JPH07207378A - Device for refining aluminum scrap, method for refining aluminum scrap using the device, and method for using refined aluminum - Google Patents

Abstract

PURPOSE:To provide a device to efficiently refine scrap such as aluminum brazing sheet to high purity. CONSTITUTION:In a fractional crystallizing device of aluminum scrap the liquid phase metal of high concentration is efficiently separated from primarily crystallized particles by satisfying the inequality: 0.95A>=S>=0.75A, where S is the sectional area of a pressing part of a pressing stamp 7, and A is the sectional area inside a molten metal holding container 1. The rest of the molten metal is easily discharged outside from a discharging passage 4 by satisfying the inequality: L>=H-(h), where L is the height of the pressing part of the pressing stamp 7, H is the height inside the molten metal holding container 1, and (h) is the height of the primarily crystallized particles which are pressed, and forming the discharging passage 4 to the upper part of the container 1 to dip the pressing stamp 7 in the molten metal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for efficiently refining aluminum scrap, particularly aluminum brazing sheet scrap, to a high purity, a refining method using the apparatus, and an effective method of using the obtained refined aluminum. .

[0002]

2. Description of the Related Art The development of efficient refining technology for aluminum scrap containing elements such as Fe and Si is the most important issue for effective use of resources and reduction of raw material costs. For example, for tubes that pass the refrigerant of aluminum radiators for automobiles,
Al-1 wt% Mn alloy (JIS-3003 etc.)
A composite material in which a wt% Si alloy (JIS-4043, etc.) is clad is used, and a large amount of slitting scraps and the like of the rolled material are generated during the manufacturing process. Most of such aluminum scrap is reused as low grade metal for casting. If this composite material can be turned into a raw material for wrought material, the raw material cost will be significantly reduced, which will lead to effective use of resources.

As a method for refining aluminum scrap, there is a crystal fractionation method. This method was previously proposed by the inventors of the present invention (Japanese Patent Application No. 5-202361), and its gist is to hold a molten aluminum scrap in a container and to keep the solidus line below the liquidus line of this molten metal. Within the above temperature range, almost all of this melt is 20 ℃ /
It is cooled at a rate of min. or less to produce purified primary crystal particles, and then the pressure stamp is lowered from above to press the primary crystal particles to the lower portion of the container, and the high concentration liquid from the primary crystal particles is generated. This is a method in which the phase metal is squeezed out and separated from the primary crystal grains. Since the primary crystal grains have a dendritic shape and the high-concentration liquid phase metal is trapped between the dendritic branches, a high pressure of 2 to 15 MPa is required to squeeze out the high-concentration liquid phase metal.

[0004]

By the way, in order to separate the primary crystal particle pressing body from the high-concentration liquid-phase metal, the remaining molten metal is solidified on the primary crystal particle pressing body, and the boundary portion is cut with a saw. I was going. However, in this method, the remaining molten metal solidified, and it took a long time for the temperature to drop until the saw could be cut, resulting in low productivity. Therefore, a method of tilting the container to discharge the remaining molten metal has been proposed (Japanese Patent Laid-Open No. 62-15883).
0), tilting was troublesome and there was a problem in safety. Also, using a cylindrical container with both ends open, the lower part of the container is closed by a pressing body for primary crystal particles, the molten metal is replenished from above the container, and the primary crystal particles are pressed while pressing the primary crystal particles with a plate-shaped body. A method has been proposed in which the body is pulled out from the lower part of the container (JP-A-63-42336). This method has a problem that not only the productivity is inferior, but also the molten metal after pressing remains in the container, so that the concentration of the molten metal increases with time and the purification efficiency gradually decreases.

[0005]

DISCLOSURE OF THE INVENTION The present invention has been earnestly studied in such a situation, and an object thereof is an apparatus for efficiently purifying aluminum scrap to high purity and a method for purifying the same. And to provide an effective method of utilizing the obtained purified aluminum. That is, the invention of claim 1 is a molten metal holding container for holding molten aluminum scrap, and the molten metal held in the container is gradually cooled in a temperature range below the liquidus line of the molten metal and above the solidus line. In an aluminum scrap refining device that consists of a pressure stamp that presses the primary crystal particles generated in the molten metal with high pressure to the primary crystal particle generation equipment that generates primary crystal particles, The cross-sectional shape and the cross-sectional shape inside the molten metal holding container have a similar relationship, and the cross-sectional area S of the pressing portion of the pressure stamp and the cross-sectional area A inside the molten metal holding container are 0.95A ≧ S ≧ 0.75A. Satisfying the formula, and the height L of the pressure portion of the pressure stamp and the height H of the inside of the molten metal holding container are L ≧ H−h (where h is the height of the pressed primary crystal grains). It is characterized by satisfying the formula and having a molten metal discharge passage at the upper part of the container. It is intended.

