Coke and Chemistry最新文献

A strategy is proposed for the synthesis of graphene oxide from an intercalated graphite compound. The intercalated graphite compound is based on stage III graphite nitrate, which is graphite with nitrogen compounds introduced between its planes. The modified Hummers method is used for oxidation of the intercalated graphite compound. The initial material and the products are characterized in detail by physicochemical methods: scanning electron microscopy, Raman spectroscopy, and high-temperature catalytic oxidation. As oxidation of the intercalated graphite compound continues, the defect content of the initial carbon framework increases, on account of decrease in size of the crystallites. Raman spectroscopy indicates that the initial intercalated graphite compound is a graphite structure with few defects of the graphene layers. With oxidation of the sample, the disorder of the carbon framework gradually increases. In part, this is due to shrinkage of the graphite-like crystallites, with subsequent reorientation of the graphene layers. After a certain time, the initial structure is modified: we note partial restoration of the graphite-like fragments and simultaneous proliferation of defects.

The theory, practice, and legal foundations of lending to coal mining organizations are considered in an era when the cost of servicing external debt is rising and the distribution of investment capital within the coal industry is unstable. Economic and legal mechanisms for the regulation of credit to coal-mining enterprises are systematized. Improvements in the relevant regulations are recommended: in particular, closer monitoring of national banks, so as to track the use of funds allocated to mining enterprises for environmental upgrades. The need to develop preferential banking schemes for mining activities is emphasized.

Thermogravimetric analysis is used for preliminary assessment of how ozonation affects the yield of coal tar factions in distillation. Since the distillation temperature of light fractions matches the main peak of gas liberation in coal tar pyrolysis, the yield of tar fractions may be indirectly assessed by means of the intervals corresponding to the boiling points of standard tar fractions: <170°C, light; 170–210°C, phenol; 210–230°C, naphthalene; 230–300°C, absorbing fraction; 300–360°C, anthracene; and 360–1000°C, pitch. Treating tar with ozone in the absence of solvents does not significantly change the yield of the fractions. By contrast, ozonation of coal tar in the presence of benzene and chloroform lowers the yield of fractions boiling below 300°C and significantly increases the mass loss in the temperature ranges corresponding to the anthracene fraction and pitch.

The adsorption kinetics of Mn²⁺ ions by AG-3 activated carbon granules is investigated. It is found that the pseudo–first-order Lagergren kinetic model describes manganese adsorption for only 300 min. By contrast, the pseudo–second-order model proposed by Ho and McKay describes the entire process. The role played by diffusion through the sorbent pores in limiting the rate of Mn²⁺ ion extraction is estimated by the Weber–Morris method, on the basis of the isotherms of Mn²⁺ ion adsorption by activated carbon granules. With a high degree of correlation (R² ~ 0.96–0.99), the equilibrium of Mn²⁺ ion adsorption is described by the Langmuir equation. The limiting adsorption capacity of a sorbent monolayer is calculated at various temperatures. When using the adsorptional equilibrium temperature, the thermodynamic parameters of the process are determined. The sorptional extraction of metal ions is greater at higher temperatures. The adsorption of metal ions at the carbon surface is described by means of IR spectroscopic data.

The following characteristics of molecularly oriented coke domains are investigated as a function of their position within the coke and the distance from the coke oven’s heating wall: their height L_c and width L_a, the interplane distance d₀₀₂, the domain density ρ, and the number of layers N within the domain. It is found that L_c and L_a decrease nonlinearly with increase in the distance from the coke oven’s heating wall. The coke’s structural strength Π_c (State Standard GOST 9521–2017) is greater for positions near the wall than for the central region of the coke. The ash content and chemical composition of coke samples in the >0.1 mm and <0.1 mm size classes are determined after crushing in a mill. On the basis of the results of this research and literature analysis, it is established that there is no reliable mathematical model relating the high-temperature characteristics CRI and CSR with the cold mechanical strength M₁₀ and M₂₅. Hence, in broad coke ovens, with constant batch composition, the coke produced may be regarded as of high quality in terms of M₁₀ and M₂₅ but of low quality in terms of CRI and CSR. If the variation in the characteristics of the molecularly oriented domains and the strength of the coke after reaction with CO₂ (CSR) are compared as a function of the distance from the coke oven’s heating wall, it is clear that the parameters L_c, L_a, and d₀₀₂ may be used to create a model capable of predicting CSR.

The benefits of coke production from low-grade coal by stamp charging of the batch are discussed. The influence of production conditions on the formation of dust fractions (≤0.5 mm) after reaction with carbon dioxide is studied. The quantity of dust fractions formed is linearly related to the coke strength CSR after reaction with carbon dioxide. The batch composition and design features of the coke battery have no significant influence on this relationship. The formation of dust fractions (≤0.5 mm) is 1.68 times greater when using traditional coke in the blast furnace than when using coke produced from stamp-charged batch.

A plasma-chemical method is used to process a mixture of fuel oil and lignite in a system of productivity 1000 kg/h. Mild plasma-chemical processing is associated with considerable cracking of the organic component. Liquid hydrocarbons are produced in ~77% of the theoretical yield. By chromatography and mass spectrometry, the group composition of the liquid product is established. This product boils at temperatures up to 400°C and contains 54% linear paraffins (including 37% solid paraffins), 15% isoparaffins, 4% cyclic paraffins, 4% olefins, and 23% aromatic compounds. The total power consumption in processing 1 t of raw material is ~31 kW (including 6 kW in the operation of the plasma-chemical reactor), disregarding the expenditures in extracting the liquid hydrocarbon fractions and the semicoke from the product.

Coal consumption in heating may be decreased by switching to solid-fuel mixtures. In the present work, the influence of the heating rate on the combustion of coal with paper waste is studied. Mixtures with 25, 50, and 75% waste are considered. By thermal analysis in an oxidative medium with an air flow rate of 50 mL/min, at heating rates of 10, 20, and 30°C/min, the following combustion characteristics are determined: the maximum rate of mass loss and the corresponding temperature; the ignition temperature of the coke residue; the temperature at which combustion ends; the combustion index; and the mean reactivity of the fuel. The results show that, on increasing the heating rate, the temperature range characterized by combustion of volatiles and coke residue is shifted to higher values. The change in the temperature ranges corresponding to different stages of combustion is found to improve mixture combustion even with increase in ignition temperature of the coke residue. Threefold increase in the heating rate increases the combustion index (by 407%), while the mean reactivity increases by 134%. Increase in the mixture’s content of paper waste improves the basic combustion characteristics on account of its high content of volatiles.

Attention focuses on the possibility of automating systems for determining the postreactive strength CSR and reactivity CRI of coke pieces (≥20 mm) in a gaseous medium at 1100°C, with subsequent abrasion testing in a drum. Methods of controlling the coke testing are investigated. Current methods of automation and measurements are analyzed and rated. Promising approaches are outlined. The structure of a practical automation system corresponding to State Standards GOST 32248–2013 and GOST R 54250–2023 (ISO 18894:2018) is described.

The structural features of anthracite are investigated by infrared (IR) and Raman spectroscopy. Three anthracite samples from the Bungursky, Krasnogorsky, and Listvyansky mines are studied. Their vitrinite reflection coefficient varies from 2.58 to 5.26%. Analysis of IR spectroscopic data shows that the anthracite with the largest vitrinite reflection coefficient (the Listvyansky sample) has the greatest aromatic parameters (f_a, AR1, and AR2). Its organic mass contains shorter and more branched aliphatic side chains, as confirmed by the low CH₂/CH₃ ratio. Raman analysis confirms that ordered graphite-like structural fragments predominate in the Listvyansky anthracite