JP5695461B2 - Al scrap refining method - Google Patents

Description

  In particular, the present invention removes silicon (hereinafter referred to as “Si”) as an impurity element from aluminum (hereinafter referred to as “Al”) scrap at a high rate, and Al crystallized material (hereinafter referred to as “primary crystal”). Is also related to a method for refining Al scrap that has a high recovery rate (that is, obtains an Al refined body in a high volume).

  In recent years, the production amount of clad materials and the like has increased, and the amount of scrap accompanying therewith has increased. However, since the clad material is made by stacking several kinds of Al alloys having different compositions, it is difficult to simply recycle the scrap to the product. Therefore, a technique for refining the scrap (Al scrap) and creating a reusable Al material from which impurity elements are removed is desired.

  Several techniques have been proposed as a technique that meets the above-mentioned demand.

  For example, in Patent Document 1, an Al alloy scrap molten metal containing 0.5 to 10% by mass of Si is contained in a container, and almost the entire area of the molten metal is 20 ° C. up to a temperature below the liquidus of the molten metal and above the solidus. The primary crystal is generated by cooling at a speed of / min or less, and then the compaction plate is lowered from the upper part of the container to form an aggregate of Al crystallized product (primary crystal) and a concentrated liquid phase, and then Disclosed is an Al scrap refining method for separating and recovering primary crystals compacted from the concentrated liquid phase by applying a load corresponding to a pressure of 2 to 15 MPa to the bottom surface of the compacted plates. ing. Also disclosed is a method of reusing Al scrap, characterized in that the recovered primary crystal and / or concentrated liquid phase is mixed with other raw material Al molten metal.

    In Patent Document 2, an Al scrap molten metal is accommodated in a container, the Al scrap molten metal is cooled to a temperature below the liquidus and above the solidus, and then the press plate is lowered from the upper part of the container. And forming an aggregate of Al crystallized product (primary crystal) and a concentrated liquid phase, and then applying a predetermined pressure to the aggregate of primary crystal by a compaction plate, Separation into an aggregate and a concentrated liquid phase, raising the pressing plate above the concentrated liquid phase, and then repeating the above cooling, pressure application and separation steps on the concentrated liquid phase An Al scrap refining method is disclosed in which an Al refined body in which the primary crystal aggregates are stacked is recovered.

Japanese Patent Application Laid-Open No. 07-54061 JP 2010-132984 A

  However, the techniques disclosed in Patent Documents 1 and 2 have the following problems.

  That is, the technique relating to the Al scrap refining method described in Patent Document 1 includes Si removal rate (hereinafter also referred to as “Si removal rate”) and primary crystal recovery rate (hereinafter also referred to as “Al recovery rate”). To obtain an Al refined body satisfying both a high Si removal rate and a high Al recovery rate {hereinafter referred to as “a high Si removal rate Al refined body (compressed primary crystal aggregate) It can't be said “to obtain with volume (high Al recovery rate)”. Therefore, for example, when the Al scrap is refined under conditions that provide a high Si removal rate, it takes a very long time to obtain a high volume Al refined body from the Al scrap molten metal, resulting in poor productivity.

  Moreover, the technique regarding the refinement | purification method of Al scrap of patent document 2 eliminates the problem of the technique disclosed by the said patent document 1, Al refined body (pressed primary crystal of high Si removal rate from Al scrap) In that it can be obtained in a high volume (high Al recovery rate). However, in order to obtain a high volume Al refined body, the number of times of pressing is required three times, and there is still difficulty in terms of production efficiency.

  An object of the present invention is to provide an Al scrap that can produce an Al refined body (pressed primary crystal aggregate) having a predetermined high Si removal rate from Al scrap with a high volume (high Al recovery rate) and high efficiency. It is to provide a purification method.

