Molten metal filtration unit

Abstract

The present invention addresses the problem of providing a molten metal filtration unit that is stably disposed inside a filtration chamber. The problem is resolved by this molten metal filtration unit that comprises a pair of side plates and substantially cylindrical filtration tubes connected to each of the pair of side plates in a substantially perpendicular manner, wherein: the pair of side plates are provided with a first side plate provided with through-holes at the locations connected to the filtration tubes, and a second side plate in which the portions connected to the filtration tubes are closed; the side plates are provided with leg parts suspended from the bottom surface of each side plate; and the number of leg parts provided to the first side plate is at least one greater than the number of leg parts provided to the second side plate.

Description

Molten metal filtration unit

[0001] The present invention relates to a molten metal filtration unit to be installed in a molten metal filtration apparatus that filters molten metal such as aluminum. More specifically, the present invention relates to a molten metal filtration unit that facilitates installation of the filtration chamber at a predetermined position when the molten metal filtration unit is installed in the filtration chamber of the molten metal filtration apparatus.

[0002] Molten metals such as aluminum used in the production of castings typically contain impurities such as hydrogen and non-metallic inclusions, such as oxides. For example, dissolved hydrogen in the molten metal can form cavities called porosity in the casting, and oxides and other substances can become inclusions in the casting. These cavities and inclusions are undesirable because they can be the starting point for fracture in the casting. Therefore, filtration devices have been developed to filter the molten metal and remove impurities such as inclusions contained in the molten metal.

[0003] To achieve this purpose, a molten metal filtration device is typically used in which a molten metal filtration unit having a plurality of ceramic filtration tubes for filtering impurities from the molten metal is placed in a filtration chamber provided with an inlet and an outlet (see Patent Document 1). In such a molten metal filtration device, when the molten metal filtration unit is placed in the filtration chamber, it is necessary to bring the molten metal filtration unit into close contact with the outlet side of the filtration chamber in order to prevent leakage of the molten metal.

[0004] Therefore, the position and height of the molten metal filtration unit have been adjusted as needed by using a block for adjusting the height of the molten metal filtration unit on the hearth of the filtration chamber.

[0005] JP 2014-210254 A

[0006] The filtration chamber of a repeatedly used molten metal filtration device expands and contracts repeatedly due to the heat of the high-temperature molten metal as the molten metal is repeatedly filtered. Furthermore, the base part of the hearth that comes into contact with the filtration unit wears out as the filtration unit is repeatedly installed. As a result, the hearth of the filtration device becomes less level due to aging, making it difficult to stably position the filtration unit within the filtration chamber.

[0007] Therefore, the problem to be solved by the present invention is to provide a molten metal filtration unit that eliminates the above-mentioned disadvantages, i.e., that can be stably arranged in a filtration chamber. Note that throughout this specification, the "molten metal filtration unit" may also be referred to simply as the "filtration unit." Also, throughout this specification, the "molten metal filtration device" may also be referred to simply as the "filtration device."

[0008] As a result of extensive research, the inventors discovered that the above-mentioned problems could be solved by improving the legs provided on the bottom surfaces of the side plates that constitute the filtration unit, and thus completed the present invention. Note that in the above explanation and this specification, the term "first side plate" refers to a side plate that has a through-hole at the location connected to the filtration tube, and the term "second side plate" refers to a side plate that has a closed location connected to the filtration tube.

[0009] A typical aspect of the present invention is as follows: A molten metal filtering unit comprising a pair of side plates and a substantially cylindrical filter tube connected substantially perpendicularly to each of the pair of side plates, wherein the pair of side plates comprises: a first side plate having a through hole at a location connected to the filter tube, and a second side plate the location connected to the filter tube is closed, each side plate has a leg extending downward from a bottom surface of the side plate, and the number of legs provided on the first side plate is at least one more than the number of legs provided on the second side plate.

[0010] According to the filtration unit of the present invention, by making the number of legs provided on the first side panel at least one more than the number of legs provided on the second side panel, the legs come into contact with the hearth, thereby achieving stable placement of the filtration unit even in an aged filtration chamber. Furthermore, the filtration unit has an additional excellent advantage in that heat can circulate between the legs, thereby improving the preheating efficiency of the filtration device.

