S. M. Kolesnikova

Generation of pitch-like products by the thermal dissolution of coal in heavy semicoking tar

The influence of hydrogenating upgrading of heavy semicoking tar from long-flame coal on its properties and composition is studied when it is used as the solvent in the thermal dissolution of bituminous gas coal (GZh coal). It was found that the concentration of oxygen-bearing compounds declines on catalytic hydrogenation of tar at 5 MPa and on combined treatment with two hydrogen donors: tetralin and the anthracene oil. After hydrogenating treatment, the heavy semicoking tar may be used as the solvent in the thermal dissolution of GZh coal so as to obtain pitch-like products.

Conversion of brown coals in aqueous and toluene-containing media under supercritical conditions in the presence of catalysts

The conversion of brown coals from the Borodino and Kangalas deposits in an aqueous medium and in a mixture of toluene with water was studied under supercritical conditions over the temperature range of 375–550°C and at pressures from 22 to 40 MPa. It was found that the methanation, hydrolysis, and oxidation reactions of brown coals with the predominant formation of gaseous products (methane, carbon dioxide, and hydrogen) prevailed in an aqueous medium. Liquid substances were formed in an insignificant amount. In the toluene solvent under supercritical conditions at 440°C, the addition of a small water amount (15%) stimulated the degradation of coals with the predominant formation of liquid products and moderate gas formation. The use of calcium oxide and sodium hydroxide as catalysts increased the yields of liquid products. It was noted that the reactivity of Kangalas coal in this process was higher than that of Borodino coal.

Structural properties of carbonization products obtained from brown coals with different mineral matter contents

The structural properties of carbonization products obtained from different samples of initial and partially demineralized brown coals from the Borodino, Berezovo, and Kangalas deposits and the Yallourn deposit (Australia) were studied depending on the composition of the mineral matter of coal. Differences in the specific surface areas and the spatial structure characteristics of the organic matter of the test samples were found. It was shown that the carbonization products obtained from coals partially demineralized with the dilute solutions of acids, in comparison with the carbonization products of natural coals, were characterized by a lower concentration of an ordered graphite-like component (60–72% against 74–93%) but a higher degree of its graphitization (0.24–0.52 against 0.20–0.35). The dependence of these properties on the calcium content was revealed.

Composition and reactivity of coal from the Khoot deposit in Mongolia

The composition and reactivity characteristics of Khoot coal from Mongolia in the processes of pyrolysis, gasification, thermal dissolution, and the production of porous materials were determined. It was established that the coal is characterized by high activity in the reactions of destruction. In the process of semicoking, the yield of liquid tar was as high as 10%. Highly porous activated carbons with specific surface areas to 900 m2/g and high sorption capacities were obtained by the steam activation of carbonizates. To 60.8% liquid products at low gas formation can be obtained from the Khoot coal in the process of thermal dissolution in a hydrogen-donor solvent at 450°C without the use of hydrogen.

Temperature Effect on the Thermal Dissolution of Coal

The main process characteristics of the thermal dissolution of grade Zh coal in the anthracene fraction of coking tar depending on temperature and reaction time were determined. It was established that the effective extraction of quinoline-soluble products occurred in a temperature range of coal conversion into a plastic state. The process proceeded selectively; at 350–380°C, the yield of the quinoline-soluble products was 71–75%. In this case, the yield of toluene-soluble products did not exceed 10%, and the yield of gas was 0.5%. At a higher temperature and a long reaction time (>2 h), a sharp decrease in the characteristics of thermal dissolution occurred.

Thermal Dissolution of Coking Coals in the Anthracene Fraction of Coal Tar

The thermal dissolution of two samples of 1GZhR and ZhR coal in the anthracene fraction of coal tar is studied. The yield of quinoline-soluble products increases considerably in the temperature range of coal softening. Optimal thermal-dissolution conditions are determined for selective production of quinoline-soluble pitch-like products. At 350–380°C, the yield of quinoline-soluble products is 70–73% after 1–2 h. The yields of the distillate fraction and the gas are 0.9% and 0.2%, respectively. The ash-free pitch-like product is a plastic mass with a softening temperature of 76–81°C. It consists mainly of polycyclic aromatic hydrocarbons with a few short alkyl substituents in the aromatic rings. The spatial structure mainly includes poorly structured polycyclic aromatic molecules of the γ component. The proportion of relatively ordered graphitelike packets is 31–37%. Each packet contains five stacked polycyclic aromatic molecules of diameter 17 Å. In terms of its composition and plasticity, the product is suitable as a source of alternatives to coal pitch.

Rare and rare-earth elements in the metal-bearing coals of the north of the Lena Coal Basin

The increased metal-bearing capacity of coals from the Salga-Tabakh area in the north of the Lena Basin was established. In terms of the composition of rare-earth elements, they can be attributed to the collectors of the most expensive yttrium group. A process flowsheet was proposed for the extraction of rare-earth elements from coal ashes; this flowsheet can be used both independently and as a part of coal conversion processes with the production of liquid fuels and other valuable chemical products.

Steam gasification of Mongolian coals

The composition and thermal properties of brown and black coals from a number of deposits in Mongolia were determined. Their reactivity in the process of steam gasification was studied. It was found that semicokes obtained from coals of the Baganuur, Khovil, Shivee Ovoo, and Bagakhangai exhibited comparatively high reactivity in this process. Deep conversion into combustible hydrogen-containing gas was achieved at a temperature of 750°C. As compared with the Mongolian coals, carbonization products from the brown coal of the Borodino deposit in the Kansk-Achinsk Basin exhibited increased gasification activity, which is related to the presence of a considerable amount of calcium compounds in its composition; these calcium compounds render catalytic action on the interaction of carbon with water vapor.

Hydrogenation of coal from the Chaidakh deposit in the Lena Basin

The results of the evaluation of coal from the Chaidakh deposit in the Lena Basin as a raw material for the production of liquid fuel by hydrogenation are reported. Coals from the Chaidakh deposit, whose reserves exceed 250 million tons, have favorable mining and geological positions and low ash and sulfur contents. They can be considered as promising raw materials in the northern regions of the Lena Basin (with deficiencies in motor fuels and lubricants) for conversion into liquid fuel, as supported by this study of their reactivity toward hydrogenation under hydrogen pressures to 10 MPa.

Composition and technological properties of coals from Mongolian deposits

The main characteristics of the composition of coals from Mongolian deposits and their reactivity in thermal dissolution and coking processes were determined. The thermochemical conversion of coals into hydrocarbon products was studied. It was found that Tavantolgoi coal is characterized by high coking properties with the yield of carbon residue to 82.3%. The composition of semicoking tar was studied by chemical analysis and IR spectroscopy.