WO2024024288A1

WO2024024288A1 - Molten metal filtration device

Info

Publication number: WO2024024288A1
Application number: PCT/JP2023/021131
Authority: WO
Inventors: 健介中本; 英気堤; 俊昭河野; 稔高岡; 健司藤木
Original assignee: 三井金属鉱業株式会社
Priority date: 2022-07-25
Filing date: 2023-06-07
Publication date: 2024-02-01

Abstract

Provided is a molten metal filtration device in which agitation performance of molten metal, degassing performance against gas inclusions, and prevention of clogging of a filtration tube are made more uniform/improved. Disclosed is a molten metal filtration device that includes: (i) a filtration chamber provided with a molten metal inlet port and outlet port and including a hearth and an inner wall surface; (ii) a filtration unit that is disposed above the hearth inside the filtration chamber and is constituted from a plurality of ceramic filtration tubes for filtering impurities from the molten metal; and (iii) a rotor that agitates the molten metal by rotating in a substantially horizontal direction, the rotor being installed adjacent to the filtration unit, or, when a plurality of filtration units are present, a rotor being installed adjacent to each of the plurality of filtration units, the hearth constituting the lowest point as viewed in the horizontal direction substantially directly below the rotor, excluding the location where a drain channel is installed, which results in substantially an entire portion of contact between the hearth and the inner wall surface being in a position higher than the lowest point substantially directly below the rotor.

Description

Molten metal filtration equipment

The present invention relates to a molten metal filtration device that filters molten metal such as aluminum.

Molten metals such as aluminum used for manufacturing castings usually contain nonmetallic inclusions such as hydrogen and oxides as impurities. For example, dissolved hydrogen in molten metal can form cavities called porosity in castings, and oxides and the like can become inclusions in castings. These cavities and inclusions are undesirable because they can become starting points for fracture of the casting. Therefore, filtration devices have been developed for filtering molten metal and removing inclusions and the like contained in the molten metal. In a molten metal filtration device, molten metal that has been heated and melted at a high temperature is filtered, and the efficiency of filtration is usually affected by the temperature of the molten metal. Therefore, conventional efforts have been made to improve the filtration efficiency by making the temperature of the hot water more uniform within the filtration chamber of a molten metal filtration device, and thereby to improve the filter's clogging prevention performance.

Molten metal filtration devices for achieving such a purpose are disclosed in, for example, Patent Document 1 and Patent Document 2.
That is, in Patent Document 1, in a molten metal filtration device that filters by a group of ceramic filtration tubes of a filtration unit arranged in a filtration chamber, the lowest ceramic filtration tube is placed on the bottom wall of the filtration unit at a lower position. A base block is arranged that can be set from approximately the same height as the upper edge of the inlet to slightly higher than the upper edge of the inlet, the filtration unit is placed on the base block, and molten metal is placed near the filtration unit. A molten metal filtration device is disclosed in which an injection nozzle is arranged to cause convection by gas injection. In addition, Patent Document 2 discloses a molten metal filtration system having the same configuration as Patent Document 1, in which the injection nozzle is fixed to the lower end of a hollow shaft suspended from the lid, and the hollow shaft is movable up and down. An apparatus is disclosed.
Patent Document 1 and Patent Document 2 teach that by providing a molten metal filtration device with these structures, it is possible to improve the filtration efficiency by equalizing the temperature of the hot water and to improve the performance of preventing clogging of the filter. has been done. In this device, gaseous inclusions such as hydrogen are degassed by the gas ejected from the injection nozzle, and the outer surface of the ceramic filtration tube is cleaned to prevent clogging.

