Coal Composition Research Articles

Occurrence, Removal, and Mass Balance of Polycyclic Aromatic Hydrocarbons and Their Derivatives in Wastewater Treatment Plants in Northeast China

Polycyclic aromatic hydrocarbons (PAHs), 33 methylated PAHs (Me-PAHs), and 14 nitrated PAHs (NPAHs) were measured in wastewater treatment plants (WWTPs) to study the removal efficiency of these compounds through the WWTPs, as well as their source appointment and potential risk in the effluent. The concentrations of ∑PAHs, ∑Me-PAHs, and ∑NPAHs were 2.01–8.91, 23.0–102, and 6.21–171 µg/L in the influent, and 0.17–1.37, 0.06–0.41 and 0.01–2.41 µg/L in the effluent, respectively. Simple Treat 4.0 and meta-regression methods were applied to calculate the removal efficiencies (REs) for the 63 PAHs and their derivatives in 10 WWTPs and the results were compared with the monitoring data. Overall, the ranges of REs were 55.3–95.4% predicated by the Simple Treat and 47.5–97.7% by the meta-regression. The results by diagnostic ratios and principal component analysis PCA showed that “mixed source” biomass, coal composition, and petroleum could be recognized to either petrogenic or pyrogenic sources. The risk assessment of the effluent was also evaluated, indicating that seven carcinogenic PAHs, Benzo[a]pyrene, Dibenz[a,h]anthracene, and Benzo(a)anthracene were major contributors to the toxics equivalency concentrations (TEQs) in the effluent of WWTPs, to which attention should be paid.

Reconstruction of the tail heating surfaces of CHP boilers in order to improve the efficiency

Recently, the share of non-design fuel use of coal at thermal power plants has increased, which negatively affects the operation of existing equipment. On the territory of the Irkutsk Region, there are 9 combined heat and power plants operating mainly on brown coals of the Irkutsk and Kansk-Achinsk basins. The main fuel at many CHPs is brown coal from the Mugunskoye deposit, the quality of which is deteriorating year by year. At the Novo-Irkutsk CHP, there is a prospect of continuing the supply of the Mugunsky coal with a sulfur content of up to 2.5%, which significantly exceeds the sulfur content of the design coals, which is 0.5%. This leads to the condensation of sulfuric acid vapors in the flue gases and, as a result, the heating surfaces are subject to sulfuric acid corrosion. In addition, there is a problem of erosive wear of air heaters at CHPs, caused by high flow rates and ash concentrations, which is also caused by a deterioration in the composition of the burnt coal. To solve the problem associated with low-temperature sulfuric acid corrosion of the boiler air heater tanks, it is proposed to place additional heating surfaces in the bypass gas ducts, which will reduce the temperature of the gases by cooling the flue gases with network water, and allow the obtained heat to be used in the added sections of the calorifier for heating the inlet (cold) air. While bypassing 25% of gases using the heat of gases in the calorifiers, erosion wear is reduced due to a decrease in the gas velocity in the air heater from 13 m/s to 9 m/s. The proposed technical measures will make it possible not only to increase the efficiency of the boiler and the plant as a whole, but also to increase the degree of fuel heat use.

DETERMINATION OF ASH CONTENT IN COAL BY X-RAY FLUORESCENCE ANALYSIS Authors D Baimolda

This article discusses the advantages of X-ray fluorescence analysis (XRF) techniques for the determination of ash in coal. The quality of coal depends on the amount of ash contained in it. On the other hand, ash causes irreversible environmental damage when using coal as a source of energy. Since coal is considered as the most important source of energy, coal quality is directly related to ash, which correlates with its non-combustible minerals and elements. Some elements such as S (sulfur), Ti (titanium), Ca (calcium), Fe (iron) after burning coal can have an adverse impact on the environment. Thus, we have demonstrated in this study how we can determine the ash content consisting of noncombustible minerals in the composition of coal and, thus, assess the quality of coal using X-ray fluorescence research. It also describes how we can determine coal ash samples using the XRF analyzer 123-1 in online, which is one of the most optimal methods in nuclear physics.

Geochemical and Mineralogical Characteristics of the Li-Sr-Enriched Coal in the Wenjiaba Mine, Guizhou, SW China.