The device of the present invention will be specifically described below with reference to the drawings. FIG. 1 is a side view showing an embodiment of the device of the present invention. In the figure, 1 is a molten metal holding container, which is composed of a cylindrical bottomed body in which a castable refractory 3 is lined in a SUS shell 2. A discharge passage 4 for the remaining molten metal is provided above the container 1. A gutter 5 is attached to the tip of the discharge passage 4.
An electromagnetic induction heater 6 is provided on the outer circumference of the container 1. This electromagnetic induction heater 6 not only raises the temperature of the molten metal,
It can also be applied to the slow cooling of molten metal by lowering the output. Further, it also serves to induce and stir the molten metal by electromagnetic force. A pressure stamp 7 is arranged above the container 1. The pressure stamp 7 is moved up and down by a hydraulic cylinder 8.

FIG. 2 is an explanatory view of the relationship between the molten metal holding container and the pressure stamp which constitute the apparatus of the present invention. The cross-sectional shape of the pressurizing part 9 of the pressurizing stamp 7 and the cross-sectional shape of the inside of the molten metal holding container 1 have a similar relationship, and the cross-sectional area S of the pressurizing part 9 and the cross-sectional area A inside the molten metal holding container 1 are the same. Is 0.95A ≧ S ≧ 0.75A
And the height H of the pressurizing portion 9 and the height H inside the molten metal holding container are L ≧ H−h (where h is the height of the pressed primary crystal grains). I am satisfied with the formula.

In the apparatus of the present invention, the relational expression of 0.95A ≧ S ≧ 0.75A is satisfied between the cross-sectional area A inside the molten metal holding container and the cross-sectional area S of the pressure portion of the pressure stamp. When S exceeds 0.95A, the gap between the inner peripheral surface of the molten metal holding container and the outer peripheral surface of the pressurizing portion of the pressurizing stamp becomes narrow, and it becomes difficult for the high-concentration liquid phase metal to pass through the gap, and the high-concentration liquid phase metal This is because a large amount of is taken into the primary crystal particle pressing body. Also S
If it is less than 0.75 A, the number of primary crystal particles that are not pressed by the pressure stamp increases, and a large amount of high-concentration liquid phase metal remains in the primary crystal particles. If the cross-sectional shape of the pressurizing part of the pressurizing stamp is made similar to the cross-sectional shape of the inside of the molten metal holding container, the gap between the inner peripheral surface of the molten metal holding container and the outer peripheral surface of the pressurizing part of the pressurizing stamp becomes even. Therefore, the high-concentration liquid phase metal squeezed out from the primary crystal particles can be efficiently moved and discharged. Also, the height H in the molten metal holding container and the height L of the pressing portion of the pressing stamp
The relational expression of L ≧ H−h (where h is the height of the pressed primary crystal particles) is satisfied so that the balance is obtained by immersing the pressure part of the pressure stamp. This is to discharge as much molten metal as possible from the container.

In the apparatus of the present invention, the primary crystal grain producing device includes a cooling jacket which is closely attached to the outer periphery of the molten metal holding container and is used as an internal water flow type cooling element immersed in the molten metal. When cooling the melt sufficiently slowly, do not use a cooler, but lower the output of the heater. For the heater, an electromagnetic induction heater is convenient as mentioned above. For stirring the molten metal, a propeller type stirrer used by immersing the molten metal in the molten metal is also applied. The molten metal holding container is preferably one that can withstand a high pressing force, such as a SUS shell with a castable refractory lined therein. As the lining material, graphite is preferable because of its excellent releasability. The cross-sectional shape inside the molten metal holding container is circular,
The shape such as a prism is arbitrary. In the apparatus of the present invention, a molten metal discharge passage is provided above the molten metal holding container, and the remaining molten metal is discharged through this passage. A plurality of discharge passages may be provided, and it is preferable to circulate a hot water receiving trough around the upper part of the container because a large amount of the remaining molten metal can be quickly discharged.

A second aspect of the present invention is a method for refining aluminum scrap using the refining apparatus according to the first aspect, which has a structure in which the aluminum scrap molten metal held in the molten metal holding container is 20 ° C./min. Slowly cool at the following rate to generate a certain amount of primary crystal particles, press the generated primary crystal particles to the bottom of the container with a pressing force of 2 to 15 MPa, and discharge the remaining molten metal at the top of the container The method is characterized in that a step of discharging from the passage, a step of pulling the pressure stamp out of the container, and a step of taking out the primary crystal particle pressing body from the container are sequentially performed.

