Metal Melting Furnace

Abstract

The present invention provides a molten metal furnace that can prevent or suppress molten metal leakage and can control the leakage direction. In a molten metal furnace having an outer wall (1) on the outer peripheral portion and having a molten metal storage portion for holding molten metal (M), two or more layers of lining material layers are provided on the inner wall of the molten metal furnace forming the molten metal storage portion. The first lining layer (10) constituting the surface in contact with the molten metal (M) in the lining material layer is made of a refractory material, and a sealing material (50) is provided at at least one boundary between the first lining layer (10) and the outer wall (1).

Description

Technical Field

[0001] The present invention relates to a metal melting furnace for holding a molten metal such as aluminum, aluminum alloy, and non-ferrous metal. Background Art

[0002] Conventionally, there has been a melting and holding furnace for melting and holding a molten metal such as aluminum, aluminum alloy, and non-ferrous metal (see, for example, Patent Document 1). The furnace body of a typical melting and holding furnace is composed of a bottom wall and a peripheral wall or side wall extending vertically from the peripheral edge of the bottom wall. The bottom wall and the side wall generally have a lining material such as an outer wall (iron sheet) made of iron, a heat insulating layer, a support layer, and a refractory layer (hereinafter also referred to as refractory or refractory material) in this order from the outside to the inside, and a molten metal storage part for holding the molten metal is formed inside the refractory layer.

[0003] In such a melting and holding furnace, lining materials, particularly the refractory layer in contact with the molten metal, are used, such as precast blocks (fired / non-fired) of shaped refractories, refractory insulating bricks, refractory bricks (fired / non-fired / electroformed), etc., or refractory mortar (thermosetting / aerosetting / hydraulic) of amorphous refractories, castable refractories (previously low-cement), lightweight castable refractories, etc. The molten metal has the property of easily penetrating into the structure of these refractory layers and a reducing power.

[0004] For example, oxides are generated in a molten aluminum alloy (hereinafter also referred to as aluminum melt), and cracks (crazing) that easily cause furnace body damage are likely to occur after long-term use. The aluminum melt penetrates into the cracks in the refractory layer, resulting in molten metal leakage (also referred to as liquid leakage (leakage of molten metal)), and the aluminum melt may sometimes leak outside the molten metal storage part.

[0005] Patent Document 2 discloses a method for detecting solution leakage, which is used to detect the leakage of the molten metal based on the conduction state between a first electrode formed on substantially the entire area of the inner or outer surface of the furnace body and a second electrode immersed in the molten metal inside the furnace body.

[0006] Prior Art Documents

[0007] Patent Documents

[0008] Patent Document 1: Japanese Patent No. 6644776 Gazette

[0009] Patent Document 2: Japanese Unexamined Patent Application Publication No. 2004-58136 Summary of the Invention

[0010] Problems to be Solved by the Invention

[0011] However, Patent Document 2 is a technique for detecting the result of molten liquid leakage on the premise that molten liquid leakage occurs, and it does not prevent molten liquid leakage. In order to prevent molten liquid leakage, there is actually a method of dealing with it by using a refractory material with a thickness of about 100 mm in the refractory layer. However, after about 6 to 8 years from the start of using the furnace, damage caused by cracks may sometimes be found on the furnace body.

[0012] In addition, in the case of continuous operation with only 2 to 4 stops per year for maintenance, it is extremely difficult to prevent molten liquid from leaking to the outside, and it is necessary to concentrate on dealing with the disadvantages in terms of operations such as ensuring the safety of operators or reducing the heat of the molten liquid.

[0013] Therefore, the subject of the present invention is to provide a metal molten liquid furnace that can prevent or suppress molten liquid leakage and can control the leakage direction.

[0014] Means for Solving the Subject

[0015] The means for solving the above subject are as follows.

[0016] A metal molten liquid furnace having an outer wall on its outer peripheral portion and having a molten liquid storage portion for holding a metal molten liquid, characterized in that

[0017] Two or more layers of lining material layers are provided on the inner wall of the metal molten liquid furnace forming the above molten liquid storage portion,

[0018] The first lining layer forming the surface in contact with the above metal molten liquid in the above lining material layer is made of a refractory material,

[0019] A sealing material is provided at at least one boundary between the above first lining layer and the above outer wall.