This paper reports the mineralogical and geochemical compositions of C6 coal in the Late Permian Longtan Formation of the Wenjiaba Mine, Northern Guizhou in southwest (SW) China. The geochemical and mineralogical studies are the basis for the potential recovery of critical metals. The Longtan Formation, which is one of the major coal-bearing strata in SW China, contains dozens of coal seams. C6 coal is the main mineable coal seam in the Wenjiaba Mine and the whole coalfield. Proximate and ultimate analyses, inductively coupled plasma mass spectrometry (ICP-MS) and X-ray fluorescence (XRF) spectrometry on trace and major element concentrations, and X-ray diffraction and SEM-EDS analyses were carried out. Results suggest that this anthracite coal is characterized by low ash yield and medium sulfur content. The minerals are mainly composed of clay minerals (kaolinite, chlorite, illite, and mixed-layer illite/smectite), pyrite, and carbonates. Lithium is significantly enriched in C6 coal, with an average of 124 μg/g, and it has a higher concentration in the lower portion of the coal seam than that in the upper one. Strontium is significantly enriched in samples WJB-05 and WJB-06, with concentrations of 3030 and 4580 μg/g, respectively, but it is normal or just slightly enriched in other benches of C6 coal. Additionally, Cu, Nb, and Ta are slightly enriched in the coal. Lithium, dominantly hosted by kaolinite in C6 coals, has a recovery potential. Celestine is one of the major Sr-bearing minerals in C6 coal.

Relationship between coal composition, fracture abundance and initial reservoir permeability: A case study in the Walloon Coal Measures, Surat Basin, Australia

The Surat Basin, which is a major eastern Australian Coal Seam Gas (CSG) reservoir, produces gas from its Middle to Late Jurassic sub-bituminous Walloon Coal Measures, and shows variability in initial reservoir permeability across the basin. For a given lithostatic stress, the presence of vitrinite group or telovitrinite macerals within the coal can influence the fracture abundance within the coal reservoirs of similar rank, which in turn potentially impacts the initial reservoir permeability of the CSG reservoirs. The predictive relationship between megascopic banding character or lithotype, microscopic maceral composition and fracture intensity within CSG reservoirs is well explored in bituminous coals, but not so much in sub-bituminous coals. Here, we analyse wellbore image log data along with the conventional geophysical logs, maceral analysis data, core descriptions validated by core photos from the well completion reports and interpreted permeability data from well tests to systematically investigate the relationship between lithotype, maceral composition with a focus on vitrinite/telovitrinite, and fracture intensity in the sub-bituminous rank Walloon coals, to test their influence on permeability trends across the basin.Permeability-depth trends in the Walloon coals vary regionally across the basin, and show different inclinations depending on coal measures stratigraphy, coal lithotype composition, fracture intensity and stress orientation between local anticlines, monoclines and synclines. Depth normalised permeability and thickness-weighted telovitrinite content data from 55 wells were analysed. Furthermore, analysis of 3.8 km of borehole image logs, along with 156 maceral composition data points and thickness-weighted average lithotypes derived from the core description across 10 vertical wells, revealed a moderately positive relationship between the coal type and fracture abundance. This indicates some coal compositional control on the fracture abundance at this lower rank. The derived average total fracture intensity (cleat and sinusoidal coal fracture) from borehole image logs and thickness-weighted average telovitrinite content from the core analysis also exhibited an exponential increase, with the increasing depth normalised permeability derived from the well test data within the 10 analysed wells. This relationship suggests the influence of the variation in coal composition and fracture intensity on the rheological behaviour of the CSG reservoir within the Walloon Coal Measures. Spatial distribution of depth normalised permeability from the 55 wells across different domains and their relationship with the maceral composition within the study area also suggests the influence of geological structures on the depth normalised permeability. Therefore, though coal composition controls the fracture intensity, under favourable stress and fracture conditions the relationship can be substantially modified in parts of the Surat Basin, and altogether these factors control the rheological behaviour of the Walloon Coal Measures.