The invention method of claim 2 will be described in detail with reference to the drawings. 3A to 3D are process explanatory diagrams showing an embodiment of a method for refining aluminum scrap using the invention apparatus according to claim 1. The molten aluminum scrap 10 is heated and held in the molten metal holding container 1 at a temperature above its liquidus line (FIG. 3A). The output of the electromagnetic induction heater 6 around the outer periphery of the container 1 is lowered to gradually cool the molten metal in the container and hold the liquid at a predetermined temperature below the liquidus and above the solidus to generate primary crystal grains 11. During this period, the remaining molten metal 13 is electromagnetically induction stirred by the heater 6 (FIG. 3B). Next, the pressure stamp 7 preheated to a predetermined temperature is lowered, and the primary crystal particles are pressed to the lower portion of the molten metal holding container 1 by the pressure unit 9. A high-concentration liquid-phase metal is squeezed out from the primary crystal particles and mixed into the remaining molten metal 13. The remaining molten metal 13 is discharged from the discharge passage 4 in the upper part of the container 1 through the gutter 5 and stored in a storage tank (not shown) according to the volume of the pressurizing part 9 in the container 1 (FIG. 3C). Next, the pressure stamp 7 is pulled up.
A small amount of the remaining molten metal 13 remains on the primary crystal grain pressing body 12 at the bottom of the container (Fig. 3D). The primary crystal grain pressing body 12 was taken out of the container 1, and the solidified layer of the remaining molten metal 13 attached to the edge was peeled off.

In the method of the second aspect of the present invention, the reason why the cooling rate of the molten metal is limited to 20 ° C./min.
This is because if the temperature exceeds ° C / min., The purity of the primary crystal particles produced will decrease. The reason for limiting the pressure of the primary crystal particles to 2 to 15 MPa is that the high-concentration liquid phase metal trapped in the primary crystal particles cannot be sufficiently squeezed out below 2 MPa, and the high-concentration liquid phase metal above 15 MPa. This is because the squeezing out of is saturated.

The present invention is particularly suitable for removing Si from aluminum scrap containing 0.5 to 10 wt% of Si.
Further, the remaining molten metal discharged by the method of the present invention can be used as a raw material, and this can be repeatedly refined and purified by the method of the present invention. Further, the pressed primary crystal particles purified by the method of the present invention can be widely used as a raw material for wrought materials by blending with other raw materials.

[0014]

In the apparatus of the present invention, the cross-sectional area S of the pressure portion of the pressure stamp and the cross-sectional area A inside the molten metal holding container are 0.95 A ≧ S.
Since the relational expression of ≧ 0.75 A is satisfied, the high-concentration liquid phase metal is efficiently separated from the primary crystal grains. Further, the height L of the pressing portion of the pressing stamp and the height H of the inside of the molten metal holding container are L ≧ H−h.
(However, h is the height of the pressed primary crystal grains) and the molten metal discharge passage is provided in the upper part of the container. For the remaining molten metal, dip the pressure stamp into the molten metal. Is easily discharged to the outside through the passage. or,
Using the above apparatus, the cooling rate of the molten metal is 20 ° C./min. Or less, and by refining by limiting the pressure of the primary crystal particles to 2 to 15 MPa, high-purity primary crystal particles are produced, and the primary crystal particles are also produced. Therefore, the high concentration liquid phase metal can be efficiently squeezed out.

[0015]

EXAMPLES The present invention will be described in detail below with reference to examples. Example 1 On both sides of the core material of Al-1 wt% Mn alloy (JIS-3003 series), A
Various scraps (including casting scraps) generated during the production of an aluminum brazing sheet covered with a 1-7.5 wt% Si alloy (JIS-4343 series) skin material were blended and purified in a large amount. The slow cooling rate of the molten metal and the pressing force of the pressure stamp were variously changed. Several kinds of pressure stamps having different cross-sectional areas of the pressure portion were used. The length L of the pressure portion of the pressure stamp was the same as the height H in the molten metal holding container. The molten metal holding container has an inner diameter
The one with 300 mmφ and the inner height of 500 mm was used. The molten metal temperature at the time of pressurizing the stamp was set to 10 K or lower than the liquidus temperature so that the Si concentration of the primary crystal particle pressing body was 1 wt% or lower. The Si concentration of the obtained primary crystal particle pressing body was analyzed. Moreover, the production amount for one week was measured. The results are shown in Table 1.

[0016]

[Table 1]

As is clear from Table 1, the product of the present invention (N
o.1 to 7) all had a high Si removal rate. The removal rate of Si is S / S when the slow cooling rate is slower or the pressing force is higher.
The larger the A ratio, the better the result. The analysis value of Mn is
It was 0.6 to 0.9 wt%. On the other hand, since the comparative example products (No. 8 to 11) were out of the conditions of the present invention in any of the slow cooling rate, the pressing force, and the S / A ratio, the high-concentration liquid phase metal became the primary crystal particle pressing body. After being incorporated, the Si removal rate decreased. The production increased due to the incorporation of high-concentration liquid metal. In the above manufacturing process, the work was performed smoothly and there was no problem in safety.