In order to achieve this object, the method for refining Al scrap according to the first invention comprises:
In the method of refining the Al scrap molten metal accommodated in the container,
The Al scrap molten metal contains 0.5 to 3% by mass of Si and 2% by mass or less in total of at least one element selected from the group consisting of Fe, Cu, Mn, Mg, Cr, Zn, and Ti. Is what
Primary crystal generation that generates Al crystallized material (hereinafter referred to as “primary crystal”) in the Al scrap molten metal by cooling the Al scrap molten metal in the vessel to a temperature below the liquidus and above the solidus. Process,
Lowering the compaction plate provided with the liquid phase discharge holes from the upper part of the container containing the Al scrap molten metal containing the primary crystal generated in the primary crystal generation step, the primary crystal aggregate and the concentrated liquid phase And compressing the primary crystal aggregate by applying pressure to the primary crystal aggregate by the pressing plate, and obtaining a concentrated liquid phase.
For discharging the liquid phase below the pressure loading portion and the compaction plate other than the liquid phase discharge hole to the Al scrap molten metal containing the primary crystal generated in the primary crystal generation step. The pressing plate is lowered so that there is a pressure-unloaded portion where no pressure is applied ,
The pressure is 4 MPa or more and 7 MPa or less, the pressure application time is 10 minutes or more, and the area ratio of the pressure-unloaded portion with respect to the entire area of the molten metal surface in a state where the pressing plate is not lowered is 5 It is the refinement | purification method of Al scrap characterized by being -40% .

The method for refining Al scrap according to the second invention is the method for refining Al scrap according to the first invention ,
The container has a bottomed cylindrical shape,
The pressing plate has a disk shape in which at least one flat portion is provided on the outer surface.

The method for refining Al scrap according to the third invention is the method for refining Al scrap according to the first or second invention ,
Stirring cooling is used in the primary crystal generation step of generating primary crystals in the Al scrap molten metal.

As described above, the present invention
In the method of refining the Al scrap molten metal accommodated in the container,
The Al scrap molten metal contains 0.5 to 3% by mass of Si and 2% by mass or less in total of at least one element selected from the group consisting of Fe, Cu, Mn, Mg, Cr, Zn, and Ti. Is what
Primary crystal generation that generates Al crystallized material (hereinafter referred to as “primary crystal”) in the Al scrap molten metal by cooling the Al scrap molten metal in the vessel to a temperature below the liquidus and above the solidus. Process,
Lowering the compaction plate provided with the liquid phase discharge holes from the upper part of the container containing the Al scrap molten metal containing the primary crystal generated in the primary crystal generation step, the primary crystal aggregate and the concentrated liquid phase And compressing the primary crystal aggregate by applying pressure to the primary crystal aggregate by the pressing plate, and obtaining a concentrated liquid phase.
For discharging the liquid phase below the pressure loading portion and the compaction plate other than the liquid phase discharge hole to the Al scrap molten metal containing the primary crystal generated in the primary crystal generation step. The pressing plate is lowered so that there is a pressure-unloaded portion where no pressure is applied.

  Therefore, according to the present invention, in the squeezing step, the liquid phase can be actively released from the pressure unloaded portion side, so that the discharge of the concentrated liquid phase is promoted while the degree of squeezing is small, and Al scrap Thus, an Al refined body having a predetermined high Si removal rate (compressed primary crystal aggregate) can be produced in a high volume (high Al recovery rate) and with high efficiency.

It is a schematic diagram for demonstrating the process of the refinement | purification method of the Al scrap of Embodiment 1 of this invention in time series. FIG. 2 is a schematic equilibrium diagram of Al—Si when the process shown in FIG. 1 is used. It is a schematic explanatory drawing for demonstrating in detail the process shown in FIG.1 (c). It is AA cross-sectional schematic diagram of Al scrap molten metal containing the primary crystal shown in FIG.3 (b). It is explanatory drawing for demonstrating the relationship between the thickness of the collection | recovery solid phase (Al refinement | purification body) and Si removal rate in the example of this invention and a comparative example, respectively. It is a schematic explanatory drawing for demonstrating in detail the characteristic process in the refinement | purification method of the Al scrap of Embodiment 2 of this invention. It is a BB cross-sectional schematic diagram of Al scrap molten metal containing the primary crystal shown in FIG.6 (b).

(Configuration of Al scrap refining method according to the present invention)
The method for refining Al scrap according to the present invention is as follows:
In the method of refining the Al scrap molten metal accommodated in the container,
The Al scrap molten metal contains 0.5 to 3% by mass of Si and 2% by mass or less in total of at least one element selected from the group consisting of Fe, Cu, Mn, Mg, Cr, Zn, and Ti. Is what
Primary crystal generation that generates Al crystallized material (hereinafter referred to as “primary crystal”) in the Al scrap molten metal by cooling the Al scrap molten metal in the vessel to a temperature below the liquidus and above the solidus. Process,
Lowering the compaction plate provided with the liquid phase discharge holes from the upper part of the container containing the Al scrap molten metal containing the primary crystal generated in the primary crystal generation step, the primary crystal aggregate and the concentrated liquid phase And compressing the primary crystal aggregate by applying pressure to the primary crystal aggregate by the pressing plate, and obtaining a concentrated liquid phase.
For discharging the liquid phase below the pressure loading portion and the compaction plate other than the liquid phase discharge hole to the Al scrap molten metal containing the primary crystal generated in the primary crystal generation step. The pressing plate is lowered so that there is a pressure-unloaded portion where no pressure is applied.

