The paper presents the results of petrographic analysis of five samples of brown coals from the following deposits: Itatskoye, Munayskoye, Arkharo-Boguchanskoye, Kangalasskoye, Baganuur (Mongolia). It was found that the brown coal sample from the Itatskoye deposit (Ro, r = 0.388%) has the lowest vitrinite reflectance, while the brown coal from the Kangalasskoye deposit has the highest reflectance value (Ro, r = 0.490%). An increase in the genetic maturity of the studied samples is associated with a change in the technological properties of their organic matter. It is shown that with an increase in Ro, r, the carbon content (Cdaf) increases, the yield of volatiles decreases, as well as the atomic ratio of H/C and O/C. Visual analysis of polished sections made it possible to determine the maceral composition of the studied coals. The sample of brown coal from the Baganuur deposit (Mongolia) has the highest inertinite content (more than 60%), the sample of the Kangalasskoye deposit contains the largest amount of vitrinite group macerals (86%).
The article presents the results of a study of the influence of ash content of coal on the qualitative characteristics of their IR spectra. Comparative analysis of the IR spectra of the initial and demineralized bituminous coals showed that the mineral components present in their composition in the form of silicates, clay minerals, and carbonates limit the resolution of the method in the range <970 cm-1, since their characteristic peaks are superimposed on the lines from organic matter of coal. Treatment of coals with mineral acids leads to a decrease in their ash content by 5-8 times, which results in an increase in the content of conventional organic matter in demineralized samples. This, in turn, leads to an increase in the optical density of absorption bands in the entire range of the study and, therefore, allows them to be identified more reliably.
The purpose of burning any fuel is to obtain thermal energy, the amount of which is judged by the heat of combustion, their most important thermophysical characteristic. In the modern world, the use of coal as a fuel for the production of heat and electricity leads in terms of consumption. This paper presents the results of measuring the highest heat of combustion of coal in a calorimeter unit. The analysis of the data obtained showed that the value of the highest calorific value depends on the metamorphism stage of coals and their elemental composition.
In this work, the objects of the study were CWC coals (coking weakly caking coals). The samples were characterized by technical analysis, which showed that the coals are close in ash content (Ad = 3.4-8.4%) and the yield of volatiles (Vdaf = 18.4-21.4%). Petrographic analysis determined the vitrinite reflection index (Ro, r), which showed that the studied coals, according to the genetic classification, belong to the 11-13 class, corresponding to the CWC grade coals. Based on the vitrinite reflectance index, reflectograms were compiled, which are an effective means of assessing the quality of coal.
Coals are heterogeneous in nature, and they most often combine different amounts of three macerals-vitrinite, liptinite and inerinite. Vitrinite, which is responsible for the caking capacity of coal, solubility in organic solvents, mechanical properties, etc., is of decisive importance for the technological properties of coal raw materials. This paper presents the results of a study of vitrinite concentrates isolated from coal of the Kuznetsk coal basin. Using chemical and physicochemical methods of analysis (technical and elemental analyses, IR and 13C NMR spectroscopy, etc.), analytical data were obtained reflecting the change in the composition of their organic mass from the degree of coalification. It was found that with an increase in the stage of metamorphism in vitrinite concentrates, the yield of volatile substances (Vdaf) decreases, the carbon content increases from 82.2 to 88.5% and, accordingly, the content of oxygen and heteroatoms in the organic mass decreases from 11.8 to 6.2%.
The paper presents the results of a study of changes in the textural and physicochemical properties of the carbon sorbent surface after oxidative modification with an ozone-oxygen mixture. For the study, we used a carbon sorbent sample obtained on the basis of long-flame coal. It is shown that oxidative modification with the mixture leads to an increase in the surface area of the studied sorbent, mainly due to the growth of micro-and mesopores. In this case, according to IR spectroscopy data, an increase in the content of oxygen-containing groups on its surface is observed.
The results of a study of the chemical and technological properties of low-metamorphosed coals of the Kuznetsk basin of long-flame (L), long-flame-gas (LG) and gas (G) technological grades. Coal samples are low-sulfur, medium-ash with a low ash basicity index, are characterized by a rather significant yield of semi-coking resin, gaseous and volatile substances. According to the established technological indicators, these coals can be recommended for energy and technological use, for example, in the process of semi-coking.
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