Analysis of All-Carbon Brick Bottom and Ceramic Cup Synthetic Hearth Bottom

One of the bottlenecks of the blast furnace （BF） campaign is the life length of hearth bottom. The basic reason for the erosion of hearth bottom is its direct contact with hot metal. According to the theory of heat transfer, models of BF hearth bottom are built based on the actual examples using software and VC language, and the calculated results are in good agreement with the data of BF dissection after blowing out. The temperature distribution and the capability of the resistance to erosion for different structures of hearth bottom are analyzed, especially the two prevalent kinds of hearth bottom arrangements called ＂the method of heat transfer＂ for all-carbon brick bottom and ＂the method of heat isolation＂ for ceramic synthetic hearth bottom. Features of the two kinds of hearth bottoms are analyzed. Also the different ways of protecting the hearth bottom are clarified, according to some actual examples. After that, the same essence of prolonging life, and the fact that the existence of a ＂protective skull＂ with low thermal conductivity between the hot metal and brick layers is of utmost importance are shown.

Optimization for the structure of BF hearth bottom and the arrangement of thermal couples

The hearth of “heat transfer method” and the ceramic cup synthetic hearth bottom of “heart isolation method” are two most popular designs for blast furnace (BF). Although there are successful real examples, some disadvantages, for instance large heat loss and high cost, still exist for these designs. According to the theory of heat transfer, based on the calculation of temperature distribution of the hearth bottom, it is elucidated that all brick layers at the hearth bottom may not be considered as the only reason why different structures exhibited different temperature distributions although total heat resistance is the same, and then based on the effect of hot metal and cold water on different temperature distribution ranges, the concepts of “heat resistance” and “cooling enhancement” are put forth. Based on this, the disadvantages and the factors affecting temperature distribution, of the two types of hearth bottoms were illustrated. On the basis of these analyses, a novel structure for BF hearth bottom designing that can easily form “self-protecting” slag layer stably, called “the method of gradient brick layout that has an optimum combination of cooling enhancement and heat resistance” was proposed; it can not only prolong the hearth bottom longevity but also reduce the cost and heat loss. Also, the optimum arrangement of thermal couples in hearth bottom was suggested based on the previous studies on erosion prediction carried out by the author.

Numerical simulation for the lower shaft and the hearth bottom of blast furnace

One of the methods forming the shell is to appropriately design the coolingstaves and hearth without overheating during the campaign life of the furnace. The three-dimensionalsteady mathematical models for calculating the temperature distribution in the coolers andtwo-dimensional unsteady mathematical models with phase-change latent heat for calculating thetemperature distribution of the hearth bottom were established. The calculation results show thatthe formation of the slag-metal protection shell can be achieved by optimizing the design parametersof the coolers. Increasing the heat conductivity of the carbon brick can move the isothermal lineof 1150 deg C upward outside the hearth bottom.

Optimization for the structure of BF hearth bottom and the arrangement of thermal couples

The hearth of ＂heat transfer method＂ and the ceramic cup synthetic hearth bottom of ＂heart isolation method＂ are two most popular designs for blast furnace （BF）. Although there are successful real examples, some disadvantages, for instance large heat loss and high cost, still exist for these designs. According to the theory of heat transfer, based on the calculation of temperature distribution of the hearth bottom, it is elucidated that all brick layers at the hearth bottom may not be considered as the only reason why different structures exhibited different temperature distributions although total heat resistance is the same, and then based on the effect of hot metal and cold water on different temperature distribution ranges, the concepts of ＂heat resistance＂ and ＂cooling enhancement＂ are put forth. Based on this, the disadvantages and the factors affecting temperature distribution, of the two types of hearth bottoms were illustrated. On the basis of these analyses, a novel structure for BF hearth bottom designing that can easily form ＂self-protecting＂ slag layer stably, called ＂the method of gradient brick layout that has an optimum combination of cooling enhancement and heat resistance＂ was proposed; it can not only prolong the hearth bottom longevity but also reduce the cost and heat loss. Also, the optimum arrangement of thermal couples in hearth bottom was suggested based on the previous studies on erosion prediction carried out by the author.

Mathematical Model of Hearth and Bottom Erosion in Blast Furnace

Furnace lining erosion is closely related to the operation stability and safety. The detection technology for hearth lining thickness of blast furnace was introduced.By using the data of thermocouples installed in the bottom of furnace hearth,a mathematical model of erosion was established; the real state of the hearth and bottom erosion was studied; the erosion condition was followed,serving for the furnace longevity.