Because of the configuration as described above, the present invention
In the squeezing step, the liquid phase can be actively released from the pressure-unloaded portion side, so that the discharge of the concentrated liquid phase is promoted while the degree of squeezing is small, and a predetermined high Si removal rate from the Al scrap. Al refined body (compressed primary crystal aggregate) can be produced with high volume (high Al recovery rate) and high efficiency.
Si removal rate = (Si concentration of initial Al scrap molten metal−Si concentration of pressed primary crystal aggregate) / Si concentration of initial Al scrap molten metal × 100 (1)
Al recovery rate = pressed primary crystal aggregate volume / initial Al scrap molten metal volume × 100
(2)

  The reason for reaching the above configuration will be described below.

  The present inventors have made it possible to obtain a high volume (high Al recovery rate) of an Al refined body (compressed primary crystal aggregate) having a predetermined high Si removal rate (for example, about 50 to 60%) from Al scrap. In addition, intensive research was conducted as to whether it could be produced with high efficiency (for example, one press).

  As a result, by pressing the Al scrap molten metal containing the primary crystal generated in the primary crystal generation process using the above-described compaction plate, the liquid phase can be actively released from the pressure-unloaded portion side. Therefore, the discharge of the concentrated liquid phase is promoted while the degree of pressing is small, and the Al purified body (pressed primary crystal aggregate) having the above-mentioned Si removal rate from Al scrap has a high volume (for example, a diameter of 100 mm − It has been found that it can be produced by a single pressing with a thickness of 200-300 mm.

  Hereinafter, an embodiment of the Al scrap refining method of the present invention will be described with reference to the drawings.

(Embodiment 1)
FIG. 1 is a schematic diagram for chronologically explaining the process of the Al scrap refining method according to Embodiment 1 of the present invention. FIG. 1 (a) shows a state in which an Al scrap molten metal 2 is accommodated in a container 1. FIG. 4B is a primary crystal generation process diagram in which the Al scrap molten metal 2 is cooled to a temperature below the liquidus and above the solidus to generate the primary crystal 3a in the Al scrap molten metal 2. FIG. The stamper 4 is lowered from the upper part of the container 1 in which the Al scrap molten metal 2 containing the primary crystal 3a is accommodated, and the pressing plate 4a provided at the lower end of the stamper 4 to the upper layer part of the Al scrap molten metal 2 containing the primary crystal 3a. FIG. 8D is a diagram showing a state in which a pressure load part a to which pressure is applied and a pressure unload part a to which pressure is not applied are generated by bringing the stamper 4 into contact with each other. FIG. And concentrated liquid phase 6a In addition, by applying pressure to the aggregate of the primary crystal 3a by the compaction plate 4a, the compressed primary crystal aggregate (hereinafter also referred to as “recovered solid phase 5a”) and the concentrated liquid phase 6a FIG. In addition, after FIG.1 (d), there exists a process which raises the stamper 4 and takes out the pressing board 4a out of the container 1, but illustration is abbreviate | omitted here.

  FIG. 2 is a schematic equilibrium diagram of Al—Si when the process shown in FIG. 1 is used.

  Below, the process of the refinement | purification method of the Al scrap of this embodiment is demonstrated in detail in time series using FIGS. 1-4.

In FIG. 1A, the container 1 has a cylindrical shape with a bottom having a cylindrical portion 1b (for details, see FIG. 3 to be described later) having an inner diameter of 100 mm and a height from the bottom portion 1a (for details, see FIG. 3 to be described later). It is made of graphite, and a heater (not shown) and a cooling device (not shown) are disposed around the container 1. Further, in this container 1, a 10 kg alloy (Al scrap) made of a component of Al-1.5% by mass Si-0.1% by mass Fe (this composition is indicated by an initial composition C ₀ (see FIG. 2)). ) Is melted and accommodated (the height of the Al scrap molten metal 2 is indicated by h ₀ ). The height _{h 0} of the Al scrap melt 2 is 400 mm.

