JPH06346162A - Method for melting scrap metal and device therefor - Google Patents

Abstract

PURPOSE:To produce a highly cleaned molten metal by providing plural filters having a different pore diameter, a filtration chamber having a partition wall and an inert gas injection means in a scrap melting furnace. CONSTITUTION:Plural filters 6, 52, 53 and 54 having mutually different average pore diameter are arranged toward the downstream side in order of decreasing mesh, and hence the service life of the filters is prolonged. A partition wall is provided to form a filtration chamber on the downstream side of a scrap inserting and and melting chamber, and inert gas injection means 12 and 13 are furnished to the bottom and/or side wall of the chamber to degass the chamber or to remove an oxide film. Consequently, when the bubbles of the inert gas are floated up, gaseous hydrogen, etc., and oxide film in the melt are entrained by the bubbles to the melt surface, and the melt is agitated to remove the gaseous hydrogen, etc. The finer oxide film and inclusion are then removed by the filters.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a scrap remelting apparatus for obtaining a clean molten metal, particularly an aluminum alloy or a non-ferrous molten metal, from scrap.

[0002]

2. Description of the Related Art Japanese Unexamined Patent Publication (Kokai) No. 1-132724 has been disclosed as a technique for recycling scraps of aluminum alloys or non-ferrous metal materials (for example, Dalai powder and chips). The technology for melting and regenerating these chips is to dissolve the chips continuously and efficiently in the molten metal to enhance the regenerating ability.

However, in recent years, in order to improve the characteristics of aluminum alloy castings, various elements such as Sr and Sb are added to improve the Si phase forming a eutectic.
In many cases, these aluminum alloy castings are painted, and the surface treatment and chemical conversion treatment are performed in that process.
Oxides such as Sb and Mg, P ₂ O ₅ , and TiO ₂ adhere to the surface of the aluminum alloy casting. When these oxides are present in the metal scrap, the oxides are largely dispersed in the molten metal after melting, which lowers the cleanliness of the molten metal.

When the chips generated during machining are melted, the surface area of the chips is larger than that of ordinary scrap materials, so that a large amount of oxide film is generated in addition to the above oxides.

Oxides adhering to the surface of aluminum alloy castings cannot be removed by general molten metal treatment such as flux treatment after melting, and since these oxides coexist with the components in the flux, compounds with a low melting point, That is, it has been found that when complex oxides are formed and these complex oxides are in the molten metal, the mechanical properties of the product are deteriorated. Further, the specific gravity of these complex oxides is heavier than the specific gravity of the aluminum alloy melt, and is easily deposited in the lower part of the melting furnace, and the deposited complex oxide may be dispersed in the melt again by, for example, flux treatment or degassing treatment. Do you get it. Therefore, it has become necessary to remove inclusions such as the complex oxide.

Further, the molten metal having a large amount of the oxide film easily absorbs hydrogen gas, and the molten metal having a small amount of the oxide film is 1.2 to 1.5.
Since it has twice as much hydrogen gas, it is necessary to perform degassing for a longer time, which causes a decrease in molten metal discharge capacity and an increase in degassing cost.

A technique for degassing and removing inclusions in a molten metal holding furnace is disclosed in JP-A-5-8024. In this known example, a molten metal filtration filter is arranged horizontally between the partition wall and the furnace wall on the injection side in the molten metal holding furnace, and a gas injection filter is provided below the partition wall and on the injection side rather than the partition wall. The gas supply pipe is arranged so that the spout of the gas supply pipe can be seen through the jet filter, and the gas removal and the inclusion removal are attempted at the same time.

[0008]

However, it has been found that the following problems occur when the above-mentioned known example is used for a metal scrap molten metal containing a large amount of both oxide film and inclusions. That is, when the inclusions attached to the filtration filter have a large size, the inert gas is less likely to pass through the filtration filter, and the degassing ability of the molten metal before filtration is reduced. In addition, if the filter has a coarse mesh, the ability to remove fine inclusions decreases. Conversely, if a filter with a fine mesh is used, the ability to remove inclusions increases. There is also a drawback that the pores are blocked and the life of the filter for filtration is shortened.

The present invention has been made in view of the above problems, and removes the inclusions and the oxide film, which are problematic when mixed with metal scrap when they are regenerated, and at the same time degasses them. It is an object of the present invention to provide a melting apparatus and a melting method for producing a molten metal having excellent cleanliness.