Japanese Patent Application Publication No. 7-4868 Japanese Patent Application Publication No. 7-3348

A partial vertical cross-sectional schematic diagram of the molten metal filtration device of Patent Document 1 is shown in FIG. 1 (the outline of the molten metal filtration device of Patent Document 2 is similar to this except for the configuration related to the injection nozzle). This diagram corresponds to a simplified/conceptualized diagram of a part of FIG. 2 of Patent Document 1. In this figure, F is the filtration chamber, T is the ceramic filtration tube (multiple aggregates), I is the molten metal inlet, U is the filtration unit, N is the injection nozzle, W is the inner wall surface of the filtration chamber, and B is the The bottom surface of the filtration chamber (referred to as the hearth), L refers to an imaginary line of the molten metal level (liquid level) when molten metal is supplied to the filtration chamber.
According to the figure, when viewed in a horizontal direction with this molten metal filtration device placed on a horizontal plane, the bottom surface B, which is called the hearth of the filtration chamber F, is located from the side of the inlet I to the opposite side of the filtration chamber. It is continuously lowered toward the inner wall surface W, and the injection nozzle N (which may include a rotor driven by a motor) is disposed above a substantially intermediate position of this slope. Such a continuous slope of the hearth of the filtration chamber is provided to allow the molten metal to flow down by gravity from the filtration chamber F and be discharged.

However, due to the slope of the hearth B of the filtration chamber F, the hot water level on the hearth B (the depth from the hot water level to the hearth ) will be different. As a result of the difference in the hot water level at each position on the hearth of the filtration chamber, uneven convection occurs locally, and at the position opposite to the hot water inlet I where the hot water level is high, bubbles of gas ejected from the injection nozzle occur. As the density becomes smaller, the degassing performance of gaseous inclusions such as hydrogen and the clogging prevention performance by cleaning the outer surface of the ceramic filtration tube become relatively weak and insufficient.
Furthermore, the clogging prevention performance of the ceramic filtration tube due to the ejected gas differs depending on the position on the hearth of the filtration chamber, which results in a difference in the length and shortness of the filtration performance of the ceramic filtration tube. , the operating efficiency of the entire filtration device decreases.

Therefore, the problem to be solved by the present invention is to solve the above-mentioned disadvantages, namely, to improve the stirring performance of molten metal, the degassing performance of gaseous inclusions such as hydrogen, and the performance of ceramics at different positions on the hearth of the filtration chamber. To provide a molten metal filtration device in which the clogging prevention performance of the filtration tube is made more uniform and further improved, and the life of the filtration performance of the ceramic filtration tube is also made uniform.

As a result of intensive research, the present inventors have discovered that a molten metal filtration device is provided with a filtration chamber including an inlet and an outlet for molten metal, a filtration chamber including a hearth and an inner wall surface, and a filtration chamber above the hearth inside the filtration chamber. a filtration unit (s) comprised of a plurality of ceramic filtration tubes arranged to filter impurities from the molten metal; (in some cases, adjacent to each filtration unit), it includes a rotor that stirs the molten metal by rotating in a substantially horizontal direction, and it was observed from the horizontal direction with the molten metal filtration device placed on a horizontal plane. In this case, it has been found that the above problem can be solved by designing the hearth so that the lowest level is located approximately directly below the rotor, excluding the location where the drain flow path is installed. That is, the present inventors have realized that by using a molten metal filtration device having such a configuration, molten metal can be stably filtered at different positions on the hearth of the filtration chamber (both near the inlet and on the opposite side). Uniform convection with no local stagnation occurs, improving the performance of degassing gaseous inclusions such as hydrogen and preventing clogging by cleaning the outer surface of the ceramic filtration tube. discovered that by equalizing the clogging prevention performance of ceramic filtration tubes, the difference in the lifespan of filtration performance of ceramic filtration tubes was reduced, and the operating efficiency of the entire filtration device was improved, and the present invention was completed. I let it happen.

A typical embodiment of the present invention is as follows.
A molten metal filtration device,
(i) A filtration chamber equipped with an inlet and an outlet for molten metal and including a hearth and an inner wall surface;
(ii) a filtration unit arranged above the hearth in the filtration chamber and configured of a plurality of ceramic filtration tubes for filtering impurities from the molten metal; and (iii) the filtration unit. provided that, if there are a plurality of filtration units, it is arranged adjacent to each of the plurality of filtration units, and rotates in a substantially horizontal direction to stir the molten metal. including the rotor,
The hearth is located at its lowest point in a horizontal direction, approximately directly below the rotor, except for the location where the drain flow path is installed, so that substantially the entire contact area between the hearth and the inner wall surface is in contact with the rotor. Exists at a position higher than the lowest point almost directly below the
Molten metal filtration equipment.

