SU564336A1 - Method for conducting smelting - Google Patents

Description

(54) METHOD OF MANAGEMENT OF MELTING

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This invention relates to the field of ferrous metallurgy, in particular to methods of conducting smelting in an electric arc furnace.

The process of preparing steel of a certain brand in an electric arc furnace involves heating, melting the ingot loaded into the furnace and adding the melt to a given composition.

The state of the charge materials contained in the electric furnace fe varies during smelting, the amount of heat required for the metal bath also changes.

The optimum electrical mode for each melting period is selected based on an analysis of the energy balance of the electric furnace, which in a general case depends on the electrical and thermal characteristics of the furnace.

The known method of selecting the rational electric mode of operation of the furnace, in which the power ij is taken as the main quantity. At the beginning of melting, the arc burns open to the loaded mixture, which has a negative effect on

the resistance of the walls and the roof of the furnace, therefore the power input is minimal. As the charge melts, the electrodes descend — into the formed wells, the arcs are closed with solder, their effect on the lining is minimal, and the power input must be maximal. At the end of the melting period, the arcs open, and the power introduced into the furnace decreases.

The known method of conducting melting is

.calculated. However, many issues of the thermal operation of the furnace lining do not lend themselves to theoretical calculation, therefore, only by analytical methods it is not possible to determine a rational electric mode. It is necessary to introduce corrections obtained experimentally.

There is a known method of conducting smelting in a steel-smelting arc furnace, including

Claims (2)

heating, melting the charge, fine-tuning the melt to a given composition and the release of finished steel from the furnace. In order to increase the service life of the lining from the moment the arcs are opened, the transformer is switched to a lower voltage level, which leads to a decrease in the arc length | and to a concurrent decrease in the sheathing intensity of the lining 2. the time of the intake of the charge and the heating of the liquid bath. In addition, the furnace lining, although to a lesser extent, is subject to significant irradiation by arcs. To eliminate these drawbacks and to increase the efficiency of electrotrans with the maxant, the arc of electric power is introduced into the furnace while maintaining Kae-Sini's oval with a waist, and in the presence of distortions of the oval shape in the form of peaks, the supershang “yuk increase, and with the degeneration of the oval, the GOK decreases. Fig; Figure 1 shows the current and voltage signals applied to the oscillograph 1; types of current-voltage characteristics; in fig. 2 - view of the current-voltage characteristics when the arc is burning for a cold mixture | in fig. 3 - the same, with open i arc burning to the melt, in FIG. 4 - the same, when the arc is completely buried in the melt. The schematic drawing of sha in FIG. 1, includes measuring transformers TT and TT, resistances of the shunt and divider, and ft, short CS network, furnace transformer TP, electrode 3, and Isj oscilloscope. According to the proposed method, the smelting leads to XY, for example, in the following way. During melting, an oscilloscope includes vertical and horizontal scanning, the inputs of which are supplied with signals proportional to the current and voltage of the arc according to the scheme shown in FIG. 1, and during the melting process, they observe the character of the wave and shape by changing the arc current. During the burning of electric arcs on a cold mixture during the melting of wells, frequent short circuits have occurred, and the first characteristics (Fig. 2) have an uneven shape. When a puddle of metal appears, the arc burns to the melt, and the current-voltage characteristic has the form shown in FIG. 3 In this case, there is a section of negative differential resistance due to the ionization of the arc gap. A Volga-ampere characteristic of this type indicates that KOLOD1KHY is melted, the formation of a liquid metal bath has occurred, and the arcs begin to open. At this moment, by changing the arc current, the UT is completely buried in the liquid bath, thus reducing the intensity of the lining irradiation to the lowest possible limits. When the arcs are fully buried, the current-voltage characteristics have the form of a Cassini oval with a waist, and the waist can be determined by the formula: () -2c (b о | arcs, C is the focal distance, and -const-, the dynamic characteristic of this kind is maintained until the end of the period of complete melting of the charge and bringing the temperature of the melt to the required one in accordance with the technology.The application of the proposed method will allow the melting of the charge and heating of the liquid metal bath to the optimum ale The critical modes are characterized by the maximum energy given off to the melt and the minimum energy going to the lining, all this leads to an increase in the efficiency of the electric furnace and, consequently, to an increase in its performance due to a reduction in the melt-melting period and melting in general. , reducing the irradiance of the lining to a minimum allows increasing its durability, as a result of which the cost of the steel produced is lowered due to a decrease in the EXCELLENT consumption of the refractory and the labor intensity of it. to prepare The invention method of melting in an electric arc furnace, which includes melting the mixture with closed and open arcs and bringing the melt to a predetermined temperature at a given level of electrical power introduced into the furnace, supported by a change in arc current, with the aim of increasing the efficiency of the electric furnace, from the moment of opening the arcs to the achievement of a given melt temperature, the electric power is introduced into the furnace while maintaining the dynamic current-voltage characteristic in the form of ov la Cassini with a waist, and at, the presence of oval shape distortion as peaks ignition current is increased, and at birth the oval neck ellipse in current is reduced. Sources of information taken into account in the examination :, 1.A. I. Stroganov and others. Arc electric furnaces, M., 1972, p. 167-171. 2.N. V. Okorokov, Arc steel-smelting furnaces, M., 1971, p. 114-129. 77-, -H -t 4ChI./