Modification of sub-bituminous coal by steam treatment: Caking and coking properties

A Chinese sub-bituminous Shenfu (SF) coal was steam treated under atmospheric pressure and the caking and coking properties of the treated coals were evaluated by caking indexes (G_RI) and crucible coking characterizations. The results show that steam treatment can obviously increase the G_RI of SF coal. When the steam treated coals were used in the coal blends instead of SF raw coal, the micro-strength index (MSI) and particle coke strength after reaction (PSR) of the coke increased, and particle coke reactivity index (PRI) decreased, which are beneficial for metallurgical coke to increase the gas permeability in blast furnace. The quality of the coke obtained from 8% of 200 °C steam treated SF coal in coal blends gets to that of the coke obtained from the standard coal blends, in which there was no SF coal addition in the coal blends. The removal of oxygen groups, especially hydroxyl group thus favoring the breakage of the coal macromolecules and allowing the treated coal formation of much more amount of hydrocarbons, may be responsible for the modified results. The mechanism of the steam treatment was proposed based on the elemental analysis, thermo gravimetric (TG) and FTIR spectrometer characterizations of the steam treated coal.     

Effect of coal soluble constituents on caking property of coal

Three cokemaking bituminous coals were extracted by the CS₂/NMP mixed solvents with different content of NMP, and the effect of the amount and the component of coal soluble constituents on the caking property of the extracted residues of coals were investigated in this study. The CS₂/NMP mixed solvent (1:1 by volume) was found to give the maximal extraction yields for the three coals, and the fat coal gave the highest extraction yield of 78.6% (daf) corresponding to its highest caking index of 101. It was found that for coking coal, when the extraction yield got to the maximum of 25.3% in the 1:1 by volume of CS₂/NMP mixed solvent, the residue extracted still had caking property with the caking index of 19. This means parts of the caking constituents of coal are un-extractible because of covalent bonding or strong associative cross-links. The soluble components extracted by the CS₂/NMP mixed solvent and their effects on the caking indexes of the residues at a similar extraction yield quite differed depending on the NMP content in the mixed solvent. The coal solubles extracted by the CS₂/NMP mixed solvent with NMP less than 50% contained less light constituents with less of oxygen groups. This may lead to the decrease in the caking indexes for the residues obtained at the similar extraction yields compared to those of the CS₂/NMP mixed solvent with NMP more than 50%.     

配合煤配比对焦炭综合热性质的影响

以企业生产实践为背景,研究在配合煤中增配肥煤和1/3焦煤对焦炭综合热性质的影响。对不同配比配合煤的性质指标进行检测,采用40 kg焦炉实施炼焦试验,并对炼制焦炭的传统国家标准热性质指标和利用自主研制装置测得的综合热性质指标进行测定。结果表明:增配肥煤和1/3焦煤,均会使配合煤的变质程度降低,挥发分含量升高,胶质体的黏结能力下降,但胶质体的量保持不变。配比变化引起的配合煤性质指标的变化没有显现在焦炭的传统国家标准热性质指标反应性CRI和反应后强度CSR上。以往的研究都是以CRI和CSR指标为目标量判断配合煤的配比是否合适,本研究除此之外还采用了自主提出的焦炭综合热性质指标。配合煤配比变化引起的焦炭的综合热性质指标变化比国家标准热性质CRI和CSR指标变化敏感,这可能与其反映了焦炭某些新的特征有关。基于焦炭综合热性质指标的变化规律,考虑到1/3焦煤具有经济性,生产上增配某些特定的1/3焦煤,可以同时达到提高焦炭质量和降低配煤成本的目的。     

炼焦精煤氧化性质的研究

测试了5种露天堆放的炼焦煤在不同时间的各指标变化情况,结果表明：高挥发分高粘结性的炼焦煤在氧化初期结焦性略有上升,然后逐步下降;中等及低挥发分的炼焦煤随着煤质的氧化其结焦性越来越差;煤的挥发分随堆放时间延长而下降,灰分则略有上升。     

Statistical analyses and prediction of coking properties of coal

Using regression analyses between the properties of coals and the strengths of their cokes several significant correlations are derived, which are useful to evaluate coals in the making of metallurgical coke. Slight but significant modification was necessary for their application to coal blends. For example, plasticities of the coal blends required a different equation from that derived for the single coals. The region of high coke-strength in the diagram of volatile matter vs. total dilatation was expanded considerably towards coals of lower caking properties by blending of coals, suggesting that the blending may serve to increase the coking properties of component coals. The coke strength, especially after the gasification was found to increase with the increasing inert maceral content in the parent coals up to 30 wt %. The high level of strength was maintained even above 35 wt % of inert content.     

