The route could become a common training ground for students of polytechnic departments of mining and environment protection, as it illustrates both the former mining technological processes and the processes of renaturalization of dumping grounds. The visiting sites were selected on the basis of unified criteria such as their age, suitability for tourism and education, as well as because of their originality, authenticity and uniqueness. The proposed tourist route will also connect the Polish Industrial Monuments Route with the monuments and mining museums in Ostrava.

Tests of steel arch and rock bolt support resistance to static and dynamic loading induced by suspended monorail transportation

Abstract At present, the suspended monorail systems constitute a very common means of transportation in the Polish hard coal mines. The main advantages of the suspended monorail include the independence of the route from the working floor surface irregularities and the possibility to transport cargo of significant mass and size. The masses and dimensions of machines and devices transported via monorail have increased considerably in recent times. This particularly concerns the transport of longwall system elements. In Poland, the maximum speed of suspended monorail travel is 2 m/s. Due to the fact that preparations are currently underway to increase the maximum speed above 2 m/s, it is necessary to inspect what influence it will have on work safety and mining support stability. Current operational experience and tests have shown that dynamic loads induced by the suspended monorail transportation have a significant influence on the roadway support stability, working protection durability and on the monorail operators. This is particularly true during the emergency braking of a suspended monorail by means of a braking trolley, where the overloads reach 3g. Bench tests of the selected steel arch and rock bolt support elements utilised in the Polish hard coal mines were conducted in order to determine the resistance of steel arch and rock bolt supports to static and dynamic loads. The article presents the results of the tests conducted on a steel arch support in the form of the sliding joints of an ŁP/V29 yielding roadway support, which is commonly employed in the Polish hard coal mines. Tests of elements of the threaded bolts with trapezoidal threads over the entire rod length were conducted as well. The conducted strength tests of steel arch and rock bolt support elements under static and dynamic loading have shown that dynamic loading has decisive influence on the support’s retaining of its stability. Support element stability decreases along with the increase of the impact velocity. This concerns both the steel arch support and the rock bolt support.

Environmentalism and Polish Coal Mining: A Multilevel Study

This paper, drawing on a questionnaire survey conducted among 587 coal miners from six coal mines, seeks to ascertain whether the Polish coal mining industry is committed to organizational greening and whether its employees behave in environmentally responsible ways. Specifically, it explores—by means of hierarchical linear modeling (HLM)—the direct effects of green organizational climates on miners’ pro-environmental conduct at home and at work. We found that climates had a direct effect on employee behavior in and outside the workplace, and that personal environmental values were positively related to the latter variable. However, it has to be admitted that the actual engagement of coal miners in voluntary pro-environmental action at work was not very deep. Crucially, it turned out that, in two coal mines, there were strong green climates, while the rest were weak, which suggests differences in terms of commitment to organizational greening throughout the industry. The present paper explores the significance of the results and highlights the applicability of our methodological approach to the study of employee involvement in organizational pro-environmental action.

State-of-The-Art Pulsating Jigs of KOMAG Type

For several decades the KOMAG Institute of Mining Technology has been involved in a construction of pulsating jigs - devices for a gravity beneficiation of hard coal. The conducted research and conceptual work enables their constant development, resulting in their high reliability and efficiency. The article presents the latest design solutions and examples of implementations of the KOMAG state-of-the-art pulsating jigs in the Polish hard coal mines. The operational principle and possibilities of an innovative control system of the KOGASTER SSWO jig node are also discussed

The influence of the type of fly ash on selected physical properties of their water mixtures (multiphase mixtures)

Waste from energy or mining has been widely used in civil engineering for many years, ie in road engineering, construction, land reclamation as well as in mining. The most frequently performed technologies in underground mining with fine-fraction waste are the sealing of infarcted grouting of cavings and liquidation. In these technologies, transport and migration properties play a primary role. They depend on the type of fly ash. At present, in Polish hard coal mines located in Upper Silesia, most commonly used technologies are ashes with code 10 01 02 from conventional boilers, and as second ashes from code 10 02 82 from fluidized bed boilers. The article presents the results of research on selected physical properties of ash-water mixtures such as: water-ash index (W/FA), leveling, density and volume of excess water. Furthermore, for the tested ashes, the volume of water was determined, which can be utilized in the case of the technologies described above, and it will constitute an added value.

