Speciation and thermal transformation of sulfur forms in high-sulfur coal and its utilization in coal-blending coking process:A review

The utilization of high-sulfur coal is becoming more urgent due to the excessive utilization of low-sulfur,high-quality coal resources,and sulfur removal from high-sulfur coal is the most important issue.This paper reviews the speciation,forms and distribution of sulfur in coal,the sulfur removal from raw coal,the thermal transformation of sulfur during coal pyrolysis,and the sulfur regulation during coal-blending coking of high organic-sulfur coals.It was suggested that the proper characterization of sulfur in coal cannot be obtained only by either chemical method or instrumental characterization,which raises the need of a combination of current or newly adopted characterization methods.Different from the removal of inorganic sulfur from coal,the organic sulfur can only be partly removed by chemical technologies;and the coal structure and property,particularly high-sulfur coking coals which have caking ability,may be altered and affected by the pretreatment processes.Based on the interactions among the sulfur radicals,sulfur-containing and hydrogen-containing fragments during coal pyrolysis and the reactions with minerals or nascent char,regulating the sulfur transformation behavior in the process of thermal conversion is the most effective way to utilize high organic-sulfur coals in the coke-making industry.An in-situ regulation approach of sulfur transformation during coal-blending coking has been suggested.That is,the high volatile coals with an appropriate releasing temperature range of CH4 overlapping well with that of H2 S from high organic-sulfur coals is blended with high organic-sulfur coals,and the C–S/C–C bonds in some sulfur forms are catalytically broken and immediately hydrogenated by the hydrogencontaining radicals generated from high volatile coals.Wherein,the effect of mass transfer on sulfur regulation during the coking process should be considered for the larger-scale coking tests through optimizing the ratios of different coals in the coal blend.

Preparation of CaO-containing carbon pellets from coking coal and calcium oxide:Effects of temperature,pore distribution and carbon structure on compressive strength in pyrolysis furnace

CaO-containing carbon pellets(CCCP)were successfully prepared from well-mixed coking coal(CC)and calcium oxide(CaO)and roasted at different pyrolysis temperatures.The effects of temperature,pore distribution,and carbon structure on the compressive strength of CCCP was investigated in a pyrolysis furnace(350-750℃).The results showed that as the roasting temperature increased,the compressive strength also increased and furthermore,structural defects and imperfections in the carbon crystallites were gradually eliminated to form more organized char structures,thus forming high-ordered CC.Notably,the CCCP preheated at 750℃exhibited the highest compressive strength.A positive relationship between the compressive strength and pore-size homogeneity was established.A linear relationship between the com-pressive strength of the CCCP and the average stack height of CC was observed.Additionally,a four-stage caking mechanism was developed.

Preparation and performance analysis of a coking coal dust suppressant spray

Coking coal dust is extremely hydrophobic;therefore,combination with droplets in the air is difficult and dust suppression is challenging.Here,a dust suppressant spray for coking coal dust was studied in order to improve of the combination of droplets and coking coal dust.Based on monomer optimization and compounding analysis,two surfactant monomers,fatty alcohol ether sodium sulfate(AES)and sodium dodecyl benzene sulfonate(SDBS)were selected as the surfactant components of the dust suppressant.The surfactant monomers were combined with four inorganic salts and the reverse osmosis moisture absorption of each solution was determined.By combining the reverse osmosis moisture absorption values with the water retention experimental results,CaCl_(2)was identified as the optimal inorganic salt additive for the dust suppressant.Finally,the optimal concentration of each component was obtained using orthogonal experimental design i.e.,AES(0.03%),SDBS(0.05%),and CaCl_(2)(0.4%).The dust suppressant solution formulated using this method had a high moisture absorption capacity and excellent performance.