[0011] Fig. 1 shows a typical example of a filtration unit and a filtration device. Fig. 2 shows a schematic diagram of a filtration unit according to one embodiment of the present invention. Fig. 3 shows a front view of a first side plate of a filtration unit according to one embodiment of the present invention. Fig. 4 shows a front view of a second side plate of a filtration unit according to one embodiment of the present invention. Fig. 5 is a graph showing the time change in the controlled temperature by the heater and the time change in the temperature of the filtration units of Example 1 and Comparative Example 1 in a preheating evaluation.

[0012] The filtration unit of the present invention is used by being placed in a filtration chamber of a filtration device. To facilitate understanding of the features of the filtration unit of the present invention, a typical filtration unit and filtration device will first be described with reference to FIG.

[0013] 1 shows a filtration device 101, which includes an inlet 102, a filtration chamber 103, a tapping chamber 105, and tapping outlets 106 and 110. The filtration unit 104 includes a first side plate 107, a second side plate 108, and a substantially cylindrical filtration tube 109 connected substantially perpendicularly to the side plates. Although not shown in FIG. 1, the first side plate 107 has a through-hole at the location connected to the filtration tube 109, and the second side plate 108 has a closed location connected to the filtration tube 109.

[0014] 1 is a schematic view of the entire filtration device observed from a direction in which the longitudinal direction of the filtration tube is approximately horizontal, the first side plate is located on the left side of the filtration tube, and the second side plate is located on the right side of the filtration tube. In this specification, unless otherwise specified, the filtration unit and the filtration device will be described assuming that they are observed from the same direction.

[0015] In molten metal filtering, a filtration unit 104 is disposed in a filtration chamber 103, and molten metal, such as aluminum or an aluminum alloy, is supplied to the inlet 102. The molten metal supplied from the inlet 102 passes through a filtration tube 109 provided in the filtration unit 104 disposed in the filtration chamber 103, thereby removing impurities such as oxides contained in the molten metal. The filtered molten metal flows from the filtration tube 109 through a through-hole provided in the first side plate 107, into the tapping chamber 105 from the tapping outlet 110, and then passes through the tapping chamber 105 before being discharged from the tapping outlet 106. The discharged molten metal is sent to a molten metal storage device, a metal processing device (neither of which are shown) that processes the molten metal, or the like.

[0016] In general, the filtering device 101 filters SiC aggregate into Si ３ N ４ The size of the filtration device 101 is not particularly limited as long as the filtration unit 104 can be placed in the filtration chamber 103.

[0017] In the filtration unit of the present invention, each side plate has a leg hanging down from the bottom surface of the side plate, and the number of legs provided on the first side plate is at least one more than the number of legs provided on the second side plate.

[0018] In such a filtration unit, for example, when the second side plate has one leg, the first side plate has two or three or more legs. Furthermore, when the second side plate has two legs, the first side plate has three or four or more legs. Furthermore, when the second side plate has three legs, the first side plate has four or five or more legs. Furthermore, when multiple legs are provided on either or both side plates, it is preferable that the multiple legs on each side plate be located symmetrically with respect to approximately the center point of the bottom surface of the side plate in the longitudinal direction. When multiple legs are provided on either or both side plates, it is preferable that the heights (vertical dimensions) of the multiple legs on each side plate be approximately the same.

[0019] Due to the above-mentioned configuration, the filtration unit of the present invention can be stably positioned within the filtration chamber because all of the legs of the filtration unit can be in contact (or substantially in contact) with the hearth even if distortion occurs in the hearth.

[0020] Furthermore, the filtration device requires preheating after the filtration unit is placed and before the molten metal is poured in. The filtration unit of the present invention has the above-described configuration, which allows heat to circulate between the legs, thereby shortening the time required to reach the target temperature compared to conventional filtration units and improving preheating efficiency.

[0021] Furthermore, when filtration of molten metal is performed using a filtration device, the filtration unit of the present invention has less friction with the hearth than conventional filtration units, and therefore is less likely to interfere with thermal expansion of the filtration unit itself, preventing leakage of the molten metal due to cracks in the filtration unit caused by thermal expansion, and making it possible to provide high-quality molten metal.

