Carbonization of coals into anisotropic cokes: 6. Formed cokes of high density and optical anisotropy from non-fusible and slightly fusible coals

A procedure for the preparation of solid formed coke of enough adhesion and anisotropic development for use in the blast furnace has been studied, using non-fusible and slightly fusible coals with petroleum cocarbonizing additives. The coke precursor was prepared through the copreheat-treatment of coal and a suitable additive in adequate quantity under stipulated conditions. The desired coke was produced by carbonization after forming with a press. The conditions for the copreheat-treatment have been carefully examined in terms of the temperature, time and heating devices. The behaviour of coals during copreheat-treatment and carbonization were discussed in terms of coal ranks, comparing this behaviour to the liquefaction reactivity and thermal stability of their liquefied product.     

Carbonization and liquid crystal (mesophase) development. 14. Co-carbonization of coals with A240 Ashland petroleum pitch: effects of conditions of carbonization upon optical textures of resultant cokes

This study examines the effect of pitch concentration, rate of heating, soak temperature and time of soak upon the optical texture of cokes prepared from the co-carbonizations of a coal (Oxcroft-Clowne, NCB Rank 802) and three vitrains of NCB Rank 204, 801, 902 with Ashland A240 petroleum pitch. Using the coal (Rank 802) with 10 wt % and 25 wt % additions of pitch caused progressive penetration of the pitch into the coal with a resultant development of a mozaic anisotropy in the coke to replace partially the original coke isotropy. With 50 wt % addition of pitch almost all of the coal particles, 600 to 1100 μm in size, were modified during carbonization. Some pitch coke was formed. For the coal and three vitrains with increasing rates of co-carbonization from 0.5–10 K min^?1 to 1200 K, using 25 wt % of A240 pitch, resultant cokes showed progressively increased extents of modification. For the two vitrains (Rank 801, 902) soaking at temperatures of 650–690 K caused a decrease in the extent of modification of isotropic coke when compared with the coke of HTT 1200 K. Evidently fast heating rates create the conditions of fluidity necessary for the pitch to modify the coal leading to growth of mesophase and anisotropic coke.     

Mechanism of carbonization of a semianthracite

The carbonization of a semi-anthracite which produced a domain texture of large isochromatic units was studied to elucidate the mechanism for this type of anisotropic development. The observation of a series of its carbonization residues at several temperatures indicated that the anisotropic domains appeared simultaneously and no stepwise growth was observable. However, its co-carbonization with decacyclene or A240 pitch followed the typical mesophase mechanism to give a flow or coarse-mozaic texture which was quite similar to that observed in the coke produced from its quinoline extract. In contrast, the residue after quinoline extraction retained on carbonization the same basic anisotropy as the coal. The structure of the original coal and the coke was studied by topological observation before and after quinoline and gasification etching. The results suggest that during carbonization the preordered structure of the semi-anthracite is slightly rearranged, with the aid of the quinoline-soluble matter, to become more highly ordered giving a domain texture which corresponds to the isochromatic anisotropic regions of its basic anisotropy.     

Carbonization and liquid-crystal (mesophase) development. 18. carbonization of coal-extract solutions (non-hydrogenated): influence of digestion conditions upon optical texture of cokes

Coal-extract solutions have been produced by the dissolution of a prime coking coal in anthracene oil followed by the removal of the undissolved solids. A range of coal-extract solutions prepared under different conditions was carbonized and the optical texture of the polished surfaces of the resultant cokes were assessed. The coal-extract solution prepared with the longest digestion time and at the highest temperature produced a coke with the largest anisotropic domains with some flow structure. Removal of the anthracene oil component of the coal-extract solution by extraction with selected solvents modified the carbonization behaviour such that although the coke yield increased substantially there was a significant decrease in the size of the anisotropic domains of the resultant cokes.     

Liquefaction of subbituminous coals under apparently non-hydrogenative conditions

Reactivities of several coals of different ranks have been examined in degrading extractions with aromatic solvents under apparently non-hydrogenative reaction conditions. Pyrene and A240 pitch liquefied the fusible coals in high yields and the slightly-fusible coals in moderate yields, indicating the importance of fusibility in such liquefaction processes. A240-LS pitch is a powerful solvent for slightly-fusible coals. Considerable amounts of pyridine- or THF-soluble fractions were produced especially with A240-LS pitch. A240 pitch is a better solvent than pyrene for some slightly-fusible coals. However, the extent of depolymerization of liquefied coal, pyridine- or THF-solubility, was definitely inferior. Yields of such fractions are higher for lower-rank coals. The mechanism of coal liquefaction under apparently non-hydrogenative conditions is discussed with emphasis on the stabilization of thermal fragments derived from the coal.     

