Properties and structure of group components separated from vitrites of coking coals by selective thermosolvolysis

The process of progressive and continuous thermosolvolysis of coking coal vitrites was carried out. The properties and structure of the extracts and the extraction residue as well as the influence of the degree of extraction on the properties of the resultant group components were examined. An increase in aromatic character of the extracts with increasing degree of extraction is observed, and the same increase of aromatic character can be seen for the extracts obtained in the same extraction time with an increase of the degree of coalification of the parent vitrites. The changes in the coal structure after extraction of thermobitumens depend on the degree of coalification of the parent vitrites, they are largest for the gascoal vitrite.     

Structure of cokes from coking coal vitrites

The coking process of vitrites and thermobitumens separated from vitrites was examined; structural X-ray and microscopic examinations of the cokes obtained were carried out. A correlation between reflectance distribution of vitrites and microscopic structure of their cokes was found.An increase in the structural ordering of the cokes from vitrites, passing from cokes of gas coal to cokes of orthocoking coals, is observed. It is accompanied by an increase of the optical anisotropy of the resultant cokes; this anisotropy first appears in coke from gas-coaking coal.The cokes from the thermobitumens are lower ordered than the cokes from parent vitrites but all these cokes are partially or entirely optically anisotropic.Total removal of the thermobitumens from coals deprives the cokes from the residues after the extraction of any optical anisotropy.     

Effect of low-volatile additives on the structure and strength of cokes

Blends of medium-volatile or high-volatile coals have been carbonized in a 7 kg oven with low-volatile coals (6–16% VM, dmmf). A comparison is made of the strength and structural properties of these cokes with those of the cokes made under corresponding conditions from the medium or high-volatile coals alone. With increasing levels of addition of the low-volatile coals the tensile strength of the blend cokes generally attains a maximum and then decreases. These strength changes are related to changes in porosity, pore-wall thickness and pore dimensions. Coals which display some degree of plasticity and which are weakly caking improve coke quality by altering the pore-structure due to the combined effects of decreasing the pore diameter and slightly increasing the wall thickness. Those additives which are non-caking act primarily as wall thickeners.     

Mineral matter effects on air-oxidation of cokes from a coking coal

Indigenous mineral matter in coal affects the chemical reactivity of resulting cokes through both catalytic graphitization and catalytic gasification. The significance of both catalytic effects on air-oxidation was examined using cokes from a medium-volatile bituminous coking coal with 9 wt% mineral matter. Catalytic graphitization by mineral matter enhanced the reactivity of the resulting coke in spite of the formation of highly crystalline carbons. This effect, however, was less than that of catalytic gasification by mineral matter. The coke from the acid-treated predemineralized coal exhibited no catalytic effects but was the most reactive. The implications of these results are discussed in detail.     

中高硫瘦煤配煤炼焦试验及应用研究

为扩大炼焦煤资源,降低配煤成本,采用鄂尔多斯盆地南部渭北煤田西部矿区10号煤层的中高硫瘦煤为试验煤样,分析了煤样基本性质,说明其具有高硫、低灰的特点,黏结指数和胶质层厚度较一般瘦煤高,活惰比接近2,黏结性和结焦性较好。通过中高硫瘦煤单独成焦试验、煤岩学模拟配煤、工业焦炉炼焦试验,验证中高硫瘦煤配煤炼焦的可行性,确定中高硫瘦煤配煤炼焦优化方案。结果表明:中高硫瘦煤配煤炼焦可行,应尽量控制中高硫瘦煤配入量在10%以下,多配入强黏结性煤,以提高焦炭的热态强度。中高硫瘦煤配煤炼焦工业应用表明:配入中高硫瘦煤3%~7%可生产出质量合格的焦炭,扩大了炼焦用煤范围,降低了配煤成本。     

Properties of Taiwan coking coal

Three Taiwan coking coals, Shuangchi HV, Fusin MV and Nanchuang MV, were investigated. Chemical, physical and petrographic analyses, carbonization tests and coke quality determinations were conducted for these coals. The results showed that these are good quality coking coals and have several properties in common as follows: very high calorific values (> 8000 kcal/kg, d.b.), coking power, vitrinite content (> 94%), Hardgrove grindability index, and coke porosity. They are suitable for coal blending. The coal seams are very thin (≈30–50 cm) and they occur in very young coal-bearing strata (Miocene).     