Disposal of Waste Plastics With Traditional Coking Process

A new technology for treating waste plastics （WP） by traditional coking process was introduced. With a thermo-balance and a 10 g atmospheric fixed bed reactor, the thermo-gravimetric behavior and product were studied during co-coking of WP with blended coal. And then, using a coke-oven with capacity of 200 kg, the characteristics of products were assessed. The results showed that there is an overlapping temperature range （200-550℃ ） of decomposition between WP and blended coal, and the pyrolysis synergism index η and synergism strength β proposed could evaluate the synergism between them. 1% of added WP results in the maximum synergism in all series experiments. The increase of added WP decreases the synergism. Tar yield in co-coking is increased with the decrease of water yield for synergism. Moreover, it was also found that the quality indexes of coke, such as M10, M40, CRI and CSR, are degraded with the increase of WP until 4%, though the quality of tar and gas is optimized for WP addition.

RESEARCH ON THE QUALITY PRICE RATIO OF COKING COAL

If assortment priee parity of Clase coking coal and its qtalty price danrcnee is nonreasonable, it deren’t gulde in Anprotrig tbe quallry metaliurgical coking coal and may be influence theeconomic benefit of metallurgical enterprises. This paper propose the principles and mathematicmodel for determination aseortment party of clean cokingcoal and its quality difference of ash content in clean coking coal in order to urge wasbenes into producing superior clean coking cleal whichis under condition of consideration both interest waskeries and interest metallurgicai industry. It canbe used as a method in theory to make price strategies under condition of socialism maket economicfor washeries of clean coking

Effect of Indian Medium Coking Coal on Coke Quality in Non-recovery Stamp Charged Coke Oven

The maximum possibility of utilizing the Indian coking coals and inferior grade coking coal for producing metallurgical coke through non-recovery stamp charging tech_nology was investigated. Indian indigenous coals contained low percent of vitrinite （〈50%） and higher content of ash （〉15%） compared to imported coking coal. Therefore, the selection of appropriate proportion of different types of coals was a major challenge for coke makers. Coal blend selection criterion based on a single coefficient, named as composite coking potential （CCP）, was developed. The use of increased proportion of semi-soft coal （crucible swelling number of 2.5） and high ash （≥15%） indigenous coal in the range of 20%- 35% and 20%-65% respectively in the blends resulted in good quality of coke. Plant data of a non recovery coke oven were used for developing and validating the model. The results showed that the coke strength after reaction （CSR） varied in the range of 63.7%-67.7% and the M40 value was between 81.8 and 89.3 in both the cases.

Preparation and coking properties of coal maceral concentrates

The concentrates with different maceral contents were obtained from Kailuan coking coals with different coal ranks(Ro;ranvarying from 0.88%to 1.73%)by float–sink separation in lab.Then these concentrates were characterized by proximate analysis,ultimate analysis,petrography analysis and coking index determination.The results show that the vitrinite is characterized as nature of lower carbon content,higher hydrogen content,higher volatile matter and stronger caking property compared to inertinite.The relationships between variation rate of volatile matter and maximum volatile matter and coal ranks are identified,and a linear model is developed for fast determination of the maceral contents.Compared to inertinite-rich concentrate,the blending ratio of vitrinite-rich concentrate is increased by 13%,which is considered to be a potential technique based on maceral separation for expanding the coking coal resources.

Coking Properties of Tavantolgoi Coal from Mongolia

Main technical and structural characteristics of Tavantolgoi coal from Mongolia are determined. Type, code number and other valuable technological indexes of the coal are estimated according to the international classification system of coals. Cokes obtained in a laboratory chamber stove and in a reactor was characterized.

COMPARING STUDY OF BLENDING PREHEATING MODIFIED COAL COKING AND STAMPING COKING FOR DONGSHEN COAL

The compaison of the properties of coke of three coking methods is introduced. The mechanical properties and high temperature reactivity of coke bleding preheating modified Dongshen coal are improved obviously than those of normal coke, and achieve or exceed that of stamping coke. This method shows more ability of expending coking coal resources.

