JP2010265546A - Method for refining metal - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for refining a metal by which a metallic refined material having a composition of low content of impurity and no inclining constitution can continuously be obtained from a metal containing eutectic impurity. <P>SOLUTION: The method includes the following (a)-(b) processes. (a) Primary crystal is generated from the above molten metal in a vessel for generating a first semi-solidified slurry (hereafter, a slurry-generating vessel) to obtain the semi-solidified slurry (hereafter, the slurry), and the primary crystal integrating material (metallic refined material) is formed and recovered by supplying the above slurry to a vessel for first compression (hereafter, a compressive vessel) and also, a liquid phase in the first compressive vessel is supplied to a second slurry-generating vessel and thereafter, a series of operations from the above same slurry supply, is repeated. (b) From the liquid phase supplied to the second slurry-generating vessel, the slurry is generated and supplied to a second compressive vessel to form and recover the primary crystal integration material. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention belongs to a technical field related to a metal refining method, and particularly belongs to a technical field related to a method for refining metal scrap containing eutectic impurities such as Al scrap, and in particular, It belongs to the technical field of Al scrap refining methods.

  In recent years, demand for scrap reuse has increased due to soaring raw materials. These scraps contain a lot of impurity elements, and the use of the refined metal from which impurities have been removed widens the reuse. For example, some Al scrap cannot be reused from product to product, such as clad scrap, and refined Al obtained by refining such Al scrap and removing impurity elements can be reused.

  As a metal refining technique for obtaining such a refined metal, there are a technique described in JP-A-63-42336, a technique described in Japanese Patent No. 3490808, and the like.

  The technology described in Japanese Patent Application Laid-Open No. 63-42336 states that “the molten aluminum in the mold is kept at a predetermined liquid level while being arranged so that it can be lowered to the bottom of the mold, and purified aluminum is placed on the cooled cradle. In the solidification growth method, the plate-like body is moved up and down in the molten metal to press the plate-like body against the upper interface of the solidified and grown aluminum, destroying the crystalline aluminum on the surface, and the molten aluminum present between the aluminum crystals. This is a “continuous aluminum refining method, characterized in that solidified and grown aluminum is continuously obtained as an ingot by extrusion into molten metal”.

  The technology described in Japanese Patent No. 3490808 is described as follows: “A step of cooling a molten metal to be purified to generate primary crystal particles to obtain a molten metal containing primary crystal particles having a solid phase ratio of less than 0.3; A molten metal with a solid phase ratio of less than 0.3 is supplied to the mold, and while cooling in the mold, a molded body with a solid phase ratio of 0.3 to 0.7 with a predetermined cross-sectional shape in which primary crystal particles and concentrated molten metal are mixed. A metal refining method including a step of continuously manufacturing, a step of applying pressure to the obtained molded body to separate and recover the primary crystal particle lump and the concentrated molten metal, and a unit for realizing the same Metal purification equipment ".

JP 63-42336 A Japanese Patent No. 3490808

  The technique described in JP-A-63-42336 has the following problems. In continuous refining, when pressed at a high pressure at which high eutectic impurity elements are expected to be removed, the refined metal may collapse due to the pressure from above, and a purified metal with high purity cannot be obtained. In addition, the impurity composition of the melt separated by continuous consolidation becomes higher each time the growth proceeds, and crystals grown from different liquid phase compositions do not have the same composition. As a result, purified bodies having different compositions in the initial pressing portion and the final pressing portion are produced. That is, it becomes a composition (gradient composition) in which the impurity concentration in the refinement zone increases toward the final part.

  The technique described in Japanese Patent No. 3490808 has the following problems. This technique is a method of continuous purification to improve productivity, but the separation efficiency is low because solid-liquid separation is performed by applying pressure to a semi-solidified product having no fluidity. The weight of the purified product in the examples is almost 20% of the raw material, and productivity is not high.

  The present invention has been made in view of such circumstances, and the object thereof is from a metal containing a eutectic impurity to a composition having a low content of this impurity and not a gradient composition (hereinafter also referred to as a uniform composition). It is an object of the present invention to provide a method for purifying a metal capable of continuously obtaining a purified metal product.

  As a result of intensive studies to achieve the above object, the present inventors have completed the present invention. According to the present invention, the above object can be achieved.

  The present invention completed as described above and capable of achieving the above object relates to a metal purification method, and the metal purification method according to any one of claims 1 to 6 (metal purification method according to the first to sixth inventions). It has the following configuration.

That is, the method for purifying a metal according to claim 1 is a method for purifying a metal having the following steps (a) to (b) [first invention].
(a) A molten metal containing eutectic impurities is accommodated in the first semi-solidified slurry generating vessel, and this molten metal is cooled to a temperature below the liquidus and above the solidus to generate primary crystals and semi-solid. A coagulated slurry is generated, and this semi-coagulated slurry is supplied to the first squeeze container to form a primary crystal accumulation layer and a liquid phase layer. A crystal aggregate is formed, and the primary crystal aggregate is taken out from the first pressing container and recovered as a metal refined body, and the liquid phase in the first pressing container is used as a second semi-solidified slurry generating container. After that, a series of operations from the supply of the semi-solid slurry similar to the above to the first squeeze container to the supply of the liquid phase in the first squeeze container to the second semi-solid slurry generation container are repeated. Process.
(b) The liquid phase supplied to the second semi-solidified slurry generating container is cooled to a temperature below the liquidus and above the solidus to generate primary crystals, thereby generating a semi-solid slurry. Is supplied to the second squeeze container to form the primary crystal accumulation layer and the liquid phase layer, and then the primary crystal accumulation layer is squeezed and pressed to form the primary crystal aggregate. The crystal agglomerate is taken out from the second pressing container and recovered as a metal refined body, and the liquid phase in the second pressing container is discharged out of the second pressing container. A step of repeatedly performing a series of operations from the generation of the slurry to the discharge of the liquid phase in the second pressing container.