[0022] In one aspect of the present invention, the filtration unit may have two legs on the first side plate and one leg on the second side plate.

[0023] By configuring the filtration unit in this way, the filtration unit has three legs. Therefore, the bottoms of the three legs (the lowest vertical positions) of the filtration unit are on the same plane, and even if the hearth in the filtration chamber has become distorted due to aging, the bottoms of all the legs are in contact with the hearth support (base). As a result, the filtration unit can be stably placed in the filtration chamber.

[0024] In one aspect of the present invention, the molten metal filtration unit may have two legs near both longitudinal ends of the bottom surface of the first side plate, and one leg at approximately the longitudinal center of the bottom surface of the second side plate.

[0025] By configuring the filtration unit in this manner, the filtration unit can be more stably disposed within the filtration chamber.

[0026] In one aspect of the present invention, when the molten metal filtration unit is placed on a horizontal surface and observed vertically from above, the area of ​​the molten metal filtration unit, which is expressed as the product of the length of the molten metal filtration unit in the longitudinal direction of the filtration tube and the longitudinal length of the side plate, is defined as S1, and the total area of ​​the contact areas of all the legs of the molten metal filtration unit is defined as S2. The area ratio S2 / S1 may be 0.0020 or more and 0.015 or less.

[0027] S1 may correspond to the base area when the filtration unit is considered as a rectangular parallelepiped. S2 may be calculated from the dimensions of the bottom surface of the legs when the bottoms of the legs are flat. The contact area of ​​the legs may also be measured by applying ink to the legs and measuring ink marks, or by placing the filtration unit on pressure-sensitive paper and measuring marks left behind.

[0028] The area ratio S2 / S1 may be 0.0020 or more and 0.015 or less, preferably 0.0020 or more and 0.0133 or less, and more preferably 0.0020 or more and 0.0093 or less. When the area ratio S2 / S1 is within the above range, heat can circulate between the legs, shortening the time required to reach the target temperature and improving preheating efficiency.

[0029] Hereinafter, an embodiment of the present invention will be described with reference to the drawings, but the present invention is not limited to the embodiment shown in the drawings.

[0030] FIG. 2 shows a filtration unit according to one embodiment of the present invention. However, since FIG. 2 is for illustrative purposes, the dimensional ratios and the number of filtration tubes may differ from the actual figures. The filtration unit 104 according to the present invention has legs 201 on the bottom surface of the first side plate 107 and legs 202 on the bottom surface of the second side plate 108. FIG. 3 shows the first side plate of a filtration unit according to one embodiment of the present invention. That is, FIG. 3 shows the filtration unit in FIG. 2 as viewed from the left side of the figure. FIG. 4 shows the second side plate of a filtration unit according to one embodiment of the present invention. That is, FIG. 4 shows the filtration unit in FIG. 2 as viewed from the right side of the figure.

[0031] Therefore, in one aspect of the present invention, the first side plate can be provided with two legs 201 as shown in Fig. 3, and the second side plate can be provided with one leg 202 as shown in Fig. 4. As described above, with this configuration, even if distortion occurs in the hearth, the legs 201 and 202 of the filtration unit can be in contact with the hearth, so the filtration unit 104 can be stably arranged in the filtration chamber.

[0032] In addition, in this embodiment, heat can circulate between the two legs 201 in Figure 3 and from both sides of the leg 202 in Figure 4, so the time required to reach the target temperature during preheating is shorter than in conventional filtration units, and preheating efficiency can be improved.

[0033] Furthermore, in this embodiment, two legs 201 can be provided near both longitudinal ends of the bottom surface of the first side plate as shown in Figure 3, and one leg 202 can be provided at approximately the center of the longitudinal direction of the bottom surface of the second side plate as shown in Figure 4.