According to the molten metal filtration device of the present invention, the molten metal filtration device is arranged adjacent to the filtration unit, but when there are a plurality of filtration units, the molten metal filtration device is arranged adjacent to each of the plurality of filtration units, and is arranged in a substantially horizontal direction. It includes a rotor that stirs the molten metal by rotating, and when observed from the horizontal direction with the molten metal filtration device placed on a horizontal surface, the hearth, excluding the location where the drain flow path is installed, is: By designing the lowest level approximately directly below the rotor, the molten metal remains stable and stable at different locations on the hearth of the filtration chamber (both near the inlet and on the opposite side). Uniform convection without local stagnation occurs, which further improves the degassing performance of gaseous inclusions such as hydrogen and the anti-clogging performance by cleaning the outer surface of the ceramic filtration tube, and also improves the ability to clean the outside of the ceramic filtration tube at different locations on the hearth of the filtration chamber. The structure of the conventional molten metal filtration equipment is such that the clogging prevention performance of the ceramic filtration tubes is made uniform, which in turn reduces the difference in the lifespan of the filtration performance of the ceramic filtration tubes, and improves the operating efficiency of the entire filtration equipment. This provides unforeseeable benefits.

FIG. 1 shows a schematic diagram/conceptual diagram of a partial longitudinal cross-sectional side view of a molten metal filtration device disclosed in Patent Document 1: Japanese Unexamined Patent Publication No. 7-4868 (prior art). FIG. 2 shows a schematic diagram/conceptual diagram of a longitudinal side surface of a molten metal filtration device according to an embodiment of the present invention. FIG. 3 shows a vertical cross-sectional side view of a molten metal filtration device according to an embodiment of the present invention. FIG. 4 shows a sectional view taken along line AA of the molten metal filtration device shown in FIG. FIG. 5 shows a BB sectional view of the molten metal filtration device of FIG. 3. FIGS. 6A to 6F are views illustrating various embodiments of the rising portion formed on the bottom surface (hearth) of the filtration chamber of the molten metal filtration apparatus according to the present invention.

A molten metal filtration device according to an embodiment of the present invention will be explained using a schematic longitudinal side view (conceptual diagram) shown in FIG. 2. FIG. 2 is a diagram of a vertical side surface of the molten metal filter device, observed from the horizontal direction, with the device disposed on a horizontal plane.

In FIG. 2, 1 is a molten metal filtration device, 2 is a filtration chamber, 3 is an inlet, 4 is an outlet, 5 is a bottom surface of the filtration chamber (hereinafter referred to as the hearth), 6 is an inner wall surface of the filtration chamber, 7 8 is a heater, 8 is a filtration unit composed of a plurality of ceramic filtration tubes 8a above the

hearth

5, 9 is a rotor provided adjacent to the filtration unit 8, and H is one of the horizontal lines indicating the horizontal direction. It is. The plurality of ceramic filtration tubes 8a are arranged horizontally in the direction of the paper at predetermined intervals. In this figure, two filtration units are provided as a typical example, but there may be one filtration unit, or there may be three or more filtration units. The matters described below for embodiments in which two filtration units are provided apply to embodiments in which one or more filtration units are provided, unless there are technically unacceptable reasons. may be applied as well.

When pouring and filtering molten metal, molten metal such as aluminum or aluminum alloy containing non-metallic inclusions is supplied into the filtration chamber 2 from the inlet 3, as shown by the arrow in FIG. Ru. This molten metal is heated by the heater 7, and non-metallic inclusions are filtered by the ceramic filter tube 8a of the filter unit 8. Next, the filtered purified molten metal is discharged from the outlet 4. During the filtration process in the filtration chamber, the molten metal is stirred by rotation of the rotor 9 in a substantially horizontal direction, and the temperature of the molten metal is made uniform.

