Accelerated drying of the poured monolithic silica lining of steel teeming ladles under a suspended roof

Abstract

Monolithic refractory linings are finding ever wider use in steel-teeming ladles since they eliminate the use of scarce refractory brick, do not require complex equipment, large capital expenditures, or manual labor, and ease complex mechanization of the process.Since 1972, 130-ton steel teeming ladles with cast monolithic linings have been used in the Open Hearth Shop of Seversk Pipe Plant. Silica refractory concrete consisting of 96-98% crystalline quartzite (TU 14-8-92--74, type ZKM-97), 2-4% ferrochrome slag , and 20-25% (above 100%) waterglass with a density of i.i0 g/cm 3 (GOST 13078--81) is used for preparation of them. The refractory concrete has a moisture content of 18-22% and its averaged poured (volumetric) weight is 2.2 tons/m 3. The method of preparation of the poured lining is describedTo a significant degree the properties and life of the lining are determined by the method of drying of it. A poured monolithic lining is normally dried for 12-30 h depending upon the size of the ladle at temperatures not exceeding 650-700~ [i, 2]. The optimum is assumed to be a temperature of about 500~The drying time for a poured lining is 10-15 times greater than the time for preparation of it. In addition, the fuel consumption in such a drying method is very great and the lining is porous (open porosity 28-30%).As the result, less critical types of steel are teemed from ladles with a new lining, that is, a so-called "washing" of the lining is done. After teeming of the steel the strength of the lining surface layer increases and the open porosity decreases as the result of sintering and formation of a vitrified surface.In the plant, ladles were dried on stands equipped with cantilever rotatable burners with a gas consumption of 450-500 mS/h for 12-14 h. In such a drying method the heat of the exhaust gases is poorly utilized. It is possible to preserve the heat by enclosing the ladles on top or by inverting them with the bottom up in drying [i, 2] but in tilting of the ladle the danger exists of damage to the lining.At Seversk Pipe Plant tests were made on drying of ladles under a special cover with a hole for the burner. The cover was lined with the same compound as the ladle. The use of the cover made it possible to reduce the drying time and gas consumption and increase the life of ladle linings.A project was developed based on the results of tests in collaboration with the All-Union Scientific-Research Institute for ~ Metallurgical Thermal Engineering and equipment was built for drying of steel teeming ladle linings under a suspended roof [3], Investigations were made in collaboration with the Institute