Refractories and lndustriai Ceramics ~%L 3,~. ,Vos. 3- 4, 1997 PRODUCTION L,-DK 621.746.587.073 DOUBLE-LAYER RUNNER BUSHES FOR THE THERMAL INSULATION OF STEEL FEEDHEADS V. P. Nemchenko, l V. G. Mamaeva, 1 M. Z. Nagmskil," E. V. Nazarova," L. V. Panova, z and Y. S. Braslavskaya 3 Translated from Ogneupory i Yekhnicheskaya Keramika, No. 4, p. 30. April, 1997. Original article submitted January 14. 1997. Some features of the production and use of double-layer (sand-cellulose composite plus kaolin) runner bushes for the thermal insulation of steel feedheads are considered. Use of the double-layer bushes during transtbrmer steel casting in ingot molds gave positive results. At present, a considerable proportion of the ingots of The double-layer bushes are fabricated using a mold. killed steel are obtained in open-bottom ingot molds without First, the mold is filled with a sand-cellulose hydromass based on a slip composed of 76 - 80% sand, 5.5 - 6.5% clay, runner bushes, using sand-cellulose thermal-insulation insets and 5.6 - 6.5% technical-~ade lignosulfonate. Upon leveling (SCI). The comparatively high density (~ 1.2 g/cm 3 ) and of the first layer, the second slip layer is applied, comprised thermal conductivity [0.6 W/(m. K)] reduce the efficiency of of 92- 96% kaolin wool and 4-8% binder. The plate is these insets. For example, use of SCI plates with dimensions formed by water removal from the hydromass (by vacuum of 40 x 500 x 550 mm in the production of 13-ton ingots of suction via the underlying grid) accompanied by pressing with transformer steel at a plant of the Mechel Company stipulates the top plunger with a pressure of 4 MPa. The as-pressed bu- a rather large feedhead cut (15%), but even a~er that the un- shes are dried for 24 h at 140 - 160~ in a counter-flow drier. derhead edges on many ingots exhibit spilling. Another dis- The dry bushes with dimensions of 40 x 500 � 550 mm advantage of SCI, manifested upon strippering the ingots, are composed of~,o layers (each 20 mm thick) and are char- consists in the considerable sand pouring, detrimentally af- acterized by the following parameters: fecting the sanitary working conditions for the personnel. Much lower values of density (0.2 - 0.4 g/cm 3 ) and ther- Apparent density., g/cm "~ ............. 0.82 - 1.0 mal conductivity [-0.23 W/(m-K)] are offered by plates Ultimate bending strength made of kaolinite wool. However, numerous experiments (not less than), MPa .................. 0.5 conducted at the Dinur and Mechel Companies showed that Gas permeability, gm 2 ................. 0.3 low bending strength (0.2-0.4 MPa) and low melting tem- Water content (not ~eater than), % .......... 1.0 perature (1150~ of these plates led to significant metal im- Weight loss upon calcination. % ........... 8 - !5 preg-nation and fusion of the insets, which results in a loss of their thermal-insulation properties. In this connection, the Dinur company developed the pro- During experimental testing of the runner bushes at the Mechel Company, about 800 13-ton ingots of transformer duction for, and the Mechel Company introduced into prac- tice, bushes composed of two layers: sand-cellulose (facing steel were cast using steel feed_heads insulated by single-layer the liquid metal) and kaolin (facing the ingot mold), sand-cellulose inserts and the new double-layer insets. The latter bushes strongly decreased contamination of the stripper I VIZ Joint-Stock'Company, Ekaterinburg, Russia. stage with the sand. The percentage of ingots rejected for ex- 2 Dinur Joint-Stock Company, Pervouralsk, $verdlovsk Region, Russia. cess spalling (at a feedhead cut of 15%) decreased to half the 3 Mechel Joint-Stock Company, Chelyabinsk. Russia. initial level (from 3.3 to 1.53%). 1083-4877/97./3804-0160518.00 ~ 1997 Plenum Publishing Corporatlon
Refractories and Industrial Ceramics – Springer Journals
Published: Nov 26, 2007
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