Results are provided for the development and introduction into production of high-alumina objects of different grades based on andalusite. Physiochemical indices, and fields of application for objects in various heating units are indicated.High-alumina refractories are some of the most used. Traditional high-alumina materials, prepared on the basis of alumina or bauxite, do not respond to the contemporary level of requirements for reliability and endurance. A solution of this problem is production of new refractories based on andalusite. Such qualities of andalusite as high purity, sufficient volumetric stability, low porosity, active mullitization, low thermal conductivity, give rise to its use in producing high quality refractories [1].The preference for using andalusite within the composition of refractory objects compared with high-alumina chamotte is due to the physicochemical features of this material. Andalusite is a natural "mullite former". During hightemperature firing it is converted into mullite, and the excess silica forms a comparatively small amount of glass phase, exhibiting high porosity, and it is concentrated in capillary pores of a grain [2] (Fig. 1). Thus, after firing of refractory based on andalusite it becomes and entirely new material, consisting of primary and secondary mullite and a small amount of highly bonded glass phase, that provides new refractory properties incomparable with those of high-alumina refractories of other forms.Currently for lining air coolers and the bottom glass furnaces, lining steel-pouring ladles, mobile mixers and anode firing furnaces, there is extensive use of domestic mullite and mullite-corundum grades MKV-72, MLS-62, MKS-72, MLLD, based on high-alumina chamotte, prepared from alumina and kaolin. For these refractories there is typically a significant amount of glass (Fig. 2a ) exhibiting reduced toughness at high temperature and nonuniform distribution, that promotes a reduction the high-temperature strength of objects under load, low resistance to cracking due to microstress development, that arises during thermal shock.Specialists of OAO BKO have developed and introduced into production high-alumina objects grade MLUT-62, MLUT-69, MKP-72, manufactured on the basis of andalusite. Objects may be used for lining mobile mixers, iron-carrying and steel-pouring ladles, the upper cone and upper part of the shaft of a blast furnace, and also anode firing furnaces
With the advent of the new century, considering the situation on the market of refractories and the competitiveness of domestic products, the Borovichskii Refractory Works (BRW) company has decided to set up its own powerful research and experimental base. As the result, the Center for Technology and Production Upgrade (CTPU) has been set up at the BRW. This self-contained division has successfully performed for 5 years; it is responsible for the development of new technologies and upgrade of the existing ones. The CTPU is equipped with state-of-the art equipment for extensive tests, analyses, and experiments ( Fig. 1): determination of compression and bending strength, density, porosity, heat resistance, thermal conductivity, refractoriness, temperature of deformation under a load, creep, etc.The CTPU has three main departments: the ResearchTechnological department responsible for the developments in the area of refractory technology; the Engineering Department, which actively cooperates with companies that are customers of the BRW products and carries out quality control; and the Department of Physicochemical and Physicomechanical Testing with competent staff capable of carrying out specialized studies.The CTPU maintains close relations with the St. Petersburg Technological Institute (Technical University) in research and professional training of the personnel. Every year specialists of the CTPU participate in seminars and conferences.The Department of Physicochemical and Physicomechanical Testing includes the laboratories of chemical, x-ray, thermogravimetric, differential thermal, and microscopic analysis, and physicomechanical and thermal tests. It is capable of performing fast and high-quality analysis of the feedstock and products of the company at any technological stage, controlling and optimizing technological processes in production of refractories, performing tests to determine and correct the physicochemical and mechanical properties of samples and products. These data obtained using a combination of physicochemical methods make it possible to adjust the batch and fractional composition, the raw materials used, the firing temperature, and other technological parameters. An important aspect in the activity of this department is the development of new technologies and upgrade of the existing ones. This department is also responsible for analyzing variations in the physical and mechanical properties of products in testing or in service.The laboratory of physicochemical and thermal tests determines the following parameters: thermal conductivity of refractories by the stationary method:-determination range from 0.13 to 15 W/(m · K); -the temperature on the hot side of the sample from 400 to 1350°C; coefficient of linear temperature expansion and relative expansion of samples on a horizontal high-temperature dilatometer Netzsch:-atmosphere: vacuum, gas, or air; -temperature range 20 -1600°C; -sample length range 25 -50 mm; -ability to test viscous and powdered samples; -computerized programming and process...
