Vol 52, No 3 (2018)

A method for the desulfurization of brown coal by treatment in supercritical water (T = 673.15 K, P = 30 MPa) with the subsequent deposition of gaseous sulfur compounds on a copper substrate was proposed. The products were refined fuel with a low heat value of 24 MJ/kg and Cu₂S films with a thickness of 0.1 mm. The semiconductor Cu₂S films can be used for the preparation of thin-film photoelectric energy converters. The greatest degree of the removal of sulfur from the brown coal was observed after an hour. The main sulfur-containing gas formed upon the autoclave treatment of brown coal in supercritical water was H₂S.

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.

The results of studies on the oxidation of carbon black are represented. It was found that materials with different porosity can be obtained by varying the nature of an activating agent and the conditions of activation. A correlation of the sizes of carbon crystallites in the initial sample, the extent of their boundaries, and the rates of pyrocompaction and oxidation of these samples with the specific surface area of materials obtained upon activation was established.

The single-stage separation of fly ash from field 1 of the electrostatic precipitator of Reftinskaya GRES (Regional Thermal Power Plant), which burns coal from the Ekibastuz Basin, was performed by aerodynamic classification with the use of a flow of air. It was found that, at a constant airflow rate of 50 m³/h, the morphologically uniform fractions of small spherical particles with a narrow distribution, for which d_max was 2, 3, and 4 μm and d₉₀ was 4, 6, and 8 μm, can be separated by decreasing the speed of the classifier rotor from 22000 to 10000 rpm. At a minimum speed of 2000 rpm, the target product of separation was a narrow fraction containing large particles, which were characterized by d_max of 109 μm and d₉₀ of 205 μm. It was established that SiO₂ and Al₂O₃ were the basic chemical components of the fractions obtained, and the total concentration of these components was as high as 86–91 wt %. With increasing the size of fractions with dmax from 2 to 116 μm, a decrease in the concentration of SiO₂ and an increase in the amounts of Al₂O₃ and Fe₂O₃ were observed. The dependence of phase composition on the particle size was established for the small fractions: as d_max was increased in a range of 2–25 μm, a monotonic decrease in the concentration of a quartz phase and an increase in the concentration of mullite were observed; the concentration of a Fe-containing spinel phase also increased.

The results of the atomic-emission and X-ray spectrometry analysis of the mineral composition of humic fertilizers from brown coal are reported. Upon the treatment of soil with bedded out carrot and lettuce using humic fertilizers, a portion of the mineral matter of humates was transferred into the vegetable crops. It was found that the concentrations of boron, iron, magnesium, manganese, copper, molybdenum, calcium, potassium, cobalt, selenium, and zinc minerals in the vegetable crops increased by 13.7–281.0%.