焦炭反应性及反应后强度影响因素及预测模型的研究

通过40 kg试验焦炉炼焦试验,从胶质层及中间相理论入手,通过进行动力学分析,找出了对焦炭反应性(CRI)及反应后强度(CSR)的影响因素,对煤的各性质参数进行了筛选和简化,尝试建立了焦炭CRI、CSR的预测模型。结果表明:影响焦炭CRI及CSR的首要因素是煤的变质程度;K和Ca对焦炭的反应性有明显的催化作用,其中,K的催化作用是Ca的18倍;CRI与CSR有显著的负相关关系,CSR受煤的粘结指数(G)的影响较大;该研究可用于指导炼焦配煤生产。活性组分与惰性组分含量与△T有关,对G值也会产生较大的影响。     

不同煤阶煤焦炭显微结构与热性质的研究

采用模拟焦炭反应性和反应后强度,研究了不同变质程度单种煤焦炭显微结构与热性质之间的关系。中等变质阶段的焦煤、肥煤和瘦煤所制焦炭有较高的各向异性,低变质程度的气煤、1/3焦煤以及高变质程度的贫煤所制焦炭各向异性程度较低。焦炭的热性质与焦炭的各向异性有很好的相关性,焦炭反应性随各向异性程度的增大而减小,反应后强度则随各向异性的增大而增大。     

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。     

主焦煤配入比例对焦炭热反应性的影响

在40kg焦炉上进行了多方案的配煤炼焦试验,并对单种煤及配合煤炼焦的焦炭热反应性进行了分析,结果表明,单种焦煤炼焦时25JM的反应后强度最好;配合煤中控制主焦煤的配入比例,适当配入14SM、1／2ZN或26FM后,焦炭的热反应性比单种焦煤炼焦的效果好。     

不同类型焦炭光学组织与CO_2反应性关系的研究

以不同配煤方案配合煤所炼焦炭为研究对象,测定了焦炭的光学组织组成、焦炭反应性CRI和反应后强度CSR,利用多元线性回归的方法找出不同光学组织组成与焦炭热性质的关系;同时测定了焦炭与CO_2反应后焦样的光学组织组成,并定量计算了不同类型焦炭光学组织与CO_2反应性的关系。研究结果表明,不同类型焦炭光学组织与CO_2反应性存在较大的差别,即各向同性、丝炭与破片、细粒镶嵌、片状、完全纤维、不完全纤维、中粒镶嵌、粗粒镶嵌与CO_2相对反应性的大小为:9.3、8.5、6.2、5.4、2.6、1.5、1.3、1。     

日本开发高反应性焦炭

研究表明,与CO2反应性好的高反应性焦炭作为烧结矿的还原材料使用,可降低高炉化学保存带的温度。另外,在普通的配合煤中配入碳酸钙含量高的煤,生产高反应性焦炭,在高炉中试用的结     

影响焦炭热态性质的因素探讨

对皖北17种煤样进行了性质分析及40kg小焦炉炼焦试验,结果表明,灰分中的碱性氧化物对焦炭的溶损反应起着正催化作用,其含量越大,焦炭的反应性越大;挥发分含量在20%～24%、镜质组反射率在1.3～1.8之间的煤,焦炭的反应性和反应后强度较好;硫的存在能抑制焦炭的CO2反应性,随着硫含量的增高,焦炭的反应后强度有所提高.建立的预测模型具有一定的可靠性与稳定性.     

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。     

不同粒级的焦煤和肥煤其性质研究

焦煤和肥煤是优质的炼焦煤资源,为研究焦煤和肥煤粒级变化对焦炭质量的影响,对几种焦煤和肥煤五个粒级(13mm、 13～6mm、6～3mm、3～0.5mm、0.5mm)的煤样进行了煤质指标分析,并研究了焦煤和肥煤不同粒级其坩埚焦的热性质。实验结果表明,随着焦煤和肥煤粒级的增大,挥发分含量和镜质组含量减少,惰质组含量增加。肥煤和焦煤在粒级0.5mm和13mm时,灰分含量最高。同一煤种不同筛分粒级煤样的黏结性和结焦性指标存在差异,煤样粒级在3～0.5mm时,焦煤和肥煤的黏结指数G、奥阿膨胀度b值及总膨胀度(a+b)以及胶质层最大厚度Y值达到最大。3～0.5mm粒级煤样所炼坩埚焦其反应性(PRI)最低,反应后强度(PSR)最高。     

神东矿区高挥发分喷吹煤粉对焦炭缓熔性能的影响研究

以神东矿区高挥发分烟煤为对象,研究高炉喷吹煤粉对焦炭缓熔性能的影响规律。结果发现,神东喷吹煤具有低灰、低硫、高发热量、高化学反应活性、低磷含量、低钾钠含量等优点,是优良的喷煤配煤;其干馏煤粉反应活性高于冶金焦炭,加入后可降低不同性能焦炭的热反应性（CRI）和反应后强度（CSR）的差别,且对使用性能较差的焦炭的效果更好;加入该干馏煤粉后,焦炭与CO2的反应可分为三个阶段,干馏煤粉的存在减缓了焦炭的熔损反应,有利于保持焦炭在高炉中的作用,因而在高炉风口回旋区保留一定量的未燃煤粉是有益的。     

