Coking theory: Internal stress in the coal batch

The development of local internal stress in the coal batch is analyzed on the basis of recent theoretical and experimental data. Its influence on coke quality is demonstrated. The influence of mineralized rock particles and large hard-to-crush particles of highly metamorphic coal (including petrographically uniform coal) is considered. The results of appropriate preparation of coal batch for coking are described.     

汾西矿业焦煤、肥煤的焦化特性指标分析

对汾西矿业不同煤化程度焦煤、肥煤的煤质指标、基氏流动度、奥亚膨胀度和镜质体最大反射率进行分析。结果表明,不同变质程度的焦、肥煤具有明显不同的煤质特征,低变质程度肥煤具有高挥发分、高流动度和高膨胀的特点;高变质程度肥煤具有低挥发分、低流动度和低膨胀的特点。同时,通过焦、肥煤的焦炭强度分析,为各焦化和钢厂的配煤炼焦提供依据。     

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.     

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.     

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.     

煤沥青与石油沥青共混改性及其热解特性

考察了不同添加量的煤沥青四氢呋喃萃取物(THFS)对石油沥青的改性,随着THFS添加量的增多,改性沥青针入度降低,软化点升高,延度下降,参照英国标准(BSI BS—3690)得出最佳添加量为8%。利用TG-FTIR、FTIR对改性沥青进行了表征,结果表明:THFS、改性沥青的失重率大于基质沥青70的失重率; THFS在700～900cm^-1处芳香烃类的透射峰强度明显强于基质沥青与改性沥青;沥青老化后在2953cm^-1和1377cm^-1(—CH₃)、1461cm^-1和2924cm^-1(—CH₂—)处透射峰逐渐增强;1600cm^-1(C=O和苯环C=C)透射峰逐渐增强;沥青热解半焦中的脂肪烃类物质含量较少,主要以高度缩合的稠环芳香烃类物质为主;沥青在老化过程中主要发生了氧化、裂解、加成、聚合、缩合等反应。     

煤沥青的改性研究进展

介绍了传统的煤沥青改性方法,综合概述了国内外对煤沥青的流变性、结焦性、中间相的形成以及煤沥青对石油焦的润湿性和渗透性等方面的研究进展,进一步介绍了环保沥青方面的研究现状。在此基础上对煤沥青的改性研究前景进行了展望。     

Thermooxidation of coal tar pitch with the return of pitch distillates

The thermooxidation of moderate-temperature coal tar pitch with the return of pitch distillates is investigated, in conditions such that high-temperature grade-C pitch is obtained. Gas-liquid chromatography shows that the content of polycyclic aromatic hydrocarbons included in the list published by the United States Environmental Protection Agency (EPA) is not significantly different in the pitch samples before and after oxidation.     

Carbonization of coal pitch with additives

The ability of organic and inorganic additives (polyethylene terephthalate, titanium dioxide, finely disperse carbon, petroleum bitumen) to reduce the carcinogenic impact of coal-pitch carbonization is studied. Additives may reduce the quantity of pitch sublimates and their content of carcinogenic polycyclic aromatic hydrocarbons. Some additives are able to reduce the benz[a]pyrene content in the exhaust gases, but its complete elimination is impossible, since benz[a]pyrene is a natural product of the high-temperature pyrolysis of organic materials. For this reason, additions of petroleum products to coal pitch cannot reduce the benz[a]pyrene emissions in the exhaust gases.     

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).     

Coking of batch with modifying additives at ChAO zaporozhkoks

Efforts to improve the quality of blast-furnace coke produced from modified batch at ChAO Zaporozhkoks are described. The batch is modified by introducing fine-grain electrocorundum and carborundum (silicon carbide). The introduction of a fixed quantity (0.25 wt %) of nonclinkering additives permits adjustment of the processes in the plastic state so as to improve the coke strength. The effect of such modification on coke quality depends significantly of the rank composition of the batch. The use of additives is especially important for batch with poor clinkering properties.     

Effect of erucic acid on the rheological and surface properties of coal tar pitch

Coal tar pitch (CTP) was modified using erucic acid, CH₃(CH₂)₇CH=CH(CH₂)₁₁COOH, and the rheological and surface properties of the modified CTP were evaluated. The effect of erucic acid was investigated using a rotational viscometer as well as by drop and weight tests. The modified CTPs were characterized by Fourier transform infrared spectroscopy and scanning electron microscopy following a carbonization process. The results showed significant differences in several properties between the CTP and modified CTPs, such as decreases in viscosity, wetting temperature, and softening point when erucic acid content was 1–3 wt% of CTP. An improvement in bonding between the coke and the modified CTP can be achieved when the coke value remained 62%. Moreover, a modification mechanism was proposed to explain the physical plastification of CTP modified with erucic acid.     

贫煤与煤沥青共炭化研究

进行了不同配比的煤沥青和贫煤的共炭化研究,研究表明,煤沥青与贫煤共炭化时的相互作用是物理融合和化学相互作用的共同作用。其中物理融合表现在使焦炭界面结合状态改善,化学相互作用表现在煤沥青使贫煤的炭化性能发生变化。随煤沥青配比的增加,配煤黏结性有较大改善,焦炭OTI值增大,ISO值减小。煤沥青通过增大焦炭光学组织各向异性程度,使焦炭的反应性降低,反应后强度提高。     

煤焦油沥青添加废聚丙烯塑料制备改性中间相沥青

煤焦油沥青的甲苯可溶物中添加废聚丙烯塑料,对生成中间相的可溶性、共熔性、流动性、分子结构的变化进行了研究。结果表明,可溶性中间相沥青的含量从22%提高到52%,并且中间相沥青的光学结构从中间相含量为74%、内含各向同性相的粗镶嵌结构改善为中间相含量为100%的广域融并体。中间相的表观黏度分析显示添加废聚苯丙烯塑料在整个热处理过程中由于共熔效应的增强,降低了沥青基质的表观黏度,并且中间相沥青从触变性变为非触变性。红外和核磁共振分析表明通过添加废聚苯丙烯塑料,中间相沥青吡啶可溶物发生烷基增多的现象,出现较多的α取代亚甲基结构。而X射线衍射结果显示在添加废聚苯丙烯后由于烷基的增多,使芳香平面分子堆积变好。