Case Studies of Seismic Energy Release Ahead of Underground Coal Mining Before Strong Tremors

We would like to test the concept that induced seismicity prior to relatively large mining tremor (ML > 2.5, E > 106J) can be inferred from the cumulative Benioff strain release (BSR) as power law time-to-failure before the strong event. This study presents the application of accelerating BSR prior to a large earthquake, widely used in natural seismicity, for analysis of this phenomenon in induced seismicity. The Benioff strain release is quantified as accelerated releases of cumulative (square root sum) of seismic energy in the time series. During the study, five sequences were extracted from the seismic catalogues from two Polish hard coal mines: exhausted Bobrek Mine (data form the IS-EPOS Platform) and from a mine belonging to the Polish Mining Group. Next, a search radius was used to select precursory events and to indicate the type of processes occurring in the coal seam and its vicinity. The fitted power law of cumulative Benioff strain release showed changes of m-parameter. If the value of m was lower than 1.0, the process was regarded as an accelerating-like and if m was higher than 1.0—as a quiescence-like. The investigation of m-parameter vs. the search radius showed the general behaviour of the rock mass in the studied areas and allowed to evaluate the relationship between the critical radius and magnitude of the target event. The obtained scaling relation log(Rc) ~ 0.35 ML is similar to these reported by other authors who analysed natural seismicity which might suggest that the scaling relation works in a wide range of magnitudes.

Analysis of sorption and desorption of unsaturated hydrocarbons: Ethylene, propylene and acetylene on hard coals

Unsaturated hydrocarbons: ethylene, propylene and acetylene are released into the mine atmosphere as a result of the self-heating of coal. Their concentrations in the mine air is one of the indicators for assessing the degree of development of coal self-heating process. The sorption capacity of coals with respect to hydrocarbons may cause their concentrations to decrease in the mine air, which may affect the correct self-heating assessment. This phenomenon is particularly important in the case of coals with a significant sorption capacity.The paper presents the results of studies on sorption of unsaturated hydrocarbons: ethylene, propylene and acetylene carried out on six samples of Polish hard coals taken from the exploited coal seams. High-porous coals with a well-accessible pore system, large specific surface values, low metamorphism and high oxygen content are characterized by the highest sorption capacities. The hydrocarbon sorbed in the largest amount is acetylene, which is due to the smallest size of the acetylene molecule and its high reactivity. The amount of the sorption of ethylene and propylene is lower than that of acetylene and depends on the properties of the coals. Coals with high sorption capacities adsorb larger amounts of propylene than ethylene. For less sorbent coals, the opposite is true.The volume of sorbed hydrocarbons decreases with the increase of the sorption temperature from 298 to 373 K. The temperature has the greatest influence on the volume of sorbed acetylene, the smaller the ethylene. The gas that is the least sensitive to the temperature increase is propylene.On the basis of desorption studies, it has been found that the lowest degree of desorption from coals is displayed by propylene. Higher degrees of desorption were found for acetylene. Ethylene is desorbed the most from coals.The concentration of ethylene in the mine atmosphere is the most frequently used indicator of temperature increase in coal in the self-heating process.

Comparison of physicochemical, sorption and electrochemical properties of nitrogen-doped activated carbons obtained with the use of microwave and conventional heating

A series of new nitrogen-doped activated carbons has been obtained via the reaction with urea and chemical activation of Polish brown coal. In order to obtain nitrogen groups bonded in different ways to the carbonaceous matrix, the modification with urea was performed at two different stages of processing, i.e. precursor or char. Additionally, the effects of conventional or microwave heating on the physicochemical parameters, sorption abilities as well as capacitance behaviour of the carbons prepared were tested. All the materials under investigation were characterized by elementary analysis, surface area measurements as well as estimation of the number of surface functional groups. The sorption properties of the materials were tested towards methylene blue at temperature of 25 °C. Moreover, symmetric supercapacitors containing organic electrolyte and prepared carbons were tested in Swagelok® type cells by using CV, GCD and EIS methods. Depending on the variant of preparation, the final products were micro/mesoporous nitrogen-doped activated carbons of well-developed surface area ranging from 617 to 1117 m2/g, showing acidic or intermediate acid-base character of the surface and different contents of nitrogen functional groups varying from 1.0 to 5.6 wt%. The results obtained in this study showed that introduction of nitrogen and chemical activation of brown coal led to activated carbons with very good sorption capacity toward organic dyes as well as good electrochemical parameters. The specific capacitance was achieved up to 86 F/g for N-doped carbon obtained by microwave carbonization followed by chemical activation with potassium carbonate.

