JPH08143941A - Production of treating agent for molten metal - Google Patents

Abstract

PURPOSE: To produce a molten metal treating agent excellent in reaction yield with the molten metal by coating the surface of the molten metal treating agent with a metal and making the treating agent into small pieces thereby increasing the sp. gr. of the treating agent. CONSTITUTION: At the time of using Mg alloy, Fe-Si alloy, fluor spar, soda ash, carbide, etc., as the treating agent for graphitizing carbon contained in molten state of pig iron, cast iron, cast steel, etc., and spheroidizing the graphite or executing inculant treatment and desulfurizing treatment, these treating agents are filled into a steel pipe or an Ni alloy-made hollow pipe in granular particle state or molten-state, then cooled and solidified. This metallic pipe filled with the treating agent is cut off into the small pieces and added into the molten pig iron, cast iron and cast steel. The treating agent small in sp. gr. is increased in sp. gr. by filling it into the metallic pipe and stayed in the inner part of the molten pig iron, etc., without floating up to the molten slag on the surface of the molten pig iron, etc., and reacted with the molten pig iron, etc., in high yield and acted as the graphitization of contained carbon, the spheroidizing agent of graphite, inoculant and desulfurizing agent.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a molten metal treating agent necessary for producing pig iron, cast iron, cast steel and the like.

[0002]

2. Description of the Related Art In the production of industrially used metals, graphitization treatment, graphite spheroidization treatment, inoculation treatment, desulfurization treatment, etc. of metal are essential, and conventionally, additives such as magnesium and silicon having a low specific gravity are used. Is alloyed with iron or nickel and added to the molten metal in the form of powder or granules, the additive is pressed in by the plunger method or wire method, or the ladle to which the additive is added is capped or the ladle is opened. Facility measures have been adopted to tilt or stir the molten metal in the ladle.

However, since the reaction between the molten metal at a high temperature of about 1700K and the additive is extremely vigorous, the additive is released during its absorption into the molten metal and loses its effectiveness, and white smoke and dust are generated to create a working environment. Makes it significantly worse.

An object of the present invention is to solve the above-mentioned problems found in a molten metal treating agent, and in particular, it is possible to easily improve a treating agent having a non-floating characteristic utilizing the latent heat of fusion of metal by increasing the specific gravity. An object of the present invention is to provide a method for producing a molten metal treatment agent that can be produced.

[0005]

According to the present invention, a molten metal treatment additive is sucked and filled into a hollow body containing iron or nickel as a main component in a granular or molten state by utilizing a reduced pressure, and if desired. It is a method for producing a molten metal treatment agent, which is characterized in that it is cut into small pieces.

As the metal-treating additive used in the method of the present invention, well-known metal-treating additives such as graphitizing treatment, graphite spheroidizing treatment, inoculation treatment, desulfurization treatment and the like in treating the metal in a molten state are used. be able to. Therefore, its kind is not particularly limited, and specific examples thereof include well-known additives such as magnesium alloy, ferrosilicon alloy, fluorite, soda ash, and carbide.

The present invention substantially floats when adding such a metal-treating additive to a molten metal by coating the whole or a substantial part of a solid metal containing iron or nickel as a main component into a small piece. It is possible to produce high-quality products under controlled and stable operations, and to produce a high-quality metal-coated treatment agent in a short time, use a metal hollow body for metal treatment. It is characterized in that the additives for use are suction-filled under reduced pressure.

As the metal hollow body containing iron or nickel as a main component, a metal tube having a small diameter is preferably used. As the metal tube, a round tube having an inner diameter of 1 to 50 mm, preferably 3 to 10 mm is preferably used, but a square tube corresponding to the cross-sectional area of the round tube can also be preferably used. The metal constituting the metal tube is mainly composed of iron or nickel, and particularly preferable tubes are a steel tube and a nickel alloy tube.

As the metal pipe, either a seam pipe having a welded portion in the longitudinal direction or a seamless pipe having no welded portion can be used, but the seam pipe is often preferably used. The reason is that the unevenness of the seam portion in the seam pipe has a function of holding the additive filled in the pipe.

As the hollow body, a shape other than a metal tube may be used as long as it can be suction-filled by decompression.

In the present invention, the additive is suction-filled under reduced pressure into a hollow body typified by the metal tube exemplified above.

