Method for producing aluminum raw material, method for producing aluminum material, and compression device

Abstract

A method for producing an aluminum raw material according to one embodiment of the present disclosure comprises: a step for raising the temperature of a lump of aluminum containing impurities to achieve a semi-molten state; a step for pressing the heated lump by means of a pressing member; and a step for recovering, as an aluminum raw material, a solid phase from which a liquid phase containing at least a portion of the impurities is separated as a result of pressing the lump. In the pressing step, a heat insulating member is disposed between the pressing member and the lump.

Description

Method for producing aluminum raw material, method for producing aluminum material, and pressing device

[0001] The present disclosure relates to a method for producing an aluminum raw material, a method for producing an aluminum material, and a pressing device.

[0002] Currently, in view of resource depletion, recycling of various materials is progressing, and recycling of metals, which are consumed in large quantities, has been carried out for some time. A method is known in which unnecessary elements are removed from recycled aluminum to produce a material containing desired elements (Japanese Patent Laid-Open Publication No. 5-098363).

[0003] Japanese Patent Application Publication No. 5-098363

[0004] In Patent Document 1, an aluminum block containing elements (impurities) such as Cu to be removed is heated to a solid-liquid coexistence temperature range and deformed, forming a central region mainly made of solid phase (solid phase) and a peripheral region mainly made of liquid phase (liquid phase) containing some of the impurities, and the solidified liquid phase is cut and separated to obtain a solid phase with reduced impurities. This method is said to be able to reduce the impurity concentration in the solid phase by causing the impurities to flow out into the liquid phase, but there is a need for an easier and more thorough method of removing impurities.

[0005] In view of the above circumstances, an object of the present disclosure is to provide a method for producing aluminum raw material that can easily and sufficiently remove impurities from aluminum chunks.

[0006] The present inventors have discovered that, unlike the case of compressing aluminum crystals in a molten metal after heating, when a mass of aluminum in a semi-molten state is compressed in air, the temperature of the mass drops rapidly due to heat removal from the pressing member pressing the mass, and this temperature drop reduces the effectiveness of removing impurities from the mass. The present inventors have thoroughly investigated means for suppressing this heat removal and have completed the invention of the present disclosure.

[0007] A method for producing an aluminum raw material according to one aspect of the present disclosure that solves the above problem includes the steps of heating an aluminum lump containing impurities so that it reaches a semi-molten state, pressing the heated lump with a pressing member, and recovering a solid phase, which is separated from a liquid phase containing at least a portion of the impurities by pressing the lump, as an aluminum raw material, and in the pressing step, an insulating member is arranged between the pressing member and the lump.

[0008] The method for producing an aluminum raw material according to the present disclosure can easily and sufficiently remove impurities from an aluminum lump.

[0009] Fig. 1 is a schematic front cross-sectional view showing a compression device according to one embodiment of the present disclosure. Fig. 2 is a graph showing the temperature change of a mass in an example of the present disclosure. Fig. 3 is a graph showing the temperature change of another mass in an example of the present disclosure.

[0010] [Description of Embodiments of the Present Disclosure] First, embodiments of the present disclosure will be listed and described.

[0011] (1) A method for producing an aluminum raw material according to one aspect of the present disclosure includes the steps of heating an aluminum lump containing impurities to a semi-molten state, pressing the heated lump with a pressing member, and recovering a solid phase, which is separated from a liquid phase containing at least a portion of the impurities by pressing the lump, as an aluminum raw material, wherein an insulating member is disposed between the pressing member and the lump during the pressing step.

[0012] This aluminum raw material manufacturing method involves heating an aluminum block containing impurities to a semi-molten state and then pressing the heated block, thereby easily separating the block into a liquid phase containing at least some of the impurities and a solid phase with reduced impurities. The pressing member that presses the block has a heat insulating member disposed between it and the block, allowing the block to be pressed while suppressing a temperature drop of the block due to contact with the pressing member. This prevents a reduction in the impurity discharge effect in the block (the effect of the impurities flowing into the liquid phase of the block in the molten state), and allows the liquid phase containing a sufficient amount of impurities to be easily separated from the block. Therefore, this aluminum raw material manufacturing method easily and sufficiently removes the impurities from the block, allowing the solid phase with a reduced impurity concentration (the block from which the impurities have been removed) to be easily obtained as a high-purity aluminum raw material.

[0013] (2) In the above (1), the heat insulating member may be disposed over the entire area of ​​the pressing member that contacts the mass in a plan view. By disposing the heat insulating member over the entire area of ​​the pressing member that contacts the mass in a plan view, a decrease in the temperature of the mass can be effectively suppressed.

[0014] (3) In the above (1) or (2), the heat insulating member may be a porous body having a plurality of voids or a cotton-like state. The recovered aluminum raw material may have a portion of the heat insulating member attached thereto. When the aluminum raw material is melted, the heat insulating member being a porous body or a cotton-like body makes it easier for a portion of the heat insulating member to float in the molten metal, thereby facilitating the removal of the portion of the heat insulating member in the molten metal.

