Solid Fuel Chemistry最新文献

The samples of humic acids (HAs), hymatomelanic acids (HmAs), humus acids (HuAs), and fulvic acids (FAs) and residual coals were obtained by extraction from brown coals of the Kansk-Achinsk and South Ural coal basins. The fractions of humic substances were studied using Fourier transform IR and ¹³C NMR (CPMAS) spectroscopy, technical analysis, and elemental analysis. It has been established that all fractions of humic substances had individual elemental and structural group compositions.

The re-engineered feedstock technique converts low-quality coal into high-quality coal using physical processing on AFBC boiler under full scale with coal as primary fuel. The physical feedstock mixing was adapted as it is identified as having the potential to improve the quality, environmental impact, and energy efficiency of coal combustion. The addition of 6.3% of limestone significantly reduced the SO₂ emissions by 34% and the structural stability was ensured by the retained Fe. The erosive corrosive studies ensures no degradation to the structural material due to the introduction of the limestone particulates. The reduced concentration of sulphur content in the flue gas and passivation of surfaces with the limestone together synergetically reduced the erosion-corrosion effect on the rifle tube section.

To study the effect of pyrite on coal spontaneous combustion characteristics in low-rank coal under an oxygen atmosphere in goaf, this paper selected PZ brown coal impregnated with pyrite and its reaction products and monitored the changes in the generation of characteristic gases CO and CO₂ during the programmed heating process of coal samples. The experiment found that oxygen concentration has the greatest impact on the spontaneous combustion characteristics of coal with added Fe³⁺. When the oxygen concentration in goaf coal increases to 9%, the promotion rate of high sulfur coal spontaneous combustion is the highest, which easily increases the range of goaf spontaneous combustion risk areas. When the temperature rises to 60°C, the catalytic effect of pyrite reaction products on coal spontaneous combustion is greatly enhanced. Through FTIR testing, it was found that Fe³⁺ ions, as strong oxidative free radicals, promote the reaction of –CH₂–, –COOH, and –OH in coal at low oxygen concentrations, leading to a further increase in the tendency of coal to self ignite at low oxygen concentrations.

A change in the structure of the pyrolytic carbon coating deposited on the surface of a graphite substrate was shown depending on the time the substrate remained in the reaction zone. A multilayer spherical structure of the pyrolytic carbon has been revealed; according to experimental data, is formed on a layer of already formed pyrolytic carbon. A mechanism for the formation of a multilayer spherical structure is proposed.

Results of approbation of the methodology developed at NUST MISIS for assessing the long-term leachability of major and trace elements out of coal mining wastes are presented. This methodology is used to assess the impact of such wastes on the environment when they are placed in dumps or used for reclamation. Three coal mining wastes of various mineral and chemical compositions have been tested. The results have demonstrated that the prolonged treatment of waste with a high sulphur content leads to the oxidation of sulphur-containing compounds, resulting in a significant increase in concentration of water-soluble forms of sulphur, calcium, iron, potassium, sodium and magnesium after the 6th week of treatment, as well as in a decrease in the total sulphur content after the 9th week of processing.

The results of derivatographic studies of the decomposition of oil shale and thermolysis processes in the presence of oil shale are presented. It was found that the addition of oil shale to brown or hard coal intensified the process of thermal dissolution of coal, and the solubility of the organic matter of coal increased with the amount of added oil shale; gas formation decreased and the yield of liquid products increased. The activating role of oil shale was also revealed in the processes of thermolysis of oil residues, gasification (high-temperature thermolysis) of fuel oil and tar emulsions, and preparation of bitumen compositions for road construction.