The metal purification method according to claim 2 is a metal purification method characterized by having the following steps (a) to (c) [second invention].
(a) A molten metal containing eutectic impurities is accommodated in the first semi-solidified slurry generating vessel, and this molten metal is cooled to a temperature below the liquidus and above the solidus to generate primary crystals and semi-solid. A coagulated slurry is generated, and this semi-coagulated slurry is supplied to the first squeeze container to form a primary crystal accumulation layer and a liquid phase layer. A crystal aggregate is formed, and the primary crystal aggregate is taken out from the first pressing container and recovered as a metal refined body, and the liquid phase in the first pressing container is used as a second semi-solidified slurry generating container. After that, a series of operations from the supply of the semi-solid slurry similar to the above to the first squeeze container to the supply of the liquid phase in the first squeeze container to the second semi-solid slurry generation container are repeated. Process.
(b) The liquid phase supplied to the second semi-solidified slurry generating container is cooled to a temperature below the liquidus and above the solidus to generate primary crystals, thereby generating a semi-solid slurry. Is supplied to the second squeeze container to form the primary crystal accumulation layer and the liquid phase layer, and then the primary crystal accumulation layer is squeezed and pressed to form the primary crystal aggregate. The crystal agglomerate is taken out from the second pressing container and recovered as a metal refined body, and the liquid phase in the second pressing container is supplied to the third semi-solidified slurry generating container. A step of repeatedly performing a series of operations from the generation of the semi-solidified slurry to the supply of the liquid phase in the second pressing container to the third semi-solidified slurry generating container.
(c) The liquid phase supplied to the third semi-solidified slurry generating container is cooled to a temperature below the liquidus and above the solidus to generate primary crystals, thereby generating a semi-solid slurry. Is supplied to the third pressing container to form the primary crystal accumulation layer and the liquid phase layer, and then the primary crystal accumulation layer is squeezed and pressed to form the primary crystal aggregate. The crystal aggregate is taken out from the third pressing container and recovered as a metal refined body, and the liquid phase in the third pressing container is discharged out of the third pressing container. A step of repeatedly performing a series of operations from the generation of the slurry to the discharge of the liquid phase in the third pressing container.

  The metal purification method according to claim 3 is the metal purification method according to claim 1 or 2, wherein the semisolid slurry has a solid phase ratio of 0.2 to 0.4.

  The metal refining method according to claim 4, wherein a pressing pressure when pressing the primary crystal accumulation layer is 3 to 10 MPa, and a pressing time is 3 to 5 minutes. [4th invention].

  The metal purification method according to claim 5 is the metal purification method according to any one of claims 1 to 4, wherein the accumulation layer is cooled when the primary crystal accumulation layer is pressed [fifth invention].

  The method for purifying a metal according to claim 6, after forming the primary crystal aggregate, heating and holding at a temperature equal to or lower than the liquidus or higher than the solidus before pressing out from the pressing container, and pressing. It is a purification method of the metal in any one of Claims 1-5 [5th invention].

  According to the method for purifying a metal according to the present invention, a metal refined body having a composition (uniform composition) having a low content of impurities and a non-gradient composition can be continuously obtained from a metal containing eutectic impurities.

It is a schematic diagram which shows the example of the apparatus for implementing this invention.

  The removal rate of impurities and the recovery rate of purified metal have a contradictory relationship because the liquid phase between crystals must be discharged above the separated solid phase, considering the length of the discharge path. That is, a high purified metal recovery rate cannot be obtained with a high impurity removal rate. Continuous squeezing can realize both a high impurity removal rate and a high purified metal recovery rate by laminating purified metals having a high impurity removal rate. However, with only one squeeze container (hereinafter also referred to as a metal refining unit), a refined body having a gradient composition is produced for the following reason.

  In this method, the semi-solid slurry is supplied to the liquid phase separated by pressing. At this time, since the supply amount is the purified solid phase fraction separated in the pressing step, in order to keep the solid phase ratio of the metal purification section at 0.2 to 0.4, the primary crystal in the residual liquid phase It is necessary to go out. Since the primary crystal concentration is crystallized from the impurity-concentrated liquid phase, it becomes higher than the primary crystal concentration in the initial semi-solidified slurry. Furthermore, the liquid phase concentration also increases due to the formation of primary crystals. Therefore, in the refinement | purification site | part by the next pressing, an impurity concentration will become a little higher than the refinement | purification site | part by the last press by pressing of a high concentration primary crystal, and presence of a high concentration undrained liquid phase. Therefore, a metal refined body having a composition (gradient composition) in which the impurity concentration increases from the lower part (initial compressed part) to the upper part (final compressed part) of the refined body when pressing is repeated in one metal refined part (compression container). Can be done.

  On the other hand, since the metal purification method according to the present invention is a metal purification method having the above-described configuration, a liquid phase (impurity-concentrated liquid phase) is obtained for each squeezing in the squeezing container (metal purification unit). The semi-solid slurry is supplied to the squeezing container after the slag is discharged. For this reason, a metal refined body that does not have a composition (gradient composition) in which the impurity concentration increases from the lower part to the upper part each time (for each squeezing) Can be made.

  That is, the metal refining method [first invention] according to the present invention is characterized by having the steps (a) to (b). In the step (a), the first semi-solid slurry is produced. A molten metal containing eutectic impurities is contained in a container for use, and the molten metal is cooled to a temperature below the liquidus and above the solidus to generate primary crystals, and a semi-solid slurry (liquid phase and primary crystals). And a semi-solid slurry is supplied to the first squeeze container (metal refining section) to form a primary crystal accumulation layer (a little liquid phase coexists) and a liquid phase layer. Then, the primary crystal accumulation layer is squeezed and compacted to form primary crystal aggregates (no liquid phase or almost no liquid phase), and this primary crystal aggregate Is taken out from the first pressing container and recovered as a refined metal, and the liquid phase (impurity-concentrated liquid phase) in the first pressing container is second semi-solidified slurry. It supplies to a container for a composition (metal refinement | purification part), and after this, the 2nd of the liquid phase (impurity concentration liquid phase) in the container for 1st pressing from supply to the container for 1st pressing of the semi-solidified slurry similar to the above Since a series of operations leading to the supply to the semi-solidified slurry generation container is repeated, a composition that is not a gradient composition (uniform composition) every time the primary crystal aggregate (hereinafter also referred to as a metal refined body) is recovered. A purified metal product can be obtained. Moreover, since these refined metal products have the same composition, the same composition is obtained each time the refined metal product is recovered.