Geological Controls on Enrichment of Rare Earth Elements and Yttrium (REY) in Late Permian Coals and Non-Coal Rocks in the Xian’an Coalfield, Guangxi Province

The highly elevated concentrations of the rare earth elements and yttrium (REY), U, Mo, Se, and Pb in late Permian coals in some coalfields in Guangxi Province, South China, have been widely investigated; however, the mode of occurrence and enrichment mechanism of these critical elements are still under debate. This study investigates the mineralogical and geochemical compositions of coals and non-coal rocks from the Xian’an Coalfield in Guangxi Province to discuss the geological factors influencing the distribution of critical elements. The mineral in the studied coals consists mainly of quartz, and to a lesser extent, muscovite and kaolinite, with a trace amount of anatase. The coals are significantly enriched in REY, Pb, Se, Mo, and U and display the REY–U–Se–Mo–Pb-enrichment horizon (Horizon I) and U–Mo-enrichment horizon (Horizon II) adjacent to the host rocks or partings. The REY, U, Se, and Pb show organic association while Mo is primarily hosted by Fe-sulfides within Horizon I. The U and Mo have a phosphate affinity within Horizon II. Both the input of pyroclastic and epiclastic materials and the leaching of acidic solutions jointly govern the distribution of the REY–U–Se–Mo–Pb-enrichment horizon (Horizon I) and the U–Mo-enrichment horizon (Horizon II). The concentrations of REY in Horizon I exceed the cutoff grade of REY, and, therefore, the coals in the Horizon I can be regarded as promising raw materials of REY.

Effects of composition changes of coal treated with hydrochloric acid on pore structure and fractal characteristics

In order to investigate the influence of coal compositions on the pore structure, low temperature gas adsorption (LTGA) method was used to analyze the pore evolution of coal samples treated with hydrochloric acid. The results demonstrate that hydrochloric acid treatment significantly reduced the content of minerals and volatile matter in coal, which could increase the porosity and the pore connectivity of coal. The removal of volatile matter has an obvious reaming effect on supermicropores, but ultramicropores remained unchanged. The role of minerals in pores of different pore widths is different, which are the fillers in macropores, the skeletons of some large mesopores and the blockage in some small mesopores. With the decrease of minerals, the macropore volume increased, and the large mesopore volume first decreased and then increased. In addition, the opening of many closed small mesopores increased the fractal dimension D2 of pore structure complexity, and provides an increase in specific surface area, but it has no significant relationship with the fractal dimension D1 of pore surface roughness.

Preparation schemes of crushed coal for combustion in fluidized bed boilers using a gravity separator

The low concentration of nitrogen oxide during coal combustion in fluidized bed furnaces is due to the limited proportion of primary air in the combustion zone. The schemes applied for the preparation of crushed coal are mostly for the use of coal breakage screens with a fixed maximum particle size in the mixture. The primary air flow is limited to the conditions of the fluidization of the bed and can be reduced only by reducing the size of the particles fed into the furnace. With a constant particle size and lower boiler loads, the proportion of primary air and thus the concentration of nitrogen oxides in the flue gas increase. The use of separators to change the particle size has never been considered, since it is a priori assumed that the separators cannot provide the required disperse composition of crushed coal. To assess the possibility of using separators in the schemes of preparing crushed coal for combustion in a fluidized bed and to determine the necessary separation boundaries, variants calculations were carried out in respect to the coal preparation scheme for boiler No. 9 of the Novocherkasskaya hydro-power plant. It is shown that the disperse composition of the fine separation product in the gravity separator with overturning shelves along the 5 mm boundary is identical to the disperse composition of crushed coal obtained in the scheme with a screen and crusher. The dependence of the maximum particle size of crushed coal on the separation boundary of the separator is given. It is shown that in the scheme of preparation of crushed coal for combustion in a fluidized bed, replacement of screens with gravity separators will not lead to violation of the requirements for the dispersed composition of crushed coal. At the same time, the proposed replacement allows you to quickly change the maximum particle size of crushed coal during operational activity and thereby to maintain the optimal fraction of primary air when the boiler load changes.

New data on brown coal occurrences in the Yamutarida and Dyuntaturku-yamu river basin in the northern part of the Yenisei-khatanga trough

