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.     

Deficiencies of State Standard GOST 1186-87

The Sapozhnikov-Bazilevich method, on which State Standard GOST 1186-87 is based [1], is preferable to other methods of investigating the clinkering properties of coal, in that it reproduces near-industrial coking conditions in miniature. This method permits study of the most important properties of coal and coal batches, formulation of their likely behavior in coking, and the prediction of coke quality.     

Influence of the coking properties of coal batch on coke properties

At OAO Zapadno-Sibirskii Metallurgicheskii Kombinat (ZSMK), research is undertaken to improve the optimization of coking batch. The basic approach, proposed by specialists from OAO Nizhne-tagil’skii Metallurgicheskii Kombinat, employs the coefficient K _opt, which characterizes the deviation of the batch from its optimal composition. The coking properties of the OAO ZSMK coal batch over the last few years are analyzed. After laboratory and industrial coking of batch with different K _opt, the strength and reactivity of the resulting coke is investigated. Evaluation of coke-grade coal in terms of its rank according to State Standard GOST 25543-88 proves inadequate, since coal of the same rank may differ markedly in coking properties. A method is established for assessing the optimality of the coal batch at OAO ZSMK.     

Reproducibility of plastic measurements: The need to modify State Standard GOST 1186-87

A very important characteristic of coking coal is its clinkering ability, i.e., its ability to form a nonvolatile solid residue, consisting of disparate grains, on heating in specific conditions. The clinkering ability of the coal is determined by the properties of its plastic mass. Various methods may be used to evaluate the plastic-ductile properties of the coal. However, since the 1930s, the main method used to evaluate the clinkering properties of coal, within the nations of the former Soviet Union, has been the Sapozhnikov-Bazilevich plastometric method, because it provides more information than competing approaches. For the same reason, the thickness of the plastic layer, which is one of the parameters determined by this method, is used for coal classification in State Standard GOST 25543-88 (Lignite, Coal, and Anthracite: Genetic and TEchnological Classification) and its Ukrainian counterpart DSTU 3472-96 (Lignite, Coal, and Anthracite: Classification). This explains the strict requirements on the accuracy and reliability of the plastometric characteristics.     

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     

Standards for determining the clinkering properties of coal

The replacement of State Standard GOST 9318-91 for the determination of coal’s clinkering properties (on the basis of the Roga method) by GOST R ISO 15585-2009 is assessed. It is shown that deficiencies of the ISO method limit the information that may be obtained. It is expedient to determine the clinkering properties of coal by the Roga method on the basis of the ISO 335:1974 standard.     

Identification of Russian coal on the basis of the swelling-index standard

The limitations of State Standard GOST 20330-91 for determining the swelling index are demonstrated in relation to coal with good clinkering properties. An expanded scale of standard profiles for coal identification is proposed.     

Kuznetsk Basin coking coal: Reserves and technological value

Reserves of Kuznetsk Basin coking coal are analyzed, in terms of rank composition and scope for coke production. The technological value of the coal is evaluated by the OOO VNITs Ugol method, in comparison with the rankings provided by State Standard GOST 25543-88.     

Evaluating coking resources. 2. State standard GOST 25543-88 as a coding system for coal and coal mixtures in evaluating their technological properties

The codification of coal in State Standard 25543-88 is compared with the international codification of coal of medium and high rank. The ranking of coking coal on the basis of State Standard GOST 25543-88 is evaluated.     

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.     

Evaluating coking resources 3. Optimal rank composition of batch

Several recommendations regarding the optimal rank composition of coal batch in bed coking are analyzed. It is shown that those approaches to evaluating the properties of the clinkering, coking, and lean components in optimal batch are inconsistent, do not result in optimal results, and do not yield coke of maximum strength.     

Industrial coking of coal batch without bituminous coal

For many years, Kuznetsk-coal batch has always included bituminous coal. Depending on the content of such coal, the batch may be characterized as lean, moderately clinkering, or bituminous. This classification was adopted by specialists of the Eastern Coal-Chemistry Institute (ECCI) in experimental coking at Magnitogorsk Metallurgical Works in 1945 [1]. Lean batch contained 10% Osinovsk bituminous coal (plastic-layer thickness y = 13 mm); moderately coking coal contained 25% bituminous coal (y = 16 mm); and bituminous batch contained 40% of such coal (y = 20 mm).     

Coke quality on adding coking byproducts to the batch

Conditions for the granulation and heat treatment of coking byproducts—heavy coal tar, acid tars, and distillation residues—are developed so as to produce suitable additives for coking batch. It proves possible to improve poorly clinkering batch by adding a mixture of coal and acidic tar from the sulfate department.     

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.     

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.     

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.     

Selection of nonclinkering and poorly clinkering coal for industrial use

The identification of nonclinkering and poorly clinkering coal suited to industrial use is of great importance. The classification of such coal by applicability is discussed. Criteria are needed for the selection of dual-purpose coals, with both fuel and nonfuel uses, within the framework of State Standard GOST 25543–2013.     

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.     

Equivalency of different methods of determining the clinkering properties of coal

The results for the clinkering properties obtained on the basis of State Standard GOST 9318-91 (ISO 335-74) and the ISO 15585 standard are compared.     

Clinkering Properties of Individual Fractions of Enriched Poorly Clinkering Coal

The clinkering properties of individual fractions of enriched poorly clinkering coal with limited metamorphic development are studied. Plastometric and dilatometric data are employed in studying the clinkering properties. It is found that, with change in the density of the individual fractions, their clinkering properties also change significantly. The results suggest that the difference in clinkering properties of individual fractions of enriched poorly clinkering coal is mainly due to the different quantity of liquid mass, which also differs in viscosity. On the basis of the results, optimal fractions of enriched poorly clinkering coal for use in coking batch may be formulated.