Purification process of coal-based coke powder as anode for Li-ion batteries

A process of purification of coal-based coke powder as anode for Li-ion batteries was attempted. The process started with the treatment of coke powder with dilute hydrofluoric acid solution, followed by united-acid-leaching using sulfuric acid and hydrochloric acid. The effects of altering the hydrofluoric acid addition, hydrofluoric acid concentration, contact time, temperature and acid type were investigated. A minimum ash content of 0.35% was obtained when proper conditions were applied. The electrochemical performance of purified coke powder shows greatly improved electrochemical performance. The as-purified coke powder presented an initial reversible capacity of 257.4 mAh/g and a retention rate of 95% after 50 cycles. The proposed purification process paves a way to prepare a promising anode material with good performance with low cost of coke powder for Li-ion batteries.

Technology for Coking of Heavy Crude Oil with High Acid Number

Sudan Khartoum Refinery Co. has selected a unique route featuring delayed coking of crude in connection with the highly sour and high-calcium heavy crude extracted from Sudanese oil block No. 6.The crude oil after pretreatment for calcium removal is subjected to coking for removal of acids and metals with the coker products being further processed. The crude oil extracted from Sudanese oil block No. 6contains as high as 13 mg KOH/g of crude in addition to a calcium content of 1600 ppm. This article makes an analysis on problems related with the operation of commercial delayed coking unit for processing of highly sour crude and bring forth measures to solve these problems. The liquid yield resulted from coking of crude oil can reach 82m%, and the petroleum coke can meet the quality requirement for class 3B petroleum coke.

Characterization of semi-coke generated by coal-based direct reduction process of siderite

Solid wastes derived from metallurgical industries pose a significant threat to environment. The utilization and disposal of these solid wastes are the major concern in the world. Semi-coke generated in coal-based direct reduction process of iron ore is a by-product and its suitable utilization is not available so far. In order to handle it properly, the characteristics of this by-product were comprehensively investigated. A series of analysis methods were used to demonstrate its mineral compositions, petrography and physico-chemical properties. The results reveal that the semi-coke has poor washability. The fixed carbon content of semi-coke reaches 76.11% and the gross calorific value is 28.10 MJ/kg, both of which are similar to those of traditional sinter coke breeze. Also, semi-coke ash possesses lower content of SiO2, Al2O3, S and higher content of CaO and MgO, which could improve the strength of sinter ore when partially substituting for coke breeze in sintering. Semi-coke features well-development porous structure and higher reaction activity, which predicts that the sintering speed could be elevated to some extent when employing it as a partial replacement of coke breeze, so the studies further suggest that the potential adverse effect of the high reactivity on sintering process could be weakened by adequately coarsening the semi-coke's particle size.

高炉喷吹用烟煤配煤炼焦试验研究

为了扩大炼焦煤资源,优化配煤结构,结合烟煤配煤炼焦理论,通过高炉喷吹用烟煤的工业铁桶试验研究,分析了配加烟煤后配合煤的性能变化和所炼焦炭的质量。结果表明:适当增加1/3焦煤、减少气煤配比,烟煤配加质量分数控制在2%~3%,可以有效优化配煤结构,使配合煤的灰分、硫分及挥发分保持在稳定状态,改善焦炭的机械强度、热强度,提高焦炭的块度,同时还可以降低配煤成本,当烟煤配加质量分数为2%时,配煤成本可降低15.60元/t。

燃用高碱煤锅炉受热面结焦及其防治研究概述

以准东煤为代表的高碱煤虽储量巨大,但火电机组掺烧高碱煤过程中造成锅炉受热面结焦问题突出,不仅降低锅炉热效率,而且严重威胁机组安全、稳定、经济运行。为解决结焦技术难题,促进高碱煤掺烧利用,对燃用高碱煤锅炉受热面结焦及其防治研究进行了综述。截至目前,国内外围绕燃煤锅炉受热面结焦特征、结焦机理、影响因素、防治措施等已经开展了广泛研究并取得了丰硕的研究成果。在控制燃煤质量、改善锅炉结构、优化锅炉运行等措施基础上,在锅炉受热面制备涂层成为防治结焦的重要技术途径。在未来研究过程中,涂层在具备突出抗结焦性能的同时,须兼具优良的耐高温、抗腐蚀、耐磨损、导热性、热疲劳等综合性能,且具有良好的制备经济性、制备效率,特别是现场适用性。