[0015] (4) In any of the above (1) to (3), the pressing step may involve pressing with a pressing member whose temperature has been elevated. By pressing with a pressing member whose temperature has been elevated, a decrease in the temperature of the aggregate can be further suppressed.

[0016] (5) A method for producing an aluminum raw material according to another aspect of the present disclosure includes the steps of: heating an aluminum lump containing impurities to a semi-molten state; pressing the heated lump with a pressing member; and recovering a solid phase, which is separated from a liquid phase containing at least a portion of the impurities by pressing the lump, as an aluminum raw material; and the step of heating the pressing member.

[0017] In the method for producing an aluminum raw material, the press device for pressing the lumps presses the lumps by increasing the temperature of a pressing member that presses the lumps, thereby suppressing temperature changes in the lumps being pressed and suppressing a reduction in the effect of discharging the impurities from the lumps. Therefore, the method for producing an aluminum raw material can easily and sufficiently remove the impurities from the lumps, and can easily obtain a solid phase with a reduced impurity concentration as a high-purity aluminum raw material.

[0018] (6) In any of (1) to (5), the method may further include a step of placing the lumps on a filtering member. By placing the lumps on the filtering member and pressing them, the liquid phase can be easily separated from the remainder (solid phase) of the lumps.

[0019] (7) In the above (6), a release agent may be applied to the filtering member. By applying a release agent to the filtering member, the ease of recovering the solid phase can be improved.

[0020] (8) In any of (1) to (7) above, the temperature of the A7075 series aluminum alloy mass may be increased to a temperature of 600° C. or more and 620° C. or less in the heating step. By increasing the temperature of the A7075 series aluminum alloy mass to a temperature of 600° C. or more and 620° C. or less, it is possible to improve the ease with which the impurities flow into the liquid phase.

[0021] (9) In any of (1) to (8), the lumps may be formed from scrap of pure aluminum or an aluminum alloy. That is, the method for producing an aluminum raw material is suitable for effectively removing impurities contained in scrap of pure aluminum or an aluminum alloy to produce an aluminum raw material.

[0022] (10) A method for producing an aluminum material according to one aspect of the present disclosure includes the steps of melting an aluminum raw material produced by any one of the production methods (1) to (9) above, and casting the melted aluminum raw material.

[0023] In this method for producing an aluminum material, the aluminum raw material produced by any one of the methods (1) to (9) above is melted and cast, and therefore an aluminum material with high purity can be obtained.

[0024] (11) In the above (10), a step of plastically working the cast aluminum raw material may be further included. By plastically working the cast aluminum raw material, a wrought aluminum material having a desired shape and a low concentration of unnecessary components can be obtained.

[0025] (12) A pressing device according to one aspect of the present disclosure is a device for pressing an aluminum lump, and includes a heating member for heating the lump placed inside, a pressing member for pressing the heated lump, and an insulating member placed between the lump and the pressing member.

[0026] In the compressing device, a heat insulating member is disposed between the lumps and the pressing member that presses the heated lumps, thereby suppressing a decrease in temperature of the lumps due to contact with the pressing member and suppressing a reduction in the effectiveness of the impurities being discharged from the lumps. As a result, the compressing device can easily and sufficiently remove the impurities from the lumps, and a solid phase with a reduced concentration of the impurities can be easily obtained as a high-purity aluminum raw material.

[0027] (12) A pressing device according to one aspect of the present disclosure is a device for pressing aluminum lumps containing impurities, and includes a heating member for heating the lumps and a pressing member for pressing the heated lumps, and is configured so that the heating member heats the pressing member together with the lumps.

[0028] In the compressing device, the pressing members that press the heated lumps are heated together with the lumps, so that temperature changes in the lumps being pressed can be suppressed, and a reduction in the effectiveness of the impurities being discharged from the lumps can be suppressed. Therefore, the compressing device can easily and sufficiently remove the impurities from the lumps, and a solid phase with a reduced concentration of the impurities can be easily obtained as a high-purity aluminum raw material.

[0029] (13) In the above (11) or (12), the compressing device may further include a heating unit for heating the pressing member. By including the heating unit for heating the pressing member, the temperature difference between the pressing member and the lumps can be easily reduced, and a decrease in the temperature of the lumps can be further suppressed.

[0030] (14) The compressing device may further include a filter member on which the lumps are placed. By placing the lumps on the filter member and pressing them, the liquid phase can be easily separated from the remainder (solid phase) of the lumps.

[0031] [Details of the embodiment for carrying out the present disclosure] An example of an embodiment of the present disclosure will be described in detail below.

[0032] [First Embodiment] A method for producing an aluminum raw material according to one embodiment of the present disclosure includes the steps of heating an aluminum mass containing impurities to a semi-molten state, pressing the heated mass with a pressing member, and recovering a solid phase obtained by separating a liquid phase containing at least a portion of the impurities by pressing the mass as an aluminum raw material, wherein a heat insulating member is disposed between the pressing member and the mass in the pressing step. The method for producing an aluminum raw material may be performed using a pressing apparatus 1 as shown in FIG.