Background. New information was obtained on brown coal occurrences in the northern part of the Yenisei-Khatanga trough (Lake Taimyr area). This region continues to attract the attention of geologists and oil producers due to its established oil and gas potential.Aim. To study the lithological features of rocks and material-petrographic composition of coals from a new promising area of the Yenisei-Khatanga trough in northern Russia.Materials and methods. A set of geological, lithological, and petrographic research methods was used to study a series of samples of coals and host rocks. Measurements were carried out on a QDI-302 Craic Spectrophotometer microscope with a 50× objective lens according to the standard methodology ISO 7404-5 in reflected polarised light using a Spinel standard (Ro = 0.426%) in oil immersion. X-ray fluorescence analysis was performed using a Respect device with an energy dispersive spectrometer without vacuum, having an X-ray tube with a silver anode (registration of elements only from K to U). Anode voltage — 30 kV. Current — 0.3 mA. Exposure time (τ) — 300 s. Y axis — intensity of characteristic lines, rel. unitsResults. The lithological features of the studied samples were elucidated, and the material-petrographic composition of the coals was studied. In the spore-pollen assemblage from the studied deposits, the dominant associations were determined by the predominance of two-bag pollen of Disaccites (Pinaceae) conifers. On this basis, the age of the Begichevskaya Formation rocks was established as belonging to the Albian and Cenomanian stages of the Lower-Middle Cretaceous.Conclusion. The degree of variability of coals was estimated; their grades (technological groups) and the trace element composition of ash were determined. The reflection values of vitrinites were measured in order to clarify the stage of changes in brown coals and obtain the quantitative characteristics of their quality. The reflection values of vitrinites (Ro) are from 0.32 to 0.52%, which corresponds to the stages of brown coal changes, technological groups 1B—3B.

Elucidation of elemental and structural changes in high-volatile bituminous coal during thermal treatment by X-ray diffraction and terahertz time-domain spectroscopy

Research on the chemical composition and structure of coal is fundamental for understanding chemical reactivity in combustion, pyrolysis, and gasification processes. In this work, X-ray diffraction (XRD) and terahertz time-domain spectroscopy (THz-TDS) are used to investigate both the chemical structural characteristics and thermal evolution of high-volatile bituminous coal subjected to different heat treatments. The XRD spectra indicate that aromaticity (fa) and coal rank (I26/I20) increase with temperature, which is consistent with elemental analysis. However, the structural parameters, such as interlayer spacing (d002), lateral size (La), and stacking height (Lc), show weak changes. Combined with the element analysis and XRD results, THz-TDS is carried out to characterize the above samples more precisely and further elucidate their chemical and structural changes. The study demonstrates the capability of the THz technique to determine and characterize the structural parameters and chemical compositions to evaluate coal rank and classification.

PECULIARITIES OF LEAD DISTRIBUTION IN COAL SEAMS OF DONETSK-MAKIIVKA GEOLOGICAL AND INDUSTRIAL AREA OF DONBAS

Increasing requirements for monitoring and environmental protection, especially in the coal-mining regions of Ukraine, where a large number of industrial enterprises are concentrated, necessitates new scientifically based methods for predicting the content of toxic and potentially toxic elements in the rock mass that mined from the mines, in the coal wastes. and coal upgrading, as well as the impact of the coal industry and heating enterprises on the ecological state of the environment. For this purpose it is necessary to have data about concentration, character and peculiarities of the distribution of toxic and potentially toxic elements, including lead in the coal seams.The article presents the results of research covering the whole territory of one of the most studied geological and industrial areas of Donbas – Donetsk-Makiivka for the period from 1983 to 2014. The peculiarities of the distribution are considered and the character of lead distribution in 52 coal seams is determined, the weighted average concentrations of this element are calculated both in the coal of the main working seams and in 7 suites of the middle and upper series of coal period.It is proved that the accumulation of lead in the coal of the main working seams of the Donetsk-Makiivka geological and industrial area is polygenic and polychronic. The change in its concentration in section and area is mainly due to tectonic and facies features of coal-bearing strata formation, controlling the petrographic composition of coal, hydrodynamic regime of the peat accumulation basin, lithological-facies composition of the immediate and main roof of coal seams, coal fracturing and rocks that contain this coal.

Study of hierarchical structure of fossil coals by small-angle scattering of thermal neutrons

The problem of safety and prevention of sudden gas and rock outbursts during coal mining remains relevant today. One of the factors characterizing the outburst hazard of a coal seam is the structure and petrographic composition of coal. Then we aimed to use small-angle neutron scattering (SANS) to characterize 27 coals to draw relationships between SANS results and seam outburst behavior and other characteristics of coals.Non-destructive method such as SANS of thermal neutrons makes it possible to study the structure in the volume of the samples. Fractal dimensions and their correlation with the specific surface of the pore space, the degree of coalification, the depth of coal-seam and the propensity of the seam to coal-gas-outbursts are determined for coals of the Donets Basin.The outburst hazardous coals were found to have the following characteristics: the surface fractal dimension Ds close to 2.9–3.0 or the mass fractal that are formed by conglomerates of various mineral inclusions containing iron and sulfur. Contrary to this case less outburst-prone coal structure is characterized by more “smooth” pore space surfaces at Ds < 2.9 and by a higher content of silicon and aluminum.

