Coke and Chemistry最新文献

Germanium is industrially important and has many applications. It is used to produce semiconductors, solar panels, optical fibers, infrared optical systems, catalysts for the production of plastics, and fluorescent coatings. Applications have also been developed in medicine, animal husbandry, and crop production. The great demand for germanium has prompted shortages and price rises around the world and, in particular, in Russia. Fossil fuels are potential sources of germanium. Research shows that industrially significant quantities of germanium are present in Donetsk Basin coal. In coal processing—notably in coking—some of the germanium passes to the production wastes, such as supernatant liquid. With a suitable technology for the recovery of germanium from production wastes, Donetsk Basin coal could be an important source of this valuable element. While such technologies already exist, further research would improve their efficiency.

A comprehensive investigation on the impact mechanisms of biomass blending on coke microstructure and properties was conducted through multi-scale characterization approaches, including X-ray diffraction (XRD), Raman spectroscopy, nitrogen adsorption porosimetry, and scanning electron microscopy (SEM). The results indicate that the introduction of biomass significantly reduces the graphitization degree of coke, as evidenced by the decrease in crystallite size, the increase in interlayer spacing (d₀₀₂), and the reduction in aromaticity. Raman spectroscopy analysis further confirms that, with the increase in biomass addition, the I_D/I_G value decreases by 0.15–0.25, indicating a reduction in aromatic hydrocarbons with more than 6 fused rings. Meanwhile, the I_D/(I_GR + I_VL + I_VR) value decreases by 0.3–0.5, suggesting an increase of 15–25% in the proportion of small aromatic systems with 3–5 rings. The impact of different biomasses varies significantly: Poplar leaves, due to their high volatile matter content, exhibit the strongest inhibition of thermal polycondensation. In contrast, bamboo maintains a more ordered structure owing to the supporting effect of its silicon-aluminum framework. Pore analysis indicates that the specific surface area of biomass char increased from 1.5956 m² g^–1 without the addition of biomass to 2.0462–2.5356 m² g^–1 with the addition of 8% biomass, while the average pore diameter expanded from 4.1459 to 7.4969–9.5383 nm. SEM observations indicate that poplar leaf coke exhibits the highest porosity but also the greatest structural disorder. In contrast, bamboo coke demonstrates the best mesopore connectivity. This study provides theoretical support for optimizing the performance of metallurgical coke through biomass modification.

The heat produced by coke oven gas (COG) accounts for 36% of total heat of coke oven, indicating a significant potential for heat recovery. To effectively recover this heat, a jacket-type heat exchanger was installed at the coke oven ascension pipe. This study uses Fluent software to simulate the jacket-type heat exchanger and determine the impact of the number and direction of the heat exchanger’s inlets and outlets on heat transfer. The results show that increasing the number of water jacket inlet and outlet pipes improves the uniformity of temperature, pressure, and flow field distribution on the water jacket side, but increasing the number of inlet pipes reduces the Nusselt number on the water jacket side by 3%. Changing the direction of the water jacket inlets and outlets at the riser, with tangential inlets, improves the uniformity of the temperature and flow field distribution on the water jacket side, with minimal effect on pressure distribution and a slight impact on the temperature and pressure distribution on the coke oven gas side. A double-inlet double-outlet configuration with tangential inlets and outlets results in relatively uniform temperature, pressure, and flow field distribution within the heat exchanger, making it an ideal model for a jacket-type heat exchanger. These findings are valuable for understanding the heat transfer characteristics of jacket-type coke oven ascension pipe heat exchangers and have important guiding significance for the design of such heat exchangers.

The electrical resistivity of the following solid carbon-based reducing agents is compared: charcoal, petroleum coke, rexil special coke, KhMI special coke (developed at Abishev Chemical and Metallurgical Institute, Karaganda), and blast furnace coke. The goal is to better understand the factors affecting the performance of carbon-based reducing agents in electrofurnace heating. At the temperature used in electrofurnace production of technical-grade silicon (~1600°C), rexil produced from long-flame Shubarkol coal has the greatest electrical resistivity.

The coal market and its prospects are analyzed, with a focus on the use of lignite at thermal power stations. Switching to lignite—on account of economic factors and the exhaustion of other coal supplies—lowers the efficiency of power station equipment and increases operating costs. Slagging, corrosion, and buildup at the heating surfaces in lignite combustion cause problems. The effects of nonuniform radiant flux distribution in the boiler are considered. Methods of reducing the emissions of sulfur and nitrogen oxides are studied: for example, the injection of drying gases; swirling combustion; and stepwise fuel supply. Proposals are made for upgrading the boiler systems, including reconstruction of the burners and convective heating surfaces. Technologies for fuel preparation and cleaning the heating surfaces are noted. Particular attention is paid to slagging and its dependence on the coal composition. The conclusion is that an integrated approach to lignite combustion is needed, including modernization of the equipment, the development of new technologies, and optimization of the operating conditions so as to ensure safe and effective lignite combustion.

