In recent years in the metallurgical plants of the country greater use is being made of monolithic rammed linings of steel-teeming ladles made with the use of sand slingers. Conversion of teeming ladles with a brick lining to a rammed lining makes it possible to increase the length of their campaign and to reduce the consumptionof ladle refractories and the costs of manual labor in lining work [1][2][3].In the open hearth shop of the Makeevka Metallurgical Combine the method of rammed llnings of the walls of 250~ton teeming ladles with the use of a UP-250 sand slinger designed by the All-Unlon Scientific-Research Institute for Mechanization in Ferrous Metallurgy has been introduced and mastered. The sand slinger is equipped with two throwing heads with a capacity of 60 mS/h of rammed mixture. The rate of rotation of the throwing head is 1490 rpm, the exit rate of the material 63 m/sec, and the rate of rotation of the sand-slinger platform controllable from 2 to 9 rpm. The machine time for ramming the lining of the walls of a single ladle (without auxiliary time) is 15-25 min.For the rammed lining of the ladles type MKG-I quartzite--clay mixture to Technical Specification 14-8-252--77 developed by the Ukrainian Scientific-Research Institute for Refractories and produced by Krasnogorovka Refractory Plant is used. The thickness of the rammed lining at the top of the ladle is 160-180 nun and at the bottom 190-220 nun. The consumption of ramming mixture for a single ladle is 21-22 tons. Practically uniform ramming over the height and perimeter of the ladle is obtained with a rate of rotation of the sand slinger platform of 6-7 rpm for the bottom of the ladle and 5-6 rpm for the top. The surface hardness of the rammed lining measured with a Model 071 hardness tester is 85 • 5 units.The rammed linings are~dried on special stands with the bottom of the ladle down with natural gas with a pressure of 0.3-0.4 MPa with a lO0-mm-diameter single line gas burner placed in the ladle to a depth of 2000 mm. To improve removal of moisture from the rammed lining in drying 12-mm-diameter steam holes located in checkerboard order with a spacing of 300-700 mm were drilled in the metal shells of the ladles. Eighty-four holes are drilled in the shell of a single ladle.With the use of KhA thermoelectric calibration transducers in combination with a KSP-4 secondary recorder, the optimum drying cycle was developed for the rammed ladle linings. The thermoelectric transducers were installed through the steam holes at the boundary between the brick reinforcing lining (base) and the rammed lining, in the center of the rammed lining, and 30-40 mm from the working surface at distances of i000, 2500, and 4000 mm from the bottom. Reaching of a temperature of ii0 • 10~ at the boundary between the reinforcing lining and the rammed layer was taken as the criterion of satisfactory drying. Satisfactory drying (without spalls, cracks, and collapsing of the lining) with the use of the burner equipment available in the shop was reached in 19-21 h with the ...

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The high multilayer charge in which refractory parts are fired is frequently the reason for formation of scrap and significant variations in the properties of refractories. In connection with this possibility of use of a roller kiln with single-layer firing for bottom pouring tubes was studied.In our country roller kilns are used primarily for firing of ceramic plates. Designs of such kilns are known [i, for example].At Konstantinovka Refractory Plant an SMK-158 roller kiln produced in Constructional Material Production Machinery Plant, Mogilev-Podol'skii has been built. The necessary changes and additions taking into consideration the product being fired have been introduced into the design of the roller kiln. The kiln includes a dryer. A single roller conveyer driven in sections by six drives was the means of movement. The rollers are driven on both sides by sprocket chains. To each roller is fastened a drive sprocket. The driving branch of the chain is located above the sprockets. Above the chain are located clamping strips. The rollers rotate in sleeves.The roller dryer consists of four similar sections with a length of 9 m each. Each section is a metal frame covered on the outside with steel plate. The lining of the walls, the hearth, and the roof is made of thermal insulation materials and chamotte brick. In the walls in a checkerboard arrangement on both sides there are hatches with doors for cleaning the hearth. Each section is equipped with 12 inj'ection burners located under the conveyer in checkerboard order. There is also a system for utilization of the stack gas heat, for which the manifold of each section is connected by an individual pipe with a controlling slide valve to the centrifugal fan removing the stack gases from the kiln. To remove the stack gases in the roof of each section there are exhaust manifolds connected by a pipe with a controlling slide valve to the common stack.The roller kiln consists of 24 3-m sections (positions) located on the frame of the roller conveyer. Between the sections there is a 20 mm gap filled with asbestos cord serving as a temperature joint. Rollers with a length of 2150 mm, a diameter of 32 mm, and a spacing of 70 mm pass through holes in the walls. The width of the kiln channel is 1150 mm and the height in the firing zone from the learth level to the peak of the roof 750 mm.To fire the kiln channel 157 gas injection burners are located over the whole length of the roller kiln in both sides in the walls in checkerboard order. In the heating and firing zones the burners are located above and below the roller conveyer. Under normal conditions the consumption of natural gas is ii0 m3/h. The stick gases are removed from the kiln through holes in the roof and directed to the dryer. The quantity of gases removed by positions of the kiln is regulated by slide gates.At the level of the hearth in each section there are four hatches, two on a side, in checkerboard order and two peepholes above the rollers to observe the working space.Lightweight and normal chamotte mater...

