JP5486181B2 - Continuous metal purification method - Google Patents

Description

  The present invention is a continuous metal refining process in which a metal refined body obtained by removing impurity elements from metal scrap containing eutectic impurities such as aluminum (hereinafter referred to as “Al”) scrap at a high rate can be obtained at a high recovery rate. It is about the method.

  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, for example, it is difficult to simply recycle the scraps into the products. 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, Patent Document 1 discloses a method in which purified Al is solidified and grown on a cradle that is arranged so that it can be lowered to the lower part of the mold while maintaining the Al molten metal in the mold at a predetermined liquid level. The plate-like body is operated up and down inside, and the plate-like body is pressed against the upper interface of the solidified and grown Al to destroy the crystalline Al on the surface, and the molten Al existing between the crystalline Al is extruded into the molten metal. A method for continuously refining Al in which the solidified and grown Al is continuously obtained as an ingot is disclosed.

Patent Document 2 discloses a step of cooling a molten metal to be purified to generate primary crystal particles, and obtaining a molten metal having a solid phase ratio of less than 0.3 including the primary crystal particles; The molten metal having a solid phase ratio of less than 0.3 is supplied to the mold, and while cooling in the mold, the solid phase ratio of a predetermined cross-sectional shape in which the primary crystal particles and the concentrated molten metal are mixed is 0.3 to 0.00. And a method for purifying a metal comprising a step of continuously producing a molded body of No. 7 and a step of applying pressure to the obtained molded body to separate and recover the primary crystal particle lump and the concentrated molten metal. A metal refining device with a unit to be realized is disclosed.
JP 63-42336 A Japanese Patent No. 3490808

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

  That is, the method for continuously purifying Al described in Patent Document 1 may cause the refined metal to collapse due to pressure from above when pressed at a high pressure at which impurity elements are expected to be removed at a high rate. As a result, a purified metal with high purity cannot be obtained.

  Moreover, although the metal purification method described in Patent Document 2 is a continuous purification method, the separation efficiency is low because solid-liquid separation is performed by applying pressure to a semi-solidified product having no fluidity. That is, the impurity element removal rate is lowered. Also, with this method, the weight of the purified product can be obtained only up to about 50% of the molten metal (raw material) to be purified.

  There has never been a continuous metal purification method that can overcome the above problems.

  An object of the present invention is to provide a continuous metal purification method capable of obtaining a metal refined body obtained by removing impurity elements at a high rate from metal scrap containing eutectic impurities at a high recovery rate.

In order to achieve this object, the invention according to claim 1 of the present invention provides:
A process for generating a semi-solid slurry containing a primary crystal by cooling a molten metal scrap containing eutectic impurities to a temperature below the liquidus and above the solidus, and a push capable of moving up and down The semi-solid slurry is supplied to a continuous squeeze container provided with a compaction plate and a descendable cradle so as to reach a predetermined liquid level, and the compaction plate is pressed from above the liquid level of the supplied semi-solid slurry. The primary crystal aggregate and the concentrated liquid phase are formed, and a predetermined pressure is applied to the primary crystal aggregate by the compaction plate, and the primary crystal aggregate and the remaining liquid are pressed. Separating the squeezed primary crystal aggregate (referred to as "previous squeezed primary crystal aggregate") with the cradle below the continuous squeeze container, The semi-solid slurry containing the primary crystals in the remaining liquid phase part up to the predetermined liquid level Fill the semi-solid slurry and replenish the compaction plate again from above the liquid level of the remaining liquid phase part to refill the new primary crystal on the previous compressed primary crystal aggregate. And forming a concentrated liquid phase, applying a predetermined pressure to the newly formed primary crystal aggregate by the compaction plate, and newly pressing the primary crystal aggregate and the remaining liquid. This new squeezed primary crystal aggregate and the previous squeezed primary crystal aggregate (these squeezed primary crystal aggregates together, A series of steps of lowering the primary crystal aggregate) together with the cradle to the lower side of the container for continuous pressing, and recovering the metal refined body in which the compressed primary crystal aggregates are laminated. A process for continuously purifying metal, comprising the step of:

  According to a second aspect of the present invention, in the first aspect of the present invention, the semisolid slurry has a solid phase ratio of less than 0.3.