Formation mechanism of the protective layer in a blast furnace hearth

A variety of techniques, such as chemical analysis, scanning electron microscopy-energy dispersive spectroscopy, and X-ray diffraction, were applied to characterize the adhesion protective layer formed below the blast furnace taphole level when a certain amount of titanium-bearing burden was used. Samples of the protective layer were extracted to identify the chemical composition, phase assemblage, andistribution. Furthermore, the formation mechanism of the protective layer was determined after clarifying the source of each componenFinally, a technical strategy was proposed for achieving a stable protective layer in the hearth. The results show that the protective layemainly exists in a bilayer form in the sidewall, namely, a titanium-bearing layer and a graphite layer. Both the layers contain the slag phaswhose major crystalline phase is magnesium melilite（Ca2Mg Si2O7） and the main source of the slag phase is coke ash. It is clearly determinethat solid particles such as graphite, Ti（C,N） and Mg Al2O4play an important role in the formation of the protective layer, and the key factofor promoting the formation of a stable protective layer is reasonable control of the evolution behavior of coke.

Numerical simulation of the direct reduction of pellets in a rotary hearth furnace for zinc-containing metallurgical dust treatment

A mathematical model was established to describe the direct reduction of pellets in a rotary hearth furnace （RHF）. In the model, heat transfer, mass transfer, and gas-solid chemical reactions were taken into account. The behaviors of iron metallization and dezincification were analyzed by the numerical method, which was validated by experimental data of the direct reduction of pellets in a Si-Mo furnace. The simulation results show that if the production targets of iron metallization and dezincification are up to 80% and 90%, respectively, the furnace temperature for high-temperature sections must be set higher than 1300~ C. Moreover, an undersupply of secondary air by 20% will lead to a decline in iron metallization rate of discharged pellets by 10% and a decrease in dezincing rate by 13%. In addition, if the residence time of pellets in the furnace is over 20 min, its further extension will hardly lead to an obvious increase in production indexes under the same furnace temperature curve.

Study on the early warning mechanism for the security of blast furnace hearths

The campaign life of blast furnace （BF） hearths has become the limiting factor for safety and high efficiency production of modern BFs. However, the early warning mechanism of hearth security has not been clear. In this article, based on heat transfer calculations, heat flux and erosion monitoring, the features of heat flux and erosion were analyzed and compared among different types of hearths. The primary detecting elements, mathematical models, evaluating standards, and warning methods were discussed. A novel early warning mechanism with the three-level quantificational standards was proposed for BF hearth security.

Formation mechanism of the graphite-rich protective layer in blast furnace hearths

A long campaign life of blast furnaces is heavily linked to the existence of a protective layer in their hearths. In this work, we conducted dissection studies and investigated damage in blast furnace hearths to estimate the formation mechanism of the protective layer. The results illustrate that a significant amount of graphite phase was trapped within the hearth protective layer. Furthermore, on the basis of the thermodynamic and kinetic calculations of the graphite precipitation process, a precipitation potential index related to the formation of the graphite-rich protective layer was proposed to characterize the formation ability of this layer. We determined that, under normal operating conditions, the precipitation of graphite phase ~om hot metal was thermodynamically possible. Among elements that exist in hot metal, C, Si, and P favor graphite precipitation, whereas Mn and Cr inhibit this process. Moreover, at the same hot-face temperature, an increase of carbon concentration in hot metal can shorten the precipitation time. Finally, the results suggest that measures such as reducing the hot-face tem- perature and increasing the degree of carbon saturation in hot metal are critically important to improve the precipitation potential index.

Numerical Simulation of Fluid Flow in Blast Furnace Hearth

The liquid flow in blast furnace hearth can result in the erosion of hearth. To prolong the campaign life of blast furnace, the effects of coke bed structure, coke porosity and deepness of taphole on liquid flow in hearth were studied by re model under different conditions. The results show that with the decrease of coke porosity, the peripheral flow is enhanced. Moreover, the existence of narrow coke free zone and the deepness reduction of taphole can increase the flowability on the bottom of hearth.

Investigation on the relationship between hearth wall erosion and deadman permeability for large blast furnaces

In this study, the relationship between hearth wall erosion and deadman permeability was investigated based on the change in the hearth bottom and hearth sidewall temperatures. Additionally, the operation practice for controlling hearth wall erosion in the large No. 1 blast furnace at Baosteel was also investigated. The reasons for the decrease in the permeability of deadman coke were analyzed, and measures for improving the permeability of deadman coke and controlling hearth wall temperature rising were described. The results show that a decrease in deadman coke permeability is the main reason for refractory temperature increase and hearth wall erosion. This indicates the importance of monitoring changes in hearth working conditions and taking appropriate measures to maintain sufficient permeability of the deadman and balance the hot metal flow and drainage of slag. At this rate, the decline in the hearth bottom temperature and fast rising of the hearth wall temperature can be restrained.