Gasification of pulverized coal in a counterflow moving bed filtration combustion reactor: In search of the optimum

Air-steam gasification of pulverized coal in filtration combustion mode in a moving bed updraft reactor with a counterflow of solid granular heat carrier is considered theoretically. The pulverized coal is supplied to the middle part of the reactor to be mixed and react with the oxidant gas preheated via heat exchange with the solid heat carrier. The parametric domain for major control parameters, which are the air, steam, and the heat carrier supply rates referred to coal flowrate, providing highly efficient gasification conversion with no char in the products is determined using the approximation of thermodynamic equilibrium of products. The procedure for optimization is proposed for a given composition of coal. The excess heat accumulated with the heat carrier provides an opportunity to evaporate water within the reactor; thus, the steam supply can be replaced with a supply of liquid water improving the overall energy efficiency of gasification. This process, as it secures extended residence of gaseous products in a hot reducing environment and an efficient heat recuperation with the solid heat carrier promises a way to combine the merits of entrained-flow gasification (high throughput and tar-free syngas) with the high energy efficiency of counterflow updraft gasification.

Experimental study of the processes of reducing the formation of sulfur oxides during the co-combustion of particles of metalignitous coal and wood processing waste

This paper presents results of experimental research on thermal decomposition processes of a rather common D grade steam coal (metalignitous coal) and wood. The research aims to substantiate the previously formulated hypothesis on the mechanism of sulfur oxide sequestration in the combustion products of such mixtures. The elemental composition of the reference coal and wood biomass (pine sawdust) and the ash remaining after complete thermal decomposition of the studied mixtures was analyzed. The obtained results, along with results of the X-ray phase analysis of the ash composition, showed an increase in the proportion of calcium and aluminum sulfates in solid pyrolysis products. The performed experiments substantiate that the use wood as an additive for mixed metalignitous coal fuels reduces sulfur oxide yield during their combustion in power boilers in large-scale and small-scale power generation systems. It was established that pyrolysis of two-component fuels based on the D grade coal mixed with dispersed wood biomass contributes to reducing sulfur oxide concentration in gaseous products of their thermal decomposition. This effect can be attributed to formation of calcium and aluminum sulfates in the mixed fuel ash. They are formed as a result of reactions between the coal and wood pyrolysis products that occur if the content of wood components in the mixture is from 10% to 50%.

Investigation on the Structure and Fractal Characteristics of Nanopores in High-Rank Coal: Implications for the Methane Adsorption Capacity.

The structure and fractal characteristics of nanopores of high-rank coal were investigated using an approach that integrates N₂ adsorption and field emission scanning electron microscopy (FE-SEM). The results indicated that the high-rank coal of the Shanxi Formation has a complex pore-fracture network composed of organic matter pores, mineral-related pores, and microfractures. The pore type of high-rank coal tends to be complicated, and the main pore types are inkbottle pores and open pores, which are more conducive to methane enrichment. The Ro,max has a negative relationship with the total pore volume. In addition, the ash and inertinite contents show a positive correlation with the average pore size (APS), while the fixed carbon content exhibits a negative relationship with the APS. The pore structure of high-rank coal is controlled not only by the degree of metamorphism but also by coal composition, which leads to the variation in pore structure becoming more complicated. With the increase in coal metamorphism, high-rank coal with high amounts of fixed carbon content generally possesses a higher irregularity in pore structure. No obvious relationship was observed between D₂ and the coal components, which indicates that the pore structure, ash content, moisture content and other factors controlled by the metamorphism of coal have different effects on D₂ that lead to this inapparent relationship. A negative relationship exists between adsorption volume and D1, which indicates that the high irregularity of the pore structure is not conducive to methane absorption and that no obvious correlation exists between the adsorption volume and D₂. In the high-rank coal, the high D1 value represents the complexity and heterogeneity of the pore structure and represents a low adsorption affinity for methane molecules; in addition, D₂ has no effect on the methane adsorption capacity.