确定炼焦煤硫转化率方法的研究

根据焦炭中硫为各单种煤中所含硫转化为焦炭中总硫的原理,通过给定的单种煤的硫含量和配煤方案以及焦炭干基全硫的测定值,计算出单种煤的硫转化率,进而用来预测生产焦炭的硫含量。     

Catalytic graphitization of cokes by indigeneous mineral matter

Indigeneous mineral matter in coals acts catalytically towards graphitization during heat treatment of coals to 2273 K. Nineteen coals of a wide range of rank were demineralized by acid extraction. Original and demineralized coals were carbonized in the range 1073–2273 K, and the resulting cokes examined by optical microscopy, X-ray diffraction and phase-contrast high resolution electron microscopy. Optical microscopy indicated the extent of formation of anisotropic carbon in the resultant cokes. The (002) X-ray diffraction profiles indicated three types of catalytic effect, for which electron microscopy demonstrated different crystallite structures and interrelations. The importance of catalytic graphitization in metallurgical cokes in relation to their strength and reactivity is discussed.     

配煤添加高灰低硫及中灰中硫贫煤炼焦的研究

对高灰低硫(新元矿)、中灰中硫(平舒矿)贫煤进行煤质分析和炼焦特性研究,并结合配合煤种进行炼焦和生产验证试验。结果表明,新元矿和平舒矿贫煤适用于捣固工艺,在炼焦中起到瘦化剂的作用,同时能够降低配合煤及焦炭的硫分,改善焦炭的反应后强度。     

Bonding of solid additives in cokes from coals: a microscopy study

Cortonwood Silkstone (NCB class 401) and Betteshanger (NCB class 301 a/204) coals were co-carbonized with solid additives such as anthracite, coke breeze, green and calcined petroleum cokes. The resultant carbonization products (cokes) were examined by optical microscopy and SEM was used to investigate polished surfaces etched by chromic acid and fracture surfaces. For both coals only the anthracite and green petroleum coke become bonded to the coal cokes. This probably results from softening and interaction of interfaces of the anthracite and green coke with the fluid coal via a mechanism of hydrogenating solvolysis during the carbonization process. The coke breeze and calcined petroleum cokes were interlocked into the matrix of coal coke.     

Properties and potential of formed cokes derived from two Turkish lignites by carbonization of binderless briquettes

Two high-sulphur Turkish lignites were briquetted at room temperature under pressures of 113 or 212 MPa and the briquettes were carbonized to 1158–1173 K over special heating cycles. The lower-rank lignite gave a formed coke of superior mechanical strength, lower porosity and higher sulphur content than typical blast furnace cokes. The formed coke produced from the higher-rank lignite briquettes had slightly poorer mechanical strength, lower porosity and much higher ash yield and sulphur content than conventional cokes. The products were considered attractive for use in non-ferrous metallurgy.     

Ultimate analysis of coals and cokes using instrumental techniques

This Paper describes instrumental techniques for the rapid determination of carbon, hydrogen, nitrogen, oxygen and sulphur. Two Perkin-Elmer Model 240 elemental micro-analysers were used, one for the direct determination of oxygen and the other for the simultaneous analysis for carbon, hydrogen and nitrogen. The Leco Automatic Sulphur Titrator was used for the sulphur assay. Accuracy and repeatability similar to that obtained by the classical methods described in the relevant British Standards were found, and data are presented to illustrate the comparison. Special aspects of developed procedures are emphasized which are essential for the attainment of good precision and accuracy.     