Preparation of ZnO Nanoparticles from Zn-containing Rotary Hearth Furnace Dust

To solve the problem of the low added value Zn-containing rotary hearth furnace(RHF)dust,two deep eutectic solvents(DESs)were employed,such as choline chloride-urea(ChCl-urea)and choline chloride-oxalic acid dihydrate(CC-OA)solvent and Zn-containing RHF dust(water-washed)as the research target.Then,we prepared ZnO nanoparticles using two DESs or their combination,namely,ChCl-urea(Method A),CC-OA(Method B),first CC-OA and then ChCl-urea(Method B-A)and first ChCl-urea and then CCOA(Method A-B),respectively.The effects of these methods on the properties of as-obtained precursors and ZnO nanoparticles were investigated in detail.The results indicated that the precursor obtained by Method A was Zn_(4)CO_(3)(OH)_(6)·H_(2)O,and those by Methods B,B-A,and A-B were all ZnC_(2)O_(4)·2H_(2)O.Moreover,the decomposition steps of the last three methods were similar.The ZnO contents of 95.486%,99.768%,99.733%,and 99.76%were obtained by Methods A,B,B-A,and A-B,respectively.Methods A,B,and B-A led to the formation of spherical and agglomerated ZnO nanoparticles with normal size distributions,where Method B showed the best distribution with an average diameter 25 nm.The ZnO nanoparticles obtained by the Method A-B did not possess good properties.

Erosion Mechanism of Al_(2)O_(3)-SiC Castables for Lining Maintenance in Blast Furnace Hearths

Al_(2)O_(3)-SiC castables,for the relining of BF hearths in mid-campaign repair,were sampled and investigated after two years’service.The chemical and mineralogical characteristics of the residual castables were analyzed by X-ray diffraction,scanning electron microscopy,and energy dispersive X-ray spectrometry to study the erosion mechanism.The results show that as gaseous K diffuses in the castables,leucite(KAlSi_(2)O_(8))and multiple cracks are formed.Molten iron and slag penetrate through the cracks to form anorthite([Ca,Na][Al,Si]_(4)O_(8))and iron,which will not form an embrittlement layer similar to carbon bricks.The entire repair of the hearth with Al_(2)O_(3)-SiC castables combined with the design of thin-wall lining hearth eliminates“elephant foot shaped”erosion,greatly prolonging the service life of the hearth lining.

Longlife technologies of hearth area for blast furnace at Bengang

The problem of shortlife hearth of blast furnace was solved through the adoption of longlife technologies such as the application of UCAR hot pressed carbon brick-ceramic cup compound lining technology, closed-loop soft water cooling system,enhancing taphole maintenance and schreyerite lining protection etc. Longlife and high productivity had been achieved successfully.The transition of technological processes of the hearth for blast furnaces at BenGang are outlined in this paper.

Development and Introduction of Monitoring System of Refractory Lining Wear in Blast Furnace Hearth

To diagnose the lining condition of the blast furnace hearth during its campaign, are widely used methods based on the analysis of the temperature characteristics of the refractory lining. Measurement of the temperature characteristics is performed by means of a few hundred thermocouples placed inside the refractory lining. The peculiarity of proposed and used mathematical models is a fully three-dimensional assessment of the refractory lining, presence mechanisms of adaptation to the actual thermal conductivity of refractories and optimization calculations to the work in the on-line mode. The new monitoring systems of the lining wear of the blast furnace hearth are established on 5 blast furnaces of integrated iron-and-steel works of China： No.4 by volume 3,200 m3 of “Jinan Iron ＆ Steel Company” in Jinan （683 thermocouples）, No.2 by volume 1,080 m3 of “Henan Jiyuan Iron ＆ Steel （Group） Company” in Jiyuan （212 thermocouples）, No.4 by volume 2,500 m3 of “Guangxi Liuzhou Iron ＆ Steel （Group） Company” in Liuzhou （383 thermocouples）, No.3 by volume 1,750 m3 of “Jinan Iron ＆ Steel Company” in Jinan （524 thermocouples）; No.1 by volume 1,750 m3 of “Jinan Iron ＆ Steel Company” in Jinan （524 thermocouples）.

Cooling Water Flow Rate Calculation for Hearth of Large Blast Furnaces

The cooling water flow rate for hearth of large blast furnaces was calculated by simulation. The results show that the cooling water flow rate shall be above 4 200m3/ h for hearth of large blast furnaces; to meet requirements of the increasing smelting intensity and to ensure the safety at the end of the first campaign,the designed maximum cooling water flow rate should be 5 900m3/ h; according to the flow distribution stability and the calculated resistance loss,hearth cooling stave pipes with the specification of 76 mm × 6 mm shall be adopted to assure the flow velocity in pipes of hearth cooling stave in the range of 1. 9- 2. 3 m / s.

