Coal Enrichment Research Articles

BINDERS FROM SECONDARY RAW MATERIALS OF COAL ENRICHMENT WASTE FOR CONSTRUCTION OBJECT ERECTION USING THE 3D PRINTING METHOD

Formulation of the problem. The 3D printing construction technology is one of the modern methods of rapid construction, which allows for a significant automation of the building process while achieving high precision in the fabrication of complex configurations using equipment (3D printers) controlled by software to define precise coordinates of the printed structure model. The main materials for construction 3D printing technology are composite mixtures based on binders. Cement or composite binders can be used as binders [1]. The cement production technology involves the firing of its components at 1 450 °C, which requires significant energy resources and affects its final cost and the overall mixture. The utilization of coal enrichment waste, which contains clay minerals, quartz, pyrite, and a small amount of carbonates, impurities, and combustible substances, allows for reducing the consumption of technological fuel and the firing temperature of the binder by harnessing the heat-generating properties of coal inclusions. Thus, coal enrichment waste can be used as a fuel component in obtaining the binder. The purpose. Based on the conducted research, it can be concluded that the use of component binders derived from coal enrichment waste shows promise in the construction of buildings using 3D printing technology. By harnessing the heat-generating properties of these waste materials, it is possible to reduce the consumption of technological fuel and firing temperature required for binder production, consequently lowering CO2 emissions into the atmosphere and reducing the final cost of the construction mixture for 3D printing.

Occurrence and Favorable Enrichment Environment of Lithium in Gaoping Coal Measures: Evidence from Mineralogy and Geochemistry

The Carboniferous-Permian coal measure strata in the Qinshui Basin exhibit highly lithium (Li) enrichment, with substantial exploitation potential. To further explore the enrichment mechanism of lithium in coal measure strata, the No. 15 coal of the Taiyuan Formation from the Gaoping mine is taken as the research object, and its mineralogical and geochemistry characteristics are evaluated using optical microscopy, X-ray diffraction, scanning electron microscopy, inductively coupled plasma mass spectrometry, X-ray fluorescence, and infrared spectral. The results show that the No. 15 coal is semi-anthracite coal with low moisture, low ash, low volatility, and high sulfur. Organic macerals are primarily vitrinite, followed by inertinite, and liptinite is rare; the inorganic macerals (ash) are dominated by clay minerals (predominantly kaolinite, cookeite, illite, and NH4-illite), calcite, pyrite, quartz, siderite, gypsum, and zircon. The average Li content in the coal is 66.59 μg/g, with higher content in the coal parting (566.00 μg/g) and floor (396.00 μg/g). Lithium in coal occurs primarily in kaolinite, illite, cookeite, and is closely related to titanium-bearing minerals. In addition, Li in organic maceral may occur in liptinite. The No. 15 coal was formed in the coastal depositional system, and the deposition palaeoenvironment is primarily a wet–shallow water covered environment in open swamp facies; the plant tissue preservation index is poor, and aquatic or herbaceous plants dominate the plant type. The reducing environment with more terrestrial detritus, an arid climate, and strong hydrodynamic effects is favorable for Li enrichment in coal. The results have important theoretical significance for exploring the enrichment and metallogenic mechanisms of Li in coal.

Assessment of Modern Restoration of Biogeocenoses in Reclaimed Areas with Coal Enrichment Waste

It has been found that areas of differentiated and undifferentiated technosoils with plant species diversity (from 21 to 26) are characterized by intense processes of vegetation restoration occurring in them. A gradual increase in the proportion of native species relative to ruderal species, as well as a gradual increase in species diversity, was noted. It was concluded that the ongoing processes of restoration of vegetation cover at the studied sites indicate the effectiveness of the reclamation work carried out using coal benefication waste.

Rare earth element enrichment in coal and coal-adjacent strata of the Uinta Region, Utah and Colorado

