Coal-enrichment Wastes 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.

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.

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.

On the issue of wastewater treatment with an organomineral sorbent obtained by electroplasmic processing of coal flotation tailings

The article considers the technology of obtaining organomineral sorbents with a highly developed porous structure from the waste of coal enrichment – carbon flotation tailings. The synthesis of sorbents was carried out using electric arc plasma with the development of a technique for obtaining combined sorbents used for wastewater treatment. The article presents data on the study of functional groups of coal-sludge raw materials to establish the composition and structure of the surface layer with the identification of the nature of surface compounds. The article also discusses a series of laboratory and industrial tests of the sorption-filtering properties of the obtained organomineral sorbents in wastewater treatment and water treatment.

Recycling of waste of coal enrichment and inter-shale clay used for producing ceramic bricks

The research purpose is to produce ceramic bricks using intershale clay as a clay binder and coal preparation waste as a lean and burnable additive without the use of traditional raw materials. According to the environmental monitoring of segments of the fuel and energy industry, including the adjacent territories, the level of environmental pollution was high even in specially protected areas. Efficient disposal of largetonnage fuel and energy waste is one of the urgent environmental problems. The industry that produces ceramic materials for the construction industry has unlimited possibilities for using large-tonnage waste. Since natural raw materials are depleted, the production of ceramic bricks requires the use of waste coal and intershale clay. The costs of geological exploration, construction and operation of quarries are excluded, signifi cant land plots are freed from the impact of negative technogenic factors. The use of interslate clay and coal preparation waste in the production of ceramic bricks makes it possible to obtain products with thermal conductivity and density, less than 0.250 W/(m ºС) and less than 1300 kg/m3, respectively. The use of largetonnage waste from the fuel and energy industry contributes to the environmental protection and expansion of the raw material base of building materials.

Influence of preparation and combustion parameters of coal-water slurries on gas emission chemistry.

The article presents the results of experimental studies performed for the comparative analysis of factors affecting the concentration of the main gas emissions during the combustion of fuel suspensions obtained from coal enrichment waste. The factors influencing the formation of anthropogenic emissions during the flaring of coal-water fuel suspensions were investigated. Experiments were carried out with coal processing waste, both with and without additives in the form of spent mineral oil. The article shows how the concentration of sulfur dioxide, nitrogen dioxide, and hydrocarbons is affected by the parameters of preparation (particle size, solid-liquid phase ratio, additives of used engine oil) and flame combustion (temperature in the combustion chamber, excess air coefficient, and droplet size after spraying) of fuel suspensions. The ranges of parameters were selected at which the best combustion parameters are observed, based on the data obtained: degree of grinding is less than 100μm, solid part content in the suspension is from 55 to 60%; combustion temperature is in the range from 950 to 1050° C, droplet size when spraying the suspension is less than 300μm, additive of waste mineral oil is from 3 to 7 wt.%. and air-fuel ratio from 1.2 to 1.3.

Finding the Specific Surface Area of an Organomineral Sorbent Produced by Electroplasma Treatment of Coal Flotation Waste

This paper dwells upon finding the specific surface area of cake, a coal enrichment waste, exposed to electroplasma treatment; the goal is to make an organomineral porous material to be used as a sorbent for wastewater treatment. The research team used a monomolecular Langmuir adsorption model and surface tension of the surfactants before and after adsorption at the interface of solution and solid adsorbent. Another process considered herein was thermal activation of substances in the electroplasmic reactor for making organomineral porous materials from coal cakes. The paper presents the resulting specific surfaces area of the organomineral sorbent thus produced. Thus, the waste of flotation, i.e. coal cake, is fundamentally suitable for making porous substances by thermal destruction in an electroplasma reactor.

Analysis of the influence of the size of particles on the choice of design and mode parameters of the vibro-impact screen during dehydration and separation of materials

The article is aimed at the development of new methods of separation by size and dehydration of technogenic raw materials during vibro-impact screening. About 1 billion tons of coal enrichment waste with high coal content (25-70%) with up to 45% humidity have been accumulated in ash dumps and sludge settlers of Ukraine. A useful component can be removed from such waste. But traditional methods allow you to effectively separate only materials with particle sizes greater than 1 mm, and reduce the humidity of the finished product to 18-22% depending on the size The reasons for the decrease in the efficiency of these processes with a decrease in the particle size of the raw materials are analyzed. The conditions for increasing the intensification of these processes for raw materials of various sizes have been determined. The author analyzes the effect of particle size on the choice of mode and design parameters of a vibroimpact screen, which make it possible to intensify the loosening of raw materials and thereby increase the efficiency of separation by size and dehydration. Research data on dehydration and separation of materials with a size of + 0.4-1.0 mm are presented; + 0-0.4 mm and + 0-10.0 mm, where the average values of the results of five experiments in each mode are given. The proposed new method of vibroimpact screening is especially useful in the processing of technogenic raw materials of a wide range of sizes, when it is necessary to separate thin classes (as a rule, substandard product) and to dehydrate the finished (oversize) product as much as possible. The use of this method will increase the yield undersize product (-0.1 mm) to 75-80%, and reduce the humidity of the positive product to 4-7% As a result of the analysis for different classes of size the conditions provided are determined under which the maximum decrease in humidity and increase of minus product output is provided. The results obtained will be used to improve the process of separation by size and dehydration of technogenic raw materials, as well as to create a new vibro-impact screen.