[0033] <Compression Device> The compression device 1 includes a temperature-raising member 12 that raises the temperature of lumps B placed inside, a pressing member 21 that presses the heated lumps B, and a heat insulating member 30 that is placed between the lumps B and the pressing member 21. Specifically, the compression device 1 includes a temperature-raising unit 10 and a pressing unit 20, with the temperature-raising member 12 being placed in the temperature-raising unit 10 and the pressing member 21 being placed in the pressing unit 20.

[0034] The compressing device 1 further includes a base 50 including a filter member 40 on which the lumps B are placed. The lumps B are disposed in the pressing unit 20. In this embodiment, the pressing unit 20 and the base 50 are disposed in the heating unit 10.

[0035] [Lump] The lump B is not particularly limited as long as it is made of a material containing unnecessary elements (impurities) when recycled, but is preferably made of an aluminum-based material. The aluminum-based material may be pure aluminum, a 1000-series alloy, a 2000-series alloy, a 3000-series alloy, a 4000-series alloy, a 5000-series alloy, a 6000-series alloy, a 7000-series alloy, or an 8000-series alloy specified by JIS, or may have a composition suitable for casting or die-cast materials. The lump B may be made of scrap pure aluminum or aluminum alloy. In other words, it may be made of recycled pure aluminum or aluminum alloy waste (such as waste that does not meet product requirements and is discarded unused, or waste that has been used as a product and then discarded). The impurities are not particularly limited as long as they are elements that are undesirable for the desired pure aluminum or aluminum alloy, and examples thereof include eutectic elements such as Cu, Fe, Si, Mn, Co, Ni, Zn, and Mg.

[0036] The shape of the lumps B is not particularly limited, and may be one having a regular surface shape such as a sphere or a rectangular parallelepiped, or one having an irregular surface shape. Furthermore, the lumps B may be formed to have an internal space (void), such as a box or a cylinder. The lumps B may be formed in a columnar shape, such as a cylindrical, rectangular, or polygonal columnar shape. By forming the lumps B into a columnar shape and pressing the pressing unit 20 in the axial direction of the lumps B, a uniform pressing force can be applied to the lumps B, improving the ease of efficiently separating the liquid phase.

[0037] [Temperature Raising Unit] The temperature raising unit 10 raises the temperature of the agglomerates B, the pressing unit 20, the filtering member 40, and the base 50 contained therein. The temperature raising unit 10 includes a refractory member 11 placed on the floor or the ground, a cylindrical temperature raising member 12 placed on the refractory member 11, and a heat-resistant board 13 placed on the temperature raising member 12. The refractory member 11 is not particularly limited and may be, for example, a known firebrick. The temperature raising member 12 is not particularly limited and may be, for example, a known heater. The heat-resistant board 13 is not particularly limited and may be, for example, an Al ２ O ３ , SiO ２ The heat-raising unit 10 has an internal space defined by the refractory member 11, the heat-raising member 12, and the heat-resistant board 13. A base 50 on which the filtration member 40 is placed is disposed in this internal space, and the aggregate B and the pressing unit 20 are disposed on the filtration member 40.

[0038] [Pressing Unit] The pressing unit 20 includes a pressing member 21 having a pressing surface 21a that presses the lumps B, a rod 22 connected to the pressing member 21, and a cylindrical sleeve 23 that surrounds the pressing member 21 and the lumps B in a plan view. The rod 22 is connected to the surface (upper surface) of the pressing member 21 opposite the pressing surface 21a. The rod 22 may be formed integrally with the pressing member 21, or may be formed separately from and fixed to the pressing member 21. A portion of the rod 22 passes through a through-hole formed in the heat-resistant board 13 and extends outside the heating unit 10. The rod 22 moves up and down by operation of a drive device (not shown) to which the portion is connected. The pressing member 21 presses the lumps B as the rod 22 moves down.

[0039] The sleeve 23 may be configured to be separable in a direction perpendicular to the axial direction. Specifically, the sleeve 23 may be configured in half, for example, by combining a pair of approximately semicircular members to form an approximately cylindrical shape. By configuring the sleeve 23 to be separable, the remaining portion (solid phase) of the agglomerates B from which the liquid phase has been separated can be easily extracted. The pressing member 21 is arranged in the sleeve 23 so as to be able to move up and down freely.

[0040] It is preferable that a release agent be applied to the inner surface of the sleeve 23. By applying a release agent to the inner surface of the sleeve 23, the pressing member 21 can be easily raised and lowered, and when recovering the solid phase from which the liquid phase has been separated, contact between the solid phase and the inner surface of the sleeve 23 can be prevented, preventing a part (component) of the sleeve 23 from adhering to the solid phase, thereby preventing a decrease in the purity of the solid phase. The release agent is not particularly limited, and examples thereof include boron nitride and alumina.