[0034] Furthermore, in this embodiment, as described above, the area ratio S2 / S1 may be 0.0020 or more and 0.015 or less. Here, the area S1 of the molten metal filtration unit is expressed as the product of the length of the molten metal filtration unit in the longitudinal direction of the filter tube and the longitudinal length of the side plate when the molten metal filtration unit is placed on a horizontal surface and observed vertically from above, and S1 is the product of the total length L of the filtration unit 104 in Figure 2 and the width W of the side plate in Figure 3 (or Figure 4). The total contact area of ​​the legs 201 and 202 is S2, and S2 may be calculated from the dimensions of the bottom surfaces of the legs 201 and 202, or the actual contact area may be measured using ink or pressure-sensitive paper.

[0035] Although the molten metal filtration unit according to the present invention has been described above using specific embodiments, it is not intended to be limited to these embodiments. In particular, it should be noted that the molten metal filtration unit according to the present invention can be applied to any molten metal filtration unit as long as it is characterized by at least the number of legs of the side plate. For example, the filtration unit according to the present invention is not limited by the shape, length, number, etc. of the filtration tubes. The shape of the legs is not particularly limited; for example, the bottom surfaces of the legs may be sloped or may have a step. The filtration unit according to the present invention is not limited to the filtration units illustrated in the specific embodiments described above. The scope of the subject matter that can be encompassed by the present invention should be determined by the appended claims.

[0036] <Additional Embodiments Regarding the Structure of the Filter Tube> The structure of the filter tube included in the molten metal filtering unit according to the present invention is not particularly limited except as defined in the appended claims. The filter tube may satisfy specific relationships regarding the inventive shape or dimensions as exemplified in the following items [1] or [2].

[0037] [1] Additional embodiment 1 of filter tubes of molten metal filtration unit An additional example of a molten metal filtration unit includes a filter tube specified as follows: A molten metal filtration unit including: a plurality of cylindrical ceramic filter tubes arranged substantially parallel to each other, each having a substantially circular cross section perpendicular to the longitudinal direction on its outer surface and inner surface, and a pair of side plates disposed at both longitudinal ends of the plurality of ceramic filter tubes, the plurality of ceramic filter tubes having a first end on the side from which the molten metal is discharged and a second end on the other side, and at least some of the plurality of ceramic filter tubes having a longitudinal length L of a portion of the outer surface of the filter tube exposed to the molten metal １ The outer diameter of the filtration tube is D １ The longitudinal length of the part of the inner surface of the filtration tube exposed to the molten metal is L ２ The inner diameter of the filtration tube is D ２ Then, the following two relations are satisfied: (1) L１ / D １ ≧8.5 (2) L ２ / D ２ A molten metal filtration unit that satisfies all of the following requirements:

[0038] The molten metal filtration unit according to this additional embodiment may further include the following non-limiting configurations: (i) In at least some of the plurality of ceramic filter tubes, the inner diameter at the first end is larger than the inner diameter at the second end. (ii) In at least some of the plurality of ceramic filter tubes, the inner diameter at the first end is 100.5% or more and 120% or less of the inner diameter at the second end. (iii) In at least some of the plurality of ceramic filter tubes, the opening shape of the first end encompasses the opening shape of the filter tube-side end of a substantially circular through-hole provided in the side plate on the discharge side of the pair of side plates when viewed in the longitudinal direction. (iv) In the above (iii), the inner diameter of the through-hole in the side plate on the discharge side is smaller than the inner diameter of the filter tube-side end. (v) In the above (iv), the inner diameter of the end of the through hole in the side plate on the melt discharge side is 80% to 99.5% of the inner diameter of the end of the filter tube installation side. (vi) At least some of the plurality of ceramic filter tubes are fitted and fixed at each longitudinal end in a recess formed in the side plate via a packing having a shape that fits the recess. (vii) At least some of the plurality of ceramic filter tubes are formed of a porous material having a porosity of 25% to 50%.

