Solid Fuel Chemistry最新文献

To investigate the influence of water content on coal combustion characteristics, bituminous coal was collected as the research target from the Wusitai Coal Mine. The combustion characteristic parameters of coal samples with various water contents were measured by cone calorimeter, and the combustion efficiency of coal samples was analyzed. The spontaneous combustion characteristics of samples are significantly affected by moisture within coal. As the rise of moisture content, the ignition time of bituminous coal is firstly reduced and then it is enhanced. The coal sample with moisture content of 10.36% has the fastest ignition. The total smoke discharge, the peak heat release rate and the flue gas generation rate of bituminous coal samples are firstly decreased, then increased and finally reduced with the increase of water content. In the later stage of combustion, the CO generation rate is the smallest for the bituminous sample with water content of 6.59%, while it is the largest for the sample with 18.78% content of moisture. Large moisture content makes the coal sample incomplete combustion, which can improve the CO production rate. The combustion efficiency of bituminous coal can be improved by the appropriate moisture content. It was found that the total CO generation rate, smoke release rate and the ignition time are effectively reduced, after setting the moisture content of 6.59–10.36% of the coal. As a result, both the combustion efficiency and heat release rate are improved.

In order to effectively prevent and control the gas disaster during the mining of deep coal rock bodies and improve the extraction efficiency, this paper carries out the research on the coal microstructure, gas seepage and the characteristic parameters of the coal rock bodies by means of scanning electron microscopy and low-temperature liquid nitrogen adsorption test, and adopts a combination of numerical simulation and on-site engineering validation to study the stress distribution around the surrounding rock after excavation, the range of fracture zone and plastic zone generated by the coal rock around the drill hole to optimise the design parameters of gas extraction in the mining area, by using FLAC 3D and COMSOL Multiphysics. The stress distribution around the surrounding rock after excavation, and the range of fracture and plasticity zones generated in the coal rock around the drill holes, in order to optimise the design parameters of gas extraction in the mine. The study shows that: with the increasing of lateral pressure coefficient, the stress concentration phenomenon in the roadway evolves into vertical symmetrical distribution, the working face of the test mine coal seam crushing area ranges from 0 to 5m, the coal seam plastic area ranges from 12 to 16 m, the stress concentration area ranges from 8 to 24 m, and the original stress area is after 24 m, and the depth of drilling hole reaches the peak of the stress at 16 m, and the drill cuttings method is adopted on the site to verify the simulation results, and then it is decided to determine the reasonable sealing depth of 2#coal seam in the test mine. After verifying the simulation results by drilling chip volume method on site, it is determined that the reasonable sealing depth of the test mine 2# seam is 16 m.

Gas adsorption capacity of coals is one of basic characteristics of coal. Oxygen adsorbed by coal leads to spontaneous combustion. The adsorption capacities of coal samples from the Karadon Region of Zonguldak were determined for nitrogen, methane and carbon dioxide gases. Gas contents and gas adsorption capacities for Karadon coals were correlated.

China is endowed with abundant coal reserves, yet it remains heavily reliant on oil and natural gas imports. Pyrolysis of coal into gas and oil products presents a promising solution to address China’s energy security concerns. Co-pyrolysis of coal and plastic can enhance the production of liquid and gas products. Thermogravimetric experiments were conducted to explore the effects of mixing ratio, coal type (bituminous and anthracite), and plastic type (polystyrene PS and polyethylene PE) on the co-pyrolysis of coal and plastic. The results showed that the interaction during the co-pyrolysis of coal and plastic occurred mainly in the temperature interval of plastic weight loss and contributed to the increase of pyrolytic conversion. Compared to theoretical calculations, conversion rates of coal/plastic blenders co-pyrolysis can be improved mostly at blending ratios of 50% PS and 75% PE, achieving increases of 7.9–8.9% and 4.2–7.2% for PS/coal and PE/coal at 800°C respectively. The synergistic effect of coal type on co-pyrolysis is influenced by both the blending ratio and the plastic type used. So does plastic type. Finally, the kinetic analysis of co-pyrolysis was carried out. It is found different weight loss stage of co-pyrolysis processes can be expressed by first order reaction.

This article presents the results of studies on the noble metal contents of the Paleozoic dictyonema shales of the Baltic sedimentary basin. On the territory of the studied Kaibolovo–Gostilitsy prospecting area, high, up to potentially industrial, concentrations of noble platinum group metals (PGMs), comparable with the concentrations in sedimentary ore types taken into account by the State Balance of Mineral Reserves of the Russian Federation, have been confirmed with a large factual material (more than 600 shale samples). Increased gold and silver contents have also been noted. Palladium predominated in the composition of platinum group metals. The article presents the identified features of the PGM distribution over the area and in the section of the shale-bearing sedimentary strata. Precious metals in the dictyonema shales of the Baltic basin are distributed in the shales in the following forms: in terrigenous scattered finely dispersed native minerals (forms), in impurities in sulfide minerals (mainly in pyrite), and in species localized in the organic matter (Ag and partly Au). The conditions of formation of precious metal mineralization in the dictyonema shales have been reconstructed. The source of precious metals were rocks of the provenance area—the Baltic Shield—and seawater of the ancient sedimentation area, a supplier of a number of rare metals deposited on the geochemical reducing barrier of the dictyonema shales. Increased and stable concentrations of precious metals in combination with large-scale (billions of tons) geological resources of the dictyonema shales indicated the possible presence of a large unconventional mineral resource base of precious metals in the Baltic region of Russia.