With the molten metal filtration device 1 having such a configuration, when charging and filtering molten metal, the rotor 9 is filtered at both the location near the inlet 3 on the hearth 5 of the filtration chamber 2 and the opposite side thereof. The molten metal level above the hearth is relatively lower than that directly below it (the depth from the molten metal surface to the hearth is smaller), and the molten metal remains stable and does not stagnate locally even at a position away from the rotor 9. Uniform convection occurs, which provides the advantage of further improving the degassing performance of gaseous inclusions such as hydrogen and the clogging prevention performance by cleaning the outer surface of the ceramic filtration tube 8a.
Furthermore, when pouring and filtering molten metal, the metal level is relatively lower both on the hearth 5 of the filtration chamber 2 near the inlet 3 and on the opposite side than almost directly below the rotor 9. By making the clogging prevention performance of the ceramic filtration tubes more uniform at different positions on the hearth 5 of the filtration chamber 2, the difference in the lifespan of the filtration performance of the ceramic filtration tubes 8a is reduced.

Furthermore, a molten metal filtration device according to an embodiment of the present invention will be explained using FIGS. 3 to 5. FIG. 3 is a diagram of a longitudinal side surface of the molten metal filtering device observed from the horizontal direction, with the device disposed on a horizontal plane. FIG. 4 shows a sectional view taken along line AA of the molten metal filtration apparatus shown in FIG. 3, and FIG. 5 shows a sectional view taken along line BB of the molten metal filtration apparatus shown in FIG.
Note that in FIGS. 3 to 5, the same reference numerals are used for functionally common members as in FIG. 2.

3 to 5, 1 is a molten metal filtration device, 2 is a filtration chamber, 3 is a hot water inlet, 4 is a hot water outlet, 5 is a flat part 5a near the center of the hearth (substantially directly below the rotor), and a rising part 5b. and a bottom surface (hearth) of the filtration chamber consisting of a

drain channel

5c, 6 an inner wall surface of the filtration chamber, 7 a heater, 8 a plurality of ceramic filtration tubes 8a above the hearth 5, and a wedge member. 8b is a filtration unit; 9 is a rotor consisting of a motor 9a, a rotary rod 9b and a tip member 9c; 10 is a base of the filtration unit 8; 11 is a casing of the filtration chamber that accommodates the filtration chamber 2; This is an imaginary line of the surface of molten metal when it is being poured and filtered.

In FIGS. 3 to 5, two filtration units are typically provided, but there may be one filtration unit, or there may be three or more filtration units. The plurality of ceramic filtration tubes 8a are arranged horizontally in the direction of the paper at predetermined intervals. Substantially the entirety of the filtration chamber 2, except for the inlet 3, the outlet 4, and the vicinity of the motor 9a of the rotor 9, is housed in a casing 11 of the filtration chamber. The casing 11 of the filtration chamber is generally made entirely of metal, and is also called a can body.

Usually, molten metal such as aluminum or aluminum alloy containing non-metallic inclusions heated from about 500°C or higher to about 800°C flows from the inlet 3 to the filtration chamber 2 as shown by the arrow in FIG. supplied within. The opening area of the inlet 3 is appropriately designed in accordance with the desired amount of filtration by the molten metal filtration device 1. The inlet 3 is preferably connected to an inclined or substantially vertical flow path so that the supplied molten metal can flow down by gravity.

The molten metal entering from the inlet 3 is preferably maintained at its calorific value by a heater 7 provided in the filtration chamber, or is further heated to a high temperature. As the heater 7, several heaters are installed at approximately equal intervals in the vicinity of the inner wall surface 6 having the hot water inlet 3 in the filtration chamber 2 and in the vicinity of the inner wall surface 6 on the opposite side from the hot water inlet 3 in the figure. A long cylindrical heater is installed vertically. The heater 7 is not limited to the illustrated shape, number, or installation location as long as it can heat the molten metal; for example, the cross-sectional shape may be partially or entirely elliptical or rectangular. Further, the heater 7 may be installed in a single unit or in a plurality (for example, 2 to 20 units) at a predetermined position, or may be installed at a position away from the inner wall surface. . When the heater 7 is installed in the vicinity of the inner wall surface 6 having the hot water inlet 3 in the filtration chamber 2, the molten metal may directly contact the ceramic filtration tube 8a of the filtration unit 8 disposed nearby. In order to prevent non-uniform life between the tubes and a decrease in filtration efficiency, it is preferable to provide a shielding wall (not shown) between the heater 7 and the filtration unit 8 at the relevant position.