Analysis of the content of nickel, chromium, lead and zinc in solid products of coal combustion (CCPs) coming from Polish power plants

According to data from the European Environmental Agency (EEA), taking into account only the energy production and distribution sector, Poland emits almost 12.4% of chromium, 13.6% of nickel, 23.5% of lead and 28.9% of zinc annually when compared to the total emissions of these pollutants released by the EU Members (EU28) in this sector [1]. Coal combustion processes constitute one of the biggest emission sources of the above-mentioned elements into the environment. According to data found in the literature of the subject, the amounts of Cr, Ni, Pb and Zn in Polish hard coals from the Upper Silesian Coal Basin are 7.3, 9.8, 24.3 and 53.6 mg/kg, respectively [2]. During coal combustion these elements are mostly accumulated in bottom and fly ash. However, a large part of them is released into the atmosphere in the form of gases or particles associated with fly ash [3]. Identification of distribution of the above-mentioned elements between by-products from the coal combustion processes (CCPs) is necessary to develop effective methods of reducing the emission of these elements into the environment. In the article the content was determined of four ecotoxic elements (Cr, Ni, Pb and Zn) in coal blends, samples of fly ashes, ash-slag samples and products of desulphurization (gypsum and filter cakes) which came from two Polish fossil fuel power plants. The content of the elements in all samples was determined with the application of Atomic Absorption Spectrometry with Flame Atomization (FAAS).

Examinations of the sulfur emission from pulverized lignite fuel, under pyrolysis and oxy-fuel combustion condition

Problem of gas emission as NOX, SOX, heavy metals from fossil fuel combustion process is still under study. Especially the oxy-condition effect on gas emissions from oxy-fuel requires more analysis and research. This paper focuses on SO2 and SO3 behaviour investigation during air and oxy-fuel combustion processes, and formation of H2S and SO2 from N2 and CO2 atmosphere. The research focuses especially on Polish medium sulphur coals. In the paper selected brown coals were examined on the content of total sulphur. During the tests campaign one type of lignite, predried to Mraw = 15% was a subject of pyrolysis at 800 and 1000 °C under N2 and CO2 atmosphere, and further combusted in three different atmospheres: air atmosphere, and two different oxy atmospheres with O2/CO2 ratios, equal 25/75% and 30/70% (vol.). Tests were carried out on an isothermal flow reactors (IFR) in a large laboratory scale. The influence of the CO2 atmosphere in oxy-condition in comparison with to the air atmosphere on SO2, SO3 emission intensity was determined. The results showed that the change of atmosphere from the air atmosphere to oxy atmosphere and increase of oxygen concentration in O2/CO2 combustion atmosphere results in the increase of the conversion ratio ofsulphur from solid phase to a the gas phase for the lignite. During the pyrolysis process it is mainly the H2S that is released in the gaseous form.

Determination of random pore model parameters for underground coal gasification simulation

Gasification technologies represent the most viable options of thermochemical processing of solid fuels. They are also characterized by lower emissions and higher efficiency when compared to conventional combustion systems. Particular attention has been paid to underground coal gasification offering the possibility of utilization for energy purposes coal resources otherwise inaccessible for economic or safety reasons. The disadvantage of this process is, however, the difficult control both in terms of technological and environmental aspects. The underground coal gasification process requires investigation of numerous heterogeneous reactions and transport processes, influenced by various process parameters, such as the temperature, type and flow rate of a gasification agent and geological conditions of the georeactor. In the paper a new, alternative way of the determination of kinetics of coal gasification by the Random Pore Model application is proposed. The procedure for determination of model parameters is presented. The structural parameter was estimated on the basis of measurements of char porous structure parameters. The reactivity measurements made for selected Polish coals were applied in determination of kinetic constants. The results of gasification process simulations for determined parameters and Random Pore Model are also given.