Briquetting is a crucial component of clean coal technology. Pulverized coal from Naomao Lake coal mine in Hami area was selected as experimental sample to investigate the effects of binder and moisture content on briquette quality. The results show that binders can enhance relax density, compressive strength, hydrophobicity and durability. And, binder type has a significant impact on energy consumption during briquetting process. For cement and clay, as addition ratio increases, briquetting energy consumption also increases. For bentonite and sodium humate, addition ratio has a small impact on briquetting energy consumption. In addition, compressive strength, hydrophobicity and durability of briquettes gradually increase with the enhancement of moisture content. Moisture can provide effective lubrication during moulding process, reducing friction between raw materials and between raw materials and mold. Afterward, by using the PCA method, a new comprehensive evaluation index was established to investigate the influence of binder type and binder ratio on the quality characteristics of pulverized coal briquetting. The results show that comprehensive evaluation index of briquettes gradually increases with the enhancement of binder ratio, and the briquette containing 15% sodium humate has the highest comprehensive evaluation index, which confirms the reliability of the proposed evaluation method for briquette quality.

Gas content and spontaneous combustion susceptibility of coals are among the most important issues to be considered in underground coal mining operations in terms of coal characteristics. Coals may have different gas contents capacities and spontaneous combustion tendencies due to differences in their composition, formation stages and environmental impacts. From this point of view, the gas contents of coals with different spontaneous combustion tendencies should also be examined and these parameters should be evaluated together in terms of preventing possible accidents. As emphasized in the literature studies, the tendency of coal to spontaneous combustion starts with oxygen adsorption to the coal and then combustion starts with the heat released. Within the scope of this study, the gas contents of coal samples taken from the Karadon Region of Zonguldak Hardcoal Basin were determined. In the last stage, the spontaneous combustion susceptibility test was carried out on these samples with the crossing point temperature determination method and their spontaneous combustion susceptibilities (ignition point temperatures and FCC spontaneous combustion index values) were determined. In the light of these findings, spontaneous combustion tendencies and gas contents for Karadon coals were correlated with each other.

Spontaneous combustion of coal is one of the important factors affecting coal mine safety. Many coal mine accidents are caused by spontaneous combustion of coal In order to study the influence of particle size on coal oxidation temperature rise, a temperature programmed test system was used to study the gas generation law in oxidation temperature rise of coal samples with different particle sizes in Dongrong Coal Mine. The thermal reaction of five different particle sizes of coal was studied by differential scanning calorimetry in thermal method The results show that the smaller the particle size, the greater the gas release of coal samples; With the decrease of particle size of coal sample, the reaction area between coal sample and oxygen increases, and the cross point temperature corresponds The particle size of coal sample has obvious influence on the tendency of coal spontaneous combustion. It is of practical significance to study the difficulty of coal spontaneous combustion by using activation energy. According to the experimental data, it is necessary to prevent and control coal mine fires.

The article presents the results of a study of the structure of humic acids isolated from brown coals of Yakutia and oxidized coals of Kuzbass using nuclear magnetic resonance spectroscopy and IR spectroscopy. Based on the ¹³C NMR spectra, their structural parameters, such as the aromaticity index and hydrophobicity index, were calculated. It was noted that the humic acids of oxidized coals were characterized by higher values of the aromaticity and hydrophobicity indices than those of the humic acids of brown coals. The results of titrimetric analysis showed that humic acids isolated from oxidized coals were characterized by a higher concentration of carboxyl and carbonyl groups. Based on the study, it was suggested that the humic acids of brown coals from Yakutia will have stronger growth-stimulating properties than the humic acids of oxidized coals from Kuzbass.

Hydrotreatment is a crucial operation in the modern oil refining industry, used for removing heteroatoms and hydrogenating aromatic compounds. Middle distillates of coal tar can serve as an alternative feed for producing diesel fuel after heteroatom reduction. Coal tar was obtained through the pyrolysis of Mongolian brown coal at 700°C. The middle distillate, with a boiling range of 220–350°C, was separated from the tar by vacuum distillation, yielding 36.09 wt.%. Hydrotreatment of the middle distillate was carried out at temperatures of 340 and 360°C using a continuous flow, fixed bed reactor filled with a commercial NiMo/Al₂O₃ catalyst. The hydrogen pressure was 6MPa, and the hydrogen flow rate was 0.54 ml/min. The results showed that decreasing the liquid hourly space velocity (LHSV) from 1.55 to 1.03 h^–1 significantly reduced the content of heteroatoms in products from 6.16 to 2.60% and 4.36 to 0.52% for 340 and 360°C, respectively. The total removal of heteroatomic compounds from the middle distillate was highest at 92.36% for the product obtained at 360°C temperature using LHSV 1.03 h^–1.