Although not particularly limited, the filtration chamber 2 may typically have a hexahedral shape such as a rectangular parallelepiped or a cube on its inner surface. The inner surface of the filtration chamber 2 is formed by a hearth 5 which is the bottom surface thereof, inner wall surfaces 6 of the filtration chamber on all four sides, and a lid body covering above them (the bottom surface of the lid body forms the top surface of the filtration chamber). There is. It is preferable that the inner wall surface 6 forms a substantially vertical wall surface (perpendicular to the horizontal plane).

As shown in FIGS. 3 to 5, a pedestal 10 is disposed at a predetermined location (usually multiple locations) near the inner wall surface 6 of the hearth 5 of the filtration chamber 2. A filtration unit 8 (two units are shown in the figure, but it may be a single unit or three or more units) is stably installed and fixed. The shape and number of the pedestals 10 of the filtration unit 8 (single or plural) are not particularly limited as long as the filtration unit 8 can be firmly fixed (immovably) substantially horizontally. When a plurality of pedestals 10 are arranged, it is desirable that they be arranged in symmetrical positions with respect to each surface of the inner wall surface 6 in the vicinity thereof. Moreover, the filtration unit 8 may be fixed to the inner wall surface 6 via a wedge member 8b, as shown in FIGS. 4 and 5. The shape of the wedge member 8b is configured such that the filtration unit 8 can be fixed to the inner wall surface 6 with good durability, and the number thereof may be one or two or more (in FIG. 5, one A case is illustrated in which three wedge members 8b are provided for one filtration unit 8).

Each filtration unit 8 is usually composed of a plurality of ceramic filtration tubes 8a arranged horizontally at approximately equal intervals. The number of ceramic filtration tubes 8a constituting each filtration unit 8 is not particularly limited as long as it is a plurality of pieces, for example, 2 to 50 pieces, 3 to 40 pieces, 4 to 30 pieces, or 5 pieces. The number may be from 1 to 20. The cross-sectional shape of the ceramic filtration tube 8a may normally be approximately circular, but may also be approximately elliptical or rectangular, or a combination thereof. The plurality of ceramic filtration tubes 8a constituting each filtration unit 8 are usually horizontally arranged horizontally and at approximately equal intervals, but at least some of the adjacent ceramic filtration tubes may be in direct contact with each other. . In the filtration unit 8, when the ceramic filtration tubes 8a arranged horizontally in a substantially horizontal manner and at substantially equal intervals form a plurality of rows, it is preferable that the plurality of rows are also arranged at substantially equal intervals.

As shown in FIGS. 3 to 5, the rotor 9 usually includes at least a motor 9a, a rotating rod 9b, and a tip member 9c. The rotor 9 is arranged adjacent to the filtration unit 8 (if there are a plurality of filtration units 8, adjacent to each of them). As shown in the figure, the rotor 9 is normally arranged above the center of the hearth 5 so that the effect of agitation extends throughout the inside of the filtration chamber 2, but the rotor 9 is not limited thereto. When there is only one filtration unit 8, the rotor 9 is arranged above a position away from the vicinity of the center of the hearth 5 (for example, at a position approximately midway between the vicinity of the center of the hearth 5 and the inner wall surface 6). Good too. When two or more filtration units 8 are installed, it is preferable that the rotor 9 is arranged at approximately the same distance from each filtration unit. The number of rotors 9 installed is usually one, but a plurality of rotors 9 can also be installed. When a plurality of rotors 9 are installed, each rotor is preferably adjacent to the filtration unit 8, and each rotor is spaced approximately equidistantly from the filtration unit (or neighboring filtration unit if multiple rotors are installed). It is also preferable that the In addition, when a plurality of rotors 9 are installed, the hearth 5 is located at the lowest position (as seen in the horizontal direction) approximately directly below at least one rotor among the plurality of rotors, excluding the location where the drain passage is installed. (the lowest level).