  The invention according to claim 3 is the invention according to claim 1, wherein the predetermined pressure applied to the primary crystal aggregate by the compaction plate is 3 to 10 MPa, and the holding time of the pressure is 3 to 5 minutes.

According to a fourth aspect of the present invention, in the first aspect of the present invention, a pipe having a cooling means is installed below the continuous pressing container.

  According to the method for continuously purifying metal according to the present invention, the repetitive squeezing is performed while the semi-solid slurry containing fresh primary crystals is sequentially replenished from the upper part of the continuous squeezing container and the first squeezed downward of the continuous squeezing container. Since the refined metal body in which the crystal agglomerates are stacked is continuously lowered, a refined metal body in which the impurity elements are removed at a high rate from the metal scrap containing the eutectic impurities can be obtained at a high recovery rate. By using such semi-solid slurry, a metal refining method that repeatedly squeezes continuously, a metal that removes impurity elements from the above metal scrap at a higher rate than a batch-type metal refining method. The recovery rate of the purified product is increased.

  Hereinafter, the present invention will be described in detail while illustrating embodiments.

(Configuration of the continuous metal purification method according to the present invention)
The method for continuously purifying metals according to the present invention includes:
A process for generating a semi-solid slurry containing a primary crystal by cooling a molten metal scrap containing eutectic impurities to a temperature below the liquidus and above the solidus, and a push capable of moving up and down The semi-solid slurry is supplied to a continuous squeeze container provided with a compaction plate and a descendable cradle so as to reach a predetermined liquid level, and the compaction plate is pressed from above the liquid level of the supplied semi-solid slurry. The primary crystal aggregate and the concentrated liquid phase are formed, and a predetermined pressure is applied to the primary crystal aggregate by the compaction plate, and the primary crystal aggregate and the remaining liquid are pressed. Separating the squeezed primary crystal aggregate (referred to as "previous squeezed primary crystal aggregate") with the cradle below the continuous squeeze container, The semi-solid slurry containing the primary crystals in the remaining liquid phase part up to the predetermined liquid level Fill the semi-solid slurry and replenish the compaction plate again from above the liquid level of the remaining liquid phase part to refill the new primary crystal on the previous compressed primary crystal aggregate. And forming a concentrated liquid phase, applying a predetermined pressure to the newly formed primary crystal aggregate by the compaction plate, and newly pressing the primary crystal aggregate and the remaining liquid. This new squeezed primary crystal aggregate and the previous squeezed primary crystal aggregate (these squeezed primary crystal aggregates together, A series of steps of lowering the primary crystal aggregate) together with the cradle to the lower side of the container for continuous pressing, and recovering the metal refined body in which the compressed primary crystal aggregates are laminated. And a step of performing.

  Below, the fundamental principle of the continuous purification method of the metal which concerns on this invention is demonstrated. FIG. 1 is a schematic diagram of a continuous metal purification apparatus used in the purification method, and FIG. 2 is a schematic diagram for explaining the basic principle in time series.

1 and 2, 1 is a semi-solid slurry generating section, 2 is a heater, 3 is a primary crystal, 4 is a semi-solid slurry containing primary crystal 3, and 10 is an inner diameter of 130 mm and a height of 500 mm as a container for continuous pressing. cylindrical graphite mold 11 copper tube as a tube made of a high thermal conductivity provided on the lower portion of the graphite mold 10, 12 is cooling means provided around the copper pipe 11, 13 is semi-solidified slurry A connecting pipe for connecting the generator 1 and the graphite mold 10, 14 is a liquid level adjusting shutter provided in the middle of the connecting pipe 13, and 15 is a descendable outer diameter provided on the lower side of the graphite mold 10. A 130 mm iron cradle 16 is an iron compaction plate having an outer diameter of 120 mm, which can be moved up and down, provided on the upper side of the graphite mold 10.