  In step (b), the liquid phase (impurity-concentrated liquid phase) supplied to the second semi-solidified slurry generation vessel is cooled to a temperature below the liquidus and above the solidus to generate primary crystals. A semi-solid slurry is produced, and this semi-solid slurry is supplied to the second pressing container (metal refining unit) to form a primary crystal accumulation layer and a liquid phase layer, and then this primary crystal accumulation layer is compressed. Then, the primary crystal aggregate is formed by pressing and solidifying, and the primary crystal aggregate is taken out from the second pressing container and recovered as a metal refined body, and the liquid phase (impurity concentration) in the second pressing container is recovered. The liquid phase is discharged out of the second pressing container, and then a series of operations from the generation of a semi-solid slurry similar to the above to the discharging of the second pressing container liquid phase (impurity-concentrated liquid phase) is performed. Since it is performed repeatedly, every time the metal refined body is recovered, a metal refined body having a uniform composition (a composition that is not a gradient composition) is obtained. Obtainable. Moreover, since these refined metal products have the same composition, the same composition is obtained each time the refined metal product is recovered.

  Thus, in the step (a), a purified metal product having the same composition with a uniform composition (non-gradient composition) can be obtained one after another every time the refined metal product is recovered. In the step (b), the refined metal product is obtained. Each time the body is recovered, a purified metal body having a uniform composition (non-gradient composition) and a similar composition can be obtained one after another.

  This is because the liquid phase (impurity-concentrated liquid phase) of the primary crystal generation target in the process (b) has a higher impurity concentration than the molten metal of the primary crystal generation target in the process (a). In general, the purified metal obtained in the step (b) has a higher impurity concentration than the purified metal obtained in the step (a), but the impurity content is low and sufficient. is there.

  As can be seen from the above, according to the method for purifying a metal according to the present invention, from a metal containing an eutectic impurity, a metal refined body having a composition (uniform composition) having a low content of this impurity and a non-gradient composition is successively obtained. Can be obtained (continuously). At this time, the refined metal obtained in the step (a) has the same composition, and the refined metal obtained in the step (b) has the same composition. Therefore, in the steps (a) to (b), it is possible to obtain continuously (one after another) purified metal products having a low impurity content and a uniform composition and the same composition (first invention).

  Since the metal purification method [first invention] according to the present invention has the steps (a) to (b) as described above, it can be said to be a two-stage metal purification method. Instead of this, when the single-stage metal purification method is used, the recovery rate of the metal purified product is lowered. That is, it does not have the step (b), and in the step (a), the liquid phase (impurity-concentrated liquid phase) in the first squeezing vessel is converted into the second semi-solidified slurry generating vessel (metal refining section). If the liquid phase in the first squeeze container is discharged outside the first squeeze container instead of supplying to the squeeze container, this liquid phase should obtain a purified metal having a sufficiently low impurity content. Therefore, the recovery rate of the metal refined product (ratio of the amount of the metal refined product to the amount of the original metal to be refined) is lowered, and the productivity is lowered.

  In addition, the metal refining method [second invention] according to the present invention is characterized by having the steps (a) to (c). In the step (a), the first semi-solid slurry is produced. A molten metal containing eutectic impurities is contained in a container for use, and the molten metal is cooled to a temperature below the liquidus and above the solidus to generate primary crystals, and a semi-solid slurry (liquid phase and primary crystals). And a semi-solid slurry is supplied to the first squeeze container (metal refining section) to form a primary crystal accumulation layer (a little liquid phase coexists) and a liquid phase layer. Then, the primary crystal accumulation layer is squeezed and compacted to form primary crystal aggregates (no liquid phase or almost no liquid phase), and this primary crystal aggregate Is taken out from the first pressing container and recovered as a refined metal, and the liquid phase (impurity-concentrated liquid phase) in the first pressing container is second semi-solidified slurry. It supplies to a container for a composition (metal refinement | purification part), and after this, the 2nd of the liquid phase (impurity concentration liquid phase) in the container for 1st pressing from supply to the container for 1st pressing of the semi-solidified slurry similar to the above Since a series of operations leading to the supply to the semi-solidified slurry generation container is repeated, a composition that is not a gradient composition (uniform composition) every time the primary crystal aggregate (hereinafter also referred to as a metal refined body) is recovered. A purified metal product can be obtained. Moreover, since these refined metal products have the same composition, the same composition is obtained each time the refined metal product is recovered.

  In step (b), the liquid phase (impurity-concentrated liquid phase) supplied to the second semi-solidified slurry generation vessel is cooled to a temperature below the liquidus and above the solidus to generate primary crystals. A semi-solid slurry is produced, and this semi-solid slurry is supplied to the second pressing container (metal refining unit) to form a primary crystal accumulation layer and a liquid phase layer, and then this primary crystal accumulation layer is compressed. Then, the primary crystal aggregate is formed by pressing and solidifying, and the primary crystal aggregate is taken out from the second pressing container and recovered as a metal refined body, and the liquid phase (impurity concentration) in the second pressing container is recovered. Liquid phase) is supplied to the third semi-solidified slurry production container (metal refining section), and then the production of the same semi-solid slurry as above to the second squeeze container liquid phase (impurity-concentrated liquid phase) Since the series of operations leading to the supply to the third semi-solidified slurry generation container is repeated, metal refining Each time the body (primary crystal aggregate) is collected, a purified metal body having a uniform composition (a composition that is not a gradient composition) can be obtained. Moreover, since these refined metal products have the same composition, the same composition is obtained each time the refined metal product is recovered.

  In step (c), the liquid phase (impurity-concentrated liquid phase) supplied to the third semi-solidified slurry generation vessel is cooled to a temperature below the liquidus and above the solidus to generate primary crystals. A semi-solid slurry is generated, and this semi-solid slurry is supplied to the third pressing container (metal refining section) to form a primary crystal accumulation layer and a liquid phase layer, and then this primary crystal accumulation layer is compressed. Then, the primary crystal aggregate is formed by pressing and solidifying, and the primary crystal aggregate is taken out from the third pressing container and recovered as a metal purified body, and the liquid phase (impurity concentration) in the third pressing container is recovered. The liquid phase is discharged out of the third pressing container, and then a series of operations from the generation of the semi-solid slurry similar to the above to the discharging of the third pressing container liquid phase (impurity-concentrated liquid phase) is performed. Since it is performed repeatedly, every time the metal refined body is recovered, a metal refined body having a uniform composition (a composition that is not a gradient composition) is obtained. Obtainable. Moreover, since these refined metal products have the same composition, the same composition is obtained each time the refined metal product is recovered.