[0041] [Heat Insulating Member] The heat insulating member 30 is disposed within the sleeve 23 between the lumps B and the pressing surface 21 a, and prevents the heat of the heated lumps B from being transferred to the pressing member 21. In other words, the heat insulating member 30 prevents the pressing member 21 from removing the heat of the heated lumps B. By disposing the heat insulating member 30 between the lumps B and the pressing member 21, it is possible to prevent a decrease in the temperature of the lumps B due to contact with the pressing surface 21 a, and to prevent a decrease in the effect of discharging the impurities from the lumps B.

[0042] The heat insulating member 30 may be placed on the upper surface of the mass B (the surface that contacts the pressing member 21), but is preferably placed on the pressing surface 21a of the pressing member 21. That is, the heat insulating member 30 is preferably fixed to the pressing surface 21a by known means such as adhesive. By fixing the heat insulating member 30 to the pressing surface 21a, the solid phase that has separated from the liquid phase can be easily recovered.

[0043] The material of the insulating member 30 is not particularly limited as long as it has heat resistance of 650°C or higher or 700°C or higher. Examples include oxides such as alumina, silica, lime, magnesia, zirconia, chromia, and hematite, and ceramic fibers. The insulating member 30 may be formed in a sheet or plate shape. The insulating member 30 may also be formed by stacking multiple sheets or plates. The insulating member 30 may also be heat-resistant bricks or a combination of members formed in different materials and shapes. The release agent is not particularly limited and may be the same as the release agent applied to the inner surface of the sleeve 23. The insulating member 30 may also be coated with a known insulating paint.

[0044] The thermal conductivity of the heat insulating member 30 is preferably 0.10 W / m·K or more and 1.0 W / m·K or less at 600° C. By setting the thermal conductivity within the above range, it is possible to effectively prevent the temperature of the mass B from decreasing while also preventing an increase in the cost of the heat insulating member 30.

[0045] The insulating member 30 is preferably a porous or cotton-like body having a plurality of voids. When pressing the mass B, a portion of the insulating member 30 may adhere to the solid phase from which the liquid phase has been separated. When the solid phase recovered as aluminum raw material is melted, the insulating member 30 having a plurality of voids is more likely to float in the molten metal, and can therefore be easily removed from the molten metal. The insulating member 30 preferably has a low bulk density to improve the reliability of floating in the molten metal.

[0046] The heat insulating member 30 is preferably arranged over the entire area of ​​the pressing surface 21a that contacts the mass B in a plan view. That is, when viewed in the pressing direction, the heat insulating member 21 is arranged to cover the entire mass B so that the mass B and the pressing surface 21a do not come into contact with each other. By arranging the heat insulating member 21 so that the mass B and the pressing surface 21a do not come into contact with each other, a decrease in the temperature of the mass B can be effectively suppressed. The heat insulating member 21 may also be arranged over the entire pressing surface 21a. That is, the heat insulating member 30 may be arranged so that the entire pressing surface 21a is covered.

[0047] The lower limit of the ratio of the area where the heat insulating member 30 is arranged to the entire area of ​​the pressing surface 21a is preferably 50%, more preferably 60%, and even more preferably 80%. The upper limit of this ratio is not particularly limited and may be 120% or 100%. By setting the ratio within this range, the ease of the effect of suppressing heat dissipation from the mass B can be improved.

[0048] A first metal flat plate may be disposed between the pressing member 21 and the heat insulating member 30. Also, a second pure aluminum flat plate coated with a release agent may be disposed between the heat insulating member 30 and the mass B, or both the first flat plate and the second flat plate may be disposed. By disposing the first flat plate, the second flat plate, or the first flat plate and the second flat plate, it is possible to improve the ease of uniformly pressing the mass B.

[0049] The base 50 is formed as a cylindrical tank (container) with a bottom, and the filtration member 40 is placed in the opening. By placing the filtration member 40 in the opening of the cylindrical base 50 with a bottom, the liquid phase dripping from the filtration member 40 can be easily stored in the base 50.

[0050] The lumps B and the sleeve 23 of the pressing unit 20 are placed on the filtering member 40. The liquid phase separated from the solid phase of the lumps B is dripped onto the filtering member 40. Specifically, the filtering member 40 has one or more through-holes 41 formed therethrough from the surface (upper surface) on which the lumps B are placed to the opposite surface (lower surface). Alternatively, the filtering member 40 may be formed in a lattice or a rack shape. The shape of the through-hole 41 is not particularly limited and may be a round hole, a rectangular hole, a polygonal hole, an elongated hole, or the like. By having the through-holes 41 in the filtering member 40 or by forming the filtering member 40 in a lattice shape or the like, the liquid phase separated from the solid phase of the lumps B can be easily dripped and separated.

[0051] The material of the filter member 40 is not particularly limited as long as it can withstand the heat and pressure when the lumps B are compressed, and may be, for example, iron, stainless steel, or the like.