[0020] Advantages of the Invention

[0021] According to the present invention, it is possible to prevent or suppress molten liquid leakage and to control the leakage direction. Description of the Drawings

[0022] Figure 1 is a cross-sectional view of an example of a metal molten liquid furnace.

[0023] Figure 2 is Figure 1 a cross-sectional view for explaining the molten liquid leakage at the X portion of

[0024] Figure 3 is a cross-sectional view of an example of the sealing material arrangement of the embodiment.

[0025] Figure 4 is a back view of an example of the weaving of the sealing material.

[0026] Figure 5It is a rear view of a weaving example of a sealing material reinforced with reinforcing fibers.

[0027] Figure 6 It is a cross-sectional view of an example of a sealing material configuration of other embodiments.

[0028] Figure 7 It is a cross-sectional view of an example of a sealing material configuration of another embodiment.

[0029] Figure 8 It is a cross-sectional view of an example of a sealing material configuration of yet another embodiment.

[0030] Figure 9 It is a cross-sectional view of an example of a sealing material configuration of different embodiments. Detailed Embodiments

[0031] Hereinafter, embodiments of the present invention will be described.

[0032] As Figure 1 shown, the molten metal furnace has an outer wall 1 on its outer peripheral portion, and two or more layers of lining material layers are provided on the inner wall forming the molten metal storage portion 6 to hold the molten metal M.

[0033] The above-mentioned lining material layer is composed of, for example, a first lining layer 10, a second lining layer 20, and a third lining layer 30 as Figure 1 shown.

[0034] The first lining layer 10 forms a surface in contact with the molten metal M such as aluminum or its alloy, and is made of a refractory material. As the refractory material, for example, a low-cement castable refractory with alumina (Al 2 O 3 ) as the main component is used. As the second lining layer 20 and the third lining layer 30, a fiber or a castable refractory containing at least one of alumina (Al 2 O 3 ) and silica (SiO 2 ) is used to ensure heat insulation and heat resistance.

[0035] As the molten metal furnace, furnaces with various structures can be targeted. Figure 1 The furnace with the structure shown is a molten metal holding furnace for low-pressure casting, and the details are as follows.

[0036] That is, it has a liquid outlet 2 at the upper part, and the liquid outlet 2 is composed of a cylindrical feeder 3. In addition, a gas supply port 4 and an exhaust port 5 are provided at the upper part, and pressurized gas can be supplied and exhausted into the molten metal holding chamber.

[0037] Through a pressurizing device (not shown), pressurized gas such as dry air or inert gas such as argon or nitrogen is sent into the molten metal holding chamber through the gas supply port 4. The molten metal surface is pressurized by the pressurized gas sent into the molten metal holding chamber, and the molten metal rises in the feeder 3 and is pressed into a cavity (not shown) formed in the casting mold through the liquid outlet 2.

[0038] After casting is completed, the supply of pressurized gas from the gas supply port 4 is stopped, and the pressurized gas in the molten metal holding chamber is exhausted from the exhaust port 5.

[0039] In such a molten metal furnace, as described above and as Figure 2 schematically shown (example of the case where the inner lining layer is 4 layers), cracks (crazing) C that are prone to furnace body damage are likely to occur after long-term use. Molten metal, such as aluminum molten metal, penetrates into the cracks in the refractory layer, and sometimes molten metal leakage (also called liquid leakage) occurs. The outer wall 1 is, for example, an outer wall made of iron. In an extreme example, the aluminum molten metal that penetrates into the cracks reaches the outer wall 1, and the outer wall 1 sometimes expands outward due to the heat of the aluminum molten metal. An example of the flow of molten metal leakage is shown by the Figure 2 dashed line.

[0040] Regarding this problem, as Figure 3 shown, at least a sealing material 50 is provided between the first inner lining layer 10 and the second inner lining layer 20 on the outer wall side.

[0041] As this sealing material 50, a sheet-like material, particularly a sheet with a thickness of 2 to 10 mm, can be appropriately used.

[0042] Moreover, the sealing material 50 is particularly preferably a sheet material woven from at least one of ceramic fiber and bio-soluble ceramic fiber and at least one of glass fiber and stainless steel fiber.

