O-air 2 at 298 -2400 K applied to the behavior of carbonized periclase refractories under production and operating conditions. Partial and total pressure, developed by gaseous reaction products of material with an average pore space (CO 2 , CO, CH 4 , H 2 O, H 2 , etc.) are determined in relation to pressure. The effect of gasification for the carbon component, porosity, original and atmospheric moisture, that is not currently subject to experimental observation, are considered.
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...
The properties of Chinese natural graphite of grades FG+194 and FG+198 and their ashes are investigated. The extent of the effect of ash content in graphite on the technical parameters of carbonized periclase refractories with an increased carbon content is demonstrated. The advisability of using low-ash graphite for carbon-bearing refractories is justified.The refractory lining in metallurgical aggregates functions under the intense impact of high temperatures, aggressive gaseous media, and thermomechanical loads. The intensification of metallurgical processes calls for new solutions that could upgrade carbon-bearing refractories and extend their service life.The Department of Chemical Engineering of High-Temperature Materials at the St. Petersburg Technological Institute has substantiated and keeps refining the parameters of producing a new type of carbonized periclase refractory with a wide spectrum of carbon content (6 -22 wt.%), which ensures a high level of physicotechnical properties [1]. Optimization of the material and phase compositions, microstructure, and technological parameters of functional carbonized periclase refractories makes it possible to achieve high thermomechanical properties and high resistance to degradation processes [2]. The most significant service characteristics of such refractories exceed those of the existing analogs and offer a high competitive potential on the refractory market.The developed promising carbonized periclase products are intended to line steel-casting ladles, ladle-furnace plants, bay window elements in electric steel-melting furnaces, and combined brickwork for converter lining with an extended service life. Depending on the quantity of the carbonaceous additive, the properties of periclase carbonized refractories vary within a wide range, which ought to be used in determining the functional purpose of the product in the structure of lining. For metallurgical aggregate zones with a high level of mechanical loads the most suitable are refractories containing up to 12 wt.% carbon, whereas compositions with an increased carbon content are preferable for high temperature gradients and high slag loads. However, an increased content of the graphite additive decreases the resistance of refractories to oxidation. Technologically, the production of carbonized periclase products (graphite content > 12 wt.%) is the most difficult. Mixtures for such refractories involve much air; therefore, the mold in the course of molding requires special ventilation, in particular, vacuum treatment. The choice of an appropriate composition of the main components in the periclase-graphite mixture that would be justifiable with respect to the cost/quality/properties ratio remains a topical problem.The production of carbonized periclase refractories uses high-quality materials: melted periclase (MgO ³ 97%, CaO/SiO 2 ³ 2), high-purity coarse-scale natural graphite (C ³ 94%). The carbon phase is dissolved in steel melts, but significantly increases the resistance of the refractories to melted p...
A technology has been developed and implemented for producing joint-free continuous taphole blocks for steel-tapping units of large-size converters using hydrostatic molding. The functional parameters and properties of these taphole monoblocks are not inferior to imported analogs.Contemporary metallurgy is oriented to intensification and the development of new methods for producing top-grade steel. Oxygen converters and steel melting in electric furnaces are now predominantly used in the domestic and world practice. The intensification of metallurgical processes imposes more stringent conditions on refractory lining in metallurgical plants. The world practice of converter service shows that to achieve efficient use of lining and cost-effective steel melting, the brickwork in different zones of a converter should be balanced taking into account the service conditions and loads peculiar for each zone.One of the lining units experiencing the most intense wear is the refractory taphole block in the steel-tapping unit. The high temperature of tapped metal (up to 1800°C) accelerates the taphole wear [1]. The refractory material of the taphole undergoes extreme thermal and thermomechanical loads together with the erosion and corrosion effect of the metal and slag melts, which in combination produces degradation of the refractory microstructure, erosion of the matrix grains from the taphole block, and cracking and spalling, which is the most dangerous type of destruction. Replacing a taphole block takes a long time, which leads to additional cooling of the converter lining and extends the idle time of the steel-melting plant [2]. Increasing the resistance of the tapping channel and extending its service life remains a topical and urgent problem.The service life of the critical metallurgical lining units (including converter tapholes) can be extended using largesize continuous joint-free periclase-carbon refractories that have extended service life and are relatively easy to install, repair, or reline. The Russian refractory market offers imported monoblock tapholes [3]. This is mainly due to the fact that the leading domestic producers of refractories lack the experience and complicated machinery and technologies needed for the industrial production of large-size monolithic products.Periclase-carbon taphole blocks contain effective antioxidizing additives which raise the resistance of the carbon component to oxidation, as well as heat and slag resistance, and improve the strength parameters of the products [1]. The use of metallic magnesium and certain boron compounds improves the resistance of MgO-C steel-tapping products to abrasive wear. It is established that the use of these powders and finely dispersed scaly graphite improves corrosion and thermal cracking resistance. The wear rate in this case decreases from 0.2 to 0.12 mm per heat and the refractory cost for the consumer drops by about 20% [4].Among various methods for producing large-size carbon-bearing periclase blocks (molding on friction and hydraulic presses...
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