With the increasing shortage of high-quality coking coal resources, the efficient and clean utilization of high-sulfur coking coal has become an important research direction in the field of coal chemical industry. At the same time, the environmental problems caused by traditional plastic treatment methods (such as landfill and incineration) have become increasingly prominent. Therefore, in this study, hydrogen-rich plastic polypropylene (PP) was proposed as a hydrogen donor to co-pyrolysis with high-sulfur coking coal. The effects of coal characteristics and mixing ratio on pyrolysis weight loss characteristics and kinetic parameters were systematically studied by thermogravimetric experiment. The results show that the main pyrolysis weight loss temperature ranges of coal and polypropylene overlap significantly, which provides favorable conditions for the interaction between the two. Moreover, there is a significant deviation between the actual weight loss and the theoretical calculation value in the co-pyrolysis process. This phenomenon indicates that the hydrogen-rich components and active free radicals produced by PP during pyrolysis can interact with coal, and there is a significant synergistic effect between the two. Through kinetic analysis, the kinetic mechanism functions of single coal and mixture at different pyrolysis stages were determined. The addition of polypropylene made the temperature range of the second pyrolysis zone significantly narrower and the activation energy increased, but the activation energy of the third pyrolysis zone decreased. This finding not only verifies the synergistic effect again, but also provides an important basis for further understanding the co-pyrolysis mechanism of coal and plastic.

With the increasing shortage of high-quality coking coal resources, the efficient conversion and utilization of high-sulfur coking coal has become the focus of current research. At the same time, traditional plastic waste treatment methods are facing severe environmental challenges. In this study, the migration and transformation of morphological sulfur and its structural evolution of semi-coke during the co-pyrolysis of polypropylene (PP) and high-sulfur coking coal were investigated by simulated coking experiments. X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy (Raman) were used to systematically analyze the effect of PP on the sulfur migration and transformation and carbon structure order of semi-coke. The experimental results show that the introduction of PP significantly changes the pyrolysis characteristics of coal. On the one hand, PP reduces the bond property of coal, which is manifested by the decrease of bond index (G) and the maximum thickness of glial layer (Y), and leads to the decrease of semi-coke yield. On the other hand, Raman spectroscopy analysis showed that the I_D/I_G ratio of the co-pyrolysis product semi-coke increased, while the full width at half maximum (FWHM-G) of the G peak decreased, confirming that the addition of PP made the semi-coke carbon structure tend to be disordered. More importantly, the addition of PP did not show a single promotion effect on the sulfur change behavior during the pyrolysis of JM and FM. With the increase of PP addition ratio, the desulfurization of semi-coke increased first and then decreased. XPS analysis reveals that PP has a regulatory effect on the sulfur migration path: during the co-pyrolysis process, PP promotes the formation of sulfides and reduces the proportion of thiophene sulfur. This finding provides a new theoretical basis for the clean utilization of high-sulfur coal.

By electron paramagnetic resonance (EPR) spectroscopy, the influence of the particle size of unoxidized KS coal on the EPR spectra is investigated. For all the size fractions considered, the EPR spectrum is a singlet. It consists of a broad line described by a Gaussian function; and a narrow line described by a Lorentzian function. The particle size significantly affects the shape of the spectral lines. The 0.1–0.2 mm size fraction is optimal for studying Russian coal by EPR spectroscopy. For this fraction, the difference in width of the EPR lines described by the Gaussian and Lorentzian functions is greatest.

Research on coal samples from the Kolchugino series in the Baidaevsk and Belovsk regions of the Kuznetsk Basin confirms that the degree of reduction of coal samples may be quantitatively estimated by reflectogram analysis and the clinkering and coking properties of coal samples with similar technical and petrographic characteristics may be assessed by the same method. This method was developed by VUKhIN specialists for the analysis of very similar coal samples (coal twins) and assessment of batch quality in coke production. It is effective and simple to use.

This study adopted the tube-in-tube method combined with infrared thermometer to conduct online continuous temperature measurement on a 7.63 m coke oven. The system obtained key thermal parameters such as the center temperature of the coke cake, the lateral temperature, the temperature of the top space of the oven, and the temperature of the raw gas. Based on material balance and heat balance calculations, the thermal efficiency and heat consumption of the coke oven were evaluated, and the heat distribution and operation status of the coke oven were analyzed in depth. The research results indicated that there is still some room for optimization in terms of uniformity of heating, combustion efficiency, and heat loss of the coke oven. In response to potential problems, corresponding optimization and improvement suggestions were proposed to improve the thermal efficiency of the coke oven, reduce energy consumption, and ultimately achieve the goals of energy conservation and emission reduction and ultimate energy efficiency. This research provided data support and technical references for the refined management and energy efficiency improvement of large coke ovens.