[0043] The bio-soluble ceramic fiber used in the present invention is selected from the fibers classified as category 0 (exempt substances) in the "EU Directive 97 / 69 / EC" regulations. Therefore, it is necessary to prove safety by any one of the following 4 animal experiments according to NotaQ "Determination Criteria for Bio-soluble Fibers in the Body", or according to NotaR "Determination Criteria for Non-Inhalable Fibers", for fibers with a value greater than 6 μm obtained by subtracting twice the standard deviation from the length-weighted geometric mean fiber diameter.

[0044] (1) In the in-vivo retention test based on short-term inhalation, fibers with a length greater than 20 μm have a load half-life of less than 10 days;

[0045] (2) In the in-vivo retention test based on short-term intratracheal injection, fibers with a length greater than 20 μm have a load half-life of less than 40 days;

[0046] (3) According to the intraperitoneal administration test, there is no evidence of excessive carcinogenicity;

[0047] (4) In the long-term inhalation test, no relevant pathogenic or neoplastic changes will occur.

[0048] For the bio-soluble ceramic fiber whose safety has been confirmed as above, there are no particular restrictions on its manufacturing method, chemical composition, average fiber diameter or average fiber length. For example, bio-soluble asbestos can also be used.

[0049] Substances containing oxides of alkali metals and alkaline earth metals (Na 2 O, K 2 O, CaO, MgO, BaO, etc.) exceeding 18% by mass can be used.

[0050] Alkaline earth metal silicate cotton such as silica-magnesium oxide-calcium oxide-based can also be used.

[0051] As ceramic fibers, there are known amorphous refractory ceramic fibers (hereinafter referred to as RCF) mainly used at temperatures below 1,400 °C, which are artificial mineral fibers with alumina (Al 2 O 3 ) and silica (SiO 2 ) as the main components, and alumina-based crystalline ceramic fibers used at high temperatures above 1,400 °C. The manufacturing methods, properties, and prices of these RCF and crystalline ceramic fibers are significantly different, and they are used separately according to their respective characteristics.

[0052] The temperature of the molten metal, especially aluminum or aluminum alloy, reaches 700 °C or higher. Therefore, it is preferred to reinforce at least one of the ceramic fiber and the bio-soluble ceramic fiber with at least one of the glass fiber and the stainless steel fiber.

[0053] Especially from the aspect of heat resistance, it is preferred to reinforce with at least stainless steel fiber.

[0054] As the sealing material 50, in order to make it into a sheet, especially a sheet with a thickness of 2 to 10 mm, the fiber filaments (fibers or strands) can be woven into a sheet. The weaving can be, for example, Figure 4 and Figure 5 the plain weave, twill weave, satin weave, and suitable weaving forms shown.

[0055] And, as Figure 5As shown, at least one reinforcing fiber 52 of glass fiber and stainless steel fiber can be woven in an appropriate form into at least one of the first fibers 51A and 51B of ceramic fiber and bio-soluble ceramic fiber. The reinforcing fiber 52 can also be reinforced by being introduced into the strand. Further, the strand into which the reinforcing fiber is introduced can be woven in an appropriate form to form a sheet-like sealing material.

[0056] The sealing material 50 can also be disposed as Figure 6 shown between the second inner lining layer 20 and the third inner lining layer 30 on the outer wall 1 side thereof.

[0057] Furthermore, the sealing material 50 can also be disposed as Figure 7 shown between the third inner lining layer 30 and the fourth inner lining layer 40 on the outer wall 1 side thereof.

[0058] In the present invention, it is only necessary to dispose the sealing material at at least one boundary between the first inner lining layer 10 and the outer wall 1. For example, as Figure 8 shown, the sealing material can be disposed only at the boundary on the outer wall side of the second inner lining layer 20, that is, only between the second inner lining layer 20 and the third inner lining layer 30 on the outer wall 1 side thereof.

[0059] In addition, for example, as Figure 9 shown, the sealing material can be disposed only at the boundary between the outermost inner lining layer ( Figure 9 in the example of Figure 9 is the second inner lining layer 20) and the outer wall 1.

