KR100717244B1 - Melting furnace equipped with gas injection means for impurities elimination - Google Patents

Abstract

The present invention has a gas injection means to remove impurities generated when melting the metal, the gas injection into the furnace body through the gas injection means is carried out through the ceramic filter provided in the lower portion of the furnace more effectively impurities It is related to a melting furnace that can be raised to the surface of the molten metal, and even if the melting furnace is for the alloy, uniform mixing of the alloying components is ensured, so that segregation problems can be solved. .

The melting furnace according to the present invention is a furnace body; A porous ceramic filter provided below the furnace body and having pores having a size smaller than that of the dissolved metal particles; And a gas tank connected to the filter and a gas tank connected to the pipe and storing any one gas selected from the group consisting of N ₂ , He, Ne, Ar, or a combination thereof, and a pump provided in the pipe. It comprises a gas injection means consisting of a gas supply member including.

Melting, furnace body, filter, ceramic, gas, impurities, moisture, removal

Description

MELTING FURNACE EQUIPPED WITH GAS INJECTION MEANS FOR IMPURITIES ELIMINATION

1 and 2 are a schematic front sectional view and a plan view of a melting furnace according to the present invention.

<Description of the symbols for the main parts of the drawings>

F: melting furnace 10: furnace

20: filter 30: gas injection means

31: pipe 33: gas supply member

The present invention is a melting furnace,
In particular, it has a gas injection means to remove impurities generated during metal melting
Regarding the melting furnace using electricity as a heat source and the melting process in a vacuum state ,

More specifically, the gas injection into the furnace body through the gas injection means is carried out through the ceramic filter provided in the lower portion of the furnace so that impurities can be effectively raised to the surface of the molten metal, and the melting furnace is alloyed. If it is to ensure a uniform mixing of the alloying component is to solve the segregation (偏析, segregation) problem can be related to the melting furnace to improve the alloy quality.

The process of melting metal is called melting, and the equipment used at this time is called melting furnace.

The casting process using the melting furnace should be able to dissolve the solid raw material to form the ingredients to remove the impurities, to remove impurities, to flow sufficiently in the mold, and to design the melting furnace to play the above role. Should be

Type of melting furnace

Depending on the heat source of the furnace, there are Cupola and crucible furnaces using solid fuels, crucible furnaces and reflectors using liquid fuels, gas fuel furnaces and electric furnaces (eg Heroult arc furnaces),

As a melting furnace for classification cast iron according to the type of molten metal of cast iron for (e.g., in the molten iron (cupola), an electrically) and cast steel for: there is a (for example, an electric furnace, to Ovens, reflection), as dissolution for non-ferrous castings There is a crucible furnace and an electric furnace.

Conventional technology related to injecting gas into a furnace body to remove impurities from a melting furnace includes Patent Registration No. 0197910 (1999.02.25), `` Method for promoting impurity removal during electrode melting casting. ''

The registered patent increases the contact area between the slag and the molten metal by injecting a gas into the slag layer to remove impurities separated from the molten metal by reaction of the slag layer and the impurities in the molten metal during electrode melting casting. The present invention relates to a method for promoting impurity removal that transfers motility to impurities and moves them over the slag layer.

However, since the registered patent has a structure in which an injection tube is arranged from the top of the furnace to the slag layer to inject gas only into the slag layer, it is difficult to apply it to all furnaces in general.

Particularly, in the case of the melting furnace for the alloy, and also the precious metal alloy, when the gas injection tube is used, a problem arises in which the dissolved metal is buried on the outer surface of the pipe, which may cause a problem that a recovery process of the precious metal needs to be added, thereby decreasing productivity.

The present invention is proposed to solve the problem of gas supply through the gas injection tube and the limitation of the general purpose of the patent registration No. 0197910 that introduces a method of injecting gas to remove impurities during melt casting of metal.

Accordingly, an object of the present invention is to provide a melting furnace using a porous filter that does not pass molten metal and passes gas as a means for gas injection into a furnace, and in particular a vacuum melting furnace that uses electricity as a heat source.

In addition, the present invention uses a neutral or inert gas, in particular, selected from the group consisting of N ₂ , He, Ne, Ar, or a combination thereof, and by adding a small amount of H ₂ gas to remove impurities and segregation (偏析) The aim is to provide a furnace that can increase the efficiency of segregation reduction.

