OUTLINE OF REFRACTORY REQUIREMENTS FOR THE IRON AND STEEL INDUSTRY1

One of the greatest obstacles to the development of better refractories for the iron and steel industry has been the failure of the iron and steel men to give refractory manufacturers accurate detailed analysis of chemical, physical and thermal conditions to which the refractories are to be subjected. This paper summarizes briefly some of the conditions to be encountered in the major processes. Blast furnace refractories may be divided according to requirements as follows: Hearth and Bosh brick should withstand the scouring action of molten iron and acid slag at temperatures around 1800°C. Inwall brick should be impervious to hot, reducing gases, should resist the sand blast action of the from particles of ore carried by the gas, should have a low coefficient of thermal expansion and should possess sufficient compressive strength to support the weight of the upper part of the furnace. Top brick should be as dense and resistant to abrasion as possible. Downcomer, Dustcatcher and Gas Line brick should be dense and resist sand blast action of gas heavily laden by particles of charge. Hot Blast Main and Bustle Pipe brick should be of low heat conductivity. Hot Blast Stove brick should not vitrify at 900°C, should have maximum capacity for absorbing and giving off heat, and be of high compressive strength. The by-product coke oven is becoming a big factor in the refractory fields and has major requirements as follows: Canals and Ovens require brick of high thermal conductivity which will resist sudden changes in temperature and will not be affected by reducing gases at high temperatures. Checker brick should have great capacity for absorbing heat. Bessemer converters require brick resistant to slag at temperatures from 1600° to 1700°C, the nature of the slag being determined by whether the process is acid or basic. Requirements for open hearth furnaces are as follows: Roof brick (both acid and basic furnaces) must not only be capable of maintaining an arch but should withstand as much as possible the action of iron oxides at temperatures of 1800°C. Checker brick (both acid and basic furnaces) should possess a maximum capacity for absorbing and giving off heat, and a minimum chemical affinity for oxides from charge. Ports (both acid and basic) must withstand the action of slag splashes, also direct action of flame. The hearth of the furnace consists of several courses of brick (acid or basic depending on the process) upon which is built the hearth proper by means of many layers of crushed refractory of the same nature. This crushed material must frit together at high temperatures without excessive softening.     

Increasing the lining life of arc furnaces for melting of cobalt

Conclusions Experimental refractory parts and a ramming mixture produced from baddeleyite concentrate have been successfully tested under conditions of the pyrometallurgical processes for production of cobalt.The chemical composition and microstructure of magnesite and baddeleyite refractories after service in production furnaces for melting of cobalt were investigated.It is desirable to line these furnaces differentially. The point of maximum wear, the charging hole, is lined with castable refractories, the side walls in the zone of entry of the electrodes with granular baddeleyite mixture-base sintered refractories, and the zone of the journals with monolithic shaped inserts produced from baddeleyite ramming mixture. The remaining portion of the lining must be made of increased density magnesite brick. Such a lining method makes it possible to substantially lengthen the furnace campaign and reduce repair costs, which in general leads to an increase in their productivity.Translated from Ogneupory, No. 2, pp. 48–51, February, 1989.     

Service of mullite-corundum refractories in the center portion of the roof of high-power electric arc furnaces

Conclusions Type MKS domestic mullite-corundum parts to Technical Standard 14-8-140-75 have been introduced for the center portion of the water cooled roof of high-power arc steel melting furnaces at Belorussian Metallurgical Plant. The length of the roof campaign reached 180–220 heats without intermediate repairs, which is 25% longer than the life of imported refractories.The design of the center portion of the roof without a hole for charging of loose materials provides with the forms and dimensions of the parts used a symmetric lining and uniform distribution in it of the thermomechanical loads, which provides uniform wear of the lining and eliminates deformation of it during service of furnaces.On the basis of investigation of samples of the imported and domestic mullite-corundum roof parts after service it was established that wear of the lining occurs by fusion as the result of interaction of the refractories with the melting dust at 1660–1710°C.Different relative rates of chemical transformation and fusion of the mineral phases of the refractories were revealed. Mullite interacts with the melting reactants and fuses most intensely. In connection with this its content in mullite-corundum roof parts must not exceed 15–20%.Translated from Ogneupory, No. 1, pp. 56–60, January, 1987.     

