Mechanism of overgrowth of steel-teeming nozzles

Conclusions A mechanism has been proposed for overgrowth of ladle teeming nozzles assuming the formation in deoxidation of steel of crystallization structures of oxide particles in the form of metallized tangles of nonmetallic inclusions with subsequent precipitation of them on the walls of the nozzle channel in teeming.The primary factor influencing freezing of the metal impregnating the skeletons of nonmetallic inclusions is the reduction in temperature of the refractory surface to temperatures less than the melting point of the metal impregnating the skeletal formations of nonmetallic inclusions.The probability of overgrowth drops with a decrease in thickness of the boundary high-velocity layer, which may be obtained by use of slippage of the flow of metal on the boundary with the poorly wetted refractory. The effect of slippage is strengthened by external porosity of the refractory.Failure of the skeletal formations in the boundary layer is promoted by eutectic fusion of the nonmetallic inclusions in contact of them with the wall of the refractory nozzle.Translated from Ogneupory, No. 1, pp. 30–34, January, 1993.     

Refractories for the slide gates of the steel-teeming ladles of the electric melt shop of belorussian metallurgical plant

Conclusions The imported refractories and design of the slide gate were analyzed. Experience in their use, which may be used in domestic practice for increasing refractory life and improving the designs of refractories and gates and the method of teeming steel through slide gates, was obtained.At Belorussian Metallurgical Plant a set of domestic refractories has been introduced in the Interstop slide gate in place of the imported ones. The life of the domestic refractories is equal to or exceeds that of the imported analogs.Translated from Ogneupory, No. 6, pp. 51–55, June, 1989.     

Unfired periclase and periclase-graphite nozzles,collector-nozzles,and inserts for teeming of steel

Conclusions Line production of unfired periclase-graphite nozzles and collector-nozzles with ligno-sulfonate binder, which have obtained wide use in teeming of steel through slide gates, has been developed and introduced.A method for holder-enclosed unfired periclase-graphite collector-nozzles with phosphate binder providing normal teeming of two heats from 100-ton ladles has been developed.The results of service tests of unfired nozzles and inserts with phosphate binder in a number of plants have provided stable stopper teeming of various types of steel and have shown the possibility of replacement of fired parts by them.Replacement of fired nozzles and inserts with unfired ones makes it possible to shorten the production cycle by three times, to save 150 kg of standard fuel per ton of parts, and to eliminate the laborious operations of loading on the kiln cars and scrap for heat cracks, deformation, and out-of-roundness of the circumference of the channel.Optimization of the form and dimensions of the collector-nozzle channel, the cross section of which has the form of a portion of a circle, makes it possible to improve the configuration of the transformer steel stream and its flow and, consequently, to increase quality and the yield of acceptable metal.Translated from Ogneupory, No. 7, pp. 47–50, July, 1987.     

Increasing the number of uses of the refractories in the slide gates of large steel-teeming ladles

Conclusions A method of enrichment of brucite by washing and sorting of it was developed. An experimental lot of composite slide gate plates for two teemings from the 300-ton steel teeming ladles of Magnitogorsk Metallurgical Combine was prepared from enriched fused brucite at Magnesite Combine. The physicochemical indices of the plates were 97.9 wt.% magnesium oxide with a nonequiaxiality of the periclase crystals of 1.94, 0.3% silica, 0.2% iron oxide, compressive strength 110 N/mm², and open porosity 12%. Under conditions of repeated openings and closings the plates made it possible to provide 100% quality teeming of the first heat and to direct 60% of the slide gates to repeated teeming, which was done with 32%. For a final experimental verification it would be desirable to prepare a larger experimental production lot of refractories using the method developed with specific repeated use.Translated from Ogneupory, No. 2, pp. 47–51, February, 1988.     

Life of stopper heads in continuous steel casting

Conclusions Chamotte heads with 5, 10 and 15% graphite differ from conventional chamotte by high thermal endurance, thermal conductivity and wear resistance. The increased rigidity of stopper heads with a graphite content of 5 to 15% used in combination with magnesite sleeves enhances the formation of longitudinal cracks.Chamotte specimens fired at 1230° C are endowed with high wear-resistance. They differ from conventional chamotte refractories by higher thermal endurance and provide for good stopper service in reladling killed steel.High-alumina SP-9-type heads made at Chasov-Yar Combine wear less in intermediate ladles and are endowed with greater thermal strength than chamotte heads.The higher quality of the chamotte heads under conditions of Stalino Metallurgical Plant in comparison to that of Krasnoye Sormovo Plant is not only due to the quality of the refractory but also to such factors as the rate and degree of preheating intermediate ladles before filling with metal, careful placement of the stoppers, and use of graphite packing around the teeming head.Despite higher wear SP-12-type chamotte heads made at Chasov-Yar Combine allowed normal teeming of rimmed steel in 50 ton ladles.To ensure a steady service of the stoppers in continuous steel casting the preheating of intermediate ladles of 1300 and the use of precooled stoppers are recommended.     