[0052] It is preferable that a release agent be applied to the filter member 40. By applying a release agent to the filter member 40, it is possible to prevent the pressed agglomerates B from adhering to the filter member 40, and the solid phase from which the liquid phase has been separated can be easily recovered. In addition, it is possible to prevent a part (component) of the filter member 40 from adhering to the recovered solid phase, thereby preventing a decrease in the purity of the solid phase. The release agent is not particularly limited, and may be the same as the release agent applied to the inner surface of the sleeve 23.

[0053] A suspending device 60 may be placed on the bottom surface of the bottomed cylindrical base 50. The suspending device 60 may have an engaged portion 61 that can be engaged with an engaging member (not shown), such as a hook, a leg portion 62 that supports the engaged portion 61, and a rod-shaped connecting portion 63 that connects the engaged portion 61 to the leg portion 62. The connecting portion 63 may extend upward (away from the bottom surface) from the leg portion 62 so that the engaged portion 61 is positioned above the surface of the stored liquid phase. The shape of the engaged portion 61 is not particularly limited as long as it can be engaged with an engaging member such as a hook, and may be formed, for example, in a ring shape, an inverted U shape, an inverted V shape, a T shape, or the like. By placing the suspending device 60 on the bottom surface of the bottomed cylindrical base 50, the solidified liquid phase can be easily collected. Specifically, after the liquid phase solidifies, the engaging member is inserted into base 50 to engage with engaged portion 61, and the engaging member is then pulled up, allowing the solidified liquid phase together with suspending device 60 to be easily removed from base 50. The material of suspending device 60 is not particularly limited as long as it is heat-resistant, and may be, for example, aluminum, stainless steel, iron, or the like. The suspending device does not need to have legs 62 or connecting portion 63, as long as the engaged portion can stand on its own on the bottom surface. The position of a suspending device that cannot stand on its own is not particularly limited as long as it engages with the engaging member and is partially below the surface of the liquid phase, and it may lean against the side of base 50 or be suspended from filter member 40, for example.

[0054] <Heating Step> In the heating step, the aluminum chunks B containing impurities are heated to a semi-molten state. The temperature to which the chunks B are heated to reach a semi-molten state may be, for example, a temperature at which the solid fraction of the chunks B (the weight ratio of the solid phase to the chunks B) is 20% or more and 70% or less. The lower limit of the solid fraction may be 25% or 30%. The upper limit of the solid fraction may be 65% or 60%. By setting the solid fraction at or above the lower limit, a decrease in the recovery rate of the solid phase can be suppressed. By setting the solid fraction at or below the upper limit, a sufficient liquid phase can be generated and the impurities can be sufficiently discharged into the liquid phase, effectively reducing the impurity concentration in the solid phase.

[0055] In the temperature-raising step, if the mass is made of an A7075-series aluminum alloy, the temperature may be raised to 600° C. or higher and 620° C. or lower. In the case of an A7075-series aluminum alloy mass containing impurities such as Cu and Si, raising the temperature to the above temperature range can improve the reliability of achieving the solid fraction of 30% or higher and 70% or lower.

[0056] The lower and upper limits of the solid fraction may be set appropriately depending on the purpose. For example, when it is desired to reduce the concentration of the impurities in the solid phase (aluminum raw material), the solid fraction may be set to 40% or less, 35% or less, or 32% or less. By setting the solid fraction within the above range, the impurity concentration in the solid phase can be sufficiently reduced. Furthermore, when it is desired to increase the recovery rate of the solid phase, the solid fraction may be set to 50% or more, 55% or more, or 58% or more. By setting the solid fraction within the above range, the recovery rate of the solid phase can be sufficiently improved. In this way, the solid fraction (temperature to be increased) may be adjusted depending on the concentration and type of impurities in the aggregate B, the tolerance for the impurity concentration for the intended use of the recovered solid phase, and the like.

[0057] The relationship between the temperature to be increased and the solid fraction may be calculated, for example, by referring to an equilibrium phase diagram, or by using commercially available thermodynamic calculation software (for example, FactSage manufactured by Thermfact Ltd. / CRCT>T-Technologies).

[0058] In the temperature raising step, it is advisable to also raise the temperature of the pressing member 21. By raising the temperature of the pressing member 21, it is possible to effectively suppress temperature changes in the lumps B being pressed. Depending on the material, the rate at which the temperature of the pressing member 21 rises may be slower than the rate at which the temperature of the lumps B rises. In order to bring the temperature of the pressing member 21 closer to the temperature of the lumps B, the compressing device 1 may be equipped with a heater (not shown) that directly heats the pressing member 21.

[0059] The lumps B may be placed on the filtering element 40 at room temperature and heated by the heating unit 10 until they reach a semi-molten state. Alternatively, they may be heated from room temperature to a predetermined temperature by a heating device (not shown) prepared separately from the compressing device 1, and then placed on the filtering element 40 and heated by the heating unit 10. That is, the heating step may be performed after the step of placing the lumps B on the filtering element 40, or the step of heating the lumps B to a predetermined temperature may be performed after the placing step, followed by the heating step. The predetermined temperature may be a temperature at which the lumps B reach a semi-molten state. In the placing step, another member (an intermediate member) may be placed between the filtering element 40 and the lumps B. By placing the intermediate member between the filtering element 40 and the lumps B, adhesion of a portion (component) of the filtering element 40 to the lumps B can be suppressed. The intermediate member may be formed of the same material as the insulating member 30.