[0060] In addition, after the sealing material 50 is disposed between the inner lining layers as described above, when the molten metal M is initially charged into the molten metal storage portion, the heat of the molten metal M is transmitted to the sealing material 50 through the first inner lining layer 10, and the sealing material 50 sometimes emits a burnt smell. In order to suppress this smell, the sealing material 50 can be fired in advance.

[0061] In addition, in the past, regarding molten metal leakage, the selection of the material of the first inner lining layer has been mainly concerned. However, cracks cannot be avoided in the first inner lining layer 10, there is a possibility of crack generation, and there is a risk of molten metal leakage through the cracks.

[0062] The inventor of the present invention did not focus on the selection of the material of the first inner lining layer 10, and completed the present invention on the premise that cracks are generated in the first inner lining layer 10.

[0063] Even if there is molten metal leakage through the cracks, if it is possible to minimize the leakage amount, reduce the heat, control the leakage direction, and suppress penetration to the outer wall, it is possible to prevent the molten metal from leaking to the outer wall, which is the ultimate goal.

[0064] When using the sealing material of the present invention, especially the heat-resistant (refractory) sealing material, the following advantages are brought.

[0065] (1) It can withstand the temperature of the molten liquid (for example, it can withstand 700 °C when it is aluminum molten liquid).

[0066] (2) It will not contaminate the metal molten liquid in the molten liquid storage part.

[0067] (3) It can reduce the heat of the leaked molten liquid and can inhibit the penetration of the leaked solution before reaching the outer wall.

[0068] (4) It can control the direction when the molten liquid leaks.

[0069] Generally, after the leaked molten liquid descends along the inner liner layers under the action of gravity, when it reaches the inner liner layer on the outer wall side arranged horizontally, it will expand horizontally. Depending on the situation, cracks will occur in the inner liner layer on the outer wall side arranged horizontally, and sometimes the leaked molten liquid will further expand through the cracks under the action of gravity, and the direction of leakage is unpredictable.

[0070] When the sealing material is arranged between the inner liner layers according to the present invention, the sealing material forms an impedance, and the leaked molten liquid is not easy to descend along the inner liner layers under the action of gravity (that is, the descending speed can be inhibited), the heat of the leaked molten liquid between them can be reduced, and the penetration of the leaked molten liquid before reaching the inner liner layer on the outer wall side arranged horizontally can be inhibited. In addition, due to the arrangement of the sealing material, the molten liquid is not easy to directly contact the inner liner layer on the outer wall side, and the generation of cracks is not easy to occur.

[0071] That is, regarding the control of the direction when the molten liquid leaks in the present invention, specifically, it means that by using the sealing material to narrow the space between the inner liner layers to increase the impedance, the speed of the leaked molten liquid is inhibited, and the penetration to the outer wall side is controlled.

[0072] Industrial Applicability

[0073] As the molten liquid, in addition to aluminum or aluminum alloy, it can also be other metal molten liquids.

[0074] Symbol Explanation

[0075] 1... Outer wall, 10... First inner liner layer, 20... Second inner liner layer, 30... Third inner liner layer, 40... Fourth inner liner layer, 50... Sealing material, M... Metal molten liquid.

Claims

1. A metal melt furnace having an outer wall on its outer periphery and comprising a melt storage part for holding the metal melt, Characterized in that, Two or more layers of lining material layers are provided on the inner wall of the metal melt furnace forming the melt storage part, The first lining layer forming the surface in contact with the metal melt in the lining material layer is made of a refractory material, A sealing material is provided at at least one boundary between the first lining layer and the outer wall, The sealing material is a sheet formed by weaving at least one of ceramic fiber and bio-soluble ceramic fiber with at least one of glass fiber and stainless steel fiber, forming a sheet with a thickness of 2 to 10 mm, and is provided in a single layer or a stacked state of multiple layers, The bio-soluble ceramic fiber is selected from the fibers classified as category 0, i.e., exempt substances, in the "EU Directive 97 / 69 / EC" regulation.

2. The metal melt furnace according to claim 1, Wherein, Sealing materials are respectively provided at the boundaries between the first lining layer and the second lining layer on the outer wall side and between the second lining layer and the third lining layer on the outer wall side in the two or more layers of lining material layers.

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