  Thus, in the step (a), a purified metal product having the same composition with a uniform composition (non-gradient composition) can be obtained one after another every time the refined metal product is recovered. In the step (b), the refined metal product is obtained. Each time the body is recovered, a metal refined body having a uniform composition (non-gradient composition) and a similar composition can be obtained one after another. In the step (c), a uniform composition (gradient) is successively applied each time the refined metal body is recovered. A purified metal having the same composition can be obtained with a composition other than the composition.

  The liquid phase (impurity-enriched liquid phase) of the primary crystal generation target in the step (b) has a higher impurity concentration than the molten metal of the primary crystal generation target in the step (a), and (c) Due to the higher impurity concentration in the liquid phase (impurity-concentrated liquid phase) that is the target of primary crystal generation in the process of step (a), it is usually compared with the refined metal obtained in the process (a) ( The refined metal obtained in the step (b) has a high impurity concentration, and the refined metal obtained in the step (c) has a higher impurity concentration, but the impurity content is low and sufficient.

  As can be seen from the above, according to the method for purifying a metal according to the present invention, from a metal containing an eutectic impurity, a metal refined body having a composition (uniform composition) having a low content of this impurity and a non-gradient composition is successively obtained. Can be obtained (continuously). At this time, the refined metal obtained in the step (a) has the same composition, the refined metal obtained in the step (b) has the same composition, and the refined metal obtained in the step (c). The purified product has the same composition. Therefore, in the steps (a) to (c), it is possible to obtain continuously (one after another) a purified metal having a low impurity content, a uniform composition, and a similar composition [second invention].

  Since the metal purification method [second invention] according to the present invention has the steps (a) to (b) as described above, it can be said to be a two-stage metal purification method. The productivity of the second invention is higher than that of the first invention.

  If the 4-stage metal purification method is used instead of the metal purification method according to the second invention (3-stage metal purification method), the impurity concentration of the metal purification product obtained in the 4th stage is high and insufficient. It will be something. That is, instead of discharging the liquid phase (impurity-concentrated liquid phase) in the third pressing container to the outside of the third pressing container in the step (c), the liquid phase in the third pressing container is changed to the first. (4) The liquid phase supplied to the fourth semi-solidified slurry generating container is cooled to a temperature below the liquidus and above the solidus to generate primary crystals. To produce a semi-solid slurry, and supply the semi-solid slurry to the fourth squeeze container to form a primary crystal accumulation layer and a liquid phase layer. The primary crystal aggregate is solidified to be taken out of the fourth pressing container and recovered as a metal refined body, and the liquid phase (impurity-concentrated liquid phase) in the third pressing container is recovered. ) To the outside of the third pressing container, the primary crystal aggregate recovered from the fourth pressing container, that is, the fourth stage The impurity concentration of the metal purification product obtained becomes insufficient in high. For the reasons described above, the metal purification method according to the second invention is a three-stage metal purification method. However, the refined metal obtained in the step (d), that is, the refined metal obtained in the fourth stage, depending on the operating conditions such as pressing conditions (pressure and time) in each step (a) to (d) Therefore, depending on the target value of the impurity concentration, a four-stage metal purification method may be used. In the same sense, a five-stage metal purification method may be used. However, stricter operating conditions, on the other hand, lead to a decrease in productivity, etc. In view of this point, etc., it is recommended that a two- to three-stage metal refining method like the first to second inventions is recommended. Come.

  As described above, the liquid phase (impurity-enriched liquid phase) of the primary crystal generation target in the process (b) has an impurity concentration higher than that of the metal melt of the primary crystal generation target in the process (a). The liquid phase (impurity-concentrated liquid phase) that is the target of primary crystal generation in the step (c) is usually higher in the impurity concentration. In comparison, the refined metal obtained in the step (b) has a high impurity concentration, and the refined metal obtained in the step (c) has a higher impurity concentration. However, depending on the pressing conditions (pressure, etc.) in each step of (a) to (c), the impurity concentration in the purified metal product can be changed, so in each step of (a) to (c) The impurity concentration of the obtained metal refined body can be made to be the same, so that it is possible to collect a large amount of the metal refined body having the same composition.

  An example of an apparatus for carrying out the present invention is shown in FIG. The operation in this apparatus is performed as follows when the semi-solidified slurry is in the metal refining units 1 to 3 (first to third pressing containers).

(1) In the metal refining units 1 to 3, the solid and liquid are separated almost simultaneously. That is, the pressing plate is lowered from the upper part of the metal refining unit (pressing container) to form the primary crystal accumulation layer and the liquid phase layer, and then the pressing plate is further lowered, or the cradle is moved from the lower part. The primary crystal accumulation layer is squeezed and pressed to form a primary crystal accumulation body (metal refined body).
(2) Then, this purified metal is recovered. The liquid phase (concentrated molten metal) in the metal purification unit is first discharged from the metal purification unit 3, then discharged from the metal purification unit 2, and then discharged from the metal purification unit 1. This discharge operation and subsequent operations are performed in the following procedure in detail.

  Final molten metal discharge shutter: Open → Final concentrated liquid phase recovery → Final molten metal discharge shutter: Closed → Molten liquid level adjustment shutter 3: Open → Supply of slurry 3 to metal refining unit 3 → Molten liquid level adjustment shutter 3 : Closed → Concentrated molten metal discharging shutter 2: Opened → Discharged concentrated molten metal of metal refining unit 2 to semi-solidified slurry generating unit 3 → Molten liquid level adjusting shutter 2: Opened → Supply of slurry 2 to metal refining unit 2 -> Molten liquid level adjustment shutter 2: Closed-> Concentrated molten metal discharge shutter 1: Open-> Concentrated molten metal from the metal refining unit 1 is discharged to the semi-solidified slurry generating unit 2-> Molten liquid level adjustment shutter 1: Open-> Metal Slurry 1 supply to refining unit 1 → Molten liquid level adjustment shutter 1: Closed

  (3) After that, repeat (1) and (2) above.