Hearth and Home＂ A Psycho-Sexual Reading of Procreating the Vampire Race in Dracula by Bram Stoker

It is in the spirit of a ＂new family unit＂ that Dracula attempts vampire procreation in Bram Stoker＇s Dracula （2000） The themes of proper lineage and procreation juxtaposed with archaic late Victorian ideas invite exploration in this timeless novel. The novel is considered Gothic, yet it meets the cultural milieu of the fin de sikcle contemporary London of the 1890s. As the novel is considered fairly contemporary for its time, it is important to note that given new scientific theories such as eugenics, it is possible that Stoker was attempting to show a new kind of family unit---one that is not begot of the actual sex-act, but rather one that is propagated through the mingling of blood as a replacement for semen. There is much evidence in the novel to suggest that he not only wants to continue his family, but also that he is a true Renaissance ＂man＂ in his knowledge of other cultures, his pleasure and decadence in the finer material possessions, and his consumption of private property to continue his lineage in comfort and safety. It is clear in the novel that a brief analysis of the concepts of progeny and eugenics that the character of Dracula can be read as a ＂regular guy＂ simply trying to continue his lineage in an unforgiving and judgmental world. Dracula is violent in his preservation of his lineage, but he only does so to ensure he will not have to be a night-dweller on his own for eternity. He is a kind of demonic cupid with piercing fangs instead of angelic arrows He has to kill the human soul to obtain this obsessive dream of hearth and home

长钢8号高炉炉缸炉底破损调查及长寿经验

对长钢8号高炉炉缸炉底破损调查及长寿经验进行了总结分析。8号高炉一代炉役寿命9年10个月,单位炉容产铁量10640t/m^(3),停炉后进行的炉缸炉底破损调查结果表明,炉缸与炉底交界处侵蚀最为严重,呈象脚状侵蚀,炉缸炭砖部分环裂,炉底5层满铺炭砖完好,炉缸侵蚀的原因主要是铁水环流、铁水溶蚀、有害元素侵蚀和热应力等。8号高炉这一代炉役的长寿经验:一是均衡稳定的生产组织;二是长期稳定顺行的炉况;三是及时采取相应的护炉生产措施,四是合理应用炉体维护技术。

钼精矿多膛炉氧化焙烧炉床底料增厚机理分析

工业上一般采用氧化焙烧-氨浸工艺处理钼精矿,多膛炉在氧化焙烧钼精矿过程中时常出现烧结现象,造成炉床增厚,严重影响生产。针对此问题,本文以某公司钼精矿多膛炉炉床底部增厚料为研究对象,进行垂直立体取样检测,分析样品的物相组成与微观形貌,结果表明,炉底增厚料底层由CaMoO_(4)、CuMoO_(4)、CuSO_(4)、CaSO_(4)等杂质,以及MoO_(3)和MoO_(2)物相组成;中层主要由MoO_(3)以及少量Mo_(4)O_(11)、MoO_(2)和CaSO_(4)等物相组成;顶层主要由MoO_(3)以及极少量Mo_(4)O_(11)、MoO_(2)物相组成。分析认为炉底增厚料初期大量杂质元素在铺底料(SiO_(2))表面富集,形成“黏结”的低熔点化合物;随着生产进行,低熔点化合物和钼氧化物在初期增厚料底层上进一步沉积形成炉底增厚料顶层料,随着生产时间的增长,炉底增厚料不断沉积增厚。通过控制入炉原料杂质元素种类及含量、焙烧温度、物料搅拌强度、焙烧时间、料层厚度等措施可以减小炉底料的增厚速度,减少多膛炉炉床维护,节约生产成本。

Experimental study on influence of blade angle and particle size on particle mechanics on a batch-operated single floor of a multiple hearth furnace

In industry,multiple hearth furnaces are used for the thermal treatment of particulate material.The current contribution concentrates on the experimental analysis of particle mechanics for a batch-operated single floor of a multiple hearth furnace.The particles are agitated on the circular floor by a single,rotating rabble arm equipped with three flat rabble blades of 10 mm thickness.The blade angle,defined as the angle,which the blade is inclined against the tangential direction,is varied from 0°to 90°.A single layer of spherical polyoxymethylene(POM)particles with three different diameters(5,10 and 20 mm)is placed on the floor.To analyze the results,two parameters have been extracted from image analysis when the bed of particles is agitated,first,the area not covered by particles and second,the frequency distribution of the mean distance among the particles.The particle free surface area increases with the inclination of the blades.The evolution of the particle free surface area differs for the different particle diameters.In general,the maximum particle free area for all blade angles is the largest for the 5 mm particles followed by the 20 mm particles.For the 10 mm particles,the particle free surface area starts for a blade angle of 0°at larger values than for the 20 mm particles but the values fall below the values for the 20 mm particles for larger blade angles.The reason for this behavior is discussed in detail.The mean distance among the particles is a parameter characterizing the length scales dominating the effects on the floor.The frequency distribution of the mean distance among particles provides infor-mation about the morphology of the particle bulk,for example,whether the free surface area is inter-spersed with particles.