In FIG. 1, a metal scrap containing eutectic impurities (for example, an alloy composed of Al-1.6 wt% Si-0.1 wt% Fe (Al scrap)) in a semi-solid slurry generating section 1 is melted. The primary crystal 3 is generated by cooling to a temperature below the liquidus and above the solidus. Thereby, the semi-solidified slurry 4 containing the primary crystal 3 is completed. The semi-solid slurry 4 containing the primary crystal 3 is supplied to the graphite mold 10 through the connecting pipe 13 by opening the liquid level adjusting shutter 14.

FIG. 2A shows that the semi-solid slurry 4 containing the primary crystal 3 reaches a predetermined liquid level A through the connecting tube 13 shown in FIG. The state supplied to is shown. Accordingly, the height of the semi-solidified slurry 4 comprising primary crystal 3 becomes h _0.

FIG. 2B shows that the compaction plate 16 is lowered from above the liquid level A of the supplied semi-solid slurry 4 to form an aggregate of the primary crystal 3 and a concentrated liquid phase. the compacted plate 16 pushes the third integrated body by applying a predetermined pressure (first pressing), the remaining liquid phase portion 21a of the stack 20a and the height h _r1 primary crystal 3 squeezed height h ₁ Shows the separated state.

FIG. 2 (c) shows a state where the pressed primary crystal 3 aggregate 20 a having a height h ₁ is lowered together with the cradle 15 below the graphite mold 10. Thereby, the liquid level of the remaining liquid phase portion 21a is lowered below the initial predetermined liquid level A, and a space B that can receive fresh semi-solid slurry 4 is generated.

In FIG. 2D, the liquid level adjustment shutter 14 is opened again, and the fresh semi-solid slurry 4 reaches the predetermined liquid level A from the semi-solid slurry generation unit 1 to the remaining liquid phase portion 21 a through the connecting pipe 13. The state replenished until is shown. Thus, to obtain what again close to 2 semi-solidified slurry containing primary crystals 3 shown in (a) 4 (height h _0).

FIG. 2 (e) shows that the pressing plate 16 is lowered again from above the liquid level (predetermined liquid level A) of the remaining liquid phase portion 21a supplemented with the semi-solid slurry 4 shown in FIG. 2 (d). Then, a new primary crystal 3 aggregate and a concentrated liquid phase are formed on the compressed primary crystal aggregate 20a, and the newly formed primary crystal 3 aggregate is pressed by the compaction plate 16. A state is shown in which a predetermined pressure is applied (second pressing) and the aggregated body 20b of the primary crystal 3 having a height h ₂ and the remaining liquid phase portion 21b having a height h _r2 are separated. As shown in FIG. 1, in the metal continuous refining apparatus of this embodiment, a copper tube 11 having a cooling means 12 provided in the lower part of a graphite mold 10 is installed, so that the pressed primary crystal It is possible to accelerate the solidification of the aggregate 20a and the newly formed aggregate of the primary crystal 3 and to apply a high predetermined pressure during pressing. Therefore, for example, even when the predetermined pressure at the second pressing is higher than the predetermined pressure at the first pressing, the compressed primary crystal aggregate (metal refined body) may collapse. Absent. As a result, more concentrated liquid phase can be removed from the compressed primary crystal 3 accumulated body 20b to the outside, so that the metal purified body from which the impurity elements are removed at a high rate has a higher recovery rate. It will be obtained at.

FIG. 2 (f) stack 20b of the stack 20a and the primary crystal 3 squeezed height h ₂ of the primary crystal 3 squeezed height h ₁ together with cradle 15 below the graphite mold 10 Furthermore, it shows the lowered state. As a result, the liquid level of the remaining liquid phase portion 21b falls below the initial predetermined liquid level A, and a space C in which fresh semi-solid slurry 4 can be received is generated again.

Next, by utilizing the generation of the space C as described above, the liquid level adjustment shutter 14 is opened again and the semi-solid slurry is passed through the connecting pipe 13 in the same manner as described with reference to FIG. A fresh semi-solid slurry 4 is replenished from the generator 1 to the remaining liquid phase portion 21b until a predetermined liquid level A is reached. Thereafter, the integrated body 20c of the pressed primary crystal 3 having a height h ₃ as shown in FIG. 1 is obtained through the same steps as those shown in FIGS. 2 (e) and 2 (f). As a result, a metal refined body laminated in three layers (height h ₁ + h ₂ + h ₃ ) from which the impurity element is finally removed at a high rate can be obtained at a high recovery rate (see FIG. 1).