New data about the distribution of nickel, lead and chromium in the coal seams of the DonetskMakiivka geological and industrial district of the Donbas

A modern and scientifically based indicators forecast of toxic and potentially toxic element concentrations allows us to develop and plan organizational and technicaltechnological measures aimed at reducing the negative 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 features of the distribution of toxic and potentially toxic elements, including nickel, lead and chromium in coal and the rocks that contain it. Toxic elements are one of the main sources of environmental pollution thatnegatively affects human health. Research in this direction is conducted to reduce the degree of negative effects and additional pollution of the environment. Increasing requirements for environmental protection in the coal-mining industry sector of Ukraine stipulates the need for new scientifically grounded methods for forecasting the content of toxic and potentially toxic elements in the rock mass which is extracted by mines, the waste of coal extraction and coal enrichment and also the influence of the coal-heating enterprises on the environment. In the article, the results of investigations of toxic elements in coal seams of the Donetsk-Makiivka geological and industrial area of the Donbas are considered. The research covered the whole territory of one of the most studied geological and industrial districts of the Donbas – Donetsk-Makiivka. As a result of the study, correlation coefficients were calculated that allow us to predict the concentration of nickel, lead and chromium in the products and wastes of coal enrichment and correct the technological schemes of coal enrichment taking into account their content. We also calculated the regression equation between these elements and the ash content of the coal, which will allow us to predict their concentration in the main working coal seams of the DonetskMakiivka geological and industrial districts relative to the values of coal ash content. The character of the distribution is established and the weighted average concentrations and basic descriptive statistics for nickel, lead, and chromium in the coal seams and suites are calculated. The composition and character of their typomorphic geochemical associations, as well as the features and regularities of their accumulation in the coal seams of the Donetsk-Makiivka geological and industrial districts are revealed.

On the Possibility of Using Fine Coal Waste of the Processing Plant «Energeticheskaya» as a Basis for Boiler Fuel

The article presents the results of experimental tests of the preparation and combustion of CWF obtained on the basis of finely dispersed waste of coal enrichment (filter cake) of the PP «Energeticheskaya» of the branch «Kaltansky Coal Mine» of the Kuzbassrazrezugol Management Company JSC, at the KuzGTU demonstration semi-industrial stand. The tests carried out have shown that on the basis of the RP filter cake, it is possible to prepare a suspension coal-water fuel with structural-rheological and thermophysical characteristics that ensure efficient combustion of the obtained CWF. For fuel combustion, a boiler with a heating capacity of 0.63 MW with a vortex adiabatic furnace was used. The results obtained confirmed the real possibility of industrial use of the developed technology for the utilization of TDOU in the form of VUT at boiler houses, mini-thermal power plants, state district power stations and other heat-generating installations

SOME FEATURES OF BERYLLIUM DISTRIBUTION IN THE K5 COAL SEAM OF THE "KAPITALNA" MINE OF THE KRASNOARMIISKYI GEOLOGICAL AND INDUSTRIAL DISTRICT OF DONBAS

Problem Statement and purpose. For today, to solve environmental problems in the coal mining regions, studies of toxic elements (including beryllium) are obligatory and allow to determine the environmental impact of coal enterprises and coal heating enterprises. The purpose of this work is to establish regularities in the distribution of beryllium in the coal seam k5 of the mine field "Kapitalna".Data & Methods. Using Excel 2016 and Statistica 11.0 at the initial stage of the processing of primary geochemical information, the values of the main descriptive statistics were calculated, building of frequency histograms of the content and the determination of the beryllium distribution law were realized. During evaluating the relationship of beryllium with the organic or mineral part of the coal, the coefficients of affinity with the organic substance were used, which shows the ratio of the content of the elements in the coal with low and high density. Surfer 11 was used in the con­struction of all the maps. During the construction of the maps, graphs and calculation of correlation coefficients, all values of beryllium concentrations and technological parameters of coal were normalized.Results. The results of studies of the spatial distribution of beryllium in the coal bed k5 have been analyzed and areal variations of its concentrations have been established. The influence of variability of beryllium concentrations on the main technological parameters of coal was evaluated. It has been found that with the increase of mineral impurities in the coal seams the concentration of beryllium decreases, therefore, the concentrator of this element is the organic component of coal. The constructed maps are the factual basis for the long-term forecast of the concentrations of beryllium in the rock mass that extract by the mine. The calculated linear regression equations be­tween the beryllium content and the main technological parameters of coal will allow to predict its concentration in the coal seam. These equations can be used for short-term and medium-term forecasting of beryllium content in the extracted rock mass. In its turn, such forecasts should serve as the basis for technological solutions aimed at reducing its content in products and waste of coal enrichment.