[0010]

The above-mentioned object is defined in claim 1.
The first invention described in 1), namely, a melting furnace divided into one or a plurality (in the present specification, "melting furnace" means a holding furnace for melting and holding a metal or a melting furnace having a heating means. In the melting apparatus for melting and regenerating the metal scrap in the molten metal by providing a scrap melting furnace for melting at least one or more metal scraps in the scrap melting furnace. A plurality of different filtration filters are provided, and a plurality of partition walls are arranged so as to have a plurality of filtration chambers substantially downstream of the plurality of scrap insertion / melting chambers. And / or a side wall portion is provided with an inert gas jetting means for degassing and / or oxide film removal, which is achieved by a metal scrap melting apparatus.

In a preferred embodiment of the first aspect of the present invention, as described in claim 2, the filter for filtration comprises two or more kinds of filters having different average pore diameters, and the filter has coarse mesh from upstream to downstream. By arranging from the fine filter to the fine filter, the oxide film and the inclusions are removed in order from the large one to the fine one.
It is intended to improve the life of the filter.

In another preferred embodiment of the first invention, as described in claim 3, an inert gas jetting means is provided near the fine filter.

In another preferred embodiment of the first invention, as described in claim 4, the average pore size of the filter for filtration is 1 to 5 m for the first filter for filtration.
m and the final filter is 0.3 to 1.0 mm, the removal efficiency is also high.

As the filter, a ceramic foam filter, a tube type filter, a glass wool or the like having various forms and materials are generally widely used, and any of them can be used as the filter of the present invention. I do not care.

In another preferred embodiment of the first aspect of the present invention, as described in claim 5, in the scrap insertion / melting chamber divided into the plurality of pieces, a raw water melting chamber and a scrap melting chamber are provided. If at least one melting furnace and / or a melting furnace and / or a connecting means for the former melting room and / or the former melting room and / or the scrap melting room are provided, the casting machine holding furnace If further degassing treatment is required before hot water distribution, a small amount of inert gas blowing degassing means may be provided.

When the molten metal is transferred through the connecting means, a heating means is provided to prevent the temperature of the molten metal from lowering, the surface of the molten metal is covered with an inert gas in the case of an easily oxidizable alloy, or the communicating portion is exposed to the atmosphere. You may make it a structure that does not touch.

Further, the above object is to provide a second invention according to claim 6, that is, to provide a scrap melting furnace for melting at least one metal scrap with respect to one or a plurality of melting furnaces. In the melting method of melting and regenerating metal scrap by means of melting, the metal scrap is melted in the scrap insertion / melting chamber provided in the scrap melting furnace, and after degassing and deinclusion treatment with an inert gas, the average pore diameter is The method for melting metal scrap is characterized in that the molten metal is sequentially passed through a plurality of filtration chambers provided with a plurality of different filtration filters to filter out large oxide film and inclusions.

[0018]

Function: The molten metal is degassed and the oxide film is removed by the bubbles of the inert gas generated from the inert gas jetting means. That is, bubbles of inert gas float from the bottom of the molten metal toward the surface of the molten metal, but at that time, carry the hydrogen gas contained in the molten metal and the oxide film to the surface of the molten metal, or stir the molten metal. And remove hydrogen gas.

After that, a finer oxide film and inclusions are removed by a filter for filtration. First, by arranging from a coarse filter to a fine filter from upstream to downstream of the molten metal flow, A relatively large oxide film and inclusions are removed, and then a finer oxide film and inclusions are sequentially removed.

[0020]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a sectional plan view of the first embodiment.
FIG. 3 is a sectional front view of Example 1. A heating burner 10 is provided on the side wall of the source hot water melting chamber 1. The cutting powder melting chamber 7 is connected to the hot water melting chamber 1 by a communication portion 31, and the hot water flows into the cutting powder melting chamber 7 through the communication portion 31. Chip melting chamber 7
A chip introduction chute 2 is provided in the upper part of, and the heat-treated chips are added to the molten metal in the chip melting chamber 7 from above. The added cutting chips are immersed in the molten metal by the rotary blades 8 to accelerate the melting of the cutting chips.