Coal rank and coke reactivity

For a series of cokes prepared under identical carbonizing conditions it was shown that rates of reaction with carbon dioxide/nitrogen mixtures at about 1000°C were generally higher for the cokes prepared from coals of above 30% volatile matter. The reaction rates of cokes prepared from certain Durham coals were generally higher than anticipated. Gasification of cokes prepared from certain Durham coals were generally higher than anticipated. Gasification of the cokes resulted in loss of strength, decrease in apparent density, enlargement of pores and reduction of pore-wall thickness. It appeared that burn-off was primarily associated mineral constituents of the coke ash upon gasification rates was detected. A tentative relation was derived between gasification rates and the ratio of pore-wall thickness to pore diameter of the cokes. In turn, this latter ratio appeared to bear some relation to the oxygen content of the coal. The majority of the parameters studied were measured by established techniques. Porosity was determined by mercury pressure porosimetry and the Quantimet 720 automatic image analysis microscope was employed for structural studies. The accuracy of the measurement of pore and pore-wall dimensions was approximately ± 2%.     

Myochrysine solution structure and reactivity

We have determined the framework structure of Myochrysine (disodium gold(I)thiomalate) in the solid state and extremely concentrated aqueous solution, previously. It consists of an open chain polymer with linear gold coordination to two thiolates from the thiomalic acid moieties which bridge between pairs of gold atoms providing an Au-S-Au angle of 95 degrees . The question remained: was this structure relevant to the dilute solutions of drugs administered and the still lower concentrations of gold found in the bodies of patients (typically 1 ppm Au in blood and urine or 5 muM in Au). We have provided an answer to that question using extended X-ray absorption spectroscopy (EXAFS) and capillary zone electrophoresis (CZE). EXAFS studies confirm that the polymeric structure with two sulfur atoms per gold atom persists from molar concentrations down to millimolar concentrations. CZE is able to separate and detect Myochrysine at millimolar levels. More importantly, at micromolar levels Myochrysine solutions exhibit identical CZE behavior to that measured at millimolar levels. Thus, aqueous solutions of the drug remain oligomeric at concentrations commensurate with those found in patient blood and urine.The reactivity of Myochrysine with cyanide, a species especially prevalent in smoking patients, was explored using CZE. Cyanide freely replaces thiomalic acid to form [Au(CN)(2)](-) and thiomalic acid via a mixed ligand intermediate. The overall apparent equilibrium constant (K(app)) for the reaction is 6x10(-4)M(-1). Further reaction of [Au(CN)(2)](-) with a large excess of L, where L is cysteine, N-acetylcysteine, or glutathione, shows that these amino acids readily replace cyanide to form [AuL(2)](-). These species are thus potential metabolites and could possibly be active forms of gold in vivo. That all of these species are readily separated and quantified using CZE demonstrates that capillary electrophoresis is an accessible and powerful tool to add to those used for the study of gold-based antiarthritis drugs.     

Pozzolanic reactivity of lightweight aggregates

Over recent years more attention has been given to the influence of the aggregate-cement paste interfacial zone on the various properties of concrete. For the lightweight aggregate - cement paste interface, it is believed that the interface is characterized by a mechanical interlocking in combination with a chemical interaction in the form of pozzolanic reaction. In the literature, however, not too much information on the effect of the pozzolanic reactivity of lightweight aggregates is available. Therefore, an investigation on the pozzolanic reactivity of some lightweight aggregates based on expanded clay and sintered fly ash was carried out. A certain degree of pozzolanic reaction between cement paste and lightweight aggregate was observed, but the effect was not very pronounced. The low degree of pozzolanic reactivity may be the result of a recrystallization of the mineral compounds during the manufacturing process of the aggregate.     

Group chemical composition of coal batch and reactivity of coke 1. Determining coke reactivity

With a view to finding correlations between coke reactivity and the coal batch employed, methods of determining coke reactivity are considered—in particular, the standard and pulsed methods. The kinetic equation fundamental to all methods of assessing the coke reactivity from the gasification rate constant is presented. The possibility of combining data obtained by different methods of estimating the coke reactivity is established.     

Surface reactivity of MgO oxygen vacancies

The interaction of gas-phase molecules (O₂, CO and H₂) with oxygen vacancies (F_s centers) on the MgO(1 0 0) surface was studied by cluster models ab initio wave functions. The F_s centers exhibit a high reactivity towards O₂, CO and H₂ at variance with the regular sites of the MgO surface. The reaction proceeds through the formation of radical anions, O⁻₂ and CO⁻, via the transfer of one electron trapped in the surface cavity to the empty levels of the adsorbed molecule, and can lead to the heterolytic dissociation of the H₂ molecule.     

Mechanochemical intercalation of low reactivity kaolinite

Complete urea-intercalation of a low reactivity kaolinite from Birdwood has been carried out by co-grinding with urea in the absence of water (mechanochemical intercalation). The effectiveness of mechanochemical intercalation was compared to solution intercalation by X-ray diffraction (XRD), thermal analysis (TG, DTG), diffuse reflectance Fourier transform infrared (DRIFT) spectroscopy and scanning electron microscopy (SEM). In aqueous solution of urea the Birdwood kaolinite was intercalated with difficulty and only 12% intercalation was achieved. After 2 h of co-grinding with solid urea, complete (100%) intercalation was attained. The possible explanation of complete intercalation is that co-grinding of Birdwood kaolin with solid urea can remove the high-defect kaolinite coating, which prevents the intercalation of the low-defect kaolinite particles. The mechanochemical treatment increased the degree of intercalation and in parallel reduced the amount of the crystalline kaolinite phase.