炼焦单种煤最佳粉碎粒度研究

为研究炼焦煤在不同粒度下的性质,对肥煤、1/3焦煤、焦煤、贫瘦煤进行了不同筛分粒级的煤岩显微组分及煤质分析,进行了单种煤在不同粉碎粒度下的坩埚焦实验,分析了粒度对焦炭冷热态强度的影响。筛分结果表明:随筛分粒级的减小,镜质组含量增加,惰质组含量减少;灰分主要集中在-1 mm的细粒部分与+10 mm的粗粒部分,硫分主要集中在-1 mm的细粒部分,粒度对煤挥发分影响不大,黏结指数在1～5 mm时优于其它粒级。坩埚焦实验表明:肥煤、1/3焦煤、焦煤等强黏结性煤粉碎到1 mm以下时,热态性能劣化;贫瘦煤配入量多时,细粉碎后没有足够的活性物质包裹惰性组分,焦炭强度急剧下降。     

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。     

改善炼焦工艺管理,扩大炼焦用煤范围

对扩大炼焦用煤煤源的理论基础及可实践应用的新型技术进行了分析和总结,认为从应用新技术和改善炼焦工艺控制入手,可以扩大炼焦用煤煤源。     

焦炭预测系统在邯钢焦化厂的应用

通过小焦炉和铁箱试验对大焦炉质量进行预测,建立了一套比较成熟的焦炭预测模型。该模型对预测大焦炉焦炭质量具有很大的帮助。     

Fundamental research in the European Community on the chemical and physical properties of coal: The European commission's research programme: ‘Chemical and Physical Valorisation of Coal’

On 24 and 25 November 1980, a round table discussion organized by the Commission of the European Communities and attended by coal scientists from six Community countries was held in Brussels. The delegates came from France, the UK, Belgium, the Netherlands, Italy and the Federal Republic of Germany to present and discuss the latest results of their work in the field of fundamental research into the chemical and physical properties of coal. This Letter reports the content of the discussion and describes the reasons for and the significance of this annual meeting.     

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.     

Structure in cokes from coals of different rank

A range of bituminous coals has been carbonized to 1273 K. Polished surfaces of the solid products, carbons or cokes, are examined for optical texture by optical microscopy. Fracture surfaces of the carbons are examined by scanning electron microscopy (SEM). The carbon from the lowest rank coal (NCB Code No. 702) is isotropic and fracture surfaces are featureless. Carbons from coals of ranks 602, 502 are optically isotropic but fracture surfaces are granular (size 0.1–0.2 μm), indicating small growth units of mesophase. In the carbon/coke from a 401 coal, the anisotropic optical texture and grain size are both ≈0.5–10 μm diameter. Coke from a coking coal (301a, 301b) has a layered structure extending in units of at least 20 μm diameter with sub-structures ~ 1.5 μm within the layers, indicating perhaps that the bedding anisotropy of these coals is not totally lost in the fluid phase of carbonization. The carbons from the higher rank coals have the bedding anisotropy of the parent coal. The combined techniques of optical microscopy and SEM (both before and after etching of the fracture surfaces of coke in chromic acid solution) reveal useful detail of structure in carbons/cokes and of the mechanism of carbonization of coking coals.     

Macerals in bituminous coals and the coking process: 2. Coal mass properties and coke mechanical properties

Bituminous coals produced in the Ostrava-Karviná coal basin show considerable variation in their maceral composition, vitrinite reflectance and fluidity. There is a close association of the latter with the $\text{H}\text{O}$ atomic ratio expressing the different chemico-structural properties of vitrinites of lower coalification. These properties of the coal mass all influence the coke mechanical properties; moreover the $\text{H}\text{O}{}_{\mathrm{at}}$ parameter is of principal importance to the course of the coking process. Laboratory, pilot-plant and full-scale experiments show that coals rich in inertinite may give cokes of suitable mechanical properties, providing the $\text{H}\text{O}{}_{\mathrm{at}}$, ratio and the bulk density are high enough. It should be noted, however, that these coals contain finely dispersed inertinite in the vitrinite mass and this may have a positive effect on the coke mechanical properties.