  In the metal refining method according to the present invention, the lower the solid fraction of the semi-solid slurry, the easier it is to supply the semi-solid slurry to the squeeze container. Moreover, although the purity of the metal refinement | purification body obtained becomes high (content of an impurity is low), the quantity of the metal refinement | purification body obtained by one pressing decreases. The higher the solid phase ratio of the semi-solidified slurry, the greater the amount of the purified metal obtained by one pressing, but the lower purity of the obtained purified metal (high impurity content), It becomes difficult to efficiently supply the coagulated slurry to the squeezing container (without waste) and always at a constant solid phase ratio. From this point, it is desirable that the solid phase ratio of the semi-solid slurry is 0.2 or more and 0.4 or less [third invention]. When the solid fraction of the semi-solidified slurry is 0.2 or more and 0.4 or less, the semi-solid slurry can be efficiently supplied to the squeeze container (without waste) and always at a constant solid fraction and is obtained. The purity of the metal purified product is sufficiently high (impurity content is sufficiently low), and the amount of the metal purified product obtained by one pressing is sufficiently large.

  If the pressing pressure when pressing the primary crystal accumulation layer is less than 3 MPa, the liquid phase between the primary crystals cannot be sufficiently squeezed, and even if this pressing pressure exceeds 10 MPa, the liquid between the primary crystals The squeezing effect of the phase is not so different from the case of 3 to 10 MPa. Further, by maintaining the pressure, the liquid phase can be sufficiently discharged even at a relatively low pressure. The holding time is suitably 3 to 5 minutes, and even if the holding time exceeds 5 minutes, a significant improvement in the effect cannot be obtained. From this point, it is desirable that the pressing pressure when pressing the primary crystal accumulation layer is 3 to 10 MPa, and the pressing time is 3 to 5 minutes [fourth invention].

  When the integrated layer is cooled during the pressing of the primary crystal accumulation layer, the primary crystal aggregate obtained by pressing is also cooled, so that the collapse of the aggregate may be more reliably suppressed [fifth invention]. As this cooling means, a cooling pipe such as a copper pipe is preferably provided in the lower part of the squeezing container.

  When the primary crystal accumulation layer is squeezed and compacted to form the primary crystal aggregate, the primary crystal accumulation layer is compacted while being cooled and becomes the primary crystal aggregate. At this time, the impurity-concentrated liquid phase in the primary crystal accumulation body may be solidified without being sufficiently discharged. In this case, the primary crystal aggregate (metal refined body) obtained is in a state where the impurity concentrated liquid phase is solidified (hereinafter, the impurity concentrated liquid phase solidified) is mixed. The purity of the refined metal decreases in proportion to the amount of the solidified product of the impurity-concentrated liquid phase and the impurity concentration.

  Therefore, after the primary crystal accumulation layer is squeezed and formed to form the primary crystal aggregate, it is heated and held at a temperature equal to or lower than the liquidus and above the solidus before being removed from the container for pressing. It is desirable to do so [Sixth Invention]. If it does in this way, the fall of the purity by mixing of the solidified material of the above impurity-concentrated liquid phases can be reduced or prevented. Details will be described below. After forming the primary crystal aggregate, before heating it out of the container for pressing, if heated to a temperature equal to or lower than the liquidus or higher than the solidus, the solidified product of the impurity-concentrated liquid phase is only contained in the primary crystal aggregate. Dissolves (the primary crystal part does not dissolve). Next, when this is squeezed, the dissolved one (impurity-concentrated liquid phase) can be squeezed out from the primary crystal aggregate. Accordingly, it is possible to reduce or prevent a decrease in purity due to the mixture of the solidified product of the impurity concentrated liquid phase as described above. Therefore, a highly purified metal product can be obtained. The retention time at the temperature below the liquidus or above the solidus depends on the rate of temperature rise or cooling from the lower part of the metal purification unit, but the solidified product of the impurity-concentrated liquid phase in the primary crystal aggregate. It suffices if the time is sufficient to dissolve.

  As in the case of the fifth aspect of the invention, there is a case where the accumulation layer is forcibly cooled when the accumulation layer of the primary crystal is pressed. In other cases, the accumulation layer is naturally cooled when the primary crystal accumulation layer is pressed. In the case of the former (forced cooling), the cooling rate is higher than in the case of the latter (natural cooling), so that the impurity-concentrated liquid phase is likely to solidify in the primary crystal accumulation body. Such purity deterioration is likely to occur due to the inclusion of solidified impurities concentrated liquid phase. Therefore, particularly in the former case, it is desirable to apply the means according to the sixth invention.

  In the step (a) of the metal refining method according to the present invention, from the supply of the semi-solid slurry to the first squeeze container to the supply of the liquid phase in the first squeeze container to the second semi-solid slurry generation container When a series of operations are repeated, the semi-solid slurry in the first semi-solid slurry generating container gradually decreases. Eventually, the amount of the semi-solidified slurry supplied to the first pressing container becomes insufficient, and subsequent operations cannot be performed. In such a case, after such or before this, a molten metal containing eutectic impurities is accommodated in the first semi-solidified slurry generation vessel, and the molten metal is liquidized. Cool to a temperature below the phase line and above the solidus to generate primary crystals to form a semi-solid slurry, and then perform the step (a), and then the steps (b) and (c). If the process is performed, the metal purification method according to the present invention can be performed again.

  The semi-solid slurry (specification of the solid phase ratio) according to the third invention may be all (three types) of the semi-solid slurry in the steps (a) to (c), or one or two types. However, it is desirable to target three types. The primary crystal accumulation layer (specification of pressing pressure and time) according to the fourth aspect of the invention may be directed to all (three types) of primary crystal accumulation layers in the steps (a) to (c). Alternatively, two types may be targeted, but it is desirable to target three types. The primary crystal accumulation layer (cooled during pressing) in the fifth invention may be all (three types) of primary crystal accumulation layers in the steps (a) to (c) described above. Species may be targeted, but it is desirable to target three species. The primary crystal aggregates (heated and squeezed) in the sixth invention may target all (three types) of primary crystal aggregates in the steps (a) to (c), or one or two primary crystal aggregates. Species may be targeted, but it is desirable to target three species.