Synthesis and optimization of combustion of briquettes based on substandard brown coals of Kazakhstan deposits with multipolymer binders

The work aimed to study the process of burning coal briquettes with polymers. As the object of the research, the coals of Kazakhstan deposits were applied. The methodology of the study included theoretical and computational studies on the applied significance of coal processing, analysis by physicochemical research methods, pressing, drying and briquetting of coal with binders. It is shown that the briquettes combustion takes place stepwise and is characterized by a stationary regime. This is due to the mutual influence of the stages of pyrolysis of polyolefins and combustion of coke residue of substandard coal. In the combustion zone, the temperature did not depend on the content of polyethylene and was 400–500ºC in the coal burnout zone. The optimal compositions of briquettes supporting the combustion temperature of 1300°С were determined: coal-40 %, clay-20 %, polyethylene-40 %. Adding up to 20% clay to the polymer and coal mixture led to the formation of a combustion wave structure with symmetric temperature profiles. Thermogravimetric analysis shows that polyethylene plays the role of the initiator of combustion, burning at 500ºC, and in the future does not affect the maintenance of the combustion temperature of the briquette. The perspective of the results obtained is the possibility of utilization of low-demand coals of various brands of Kazakhstan deposits, which are waste of coal mining and coal enrichment with further production of coal briquettes of the required quality. Coal briquettes made from substandard coals with a multi-polymer binder, from chemical production waste have a higher calorific value, are mechanically robust during prolonged storage, do not crumble in the furnace until complete combustion, and are waterproof. These advantages determine their use for the population, as well as for various purposes of industrial economy, metallurgy and chemical industry.

ТОКСИЧНІ Й ПОТЕНЦІЙНО ТОКСИЧНІ ЕЛЕМЕНТИ У ВУГІЛЛІ ПЛАСТА С8Н ШАХТИ "БЛАГОДАТНА" ПАВЛОГРАДСЬКО-ПЕТРОПАВЛІВСЬКОГО ГЕОЛОГО-ПРОМИСЛОВОГО РАЙОНУ

Toxic elements in coal are one of the main sources of environmental pollution. Their content in coal is quite high, therefore the modern raising of ecological requirements needs taking into account the influence of coal-mining enterprises on state of environment. This causes the need of new scientifically grounded methods for forecasting the content of toxic and potentially toxic elements (TaPTE) in rock mass, as well as in mining waste and coal enrichment. In the article, the results of investigations of TaPTE in coal seam c8H of "Blagodatna" mine field of Pavlohrad-Petropavlivka geological and industrial area of Donbas are considered, for the purpose of establishing regularities in their spatial distribution. The average content and lateral variations of TaPTE concentrations in coal seam were established, maps of the isoconcentrate of TaPTE and maps of the regional constituent of their contents in the area were constructed. The constructed maps are the factual basis for the long-term forecast of the concentrations of TaPTE in the rock mass extracted from mines. Linear regression equations are calculated, they characterize relationship between the concentrations of toxic and potentially toxic elements and the main technological parameters of the investigated layer. These equations can be used for short-term and mediumterm forecasting of TaPTE content in the extracted rock mass. In its turn, such forecasts should serve as the basis for technological solutions aimed at reducing their content in products and waste of coal enrichment. In addition, analysis of the result of statistical processing of geochemical information and geological and structural characteristics of the seam c8H of mine field of "Blagodatna" mine indicates that the formation of the association of Co-Ni-V-Pb-Cr-Mn is associated with the enrichment of contact zones of the coal layer by these elements with thickness of 0,15-0,20 m. The association of Hg and As is due to their genetic connection with the sulfide mineralization of fractured zones of tectonic nature.

Technological directions of coal enrichment waste processing

Technological directions of coal enrichment waste processing

Feasibility studies of the influence of fuels of different composition, including coal-enrichment waste, on the reliability of the boiler operation

The possibility of using waste from coal processing enterprises as an alternative fuel with the simultaneous binding of sulfur oxides in the boiler furnace is considered. A mathematical model of the boiler unit has been developed, with the use of which verification calculations of the boiler were carried out with the determination of the rates of abrasive wear of convective heat exchange surfaces and corrosive wear of the air heater.The dependences of the characteristic parameters of the boiler unit operation on the fuel composition are revealed.Technological and economic assessments of the use of fuels of various compositions, including wastes from coal processing plants and binding components (marble chips), to reduce sulfur oxide emissions are given.