In FIG. 1B, while stirring the Al scrap molten metal 2, while adjusting the heater and the cooling device to a temperature T ₁ (for example, 640 ° C.) below the liquidus line and above the solidus line shown in FIG. By cooling, the primary crystal 3a (primary crystal concentration: C _s1 (see FIG. 2)) is generated in the Al scrap molten metal 2.

In FIG. 1 (c), the temperature T ₁ (herein, this temperature is referred to as pressing temperature) is externally attached from the upper part of the container 1 containing the Al scrap molten metal 2 containing the primary crystal 3 a to the tip of the support part 4 b. The stamper 4 having an iron compaction plate 4a having a diameter of 90 mm (refer to the description of FIG. 3 to be described later for the detailed shape) is slowly lowered to the compaction plate 4a to the upper layer portion of the Al scrap molten metal 2 containing the primary crystal 3a. Are caused to generate a pressure load part a in which pressure is applied to the Al scrap molten metal 2 containing the primary crystal 3a and a pressure unload part a in which no pressure is applied (for the detailed shape, see FIG. 4 to be described later). reference).

In FIG. 1 (d), the stamper 4 is further lowered from the state shown in FIG. 1 (c) to separate the primary crystal 3a aggregate into the concentrated liquid phase 6a, and the primary crystal 3a is separated by the compaction plate 4a. By applying pressure (for example, 6.5 MPa) to the aggregate as a pressure application time, for example, for 10 minutes, the primary crystal aggregate that has been squeezed (hereinafter also referred to as “recovered solid phase 5a” or an Al refined body) And concentrated liquid phase 6a {liquid phase concentration: C _L1 (see FIG. 2)}. Thereby, the recovery solid phase 5a (Al refined body) of the predetermined high Si removal rate of high volume (thickness h1) is obtained by _one pressing.

FIG. 3 is a schematic explanatory diagram for explaining in detail the process shown in FIG. In FIG. 3, (a) is a shape of the pressing plate 4a as viewed from above, (b) is a pressure load portion a where pressure is applied to the Al scrap molten metal 2 containing the primary crystal 3a as described above, and pressure is applied. FIG. 3 schematically shows a liquid phase flow {arrow (→)} in a longitudinal section when a pressure-unloaded portion a that is not generated is generated. Further, one flat portion 4e is provided on the right side of the pressing plate 4a having an outer diameter of 90 mm toward the paper surface. Thus, it exhibits _{L 1} of the soil compacting plate 4a is 75 mm, the maximum gap _{L 2} is 20mm disc-shaped with the inner wall of the flat portion 4e and the container 1 of the cylindrical portion 1b of the soil compacting plate 4a. Further, a gap of 5 mm exists between the left outer surface 4d and the inner wall of the cylindrical portion 1b of the container 1 with respect to the paper surface of the pressing plate 4a. In addition, the compaction plate 4a is provided with ten liquid phase discharge holes 4c having a diameter of 7 mm. The gap of 5 mm is a play for preventing the pressing plate 4a from being damaged when the stamper 4 is moved up and down. The term “liquid phase below the pressing plate 4a is used as a liquid phase discharge hole” in the present invention. It is not intended to actively discharge from other than 4c.

  FIG. 4 is a schematic cross-sectional view of the AA cross section of the Al scrap molten metal 2 containing the primary crystal 3a shown in FIG. 3 (b), and the Al scrap molten metal including the disk-shaped pressing plate 4a as described above includes the primary crystal 3a. 2 schematically shows the detailed shape of the pressure load part a when the upper layer part 2 is contacted and the pressure unload part a where no pressure is applied. When the pressing plate 4a is lowered in such a pressure state, the liquid phase is discharged directly through the liquid phase discharge hole 4c as shown in FIG. The liquid phase below 4a moves positively toward the pressure-unloaded portion (a) side and is discharged in a large amount. As a result, the discharge of the concentrated liquid phase is promoted even though the degree of squeezing is small, and a high volume (high Al recovery) of Al refined body (compressed primary crystal aggregate) having a predetermined high Si removal rate from Al scrap. Rate) and high efficiency.

