Influence of the quality of clinkering coal on coke strength

The dependence of the postreactive strength (CSR) and reactivity (CRI) of coke on the quality of the clinkering coals in the batch is considered. Optimal batch quality ensures maximum CSR.     

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.     

Effect of microwaves on poorly clinkering gas coal

The processes that occur in coal’s organic mass under the thermal action of microwave radiation are considered.     

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     

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.     

Influence of batch composition and clinkering properties on the hot strength of coke and blast-furnace operation

The relation of the basic characteristics of coking batch to the hot strength CSR and reactivity CRI of coke is established. The plastic layer of the batch components influences CRI and CSR. The relation of the batch composition to CSR and CRI is determined. When using enrichment batch that contains ～50.4% cokeforming coal, the best results are obtained: CSR = 61.8–62.3% and CRI = 26.4–26.7%.     

焦炭气孔率对焦炭热性能的影响

通过研究40kg试验焦炉单种煤焦炭、配合煤焦炭及工业焦炉焦炭的气孔结构及焦炭热性能,得出气孔率对焦炭热性能的影响。焦炭气孔率对焦炭热性能有较大影响,随着气孔率的增加,CRI增加,CSR降低;工业焦炉焦炭气孔率与焦炭热强度之间关系密切,气孔率每增加1％,CRI增加0．48％,CSR降低1．46％。用气孔率预测焦炭热性能,对指导焦炭生产、控制焦炭热性能具有指导意义。     

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.     

Additivity of clinkering measures when blending coal

The additivity of various measures of clinkering is verified for coal blends that contain imported coal.     

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.     

Influence of the moisture content of coal batch on coke quality

The strength of coke is greatly affected by the elevated and variable moisture content of the coal batch. The moisture content of the batch supplied to coal-preparation shops at coke plants must be no more than 6–7%. Otherwise, the plant must take measures to dry the coal.     

Influence of the size distribution of batch components on coke quality

Different degrees of crushing of coal in different technological groups, with constant rank and granulometric composition of the batch, significantly affect all the basic characteristics of coking: the packing density of the batch, the yield and strength (M ₂₅ and M ₁₀) of the coke, and its granulometric composition. That influence is practically always expressed through the products of factors (the contents of coals of different rank and different size class in the batch). This indicates systematic interaction of the components.     

Interaction of thermosetting plastics with clinkering coal

The influence of phenol-formaldehyde resin on the clinkering properties of coal batch is studied by means of the dilatometric method proposed by the Institute of Mining and Dnepropetrovsk Metallurgical Institute. For comparison, its influence on the clinkering ability is studied by the Roga method. The results show that this organic additive has a similar influence in both cases.     

Influence of microwave-treated G coal in the batch on the coke quality

The factors that affect the heating of poorly clinkering G coal in microwave treatment are identified. Mathematical models describing their influence on the thermoplastic characteristics of the treated coal and the resulting coke quality are developed. Recommendations are made regarding the composition of batch containing microwave-treated coal.     

气煤性质与粒度对焦炭显微结构的影响

对2种气煤不同粒级下参与配煤炼焦后的焦炭显微结构和焦炭热性能进行分析,结果表明:气煤的性质与粒度不同时成焦发生的界面反应激烈程度不同,其结果影响焦炭热性能.气煤的粒度越小,界面接触面积越大,界面反应越激烈.气煤中活性组分含量越高,界面反应越激烈.     

炼焦煤中灰分对焦炭热性能的影响

研究了炼焦煤的灰分和催化指数,通过小焦炉实验进行了焦炭的反应性和反应后强度的测定。结果表明,灰分催化指数对焦炭的反应性和反应后强度的影响显著。焦炭的反应性与灰分碱性催化指数呈正线性相关,焦炭的反应后强度与灰分碱性催化指数呈负线性相关。     

Influence of coal preparation and coking conditions on coke reactivity

The influence of various technological factors on the high-temperature properties of coke is investigated. It is found that factors facilitating an orderly organic structure of the coke (fine grinding and compaction of the batch, increased conditioning of the coke, dry slaking, the introduction of lubricant additives in the batch) reduce the reactivity of the coke; by contrast, introducing coke fines, intermediate product, and red mud in the batch increases the reactivity.     

入炉煤水分对炼焦过程及焦炭质量的影响

通过测定入炉煤水分分别为1%、6%和12%时煤料堆密度、升温速度及坩埚焦性质,得出入炉煤水分对其性质的影响。降低入炉煤水分虽然对煤料本身性质影响不大,但是其在炭化室内结焦过程的动态发生了显著变化,可显著提高焦炉生产能力及改善焦炭质量。入炉煤水分为1%时,煤料堆密度、升温速度及坩埚焦的性质都大大好于入炉煤水分为6%和12%这两种情况。     

The effect of plastic size on coke quality and coking pressure in the co-carbonization of coal/plastic in coke oven

In the recycling process of waste plastics using coke ovens, coals and added plastics are carbonized and changed into coke, tar, oil and coke oven gas in a coke oven chamber. In this study, the effect of added plastic size on coke quality and the effect of plastic addition on coking pressure was investigated. In the case of a plastic addition rate of 2%, the coke strength reached a minimum at the particle size of 10 mm for polyethylene (PE) and 3 mm for polystyrene (PS). The mechanism was attributed to the weak coke structure formed on the interface between plastic and coal. The result indicates that large or small plastic particles are favorable in order to add waste plastics to blended coals for coke making without affecting coke strength . Furthermore, it was also shown that a 1% addition of large size agglomerated waste plastics to blended coals did not increase coking pressure. Based on this fundamental study, and considering the ease of handling plastics, we have determined that the size of waste plastic used in a commercial-scale recycling process of waste plastics using coke ovens is about 25 mm. Nippon Steel Corporation started to operate a waste plastic recycling process using coke ovens at Nagoya and Kimitsu works in 2000 and at Yawata and Muroran works in 2002. Now the total capacity is 120,000 tons per year as of 2003 and this process is operating smoothly.