Wear of the periclase-lime lining of steel teeming ladles in ladle desulfurization of steel

Conclusions Wear of a periclase-lime steel teeming ladle refractory lining is a complex physicochemical process in which it is practically impossible to distinguish a predominant elementary direction of action of the molten slag and metal.Replacement of liquid synthetic slags with solid slag-forming mixtures in ladle desulfurization of steel does not have a significant influence on wear of the lining working layer.An increase in the amplitude and number of thermal cycles significantly increases formation of cracks in the refractory lining and, consequently, accelerates its wear. An increase in temperature gradient within the refractory layer significantly increases crack formation.The presence of high-temperature contact of the periclase-lime lining working layer with strong deoxidizers accelerates its wear.Reduction of the magnesium and calcium of the refractories by the carbon of the binder under ladle service conditions may occur only with escape of gaseous CO through the reinforcing layer and the joints of the refractory lining in special gas escape holes in the ladle shell.Translated from Ogneupory, No. 3, pp. 33–36, March, 1993.     

Upgrade of refractory lining of teeming ladles

A gradual upgrade of refractory lining of 160-ton teeming ladles, the disadvantages of the previous lining schemes, and methods for their elimination are described. The implementation of developed techniques has increased the resistance of teeming ladle lining by 60% (from 50 to 80 heats) and the consumption of refractory in the working layer of lining has decreased by 35.7% (from 4.79 to 3.08 kg/t of steel. __________ Translated from Novye Ogneupory, No. 7, pp. 18–19, July, 2007.     

Service of refractories in continuous casting of stainless steel

Conclusions Work was done on studying the service of refractories in continuous casting of stainless steel.It was established that refractories produced by domestic industry are suitable for this process and make it possible to obtain continuously cast billets in accordance with the requirements of TU 14-105-469-83. Gas protection of the stream of metal causes additional refining of the metal of nonmetallic inclusions and makes it possible to increase the quality of the cast billet.Stream treatment of the metal with inert gas makes it possible to significantly reduce encrustation of the nozzle channel with products of interaction of the molten metal with the refractory material of the ladle nozzle.Translated from Ogneupory, No. 6, pp. 52–55, June, 1985.     

An analysis of the temperature field in the refractory feeder of a horizontal continuous billet casting machine

Conclusions A mathematical model of the process of formation of the front of solidification of the billet skin in the refractory feeder of a horizontal continuous casting machine taking into consideration possible changes in the geometric and thermophysical parameters of the refractory has been developed.An algorithm and a program have been set up making it possible to calculate the temperature field in the refractory feeder taking into consideration the front of solidification of the billet skin. Using the program developed the temperature field was calculated for a graphite-containing refractory in teeming of 45 steel. The calculations made agree with experimental results on wear of the refractory.The data obtained makes it possible to explain the wear of the refractory in the zone of contact with the mold and also to optimize the configuration of the working portion of the horizontal continuous casting machine refractory feeder.Translated from Ogneupory, No. 6, pp. 36–40, June, 1988.     

Periclase-carbon composite refractories with a new complex binder

We describe the development of the technology of periclase-carbon composite refractories with a new complex binder, which combines the properties of phenolic resins and coal-tar pitch. Theoretical analysis and the results of application in steel teeming ladle lining show that a combination of these thermoreactive and thermoplastic components in the new binder provides a more compact (denser) structure of the coke framework (residue) possessing increased resistance to oxidation. Articles made of the new composite refractory have been successfully tested in the lining of steel teeming ladles. The wear characteristics of new lining materials in steel ladles has been studied. __________ Translated from Novye Ogneupory, No. 8, pp. 14–20, August, 2007.     

Unfired quartz nozzles for teeming of steel

Conclusions Unfired quartz nozzles hardened by hydrothermal treatment for teeming of steel are no poorer in life than fired. In addition in contact with aggresive (manganese) steels the wear of the unfired ceramic is somewhat less. There was no penetration of the unfired material by the products of interaction of the metal with the refractory during service.Unfired nozzles based on suspensions produced by grinding in an acid medium and stabilized in an alkaline medium showed the least wear in service.Translated from Ogneupory, No. 1, pp. pp. 39–43, January, 1989.     

用后铝碳质下滑板的显微结构研究

选取国内某钢厂使用3次后的下滑板残砖,利用扫描电子显微镜(SEM)、能谱(EDS)对滑板铸孔和板面用后侵蚀状况、显微结构变化和元素组成差异进行观察和分析。结果发现:下滑板反应层中形成了正八面体的铁铝尖晶石新结构;材料内部生成的纤维状碳化铝和颗粒状氧化铝能强化基质,提高抵抗熔渣侵蚀能力。     

Influence of the size of voids,impregnation with bakelite,and heat treatment of periclase plates on their properties and life in steel pouring ladle valves

Conclusions The relationship of the properties, the quality of the ground surface, and the wear resistance in service of the refractory plates in the gates of steel teeming ladles to the size and form of the voids, impregnation, and heat treatment of periclase plates was established.Translated from Ogneupory, No. 8, pp. 13–16, August, 1982.     