Measurement of anisotropic development in a low-rank coal using e.s.r. spectroscopy and optical texture

Anisotropic development in a low-rank coal (Cerrejón coal) has been induced using natural heavy oil or anthracene oil as additives in a cocarbonization system at 500 °C. The heavy oil showed better modifying activity. To monitor the anisotropic development optical microscopy and e.s.r. spectroscopy have been used. The concentration of stabilized free radicals, measured at room temperature (trapped free radicals) increased with anisotropic development. The concentration of stabilized free radicals allows interaction in the carbonization system to be followed even when the microcrystallinity of the anisotropic phase is too small to be observed under the microscope.     

Coal carbonization and coke anisotropy: some comments

Previously published work is presented in modified form to emphasise that, except under special circumstances, spherical mesophase units have not been observed during coal carbonization and that the viscosity of the fluid phase, considered so important during pitch carbonization, has no strong bearing on the size of anisotropic units found in metallurgical coke.     

Carbonization and liquid-crystal (mesophase) development. 13. Kinetic considerations of the co-carbonizations of coals with organic additives

Five coals, of rank from an anthracite to a non-caking coal, have been carbonized singly and also cocarbonized with decacyclene, mixing ratio 7:3, in the temperature range 648 K to 823 K, heating at 10 K min^?1, with various soak times. The objective of the study is to derive the basic factors which influence the kinetics of formation of mesophase and anisotropic coke. Accordingly, resultant cokes were polished and surfaces examined by reflected polarized light in an optical microscope. The size, shape and extent of anisotropic development is discussed in terms of the conditions of carbonization and the rank of coal. In these systems a somewhat larger optical texture results in cokes produced at the higher carbonization temperatures. The temperature of onset of growth of anisotropic carbon in co-carbonizations was below that of either the coal or the decacyclene. Reactivities are evidently modified. The origins, growth and coalescence of growth units of anisotropic carbon in these cocarbonizations of coals with decacyclene are demonstrated.     

E.s.r. study of formation of coke texture

The optical coke texture is a major factor in the high-temperature properties of metallurgical coke but the mechanism of formation of coke texture is not established yet. By studying the carbonization process during the formation of optically anisotropic coke with an e.s.r. spectrometer fitted with a high temperature cavity a relation between the concentration of the free-spins during carbonization and coke texture has been inferred for some organic compounds used as the model materials and for coals covering a range of coal rank.     

Three-dimensional modelling of in-furnace coal/coke combustion in a blast furnace

A three-dimensional mathematical model of the combustion of pulverized coal and coke is developed. The model is applied to the region of lance-blowpipe-tuyere-raceway-coke bed to simulate in-furnace phenomena of pulverized coal injection in an ironmaking blast furnace. The model integrates not only pulverized coal combustion model in the blowpipe-tuyere-raceway-coke bed but also coke combustion model in the coke bed. The model is validated against the measurements under different conditions. The comprehensive in-furnace phenomena are investigated in the raceway and coke bed, in terms of flow, temperature, gas composition, and coal burning characteristics. The underlying mechanisms for the in-furnace phenomena are also analysed. The simulation results indicate that it is important to include recirculation region in the raceway and the coke bed reactions for better understanding in-furnace phenomena. The model provides a cost-effective tool for understanding and optimizing the in-furnace flow-thermo-chemical characteristics of the PCI operation in full-scale blast furnaces.     

煤种及活化条件对活性焦脱硫性能的影响

在流化床上制备活性焦(AC)并考察了煤种及活化条件(活化温度、活化时间及活化介质中水蒸汽浓度)对其脱硫性能的影响. 结果表明彬县煤是制备脱硫用活性焦的较佳煤种，在活化温度为800~900℃、活化时间为20~60 min、水蒸汽浓度为30%~80%(j)的范围内，制得的活性焦碘值为573~805 mg/g、苯甲酸吸附量为0.24~0.26 mmol/g、硫容(SO2)为174~275 mg/g.     

Carbonization of coals to produce anisotropic cokes. 1. Modifying activities of some additives in the co-carbonization of low-rank coals

Using low-rank coals, the modifying activities of some petroleum, coal tar and aromatic hydrocarbon additives have been examined to find procedures for their utilization in the preparation of blast furnace coke. Petroleum pitch, especially after hydrogenation, exhibited excellent modifying activity even with non-fusible coals. In contrast, the activity of coal tar was very limited with such coals. The napththenic component, revealed by n.m.r. of the additives, appears to be important in the co-carbonization by inducing fusibility and anisotropic development in such coals. Co-carbonization to recover the dehydrogenated additives was attempted. However, there was no development of the anisotropy in the resultant coke by dissolution of the coal particles although the coal particles were firmly fixed in the matrix. Acid-refluxing treatment of non-fusible coals was found to enhance their modification susceptibility, indicating that some of the acid-soluble mineral matter is important in the thermal depolymerization or fusion process of the coal.     