In this embodiment, although the example using the compression plate 4a of a shape as shown in FIG. 3 was demonstrated, it is not necessarily limited to this. That is, in order to produce an Al refined body (compressed primary crystal aggregate) that satisfies a predetermined high Si removal rate and a predetermined high volume (high Al recovery rate) with high efficiency,
A liquid provided in the compaction plate with a pressure loading portion to which pressure is applied by the compaction plate and a liquid phase below the compaction plate with respect to the Al scrap molten metal containing the primary crystal generated in the primary crystal generation step What is necessary is just to be comprised so that the said compression plate may be lowered | hung so that the pressure unloading part which is not loaded with the pressure for discharging | emitting from other than a phase discharge hole may exist.

  In addition, in this embodiment, as shown in FIG. 3, although the example which provided one plane part 4e on the right side toward the paper surface of the pressing board 4a was demonstrated, it is not necessarily limited to this, The cross section perpendicular to the descending direction of the pressing plate (hereinafter referred to as “transverse section”) is smaller than the shape surrounded by the inner peripheral line of the container, and an area of a predetermined ratio with respect to the area of the shape Can be configured to have a disk shape in which a plurality of flat portions are provided on the outer side surface of the compression plate (this example is described in Embodiment 2 below). Explain in detail). Further, the shape provided on the outer side surface of the pressing plate 4a is not necessarily limited to the flat portion. Moreover, although it depends on the shape and size of the container and the compaction plate, the area ratio of the pressure-unloaded portion with respect to the entire area of the molten metal surface (the state where the compaction plate is not lowered) should be about 5 to 40%. it can.

  Further, the compaction plate is lowered to separate the primary crystal aggregate and the concentrated liquid phase, and by applying pressure to the primary crystal aggregate by the compaction plate, the compressed primary crystal In the pressing step for obtaining the aggregate and the concentrated liquid phase, the pressure is preferably 4 MPa or more and 7 MPa or less, and the pressure application time is preferably 10 minutes or more. This is because if the pressure is less than 4 MPa, a sufficient Si removal rate cannot be obtained, and if it exceeds 7 MPa, there is no significant change in the Si removal rate. In addition, regarding the pressure application time, the liquid phase cannot be sufficiently discharged from the primary crystal aggregate to be pressed in 5 minutes, and the effect of liquid phase discharge is almost constant in 8 minutes. Ten minutes or more is appropriate.

  In addition, in the step of generating primary crystals in the Al scrap molten metal, stirring and cooling rather than cooling the liquid in a stationary state applies pressure to the primary crystal aggregates, and the primary crystal aggregates that have been squeezed And the concentrated liquid phase are more preferable because the path for discharging the liquid phase portion from the pressed primary crystal aggregate is not complicated. This is because when the liquid is cooled in a stationary state, the shape of the generated primary crystal becomes dendrite, but when the liquid is stirred and cooled, the shape of the generated primary crystal is rounded.

In the Al scrap refining method according to the present invention shown in FIGS. 1 to 4 described above, the recovered solid phase 5a (Al The thickness h ₁ of the purified product) is the value shown in Table 1 below {Test No. 1 to 5 (invention example)}. Further, for comparison, a pressing plate 4a having no flat portion 4e (that is, a pressing plate having a circular cross section as disclosed in Patent Document 2; a liquid phase made of iron having an outer diameter of 90 mm and a diameter of 7 mm). The thickness h ₁ of the recovered solid phase 5a (Al refined body) is expressed by each value shown in Table 1 below (test No. 1) using 20 discharge holes 4c). 6 to 20 (comparative example)}. As a result, test no. 1 and 2, the thickness h ₁ of the recovered solid phase 5a (Al purified product) was 210 mm, the Si removal rates were 62.1% and 61.7%, respectively, and test Nos. 3, the thickness h ₁ of the recovered solid phase 5a (Al purified product) was 205 mm, the Si removal rate was 64.8%, and the test No. 3 4, the thickness h ₁ of the recovered solid phase 5a (Al purified product) is 300 mm, the Si removal rate is 53.0%, and test No. 4 is obtained. 5, the thickness h ₁ of the recovered solid phase 5a (Al purified product) was 300 mm, and the Si removal rate was 50.1% (see Table 1 and FIG. 5 below). However, in the comparative example, the Si removal rate exceeds 50%, and the thickness h ₁ of the recovered solid phase 5a (Al purified product) is 150 mm or less (test Nos. 6 to 16 in Table 1 below). , 18, 20 and FIG. 5). In the comparative example, when the thickness h ₁ of the recovered solid phase 5a (Al refined body) is relatively thick at 190 mm and 210 mm, only Si removal rates of 40.7% and 39.2% are obtained, respectively. (See Test Nos. 17 and 19 and Table 5 in Table 1 below). As described above, by using the Al scrap refining method of the present invention, the recovered solid phase 5a (Al refined body) having a predetermined high Si removal rate (for example, 50% or more) from Al scrap for the first time has a high volume (for example, (Diameter: 100 mm—thickness: 200 to 300 mm) and high efficiency (for example, one press).