Analysis of Leakage and Corrosion of Air Preheater in Coal-Fired Power Plant

A unit of a coal-fired power plant (300MW) in North China was selected to study. The flue gas parameters (NH3, O2 and flue gas temperature) at the outlet of denitration system, oxygen content at the inlet and outlet of air preheater, and composition of combustion coal were tested. Then, the air leakage and corrosion of air preheater were evaluated from the operation of denitration system, air preheater leakage detection, and acid dew point calculation of flue gas. The influence of ammonium hydrogen sulfate from denitration system on the downstream air preheater is limited due to the low ammonia escaping. The air leakage rates of the air preheater at the side A and B were 8.45% and 3.01%, which are higher than the normal value (< 3%). Due to the air leakage of air preheater on side B, the cold end temperature of air preheater is significantly lower than the acid dew point of flue gas, resulting in the condensation of sulfuric acid mist in flue gas on the air preheater and the sulfuric acid corrosion on the air preheater.

ФОРМЫ НАХОЖДЕНИЯ И УСЛОВИЯ ПЕРЕНОСА РУДНЫХ КОМПОНЕНТОВ В БУРЫЕ УГЛИ В ЗОНАХ КОНТРАСТНЫХ ФОРМ СОПРЯЖЕНИЯ ОСАДОЧНЫХ БАССЕЙНОВ И ГОРНО-СКЛАДЧАТЫХ СООРУЖЕНИЙ (НА ПРИМЕРЕ ЗЕЙСКО-БУРЕИНСКОГО БАССЕЙНА И ТУРАНСКОГО МАССИВА) (ДАЛЬНИЙ ВОСТОК, РОССИЯ)

The conditions for the formation of Paleogene-Neogene metalliferous coals in a setting of tectonic movement intensification in the zone of junction between the Turan massif and Zeya-Bureya basin have been studied. The massif with the Selemdzha-Tomsk and Arkhara grabens separated by the Bureya horst and bounded by the systems of northeastern strike-slip faults was found to have a keyboard structure. The research showed that the most favorable conditions for the ore microcomponent accumulation in coals through the erosion of the Late Cretaceous ore-bearing chemical residue were within the submerged blocks of the massif. The paleodrainage system carrying microcomponents drained the grabens and the associated sedimentary sub-basins of the Zeya-Bureya basin eastern margin. Ore components were transported mainly in solution and as solid clasts to the areas of coal accumulation as evidenced by the resemblance of the elementary composition of coals in the Zeya-Bureya basin and geochemical anomalies of the Turan massif.

ВПЛИВ РЕЗУЛЬТАТІВ АНАЛІЗУ АНАЛІТИЧНИХ ПРОБ ВУГІЛЛЯ НА ТОЧНІСТЬ ПРОГНОЗУ НЕБЕЗПЕЧНИХ ВЛАСТИВОСТЕЙ ШАХТОПЛАСТІВ

Purpose: to establish possible quantitative errors in determining the values of some indicators of the degree of metamorphism without attracting the content of total moisture and mineral impurities to predict the hazardous properties of coal mine layers during mining. Methodology: based on the use of initial data on the quality indicators and properties of coals for specific coal seams, given in the reference sources, with the subsequent recalculation of the state of samples from their dry ashless or ashless state to the raw state. Comparison of the samples of indicators were determined, respectively, using analytical samples and based on the results of recalculation to the initial state (close to the production state), conclusions were drawn about possible errors in the case of using the analysis results of the analytical samples to predict hazardous properties of mines. Results: The analytical state of the samples for dry ashless state (daf) or wet ashless state (af) does not correspond to the state of coal in the working area of mining operations (r), which most accurately characterizes the manifestation of mine hazardous properties. The indicators of the release of volatile substances during thermal decomposition of coals, which are used to predict the hazardous properties of mine coal seams, do not directly reflect changes in the elemental composition of coals during metamorphic transformations. Methods for preparing analytical samples provide for grinding to small fractions, removing external moisture and enriching to ash content less than 10%, which does not correspond to the state of coal (r) in the mining area. The use of indicators set for dry ashless combustible (organic) mass excludes the possibility of analyzing the influence of moisture and mineral impurities on the manifestation of the hazardous properties of coal seams. The use of such indicators to predict the hazardous properties of mine coal seams can lead to errors in their determination of 45 ÷ 50%. The hazardous properties of coal seams can be adequately characterized only by the combined composition and properties of organic matter and mineral impurities in a state close to the presence of coal in the mining area. Using the example of possible significant errors in the calorific value, in the case of its use to characterize the hazardous properties of coal mine seams, the expediency of scientific substantiation of a set of indicators for a reliable forecast of a specific hazardous property for a specific seam formation was proved. Scientific novelty: hazardous properties of coal seams are reliably predicted on the basis of the composition and properties of organic and mineral components, reduced to conditions close to the state during mining operations. Practical value: the results obtained give grounds to scientifically substantiate the selection of the necessary indicators for predicting a specific hazardous property of coal seams and make proposals for improving the regulatory framework for the safe conduct of mining operations.