[0060] <Pressing Step> In the pressing step, the heated lumps B are pressed by the pressing member 21. Specifically, the heated lumps B are pressed by the pressing member 21 of the pressing unit 20 in the compression device 1, and the lumps B are separated into a liquid phase containing at least a portion of the impurities and a solid phase in which the concentration of the impurities is reduced. In this pressing step, a heat insulating member 30 (first heat insulating member) is disposed between the lumps B and the pressing member 21 that presses the lumps B in the compression device 1. The heat insulating member 30 only needs to be disposed when the lumps B are pressed. It may be disposed immediately before the pressing member 21 and the lumps B come into contact with each other, but it is preferable that the heat insulating member 30 be disposed before the pressing step. The heat insulating member 30 may be heated before or after being disposed. By preheating the heat insulating member 30 before pressing, the temperature drop of the lumps B during pressing can be further suppressed.

[0061] In this method for producing aluminum raw material, an insulating member 30 is placed between the pressing member 21 that presses the lump B and the lump B, thereby suppressing a drop in temperature due to contact of the lump B with the pressing member 21 and suppressing a reduction in the effect of discharging the above-mentioned impurities from the pressed lump B.

[0062] The temperature change of the mass B due to contact with the insulating member 30 is preferably less than ±20°C, more preferably less than ±15°C, and even more preferably less than ±10°C. By keeping the temperature change within the above range, it is possible to improve the reliability of suppressing the reduction in the impurity discharge effect. The temperature of the mass B may be measured by placing a known thermometer such as a thermocouple inside the mass B.

[0063] The upper limit of the pressing force applied to the lumps B in the pressing step is preferably 2.0 MPa. The lower limit of the pressing force is not particularly limited and may be, for example, 0.1 MPa or 0.3 MPa. By setting the pressing force within the above range, it is possible to improve the reliability of separating the liquid phase from the lumps B while suppressing damage to the compression device 1.

[0064] In this method for producing an aluminum raw material, the lumps B are placed on the filtering member 40 and pressed to separate the liquid phase, and the separated liquid phase passes through the filtering member 40 and is stored in the base 50. Therefore, it is not necessary to solidify the liquid phase and then cut off the solidified portion as in the conventional technology, and the liquid phase can be easily separated. Furthermore, because the lumps B are placed and pressed in the sleeve 23, the separated liquid phase is guided in a direction passing through the filtering member 40, which improves the reliability of separation of the liquid phase from the solid phase and easily improves the purity of the solid phase.

[0065] In the recovery step, the liquid phase containing at least a portion of the impurities is separated by pressing the agglomerate B, and the solid phase is recovered as an aluminum raw material. The solid phase may be recovered by dividing the half-split sleeve 23.

[0066] In the recovering step, the liquid phase may also be recovered. The liquid phase may be recovered by solidifying the liquid phase and then lifting it up by engaging the engaging member with the suspending tool 60 arranged on the bottom surface of the bottomed cylindrical base 50. The liquid phase may be recovered after the heating step and the pressing step are performed on the plurality of lumps.

[0067] The lower limit of the removal rate of the impurities in the solid phase is preferably 40%, more preferably 45%. The upper limit of the removal rate is not particularly limited and may be, for example, 90%, 75%, or 60%. By setting the removal rate within the above range, the production efficiency of high-purity aluminum raw material can be improved. The removal rate is a value calculated by the following formula 1. Note that the "removal rate of the impurities in the solid phase" means the ratio of the impurities contained in the solid phase to the impurities contained in the aggregate B. (B Ｅ -S Ｅ ) / B Ｅ ... (1) Here, B Ｅ is the content [mass%] of impurity elements in the initial agglomerate before the impurity removal treatment, and S Ｅ is the content [mass %] of impurity elements in the recovered solid phase.

[0068] The solidified liquid phase may be subjected to the aluminum raw material manufacturing method as an aluminum lump containing impurities. That is, the solidified liquid phase may be subjected to the heating step, the pressing step, and the recovery step, and a solid phase with reduced impurities may be recovered from the liquid phase as the aluminum raw material. Before the heating step, a sample may be taken from the liquid phase and its components analyzed. By analyzing the components of the liquid phase, the heating temperature in the heating step, the pressing force in the pressing step, and the like can be easily determined.

[0069] [Method for producing aluminum material] The method for producing an aluminum material includes a step of melting the aluminum raw material (solid phase) produced by the method for producing an aluminum raw material, and a step of casting the melted aluminum raw material. Since the aluminum raw material has a reduced impurity concentration, a high-purity aluminum material can be obtained by melting and casting. In the melting step, pure aluminum bullion and one or more alloy elements may be melted together with the aluminum raw material.