The motor 9a of the rotor 9 is a member that rotates the rotating rod 9b and the tip member 9c at a variable speed. The motor 9a of the rotor 9 may be provided with a speed reduction mechanism, and may also be provided with a heater and a fan for heating the molten metal. The rotating rod 9b of the rotor 9 is not particularly limited, but from the viewpoint of stirring efficiency, its rotation axis is set in a substantially vertical direction (that is, a direction vertically traversing the filtration chamber 2 of the molten metal filtration device 1 arranged on a horizontal plane). It is preferable that there be. It is preferable that the tip member 9c of the rotor 9 has a gas injection function for promoting convection and stirring of the molten metal. When the tip member 9c of the rotor 9 has a gas injection function, the rotating rod 9b may be configured to have a hollow shaft shape, and the gas for injection may be supplied through this hollow shaft. In this case, the tip member 9c may be formed with a plurality of gas injection ports. The injection gas is not particularly limited, but is preferably an inert gas such as nitrogen or argon.

The tip member 9c of the rotor 9 may also have a blade/impeller shape instead of or in addition to the gas injection mechanism to promote convection and stirring of the molten metal. In order to promote convection and stirring of the molten metal, the tip member 9c of the rotor 9 is configured to be movable up and down together with the rotating rod 9b instead of or in addition to the gas injection mechanism and/or the blade impeller shape. You can leave it there. In this case, a vertical movement mechanism for the rotating rod 9b and the tip member 9c may be further provided near the motor 9a of the rotor 9.

The molten metal that enters from the inlet 3 is preferably maintained at its calorific value by a heater 7 provided in the filtration chamber, or is further heated to a high temperature, and is passed through a plurality of ceramic filtration tubes 8a while being convected and stirred by a rotor 9. It is subjected to filtration by a filtration unit 8 consisting of: When filtration is performed by the filtration unit 8, the level of the molten metal is set to such a level that the entire filtration unit 8 (all of them if a plurality of filtration units 8 are provided) is immersed in the molten metal. (The imaginary line of the molten metal surface is indicated by M in FIGS. 3 and 4). The filtered molten metal is discharged from the tap 4. Although two tap holes 4 are illustrated in FIG. 5, the number is not limited to two, and the number may be one or three or more. Like the inlet 3, the opening area of the outlet 4 is appropriately designed in accordance with the desired amount of filtration by the molten metal filtration device 1. The tap 4 may include, but is not particularly limited to, a rising portion as illustrated in FIG. 4 .

In FIGS. 3 to 5, the hearth 5 consists of a flat portion 5a near the center, a rising portion 5b, and a drain channel 5c. There are no particular limitations on the shape of the hearth 5, except that it must be designed to be at its lowest level at a position approximately directly below the rotor 9, excluding the location where the drain channel 5c is installed, when viewed in the horizontal direction. Not done. In addition, when a plurality of rotors 9 are installed, the hearth 5 is located at the lowest position (as seen in the horizontal direction) approximately directly below at least one rotor among the plurality of rotors, excluding the location where the drain passage is installed. (the lowest level).

In one embodiment, the area of the flat portion 5a may be 2% or more and 40% or less, preferably 3% or more and 30% or less, of the horizontal area of the entire hearth, from the viewpoint of stirring efficiency, and further Preferably, it may be 5% or more and 20% or less. Further, from the viewpoint of stirring efficiency, the area of the flat portion 5a may be 80% or more and 300% or less, preferably 100% or more and 200% or less, of the horizontal rotation area of the tip member 9c of the rotor 9.

The drain flow path 5c is a flow path for draining the remaining molten metal (molten metal containing impurities or precipitated substances, or molten metal discharged during equipment maintenance) under its own weight. Functionally, the drain flow path 5c needs to form a descending portion over substantially the entire length from the hearth to the discharge port, as illustrated in FIG. Therefore, when designing the hearth 5 to have its lowest level at a position substantially directly below the rotor 9 when viewed in the horizontal direction, the level at the location where the drain flow path 5c is installed is excluded from consideration in the design. Although the shape of the drain flow path 5c may be arbitrarily designed, draining the remaining hot metal may be facilitated by making the width of the downstream flow path wider than that of the upstream flow path (see FIG. 5).

