Polyene model of coal structure and metamorphism

Eight coal ranks (G, GZhO, GZh, K, KO, KS, and T) are investigated by IR spectroscopy in the range between 1800 and 650 cm–1, with polynomial decomposition of the spectra obtained. The similarities and differences in the IR spectra for two series of coal are noted: specifically, fat coal (Zh, GZh, GZhO, and G) and coking coal (K, KO, KS, and T). For both series, we consider the regions of the spectra containing narrow absorption bands. On passing from Zh and G coal in the fat set and from K to T coal in the coking set, the intensity of the IR absorption bands at 1450 and 1370 cm^–1 declines, on account of deformation C?H vibrations of the CH₂ and CH₃ groups, while the absorption of oxygen-bearing groups appears. These experimental data are inconsistent with accepted concepts regarding the metamorphism on passing from gas coal (rank G) to lean coal (rank T).     

Technological value of coal used for coking

The technological value of coal used for coking is analyzed, with particular attention to clinkering coal, the coke group, and lean additives, as well as G and GZhO coal. A relation is established between the technological value of the coal components and their permissible content in coking batch so as to produce coke of constant strength (M ₂₅ = 87%). The precision in determining the technological value of coal is assessed.     

Batch preparation at OAO Dneprokoks: Stabilization of coke quality

Industrial coking data indicate that, given the scarcity of Zh and K coal, GZh coal from Raspadskaya enrichment facility may be used as the clinkering component in coking batch. To obtain blast-furnace coke of satisfactory quality, the content of Zh or K coal in the batch may be no less than 10% in the presence of a large quantity of petrographically heterogeneous lean additives.     

Terminology and batch formulation in coke production

The technological value of coking coal may usefully be discussed in terms of the coking potential. Attention focuses on the coking potential of clinkering coal—alone, in blends from enrichment plants, or in coking batch. Calculation of the batch composition on the basis of predictors of technological value is proposed.     

Clinkering properties of rammed coking coal and coal batches

The clinkering properties of rammed coking coal and coal batches are investigated. There is a close relation between the clinkering properties and coke quality.     

Modification of poorly clinkering coal for use in coking

If coal is modified by the volatile products formed in pyrolysis, high-quality blast-furnace coke may be produced from batch with a smaller proportion of expensive clinkering coal. In such coking, the batch is modified in the coking chamber; its clinkering properties are improved as a result of partial hydrogenation. New parameters are proposed to describe the modification of the batch; the variation in clinkering properties is established as a function of these parameters. The quality of the coke obtained from modified coal batch is assessed. The relationship between coke quality and the batch composition is determined. The formulas obtained may be used to predict coke quality. Tests show that partial hydrogenation improves coke quality     

Modified coal batch in coking

The influence of volatile products from low-metamorphic poorly clinkering G coal on plasticmass formation in rammed batch during coking is considered. An experimental batch of modified coke has been produced at PAO Alchevskkoks.     

Assessing the value of coking coal in terms of coking properties and genetic compatibility

On the basis of new research by the Sapozhnikov method (State Standard GOST 1186), as well as data on the yield of volatiles (State Standard GOST 6382) and the petrological characteristics, new definitions are proposed in assessing the clinkering and coking of coal for bed coking. Under that proposal, clinkering properties and coking properties would refer exclusively to samples of individual coals; clinkering ability and coking ability would apply to coal blends and coal batch. As is shown, data for the petrographic composition and vitrinite reflection coefficient permit assessment of the genetic compatibility of coal, which may be used as a behavioral characteristic of coal in batch for blast-furnace coke production.     

Properties of Ulug Khem coal. 3. Quality of coke from batch containing Elegest coal

In the laboratory coking of production batches at OAO EVRAZ ZSMK, including those containing coal from the Elegest deposit, special attention is paid to batches with different quality of the clinkering, coking, and lean components, so as to determine the maximum possible content of Elegest coal in the batch if the coke produced is to be satisfactory quality for use in blast furnaces at OAO EVRAZ ZSMK with pulverized-coal injection.     

Improving the preparation of coal batch for coking

Various methods of preparing coal for coking are analyzed. Laboratory experiments are conducted with a view to obtaining higher-quality coke from batch with a high content of poorly clinkering coal.     

Direct determination of the clinkering properties of rammed coal and batch

A direct method is proposed for determining the clinkering properties of rammed coal and batch used for industrial coking. This method permits evaluation and selection of individual clinkering coals and satisfactory prediction of the coke quality obtained with preliminary ramming of the coal batch.     