Melting furnace having a gas injection means for removing impurities according to the present invention in order to achieve the above object
Noche;
A porous ceramic filter provided below the furnace body and having pores having a size smaller than that of the dissolved metal particles; And
A pipe connected to the filter, and
A gas tank connected to the pipe and storing any one gas selected from the group consisting of N ₂ , He, Ne, Ar, or a combination thereof, and a gas supply member including a pump provided in the pipe. Injection means
It is made, including.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

1 and 2, the melting furnace (F) according to the present invention is one or two or more (five in the figure) provided in the lower part of the furnace (10) having the inner receiving portion (11) Array) porous ceramic filter 20.

The ceramic filter of the melting furnace according to the present invention can be applied to various melting furnaces, but is particularly suitable for using electricity as a heat source as a vacuum melting furnace for alloys.

One reason for this is to use cokes as a heat source, such as a blast furnace for iron ore or Cupola for cast iron.

Crucible furnace using heavy oil or city gas as fuel

With quick melting using a high speed burner,

In the case of directly heating a furnace such as a reverberatory furnace using heavy oil or coal as a heat source, a gap is formed between the furnace body and the filter, the filter itself is broken, or pores are expanded. This is because there is a risk of pouring molten metal.

However, the method according to the present invention may be applied to a furnace using various heat sources by improving the coupling structure of the furnace body and the filter or improving the material and durability of the filter.

Another reason for using electricity as a heat source in the case of selecting a vacuum melting furnace, which is a furnace for melting metal in a vacuum as the melting furnace of the present invention,

This is because if the electricity is used as a heat source while vacuum dissolving the metal, there is no fear of contaminants from flowing from the surroundings and the gas content in the metal can be lowered.

Known electric furnaces include electric resistance furnaces, induction furnaces, and electric arc furnaces.

First resistive furnace is often in the furnace, the furnace, the degree of the small amount of dissolved per 1㎏ to heat the metal melt by the heat radiation from the heating element surface to the heat generating element such as a metal and a ceramic,

Induction melting furnace is a furnace that heats and dissolves metal by Joule heat by electromagnetic induction action, and the molten metal in the furnace is stirred by electromagnetic force, which makes it possible to produce homogeneous products. Widely used to large roads,

Finally, the arc melting furnace is an arc that generates the arc by contacting the lower end of the electrode and the bottom of the water-cooled crucible, and the arc heat dissolves the electrode. The electrode gradually melts into a water-drop-shaped copper crucible. It falls and degasses at this time, and this furnace is used for metal melting | fusing point with high activity or a melting point, such as titanium and zirconium.

Therefore, the melting furnace of the present invention is used for forming alloys, in particular precious metal alloys,
In addition, when electricity is used as a heat source with low risk of pollution,
It is preferable to comprise an induction melting furnace, more specifically, a high frequency induction furnace in the above known electric furnace.

Meanwhile, the ceramic filter 20 is a porous ceramic filter in which a plurality of pores smaller than the dissolved metal particles and larger than the particles of the gas to be injected are formed.

Since the ceramic filter can withstand a high temperature of 2,000 ° C. or higher and does not corrode in an acidic or basic state, it is preferable to use a ceramic filter mainly composed of mullite (Mullite, 3Al ₂ O ₃ · 2SiO ₂ ) or SiC. ,

Its pore size varies depending on the type of metal and gas, but can be approximately 15-25 nm,

Commercially, it can be made to order by Seowon Tech Co., Ltd. in Incheon, Korea.

The furnace body 10 is provided with a mounting portion 13a for the filter 20, and a connection nozzle of a pipe 31 for supplying gas to the accommodation portion 11 of the furnace body 10 through the filter. A mounting portion 13b for 31b is also formed under the mounting portion for the filter.

The pipe 31 is provided with a valve 31a that is opened or closed manually or automatically,

The gas injection means 30 including the pipe further includes a gas supply member 33 including a gas tank 33 and a pump 33b connected to the pipe.

Since the pressing force of the pump 33b is sufficient to allow gas to pass through the filter 20, it may be omitted in some cases.

The gas stored in the tank 33a of the gas supply member 33 may be neutral (N ₂ ) or inert gas selected from the group consisting of N ₂ , He, Ne, Ar, or a combination thereof.

The supplied gas further contains a small amount (about 0.1 to 5% by volume) of H ₂ gas, so that the alloy component mixing efficiency and temperature increase can be obtained by stirring by burning hydrogen gas. The content of the hydrogen gas in the gas is caution because there is a risk of explosion if excessive.

Introduction of the gas injection means in the present invention is to improve the quality of the casting, and finally the molded product by removing impurities, various gases, and water, in the present specification, the term "removal of impurities" is unwanted gas and water It is a broad concept that includes elimination.