(Embodiment 2)
In the method for refining Al scrap according to the present invention shown in FIGS.
When the inner diameter of the cylindrical portion 1b of the container 1 is 1000 mm, the pressing plate 4a is designed so as to have the same ratio as in the first embodiment (0.2 = longest gap L ₂ / outer diameter of the pressing plate 4a). The following problems occur. That is, the longest gap L ₂ becomes too large, in the expression step, the primary crystal 3a resulting in a large amount of relief over the compacted plate 4a press together with the liquid phase. Therefore, another Al scrap refining method according to the present invention that can cope with such a case is proposed. Details will be described below with reference to FIGS. In the present embodiment, the same components as those of the purification apparatus used in the first embodiment are given the same reference numerals, detailed description thereof is omitted, and only different portions are described in detail.

FIG. 6 is a schematic explanatory view for explaining in detail the characteristic steps in the Al scrap refining method of Embodiment 2 of the present invention, wherein (a) is a shape of the pressing plate 4a viewed from above, (b ) Is a pressure load section C (for details, refer to FIG. 7 to be described later) where pressure is applied to the Al scrap molten metal 2 containing the primary crystal 3a and a pressure unload section D (for details, refer to FIG. 7 for details). The flow of the liquid phase {arrow (→)} when generated is schematically shown in a longitudinal section. The pressing plate used in the second embodiment is provided with one flat portion 4e and 4f on the right side and the left side of the pressing plate 4a having an outer diameter of 990 mm. Thus, _{L 3} of the soil compacting plate 4a exhibits 900 mm, flat portions 4e of the soil compacting plate 4a, the longest gap _{L 4} is 50mm in each disc-shaped and 4f and the container 1 of the inner wall of the cylindrical portion 1b. Further, a gap of 5 mm exists between the upper and lower outer surfaces 4d toward the paper surface of the pressing plate 4a and the inner wall of the cylindrical portion 1b of the container 1 as in the first embodiment. In addition, the pressing plate 4a is provided with 1000 liquid phase discharge holes 4c having a diameter of 7 mm. The gap of 5 mm is a play for preventing the presser plate 4a from being damaged when the stamper 4 is moved up and down, as in the first embodiment, and is referred to as “below the press plate 4a” in the present invention. It is not intended to positively discharge the liquid phase from other than the liquid phase discharge hole 4c.

FIG. 7 is a schematic BB cross-sectional view of the Al scrap molten metal 2 containing the primary crystal 3a shown in FIG. 6 (b), and the pressing plate 4a having a disk shape having the flat portions 4e and 4f as described above is provided. The detailed shape of the pressure load part C when the upper part of the Al scrap molten metal 2 including the primary crystal 3a is contacted and the pressure unload part D where no pressure is applied is schematically shown. When the pressing plate 4a is lowered in such a pressure state, as shown in FIG. 6B, the liquid phase is discharged directly through the liquid phase discharge hole 4c, and the pressing plate is pressed. The liquid phase below 4a is positively moved toward the left and right pressure-unloaded portions d side and is moved and discharged in large quantities. However, when performing such pressing, since L ₄ (for example, 50 mm) of a predetermined dimension is satisfied and two places are provided, the liquid phase below the compression plate 4a is left and right pressure-unloaded. The primary crystal 3a does not escape to a large amount above the compaction plate 4a together with the liquid phase. Accordingly, even when the container 1 is squeezed using a large container 1 having an inner diameter of 1000 mm, the discharge of the concentrated liquid phase is promoted while the degree of squeezing is small, and Al having a predetermined high Si removal rate from Al scrap. A refined body (compressed primary crystal aggregate) can be produced in a higher volume (high Al recovery rate) and with higher efficiency.