[0039] [2] Additional embodiment 2 of filter tubes of molten metal filtration unit An additional example of a molten metal filtration unit includes a filter tube specified as follows: A molten metal filtration unit including a plurality of cylindrical ceramic filter tubes arranged substantially parallel to each other, each having a substantially circular cross section perpendicular to the longitudinal direction on its outer surface and inner surface, and a pair of side plates arranged at both longitudinal ends of the plurality of ceramic filter tubes, wherein the plurality of ceramic filter tubes have a first end on the side from which the molten metal is discharged and a second end on the other side, and at least some of the plurality of ceramic filter tubes have a longitudinal length L of a portion of the outer surface of the filter tube exposed to the molten metal. １ The outer diameter of the filtration tube is D １ The longitudinal length of the part of the inner surface of the filtration tube exposed to the molten metal is L ２ The inner diameter of the filtration tube is D ２ Then, the following two relations are satisfied: (1) L １ / D １ ≧8.5 (2) L ２ / D ２ A molten metal filtration unit that satisfies all of the above requirements.

[0040] The molten metal filtration unit according to this additional embodiment may further include the following non-limiting configurations: (i) In at least some of the plurality of ceramic filter tubes, the inner diameter at the first end is larger than the inner diameter at the second end. (ii) In (i) above, in at least some of the plurality of ceramic filter tubes, the inner diameter at the first end is 100.5% or more and 150% or less of the inner diameter at the second end. (iii) In at least some of the plurality of ceramic filter tubes, the opening shape of the first end encompasses the opening shape of the filter tube-side end of a substantially circular through-hole provided in the side plate on the discharge side of the pair of side plates when viewed in the longitudinal direction. (iv) In (iii) above, in the through-hole in the side plate on the discharge side, the inner diameter at the discharge side end is smaller than the inner diameter at the filter tube-side end. (v) In the above (iv), the inner diameter of the end of the through hole in the side plate on the melt discharge side is 70% to 99.5% of the inner diameter of the end of the filter tube installation side. (vi) At least some of the plurality of ceramic filter tubes are fitted and fixed at each longitudinal end in a recess formed in the side plate via a packing having a shape that fits the recess. (vii) At least some of the plurality of ceramic filter tubes are formed of a porous material having a porosity of 25% to 50%.

[0041] <Additional Embodiments Related to the Structure of the Side Plates> The structure of the pair of side plates included in the molten metal filtration unit according to the present invention is not particularly limited except as defined in the appended claims. These two side plates may have substantially the same external shape, being approximately rectangular parallelepiped plates, and may also satisfy specific relationships related to the inventive shapes or dimensions, as exemplified in the following items [1] or [2].

[0042] [1] Additional embodiment 1 of side plates of molten metal filtration unit An additional example of a molten metal filtration unit includes a pair of side plates specified as follows: A molten metal filtration unit including a pair of side plates and a substantially cylindrical filtration tube connected substantially perpendicularly to the pair of side plates, wherein the pair of side plates include: a first side plate having a through hole at a location connected to the filtration tube, and a second side plate the location connected to the filtration tube is closed, and when the longitudinal direction of the filtration tube is substantially horizontal and the first side plate is located to the left of the filtration tube and the second side plate is located to the right of the filtration tube, at least one of the pair of side plates has a bottom formed so that either the left side bottom edge or the right side bottom edge is positioned vertically higher than the other bottom edge.