621,783,2-2-033,76:66,044.24 Refractories in furnaces for heating of steel billets for rolling of them are subjected to the action of high temperature, mechanical failure related to movement of the billets, thermal shocks in cooling and heating of the furnaces during the time of preventive maintenance of the mills and loading and unloading of the metal, and the slag corroding action of the scale [i, 2].As a rule the roofs of heating furnaces are made suspended with the use of types ShA and ShB shaped chamotte parts to GOST 390-83 and the working layer of the walls of types ShA and ShB chamotte brick of standard sizes.Occasionally the lining of the working layer of the walls of the high-temperature zones (soaking, welding) is laid with type KhM-I chromitepericlase brick to GOST 5381-72.An analysis of the long service of the lining of the pusher heating furnaces of five shape mills (250, 300, 350) of the Makeevka Metallurgical Combine indicates significant nonuniformity of its wear.The roof and wall refractories in the soaking and welding zones, where spalls, peeling, and crumbling of the brick for a length of 30-50 mm and more are observed, wear the most.Also noted are cases of falling off of the roof refractories as the result of deformation or burning of the metal suspensions under the action of hot flue gases passing through breaks in the lining.The surface of the lining, particularly of the burner and division walls and the roofs in the soaking zones, was covered with a layer of scale 5-30 mm thick.The wear of the furnace wall lining is related primarily to its mechanical failure and interaction with the scale, and of the roof lining to thermal shocks of the lining caused by rapid cooling and heating of the furnaces in shutting down of the mills for preventive maintenance, inflow of cold air in the area of unloading of the metal, and also the interaction of it with the scale.After service in heating furnaces (9-12 months) chamotte refractories have a zonal structure with four or five visible zones observed.* In the transition zones an increase in the weight share of iron oxide (to 3-4%), growth of the mullite crystals (from 12-15 to 45-47 ~m), and an increase in the quantity of cracks and pores and also in their size not only at the contact with the binder but also within the base material are noted In the working zones the weight share of iron oxide reaches 8-10%, which reduces their refractoriness, for example, from 1730-1740 to 1660-1670~ for type ShA parts, In the binder there is an increase in the content of glassy substance and in its refractive index (Nav= 1,592-1.600).The slag crusts of the refractories after service are primarily isometric tabular from dark green to dark grayish brown magnetite crystals of spinellides of complex composition up to 14-15 ~m in size cemented with a glassy substance with Nav= 1.500-1,544, Therefore in the service of chamotte parts in the high-temperature zones of heating furnaces a transformation of them related to a change in the structure and mineral and chemical co...

In recent years mechanized guniting of the lining of steel teeming ladles has found ever increasing use in the plants of the Ministry of Ferrous Metallurgy of the USSR. This has been aided by the presence in plants of mechanized equipment (the Orion type, an attachment to the Orbit sand slinger, the designs of Krivoi Rog Steel and Zaporozhe Steel Combines, etc.) and the organization in Novoselitsa and Kondrat'ev Refractory Plants of the production of guniting powders in ready for use form. The guniting equipment is serviced by two men, operators of the Orion-i machine and of the SB-67A guniting machine.In development of the optimum guniting parameters type PShGT-2 chamotte-clay guniting powder to Technical Specification 14-8-265-78 produced by Kondrat'ev Refractory Plant with not less than 37 wt. % of AI=O 3 of the 2-O-mm fraction, including 20-30% of the finer than 0.09-mm fraction, was used. An aqueous solution of water glass with a modulus of 2.8-3.0 and a density of 1.10-1.22 g/cm s prepared in the combine was used as the binder and moistener.The guniting parameters were varied within the following limits: pressure of the air transporting the guniting powder from 0.27 to 0.35 MPa; pressure of the binder and moistener Ukrainian Scientific-Research Institute for Refractories. Makeevka Metallurgical Combine.