In the present embodiment, the example in which the metal refined body stacked in the three layers (height h ₁ + h ₂ + h ₃ ) from which the impurity element is finally removed at a high rate has been described has been described. The process is not limited, and the same steps as in FIGS. 2D to 2F may be repeated continuously until a desired recovery rate is obtained.

  By using such semi-solid slurry, a metal refining method that repeatedly squeezes continuously, a metal that removes impurity elements from the above metal scrap at a higher rate than a batch-type metal refining method. The recovery rate of the purified product is increased.

Further, by setting the solid phase ratio of the semi-solid slurry 4 containing the primary crystal 3 to less than 0.3, the graphite mold 10 can be efficiently supplied from the semi-solid slurry generation section 1 through the connecting pipe 13. As a result, more concentrated liquid phase can be excluded from the accumulated body of the primary crystal 3 during pressing, so that a metal refined body from which impurity elements have been removed at a higher rate can be obtained with a higher recovery rate. It becomes like this.

  Moreover, in this embodiment, although the example which makes the predetermined pressure at the time of the 2nd pressing high compared with the predetermined pressure at the time of the 1st pressing was demonstrated, it is not necessarily limited to this, For example, at the time of pressing It is possible to make the applied pressures all the same, change them, or apply various pressures. The predetermined pressure value at the time of pressing is more preferably 3 MPa or more from the viewpoint of sufficiently removing the concentrated liquid phase from the aggregate of the primary crystal 3. However, since the removal rate does not increase so much even if it exceeds 10 MPa, 10 MPa or less is more preferable from the viewpoint of the strength of the primary crystal aggregate to be pressed. Further, by maintaining the predetermined pressure at the time of pressing for a long time, the concentrated liquid phase can be sufficiently removed from the aggregate of the primary crystal 3 even at a low pressure. Taking the effect and productivity into consideration, the holding time of the pressure is more preferably 3 to 5 minutes.

In the present embodiment, the example in which the copper tube 11 provided with the cooling means 12 around the graphite mold 10 is described. However, the present invention is not necessarily limited thereto. What is necessary is just to install suitably considering the removal rate and recovery rate of the impurity element desired for a refined metal body.

  Hereinafter, an example of the continuous metal purification method of the present invention will be described.

  In this example, a confirmation experiment was performed by adopting the configuration shown in FIGS. Therefore, the same constituent elements will be described with the same numbers.

  In this example, an alloy (Al scrap) composed of Al-1.6 wt% Si-0.1 wt% Fe was used as the molten metal scrap containing eutectic impurities. By cooling this molten metal to 640 ° C., primary crystal 3 was generated in the Al scrap molten metal, and semisolid slurry 4 containing primary crystal 3 and having a solid phase ratio of less than 0.3 was completed.

  The pressing plate 16 is provided with 32 hot water holes (not shown) having a diameter of 5 mm so as to efficiently separate the remaining liquid phase portion from the pressed primary crystal 3 aggregate. Yes. Moreover, the raising / lowering stroke of the compaction board 16 is 150 mm.

The pressing conditions were determined as follows.
Applied pressure Holding time 1st time: 4.0 MPa 3 minutes 2nd time: 6.5 MPa 3 minutes 3rd time: 8.0 MPa 3 minutes

Based on the above conditions, by applying a series of steps as shown in the schematic diagram of FIG. 2, the primary crystal 3 squeezed height h ₁ stack 20a, the primary crystal 3 squeezed height h ₂ to obtain a metal refining formed by laminating three layers of an integrated body 20b and the height h ₃ of the squeezed primary crystals 3 of the stack 20c.

As a result of analyzing the composition of the pressed primary crystal 3 aggregates 20a, 20b, and 20c, as shown in Table 1 below, the removal rate of impurity elements (Si, Fe) was extremely high.