To study the problem of predicting and preventing high-temperature heat damage in deep mining of mines. The heat exchange and mass exchange algorithms of the ventilation network parting wind and surrounding rock are applied, and the model of the heat exchange coefficient of the wind flow in the drenching tunnel is adopted. TF1M3D simulation platform is developed by the College of Safety Science and Engineering of Liaoning Technical University. It is a dynamic disaster simulation software that visually and dynamically reflects the disaster spread and evolution in the ventilation system during the occurrence of major disasters in mines. Based on the theory of mass-energy active wind network, TF1M3D simulation platform can solve the problems of heat and humidity exchange, heat and mass transfer numerical calculation and so on.@Combined with the engineering example of Daqiang Mine, the algorithm is incorporated into the mine network domain system, and TF1M3D is used on the MATLAB platform to simulate and solve the temperature of the wind flow of the whole mine network domain system, and predict the temperature of the 0306 working face of Daqiang Coal Mine and put forward the simulation program of refrigeration cooling. The simulation results show that the maximum temperature of the future 3106 working face of Daqiang coal mine reaches 34.6°C, and the heat damage problem is serious. In the adopted cooling program, two refrigeration units are preferred to four refrigeration units, and the effective temperature control range of the two 250 kW refrigeration units is from 25 to 305 m, while the cooling meets the temperature of the working face airflow below 30°C. The results show that the method can accurately predict the temperature of the wind flow after cooling and the location of the cooling source, which provides a basis for the scientific development of the cooling program.

The possibility of producing carbon–carbon composites by catalytic chemical vapor deposition has been investigated. Anthracite dust of deposits in the Gorlovskii basin was used as an initial carbon matrix. Salts of nickel acetate and iron oxalate were used to form catalytically active metal particles (nickel and iron) on the surface of anthracite. The precursor salts were supported by an incipient wetness impregnation of anthracite samples with aqueous solutions. Optimal conditions of thermal treatment in inert and reducing media were determined for the used salts. Scanning electron microscopy was used to study the secondary structures of the original anthracite with supported metals and synthesized carbon–carbon composites. Using the low-temperature nitrogen adsorption method, a significant increase in the specific surface area of an anthracite sample with supported nickel as a result of its treatment in an atmosphere of saturated C₂–C₄ hydrocarbons at 600°C was demonstrated.

In this article, we mainly completed the related research on the establishment of organic macromolecular structure model of Taixi anthracite as coal-based activated carbon precursor. The understanding of coal macromolecular structure is of great significance to clean and materialized utilization of coal. In this paper, the aromatic structure, aliphatic structure and heteroatomic structure of Taixi anthracite were characterized by ¹³C-NMR, FTIR and XPS. The macromolecular structure of coal was modeled by linking polycyclic aromatic hydrocarbons through bridging bonds (–CH₂–, –CH–) and attaching oxygen/nitrogen functional groups. The molecular formula was determined to be C₂₂₂H₁₁₉NO₁₁. The ¹³C-NMR simulation curve of the two-dimensional macromolecular model was in good agreement with the experimental curve. Through molecular mechanics (MM) and molecular dynamics (MD) optimization, the bond elastic energy (E_B) and Van der Waals energy (E_VAN) decrease greatly, which mainly lead to the acquisition of the three-dimensional energy minimum conformation. In addition, the density simulation result of 3D structural model with periodic boundary conditions is 1.37 g/cm³. This is close to the measured density, which confirm that the 3D structure is reasonable. The establishment of this model helps to further understand Taixi anthracite, which is beneficial to guide the preparation of activated carbon from Taixi anthracite.

The Tavantolgoi coal deposit used in our study is one of the largest deposits and belongs to coking coal of the Permian age. Technical properties of each layer of coal in Ukhaa Khudag of the Tavantolgoi deposit were determined and compared. This study was carried out by selecting coal from layer 4C, which has the lowest calorific value of economically important layers. Sieve analysis of the coal samples was carried out to select the ultra-fine or ˂0.25 mm particle size fraction, and three different methods of flotation enrichment were conducted and compared. In this, conventional flotation, flotation after interplay of ultrasonic vibration and flotation after interplay combined with ultrasonic with electrolysis were carried out, respectively. As a result of the experiment, the best result was the coal concentrate with 6078k Cal/kg calorific value and 25.65% ash content of flotation after interplay of ultrasonic vibration combined with electrolysis. Therefore, we have determined the suitable experimental conditions for the further application of ultrasonic vibration in combination with electrolysis. We determined that the ultrasonic vibration time of 20 min, the amount of ethanol of 30 ml, and the electrolysis power of 1.5 A are suitable condition because the ash content of the floating concentration is the lowest, 24.1%, and the caloric content was the highest (6264 kcal/kg).