[0070] The method for producing an aluminum material may further include a step of plastically working the cast aluminum raw material, which allows a wrought aluminum material having a desired shape and a low concentration of unnecessary components to be obtained by plastically working the cast aluminum raw material.

[0071] [Second embodiment] Another embodiment of the method for producing an aluminum raw material will be described below. Descriptions of the same steps as those in the above-mentioned method for producing an aluminum raw material and the same configurations (members) as those in the above-mentioned compression device will be omitted.

[0072] The method for producing the aluminum raw material includes the steps of heating an aluminum lump containing impurities so that it reaches a semi-molten state, pressing the heated lump with a compression device, and recovering a solid phase, which is separated from a liquid phase containing at least a portion of the impurities by pressing the lump, as the aluminum raw material; in the heating step, the temperature of a pressing member in the compression device that presses the lump is raised.

[0073] <Compression Device> The compression device used in the aluminum raw material manufacturing method includes a heating unit that heats the lumps and a pressing unit that presses the heated lumps, the pressing unit including a pressing member that presses the lumps, and the heating unit heats the pressing member together with the lumps. The compression device further includes a filtering member on which the lumps are placed and a base on which the filtering member is placed. The pressing unit, the filtering member, and the base are disposed within the heating unit, and the lumps are disposed within the pressing unit. The heating unit, the filtering member, and the base may be the heating unit 10, the filtering member 40, and the base 50 described above. The compression device does not include a heat insulating member 30.

[0074] The pressing unit includes a pressing member having a pressing surface that presses the mass, a rod connected to the pressing member, and a cylindrical sleeve that surrounds the pressing member and the mass in a plan view. The rod is connected to the surface (upper surface) of the pressing member opposite the pressing surface. A portion of the rod passes through a through-hole formed in a heat-resistant board of the heating unit and extends outside the heating unit. The rod moves up and down by operating a drive device to which the portion is connected. The pressing member presses the mass as the rod moves down.

[0075] <Temperature Raising Step> In the temperature raising step, the temperature of the lumps is raised to a semi-molten state, and the temperature of the pressing member is also raised. The temperature of the pressing member may be raised so that the pressing surface has substantially the same temperature as the lumps. By raising the temperature of the pressing surface to substantially the same temperature as the lumps, a temperature drop of the lumps due to contact with the pressing member can be suppressed. The pressing member may be heated by a heating member of a heating unit. The pressing member may also be heated by a heating device prepared separately from the compressing device.

[0076] The temperature difference between the heated mass and the pressing member is preferably within 100° C., more preferably within 50° C., and even more preferably within 30° C. By keeping the temperature difference within the above range, the liquid phase can be efficiently exuded and separated from the mass.

[0077] The compressing device may include a first heater that heats the pressing member. By including the first heater in the compressing device, it is possible to improve the ease of setting the pressing member to the temperature range. The first heater may be disposed, for example, on the surface opposite the pressing surface of the pressing member. The compressing device may further include a second heater that heats the rod. By including the second heater in the compressing device that heats the rod, a decrease in temperature of the pressing member is suppressed, thereby further suppressing a decrease in temperature of the agglomerates.

[0078] The temperature change of the mass due to contact with the pressing member is preferably less than ±20° C., more preferably less than ±15° C., and even more preferably less than ±10° C. By keeping the temperature change within the above range, it is possible to improve the reliability of suppressing a decrease in the impurity discharge effect.

[0079] [Other Embodiments] The above-described embodiments do not limit the configuration of the present invention. Therefore, the above-described embodiments may include omissions, substitutions, or additions of components based on the description in this specification and common general technical knowledge, and all of these should be construed as falling within the scope of the present invention.

[0080] The heating unit is not limited to the above-described configuration as long as it is capable of heating the lump, and may be configured, for example, to have a heating device such as a heater disposed on the outer surface of the sleeve of the pressing unit to heat the inside of the sleeve.

[0081] In order to improve the effect of suppressing heat dissipation from the mass, a heat insulating paint may be applied to the pressing surface of the pressing member.

[0082] The present disclosure will be further described below with reference to examples, but the present disclosure is not limited to these examples.

[0083] As a test example, a block of A7075 aluminum alloy containing impurities such as Cu and Si was prepared and compressed using a compression device 1 shown in FIG. 1 . The block was placed on a filter element 40 coated with a release agent (boron nitride) and having slit-shaped through-holes. The filter element 40 was placed on a cylindrical base 50 with a bottom. The heat insulating element 30 consisted of two layers of sheet-like heat insulating material BSSR 1200 blanket 130 (manufactured by Isolite Industries Co., Ltd.; thermal conductivity at 600°C: 0.18 [W / m·K]) stacked on the entire pressing surface 21a. Furthermore, to ensure uniform compression of the block, a pure aluminum plate coated with a release agent on its upper surface was placed between the block and the heat insulating element 30. The block was heated to 620°C (solid fraction 30% based on thermodynamic calculations) and compressed. After completion of the pressing, the heating by the heating unit was stopped to solidify the liquid phase stored in the base 50. The remaining part (solid phase) of the mass from which the liquid phase had been separated and the solidified liquid phase were collected. The results of the temperature change of the mass measured by placing a thermocouple inside the mass are shown in Figure 2.