[0043] The molten metal filtration unit according to this additional embodiment may further include the following non-limiting configurations: (i) When the longitudinal direction of the filter tube is approximately horizontal and the first side plate is located on the left side of the filter tube and the second side plate is located on the right side of the filter tube, the first side plate has a bottom portion formed so that either the left side or the right side bottom edge is positioned vertically higher than the other bottom edge, when the first side plate has a bottom portion formed so that the left side bottom edge is positioned vertically higher than the right side bottom edge, the second side plate has a bottom portion formed so that the left side bottom edge is positioned vertically higher than the right side bottom edge, or when the first side plate has a bottom portion formed so that the right side bottom edge is positioned vertically higher than the left side bottom edge, the second side plate has a bottom portion formed so that the right side bottom edge is positioned vertically higher than the left side bottom edge. (ii) When the longitudinal direction of the filtration tube is approximately horizontal, and the first side plate is located on the left side of the filtration tube, and the second side plate is located on the right side of the filtration tube, at least one of the pair of side plates has a step portion formed so that either the left side bottom edge or the right side bottom edge is positioned vertically higher than the other bottom edge. (iii) In (ii) above, when the longitudinal direction of the filtration tube is approximately horizontal, and the first side plate is located on the left side of the filtration tube, and the second side plate is located on the right side of the filtration tube, the pair of side plates have a step portion formed so that the left side bottom edge is positioned vertically higher than the right side bottom edge. (iv) In (ii) above, when the longitudinal direction of the filtration tube is approximately horizontal, the first side plate is located on the left side of the filtration tube, and the second side plate is located on the right side of the filtration tube, the step portion consists of a first bottom portion which is the lowest part, and a second bottom portion which is formed to be located vertically higher than the first bottom portion, and the ratio (W1 / W2) of the horizontal length W1 of the first bottom portion to the horizontal length W2 of the second bottom portion is 0.1 or more and 6.0 or less, where W1 and W2 are lengths in a direction parallel to the longitudinal direction of the filtration tube.(v) In (ii) above, when the longitudinal direction of the filtration tube is approximately horizontal, the first side plate is located on the left side of the filtration tube, and the second side plate is located on the right side of the filtration tube, the step portion comprises a first bottom portion which is the lowest part, and a second bottom portion which is formed to be located vertically higher than the first bottom portion, and the ratio (W1 / H2) of the horizontal length W1 of the first bottom portion to the vertical length H2 from the first bottom portion to the second bottom portion is 0.1 or more and 11 or less, where W1 is the length in a direction parallel to the longitudinal direction of the filtration tube. (vi) When the longitudinal direction of the filtration tube is approximately horizontal, and the first side plate is located on the left side of the filtration tube, and the second side plate is located on the right side of the filtration tube, at least one of the pair of side plates is formed so that either the left side bottom edge or the right side bottom edge is located vertically higher than the other bottom edge, and is provided with a bottom edge having a first bottom edge that is the lowest part and a sloped portion that connects the first bottom edge to the bottom edge that is located vertically higher. (vii) In (vi) above, when the longitudinal direction of the filtration tube is approximately horizontal, and the first side plate is located on the left side of the filtration tube, and the second side plate is located on the right side of the filtration tube, the ratio (W1' / W2') of the horizontal length W1' of the first bottom edge to the horizontal length W2' of the sloped portion is equal to or greater than 0 and equal to or less than 6.0, where W1' and W2' are lengths parallel to the longitudinal direction of the filtration tube. (viii) In (vi) above, when the longitudinal direction of the filtration tube is approximately horizontal, the first side plate is located on the left side of the filtration tube, and the second side plate is located on the right side of the filtration tube, the ratio (W1' / H2') of the horizontal length W1' of the first bottom to the vertical length H2' from the end of the inclined portion that contacts the first bottom to the other end of the inclined portion is not less than 0 and not more than 320, where W1' is the length in a direction parallel to the longitudinal direction of the filtration tube. (ix) In (viii) above, when the longitudinal direction of the filtration tube is approximately horizontal, the first side plate is located on the left side of the filtration tube, and the second side plate is located on the right side of the filtration tube, the angle θ1 between the inclined portion and the vertical direction is not less than 60° and not more than 89°.(x) In (vi) above, when the longitudinal direction of the filtration tube is approximately horizontal and the first side plate is located on the left side of the filtration tube and the second side plate is located on the right side of the filtration tube, the pair of side plates are formed so that the left bottom edge is located higher in the vertical direction than the right bottom edge, and are provided with a first bottom edge that is the lowest portion and a bottom edge that has a slope connecting the first bottom edge to the left bottom edge. (xi) In (vi) above, when the longitudinal direction of the filtration tube is approximately horizontal and the first side plate is located on the left side of the filtration tube and the second side plate is located on the right side of the filtration tube, the pair of side plates are formed so that the right bottom edge is located higher in the vertical direction than the left bottom edge, and are provided with a first bottom edge that is the lowest portion and a bottom edge that has a slope connecting the first bottom edge to the right bottom edge. (xii) A molten metal filtering device having an outlet for molten metal, wherein the molten metal filtering unit described in (ix) above has an inclined portion formed so that when the longitudinal direction of the filter tube is approximately horizontal and the first side plate is located on the left side of the filter tube and the second side plate is located on the right side of the filter tube, the right side base is positioned vertically higher than the left side base, and the first side plate is arranged so that the first side plate is in contact with the outlet, and the filtering device has a wedge-shaped protrusion on the hearth, the protrusion having an angle θ2 between a surface in contact with the molten metal filtering unit and a horizontal plane, and the sum of θ1 and θ2 satisfies 61° or more and 114° or less.