  Examples of the present invention will be described below. It should be noted that the present invention is not limited to this embodiment, and can be implemented with appropriate modifications within a range that can be adapted to the spirit of the present invention. Included in the range.

[Example A]
Al scrap was refined using the apparatus shown in FIG. Details will be described below. As the first to third squeezing containers (metal refining parts 1 to 3), a cradle that is inscribed in the mold and slides up and down at the bottom of a cylindrical graphite mold having an inner diameter of 130 mm and a height of 500 mm. In addition, a pressing plate that is provided on the upper part of the mold and that is inscribed in the mold and that can slide up and down is used. This compaction plate has a disk shape and is provided with 28 hot water holes having a diameter of 5 mm so that the liquid phase squeezed out by pressing is efficiently separated. The vertical stroke is 150mm.

  Using Al-1.60wt% Si-0.14wt% Fe alloy (Al containing Si and Fe, 1.60wt% and 0.14wt%, respectively) as Al scrap to be refined, the following (a) to (c ) Was performed. Note that Si and Fe correspond to eutectic impurities. That is, Si and Fe are eutectic elements that exhibit a eutectic reaction with Al, and are impurities. A eutectic impurity is an impurity element that exhibits a eutectic reaction with a base metal element, such as Si and Fe in Al.

  (a) The above Al scrap is melted to obtain a molten metal, and this molten metal is supplied to the semi-solidified slurry generating chamber 1 (first semi-solidified slurry generating container). The semi-solid slurry 1 was produced by cooling to the above temperature (640 ° C.) to generate primary crystals. This semi-solid slurry 1 is maintained at a temperature of 640 ° C. and has a solid phase ratio of 0.3. The semi-solid slurry 1 is supplied to the metal refining unit 1 (first pressing container), and the compaction plate is lowered in the metal refining unit 1 to form a primary crystal accumulation layer and a liquid phase layer, The primary crystal accumulation layer was squeezed and pressed by the compaction plate and the cradle of the metal refining unit 1 to form primary crystal aggregates. The primary crystal aggregate (Al refined body 1) is recovered from the metal refining unit 1 and the liquid phase (impurity-concentrated liquid phase) in the metal refining unit 1 (first pressing container) is semi-solidified slurry. It supplied to the production | generation chamber 2 (2nd container for semi-solidified slurry production | generation). Thereafter, from the supply of the same semi-solid slurry 1 to the metal refining unit 1 (first pressing container) as described above, the liquid phase (impurity-concentrated liquid phase) in the metal refining unit 1 (first pressing container) is half. A series of operations up to the supply to the solidified slurry generation chamber 2 (second semi-solidified slurry generation container) was repeated. In addition, the compression pressure in the case of the said compression was made into 2 types, 4 MPa and 6.5 MPa. The pressing time was 3 minutes.

  (b) The liquid phase (impurity-concentrated liquid phase) supplied to the semi-solidified slurry generation chamber 2 (second semi-solidified slurry generation container) in the step (a) is below the liquidus line in the slurry generation chamber 2. A semi-solid slurry 2 was produced by cooling to a temperature above the solidus (635 ° C.) to generate primary crystals. The semi-solid slurry 2 is maintained at a temperature of 635 ° C. and has a solid phase ratio of 0.3. This semi-solidified slurry 2 is supplied to the metal refining unit 2 (second squeezing container), and the compaction plate is lowered in the metal refining unit 2 to form an accumulation layer and a liquid phase layer of primary crystals, The primary crystal accumulation layer was squeezed and pressed with a compaction plate and a cradle of the metal refining unit 2 to form primary crystal aggregates. The primary crystal aggregate (Al refined body 2) is recovered from the metal refining unit 2 and the liquid phase (impurity-concentrated liquid phase) in the metal refining unit 2 (second pressing container) is semi-solidified slurry. It supplied to the production | generation chamber 3 (3rd semi-solidified slurry production | generation container). Thereafter, in the step (a), the liquid phase (impurity-concentrated liquid phase) in the metal refining unit 1 (first pressing container) is transferred to the semi-solid slurry generation chamber 2 (second semi-solid slurry generation container). Every time it is supplied, the semi-solid slurry 2 similar to the above is generated, and the semi-solid slurry generation chamber 3 (third semi-solid) in the liquid phase (impurity-concentrated liquid phase) in the metal refining unit 2 (second pressing container). A series of operations up to the supply to the slurry generation container) were repeated. In addition, about the pressing pressure in the case of the said pressing, it is set to 4 MPa in the case of the pressing pressure of 4 MPa in the step (a), and in the case of the pressing pressure of 6.5 MPa in the step (a), it is 6.5 MPa. It was. The pressing time was 3 minutes.

  (c) The liquid phase (impurity-concentrated liquid phase) supplied to the semi-solid slurry generation chamber 3 (third semi-solid slurry generation container) in the step (b) is reduced below the liquidus line in the slurry generation chamber 2. A semi-solid slurry 3 was produced by cooling to a temperature above the solidus (635 ° C.) to generate primary crystals. This semi-solid slurry 3 is maintained at a temperature of 635 ° C. and has a solid phase ratio of 0.3. The semi-solid slurry 3 is supplied to the metal refining unit 3 (third squeezing container), and the compaction plate is lowered in the metal refining unit 3 to form a primary crystal accumulation layer and a liquid phase layer, The primary crystal accumulation layer was squeezed and pressed by the compaction plate and the cradle of the metal refining unit 3 to form primary crystal aggregates. The primary crystal aggregate (Al refined product 3) is taken out from the metal purification unit 3 and recovered, and the liquid phase (impurity-concentrated liquid phase) in the metal purification unit 3 (third squeezing container) is removed from the container. And recovered in the final concentrated molten metal recovery section. Thereafter, in the step (b), the liquid phase (impurity-concentrated liquid phase) in the metal refining unit 2 (second pressing container) is transferred to the semi-solid slurry generation chamber 3 (third semi-solid slurry generation container). Each time it was supplied, a series of operations from the generation of the semi-solid slurry 3 similar to the above to the discharge of the liquid phase (impurity-concentrated liquid phase) in the metal refining unit 3 (third pressing container) was repeated. . In addition, about the pressing pressure in the case of the said pressing, it is set to 4 MPa in the case of the pressing pressure of 4 MPa in the step (a), and in the case of the pressing pressure of 6.5 MPa in the step (a), it is 6.5 MPa. It was. The pressing time was 3 minutes.