[0084] As a comparative example, pressing was carried out under the same conditions as in the above test example, except that the insulating member 30 was not used. The temperature change of the lumps in this comparative example is shown in Figure 3. The lumps of the test example and comparative example, and the solid and liquid phases recovered from each, were analyzed for Cu and Si concentrations by ICP atomic emission spectrometry. The results are shown in Table 1.

[0085]

[0086] As shown in Figure 2, in the test example in which the heat insulating member 30 was provided, no drop in the temperature of the mass B was observed at the timing of the start of compression, and it was possible to compress it at the desired temperature (approximately 620°C). As shown in Figure 3, in the comparative example in which the heat insulating member was not provided, the temperature of the mass dropped to below 600°C when the pressing surface of the pressing member came into contact with the mass, and it was not possible to compress it at the desired temperature.

[0087] When the concentrations of impurity elements (Cu and Si) are compared between the solid phase of the test example in which the temperature of the lumps did not decrease during pressing in Table 1 and the solid phase of the comparative example in which the temperature of the lumps decreased during pressing, it can be seen that the solid phase of the test example has reduced impurity elements compared to the solid phase of the comparative example, resulting in a high-purity aluminum raw material. This shows that even without using a heat insulating member, if the pressing member is heated in advance to prevent a decrease in the temperature of the lumps during pressing, a high-purity aluminum raw material can be obtained, just as in the case of using heat insulating member 30.

[0088] The method for producing an aluminum raw material according to the present disclosure can obtain an aluminum raw material with reduced impurities from an aluminum block containing impurities, and is therefore particularly suitable for use in recycling aluminum and aluminum alloys.

[0089] REFERENCE SIGNS LIST 1 Compression device 10 Heat-raising unit 11 Fire-resistant member 12 Heat-raising member 13 Heat-resistant board 20 Pressing unit 21 Pressing member 21a Pressing surface 22 Rod 23 Sleeve 30 Heat-insulating member 40 Filtering member 41 Through-hole 50 Base 60 Suspension member 61 Engagement portion 62 Leg portion 63 Connection portion B Mass

Claims

1. A method for producing aluminum raw material, comprising: a step of heating an aluminum lump containing impurities so that it becomes semi-molten; a step of pressing the heated lump with a pressing member; and a step of recovering a solid phase, which is separated from a liquid phase containing at least a portion of the impurities by pressing the lump, as aluminum raw material, wherein a heat insulating member is placed between the pressing member and the lump in the pressing step.

2. The method for producing aluminum raw material according to claim 1, wherein the heat insulating member is disposed over the entire area of ​​the pressing member that contacts the mass in plan view.

3. The method for producing an aluminum raw material according to claim 1, wherein the heat insulating member is a porous body having a plurality of voids or a flocculent body.

4. The method for producing an aluminum raw material according to claim 1, wherein in the pressing step, the mass is pressed with the pressing member whose temperature has been increased.

5. A method for producing an aluminum raw material, comprising: a step of heating an aluminum lump containing impurities so that the lump reaches a semi-molten state; a step of pressing the heated lump with a pressing member; and a step of recovering a solid phase, which is separated from a liquid phase containing at least a portion of the impurities by pressing the lump, as an aluminum raw material, wherein the temperature of the pressing member is raised in the heating step.

6. The method for producing an aluminum raw material according to claim 1 or claim 5, further comprising the step of placing the lumps on a filtering member.

7. The method for producing an aluminum raw material according to claim 6, wherein the filter member is coated with a release agent.

8. A method for producing an aluminum raw material according to claim 1 or 5, wherein the temperature of the block made of an A7075 series aluminum alloy is raised to a temperature of 600°C or higher and 620°C or lower in the heating step.

9. The method for producing an aluminum raw material according to claim 1 or claim 5, wherein the lumps are formed from scraps of pure aluminum or aluminum alloy.

10. A method for producing an aluminum material, comprising the steps of: melting the aluminum raw material produced by the method of claim 1 or 5; and casting the melted aluminum raw material.

11. The method for producing an aluminum material according to claim 10, further comprising a step of plastically working the cast aluminum raw material.

12. A device for pressing aluminum blocks, comprising: a heating element arranged inside the device to heat the blocks; a pressing element arranged to press the heated blocks; and a heat insulating element arranged between the blocks and the pressing element.

13. An apparatus for compressing aluminum lumps containing impurities, comprising: a heating member arranged inside to heat the lumps; and a pressing member that presses the heated lumps, wherein the heating member is configured to heat the pressing member together with the lumps.

14. The compressing device according to claim 12 or 13, further comprising a heating unit for heating the pressing member.

15. A compressing device according to claim 12 or 13, further comprising a filter member on which the lumps are placed.

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