The inert gas is ejected from the bottom through the inert gas introducing pipe 12 through the inert gas outlet 13 as fine bubbles 16 to degas the molten metal in which the chips are melted. In the first embodiment, the inert gas blowout port 13 has a continuous rectangular shape that traverses the chip melting chamber 7, but a plurality of inert gas blowout ports 13 cross the chip dissolving chamber 7. It is possible to arrange them in a straight line with a space therebetween, or to arrange them in a staggered manner. At this time, the oxide film in the molten metal agglomerates on the surface 9 or the side wall of the molten metal, and the oxide film in the molten metal can be reduced, and
The degassing efficiency can be improved. The upper portion 11 of the partition plate is so impermeable that the oxide film condensed on the surface of the molten metal or on the side wall does not enter the filtration chamber.
The molten metal passes through the filter 6 at the bottom of the partition plate, and the second filter 52, 53, 54 (in this embodiment, a tube filter) fixed to the pair of filter fixing plates 4. It is returned to the original hot water melting chamber 1 through the communicating portions 32, 33, 34 provided in the lower part of the partition wall with the original hot water melting chamber, and tapped. As the filter, a ceramic foam filter, a tube type filter, or a glass wool having various forms and materials are generally widely used, but any filter may be used as the filter of the present invention. The average pore diameter of the second filtration filters 52, 53, 54 used at this time was 0.5 mm, but the amount of hot water discharged from the communicating portions 32, 33, 34 was sufficient, and this dissolution before the filter was installed. It was almost the same as the amount of hot water discharged from the furnace. In addition, the tube filters 52, 53, 54 are about 25
The lowest part of the communication part 31 is provided at a position higher than 0 mm and the molten metal surface 9 is attached to the tube filters 52, 53, 54.
If the height was maintained at 250 mm or more from the uppermost part, the molten metal could easily pass through the filter.

A sectional front view of the second embodiment is shown in FIG. In this embodiment, the chip melting chamber 7, the hot water melting chamber 1, the communicating portions 31, 3
Although 2, 33, and 34 have the same arrangement as that of the first embodiment, the structure of the filtration chamber for cleaning the molten metal is as follows. That is, the inert gas introducing pipe 14 and the inert gas blowout port 15 are provided at the corner where the bottom portion and the side wall portion intersect in the filtration chamber in which the second filtration filters 52, 53, 54 are installed, and the molten metal in the filtration chamber is provided. Degassing is possible, and the communication parts 32, 3
It is intended to further reduce the amount of hydrogen gas in the molten metal discharged from Nos. 3 and 34.

The inert gas outlet 15 can be installed below the second filter or on the side wall of the filtration chamber. However, if the inert gas is blown out, the oxide film is secondly formed.
When it adheres to the filtration filters 52, 53, 54 of the above and accelerates clogging, the second filtration filter 52,
The inert gas outlet 15 may be provided at a position where the ejected inert gas does not come into contact with 53 and 54.

FIG. 4 shows a sectional front view of the third embodiment. In this embodiment, the chip melting chamber 7, the hot water melting chamber 1, the communicating portions 31, 3
2, 33 and 34 have the same arrangements as those of the first and second embodiments, but like the second embodiment, the inert gas introducing pipe 14 and the inert gas blowout port 15 are also provided in the filtration chamber. , The active gas outlet 15 to the second filtration filters 53 and 5
4 is different in that it is arranged above the second filtration filters 53 and 54.

In the fourth embodiment shown in FIG. 5, the melting furnaces 21 and 22 and the holding furnace 26 connected to the gutter are provided, and the melting furnace 22 is used as a scrap melting furnace. The active gas ejection means 30, the filter for filtration and its fixing plate 23, the second filter for filtration 24 and its fixing plate 25 were provided. Further, the scrap melting furnace 22 and the holding furnace 26 are provided with tap holes 37 and 38, respectively, and a communicating portion 35 for communicating between the scrap melting furnace 22 and the holding furnace 26 is provided, and the inside of the communicating portion 35 is not in contact with the atmosphere. The structure is such that heating means for keeping heat and heating are provided so that the scrap melting furnace 22 and the holding furnace 26 can freely discharge hot water. A filter 27 is placed in front of the tap 38 of the holding furnace 26.
Is attached. Furthermore, an inert gas blowing rotary degassing device 40 is provided.

AC4CH alloy molten metal (Si; 7%, Mg; 0.35) manufactured by the melting apparatus and the melting method of the present invention.
%, Sr; 100 ppm, and chemical composition alloy with unavoidable impurity components) and AC4B alloy (Si4 ~
8%, Cu 2-4%, and alloy composition of chemical composition having other unavoidable impurity components) were cast into mold test pieces, subjected to T6 treatment, machined, and subjected to tensile test and Charpy impact test. As shown in Fig. 1, it was found that the Charpy impact value was improved by about 20 to 50% by stretching.

[0028]

[Table 1]

Further, the life of the filter for filtration in the conventional method was conventionally 1 to 2 months, but it becomes 2 to 4 months or more in the dissolving apparatus and the dissolving method of the present invention, and the life is extended more than twice. I also understood.

[0030]

As described above, according to the present invention, a large amount of oxide film and inclusions generated when a metal scrap is conventionally melted are removed, and at the same time, the molten gas in the molten metal, which is a metal scrap melting material, is removed. Can be reduced.

