SU950778A1 - Method for introducing additives to molten metal - Google Patents

Description

This invention relates to ferrous metallurgy, in particular to the introduction of deoxidizing agents or alloying additives into molten steel.

The known method of introducing aluminum for deoxidation and alloying into molten steel consists in feeding aluminum wire with a diameter of more than 5 mm at a speed of more than 5 m / s through a layer of slag. Equipment for introducing aluminum consists of a drum with aluminum wire wound on it, a feed mechanism and a guide mechanism Cl.

The disadvantages of this method are the low absorption of aluminum and its uneven distribution in the bulk of the metal.

The closest in technical essence to the present invention is a method of introducing components into a liquid metal, consisting in introducing additives in the form of a wire or a flexible rod, which are plated in an organic coating, such as rubber, and introduced into a metal bath at a rate of 0.1-15. 0 m / s The organic compound decomposes to form gases that bubble the bath, improving the absorption of the added elements. polytetrafluoroethylene or polymonochlorotrifluoroethylene are used as organics. The wire from the drum enters the tape mechanism and is fed to the metal 2 through a guide tube.

The disadvantage of this method is that the organic coating evaporates before the melt is melted,

10, whereby mainly the melt is bubbled above the melting zone of the additives. And the melted particles of the additive contact mainly with the liquid metal matrix,

15 gas that was not sparged, which does not lead to a significant increase in the absorption of additives and the uniform distribution of aluminum.

20

The aim of the invention is a more complete absorption, uniform distribution (division of additives and improvement of the quality of the metal.

The goal is achieved by

25 that, in the known method of introducing additives into the liquid metal while simultaneously sparging the melt with gases, the additives are introduced in the form of a continuously supplied tube through which an inert gas is simultaneously fed. Moreover, fine modifying or alloying additives are additionally supplied through the tube to the inert gas stream. The addition of additives in the form of a tube through which an inert gas flows in contributes to the formation of a metallic crust at the initial moment on the tube due to cooling, with gas, which prevents the additive from premature contact with the melt. As a result, the additive penetrates into the melt to a considerable depth, where the melting of the metal shell ends, which is also facilitated by a higher rigidity of the tube in comparison with a bar of the equivalent cross section. The conditions for mixing the melt are improved and the assimilation of the additives is increased, since the melted particles envelop the exit of the inert gas from the tube with bubbles and then contact with the volumes of the melt which interact with the inert gas. FIG. 1 shows the scheme of tube and gas supply to the melt; in fig. 2, node I in FIG. 1 (tube connection with gas supply). The method is carried out as follows. Tube 1 is supplied wound on drum 2 with a hollow axis 3. One end of the hollow axis 3 is plugged, and the second end is connected to rotating 4, and argon is supplied through the quote. The lower end of the tube 1 (internal coil) is connected to the hollow axis 3 by means of a length of hose 5 and a choke (Fig. 2). When opening the valve 7, argon through the coupling 4, the hollow axis 3 and the nozzle b enters the tube 1. It is necessary to make sure that the argon leaves the outer end of the tube 1. Then this end of the tube 1 is set into the feed rollers 8 driven by the drive 9 The feed rollers 8 have semicircular or semi-oval grooves on the surface, which ensures a good grip of the tube and minimizes its deformation. After the feeding rollers 8, the tube 1 enters the guide wiring 1 and then into the tank 11 with the metallic melt. The tube is fed into the melt at a constant rate. and the flow rate of the additive is controlled by varying the duration of the supply using a time relay. The argon pressure at the inlet to the tube is set taking into account the friction head loss, as the tube length decreases during its supply, the argon pressure is gradually reduced by the calculated value. After stopping the supply of the tube to the melt, the supply of argon is also stopped by closing the fan 7. Example 1. In a bucket with a capacity of 350 tons of steel, enter the aluminum tube in an amount of 2 kg / t and simultaneously purge with argon. The tube with a diameter of 20/16 mm. Duration of input is 10 minutes. The calculation shows that 700 kg of an aluminum tube with a diameter of 20/16 mm has a length of 2290 m. The input speed is 3.8 m / s. When the tube is 3 m deep to overcome the hydrostatic pressure of the metal melt column, the argon pressure at the tube exit must be at least 0.21 MPa. The pressure loss in the tube is 0.6 MPa. Therefore, at the beginning of the filing, the argon pressure at the tube inlet must be at least 0.81 MPa, for example, 0.85 MPa. As the aluminum tube is fed into the melt, the argon pressure must be gradually reduced to 0.25 MPa. When feeding a thick-walled tube, its length and feed rate are shorter. Example 2. A bucket with a capacity of 350 tons is poured in a continuous way into two strands into a mold with a section of 250X1600 mm. During casting, an aluminum tube with a diameter of 20/16 mm in an amount of 0.5 kg / ton should be introduced into the mold. At the stream, the tube consumption is 87.5 kg or 288 m. The tube feed rate into the mold should be 3.2 m / min or 54 mm / s. The head loss in the tube is 0.08 MPa. The pressure of the melt column at a depth of 1 m (assumed depth of the tube) is 0.07 MPa. Therefore, the initial pressure of argon at the inlet to the tube should be about 0.2 MPa, and by the end of casting it should be gradually reduced to 0.12 MPa. If there is more than 87.5 kg of aluminum tube in the coil, the pressure of argon must be increased accordingly. If necessary, powdered modifying or alloying additives, for example, REM, Zr, B, Nb, Mg.Ca, etc. can also be supplied through a tube in an argon flow. This can be done by installing between the valve 7 and the rotating coupling 4 of the ejector connected to powder. The argon supplied through the aluminum tube cools it and promotes the formation of a metallic crust on the tube, which protects the aluminum from premature contact with the steel melt and contributes to a greater penetration of the aluminum into the melt. Higher tube deepening is also due to its higher rigidity compared with a bar of equivalent cross section. The steel shell on the aluminum tube can be maintained until it is melted and overheated.

Claims (2)

Claim 1. The method of introducing additives into a liquid metal with simultaneous bubbling of the melt by gases, characterized in that, in order to more 15 of complete assimilation, uniform distribution of additives and improving the quality of the metal, additives are introduced in the form of a continuously supplied tube through which 2θ inert gas is simultaneously supplied. 2. The method of pop. 1, characterized in that through the tube in a stream of inert gas, additionally fine-dispersed modifying or alloying additives are additionally supplied.