In the Converter Shop of Azov Steel Combine periclase-lime refractories previously heat treated using a special cycle are used for fining the working layer of the walls of steel teeming ladles. In this shop the method of ladle treatment of steel includes desulfurization of the metal in ladles by treatment with liquid slag synthetic or solid slag-forming mixtures and in some cases with both simultaneously.The liquid synthetic has a composition of (%)* 4045 CaO, 35-40 A1203, <5 SiO2, 4-6 TiO2, and < 1 iron oxides. The temperature of the liquid synthetic slag during pouring into the ladle is 1680-1720~ (superheated, that is, 160-200~ over the liquidus temperature).Lime and fluorespar in a 4:1 ratio are used as the solid slag-forming mixture. Freshly fired lime containing not less than 92% CaO + MgO and fluorspar containing not more than 10% SiO 2 are used. The grain size composition of the solid slag-forming mixture is 40-50% 15-30 mm fraction, 30-35% 5-15 mm fraction, and _<30% finer than 5 ram.The liquid synthetic slag is poured into the steel teeming ladle immediately before tapping of the metal from the converter into it. The weight of metal in the ladle is 340-360 tons. The specific consumption of liquid synthetic slag is 10-20 kg/ton of steel treated (3.44.0 tons/heat). The time of the liquid synthetic slag in the ladle before tapping of metal from the converter is 10-20 min and the metal is in the ladle for 1.5-2.5 h from the start of tapping of it from the converter to the end of teeming of it. Recently for the purpose of economy in scarce and expensive liquid synthetic slag and electric power for production of it a portion or all of the liquid synthetic slag has been replaced by solid slag-forming mixtures.The results of investigations and operating experience showed that in degree of desulfurization the use of 1 kg of solid slag-forming mixture per ton of steel on the average is equivalent to the use of 4 kg of liquid synthetic slag per ton of steel with a basic lining of the ladle. The solid slag-forming mixture is placed in the steel teeming ladle at the time of tapping of the steel from the converter directly under the stream of metal, which significantly accelerates melting of the solid slagforming mixture and desulfurization.The method of ladle treatment of steel includes holding back of the melting slag in turning down of the converter by covering the tap hole with a plug.The steel is deoxidized in the ladle. A portion of the aluminum is added at the start of tapping of the metal from the converter. Upon reaching 1/3-1/2 of the height of filling of the ladle the solid slag-forming mixture is added with subsequent addition of ferroalloys and the remainder of the aluminum. In treatment of steel only with the solid slag-forming mixture the slag formed from the mixture contains 50-60% CaO, 7-13% SiO 2, 20-28% A1203, 1.0-2.0% FeO, 0-1.0% MnO, 0.01-0.08% P205, and 0.2-0.9% S at the end of ladle treatment.The metal is deoxidized in the ladle in tapping based on calculation of obtaining a silicon content at ...

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We studied the sublimation process of the volatile matter of a resin during the course of heating under laboratory conditions and its effect on the qualitative characteristics of the resin-bonded refractories. An uncompacted periciase--lime body mixed with the resin and cubic refractory specimens having an edge of I00 mm that were compacted at i00 N/mm ~ using the same body were studied. Their composition (wt. %) was as follows: magnesite powder (the minus 0.088 mm fraction 66%) 35, dolomite 60, pitch 5, and resin 6 (above 100%). The granulometric composition of the introduced dolomite was as follows: the minus i mm fraction 18.4%, 1-3 mm fraction 80.1%, and the plus 3 mm fraction 1.5%; the apparent density of the body and the specimens was i.72 and 2.91 g/cm ~, respectively; and the ultimate compressive strength of the specimens was found to be 3.72 N/mm 2.In order to prepare the specimens, we used coal tar supplied by the Donetsk KKhZ plant . It has a density of 1.246 g/cm ~ at 20~ a coking value of 50%, and a viscosity C~ = 81 sec.In the first series of experiments, a specimen and the uncompacted body were placed in a furnace and were held at 150~ they were weighed at intervals of i h. The weight loss (liberation of the volatile matter) was expressed as percentage of the weight of the resin. After a significant decrease in the rate of liberation of the volatile matter (after attaining virtually no change in the weight of the refractories), the specimen and the uncompacted body were held in the furnace at successively higher temperatures: 175, 200, 225, 250, 275, 300, 325, and 350~ Figure i shows the effect of the duration of holding of the refractories at a given temperature on the liberation (yield) of the fractions of the resin. An analysis of curves 1 and 2 indicates that at any given temperature, rapid liberation of certain fractions of the volatile matter of the resin occurs during the first 1-2 h of holding; from 2 up to 25 h (depending on the temperature), one observes a uniform decrease in the rate of liberation of the volatile matter followed by virtually complete cessation of this process. Mariupoi'sk institute of Metallurgy. Azovsta!' Complex.