[0044] [2] Additional embodiment 2 of molten metal filtration unit An additional example of a molten metal filtration unit includes a pair of side plates specified as follows: A molten metal filtration unit including a pair of side plates and a substantially cylindrical filtration tube connected substantially perpendicularly to each of the pair of side plates, wherein the pair of side plates include a first side plate having a through hole at a location connected to the filtration tube and a second side plate the location connected to the filtration tube is closed, each side plate has at least one leg hanging down from a bottom surface of the side plate, and when the longitudinal direction of the filtration tube is substantially horizontal, the lowest vertical position of the leg of the second side plate is lower than the lowest vertical position of the leg of the first side plate.

[0045] The molten metal filtration unit according to this additional embodiment may further include the following non-limiting configurations: (i) When the longitudinal direction of the filtration tube is approximately horizontal, the ratio of the vertical length of the legs of the first side plate to the vertical length of the legs of the second side plate is 0.20 or more and less than 1.0. (ii) The total ground contact area of ​​all legs in the molten metal filtration unit is 0.015 or more and 0.075 or less relative to the total bottom area of ​​the pair of side plates. (iii) In (ii) above, the total ground contact area of ​​all legs in the molten metal filtration unit is 0.020 or more and 0.060 or less relative to the total bottom area of ​​the pair of side plates. (iv) At least two legs are provided on the first side plate and one leg is provided on the second side plate. (v) In the above (iv), at least two legs are provided near both longitudinal ends of the bottom surface of the first side plate, and one leg is provided at approximately the longitudinal center of the bottom surface of the second side plate.

[0046] The embodiments of the present invention will be specifically described with reference to the following examples, but the present invention is not limited to these examples.

[0047] Filtration units in Examples 1 to 5 and Comparative Examples 1 to 5 were prepared with the dimensions and the number of legs and filter tubes shown in Table 1. The overall length of the filtration unit differs depending on the length of the filter tubes that make up the filtration unit, and the overall length L of the filtration unit corresponds to L in FIG. 2, and the side plate width W corresponds to W in FIG. 3 or 4. In Examples 1 to 5, the first side plate had two legs and the second side plate had one leg. In Comparative Examples 1 to 5, the first side plate had two legs and the second side plate had two legs. The filtration device had a filtration chamber volume of 1.39 m ３ The filter had a base corresponding to the number of legs of the filtration unit to be installed on the hearth of the filtration chamber. ３ N ４ The refractory material used was a refractory material bonded with SiO2.

[0048] Molten metal filtration operation using a filtration unit The following steps (a) to (e) were performed as one filtration operation using the filtration units of Examples 1 to 5 and Comparative Examples 1 to 5. (a) Installation of the filtration unit The filtration unit was placed in the filtration chamber so that its legs rested on the base inside the filtration chamber. A pressing jack was used to press the filtration unit so that the first side plate of the filtration unit was in close contact with the wall surface on the tap side. The filtration unit was fixed by driving a wedge between the second side plate and the wall surface of the filtration device. (b) Preheating of the filtration device The filtration device was heated at 80°C / hour using a temperature-controlled heater installed in the filtration chamber. After the controlled temperature of the temperature-controlled heater reached 800°C, heating by the temperature-controlled heater was continued to maintain the controlled temperature at 800°C. Heating by the temperature-controlled heater continued until the temperature sensor installed in the lowest filtration tube of the filtration unit reached 700°C. (c) Filtration of molten metal 1,000 t of molten metal at 680°C to 750°C was charged into the filtration device and filtered over a period of 14 days. (d) Cooling of filtration device The filtration device was left standing until the temperature sensor installed in the lowest filtration tube in the filtration unit reached room temperature. (e) Removal of filtration unit The wedge between the second side plate and the wall of the filtration device was removed, and the filtration unit was removed from the filtration device.