The wear of magnesia refractories in electric furnaces for melting cast iron

Conclusions The wear of magnesia refractories, i. e., magnesite, perictase — spinel, and magnesite — chromite bricks and magnesite — phosphate mortar, in the walls of electric furnaces for melting cast iron is the result of the solution predominantly of the periclase crystals and to a lesser extent of the spinel in the lowbasicity ferrosilicate slag melt. Brick of the PShS type proved to be the most durable refractory. The use of high-alumina brick in the roof of the furnaces accelerates the wear of the magnesia bricks in the walls.To increase the durability of the lining of these furnaces trials should be carried out with an all-basic wall lining constructed of high-density PShSP-type brick on MF-1-type magnesite — phosphate mortar and a roof lining constructed of MKhS brick and the same mortar.Translated from Ogneupory, No. 4, pp. 44–49, April, 1976.     

Untersuchungen zum Schmelzverhalten von verstrecktem Polyäthylen

The melting behaviour of drawn crystalline polymers is strongly influenced by the shrinkage which takes place simultaneously. This is shown by measurements with a differential colorimeter for 1200% drawn linear polyethylene. A higher melting point, a broader melting range and a slightly higher heat of fusion are observed, if the shrinkage is prevented during the melting experiment. Additionally, the observed melting point is falsified by superheating, if heating rates ≥ 0,5°C/min are used. This has been shown by annealing and irradiation experiments. The elimination of these two effects — shrinkage and superheating — which have been neglected in all earlier investigations, results in a melting peak temperature of 134,8°C and an upper limit of the melting range 137,2°C. Further, attention is drawn to the morphological changes and the related increase of the long period, which take place during heating the drawn material even if the shrinkage is prevented. The effect of these changes of structure upon the melting behaviour is not yet known.     

Solar experimental methods for observing melting plateaux and associated temperature measurements for refractory oxides from 2000 to 3000 °C

Melting points of refractory oxides at high temperature can be obtained through different techniques (resistive furnaces, induction furnaces, laser beams, imaging furnaces …). Here, we present a solar furnace experimental setup and methods developed at the Odeillo Solar Furnace (IMP-CNRS) and used to measure melting and freezing plateau temperatures between 2000 and 3000 °C.We detail a new procedure we have developed that produces a controllable, long duration temperature plateau, and we discuss the appropriate temperature measurement method.The principle is to heat a self-crucible product with the solar concentrated flux and to preserve the thermal equilibrium at the melting point temperature by providing a continuously regulated solar flux supply. Two critical points are treated: the control of the right level of temperature and its measurement, which is hampered by the solar reflection.Results obtained with Al₂O₃ (melting point = 2053 °C) are presented as example.     

EFFECT OF MOLTEN ALUMINUM ON VARIOUS REFRACTORY BRICK*

To study the effect of molten aluminum on refractory brick with a view toward explaining some of the brick failures in aluminum melting furnaces, the following test was conducted. Brick of different compositions and from various manufacturers were placed on end in the bottom of an electrically heated ladle to which molten aluminum was added. After holding the molten aluminum in contact with the brick for thirty-five days, it was poured out and the ladle was allowed to cool slowly to room temperature. A study of the brick revealed that some failed by penetration of the aluminum into the brick accompanied by a reaction between the aluminum and the brick. This penetration was less with the denser brick than with the more porous ones. Of the brick tested, there was the least reaction between aluminum and the chrome brick and most between aluminum and silica brick. Many other factors, however, must be considered when deciding which brick is the most economical to use in aluminum melting.     

THE PREVENTION OF DISINTEGRATION OF BLAST FURNACE LININGS1

Theories and observations on the causes of disintegration of fireclay refractories in blast furnaces are given and a process is developed for improving high iron clays for this use. The disintegration of refractories in blast furnace linings is initiated by alteration in the iron spots. Ferric oxide is reduced to ferrous oxide at 500°C and hastens the cracking of 2CO to CO₂+C₁ the carbon being retained by the lining. When Fe₂O₂ is converted to Fe₃O₄ the brick will not disintegrate.     

不锈钢冶炼用铁水包Al2O3-SiC-C内衬砖的性能与侵蚀机理

铁水包内衬材料长期服役于间隔周期较长的高、低温交替环境,极易发生剥落与侵蚀损毁。为了探索影响铁水包内衬材料使用寿命的主要因素,对市面上四种铁水包Al₂O₃-SiC-C内衬砖的化学成分、物相组成、物理性能和微观结构进行了分析,并以高炉渣为侵蚀介质,重点研究了不锈钢冶炼用铁水包Al₂O₃-SiC-C内衬砖的侵蚀机理。结果表明:铁水包Al₂O₃-SiC-C内衬砖中Al₂O₃含量越高,高温下制品的液相量越低,越有利于提高耐火砖的高温力学性能;随着含碳量的增加,铁水包Al₂O₃-SiC-C内衬砖的抗渣性得到明显改善,但抗氧化性及高温抗折强度呈下降趋势;高炉渣中CaO、MgO向耐火砖中渗透,与耐火砖中的Al₂O₃、SiO₂发生反应形成高熔点的镁铝尖晶石及低熔点的钙长石等,生成的低熔相会加剧耐火砖的侵蚀。     