酸化后焦煤表面性和孔隙性变化对吸附热的影响

目的为了探究酸化后焦煤的表面性和孔隙性变化对其吸附热的影响,方法选取山西古交矿区焦煤为研究对象,利用盐酸(HCl)和氢氟酸(HF)酸化处理,采用接触角法、低温液氮吸附法和微量热法等测试方法,对比分析了酸化前后焦煤的煤-水接触角、表面张力、孔隙结构等变化,并探讨了这些变化对吸附热的影响机制。结果酸化后焦煤的平均煤-水接触角由75.10°增至80.11°,平均表面张力由44.44 mJ/m^(2)减至39.48 mJ/m^(2),亲水性减弱;酸化后焦煤的总孔容、中孔孔容、比表面积和平均孔径均增大,而微孔和大孔的孔容及比表面积均减小,表明矿物质脱除有利于微孔向中孔转化;同等压力下,随着温度升高,分子热运动加强,分子能量突破固体表面势垒,气体分子成为游离态,导致原煤和脱灰煤的积分吸附热和微分吸附热减小,且脱灰煤的吸附热高于原煤的。结论矿物质会减弱焦煤对气体的吸附能力,且占据焦煤表面的吸附位。因此,酸化后矿物质的脱除导致焦煤表面的吸附位增加,是引起吸附热增大的主要原因。

炼焦煤热解过程中膨胀压力的形成机制及对焦炭质量的影响

在工业室式炼焦过程中,膨胀压力过高会造成焦炉炉墙损坏及推焦困难,膨胀压力过低会影响焦炭产品质量。现行焦化工艺通过调节入炉煤挥发分控制膨胀压力,缺乏对炼焦煤膨胀压力形成机制的本质认识,可能导致焦炉运行不稳定、焦炭质量波动大等问题。基于此,通过分析炼焦煤结构特性,从分子水平探究了膨胀压力的形成及演变,并揭示了炼焦煤膨胀性与焦炭质量的本质联系。利用核磁共振碳谱(^(13)C NMR)分析了五种不同煤阶的炼焦煤(Q1,JA1,F1,J1和S1)的化学结构。通过热重分析(TGA)、小型热解实验等方法以及基式流动度测定仪、奥亚膨胀仪、透气性在线检测装置及膨胀压力和膨胀位移检测装置等仪器探究了单种煤热解过程中煤基体分解行为、流动特性和膨胀特性的演化机制。结果表明:热解气体CO,CO_(2),CH4的释放和低透气性带的形成影响了膨胀压力的产生,适宜的膨胀压力可提高焦炭质量;300℃~450℃是煤产生膨胀压力的温区,与煤中f_(al)^(O1),f_(al)^(O2)和f_(al)^(1)~f_(al)^(5)结构的分解有关;膨胀压力过高(120 kPa~180 kPa)的煤,形成的焦炭孔隙多、真密度小,质量差;膨胀压力适中(90 kPa~120 kPa)的煤,形成的焦炭质量较好。