[0049] Evaluation of the Placement Stability of the Filtration Unit The placement stability of the filtration unit was evaluated by inserting a feeler gauge between the legs of the filtration unit and the base. After step (a) of the filtration operation and before step (b), a feeler gauge was inserted between each leg and the base of the filtration chamber. The placement stability of the filtration unit was evaluated as follows based on the value of the feeler gauge inserted into the largest gap between each leg and the base of the filtration chamber. A: Less than 0.5 mm (the 0.5 mm feeler gauge did not fit into any of the legs). B: 0.5 mm or more but less than 2.0 mm (the 0.5 mm feeler gauge fit into one or more legs, but the 2.0 mm feeler gauge did not fit into one or more legs). C: 2.0 mm or more (the 2.0 mm feeler gauge fit into one or more legs).

[0050] The evaluation of the placement stability of the filtration unit was performed after the filtration unit was installed in the filtration chamber for the first time (i.e., after step (a) of the first filtration operation), after the 15th filtration operation (i.e., after step (a) of the 16th filtration operation), and after the 30th filtration operation (i.e., after step (a) of the 31st filtration operation).

[0051] Evaluation of Preheating Ability of Filtration Device In order to eliminate the influence of aging deterioration of the filtration device, the preheating ability of the filtration device was evaluated by measuring the change in temperature over time of the filtration unit in step (b) of the first filtration operation. Specifically, the time until the temperature sensor installed in the lowest filtration tube of the filtration unit reached 500°C was measured in step (b) of the first filtration operation. The change in temperature over time controlled by the temperature-controlled heater and the change in temperature over time of the filtration units of Example 1 and Comparative Example 1 are shown in Figure 5. For the filtration units of Examples 1 to 5 and Comparative Examples 1 to 5, the preheating ability of the filtration device was evaluated based on the change in temperature over time as follows: A: The time until 500°C was reached was less than 80 hours. B: The time until 500°C was reached was 80 hours or more but less than 85 hours. C: The time until 500°C was reached was 85 hours or more.

[0052] The dimensions of the filtration unit and the evaluation results are shown in Table 1.

[0053] According to the filtration unit of the present invention, by optimizing the relationship between the numbers of legs provided on the two side plates, stable placement within an aging filtration chamber and improved preheating efficiency of the filtration device are possible. Therefore, the filtration unit of the present invention can facilitate preparation for filtration of molten metal and, in turn, improves the efficiency of filtering impurities from molten metal such as aluminum. Therefore, the filtration unit of the present invention can be used in various industries where such filtering work is required, such as the metal industry and the steel industry.

[0054] 101: Filtration device 102: Inlet port 103: Filtration chamber 104: Filtration unit 105: Outlet chamber 106, 110: Outlet port 107: First side plate 108: Second side plate 109: Filtration tube 201: Leg of first side plate 202: Leg of second side plate

Claims

1. A molten metal filtration unit comprising a pair of side plates and a substantially cylindrical filtration tube connected to each of the pair of side plates substantially perpendicularly, wherein the pair of side plates includes a first side plate having a through hole at a location connected to the filtration tube and a second side plate having a closed location connected to the filtration tube, each side plate includes legs vertically provided from the bottom surface of the side plate, and the number of legs provided on the first side plate is at least one more than the number of legs provided on the second side plate. The molten metal filtration unit.

2. The molten metal filtration unit according to claim 1, wherein the first side plate is provided with two legs and the second side plate is provided with one leg.

3. The molten metal filtration unit according to claim 1, wherein two legs are provided near both longitudinal ends of the bottom surface of the first side plate and one leg is provided at a substantially central portion in the longitudinal direction of the bottom surface of the second side plate.

4. When the molten metal filtration unit is placed on a horizontal plane and observed from directly above, the area of the molten metal filtration unit represented by the product of the length of the molten metal filtration unit in the longitudinal direction of the filtration tube and the longitudinal length of the side plate is defined as S1, and the total area of the grounding areas of all the legs of the molten metal filtration unit is defined as S2. The molten metal filtration unit according to claim 1, wherein the area ratio S2 / S1 is 0.0020 or more and 0.015 or less.

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