The state of the additive at the time of filling is in the molten state or in the form of powder or granules (here, the term “powder or granule” refers to the solid state of conventionally used additives such as powder, granules and lumps). However, the molten state is preferable for more uniform and high-density packing. The reduced pressure suction filling conditions differ depending on the specific gravity of the additive and the like. When a metal tube is used, its length is not particularly limited, but usually about 500 to 2000 mm is preferable. When the molten additive is suction-filled, the lower end of the metal tube is usually immersed in the melting tank while being normally -70 to 650.
When the pressure is reduced to mmHg, the melt is immediately suction-filled into the metal tube. When the suction is held for several seconds after the completion of the filling, the bottom is solidified and the filling is completed. After filling, press and cut to an appropriate size to make small pieces. In this case, if the processing is performed at a warm temperature, the processing becomes easy.

When the powdery or granular additive is to be filled in the metal pipe cold, the lower end of the metal pipe is sucked and filled while being immersed in the additive tank as described above, and both ends are closed during suction to complete the filling. After that, press and cut to an appropriate size.

Examples of additives that can be filled in either a molten state or a granular state are Fe--Si--Mg alloy and Fe.
-Sig alloy, fluorite, etc. Examples of additives that are filled in the form of powder or granules include soda ash and carbide. Pressing and cutting are preferred for breaking the filled metal tube into small pieces, but of course other means may be used. The ends of the small pieces obtained by using the pressing and cutting process can be sealed with the cutting ends of the metal tube. Further, when the melted additive is filled and solidified, the additive is in a solid state and maintains the integrity as a molten metal treating agent without sealing the end portion. Therefore, if there is no particular problem with the deterioration of the additive during storage or the reactivity during use, the end may be cut open.

The size of the piece-like metal treating agent is usually 0.1 to 10.
100 cm ³ approximately, preferably from 1 to 30 cm ³ approximately. When using a metal tube, it is preferable to cut into about 1 to 10 cm in the length direction. The specific gravity (density) of the obtained flaky molten metal treating agent depends on the specific gravity of the additive and the specific gravity of the metal constituting the hollow body, and varies depending on their quantity relationship. In the case of the combination of the same metal pipe and the same additive, as the metal pipe is flattened and the inner cross-sectional area is made non-circular, the ratio of the metal weight to the filling weight per unit length of the metal pipe is increased. Things will come. Therefore, the same metal tube can be used to manufacture molten metal treating agents having different specific gravities. Also, the weight of the pieces can of course be adjusted by adjusting the cutting length. Thus, usually 4.
It is possible to obtain a molten metal treating agent having a volume density in the range of 5 to 8.2 g / cm ³ and having a bulk density capable of substantially suppressing floating in a molten metal and having a constant quality in an extremely short time.

FIG. 1 is a schematic view of producing a molten metal treating agent by depressurizing from above the metal tube using a vacuum pump, suction-filling the molten additive into the metal tube, and then pressing and cutting.

[0017]

【Example】

Example 1 An outer diameter of 17.3 m is provided on the upper part of a 1770 K Fe-Si melting furnace.
m, wall thickness 2.8 mm, length 100 cm was set, and the lower end of the steel pipe was immersed in a melting furnace while depressurizing from above with -450 mmHg. As a result, Fe-Si was filled to the upper part of the steel pipe in 0.5 seconds. When held on the furnace while suctioning for 10 seconds, Fe-Si in the lower part of the steel tube solidified. Fe-Si
The bulk density of the molten metal additive obtained by press-cutting after cooling a 100 cm steel rod filled with No. 1 to about 670 K was 6.6.

8.3 kg of this molten metal treating agent was added to 200 k
It was set in a ladle of g and the molten metal of 1773K was injected to observe the floating of the molten metal treating agent and the thermal behavior during the treatment. From the start of the molten metal until the end of the molten metal 20 seconds later, the molten metal treating agent did not float up, and then the molten metal convection continued for about 25 seconds.
The reaction was mild and white smoke was very small, and it was observed that the additive was uniformly diffused.

Example 2 A steel pipe having an outer diameter of 21.2 mm, a wall thickness of 2.8 mm and a length of 100 cm was inserted into a Fe-Si grain tank of 3 mm or less and depressurized at -450 mmHg from the upper part, and it could be filled in 2 seconds. The bulk density of the molten metal additive obtained by press-cutting after closing both ends of this steel pipe was 5.3. The bulk density of the melt additive manually filled with the same Fe-Si of 3 mm or less by vibration and thrust without depressurization was 4.9, and the filling time also required 5 minutes.

The bulk density of 5.3 did not float above the melt from the start of the melt to the end of the melt, but the bulk density of 4.3.
No. 9 floated above the molten metal.

Example 3 As a molten iron desulfurization additive, a steel pipe similar to that of Example 1 was set on a commercially available soda ash powder, suctioned under reduced pressure from the upper portion, and similarly press cut. This is used as a desulfurization melt processing agent, and 2
It was set in a ladle of 00 kg and then poured. The density of the desulfurization melt processing agent was adjusted to 6.5 g / cm ³ .