Moreover, as a result of examining the recovery rate of the metal refined body laminated in three layers, an extremely high recovery rate of 86% was achieved (see Table 1 above). The definition of the recovery rate follows the following formula (1).
“Recovery rate”
Recovery rate = (Total volume of pressed primary crystal 3 aggregates 20a, 20b, 20c) / (Volume of semi-solid slurry 4 having diameter 130 mm × height h ₀ shown in FIG. 2A) × 100 ( 1)

  In the present embodiment, an example of an alloy (Al scrap) made of a component of Al-1.6% Si-0.1% Fe has been described as a metal scrap molten metal containing eutectic impurities. However, it is possible to use metal scrap containing various eutectic impurities.

  Further, in this example, by taking Al scrap as an example, a primary solid was generated by cooling to 640 ° C. as a temperature below the liquidus and above the solidus, and a semi-solid slurry containing this primary was generated. However, the present invention is not necessarily limited to this, and a metal scrap melt containing various eutectic impurities is cooled to a temperature below the liquidus and above the solidus to generate primary crystals. A semi-solid slurry containing this primary crystal can be generated and used.

  Moreover, in the present embodiment, the example in which the application pressure is increased stepwise for each squeezing has been described, but it is not necessarily limited to this, for example, all the application pressures for each squeezing may be the same, It is possible to change and apply various pressures.

It is a schematic diagram of the continuous purification apparatus of the metal used for the continuous purification method of the metal of one Embodiment of this invention. It is a schematic diagram for demonstrating the basic principle of the purification method in time series.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Semi-solidified slurry production | generation part 2 Heater 3 Primary crystal 4 Semi-solidified slurry 10 Graphite mold 11 Copper pipe 12 Cooling means 13 Connection pipe 14 Liquid level adjustment shutter 15 Receptacle 16 Compaction board 20a, 20b, 20c Accumulated bodies 21a, 21b, 21c of primary crystal 3 Remaining liquid phase part A Predetermined liquid level B, C Space that can receive semi-solid slurry 4

Claims (4)

  A process for generating a semi-solid slurry containing a primary crystal by cooling a molten metal scrap containing eutectic impurities to a temperature below the liquidus and above the solidus, and a push capable of moving up and down The semi-solid slurry is supplied to a continuous squeeze container provided with a compaction plate and a descendable cradle so as to reach a predetermined liquid level, and the compaction plate is pressed from above the liquid level of the supplied semi-solid slurry. The primary crystal aggregate and the concentrated liquid phase are formed, and a predetermined pressure is applied to the primary crystal aggregate by the compaction plate, and the primary crystal aggregate and the remaining liquid are pressed. Separating the squeezed primary crystal aggregate (referred to as "previous squeezed primary crystal aggregate") with the cradle below the continuous squeeze container, The semi-solid slurry containing the primary crystals in the remaining liquid phase part up to the predetermined liquid level Fill the semi-solid slurry and replenish the compaction plate again from above the liquid level of the remaining liquid phase part to refill the new primary crystal on the previous compressed primary crystal aggregate. And forming a concentrated liquid phase, applying a predetermined pressure to the newly formed primary crystal aggregate by the compaction plate, and newly pressing the primary crystal aggregate and the remaining liquid. This new squeezed primary crystal aggregate and the previous squeezed primary crystal aggregate (these squeezed primary crystal aggregates together, A series of steps of lowering the primary crystal aggregate) together with the cradle to the lower side of the container for continuous pressing, and recovering the metal refined body in which the compressed primary crystal aggregates are laminated. A process for continuously purifying metal, comprising the step of:   The method for continuously purifying metal according to claim 1, wherein the semi-solid slurry has a solid phase ratio of less than 0.3.   The method for continuously purifying metal according to claim 1, wherein the predetermined pressure applied to the primary crystal aggregate by the compaction plate is 3 to 10 MPa, and the holding time of the pressure is 3 to 5 minutes. The method for continuously purifying metal according to claim 1, wherein a pipe having a cooling means is installed below the continuous pressing container.

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