Insights into ZrO2- and Al2O3-based submerged entry nozzle clogging for the continuous casting of RE-treating sulfur resistant casing steel

The ZrO₂- and Al₂O₃-based submerged entry nozzle (SEN) clogging during continuous casting of a RE-treating sulfur resistant casing steel is studied experimentally based on morphological analysis and the related thermodynamic calculations. The results show that the ceramic cloggings exists both in the inner-wall and outlet regions of SEN, while the latter is the main reason for terminating the casting with its clogging reaching 77% in the nozzle cross section area. The clogging is caused by RE-containing inclusions from molten steel and reoxidation products by the reaction between RE in molten steel and the initial formed cloggings on nozzle refractory. The possible existence state of RE in molten steel with its content has been discussed, and the clogging mechanism studied in detail. To prevent nozzle clogging, suggestions are given for continuous casting of the RE-treating steel with a modified RE treatment strategy for less solid inclusions and solute [RE] presented in liquid steel during refining process. Additionally, the optimization of nozzle geometry and its refractory materials may help as well.     

滑动水口密封垫的试制与应用

以刚玉和膨胀石墨为主原料 ,粘土和热塑性树脂等为辅料 ,试制出气密性、高温膨胀性、抗侵蚀性和分离性优良的滑动水口密封垫。在钢厂的实际应用结果表明 :该密封垫的密封性和抗侵蚀性均较好 ,提高了上水口的使用寿命 ,增加了连铸的安全性 ;使用后不粘结水口与滑板 ,拆卸方便 ;使用效果与日本产品相当     

Steel contamination and growths on batching devices for continuous casting

Conclusions Delivery of metal with a closed jet facilitates a big reduction in the quantity of nonmetallic inclusions in the continuously cast ingot.By examining the kinetic rules governing the reaction of floating inclusions with circulation currents we established the optimum height of the molten steel level in the intermediate ladle as being equal to 600–650 mm.During the tightening of the nozzle, compounds enriched with alumina (highly dispersed refractory crystalline compounds of the corundum, mullite, and spinel type) are deposited on the walls of the channel.The higher the metal's concentration of inclusions containing large quantities of Al₂O₃, then the more intense is their bonding with the refractory, leading to tightening up and growth of the nozzle.Translated from Ogneupory, No. 8, pp. 22–27, August, 1970.     

Development of refractory ceramics from residual silica derived from rice husk ash

Rice husk has been used as a thermal energy source for electricity generation, resulting in the formation of silica from rice husk as a by-product. This research aims to develop refractory ceramic materials by replacing kaolin clay with rice husk silica at 5%, 10% and 20% volume percentages. The samples were investigated in terms of their density, apparent porosity, tensile strength in three-point bending test, compressive strength, thermal shock and mineralogical composition. The use of 20% silica resulted in an increase in the formation of cristobalite, higher packing of granular mixtures, and consequently, an improvement in the tensile strength and compression strength of the samples. However, the material that was most successful in increasing the mechanical strength without decreasing the thermal shock strength was the sample processed with 10% clay replacement by silica from rice husk.     

Corrosion mechanism of lightweight microporous alumina-based refractory by molten steel

Lightweight refractory linings for industrial furnaces have become important subjects of development in high-temperature industries. The reaction mechanism between a lightweight microporous alumina-based refractory material and molten steel was investigated in this study. The main mechanism of refractory damage was structural spalling, caused by steel penetrating the pores. The many micropores in lightweight microporous alumina have high specific surface area and reactivity, inducing the formation of FeO–Fe₂O₃–Al₂O₃ phases. This impeded the further penetration of molten steel and the direct dissolution of refractory oxides, promoting greater resistance to molten steel than that shown by common tabular alumina-based refractories, in which Fe does not react and steel penetration through the pores cannot be retarded.     

Refractory clays of Stepnyi deposit

Conclusions The investigated sample of Stepnyi deposit clay is suitable for production of type ShA normal-purpose chamotte parts. The use of this clay in the production of certain forms of chamotte parts such as bottom teeming, open hearth, and other parts is possible. Being quite plastic, such clays may serve as a binder refractory raw material and be used for production of more critical parts in combination with chamotte from more refractory clays (bauxite and others). Chamotte of Stepnyi deposit clay may be used in combination with enriched Eltai kaolin. This in full measure refers to Stepnyi deposit clays of the better grades corresponding to types VGO-1 and VGM. Taking into consideration the low content of the coloring oxides, Stepnyi deposit clays may also be used as a white-firing raw material in the production of various ceramics.Translated from Ogneupory, No. 4, pp. 24–26, April, 1993.     

Ultrasonic quality control of gate plate bases

An experimental prototype of a commercial ultrasonic device for quality control of fired bases of PSP-96-type refractory plates for sliding gates of steel teeming ladles is presented. The device is based on the ultrasonic shadow method. It is demonstrated that ultrasonic monitoring efficiently reveals hidden cracks in the fired plate bases and reliably excludes the possibility that serviceable articles would be rejected. Translated from Ogneupory i Tekhnicheskaya Keramika, No. 4, pp. 23–24, April, 1997.