Due to this design of the hearth 5, almost the entire contact area between the hearth 5 and the inner wall surface 6 is located at a position higher than the lowest point almost directly under the rotor 9, so that when pouring and filtering molten metal, , both on the hearth 5 of the filtration chamber 2 near the hot water inlet 3 and on the opposite side, the hot water level above the hearth is relatively lower than that directly below the rotor 9 (from the hot water surface to the hearth). ), stable and uniform convection of the molten metal without local stagnation occurs, which in turn improves the ability to degas gas inclusions such as hydrogen and prevent clogging by cleaning the outer surface of the ceramic filtration tube. further improves. Such a design further equalizes the anti-clogging performance of the ceramic filtration tubes at different positions on the hearth of the filtration chamber, which in turn reduces the difference in the lifespan of the filtration performance of the ceramic filtration tubes, improving production efficiency. It helps to improve and reduce the cost of the entire production line.

The angle α of a straight line connecting the lowest point approximately directly below the rotor 9 on the hearth 5 (if it has a flat part 5a, its center point) and any contact part of the hearth 5 and the inner wall surface 6 with respect to the horizontal plane is: Although not particularly limited, from the viewpoint of obtaining the above-mentioned desired effects and preventing the uneven distribution of impurities due to excessively large height difference of the hearth, the temperature may be generally 2 degrees or more and 30 degrees or less, and is preferably may be 3 degrees or more and 25 degrees or less, 4 degrees or more and 20 degrees or less, or 5 degrees or more and 15 degrees or less.

As shown in FIGS. 3 to 5, from the viewpoint of stirring efficiency, it is preferable that the hearth 5 has a flat portion 5a at a position substantially directly below the rotor 9 (near the center in this figure). It is not essential to provide such a flat portion at a position substantially directly below the rotor 9 of the hearth 5, and this position may also form a part of the rising portion. In addition, in FIGS. 3 and 4, the rising portion 5b of the hearth 5 is illustrated as a cross section of a rising straight line having a constant slope (rising angle), but the rising portion 5b of the hearth 5 is located approximately directly below the rotor 9 of the hearth 5. It is not necessary to form a continuous rise (for example, a rising slope or a rising step) in all parts in a predetermined direction from the hearth 5 to the contact portion between the hearth 5 and the inner wall surface 6. The rising portion 5b of the hearth 5 may be raised in at least a portion, preferably a majority, of the vertical cross section in a predetermined direction, and may be flat in a portion (single portion or multiple portions) where it is not raised. (a portion forming a substantially horizontal surface). The rising portion 5b of the hearth 5 may include, at least in part, a step portion (consisting of one or more steps that are a combination of a substantially vertical step portion and a substantially horizontal portion).

FIGS. 6A to 6F illustrate some non-limiting embodiments of the cross-section of the rising portion formed in the hearth of the filtration chamber of the molten metal filtration device according to the present invention. .
In the figure, the hearth of the filtration chamber has, in a vertical section in a predetermined direction, an ascending straight line with a certain slope (rising angle) or a certain step from the lowest point toward the contact area between the hearth and the inner wall surface. In addition to the ascending staircase, it may include a concave ascending section like S1 and/or a convex ascending section like S2.
In addition, in a vertical section in a predetermined direction, the hearth of the filtration chamber rises in a straight line with a certain slope (rising angle) or rises with a certain step from the lowest point toward the contact area between the hearth and the inner wall surface. In place of or in addition to the cross-sectional shapes such as stairs, S1 and/or S2, ascending gradients with a flat part (approximately horizontal part) interposed in a part such as S3, and/or a part such as S4 may include an ascending slope with a step part (a combination of a substantially vertical step part and a substantially horizontal part) interposed therebetween.
In addition, in a vertical section in a predetermined direction, the hearth of the filtration chamber rises in a straight line with a certain slope (rising angle) or rises with a certain step from the lowest point toward the contact area between the hearth and the inner wall surface. In place of, or in addition to, at least one of the stairs, S1, S2, S3 and S4, an ascending slope with increasing slope (i.e. the slope is successively larger) such as S5 and/or an ascending slope such as S6. It may include a step-like rising portion in which the step height gradually increases (that is, the step height gradually increases). Alternatively, the hearth of the filtration chamber may have an ascending slope with a gradually decreasing slope (i.e., the slope is gradually decreasing) and/or a step-like structure with gradually decreasing steps (i.e., the steps are gradually decreasing) such as S6. May include a rising part.
The hearth of the filtration chamber may be formed from a combination of two or more different cross-sectional shapes in a vertical section in any of a plurality of directions from the lowest level toward the contact portion between the hearth and the inner wall surface. Further, the hearth of the filtration chamber may be formed to have substantially the same cross-sectional shape in any two symmetrical directions from the lowest level toward the contact portion between the hearth and the inner wall surface.
By allowing such a wide variety of hearth cross-sectional shapes, the degree of freedom in hearth design is greatly increased, allowing for various variable designs such as filtration throughput of molten metal, heating temperature, rotor configuration, etc. It becomes easy to maximize the filtration efficiency and further equalize the life of the filtration performance of the ceramic filtration tube by adapting it to the elements.