C = 3.6%, Si = 2.45%, Mn =
0.54%, P = 0.55%, S = 0.085-0.9
The desulfurization effect was investigated by adding a desulfurization melting treatment agent in an amount capable of desulfurizing all S in the hot metal made of water-cooled, cold-air cupola having a chemical composition of 1%.

Each of the melt treating agents using the desulfurizing melt treating agent of the present invention did not float, the molten metal was continuously stirred, the amount of dust was small, and a high desulfurization efficiency of about 80% was obtained. Further, as a result of treating 200 kg of hot metal at 1753 K with a melt processing agent using carbide, no decrease in molten metal temperature was observed due to an exothermic reaction with the hot metal.

Example 4 Using a stainless steel pipe of JIS G3463, Mg and FeSi for inoculation, the additive was vacuum-suction filled into the stainless steel pipe by the method shown in Example 1 and press cut.
This treatment agent is a coating material of stainless steel instead of iron for the spheroidizing treatment of Ni-resist spheroidal graphite cast iron of high nickel (hereinafter Ni), and since the density of Ni is high, a higher density treatment agent is possible. Becomes The density of this treating agent is as high as 7.4 g / cm ^3, and 3040 g of this molten metal treating agent having a unit weight of 29.5 g (Mg content ratio 1.15%) is 50 k
g of hot water and reacted at 1773K. Floating prevention and molten metal stirring were maintained, and the reaction was mild.

As described above, the method for producing a molten metal treating agent of the present invention has the following characteristics. (1) The density of the molten metal treating agent can be made very close to the density of the molten metal to be treated, and the floating of the molten metal treating agent during treatment can be reliably prevented. For example, the density of the conventional spheroidizing agent of spheroidal graphite cast iron is about 4.5 g / cm ³ , and the density is increased to 6 g / cm ³ or more even if the powder or granular material is pressed and sintered to increase the density. Therefore, it floats in molten iron having a density of about 7.2 g / cm ³ . As a countermeasure, it is necessary to use a cover material and take measures in terms of equipment. (2) In the molten metal treating agent obtained by the method of the present invention, the hollow metal plate covering at the time of treatment takes heat of fusion to lower the ambient temperature, and the hollow metal plates fuse together to help prevent floating. Difficult to surface even at low density. (3) Since the molten metal treating agent obtained by the method of the present invention, after treatment, is sequentially dissolved from the surface layer to cause convection of the molten metal, the inoculation time of the additive is long and the diffusion is uniform. Therefore, the product has a very fine metal structure and the material properties are improved. (4) Since the molten metal treating agent obtained by the method of the present invention coats and protects the additive with a strong hollow metal plate, it can maintain the preservability against damage during transportation, oxidation of the additive, moisture absorption and the like. (5) By using the molten metal treating agent obtained by the method of the present invention, the working environment of white smoke, dust, etc. can be improved, and cleaning management of the ladle becomes easy.

(6) With a simple depressurizing facility, powdery or granular additives can be instantly charged, and the economy and workability are excellent. (7) Since the filling is instantaneous, it is possible to prevent the melted additive from being oxidized. (8) The solidification temperature is about 1470 even if the inner diameter of the metal tube is 3 mm.
The molten additive of K can be instantly filled into the metal tube without any gap. (9) The additive in the form of powder or granules can be uniformly filled. (10) Equipment cost and manufacturing cost are low.

[Brief description of drawings]

FIG. 1 is a schematic view showing an example of the method of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 vacuum pump, 2 suction metal fittings, 3 metal pipe support tool, 4 molten additive, 5 press mold, 6 magnet, 7 molten metal treating agent

Claims (6)

[Claims] 1. A molten metal processing additive is suction-filled into a hollow body containing iron or nickel as a main component in a powdery or granular form by utilizing reduced pressure, and cut into small pieces if desired. And a method for producing a molten metal treating agent. 2. The method according to claim 1, wherein the hollow body is a hollow tube. 3. The method according to claim 1, wherein the hollow tube is a nickel alloy tube or a steel tube. 4. The method according to claim 1, wherein the metal treating agent obtained has a specific gravity such that the metal treating agent added to the molten metal of the treated metal does not substantially float on the surface of the molten metal. 5. A magnesium alloy in which the additive is molten,
The method according to any one of claims 1 to 4, which is a ferrosilicon alloy or fluorite. 6. The method according to claim 1, wherein the additive is a granular magnesium alloy, a ferrosilicon alloy, fluorite, soda ash or carbide.