This study aims to quantify rare earth element enrichment within coal and coal-adjacent strata in the Uinta Region of central Utah and western Colorado. Rare earth elements are a subset of critical minerals as defined by the U.S. Geological Survey. These elements are used for a wide variety of applications, including renewable energy technology in the transition toward carbon-neutral energy. While rare earth element enrichment has been associated with Appalachian coals, there has been a more limited evaluation of western U.S. coals. Here, samples from six active mines, four idle/historical mines, four mine waste piles, and seven stratigraphically complete cores within the Uinta Region were geochemically evaluated using portable X-ray fluorescence (n = 3,113) and inductively coupled plasma-mass spectrometry (n = 145) elemental analytical methods. Results suggest that 24%–45% of stratigraphically coal-adjacent carbonaceous shale and siltstone units show rare earth element enrichment (>200 ppm), as do 100% of sampled igneous material. A small subset (5%–8%) of coal samples display rare earth element enrichment, specifically in cases containing volcanic ash. This study proposes two multi-step depositional and diagenetic models to explain the enrichment process, requiring the emplacement and mobilization of rare earth element source material due to hydrothermal and other external influences. Historical geochemical evaluations of Uinta Region coal and coal-adjacent data are sparse, emphasizing the statistical significance of this research. These results support the utilization of active mines and coal processing waste piles for the future of domestic rare earth element extraction, offering economic and environmental solutions to pressing global demands.

THE USE OF DIGITAL TWINS TO IMPROVE THE OPERATIONAL EFFICIENCY IN THE EXTRACTIVE INDUSTRIES

The article examines the impact of Digital Twins on the business processes of mining companies. Mining companies can optimise their operations, from stripping and mining to enrichment and transportation. By modelling different scenarios, identifying bottlenecks and making informed decisions, companies can improve resource efficiency, reduce downtime and increase productivity, making a positive impact on their operational efficiency. Predictive maintenance strategies implemented with the help of Digital Twins help increase efficiency by minimising unexpected equipment failures and maximising uptime.The main technological effects of the use of Digital Twins in the mining industry, which affect the operational efficiency of the company, are: (1) an increase in the volume of output of commercial products after coal enrichment; (2) an increase in the coefficient of output to the production line of mining equipment.These effects lead to an improvement in the operating efficiency of the mining company, which increases indicators such as EBITDA and cash balance at the end of the period. This impact on operating efficiency is achieved by increasing the volume of commercial products, improving the efficiency of production processes, and by reducing the fixed and operating costs of the business.In order to assess the impact of the use of Digital Twin technology on mining companies, a methodology has been developed to assess the impact of the use of Digital Twin technology on mining companies. According to the results of the survey, a number of key production processes have been identified where the introduction of a Digital Twin is expected to have an impact.As a result of the empirical study, the expected increase in EBITDA from the implementation of the Digital Twin was 28%, the actual increase in EBITDA over the study period was 21%. The expected increase in free cash at the end of the period was + 593 million rubles (+130%), the actual increase in free cash for the period under study was 441 million rubles (+96%).The introduction of Digital Twins in mining companies has shown great potential for improving operational efficiency and solving complex challenges facing the industry.

Geochemical Behavior and Enrichment Mechanisms of Arsenic in Low‐Rank Coal, Baiyinhua Depression, Erlian Basin

AbstractIn this study, the abundance of trace elements in Baiyinhua Depression coal and its relationship with the coal depositional environment was examined. (1) The content of arsenic in Baiyinhua Depression coal is that of a typically high arsenic coal from the late Mesozoic of China. The average arsenic content of Baiyinhua coal is 24.93 times, the highest being 132.71 times, that of Chinese coal. Coal rank is not a controlling factor affecting arsenic enrichment in coal. (2) Arsenic is primarily enriched in the syngenetic and diagenetic stages, the enrichment being most obvious in the syngenetic stage, with the intrusion of a magmatic‐hydrothermal solution in the epigenetic stage also providing rich sources of arsenic. (3) The Baiyinhua Coal‐forming plant material is mainly woody plants. The coal seam was covered with deep water, the oxygen supply was very weak, the bacteria very few, the sedimentary environment of the swamp relatively calm and the degree of damage to the woody plants is very low. The minerals in the coal are mainly quartz and clay minerals. The coal ash yield of Baiyinhua is small, with SiO2, Al2O3, MgO, K2O, TiO2, MnO and P2O5 mainly being combined in the inorganic minerals of the coal.

KHARKIV INSTITUTE OF TECHNOLOGY IN THE ESTABLISHMENT AND DEVELOPMENT OF INDUSTRIAL UKRAINE

The article solves the difficult task of restoring historical justice in relation to some representatives of the technical intelligentsia who were directly associated with the Kharkiv Institute of Technology in the period from 1890 to 1934. The importance of informative knowledge about the role of graduates of a higher technical educational institution for future generations, about their hard, dedicated work for the good of the country, has been proved. In the work, the authors reveal the personal contribution of its graduates to the development of certain regions of Ukraine, leading enterprises and industries in such cities as: Izyum, Zaporizhzhia, Kharkiv, Donetsk, Luhansk, Makiivka, Mariupol, Kramatorsk and other Ukrainian cities. The article extensively covers the names of graduates of the Kharkiv Institute of Technology - specialists in agricultural engineering, steam engine construction, tractor production, modernization of prototypes and the creation of the legendary T34 tank, specialists in coking and coal enrichment technologies, sugar industry, shipbuilding, brilliant scientists, architects, engineers of Kharkiv, who built and organized the cities of Ukraine - all those whose names should remind of heroic work and encourage Ukrainians to protect all their assets from the racist invasion.