As the gas introduced through the ceramic filter 20 rises due to buoyancy (hydrogen gas burns), impurities move to the surface of the molten metal and promote mixing of alloying components.

Impurities transferred to the melt surface can be removed manually or by automated equipment to obtain the desired purity and uniform content of the alloy during casting and tapping.

In addition, the introduction of the filter 20 and the gas injection means 30 arranged in the furnace 10 in the melting furnace according to the present invention was confirmed that the segregation phenomenon occurring in the alloying process can also be solved.
Segregation is a phenomenon in which the composition of the first precipitated part and the later solidified part when the molten alloy solidifies is different.

In other words, when making an alloy, all the component metals are dissolved in a liquid state and then solidified. In this case, the first solidified portion and the later solidified portion are generally different in composition, resulting in nonuniformity in the alloy composition. The extent varies greatly depending on the type of alloy and the solidification conditions.

In large materials, sometimes macro segregation is prominent so that the surface and the center can be distinguished by the naked eye. When microcrystals of individual crystals in the material are observed under a microscope, micro segregation can be seen as a difference in composition between the center and the periphery of the crystal.

Conventionally, the prevention of coagulation segregation has been used for the homogenization immersion method which reduces the interdiffusion of atoms when heated to a suitable temperature for a long time.

In addition to coagulation segregation, special segregation, called grain boundary segregation, occurs. This is a phenomenon in which impurity atoms gather at the boundary of crystal grains and is caused by atoms not being arranged in an orderly manner at the boundary. As grain boundary segregation, metallic materials are sometimes destroyed at the boundary of crystal grains.

The grain boundary segregation is not alleviated even by using the homogenizing immersion method, but rather, impurities may be further collected.

The inventors of the present invention constituted a melting furnace according to the present invention and conducted various alloy tests for precious metal alloys such as gold and silver, and confirmed that both kinds of segregation were prevented.

It has been found to be able to produce good products even in casting and tapping after rolling and pulling.

The capacity of the furnace body 10 for the noble metal alloy is generally about 7 to 15 kg, and the melting temperature should be 1,700 ° C. or more,

The gas supplied from the gas supply member 33 is injected into the furnace body for about 2 to 5 minutes before the metal component is completely dissolved and then cast, and passes through a 3 to 7 minute rest period.

As shown in the lower portion of the furnace 10, the plurality of filters 20 for supplying the gas are preferably arranged to enable rotational stirring of the molten metal by a gas which is elevated by buoyancy.

This is because in the conventional vacuum electric furnace heating method through the medium frequency or high frequency, as the molten metal is rotated in one direction as if it is a dehydrator, vortices are generated and impurities cannot be exposed to the surface, and alloy components are also not smoothly and uniformly mixed. This is because by arranging a plurality of filters, it is possible to solve the problem of segregation phenomenon more reliably by preventing vortex rotation and forming turbulent flow.

As described above, the melting furnace having a gas injection means for removing impurities according to the present invention is a means for gas injection into a furnace body, and a melting furnace using a porous filter that does not pass molten metal and allows gas to pass through. Providing a vacuum furnace using electricity as a heat source, and using a gas selected from the group consisting of neutral or inert gas, in particular N ₂ , He, Ne, Ar, or a combination thereof, and a trace amount of H ₂ gas Addition can increase the efficiency of removing impurities and reducing segregation phenomenon.

In the above description, although the conventionally known techniques related to melting furnaces, in particular vacuum electric melting furnaces, are omitted, those skilled in the art will naturally be able to infer and deduce this.

In addition, in the above description of the present invention with reference to the accompanying drawings with reference to the accompanying drawings, the melting furnace having a specific shape and structure, but the present invention can be variously modified and changed by those skilled in the art, such modifications and changes are the scope of protection of the present invention Should be interpreted as belonging to.

Claims (7)

delete Noche; A porous ceramic filter provided below the furnace body and having pores having a size smaller than that of the dissolved metal particles; And A pipe connected to the filter, and A gas tank connected to the pipe and storing any one gas selected from the group consisting of N ₂ , He, Ne, Ar, or a combination thereof, and a gas supply member including a pump provided in the pipe. Injection means Melting furnace consisting of. The method of claim 2, Melting furnace, characterized in that the gas stored in the gas tank further comprises a trace amount of H ₂ gas. The method of claim 2 or 3, Melting furnace characterized in that the filter is provided with two or more in the lower portion of the furnace body. delete The method of claim 2 or 3, The melting furnace is for the alloy, The heat source is an electric furnace, characterized in that the electricity. The method of claim 6, Melting furnace, characterized in that the melting furnace is a vacuum melting furnace.

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