Vol 52, No 4 (2018)

The key role of oxidation processes in the humification of peat-forming plant components was experimentally confirmed. A number of characteristic properties of the transformation of organic matter under conditions of the North, in particular, a decrease in the depth of humification and the pronounced predominance of the fulvate type of humification was revealed. It was established that special climatic effects are a factor affecting the formation of the group chemical composition of peat. It was demonstrated that, under the conditions of northern territories with consideration for the frost zone of a peat deposit, the conditions of oxidation and the kinetics of humification processes in the organic matter of peat in top and bottom layers can be essentially different; this fact explained the nonmonotonic changes in the characteristics of peat with the depth of occurrence. The effect of the bituminous component on the humification process of organic matter in the course of peat deposition was found; this was primarily due to the inhibition of the formation of polyconjugated structures, which are the main structure factor of humic substances.

The steam activation of anthracite (C^daf = 95.1%), which was preliminarily intercalated with nitric acid (140°C) and converted into anthracite nitrate (AN)—a material with intercalated nitrate anions that hypothetically formed intraskeleton ion pairs with the radical-cation polyarene fragments of coal, was studied. Activated carbons (ACs) were formed in the course of the gasification of AN with water vapor (850°C); their yield decreased with time in accordance with a first-order rate equation: the rate constant of AN gasification (0.015 min^–1) was higher by a factor of 3 than that in the case of the initial anthracite. The specific surface area (S_BET) of AC from AN was higher by a factor of 1.5 (940 vs. 600 m²/g), and it developed more rapidly by a factor of 4.5–10.0; that is, the intercalation promoted the formation of a porous structure. For AN, the dependence of SBET on the degree of combustion loss (φ) was extremal with a maximum at φ = 67%, and the values of S_BET = 800–1000 m²/g acceptable for carbon adsorbents were reached in a narrow range of φ = 60–70%. At φ > 70%, differences in the characteristics of ACs from AN and anthracite were leveled. In general, the influence of intercalation on the steam activation of anthracite was manifested in an increase in the rate of gasification (by a factor of 3), a larger specific surface area (by a factor of 1.5), and a considerable increase (by a factor of 4.5–10) in the rate of its formation.

Porous materials prepared from brown and black coals were used as sorbents for the extraction of chromium(VI) from aqueous solutions. They were compared with an AG-3 commercial sorbent. The effect of the acidity of reaction medium on the adsorption of chromium(VI) was established. The extraction of Cr(VI) from aqueous solutions reached a maximum in a range of pH 1.5–2.0. A kinetic study made it possible to determine equilibration times in the porous material–chromium(VI) solution systems.

The fractional distillation of crude shale oil was carried out for the removal of low-boiling components, and the yield of this fraction was 28 wt %. The catalytic removal of sulfur-containing compounds on a DN-200 commercial catalyst was performed. The degree of removal of sulfur compounds from crude shale oil was 94%. It was found that the shale oil after catalytic refinement satisfied the GOST [State Standard] requirements imposed on the concentration of sulfur compounds, and it can be used for the production of shale oil coke.

The experimental temperature dependence of the electrical resistivity of a model composition based on natural flake graphite was compared with the results of a mathematical simulation performed with the use of a flake graphite polycrystal model. For increasing the section of contacts between flakes, the density of the material was increased as a result of impregnation with pitch and the subsequent calcination. The average values of the sizes of flakes in the composition and the tabular values of the conductivity tensor of a graphite quasi-single crystal served as the parameters of calculations. Based on the results of the mathematical simulation, it was found that temperature cracking due to the shrinkage of flakes on cooling should be taken into account for the correspondence of computed values to the experimental results. This cracking almost ceased at temperatures lower than 200°C regardless of the compaction of the material.

An optimum composition and technological regimes of the production of composite wood–coal fuel briquettes from fine brown coal of the Kangalas deposit in the Republic of Sakha (Yakutia) and sawdust without the use of additional binding agents were established.