Example 2 The residual molten metal discharged in Example 1 was refined by the same method as in Example 1, and the obtained primary crystal particles were refined again. The obtained purified product was analyzed for Si. The results are shown in Table 2.

[0019]

[Table 2]

As is clear from Table 2, even the residual molten metal discharged during the refining could be refined to a purity higher than the result of Example 1 by repeatedly refining twice by the method of the present invention. . The analysis value of Mn after the second purification is 0.7 to 1.
It was 0 wt%.

Example 3 A brazing sheet scrap of Al-3 wt% Si-1 wt% Mn alloy was refined under the same conditions as No. 1 or No. 3 of Example 1. No. 1 composition after purification is Si 0.77 wt%
Mn0.65wt% balance Al, No.3 is Si0.84wt% Mn0.75wt
% The balance was Al. After melting each, add Mn, JIS-
1000 series alloy scrap was blended and reused together as the core material (JIS-3003 series alloy) of the brazing sheet. All of them showed the same good performance and quality as products manufactured only from virgin raw materials.

The case of refining the aluminum radiator task trap containing Si and Mn has been described above.
Even if the present invention is applied to the refining of aluminum scrap containing other elements, the same effect can be obtained.

[0023]

As described above, according to the present invention, aluminum scrap can be efficiently refined, and the obtained refined product can be effectively reused, which is a significant industrial effect.

[Brief description of drawings]

FIG. 1 is a side view showing an embodiment of the device of the present invention.

FIG. 2 is an explanatory view of a relationship between a molten metal holding container and a pressure stamp which constitute the device of the present invention.

FIG. 3 is a process explanatory view showing an embodiment of a method for refining aluminum scrap using the device of the present invention.

[Explanation of symbols]

 1 Molten metal holding container 2 SUS shell 3 Fireproof castable 4 Discharge passage 5 Gutter 6 Electromagnetic induction heater 7 Pressurizing stamp 8 Hydraulic cylinder 9 Pressurizing part of pressurizing stamp 10 Aluminum scrap molten metal 11 Primary crystal grain 12 Primary crystal grain pressing Body 13 remainder molten metal

 ─────────────────────────────────────────────────── --Continued front page (72) Inventor Mitsuhiro Otaki 2-6-1, Marunouchi, Chiyoda-ku, Tokyo Furukawa Electric Co., Ltd.

Claims (5)

[Claims] 1. A molten metal holding container for holding an aluminum scrap molten metal, the molten metal held in the container is gradually cooled within a temperature range below a liquidus line of the molten metal and above a solidus line thereof, and primary crystal particles are obtained. In a device for purifying aluminum scrap, which comprises a primary-crystal particle producing device for producing a primary-crystal particle, and a primary-pressure stamp for pressing primary-crystal particles produced in a molten metal against the bottom of a container with a high pressure, a cross-sectional area S of the pressing portion of the pressing stamp and The cross-sectional area A inside the molten metal holding container satisfies the relational expression of 0.95A ≧ S ≧ 0.75A, and the height L of the pressing portion of the pressure stamp and the height H of the inside of the molten metal holding container.
And L satisfy the relational expression of L ≧ H−h (where h is the height of the pressed primary crystal grains), and a molten metal discharge passage is provided in the upper part of the container for refining aluminum scrap. apparatus. 2. A step of gradually cooling an aluminum scrap molten metal held in a molten metal holding container at a rate of 20 ° C./min. Or less to generate a predetermined amount of primary crystal particles, the generated primary crystal particles by a pressure stamp. Pressing the bottom of the container with a pressing force of 2 to 15 MPa and discharging the remaining molten metal from the molten metal discharge passage at the upper part of the container, pulling the pressure stamp out of the container,
The method for refining aluminum scrap using the apparatus for refining aluminum scrap according to claim 1, wherein steps of taking out the pressed primary crystal particles from the container are sequentially performed. 3. The molten aluminum scrap is at least S.
3. The method of refining aluminum scrap according to claim 2, wherein i is contained in an amount of 0.5 to 10 wt%. 4. The method for refining aluminum scrap according to claim 2 or 3, wherein the residual molten metal discharged by the method for refining aluminum scrap according to claim 2 is used as molten aluminum scrap. 5. A refinement characterized by using the pressed primary crystal particles obtained by the aluminum scrap refining method according to any one of claims 2 to 4 as a raw material for wrought material after blending with other raw materials. How to use aluminum.