Therefore, a high-quality molten metal having a low melting gas and a low inclusion level can be efficiently and easily produced from a metal scrap material having a relatively low cost, so that a strength component which cannot be conventionally used as a metal scrap and important safety It has become possible to manufacture low cost parts such as parts that require high quality. That is, since the oxide film, inclusions, and hydrogen gas when the scrap material is melted are efficiently removed by the present invention, and the life of the filter for filtration is improved, the molten metal that is comparable to the new material molten metal can be obtained. Manufactured at low cost, high strength, high toughness alloys can be easily recycled. Therefore, high quality aluminum alloy castings can be produced from inexpensive scrap materials.

Further, as another effect of the present invention, since the inert gas is ejected while performing the filtration with the filter, the oxide film in the molten metal is efficiently floated on the surface of the molten metal,
The oxide film filtered by the filter for filtration is reduced. As a result, as described above, the service life of the filter for filtration is more than double that of the conventional one, and maintenance of the filter for filtration,
The replacement work can be greatly reduced, and the cost can be reduced.

[Brief description of drawings]

FIG. 1 is a sectional plan view showing a first embodiment of the present invention.

FIG. 2 is a sectional front view showing the first embodiment of the present invention.

FIG. 3 is a sectional front view showing a second embodiment of the present invention.

FIG. 4 is a sectional front view showing a third embodiment of the present invention.

FIG. 5 is a sectional plan view showing a fourth embodiment of the present invention.

[Explanation of symbols]

 1 Motoyu Melting Chamber 2 Chip Introducing Chute 4 Filter Fixing Plate 52 Second Filtration Filter 53 Second Filtration Filter 54 Second Filtration Filter 6 Filtration Filter 7 Chip Dissolving Chamber 8 Rotating Blade 9 Molten Metal Surface 10 Heating Burner 11 Upper Part of Partition Plate 12 Inert Gas Inlet Pipe 13 Inert Gas Outlet Port 14 Inert Gas Inlet Pipe 15 Inert Gas Outlet Port 16 Bubbles 17 Bubbles 21 Melting Furnace 22 Melting Furnace 23 Filtration Filter and Its Fixing Plate 24 Second Filter for Filter 25 Fixing Plate 26 Holding Furnace 27 Filter 28 Filtration Chamber 29 Inert Gas Introducing Tube 30 Inert Gas Injecting Means 31 Communication Portion 32 Communication Portion 33 Communication Portion 34 Communication Portion 35 Communication Portion 36 Communication Portion 37 Ejection Yukou 38 Hot water spout 40 Inert gas blowing rotary degassing device reference number SO93X02 chemistry A written statement that describes the formula, etc.

[Table 1]

Claims (6)

[Claims] 1. A metal scrap melting apparatus for melting and regenerating metal scrap by providing a scrap melting furnace for melting at least one metal scrap in one or a plurality of melting furnaces, wherein the scrap melting furnace A plurality of filtration filters with different average pore diameters are installed inside, and a plurality of partition walls are arranged so that a plurality of filtration chambers are provided downstream of the plurality of scrap insertion / melting chambers. A device for melting metal scrap, characterized in that an inert gas ejection means for degassing and / or oxide film removal is provided on the bottom and / or side wall of the melting chamber. 2. The filter according to claim 1, wherein the filter for filtration is composed of two or more kinds of filters having different average pore diameters, and arranged from a filter having coarse mesh to a filter having fine mesh from upstream to downstream. Melting equipment for metal scrap. 3. The apparatus for melting metal scrap according to claim 1, wherein an inert gas jetting means is provided near the fine mesh filter. 4. The average pore size of the filtration filter is first
The apparatus for dissolving metal scrap according to any one of claims 1 to 3, wherein the filter for filtration is 1 to 5 mm and the final filter is 0.3 to 1.0 mm. 5. At least one original hot water melting chamber and at least one scrap melting room and / or melting furnace are installed in the scrap inserting / melting room divided into the plurality of pieces, and the original hot water melting room and / or The apparatus for melting metal scrap according to any one of claims 1 to 4, further comprising a connecting means for connecting the former molten metal chamber and the scrap melting chamber and / or the scrap melting furnace. 6. A method of melting a metal scrap, wherein a scrap melting furnace for melting at least one metal scrap is provided in one or a plurality of melting furnaces to melt and regenerate the metal scrap, wherein the scrap melting furnace After the metal scrap is melted in the scrap insertion / melting chamber provided inside and degassed and deinclusions removed by an inert gas, a plurality of filtration filters with different average pore diameters are provided. A method for melting metal scrap, characterized in that a large oxide film and inclusions are filtered by sequentially passing the molten metal through a filtration chamber.