Calculating the relative value of coal in Russian coking-coal markets

In order to improve the pricing of Russian coking coal, a method is proposed for calculating the relative technological value of purchased coking-coal batches. The basic idea is to compare the parameters of optimal coking batch and coking batch that includes the purchased coking-coal concentrate and other coals available to a particular buyer. It is shown that the relative technological value of a particular batch of coking-coal concentrate will depend on the parameters of the other coals included in the coking batch at a particular coke plant.     

Rank assignment of coal in terms of its clinkering and coking properties

Comparison of the clinkering and coking properties of coal from different basins indicates that the rank boundaries adopted in State Standard GOST 25543–2013 in terms of the plastic-layer thickness do not correspond to the boundaries in terms of the coking properties. The coal samples are arranged in order in terms of the coking capacity K^cc and the coke-forming capacity K^cfc, and a classification of coal ranks on the basis of the coking properties is proposed.     

Optimal preparation of oxidized coal

The oxidation index is an important characteristic of coal and coal batch, indicating the change in coking properties on oxidation. The coke obtained from coal batch containing poorly clinkering oxidized coal has a higher content of isotropic carbon and a lower content of anisotropic carbon. That explains its increased reactivity and impaired mechanical and postreactive strength. The oxidation on storage is greatest for small coal classes (<0.5 mm). Preliminary removal of <0.5 mm oxidized coal markedly improves the reactivity and also the mechanical and postreactive strength. A method of preparing oxidized coal for coking is proposed: finer grinding (until the content of the ≤1 mm class is 100%). That considerably reduces the influence of the oxidized coal on the quality of the coke produced.     

Reducing the sulfur content of coke by increasing the content of thermally conditioned g coal in the batch

In periods of economic growth, Ukrainian coke plants face a shortage of Zh and K coal, because of the high demand. In periods of economic stagnation, conversely, there is an excess of Zh coal, on account of the drop in demand. However, it is still important to introduce poorly clinkering coal in the batch. Ukrainian coal is known to have high sulfur content (up to 3.5% S). About 45–75% of that sulfur is passed on to the coke. Consequently, in order to reduce the sulfur content of the coke, it is expedient to include poorly clinkering coal in the batch, since typical low-carbon Donets Basin coal has a low desulfurization coefficient: 0.63. The corresponding figure for moderate-carbon coal is 0.70. Hence, by increasing the content of poorly clinkering coal in the batch, the sulfur content and cost of the coke may be reduced.     

Modification of poorly clinkering DG coal

In a recent issue of this journal, Malyi described experiments on the modification of DG coal for its subsequent use in coking batch in place of G coal. Analysis of that paper shows that, contrary to Malyi’s statements, there is no shortage of G coal, because the Donets Basin comfortably meets the demand. The model mixture that Malyi uses for modification is complex in composition and contains considerable sulfur. He does not state its properties or the available reserves. Malyi’s ideas regarding the pyrolysis of coal are shown to be very contradictory, while his experimental data prompt skepticism, since the measured ash content, total sulfur content, and clinkering properties of the batch differ from those calculated on the basis of the properties and proportions of the batch components. When using batch that contains modified DG coal in place of G coal, the coke yield is reduced, and its quality is impaired. These findings support the conclusion that Malyi’s research is unnecessary, unpromising, and unworthy of further consideration.     

Determining the coking properties and technological value of coal and coal mixtures

A method is developed for determining the coking properties and technological value of coal from newly identified beds or new sections of existing mines. The coking properties are assessed on the basis of predictions of the strength and reactivity of coke obtained from batch containing coal from single beds and coal blends. The prediction of coke quality is based on the chemical and petrographic characteristics of the coal.     

Coking properties of coal pitch in coal batch

The coking properties of coal pitch depend significantly on its fractional composition, which determines the set of structural components involved in meso-phase formation. The optimal combination of high-molecular aromatic compounds, polycyclic compounds of intermediate molecular mass, and hydrogen-donor hydroaromatic components corresponds to a ratio of pitch fractions α: β: γ = 1: 2: 2. This is typical of coal pitch with a softening temperature of 75–85°C. Such pitch is the best clinkering additive to coking batch, resulting in the production of coke of maximum strength.     

Oxidized coal in coking: A review

A literature review shows that the oxidation of coal changes its granulometric composition, packing density, moisture content, and clinkering properties, the quality of the resulting coke, and the yield of coking byproducts. On account of the increased proportion of oxidized coal in coking batch, research is expedient in order to formulate recommendations regarding its use.     

Assessing the Coking Properties and Value of Coal for Blast-Furnace Coke Production

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.