Signal Processing from the Radiation Detector of the Radiometric Density Meter Using the Low-Pass Infinite Impulse Response Filter in the Measurement Path in the Coal Enrichment Process Control System

One of the most common coal preparations is enrichment in a jig using a float regulation system. The latest solutions propose to compensate for significant measurement errors of the float by introducing a radiometric density meter operating on the principle of gamma radiation absorption into the bottom product discharge zone of the jig. The signal from the radiometric density meter detector is in the form of a sequence of pulses with a Poisson time distribution, which are counted by a counter, as a form of digital low-pass filter. The requirement to maintain accuracy at an appropriate level forces the measurement time to be extended, which worsens the dynamic properties. Changes in the density of the coal–water medium have an unsteady, cyclical course, resulting from the principle of operation of the jig. The research goal was to develop an algorithm for processing the signal from the radiation detector using an IIR filter in the measurement path in a way that ensures optimization of the dynamic properties of the radiometric density meter operating in the control system of the coal enrichment process in the jig. For this purpose, a low-pass IIR filter was introduced into the measurement path to process the signal from the pulse counter. The identified course of the medium density for one cycle (the first) served as a reference signal. A first-order IIR filter was proposed, with a constant parameter selected on the basis of the reference signal and a parameter depending on the time derivative of the identified density of the medium. The mean squared error MSE was adopted as an indicator for assessing the dynamic properties of the radiometric density meter. The results of simulation tests showed that introducing an IIR filter into the measurement path gives better results in terms of the adopted criterion than using a counter with a constant measurement time. The best results (MSE = 2.05 × 10−4) were obtained using an IIR filter with a parameter that is a linear function of the derivative of the medium density over time, determined for one air pulsation cycle and applied in four subsequent cycles. These results were obtained for an adaptive first-order filter with a variable parameter a from the designated range from 0.833 to 0.999, for a measurement time of 2 ms.

IMPROVEMENT OF THE CLEANING SYSTEM OF OIL GAS FLOWS USING AN AERODYNAMIC INSERT

Air pollution is becoming a problem due to inefficient technological processes that accompany the mechanical processing of solid materials in various industries, including metalworking and woodworking, coal enrichment, coal burning in thermal power plants, metallurgy and construction materials industries. The problem is relevant for cement factories, since some of them use outdated equipment. Fine dust in this context becomes particularly important because the particle size of this dust affects the quality and grade of the concrete produced. Given the specifics of cement production and the goals of our research, which are to effectively collect small particles, it is important to note that wet cement production methods are not the best solution. The ideal solution for the problem of cleaning dust and gas flows in the cement industry is the use of a two-stage dust collection system, which combines an advanced cyclone and a bag filter. The system's periodic shaking mechanism allows for effective capture and control of fine dust particles, ensuring high quality cement production and reducing environmental impact. The combination of a cyclone, an acoustic coalescer and a block of bag filters, which is equipped with a periodic cleaning mechanism, as well as the addition of a system for collecting fine dust using a collector funnel, will split the collected dust into two fractions: fine (a = 10−5 to 10−7m) and coarse (a > 10-4m). The first fraction can be used to produce high-quality cement of high cost in the cement industry. The second fraction returns to the main technological process at its finishing stage.

Study on the Extraction Mechanism of Metal Ions on Small Molecular Phase of Tar-Rich Coal under Ultrasonic Loading