单种强黏结性肥煤的配煤实验及黏结指数变化分析

将半焦、焦粉、主焦煤以不同的比例,配入新疆焦煤集团强黏结性肥煤中,进行黏结性实验,实验结果表明,焦煤和经低温干馏处理过的半焦在配入比例5%以内时,配合煤的黏结指数并未遵循低于最高黏结指数的一般规律;不同温度干馏的半焦其配合煤的黏结指数不同。通过实验验证,强黏结性的肥煤对无黏结性的半焦会产生非常强的黏结性,这对于动力煤的半焦的配煤炼焦具有一定的实践意义。     

美国与俄罗斯瘦焦煤的煤质分析及应用

通过对美国Buchanan矿和Windber矿以及俄罗斯K10三种瘦焦煤煤质对比分析,可知3种瘦焦煤普遍具有较强的结焦性,单独炼焦均可形成较好的焦炭组织,在保持焦炭强度基本稳定的情况下,可以替代一部分国内的焦煤。并简要介绍了沙钢焦化厂近年来配用该三种瘦焦煤的情况,使用这三种瘦焦煤,可以降低配合煤成本。     

不同煤阶煤的CS2-NMP萃取率及与煤性质的关联

对6种不同变质程度煤(包括气煤、弱黏煤、肥煤、焦煤和瘦煤)常温常压下用CS2-NMP混合溶剂进行了萃取实验.结果表明,挥发分(Vdaf)为35%左右的煤具有最高的萃取率,达到43.05%,不同煤阶煤的萃取率与其奥压膨胀度及塑性温度区间近似呈线性关系.通过对原煤、萃取残渣和生成焦粒的红外对比分析表明,不同变质程度煤经过萃取后,残渣中脂肪烃和脂环烃含量有所减少,矿物质大都在残渣中,氢键缔合峰的强弱随不同煤种表现不同,肥煤和气煤氢键缔合的极性键都位于煤中的大分子上,而焦煤和弱黏煤中的极性键大都在小分子化合物上.     

石油焦配煤炼焦试验研究

通过对石油焦的特性研究及配煤炼焦试验,考察其对配煤黏结性能及焦炭质量的影响,研究结果表明,添加石油焦会引起煤的黏结指数下降,加入石油焦配煤炼焦会降低焦炭灰分,提高焦炭硫分,降低焦炭冷强度,提高焦炭热强度。     

Solvent-refined coal from high-ash non-coking coals and washery middlings for use in metallurgical coke making Part 1. Production,testing and characterisation

This paper presents studies on the preparation of a potential coking additive, solvent-refined coal (SRC), from typical high-ash Indian non-coking bituminous coals, tertiary Assam coal with a high sulphur content and washery middlings in a bench-scale unit (10 kg h⁻¹ coal throughput capacity) under hydrogen pressure. The extraction of the coal samples was conducted under moderate reaction conditions of temperature, pressure and residence time. No external catalyst was used in the process. Pre-beneficiated coal was used as the feed material and anthracene oil with a boiling range of 270–360°C was used as the solvent. Rigorous solid separation from the extract slurry by filtration was avoided by centrifugation in a super-decanter centrifuge to produce SRC with an ash content of 6–7%. The yield of SRC from non-coking Samla seam coal of the Raniganj coalfield was found to be 85% while its caking index was 44. Substantial improvement in the quality of blast furnace-grade coke was achieved by co-carbonisation of coking blends by mixing only 10% of the SRC prepared from Assam coal. The hydrogen requirement was low (1.5% wt/wt of d.a.f. coal) and recovery was of the order of 96% of the solvent used for the preparation of the coal-oil slurry. The yield of SRC and its quality as a coking agent are reported, along with the quality of the coke produced using SRC obtained from typical coal.     

Carbonization of coal blends: mesophase formation and coke properties

Laboratory investigations of strength of cokes from blends of coals incorporating pitch were supported by 7 kg trials. The stronger cokes showed a greater interaction between coal and pitch to produce an interface component of anisotropic mozaics which is relatively resistant to crack propagation. The process whereby coal is transformed into coke includes the formation of a fluid zone in which develop nematic liquid crystals and anisotropic carbon which is an essential component of metallurgical coke. Strength, thermal and oxidation resistance of coke can be discussed in terms of the size and shape of the anisotropic carbon which constitutes the optical texture of pore-wall material of coke. Coals of different rank form cokes with different optical textures. Blending procedures of non-caking, caking and coking coals involve the interactions of components of the blend to form mesophase and optical texture. Petroleum pitches used as additives are effective in modifying the carbonization process because of an ability to participate in hydrogen transfer reactions.     

两种肥煤的黏结性研究

在室温下用CS2/NMP对两种肥煤进行超声波抽提实验,考察了溶剂混合比例对肥煤抽提和抽余物黏结性能的影响。研究结果表明,新疆艾维沟肥煤比枣洗肥煤的缔合结构强,黏结组分主要缔合在煤的大分子结构内部,其分子量分布适中,具有较好的黏结性能。     