Under electric steel smelting workshop (ESSW) OAO Volzhskii Pipe Plant operating conditions the evolution of design and life of oxide-carbon refractories produced and supplied by OAO BKO in the period 2004 -2008 is followed. Operation of the working refractory lining layer of 150-ton steel-pouring ladles of ESSW furnace-ladles is analyzed, and the main areas for improving refractory composition and lining design are determined.The electric steel smelting workshop (ESSW) of OAO Volzhskii Pipe Plant (OAO VTZ) with a capacity of 900 thousand tons of steel per year provides the requirement of the enterprise for steel pipe manufacture. The modern electric steel smelting equipment includes the following units: an arc steel smelting furnace with a melt weight of 150 tons, water-cooled panels and roof, window delivery of metal; two furnace-ladle units (FLU) for finishing melt with respect to chemical composition and temperature with introduction of artificial slag and blowing with argon; a yard for steel-pouring ladles with a capacity of 150 tons in an amount of seventeen units; a steel vacuum degassing installation (VD-process); three four-stream units for continuous billet casting of the curvilinear type. Use of advanced technology and highly efficient equipment makes it possible to obtain high quality steel billets with an ultralow content of harmful impurities and gases.After introduction in 2000 of an oxide-carbon lining for steel-pouring ladles specialists of OAO VTZ started to attempt to improve the quality specifications for smelted steel and to reduce its cost. Intensification of production operations and steel processing under ESSW OAO VTZ conditions (argon blowing, steel vacuum degassing) lining service conditions in metallurgical units became complicated. The process of vacuum degassing of steel, active movement of metal and slag as a result of bottom blowing, created particularly severe service conditions for refractories in steel-pouring ladles, caused intense action on the oxide-carbon linings of a high temperature (up to 1720°C), corrosive molten slags, variable gas atmospheres, and increased thermomechanical loads. The requirement for completion of alloying, deoxidation, homogenizing metal with respect to chemical composition and temperature markedly increased the metal dwell time in ladles.Expenditure on repair and assembly of linings was a considerable part of the cost of pipe steel production. A reduction in specific expenditure in the consumption of refractory materials and an increase in the service life of linings of metallurgical units will make it possible to increase the operating efficiency of ESSW OAO VTZ. An increase in the life of trouble-free operation of linings is provided by improved technology and increasing the technical property indices and quality of refractories used, continuous observation of the design of the lining of the working layer providing uniform wear of all lining elements.The scientific and practical research center for improving technology and production (TsSTiP) of OAO...
In the OAO Borovich Refractory Combine production has been assimilated for a complete set of refractories for continuous steel casting, i.e. from a pipe for protecting a stream of metal to a submerged nozzle. In technical and life characteristics the products correspond to that of world analogs, they provide accident free steel pouring, make it possible to reduce the specific consumption of refractories per ton of steel, to increase CBCM productivity, to reduce billet scrap, and to reduce steel cost.An increase in the proportion of steel continuous casting within the general volume of steel billet production and the complication of metallurgical processes is associated with an increase in the role of refractories not only from a technical, but also from an economic point of view. Refractories of a new generation for metallurgical production should exhibit high mechanical strength, high erosion and corrosion resistance properties under operating conditions at high temperature in media of a different chemical nature (melts, slags, etc.), wear resistance (including hydrodynamic effects), heat resistance etc. Use of these refractories will make it possible to reduce their specific consumption per ton of steel, to increase CBCM productivity, to reduce billet scrap, and to reduce steel cost.Due to the competent innovation policy and correct distribution of resources for providing the increasing requirements of metallurgists OAO Borovich Refractory Combine (BKO) under its own efforts and drawing on outside specialists is carrying out work for improving the manufacturing technology of articles for continuous steel casting with the aim of increasing their life. The Combine has bought expensive equipment that makes it possible to determine a set of service characteristics and refractory properties, with considerable reliability for predicting article life for customers. The list of refractory products monitored and standard quality indices is constantly expanding.OAO Borovich Refractory Combine produces a whole set of refractories for continuous steel casting: pipes for protecting the metal jet from secondary oxidation in the area of the steel pouring ladle, i.e. CBCM intermediate ladle, articles and mixes for the control and working lining of an intermediate ladle,articles for organizing metal flow into the intermediate ladle,stopper-monoblocks, dispenser nozzles, submersed nozzles. PIPES FOR PROTECTING THE METAL STREAM FROM SECONDARY OXIDATIONIn order to protect the metal stream from secondary oxidation in the area of the steel-pouring ladle, i.e. the intermediate ladle, there is traditionally use of pipes of corundum composition. OAO BKO has assimilated production of corundum-graphite pipes for protecting the metal stream grades TKG and TKGU (Table 1). The articles are manufactured by innovative technology on the basis of powders of fuzed corundum of different fractions, graphite and special additions that increase the heat resistance and wear resistance of articles. In order to provide the required article life for gra...
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