This study aims to elucidate the mechanism by which the ultrasonic loading of metal affects the extraction of small molecular phase substances (low molecular compounds) in tar-rich coal. Tar-rich coal samples were collected from the Huangling mining area in the southeastern Ordos Basin, China. The coal, the leaching solution of the coal, the extraction products, and the extraction residual coal samples with different metal ions loaded by ultrasound were analyzed using field emission scanning electron microscopy, pH detection, gas chromatography–mass spectrometry, a Fourier transform infrared spectrometer, and an X-ray diffractometer. The obtained results indicated that the ultrasonic loading of coal samples with different metal ions (Mn2+, Co2+, Cu2+, Fe2+, and Ni2+) promoted the extraction of small molecular phase substances in coal and increased the proportion of extracted aliphatic hydrocarbons, alkylbenzene, naphthalene, phenanthrene, and other compounds. The extraction rate of Mn2+ was the highest. Compared with the control group, the extraction rate was increased by 212%. After the ultrasonic loading of metal ions, the physical structure of the coal was loose and the contact area of the solvent increased; the degree of branching and the hydrogen enrichment of the residual coal decreased, the aromaticity increased, the interlayer spacing and stacking layers decreased, and the stacking degree and ductility increased. Metal ions exchanged with hydrogen ions in the coal molecules. At the same time, the metal ions were adsorbed in the coal molecules and effectively combined with free electrons in the coal molecules to catalyze; thus, the extraction effect of the small molecular phase of tar-rich coal was improved. This provides a new method for the clean and efficient utilization of tar-rich coal.

Методичний підхід до обґрунтування способу газифікації кам’яного вугілля для виробництва синтетичних моторних палив

The aim of the article is to substantiate the most suitable method of gasification of Ukrainian hard coal for further production of synthetic motor fuel. For this substantiation, a methodical approach has been developed, the use of which has allowed to obtain the following results. As a raw material base, the article recommends long-flame coal of the Western Donbass, located on the territory of the Dnepropetrovsk region, where powerful enterprises for the extraction and enrichment of coal operate. The most common methods of coal gasification in the world are analyzed: Lurgi (counter-current steam-oxygen gasification of large-lump coal (or briquettes) in a stationary bed), Siemens (direct-flow steam-oxygen gasification in the pulverized coal stream), Texaco (direct-flow oxygen gasification in the flow of coal-water pulp). For each of these methods, material balances have been developed; the composition and quality of the generated gas, the possibilities of organizing the production of the necessary energy resources, the level of emissions of harmful substances into the atmosphere and wastewater discharge have been evaluated. A methodology for calculating the composition of generator gas is proposed, which takes into account the composition of the blast (content of oxygen, water vapor or water). All calculations were performed for an enterprise with a coal capacity of 550 thousand tons of working weight per year. Based on the calculations and comparison of their results, the Texaco method is recommended for industrial implementation. The advantages of this method are as follows: the absence of a stage of steam production for gasification, the scarcity of the water cycle, which practically excludes the formation of wastewater, and the possibility of using contaminated water from other sources for gasification; the highest total content of hydrogen and carbon monoxide in the resulting synthesis gas; the maximum assimilated capacity of production reactors and the largest number of capacities created in the world using this technology; utilization of the heat of the resulting gas to obtain a large amount of electric and thermal energy.

Charcoal adsorbents for glycerin purification

The article is devoted to the research of the chemical composition of coals. The main goal of the research is to choose the method of its enrichment. The authors established that after the enrichment of coal, the ash content sharply decreased due to the washing off of its inorganic part. The process of coal enrichment, at a ratio of 1:2 (coal: water) has a positive effect on reducing the ash content by 1.3 times. Based on the data obtained, it was found out that the enrichment process in the coal production adsorbents is necessary to reduce their ash content. Based on the research a technological scheme for obtaining a carbon adsorbent and solutions for their regeneration were proposed.

Combustion Characteristics of Coal-Water Slurry Droplets in High-Temperature Air with the Addition of Syngas

An experimental study of the ignition and combustion processes of coal-water slurry (CWS) droplets based on coal enrichment waste in a high-temperature oxidizer at 650–850 °C with a syngas addition was carried out. The fuel slurry was a mixture of finely dispersed solid combustible particles (coal sludge, 10–100 µm in size) and water. The syngas was a product of biomass pyrolysis and two waste-derived fuels in a laboratory gasifier. Composition of the syngas was controlled by a precision analytical gas analyzer. The feasibility of co-firing CWS with syngas was experimentally established. Under such conditions, the CWS droplets ignition process was intensified by 15–40%, compared to fuel combustion without the addition of syngas to the combustion chamber. The greatest positive effect was achieved by adding the gas obtained during the biomass pyrolysis. The ignition delay times of CWS droplets are 5.2–12.5 s versus 6.1–20.4 s (lower by 15–39%) when ignited in a high-temperature medium without adding syngas to the combustion chamber. Based on the results obtained, a concept for the practical implementation of the CWS combustion technology in a syngas-modified oxidizer medium is proposed.