煤液化残渣诱导缩聚制备冶金焦的影响因素

煤液化残渣所含沥青质和重油在热解时可产生大量自由基,如不能被及时稳定和缩聚将转化为大量焦油和气体,形成孔隙结构,从而影响所制冶金焦密度。为此,拟引入添加剂诱导其高效缩聚,提高聚合物密度,再经炭化后制备优质冶金焦。通过系统研究不同添加剂(糠醛、甲醇、呋喃和羟基丙酮)、温度(350、400、450、500和550℃)、停留时间(0、30、60和120 min)和添加量(0、4、8和16 g)对所制聚合物缩聚率、结构性质、密度、热稳定性和表面性质影响,获得煤液化残渣诱导缩聚的最优试验条件。在最优条件下,分别探讨所制聚合物和炭化物的表面形貌、微晶结构和元素变化情况,获得煤液化残渣诱导缩聚机理。结果表明,添加剂(糠醛)的诱导缩聚效果最佳,其次是羟基丙酮,因而理想添加剂至少应含有1个醛基或酮基。不同添加剂可促进煤液化残渣缩聚,提高所制聚合物比表面积、孔容、平均孔径和真密度。温度和停留时间对煤液化残渣/糠醛聚合物热稳定性和表面性质影响较大,温度升高和停留时间延长可促进煤液化残渣所含酚类基团和芳香物中H参与缩聚反应,提高聚合物的缩聚程度。煤液化残渣/糠醛(焦炭)整体呈片层密实状,并含更多无定形碳。

天然焦内炭微球显微光学特征、成因及其意义

天然焦内炭微球是煤层遭受岩浆速热变质的产物,其显微光学特征成因解析有助于深入认识煤速热碳化和热变质。采集安徽淮北石台煤矿富含炭微球的天然焦样品,利用高分辨率反射偏光显微镜和扫描电镜等实验手段,表征了天然焦中炭微球的粒度、分布、显微光学和超微组构特征,以揭示其光学各向异性的成因和热演化意义。结果显示,远离岩体天然焦中炭微球以粗粒为主,粒径10~100μm,少数可达150μm以上;紧邻岩体天然焦炭微球以细粒为主,粒径1~10μm,在岩体内脉状焦内甚至低至1μm以下。分析显示,粗粒炭微球和炭半球分别发育“十字”消光和“波状”消光,是其内部放射状一轴晶光率体在切面内投影的光学表征;细粒炭微球发育“十字-双曲线”消光,是其内部放射排布的二轴晶光率体切片投影的旋转效应。由此可见,趋近岩体,伴随着镜质体反射率增加,煤焦光率体逐渐由规则球形(光性均质体),向二轴椭球体(一轴晶)和三轴椭球体(二轴晶)转变。在该过程中,“十字”消光和“波状”消光的粗粒炭微球是煤热脱挥发分的产物,而“十字-双曲线”消光的细粒炭微球是煤热缩聚而片层化的标志。天然焦中炭微球的显微光学特征是煤层趋热碳化的结果,本质上是其光率体受热变形的光学表征,可有效评价岩浆蚀变煤焦的热变质程度。

生物炭替代煤粉/焦炭高炉炼铁碳减排技术研究进展

钢铁行业是能源消耗和碳排放大户,因此在碳中和背景下寻求可替代传统煤的零碳原料是钢铁行业重点发展的碳减排技术。生物炭具有碳中性特征,碳含量和热值与煤接近,是煤粉和焦炭理想的替代原料。本文系统介绍了生物炭在炼焦、烧结、高炉炼铁中的潜在利用途径,并进一步聚焦生物炭应用于高炉炼铁时所需具备的理化特性,阐述了生物炭碱金属、强度、粒度与比表面积在替煤代焦时的影响及机理。针对碱金属降低焦炭强度等问题,介绍了酸洗等脱矿方法降低生物炭碱金属含量;针对生物炭机械强度差难以入炉问题,总结了焦炭强度形成机理和生物炭成型增强工艺;针对生物炭导致炼焦煤混合物流动性变差问题,通过调控生物炭粒度和比表面积以降低对焦炭的负面影响。最后,总结了生物炭替代煤粉和焦炭高炉炼铁的国内外进展及预期CO_(2)减排效果。通过分析生物炭替煤代焦目前工业应用中存在的挑战以及生命周期评价的相关研究情况,为未来钢铁行业实现碳中和提供技术支撑。