Experience in manufacturing tar-dolomite brick and testing it in service

Conclusions The results of petrographic and chemical analysis show that tar-dolomite brick can be used satisfactorily for the lining of electric steel-smelting furnaces.It is advisable to test the dolomite brick made by the above-described production process in the lining of converters using oxygen.     

Life of refractories made of Tal'skiy magnesite

Conclusions Magnesite brick made of Tal'skiy magnesite serves somewhat better than standard magnesite brick and can be used for lining open-hearth furnaces.Magnesite brick with the addition of scale and chrome-magnesite brick made from Tal'skiy magnesite serve just as well as the corresponding refractories from the Satka material, and can be used to line the walls of open-hearth furnaces.Magnesite-chrome brick made with Tal'skiy magnesite serves just as well as standard magnesite-chrome brick and can be used to line the roofs of open-hearth furnaces.Metallurgical powder made from Tal'skiy magnesite serves just as well as Satka magnesite powder and can be used both as a weld-on and as a servicing material for open-hearth furnace hearths.Tal'skiy magnesite of the experimental type is an industrial raw material for making high-grade magnesian refractories.     

高炉炉身采用高导热高强度石墨砖技术

为了提高高炉的使用寿命和产能，宝钢4号高炉的炉身采用了密集式冷却板加高导热、高强度石墨砖的内衬结构。为减缓炉衬使用过程中受热应力的影响，在研究石墨砖及配套胶泥的技术指标到具体的结构设计等过程中，都采取了特殊方法。     

Surface Melting in Alkane Emulsion Droplets as Affected by Surfactant Type

The influence of surfactant type (Tween 20, Tween 40, Tween 60, Tween 80, Brij 58, Triton X-100, SDS, STS) on the crystallization and melting characteristics of emulsified (mean droplet diameter 0.52 μm) n-octadecane and n-eicosane were studied using microcalorimetry. The melting point (~37 °C) of the eicosane droplets was higher than the crystallization point (~24 °C) and was not affected by the surfactant selected. There was a similar separation between the crystallization (~14 °C) and melting (~28 °C) point of the emulsified octadecane however the details of the transitions was affected by the surfactant selected. For Tween 40 and Brij 58-stabilized droplets there was a split peak on crystallization which we attribute to a surface heterogeneous nucleation mechanism. Only these surfactant-alkane combinations had a split peak on melting. The size of the lower temperature fraction decreased with droplet size suggesting another surface effect. However, the size of the surface layer was calculated to be many times the length of the surfactant tail suggesting the crystal structure was modified by the nucleation mechanism.     

澳斯麦特铜熔炼炉渣线用后铝铬残砖的分析

对澳斯麦特铜熔炼炉渣线部位使用后的铝铬砖进行了XRD、SEM和EDS分析。结果表明:在使用过程中,铝铬砖中的Al2O3、Cr2O3与渗入熔渣中的FeO反应生成高熔点的铁铝尖晶石和铁铬尖晶石,从而阻止炉渣对耐火材料的进一步侵蚀,延长炉衬的使用寿命;炉渣中的SiO2和CaO主要与砖中的Al2O3反应生成低熔点的硅酸盐相Ca(Al2Si2O8)。     

A high-alumina lining for crucible-type induction furnaces

Conclusions In crucible-type induction furnaces, the durability of a lining of compound MLM-1 (Technical Specifications 14-8-119-74) is several times higher than that of a quartzite lining or a sintered lining based on corundum and kyanite-sillimanite concentrate. The compound can be recommended for crucible furnaces when melting high-grade cast iron and steel.The density of compound MKE-78 can be increased by adding up to 20% synthetic corundum No. 6 and 3–4% orthophosphoric acid solution. Its high refractoriness makes it possible to use this lining as well for melting steel with a casting temperature of 1680–1700°C Its durability in this case is at least 2 months.Translated from Ogneupory, No. 3, pp. 24–28, March, 1977.     