Particle travel rates and the enrichment of carbon in the sediment discharged by rain-impacted flows

Soil carbon losses from sheet and interrill erosion areas have an impact on the global carbon cycle. Sediment discharged in many experiments where artificial rainfall has been applied to sloping soil surfaces show greater proportions of carbon in the sediment than found in the cohesive soil source. In many cases, conclusions drawn from these experiments fail to recognise that the enrichment of carbon in the sediment discharge is a result of unsteady conditions that occur before the steady state develops. It is known that particles of sand of different sizes move at different rates when raindrop induced salation occurs with the result that initially the particle size distribution is finer than the source but tends towards that of the source as time progresses. The presence of carbon in aggregates influences the density of aggregates. Here a qualitative model of sediment transport of sand and coal particles by raindrop induced saltation is used to demonstrate time varying enrichment of coal resulting from the effect of carbon on particle settling velocity. The model also demonstrates how the layer of loose particles that develops on top of the cohesive soil surface influences the relative amounts of carbon and sand in the sediment discharges. The steady state is not achieved until the slowest moving particle detached at the farthest distance from the downslope boundary is discharged. That may not be achieved in many of the experiments reported in the literature.

Discovery of anomalous molybdenum enrichment in Ordovician and Silurian stone coal: Relevance, origin and recommendations

Molybdenum (Mo) is a strategic element but has a notably low concentration at the Earth's surface. Consequently, competition for molybdenum resources at the national strategic level has begun to emerge, and in recent years, large-scale mining has led to the gradual depletion of molybdenum deposit resources. Here, thirty-four element enrichment patterns of Ordovician and Silurian stone coals in central China are reported. Molybdenum is the most enriched element, with an average of 208 mg/kg (58.2–440 mg/kg), which is 99 times the global hard coal average, and this molybdenum enrichment is associated with Ba–Ga–U–Cr–Na–K–-Cu–Se–Zn enrichment and elevated SiO2, CaO, K2O, MgO, Na2O, MnO and P2O5 concentrations. These analyses reveal four stone coal samples with molybdenum concentrations of 260, 312, 403 and 440 mg/kg, which meet the grade for the molybdenum mineral exploitation formulated standard, indicating that the Ordovician and Silurian stone coal deposits should be considered promising alternative sources of molybdenum. The crude reserve estimate of molybdenum is approximately 29.2 × 104 tons. The anomalous molybdenum in the studied stone coal was sourced from a complex combination of hydrothermal fluids, original biomass and terrigenous materials. The unique paleogeographic location and geological structure in central China resulted in the anomalous molybdenum concentrations in the stone coal forming at that time, producing a unique type of coal-hosted molybdenum deposit. Future studies will consider the ecological effects of the molybdenum extraction mode and the cost savings effects of extracting molybdenum from stone coal. A comprehensive utilization plan is also needed. Next, a thorough study of molybdenum exploration related to black rock series must be performed to increase the total molybdenum resources and support Chinese international competitiveness.

Enrichment of sludge dump coal by spiral separation

The purpose of the presented research is to study the possibility of obtaining an additional coal product and ironcontaining concentrate from the sludge of a coal hydraulic dump. The research involved the study of the material composition of the initial sludge and technological tests. Material composition was examined using chemical, granulometric and mineralogical analyzes, the technological tests were conducted according to the gravitational-magnetic enrichment scheme. A spiral separator was used as the main enrichment equipment. Finishing operation was performed by the method of wet magnetic separation. Having studied the material composition, we determined that the initial sludge of the hydraulic dump is represented by 44.7 % of black coal and 43.32 % of brown coal. The bulk of hard coal is distributed in the size range of -2+0.25 mm and makes 51.15 %, brown coal is distributed in the size range of -2+0.25 mm in the amount of 13.32 %. The material is predominantly represented by a particle size of less than 0.25 mm with a high ash content in it. A coal concentrate with the ash content of 14.4 % was obtained as a result of technological tests. This product corresponds to the brand LFF (long-flaming fine). An iron-containing concentrate with the iron mass fraction of 64.7 % can be used in the metallurgical industry or in heavy-medium separation for coal enrichment. The study illustrates the possibility of obtaining high-quality secondary raw materials without additional mining costs using environmentally friendly technology.