Influence of selected factors of Polish coking coals on the Hardgrove Grindability Index (HGI)

ABSTRACT This paper presents the results of a study on the influence of selected parameters of coal on the Hardgrove Grindability Index (HGI). The samples used in the investigation came from the same Polish coking-coal mine. The samples varied in terms of their quality parameters, i.e., volatile matter, ash content, chemical composition, maceral composition, and vitrinite reflectance). The influence of the aforementioned parameters on HGI was assessed. It was found that, among the investigated coals, the mean random vitrinite reflectance value, a measure of the coal rank, was the parameter that had the most significant effect on coal grindability (positive correlation). Such a correlation was also found for the carbon and vitrinite content. However, for volatile matter, liptinite, and total sulfur content, a negative correlation was found. The content and chemical composition of ash (as a reflection of mineral matter) has no significant effect on HGI. There were some weak negative correlations observed between HGI and the SO3 and the TiO2 content of ash. Of the tested parameters, vitrinite reflectance has the greatest effect on HGI.

Analysis of distributions of various coal types properties by means of statistical methods

Coal can occur in various natural forms and its quality depends on its various properties. Polish coal mines extract and process various coal types, according to the Polish nomenclature. The paper presents an attempt of determining whether is possible to statistically differ the typical coal types occurring in Polish hard coal mines by means of traditional statistical tests. To this purpose three coal types, namely 31, 34.2 and 35 were selected from three Polish mines located in Upper Silesia. After appropriate preparation of the raw coals selected coal properties were examined, including combustion heat, ash contents, sulfur contents, volatile parts contents and analytical moisture. Then, by means of several statistical tests it was verified whether it is possible to prove statistically that these coal types differ significantly not knowing the type of distribution they represent. To this purpose such tests as Kruskal-Wallis test, test of series, Wilcoxon test and median test were applied. The results were statistically evaluated and the conclusions were made. The presented methodology may serve to compare not only coal types but also other raw materials.

Analysis of the Scale of Methane Hazard in Polish Hard Coal Mines

Abstract In the majority of Polish mines, the exploitation of hard coal is accompanied by the release of considerable amounts of methane. Being flammable and explosive, methane may form an explosive mixture with air once it appears in mine workings. For this reason, the methane hazard is recognised as one of the ventilation risks in the mining industry. This process leads to the formation of air and methane mixture, whose considerable amounts permeate into the atmosphere and the natural environment. This phenomenon is extremely unfavourable because methane is, besides carbon dioxide, yet another gas that exacerbates the greenhouse effect. For this reason, it is increasingly more common to equip mines with methane collection systems in the process of demethylation. These play a vital role for both the natural environment and the safety of work in mines. A reduction of the methane content in headings increases the safety of the working crew and enhances the effectiveness of mining production. The article presents an analysis of the methane-related hazard based on methane emissions during mining exploitation. The analysis was based on the data concerning the amount of methane emitted into the atmosphere and collected by methane extraction systems from 16 coal mines. It led to identification of homogenous mines with similar values of the absolute methane-bearing capacity and ventilation methane-bearing capacity as well as with similar amounts of methane collected by methane extraction systems. The analysis was performed using the non-hierarchical k-average method, which belongs to the group of algorithms for analysing clusters. As a result, the mines were divided into the assumed number of groups. The results obtained made it possible to determine a group of mines in which, in the Author’s opinion, similar systems can be applied for controlling and reducing the methane hazard. These results also open up numerous possibilities for undertaking joint business ventures by the mines in terms of using the collected methane and implementing preventive measures.