Practice of application of refractory concrete in industrial furnaces

The Teploograzhdenie Research-and-Production Company has developed refractory concretes with service temperature of 1150–1650°C which have been successfully used as car bottom lining in tunnel furnaces, block lining of the hearth and lower parts of thermal furnace walls (together with the Termostal’ JSC), lining of roof panels of a continuous furnace, and burner stones. __________ Translated from Novye Ogneupory, No. 11, pp. 18–19, November, 2006.     

X-ray imaging of a high-temperature furnace applied to glass melting

The dynamics of soda-lime-silica glass grain melting is investigated experimentally using a nonintrusive technique. A cylindrical alumina crucible is filled with glass cullet and placed into a furnace illuminated by an X-ray source. This glass granular bed is gradually heated up to 1100°C, leading to its melting and the generation of a size-distributed population of bubbles rising in the molten glass. An image processing algorithm of X-ray images of the cullet bed during melting allows the characterization of bubbles size distribution in the crucible as well as their velocity. The introduction of tin dioxide μ-particles in the glass matrix before melting enhances the texture of the images and makes possible the determination of the bubble-induced molten glass velocity field by an optical flow technique. The bubble size distribution can be fitted by a log-normal law, suggesting that it is closely related to the initial size distribution in the cullet bed. The liquid motion induced by the bubbles in Stokes' regime is strongly affected by the flow confinement and the determination of bubble rising velocity along its trajectory unveils the existence of local tiny temperature fluctuations in the crucible. Overall, the measuring techniques developed in this work seem to be very promising for the improvement of models and optimization of industrial glass furnaces.     

加废钢条件下铁水包的异常侵蚀与用材问题探讨

对铁水包的异常侵蚀进行了调研,对铁水包用砖的性能、组成与结构进行分析.结果表明:1)铁水包包壁采用的铝碳化硅碳砖与包底用铝碳化硅碳砖不同,含较多的叶蜡石,Al2O3含量只有36.32％(w);体积密度、显气孔率、耐压强度均低于行业标准的要求;其抗氧化性差,使用过程中氧化形成多孔层,造成砖衬结构疏松,引起断砖、局部磨损及...     

Service of zirconia refractories in continuous furnaces for quartz glass melting

Data are given on the durability of baddeleyite refractories of grade TsTsPP, which contain no stabilizing additives, in operation in the lining of continuous furnaces for melting quartz glass at the Dzerzhinskii Glass Works. In operation in contact with molten quartz at a temperature of (2000 Mp 10)°C, the average (for a year) durability has increased up to 82.5 days compared with the lining made of refractory sectors of CaO-stabilized ZrO₂, which had a durability in these furnaces up to 25 days. It is noted that the durability of furnace linings made of baddeleyite refractories is limited by the durability of the roof plates. With the use of a water-cooled roof, the durability of the furnace lining was increased up to 267 days, but the heat losses were higher. The results of comparative tests of baddeleyite refractories with different porosity (between 9.6% and 22.3%) and of those based on natural baddeleyite of natural grain size and on electrofused ZrO₂ are given. No differences in their durability have been established. The results of examining the refractories after their operation in furnaces are also considered.Translated from Ogneupory, No. 2, pp. 25 – 28, February, 1994.     

Synthesis of Alkali Aluminosilicates — Materials for Alkali Contaminated Environments at High Temperatures

Alkali corrosion has become a problem in industrial furnaces especially because of the increasing use of secondary fuels. In the corroded lining material alkali aluminosilicates such as kalsilite, leucite or nepheline could be identified. According to ternary phase diagrams these substances have very high melting points which would make them suitable for high temperature applications in alkali corrosive environments. This study presents systematic synthesis experiments to produce alkali aluminosilicates by thermal (800°C, 1000°C, 1200°C) and hydrothermal (200°C) treatment starting from the nominal compositions of KAlSi₂O₆, KAlSiO₄, and NaAlSiO₄., KOH NaOH, quartz powder, and Al(OH)₃ were used as raw materials. The phase composition was analyzed by using X‐ray diffraction (XRD). The alkali corrosion was tested using alkali salts as corrosive substances. The synthesis experiments resulted in multiphase reaction products. The hydrothermal method yielded only for the initial composition according to the stoichiometry of KAlSiO₄ crystalline phases of the same composition. The thermal method produced for all sets of synthesizing parameters mixtures of stoichiometric and nonstoichiometric alkali aluminosilicates. In the corrosion test, material of the nominal composition of KAlSiO₄ showed the best results. The material was corrosion resistant independently from the initially applied synthesizing parameters.