  As a result of performing the steps (a) to (c), in the steps (a) to (c), the Al refined body having the same composition with a non-gradient composition (uniform composition) was continuously obtained ( One after another).

  Table 1 shows the composition of each initial molten metal (contents of impurities Si and Fe) and the composition of each purified product (contents of impurities Si and Fe) in the steps (a) to (c). Each initial molten metal is a molten metal before the production of the semisolid slurry in the step (a) (dissolved Al scrap), and a liquid phase (impurities) before the production of the semisolid slurry in the step (b). Concentrated liquid phase), that is, the liquid phase (impurity concentrated liquid phase) before being supplied to the semi-solidified slurry generation chamber 2 in the step (a), and the liquid before the semi-solidified slurry generation in the step (c) This is the phase (impurity-enriched liquid phase), that is, the liquid phase (impurity-enriched liquid phase) before being supplied to the semi-solidified slurry production chamber 3 in the step (b). On the other hand, each refined body is obtained by collecting the primary crystal aggregate (Al refined body 1) recovered in the step (a) and the primary crystal aggregate (Al purified) obtained in the process (b). Purified product 2) refers to the primary crystal aggregate (Al purified product 3) obtained by recovery in the step (c). The final residual liquid is the liquid phase (impurity-concentrated liquid phase) discharged and recovered from the metal refining unit 3 (third pressing container) to the final concentrated molten metal recovery unit in the step (c).

  As can be seen from Table 1, the amount of impurity elements (Si, Fe) in the molten metal (refined Al scrap) before refining treatment is Si: 1.60 wt% and Fe: 0.14 wt%. In the case of pressing pressure at the time of pressing: 4 MPa, the Al refined body 1 has an impurity element (Si, Fe) amount of Si: 0.69 wt% and Fe: 0.10 wt%, and is more impurity element than the melt before the purification treatment. The content of Si and Fe is low. In the Al refined body 2, the content of the impurity element Si is higher than that in the case of the Al refined body 1, but is lower than the molten metal before the purification treatment. In the Al refined body 3, the content of the impurity element Si is higher than that in the case of the Al refined body 2, but is lower than the molten metal before the purification treatment.

  In the case of pressing pressure at the time of pressing: 6.5 MPa, the Al refined body 1 has a lower content of impurity elements Si and Fe than the molten metal before the purification treatment. The Al refined body 2 has a higher content of impurity elements Si and Fe than that of the Al refined body 1, but has a lower content of impurity elements Si and Fe than the melt before the purification treatment. In the Al refined body 3, the content of the impurity element Si is higher than that in the case of the Al refined body 2, but is lower than the molten metal before the purification treatment.

  The results in Table 1 show that the Al refined body 1 obtained at the beginning of the above step (a) (first time in the repeated operation) and the first (at the first time in the repeated operation) of the above step (b). Al purified product 2 obtained in the above step (c), and the Al purified product 3 obtained at the beginning of the above step (c) (first operation), but the nth product (n = 2, 3, 4, 5, ...) Al purified body 1, Al purified body 2 and Al purified body 3 obtained were almost the same and almost the same in composition.

  Therefore, in the above steps (a) to (c), an Al refined body having the same composition with a composition (homogeneous composition) having a lower content of impurities than the material to be refined (Al scrap) and a non-gradient composition (uniform composition). It was confirmed that it can be obtained continuously (one after another).

  In addition, in the case of pressing pressure at the time of pressing: 4 MPa, the Al refined body 3 has a higher content of Fe as an impurity element than the molten metal before the purification treatment, and the pressing pressure at the time of pressing: 6.5 MPa. The Al refined body 3 has a higher Fe content of the impurity element than the molten metal before the refining treatment. Therefore, it can be said that this example is suitable when it is desired to reduce the Si content of the impurity element. If it is desired to reduce the Fe content of the impurity element, the operating conditions may be changed, thereby reducing the Fe content of the impurity element. For example, by increasing the cooling temperature when generating the semi-solidified slurry, decreasing the solid phase ratio of the semi-solidified slurry, increasing the pressing pressure at the time of pressing, increasing the pressing time, etc. The content of the impurity element Fe can also be reduced.

[Example B]
The same apparatus as in Example A was used as the apparatus, and Al scrap similar to that in Example A was used as the Al scrap to be refined, and the following steps (a1) to (c1) were performed.

  (a1) After the formation of the primary crystal aggregate in the metal purification unit 1 by the same method (process and conditions) as in the step (a) of Example A, the liquidus below the solidus Heat to temperature (640 ° C.) and hold for 1 minute, then squeeze at squeezing pressure: 6.5 MPa, and then collect the primary crystal aggregate (Al purified body 1) from the metal purification section 1 and collect it. At the same time, the impurity concentrated liquid phase in the metal refining unit 1 was supplied to the semi-solidified slurry production chamber 2. In addition, the pressing time in pressing after the heating was 3 minutes. The pressing pressure for pressing the primary crystal accumulation layer was 6.5 MPa, and the pressing time was 3 minutes.

  (b1) After the formation of the primary crystal aggregate in the metal purification unit 2 by the same method (process and conditions) as in the step (b) of Example A, the liquidus below the solidus Heat to temperature (635 ° C.) and hold for 1 minute, and then squeeze at squeezing pressure: 6.5 MPa. After that, this primary crystal aggregate (Al refined product 2) is taken out from the metal purification unit 2 and recovered. At the same time, the impurity concentrated liquid phase in the metal refining unit 2 was supplied to the semi-solidified slurry production chamber 3. In addition, the pressing time in pressing after the heating was 3 minutes. The pressing pressure for pressing the primary crystal accumulation layer was 6.5 MPa, and the pressing time was 3 minutes.