Influence of Organic Matters on the Calcium Carbonate Decarbonization Process

Pure calcium carbonate, chalk, and coal wastes are taken as starting materials. The Gibbs energy of calcium carbonate decarbonization reactions is calculated. By the method of thermodynamic analysis, the effect of carbon and its gasification products on the calcium carbonate decarbonization process is investigated. The intensifying effect of organic matter during heat treatment of calcium carbonate is shown. In addition to carbon, the decarbonization reactions are influenced by gases evolved as a result of the gasification of the organic part of the coal waste. It is theoretically proven that the organic component of coal waste contributes to lowering the temperature of the onset and end of the decomposition of calcium carbonate. To confirm the theoretical background, experimental studies of the behavior of mixtures during heating have been carried out. The effect of organic matter on decarbonization of pure calcium carbonate and chalk has been studied. Thermograms have shown that less caloric energy is required for the decarbonization of chalk than for the decarbonization of pure CaCO3. Organic transformations occur in the material layer, which contributes to intensive heat transfer. The products of thermochemical transformations of the organic mass increase the efficiency of the process of decarbonization of calcium carbonate using the waste of coal enrichment in the composition of the raw mix. The organic component of the waste not only reduces the amount of heat energy expended on the endothermic process of calcination, its presence in the raw material mix reduces the temperature of the process of calcination as pure calcium carbonate and chalk.

Thermodynamics of Reactions Taking Place When Roasting Fuel-Containing Charge Consisting of a Carbonate Component and Coal Enrichment Waste

Thermodynamics of Reactions Taking Place When Roasting Fuel-Containing Charge Consisting of a Carbonate Component and Coal Enrichment Waste

OPTIMIZATION OF THE COMPOSITION OF THE RAW MATERIAL MIXTURE OF LOW-TEMPERATURE CEMENT ON THE BASIS OF FUEL-CONTAINING COAL PREPARATION WASTE

The article presents a method for calculating the composition of a two-component raw material mixture for producing lime-clay cement based on fuel-containing technogenic waste - gravitational waste of coal enrichment. A method for determining the optimal ratio of components in the charge, taking into account the calorific properties of the waste, is given. The key parameter, in this case, is the energy efficiency ratio. The purpose of the calculation is to determine the ratio of components in the charge, which ensures maximum economy of process fuel. The results indicate the possibility of complete elimination of process fuel from the production cycle at the steady-state thermal process through the use of coal preparation waste.

OPTIMIZATION OF THE COMPOSITION OF THE RAW MATERIAL MIXTURE OF LOW-TEMPERATURE CEMENT ON THE BASIS OF FUEL-CONTAINING COAL PREPARATION WASTE

The article presents a method for calculating the composition of a two-component raw material mixture for producing lime-clay cement based on fuel-containing technogenic waste - gravitational waste of coal enrichment. A method for determining the optimal ratio of components in the charge, taking into account the calorifi c properties of the waste, is given. The key parameter, in this case, is the energy effi ciency ratio. The purpose of the calculation is to determine the ratio of components in the charge, which ensures maximum economy of process fuel. The results indicate the possibility of complete elimination of process fuel from the production cycle at the steady-state thermal process through the use of coal preparation waste.

Studies to establish the possibility of using coal-enrichment waste as an energy raw material in ceramic technologies

The article presents the results of a study of high-carbon coal-enrichment wastes that to be used in the technology of building ceramics to replace technological fuel at the stage of isothermal excerpt during the firing of semi-finished products. The mineral composition of the waste, the composition of its organic part, thermal and technological properties have been studied. The comparative characteristics of the properties of ceramic materials obtained on the basis of mixtures with the use of clay raw materials and coal waste in different quantities are given. In laboratory conditions, materials were obtained that were heat treated at a temperature of 950 °C under the usual regime and a special regime that simulates self-baking due to the heat of oxidation reactions of the combustible part of the coal waste. The expediency of using special oxidizing agents in the form of a combination of ammonium and calcium nitrate salts, whose function is to create an oxidizing medium in the fired material volume due to the formation of O2, NO2 and N2O oxidizing agents during thermal decomposition, is shown. It is established that the mechanical strength of ceramic samples is only 15 % less than for conventional firing samples and is 8.5 N/mm2 for mass with 22 % of coal waste. Based on the conducted studies, it is shown that it is possible in principle to use a special firing regime without consuming an energy carrier at the stage of excerpt for fuel-containing materials using coal waste as energy raw materials.