基氏流动度在配煤炼焦中的应用

针对迁安中化炼焦煤采用常规煤质指标分析出现的单种煤常规指标较好,配煤炼焦后焦炭强度下降的问题,采用基氏流动度分析了常用两种中强黏结性炼焦煤A煤和B煤的煤质,探讨了其与常规煤质指标的关系,介绍了基氏流动度在配煤炼焦中的应用情况及存在问题。结果发现,A煤和B煤的常规煤质指标接近,最大基氏流动度分别为7209 ddpm和829 ddpm,可以较好区分两种煤;基氏流动度特征指标中的软化温度、塑性温度区间及最大流动度可反映炼焦煤的基本性质;炼焦煤的最大流动度的对数值在2.2~3.0、挥发分在23%~27%时,焦炭M40>87%、M10<7%。     

山东地区1/3焦煤容惰能力研究

通过引用黏结指数测试法,对山东地区1/3焦煤与气煤、气肥煤和其他地区1/3焦煤的容惰能力进行比较。结果表明,炼焦煤的容惰能力不仅与变质程度,也与工艺性质相关;在本实验分析煤样中,新汶气肥煤容惰能力最强,黄陵气煤容惰能力最差,山东付村1/3焦煤的容惰能力比其他地区高G值1/3焦煤微弱,山东蒋庄、润峰1/3焦煤的容惰能力比河市坝等低G值1/3焦煤弱,但高于气煤。     

东庞煤矿高硫煤配煤炼焦的研究与应用

东庞煤矿9号煤资源丰富,为高硫气肥煤和肥煤,黏结性很好,适当降硫就可用于炼焦配煤,此品种在周边用户群中有一定的需求。通过对东庞矿区的2号煤和9号煤进行配煤、煤质分析、40 kg焦炉炼焦实验等,研究配煤指标变化和成焦性能。镜质组最大反射率实验结果表明：配煤具有煤种的单一性,其工业性质及黏结性等指标具有近似的数学加权性,通过配煤入洗可以实现高低硫资源煤质指标互补。将研究成果用于指导实际生产,改造东庞矿洗煤工艺,新建东庞矿西庞井选煤厂,实现高硫煤的全部配煤入洗,生产出满足市场需求的中高硫气肥煤品种,扩大了炼焦资源和高硫煤用途,提高了企业经济效益。2011年生产高硫精煤111万t,直接增加收入1.5亿元。     

单一炼焦煤煤岩性质对黏结性和结焦性的影响

对不同变质程度单种煤的煤岩性质以及对应的40kg试验焦炉所炼焦炭的性质进行测定和分析表明,单种煤的黏结性不仅受煤变质程度影响,而且受炼焦煤中煤岩组成的影响,单种煤的镜质组平均最大反射率在1.1%左右时,煤的黏结性最好;镜质组反射率分布在1.1%~1.3%所占比例为30%左右时,所得焦炭的M40和M10最好。     

A laboratory scale assessment of the utilization potentials of sub-bituminous Nigerian coals as components of coking blends

This paper examines the ability of A240 Petroleum pitch to improve the coking characteristics of sub-bituminous Lafia and Enugu coals of Nigeria. Also examined is the compatibility of Enugu and Lafia coals with a prime coking Ogmore coal in a blend for coke making. The exercise is motivated by the desire to include non-coking Nigerian coals in coal blends for making blast furnace coke.The coking characteristics of Lafia and Enugu coals are highly susceptible to improvement by A240 petroleum pitch. The pitch also interacts with the improves the coking characteristics of a blend of Enugu and Lafia coals.No interaction occurs between Enugu and Ogmore coals. Little interaction occurs between Lafia and Enugu coals. A strong interaction occurs between Lafia and Ogmore coals. Ogmore coking coal tremendously improves the coking characteristics of a blend of Lafia Enugu coals. Optical microscopy, microstrength and reactivity tests reveal that high volatile coking Lafia coal act as a bridging coal between Enugu coal and a prime coking coal in a ternary coking blend.     

唐钢炼焦肥煤和瘦煤应用浅析

通过40kg试验焦炉对唐钢肥煤、瘦煤资源进行优化配比,找出不同质量肥煤和瘦煤配合结焦规律以及对焦炭强度指标的影响,从而确定肥煤、瘦煤最佳配比:肥煤38%,焦煤37%,1/3焦煤12%,瘦煤13%。实际生产后,焦炭强度M40由原来的80.4%上升到81.0%。     

6m焦炉配煤方案的优化与完善

为稳定改善6m焦炉焦炭质量,以20kg小焦炉试验、岩相检测、焦炭反应性和反应后强度检测为主要试验手段,对现用气煤、1/3焦煤、焦煤、低硫肥煤、高硫肥煤、瘦煤等煤种作了配煤炼焦试验,优化了配煤结构。并从经济效益出发,在保证焦炭强度的条件下,提高了气肥煤配量,进一步优化完善了6m焦炉的用煤结构,年新增效益700多万元。     

炼焦煤焦化特性评价指标探讨

介绍了奥亚膨胀度、基氏流动度、罗加指数、胶质层指数、黏结指数和镜质组平均最大反射率等冶金煤焦化特性评价指标的建立和测试方法,以及各评价指标在我国的应用情况。同时讨论了各个指标对胶质体的原生黏结性、膨胀程度引起的黏着性和焦炭残留物强度这3个焦化特性的表征。