  (c1) After forming the primary crystal aggregate in the metal refining unit 3 by the same method (process and conditions) as in the case of the step (c) of Example A, Heat to temperature (635 ° C.) and hold for 1 minute, then squeeze at squeezing pressure: 6.5 MPa, and then collect this primary crystal aggregate (Al purified product 3) from the metal purification unit 3 and collect it. At the same time, the impurity concentrated liquid phase in the metal refining unit 3 was discharged out of the container and recovered in the final concentrated molten metal recovery unit. In addition, the pressing time in pressing after the heating was 3 minutes. The pressing pressure for pressing the primary crystal accumulation layer was 6.5 MPa, and the pressing time was 3 minutes.

  Table 2 shows the compositions (contents of impurities Si and Fe) of the Al purified products 1 to 3 obtained in the steps (a1) to (c1) of Example B above. Al refined bodies 1 to 3 obtained in the steps (a) to (c) of Example A, and those having a pressing pressure of 6.5 MPa, and those of (a1) to (c1) of Example B above The Al purified products 1 to 3 obtained in the process are compared. The Al purified products 1 to 3 obtained in the steps (a1) to (c1) of Example B are the Al purified products 1 to 3 (pressed) obtained in the steps (a) to (c) of Example A. Compared with the pressure (6.5 MPa), the contents of impurity elements Si and Fe are low. That is, the Al purified product 1 in Example B has the same Fe content as the Al purified product 1 in Example A, but the Si content is low, and the Al purified product 2 in Example B is an example. Compared with the Al refined body 2 in A, the contents of Si and Fe are lower, and the Al refined body 3 in Example B has a lower content of Si and Fe than the Al purified body 3 in Example A. ing.

  Since the metal purification method according to the present invention can continuously obtain a metal refined body having a composition (homogeneous composition) having a low content and a non-gradient composition from a metal containing eutectic impurities, Al It can be suitably used as a refining method for refining scraps so that they can be reused.

Claims (6)

A metal purification method comprising the following steps (a) to (b):
(a) A molten metal containing eutectic impurities is accommodated in the first semi-solidified slurry generating vessel, and this molten metal is cooled to a temperature below the liquidus and above the solidus to generate primary crystals and semi-solid. A coagulated slurry is generated, and this semi-coagulated slurry is supplied to the first squeeze container to form a primary crystal accumulation layer and a liquid phase layer. A crystal aggregate is formed, and the primary crystal aggregate is taken out from the first pressing container and recovered as a metal refined body, and the liquid phase in the first pressing container is used as a second semi-solidified slurry generating container. After that, a series of operations from the supply of the semi-solid slurry similar to the above to the first squeeze container to the supply of the liquid phase in the first squeeze container to the second semi-solid slurry generation container are repeated. Process.
(b) The liquid phase supplied to the second semi-solidified slurry generating container is cooled to a temperature below the liquidus and above the solidus to generate primary crystals, thereby generating a semi-solid slurry. Is supplied to the second squeeze container to form the primary crystal accumulation layer and the liquid phase layer, and then the primary crystal accumulation layer is squeezed and pressed to form the primary crystal aggregate. The crystal agglomerate is taken out from the second pressing container and recovered as a metal refined body, and the liquid phase in the second pressing container is discharged out of the second pressing container. A step of repeatedly performing a series of operations from the generation of the slurry to the discharge of the liquid phase in the second pressing container. A metal purification method comprising the following steps (a) to (c):
(a) A molten metal containing eutectic impurities is accommodated in the first semi-solidified slurry generating vessel, and this molten metal is cooled to a temperature below the liquidus and above the solidus to generate primary crystals and semi-solid. A coagulated slurry is generated, and this semi-coagulated slurry is supplied to the first squeeze container to form a primary crystal accumulation layer and a liquid phase layer. A crystal aggregate is formed, and the primary crystal aggregate is taken out from the first pressing container and recovered as a metal refined body, and the liquid phase in the first pressing container is used as a second semi-solidified slurry generating container. After that, a series of operations from the supply of the semi-solid slurry similar to the above to the first squeeze container to the supply of the liquid phase in the first squeeze container to the second semi-solid slurry generation container are repeated. Process.
(b) The liquid phase supplied to the second semi-solidified slurry generating container is cooled to a temperature below the liquidus and above the solidus to generate primary crystals, thereby generating a semi-solid slurry. Is supplied to the second squeeze container to form the primary crystal accumulation layer and the liquid phase layer, and then the primary crystal accumulation layer is squeezed and pressed to form the primary crystal aggregate. The crystal agglomerate is taken out from the second pressing container and recovered as a metal refined body, and the liquid phase in the second pressing container is supplied to the third semi-solidified slurry generating container. A step of repeatedly performing a series of operations from the generation of the semi-solidified slurry to the supply of the liquid phase in the second pressing container to the third semi-solidified slurry generating container.
(c) The liquid phase supplied to the third semi-solidified slurry generating container is cooled to a temperature below the liquidus and above the solidus to generate primary crystals, thereby generating a semi-solid slurry. Is supplied to the third pressing container to form the primary crystal accumulation layer and the liquid phase layer, and then the primary crystal accumulation layer is squeezed and pressed to form the primary crystal aggregate. The crystal aggregate is taken out from the third pressing container and recovered as a metal refined body, and the liquid phase in the third pressing container is discharged out of the third pressing container. A step of repeatedly performing a series of operations from the generation of the slurry to the discharge of the liquid phase in the third pressing container.   The method for purifying a metal according to claim 1 or 2, wherein the semisolid slurry has a solid phase ratio of 0.2 to 0.4.   The metal refining method according to any one of claims 1 to 3, wherein a pressing pressure when pressing the primary crystal accumulation layer is 3 to 10 MPa, and a pressing time is 3 to 5 minutes.   The method for purifying a metal according to any one of claims 1 to 4, wherein the accumulation layer is cooled when the accumulation layer of the primary crystal is pressed. After forming the said primary crystal aggregate, before taking out from the said container for pressing, it heats to the temperature more than a liquidus line and below a solidus line, hold | maintains, and squeezes. Metal purification method.

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