An Evaluation of the Functioning of Cooling Systems in the Polish Coal Mine Industry

Underground excavations in which an airflow is present are affected by both natural and technological sources of heat. As a result, the air flowing through the mine excavations is characterised by high temperatures, which—combined with high humidity—causes microclimatic conditions to deteriorate. Bad microclimatic conditions affect miners underground, causing a reduction of perception, concentration, attention, and perceptiveness. This negative influence of temperature and humidity on the human body is referred to as the climatic hazard. For this reason, the design of ventilation and air conditioning systems to be implemented in underground mining plants is an issue of increasing significance. This article investigates the performance of cooling systems in the Polish hard-coal mining industry. Based on the conducted research on air-cooling installations in six hard-coal mines, the actual efficiency of air-cooling is presented. The calculated values of cooling power were compared with the design intent. The obtained results have allowed identifying with greater precision the factors that diminish the efficiency of cooling systems in the mining plants under analysis. These factors may be treated on equal terms with key performance indicators (KPIs), which can be used to monitor the performance of cooling system components and to provide managers with high-level indicators on which decisions can be based.

Method for Assessing the Development of Underground Hard Coal Mines on a Regional Basis: The Concept of Measurement and Research Results

The functioning and development of the extractive industry depends on many unusual conditions that are not found in other industries, such as the size of deposits, the level of natural and technical hazards, geographic location, or the method of mineral extraction (open pit or underground). Therefore, it is difficult to use universal development assessment methods for such specific production units. As a result, the research undertaken in this article aims to develop an indicator method for evaluating the development potential of underground hard coal mines. This method is based on a theoretical and practical analysis of the conditions of functioning of hard coal mines, expert research, and multiple case studies verifying the operation of the presented development indicator. The first part of the article is devoted to identifying and analyzing the criteria for assessing the functioning of underground hard coal mines. Next, the essence and methodology of creating and interpreting the proposed indicator was presented. The second part of the article is empirical, and contains the results of the assessment carried out using the developed indicators for five Polish hard coal mines for the years 2011–2015. The results of the research indicate that the most important factors in the development of hard coal mines relate to the geological and mining conditions, and those concerning natural hazard levels. However, during the functioning, the financial conditions and related production conditions, which ultimately determine the survival and development of underground mining plants, gain in significance.

The implementation of Circular Economy Concept in the Polish Coal Combustion Products Sector – selected problems

The implementation of Circular Economy Concept in the Polish Coal Combustion Products Sector – selected problems

Active methods of mercury removal from flue gases

Due to its adverse impact on health, as well as its global distribution, long atmospheric lifetime and propensity for deposition in the aquatic environment and in living tissue, the US Environmental Protection Agency (US EPA) has classified mercury and its compounds as a severe air quality threat. Such widespread presence of mercury in the environment originates from both natural and anthropogenic sources. Global anthropogenic emission of mercury is evaluated at 2000 Mg year−1. According to the National Centre for Emissions Management (Pol. KOBiZE) report for 2014, Polish annual mercury emissions amount to approximately 10 Mg. Over 90% of mercury emissions in Poland originate from combustion of coal.The purpose of this paper was to understand mercury behaviour during sub-bituminous coal and lignite combustion for flue gas purification in terms of reduction of emissions by active methods. The average mercury content in Polish sub-bituminous coal and lignite was 103.7 and 443.5 μg kg−1. The concentration of mercury in flue gases emitted into the atmosphere was 5.3 μg m−3 for sub-bituminous coal and 17.5 μg m−3 for lignite. The study analysed six low-cost sorbents with the average achieved efficiency of mercury removal from 30.6 to 92.9% for sub-bituminous coal and 22.8 to 80.3% for lignite combustion. Also, the effect of coke dust grain size was examined for mercury sorptive properties. The fine fraction of coke dust (CD) adsorbed within 243–277 μg Hg kg−1, while the largest fraction at only 95 μg Hg kg−1. The CD fraction < 0.063 mm removed almost 92% of mercury during coal combustion, so the concentration of mercury in flue gas decreased from 5.3 to 0.4 μg Hg m−3. The same fraction of CD had removed 93% of mercury from lignite flue gas by reducing the concentration of mercury in the flow from 17.6 to 1.2 μg Hg m−3. The publication also presents the impact of photochemical oxidation of mercury on the effectiveness of Hg vapour removal during combustion of lignite. After physical oxidation of Hg in the flue gas, its effectiveness has increased twofold.