БЕЗОТХОДНАЯ ТЕХНОЛОГИЯ УТИЛИЗАЦИИ ХВОСТОВ ОБОГАЩЕНИЯ ДОНБАССА

The prospects of waste-free utilization of coal enrichment tailings are considered. The concept of radical utilization of coal production waste with their inclusion in the natural cycle is detailed. The prospects of a new technology of metal leaching in high-speed mills with mechanochemical activation of processes are evaluated. The recommended technology provides an increase in the profitability of coal mining and radically solves environmental issues.

Origin and geochemical significance of antimony in Chinese coal

A total of 159 coal samples from different regions, periods and ranks across China were systematically analyzed for antimony (Sb) isotopic composition (ε123Sb), trace element contents and total sulfur content (TS) in this study. Here, we discuss the origin of Sb in coal from different regions of China. Antimony in coal from SW and NE China is primarily of hydrothermal fluid and leachate origins, respectively. In comparison, Sb in northern Chinese coal mainly comes from terrigenous materials and hydrothermal fluid. Antimony in coal from NW China may be influenced by the superposition of hydrothermal activity and leaching solution. Inorganic minerals (e.g., sulfide) and organic matter in coal are the determining factors for Sb enrichment in coal. The Sb isotopic fingerprint of Chinese coal is 2.46 ± 1.01 ε (weighted mean ± 1 SD, ranging from −4.45 to +9.72 ε). Accordingly, the isotopic composition of Sb in coal has great potential not only for researching Sb isotope fractionation in hydrothermal systems but also for tracing Sb release and transport in the supergene eco-environment. Furthermore, the establishment of Sb isotopic fingerprint for coal could largely reduce the uncertainty in the application of Sb isotope methods.

Use of a novel water separation process for the recovery of the mineral fraction from the stabilized organic fraction found in municipal waste.

Currently, the Stabilized Organic Fraction (SOF) 0-80 mm separated from the municipal waste stream is sent in its entirety to landfill in the mechanical-biological treatment plants operating in Poland. Such action does not align with the adopted EU strategy focused on waste management in the circular economy. This study aimed to assess the technical feasibility of the process of purification of mineral fractions with a grain size of 10-80 mm separated from SOF on a technological installation designed for glass recovery, built at the Marszów Plant. In terms of material, mineral fractions are a mixture of stones, rubble and glass, contaminated with various components, mainly organic. In 2020, the glass recovery installation was expanded with an innovative process of gravity separation to separate mineral fraction from SOF with the use of a jigging machine. A pulse jig used in the mining industry for coal enrichment processes was used for the first time in municipal waste management. The installation allows for the recovery of between 71.1 and 96.6% of mineral fractions contained in the input (84.8 ± 9.5% on average). The proportion of organics, plastics and other impurities in the waste is 4.1 ± 2.1% of the fraction mass. The process consumed water at an average rate of 0.34 ± 0.10 m3 tonnes-1 of treated waste and generated 0.26 ± 0.09 m3 tonnes-1 of wastewater. Electricity consumption averaged 1.20 kWh tonne-1 input.

TO THE QUESTION OF SCIENTIFIC SUBSTANTIATION OF THE CHOICE OF INDICATORS OF MANIFESTATION OF HAZARDOUS PROPERTIES OF COAL SEAMS

The article recalculates the quality indicators of coal for their working condition, taking into account the yield of ash and moisture content for coal seams, followed by an analysis of changes in the correlations between the indicators. The need to consider the fuel for its working condition is due to different end goals between establishing the consumer qualities of coal and the manifestation of the hazardous properties of coal seams. Different ultimate goals of the problems under consideration imply different ways of solving them, including differences between the influencing factors and their parameters. The methodology provides for the achievement of the goal to use the initial experimental data that have been accumulated over several decades based on the experience of using coal for industrial purposes. The condition and quality of coal after its preparation for use differs significantly from the condition in the mining area. These differences are associated with the preliminary enrichment of coal and the removal of a certain amount of mineral impurities. Based on conducted research out, the features of the choice of indicators of metamorphic transformations of coals were established, which are used in parallel, respectively, to establish the quality of fuel and predict the hazardous properties of coal seams. Discrepancies between the indicators of the degree of metamorphism used in the current regulatory framework for the safe conduct of mining operations and the state of fuel during mining operations in underground conditions are revealed. To improve normative documents on safe mining operations, it is necessary to consider indicators that characterize not only the organic (combustible) part of the fuel, but also the presence of mineral impurities and moisture in coals in the mining area. Keywords: coal, metamorphism, indicators, justification, mineral impurities, ratio, condition, dry, ashless, working, coal seams, mining, safety, regulatory framework, improvement.