Volume 61, Nº 2 (2018)

An approach is proposed for assessing the coking properties and value of coal during prospecting, extraction, and deep processing, so as to objectively identify clinkering coal suitable for the production of blast-furnace coke. As a trial, this approach is used in the assessment of clinkering and poorly clinkering coal of different maceral composition and metamorphic development in estimating the reserves in the Kuznetsk Basin.

Methods are proposed for the production of effective new reagents: binary salt systems that form low-temperature eutectics with water and readily melt ice, thereby preventing the freezing of coal in autumn and winter. Considerations of availability, cost, and physicochemical properties are of most importance in the selection of mixtures of organic and inorganic salts that are able to prevent the freezing of coal at temperatures down to–40°C. Research shows that the freezing point of solutions of organic-salt mixtures are lower than those of the individual mixture components. This may be explained by a synergetic effect. The consumption of the proposed salt mixtures for the prevention of coal freezing is considerably less than that of comparable systems containing only a single salt.

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.

Cyclic oxygen-bearing compounds and products of petroleum processing are considered as potential composite reagents. In searching for highly effective composite reagents differing in structure and elementary composition, one possible criterion is the energy of the hydrogen bond in intermolecular complexes between the reagent and the coal’s organic mass. The hydrogen-bond energy in intermolecular complexes between the reagent (cyclic siloxanes) and the coal’s organic mass is much higher than that in intermolecular complexes between water and the coal’s organic mass. That is responsible for the reagents’ high flotational activity. The use of distillation residues from the production of octamethylcyclotetrasiloxane improves the extraction of combustible mass in the concentrate in comparison with that currently attained at coal-enrichment facilities. In addition, the reagent consumption is decreased. Products of petroleum processing whose group chemical composition includes cyclic organosilicon compounds are recommended for industrial tests at Russian coal-enrichment facilities.