煤制CO和焦炭制CO在醋酸生产中的成本分析

羰基合成醋酸是醋酸生产的主要方法,而羰基合成过程中CO的成本直接影响着醋酸生产成本。对以煤和焦炭为原料生产CO的工艺、能耗、物耗进行了分析,分别建立了原料与成本之间的数学模型,计算出不同煤价和焦炭价格下的CO成本。通过对比CO成本,得出了在目前价格形势下,以煤为原料生产CO成本低于以焦炭为原料生产CO。     

我国煤系针状焦的研究及生产状况

概述了中国煤系针状焦的研究发展过程,讨论了国内煤系针状焦的基础理论研究及工业试验、生产状况,着重介绍了原料预处理、延迟焦化制备生焦和回转窑煅烧的煤系针状焦生产工艺过程,评价了目前国内煤系针状焦的质量和应用状况。     

炼焦煤镜质组反射率分布对焦炭显微结构和热性能的影响

对近年来武钢炼焦单种煤和配合煤进行镜质组反射率分布分析,并对相应焦炭进行显微结构和热性能测试。实验发现,炼焦煤镜质组反射率分布的变化,引起焦炭显微结构的变化,而焦炭显微结构的变化最终影响焦炭的热性能;要使含碱大型高炉用焦炭的热性能保持良好,焦炭显微结构中的各显微组分要有合理的比例,细粒结构不能过高,其他各向异性结构也不能过高。     

酒钢焦炭抗碱性及降低灰硫研究

分析了酒钢焦炭质量总体情况,认为焦炭灰硫含量在全国偏高;再者鉴于目前全国炼焦煤供应紧张,炼焦煤需求成为酒钢生产发展的瓶颈。因此,寻找低灰、低硫、廉价的新煤源成为酒钢当务之急。对低变质程度A煤研究了其在配煤中的作用和成焦后的性能,特别是高温抗碱性及其对焦炭降灰降硫的影响;对B煤也作了相应探索性的试验,均得出对生产有益的预期结果。     

Carbonization and liquid-crystal (mesophase) development. Part 4. Carbonization of coal-tar pitches and coals of increasing rank

Coal-tar pitches, from coals of different rank and with various quinoline-insoluble contents, were carbonized under pressure (67 to 200 MN m⁻²) to maximum temperatures of 923 K. The resultant cokes were examined by optical and scanning electron microscopy in terms of size and shape of anisotropic structures within the coke. Natural quinoline-insolubles and carbon blacks both destroyed growth of the mesophase and development of anisotropy. Graphite particles (<10 μm) promoted growth and coalescence of the mesophase. Fourteen coals, of carbon content 77 to 91 wt%, VM 41 to 26%, were similarly carbonized under pressure. In the lower-rank coals no microscopically resolvable anisotropic mesophase was produced, but at a carbon content of 85% anisotropic units 1–2 μm in diameter were detected, increasing in size at a carbon content of 90% to 5 μm diameter. Results are discussed in terms of the origins of anisotropic mosaics observed in cokes, their variation in size with coal rank, and their significance in the carbonization of coal.     

An evaluation of methods for enhancing the CO2-reactivity of a caking bituminous coal

An evaluation of a variety of reactivity enhancement procedures has been carried out for one bituminous coal (Pittsburgh No. 8). The relative merits of each type of method have been assessed and the extent to which coal char reactivity could realistically be enhanced for gasification by carbon dioxide has been established. Investigations have revealed two main classes of pretreatment type. The first group, consisting of non-catalytic pretreatments such as preoxidation, solvent extraction and co-carbonization with inert materials produced only a moderate increase in char reactivity relative to the untreated parent coke. In contrast, however, the second group, consisting of catalyst pretreated chars, resulted in a large increase in char reactivity compared with that of the parent coke. Group one pretreatments also generally produced non-caking chars with increased microporosity and isotropic carbon texture compared with the largely macroporous anisotropic parent coke. The microporosity was believed to be responsible for the significant pore diffusion/development effects found with these chars during the course of gasification. The most reactive chars were produced by (i) co-carbonization with 15wt% K₂CO₃, and (ii) preoxidation plus 2wt% potassium by ion-exchange. The latter char is preferred on the basis of its more efficient use of catalyst and completely non-caking characteristics.     

我厂炼焦用煤的水分控制与管理

本文叙述了绍兴钢铁总厂煤干燥装置的工艺及设备概要。在对煤干燥装置运行采取了强化管理后，使炼焦用煤水分降低且控制在要求范围内，为煤的配合、粉碎以及焦炉生产的顺利进行创造了良好的前提。同时，焦炉生产显示出较好效益。     

浅谈提高炼焦煤质量的管理方法

焦化厂在备煤和炼焦工艺条件稳定的情况下,装炉煤料的质量是保证焦炭质量的重要因素。只有不断提高进厂炼焦煤的质量,焦炉才能更好的炼出高质量的焦炭。文章根据生产经验提出了几点提高炼焦煤质量的管理方法。