F: Filtration chamber T: Ceramic filtration tube I: Molten metal inlet U: Filtration unit N: Injection nozzle W: Inner wall of the filtration chamber B: Bottom of the filtration chamber/hearth L: Imagination of the surface of the molten metal (The above symbols F to L refer to FIG. 1 illustrating the prior art.)
1: Molten metal filtration device 2: Filtration chamber 3: Inlet 4: Outlet 5: Hearth (bottom of filtration chamber)
5a: Plane part near the center of the hearth (substantially directly under the rotor) 5b: Rising part of the hearth 5c: Drain channel formed in the hearth 6: Inner wall surface 7: Heater 8: Filtration unit 8a: Ceramic filtration Tube 8b: Wedge member 9: Rotor 9a: Motor 9b: Rotating rod 9c: Tip member 10: Pedestal 11: Case of filtration chamber S1: Concave curved ascending slope cross section formed on the hearth S2: Formed on the hearth S3: An ascending slope cross section with a flat part formed on the hearth S4: An ascending slope cross section with a stepped part formed on the hearth S5: A slope formed on the hearth S6: A cross-section of a step-like rising part where the steps formed on the hearth gradually increase.

Claims

A molten metal filtration device,
(i) A filtration chamber equipped with an inlet and an outlet for molten metal and including a hearth and an inner wall surface;
(ii) a filtration unit arranged above the hearth in the filtration chamber and configured of a plurality of ceramic filtration tubes for filtering impurities from the molten metal; and (iii) the filtration unit. provided that, if there are a plurality of filtration units, it is arranged adjacent to each of the plurality of filtration units, and rotates in a substantially horizontal direction to stir the molten metal. including the rotor,
The hearth is located at its lowest level in a horizontal direction, approximately directly below the rotor, except for the location where the drain passage is installed, so that substantially the entire contact area between the hearth and the inner wall surface is in contact with the rotor. Exists at a position higher than the lowest point approximately directly below the
Molten metal filtration equipment.
The hearth according to claim 1, wherein the hearth includes an ascending slope in the horizontal direction and/or a step-like rising part from the lowest level toward at least a part of the contact area between the hearth and the inner wall surface. Molten metal filtration equipment.
The ascending slope of the hearth in the horizontal direction has different slopes at different positions of the hearth, and/or the stepped rising portion of the hearth has different steps at different positions of the hearth. The molten metal filtration device according to claim 2, comprising:
The slope of the ascending slope of the hearth in the horizontal direction includes a portion where the gradient gradually increases from the lowest point toward at least a portion of the contact portion between the hearth and the inner wall surface, and/or 4. The step-like rising portion of the hearth includes a portion where the step height gradually increases from the lowest level toward at least a portion of the contact portion between the hearth and the inner wall surface. Molten metal filtration equipment.
The molten metal filtration device according to claim 2, wherein the ascending slope of the hearth with respect to the horizontal direction forms a curved surface on at least a portion of the hearth.
The filtration unit is composed of a plurality of ceramic filtration tubes arranged in parallel at substantially equal intervals in a substantially horizontal direction,
When there are a plurality of filtration units, the rotor is arranged at approximately the same distance from each of the plurality of filtration units.
The molten metal filtration device according to claim 1 or 2.
3. The rotor according to claim 1 or 2, wherein the rotor has a rotating shaft extending in a substantially vertical direction located substantially in the center of the filtration chamber, and includes a gas injection mechanism for promoting convection of molten metal. Molten metal filtration equipment.