No abstract

At the Dzerzhinskii Dnepropetrovsk Metallurgical Combine a converter shop has been placed in service.In this shop the steel is top teemed into 5.5-8.8-ton ingots from 250-ton ladles equipped with slide gates.After tapping into the ladle the molten steel is blown with argon for 5-15 min depending upon the temperature of the metal.The slide gate used in the shop has a rigid construction (Fig. i).In the lining of the ladle 1 is made a depression into which is placed a pattern in the form of the nozzle and the depression is rammed.After drying the ladle nozzle 2 is placed in the rammed depression.The upper stationary plate 3 and the movable plate 4 with the lower nozzle are in contact with the Collector 5. All of the refractory parts other than the nozzle are located in a metal case and they are installed on the ladle in the form of separately assembled unit.The unit is fastened to the flange 6, which is welded to the bottom of the ladle and the holder 7 is the supporting part for the whole block.The upper plate of the gate is installed with refractory cement in the depression of the holder 7. The gate is fastened on the pins 9 to the flange 6 by the four wedges 8. The plates 3 and 4 are clamped to one another by the four bolts 10 and nuts ii of the plan 12 through the intermediate support 13 by an adjusting unit.The wedges 15 are placed in the pins 14 and the lower nozzle holder 16 is fastened by them to the pan 12. Before assembly the holder 7 and the pan 12 with the refractories placed in them with cement is dried in electric furnaces at 200-250~The ladles are equipped with two slide gates.The metal is teemed alternately, the first heat through one gate and the second through the other.In the gates No. 18 nozzles and No. 25 lower nozzles of unfired magnesite produced by Panteleimonovka Refractory Plant and also No. 10 magnesite plates with periclase inserts produced by Vnukovo Refractory Part Plant and Nikitovskii Dolomite Plant were used.* The MgO content in the plates of Vnukovo Refractory Part Plant was 97.9 wt.% and in the plates of Nikitovskii Dolomite Plant 95.6 wt.% and the Fe20 s content was 0.3 and 0.53%, respectively.The use of mullite-corundum plates of Chasov Yar Refractory Combine was tested. The AI20 s content in them was 90.02 wt.%, the Fe20 s content 0.70 wt.%, and the compressive strength 125 N/mm = .The inserts and the mullite-corundum plates were impregnated with bakelite lacquer. The diameters of the holes in the refractories were 70mm in the nozzle, 60 mm in the plates, and 55 mm in the lower nozzle.The refractory plates, the lower nozzles, and the nozzles were made of refractory compound.Before assembly the plates were carefully lapped and coated with graphite-oil emulsion.The working surfaces of the plates were clamped with four screws to which was applied to torsional moment of 80 N'm per screw.The space between tlhe ladle lining and the nozzle was rammed with refractory compound.After drying of the rammed depressions and installation of the nozzles the metal conducting channels were filled...

High-speed steelcasting in a well-formed Jet requires the use of nozzles with a largediameter channel of complex configuration. Nozzles of this type with the necessary physicomechanical properties are difficult to produce owing to the inadequate power of the presses at some of the establishments of the refractories industry. A modification of the presses made it possible to produce nozzles with a channel diameter of 80 mm. The difficultles involved in the manufacture of nozzles with channels 100-120 nun in diameter of complex configuration prevents them from being produced on a large scale.In recent times other methods of manufacturing refractory products, e.g., for steelcasting, have been developed among them that of casting them from free-flowlng alr-drylng granular compositions with a technological binder, e.g., orthosilicic acid ester (ethylsillcare) [1][2][3][4].With this method the use of a plasticizer which in some cases has an adverse influence on the properties is dispensed with and the pressing operation is elimlnated; the outlays on the manufacture and servicing of the forming equipment which in pressure molding wears rapidly as a result of the high specific pressure and the abrasive action of the molding composition are lower; complex-configuration products can be formed; and thermal-shock resistance of the product is high owing to the nature of the macrostructure of the casting.The planned flow sheet for the manufacture of refractory products from free-flowing, alr-hardenlng, ethylsilicate-bonded granular compositions (Fig. I) is simple and convenient in practical use.In order to assess the suitability of this method for the production of steelcasting nozzles, to refine the technology, and to study the performance of the refractories in service, an experimental batch of cast Ts/SP-23-80 type nozzles were produced at the Krasnoarmelsk Dines Plant by a simplified flow sheet (i.e., using a very simple vibrating table and paddle mixer).* The nozzles were produced from a mix of the following composition: 25 • i% ground zircon brick of particle size 0.5-3.0 mm, 25 • i% the same material but of particles size smaller than 0.5 mm, iron-free zircon concentrate finer than 0.06 mm, and ii • 0.5% binder (hydrolized ethylsilicate consisting of 40% distilled water, 60% ethylsilicate~ and 0.8% hydrochloric acid solution on 100%).The ethylsillcate was hydrolyzed in a high-speed paddle mixer (paddle speed --2600 rpm). The process was considered complete when the temperature of the solution had fallen to 20~ after which the solution was rested for 8 h.The filler (refractory material) was prepared by the usuaI method.To increase the density and strength of the products the zlrcon-briquet powder was treated with sodium methylsillconate which accelerates the coagulation and polymerization of the products of the hydrolysis of the ethylsilicate. The amount of added coagulant was 0.2% on the weight of the filler.The free-flowing composition was also prepared in a paddle mixer in the following sequence: one-third of the flne...