This article examines the three stages in the development of slide-gate systems. The modern slide gate is characterized by the presence of elastic elements and reliable fastening of the plates. Different methods are discussed for securing the refractory plates in the carriage of the slide gate. Reliable operation of the gate is provided by the drive and auxiliary elements designed with allowance for the specific features of the casting of metal with the use of slide gates. Hydraulic drives have proven to be the most effective drives in Russia and abroad. The article also discusses the shapes of refractory slide-gate plates that help reduce crack propagation and make the plates more reliable in service. The latest generation of slide-gate plates is now in wide use, these plates being made with carbon-based, oxygen-free, or cermet binders.A slide-gate system is a complex of production equipment, auxiliary equipment and refractory elements that allows metal to be cast through a slide gate. The system includes slide gates for steel-pouring ladles and tundishes, a drive mechanism and feed devices, and auxiliary equipment and materials (molds, mortars, fillers, etc.). The introduction of slide-gate systems has been characterized by three stages of development. First Generation of Slide-Gate Systems (1965 -1980)The refractory systems of this generation allowed the casting of just a single heat [1]. The slide gate -a massive structure weighing 500 -1000 kg -was made in auxiliary shops. The gate designs were of the "rigid" type and the plates comprising the gate were pressed against one another by bolts. The plates were installed in the gate with the use of a mortar. They were serviced in special shops, and it was necessary to maintain a large stock of reserve gates. The service life of a gate was 70 -100 heats. It took more than 2 h to replace the refractories in the casting unit. Each metallurgical plant developed its own design of drive (hydraulic, pneumatic, or electrical) without regard for the details of the casting operation itself.The characteristic features of the plates used for the first generation of slide gates were as follows:-the use of plate materials with a single-component composition based on fused or sintered periclase, mullite, corundum, zircon, or other material;-the use of unconcentrated raw materials; -the use of a ceramic binder; -partial alloying of the plate material with refractory oxides to improve certain properties (Cr 2 O 3 was used to reduce the wettability of the surface of the metal, ZrO 2 was used to improve heat resistance, etc.); -impregnation of the plates with carbon-bearing liquids (coal-tar pitch, liquid bakelite, etc.); -the use of a coarse porous structure in which 70 -75% of the pores were 20 -30 mm in size and 20 -25% were smaller than 1 mm; the presence of individual pores with a size in the range 40 -70 mm contributed to significant wear of the plates;-the absence of metal casings and the use of a system of mortars to join the refractories together.Most of the plates in the ...
Basic principles are considered for the development of refractory linings for steel-pouring ladles operating under severe conditions using a furnace-ladle unit. Joint action of personnel of the metallurgical enterprise and refractory supplier makes it possible to determine the local area of lining wear and to adopt timely measures for improving life. The effect of the main factors governing wear is determined. The order of selecting the required standard sizes and quality indices for objects taking account of the type of metal smelted is determined.Keywords: refractory lining, slag belt, local wear.As a result of technical progress in the field of refractory production the possibility has developed not only of improving metal quality, but also reducing expenditure connected with steel-pouring ladle lining operation, in particular those operating under conditions of furnace-ladle installations and metal evacuation.Refractory consumption for lining ladles in metallurgical enterprises with a complete cycle is about one quarter of all refractory consumption (in absolute value and cost) [1]. The overall expenditure for traditional ladle refractories in the cots of Russian metal was previously 1.5 -2.0%, and therefore a insufficient attention has been devoted used to saving refractories. A long life for a lining has a marked effect the non-metallic inclusion content in metal.Currently the expenditure on acquiring contemporary refractories is 4 -7% of metal cost. An increase in metal cost may be balanced by a reduction in specific refractory consumption due to the use of modern methods for lining operation and new standard sizes for refractory objects.For effective operation of carbon-containing refractories it is necessary to have a high-temperature unit for warming up refractories. A lining warm-up unit may be horizontal or vertical. Expenditure in installing a high-temperature unit is repaid in 6 -8 months. Each uint is equipped with a heat-protective cover in order to avoid heat loss during pouring.The carbon-containing composition refractories used in contemporary linings do not exhibit high heat resistance and during operation they should not be cooled to lower than 800°C. With presence in some cycles of cooling below 800°C there may be some reduction in lining life.The life of refractory linings used in furnace-ladle devices is determined by a group of factors, each of which should be considered in lining operation. These are factors connected with refractory properties, lining construction, and pouring technology.In the presence of high quality refractories it is not always possible to achieve maximum lining life. Even insignificant changes in metal smelting technology and pouring may lead to a reduction in refractory life. EFFECT OF REFRACTORY QUALITY ON LINING LIFE Refractories usedIn contemporary linings there is mainly use of carbon-containing refractories based on periclase-carbon or aluminopericlase-carbon composition. Some Russian enterprises manufacture these refractories based on imported Chinese raw ma...
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