ТЕПЛОИЗОЛЯЦИОННЫЙ МАТЕРИАЛ НА ОСНОВЕ ОСТАТКОВ ПИРОЛИЗА УГЛЯ И ОТХОДОВ СТЕКЛА

In recent decades, materials with high thermal resistance, refractory, non-toxic, with high mechanical characteristics, durable, affordable easy-to-install thermal insulation materials are of great interest. Durability of available thermal insulating materials, for example cotton insulators is from 10 to 20 years, foam is from 7 to 10 years. During burning process of foam plastics, high-toxic material called phosgene is released. At the same time, fungus forms during the process, and it has adhesion incompatibility with cement. Mineral wool decomposes over time, turning into powder, and the installation of external thermal insulation materials in buildings requires surface finishing to protect it from direct weathering, which incurs additional costs. Recently, composite glasses, glass-crystalline materials synthesized from slag-ash wastes of rocks are in great demand. The goal of this research is to study coal and solid waste of coal pyrolysis as a raw material for the foam glass production. In this work, the chemical, phase and mineralogical composition of coal from the Magavuz deposit in the Republic of Artsakh and solid residues of its catalytic pyrolysis have been studied by the modern methods of analysis. Based on the results, a heat-insulating material has been developed, in which pyrolysis waste also plays the role of a gas generator. The selected heat treatment mode ensures the production of heat-insulating foam with high porosity, uniformly distributed in the volume, with sufficient mechanical properties.

ПРИМЕНЕНИЕ НЕОРГАНИЧЕСКИХ РЕАГЕНТОВ-МОДИФИКАТОРОВ ДЛЯ ИЗВЛЕЧЕНИЯ СЕРОСОДЕРЖАЩИХ ПРИМЕСЕЙ ПРИ ФЛОТАЦИИ ГАЗОВЫХ УГЛЕЙ

The relevance of the research lies in the need to remove sulphur-containing compounds from coal raw materials at the lowest cost to reduce the environmental load in the areas of coal use. The object of the study is coals of the “G” brand of the Kuznetsk basin of the Kirov mine. The subject of the study is the petrographic and chemical composition of coals, the content of sulphur impurities. The aim of the study is to develop selective reagent flotation modes using inorganic reagents-modifiers. Research objectives: – to determine the petrographic and chemical composition of coals; – to conduct flotation studies using the foam flotation method; – to evaluate the effect of inorganic reagents-modifiers on the φ - potential and hydration of the coal surface; – to determine the mechanism of modifiers’ action on the depression of sulphur-containing impurities of coals. Methodology and methods of research. A complex of physical, chemical and physico-chemical research methods has been used in the work. The degree of scientific development of the topic. A promising direction for reducing sulphur-containing emissions is to increase the selectivity of the flotation process by modifying the coal surface. Results: petrographic analysis of the studied coals has showed that the main micro-component is vitrinite (85 %); chemical analysis indicates that the humidity of the coals is 2.27 %, the ash content is 17.82 %, the yield of volatile substances is 32.90 %, the mass fraction of inorganic sulphur is 0.38 %, organic sulphur is 0.43 %. A comparative analysis of qualitative and quantitative indicators of coal flotation shows that the use of non-organic reagents-modifiers can significantly increase the extraction of sulfur into flotation waste. The analysis of the kinetics of changes in the electrode potential of pyrite indicates an increase in the potential values in the presence of these reagents and a decrease in the hydration of the pyrite surface. The obtained results indicate the expediency of using inorganic salts as modifier reagents that contribute to reducing the sulfur content in coal concentrates due to the depression of pyrite-containing impurities due to an increase in the hydration of their surface