  In addition, in Embodiment 1, 2, although the internal diameter of the cylindrical part 1b of the container 1 demonstrated the example which is 100 mm and 1000 mm, it is not necessarily limited to this. However, when the inner diameter is less than 100 mm, the production amount of the Al refined body (pressed primary crystal aggregate) is small and the productivity is poor. On the other hand, if the inner diameter exceeds 1000 mm, the path moving toward the pressure-unloaded portion of the liquid phase below the compression plate 4a becomes too long, and a sufficient Si removal rate cannot be obtained. Accordingly, the inner diameter of the cylindrical portion 1b of the container 1 is suitably 100 mm to 1000 mm. In the first and second embodiments, the example in which the cross section of the container 1 is circular has been described. However, the present invention is not necessarily limited thereto, and various cross sectional shapes (for example, rectangles) may be employed. It is.

  Moreover, the depth of the Al scrap molten metal 2 accommodated in the container 1 is the technology of the present invention that “the liquid phase below the pressing plate is discharged from other than the liquid phase discharge holes provided in the pressing plate”. In light of the idea and taking into account the point of securing the superiority of the discharge amount of the liquid phase from the pressure-unloaded portion side as compared with the discharge amount of the liquid phase from the liquid phase discharge hole, for example, When the cross section of the container 1 is circular, it is desirable that the inner diameter of the container 1 is twice or more.

Further, as in the first and second embodiments, for example, when the cross section of the container 1 is circular and the inner diameter of the cylindrical portion 1b of the container 1 is 100 mm to 1000 mm, the above-described L ₂ is 0.2 times the inner diameter or more and 50 mm. It is preferable to satisfy the following. This is because when L ₂ is less than 0.2 times the inner diameter, the liquid phase discharge amount from the pressure-unloaded portion side described above is superior to the liquid phase discharge amount from the liquid phase discharge hole. This is because it cannot be secured. Further, the reason why L _{2 is set} to 50 mm or less is to prevent the primary crystal 3a from escaping above the compaction plate 4a together with the liquid phase in the pressing step.

  Moreover, in the said Embodiment 1, 2, although the example whose component of Al scrap molten metal 2 was Al-1.5 mass% Si-0.1 mass% Fe was demonstrated, it is not necessarily limited to this. The Al scrap molten metal contains 0.5 to 3% by mass of Si and 2% by mass or less in total of at least one element selected from the group consisting of Fe, Cu, Mn, Mg, Cr, Zn, and Ti. The technical idea of the present invention can be applied to the above.

DESCRIPTION OF SYMBOLS 1 Container 1a Bottom part 1b Cylindrical part 2 Al scrap molten metal 3a Primary crystal 4 Stamper 4a Compaction board 4b Support part 4c Liquid phase discharge | emission hole 4d Outer side surface 4e, 4f Planar part 5a Recovery solid phase 6a Concentrated liquid phase

Claims (3)

In the method of refining the Al scrap molten metal accommodated in the container,
The Al scrap molten metal contains 0.5 to 3% by mass of Si and 2% by mass or less in total of at least one element selected from the group consisting of Fe, Cu, Mn, Mg, Cr, Zn, and Ti. Is what
Primary crystal generation that generates Al crystallized material (hereinafter referred to as “primary crystal”) in the Al scrap molten metal by cooling the Al scrap molten metal in the vessel to a temperature below the liquidus and above the solidus. Process,
Lowering the compaction plate provided with the liquid phase discharge holes from the upper part of the container containing the Al scrap molten metal containing the primary crystal generated in the primary crystal generation step, the primary crystal aggregate and the concentrated liquid phase And compressing the primary crystal aggregate by applying pressure to the primary crystal aggregate by the pressing plate, and obtaining a concentrated liquid phase.
For discharging the liquid phase below the pressure loading portion and the compaction plate other than the liquid phase discharge hole to the Al scrap molten metal containing the primary crystal generated in the primary crystal generation step. The pressing plate is lowered so that there is a pressure-unloaded portion where no pressure is applied ,
The pressure is 4 MPa or more and 7 MPa or less, the pressure application time is 10 minutes or more, and the area ratio of the pressure-unloaded portion with respect to the entire area of the molten metal surface in a state where the pressing plate is not lowered is 5 A method for refining Al scrap, characterized in that it is -40% . The container has a bottomed cylindrical shape,
2. The method for refining Al scrap according to claim 1, wherein the pressing plate has a disk shape in which at least one flat portion is provided on an outer surface. 3. The method for purifying Al scrap according to claim 1 or 2 , wherein stirring cooling is used in the primary crystal generation step of generating primary crystals in the Al scrap molten metal.

Images