Method for removing iron from an aluminium melt

Abstract

The present invention discloses a method for at least partially removing iron from an aluminum melt, comprising the steps of: - generating a thixotropic aluminum melt containing a liquid and a solid phase, and - separating the liquid phase by applying a centrifugal force to the thixotropic aluminum melt.

Description

[0001] The present invention relates to a method for at least partially removing iron from an aluminum melt.

[0002] After steel, aluminum is by far the most important metallic material and is used as the basis for a wide variety of alloys in many areas of modern industry. Iron (Fe) is an unavoidable accompanying element. Even the raw material used in aluminum production, bauxite, contains significant amounts of Fe, which, depending on the quality of the manufacturing process, can also be found in so-called primary aluminum (primary Al) in concentrations of up to 0.2 wt.%.

[0003] For economic and ecological reasons, a significant proportion of aluminum scrap, so-called secondary aluminum, is usually added during aluminum processing. This so-called recycled material is used to incorporate iron into the aluminum alloys in ever-changing product life cycles. This iron content is the core of the invention presented here.

[0004] With few exceptions, iron has a consistently negative effect on the technical properties of aluminum alloys. Depending on the application, certain concentrations of Fe can typically be tolerated without the properties of the aluminum alloys being significantly impaired. This tolerance limit can be as low as about one percent by weight, but can be significantly lower for more demanding applications. At an iron content of more than 1 wt.%, aluminum alloys are unsuitable for most applications. Therefore, the market price of aluminum alloys is directly linked to the Fe content. The higher the iron content, the greater the discount on the price of primary aluminum (typically <0.1-0.2 wt.% Fe).

[0005] The technical problem to be solved by the present invention is to reduce the iron content in Al alloys in order to increase the technical utility and market value of the alloy.

[0006] The problem of Fe contamination in aluminum is well known, and various processes have been proposed and tested to achieve iron depletion in aluminum. Particular mention should be made of processes based on gravitational or centrifugal force. Iron-rich phases in liquid aluminum have a higher density than the residual melt and can therefore, in principle, be separated. Alternatively, processes based on the use of electromagnetic fields have been proposed and investigated, which are intended to achieve the same separation effect. Similarly, other known processes for material and phase separation have been proposed for iron depletion in aluminum, including filtration and sedimentation.

[0007] Document CN102069147A describes the removal of oxides from an aluminum melt by centrifugal filtration. Document CN113621823A shows the purification of an aluminum melt by distillation, where the aluminum melt is first atomized by centrifugation.

[0008] Document CN110819822A demonstrates the removal of Fe and Si from an Al-Fe-Si melt. Mg is first added to the melt as an extractant to extract the Al. Targeted cooling of the AlSiFeMg melt creates a state in which a solid phase enriched in Fe and Si is formed in the melt. The liquid phase, which primarily comprises Al and Mg, is then separated by centrifugal force. In a further process step, the Mg is separated by distillation, producing an Al melt. All of these processes have in common that, while they have a certain potential and some have been successfully tested on a laboratory scale, they have not yet established themselves on the market. The main reasons are technical problems in implementing the processes and their insufficient efficiency.Therefore, it is still state of the art to compensate for excessively high Fe concentrations in Al alloys by diluting them with primary aluminum.

[0009] The object of the present invention is therefore to provide an improved process for at least partially removing iron from an aluminum melt.

[0010] This object is achieved by a method according to claim 1.

[0011] Preferred embodiments of the present invention are the subject of the subclaims.

[0012] The present invention comprises a method for at least partially removing iron from an aluminum melt, comprising the steps: Creating a thixotropic aluminum melt containing a liquid and a solid phase, wherein the thixotropic aluminum melt is produced by controlled cooling of a liquid aluminum melt to a target temperature, and separating the liquid phase by applying a centrifugal force to the thixotropic aluminum melt. The solid phase preferably has a higher Fe content than the liquid phase.

[0013] The target temperature is intended to be in a range of 575°C to 655°C.

[0014] The present invention solves the problem of separating iron by applying centrifugal force to a thixotropic mixture of liquid and solid aluminum contaminated with iron. By creating a thixotropic aluminum melt containing a liquid and a solid phase, a morphology of solid iron phases favorable for the separation process is first created in a residual liquid melt. Subsequently, the liquid components are separated from the solid components by applying centrifugal force. A large portion of the iron remains in the solid portion, so that the liquid portion has a significantly reduced iron concentration compared to the initial state.

[0015] The procedure according to the present invention therefore uses a thixotropic aluminum melt for iron depletion and can therefore also be referred to as thixo- or rheo-separation.

[0016] In one possible embodiment of the present invention, the solid phase is retained, and the liquid phase is separated from the solid phase by applying centrifugal force. According to this aspect, the present invention therefore does not function due to the density differences between the liquid and solid phases. Rather, the solid phase forms a structure from which the liquid phase is extracted by centrifugal force. Centrifugal force is used to overcome the effects of the surface tension of the liquid phase, which causes it to remain within the solid phase.

[0017] In one possible embodiment of the present invention, the solid phase is formed in a 3-dimensionally cross-linked, in particular sponge-like structure, from which the liquid phase is separated by application of centrifugal force, while the solid phase is retained.

[0018] In one possible embodiment of the present invention, the solid phase is formed in the form of particles and / or agglomerates that support one another during separation of the liquid phase, so that the liquid phase is separated from the spaces between the particles and / or agglomerates by the application of centrifugal force, while the solid phase is retained. In particular, these can be three-dimensionally shaped particles and / or agglomerates.

[0019] In one possible embodiment of the present invention, it is provided that the solid phase remains in a container or container region in which the aluminum melt is produced.

[0020] In one possible embodiment of the present invention, it is provided that the liquid phase is separated into a second container or container region.

[0021] As a result, at the end of the separation process, the liquid and solid phases are present in two different containers or container areas and can therefore be easily removed separately.

[0022] In one possible embodiment of the present invention, it is therefore provided that the solid phase is subsequently removed from the container or container region.

[0023] In one possible embodiment of the present invention, it is provided that a retaining element is used which retains the solid phase while the liquid phase is separated.

[0024] In a possible embodiment of the present invention, it is provided that the retaining element is a container in which the thixotropic aluminum melt is produced and which has at least one discharge opening for the liquid phase.

[0025] In one possible embodiment of the present invention, it is provided that the container has a shape that tapers towards a drain opening.

[0026] In one possible embodiment of the present invention, it is provided that the container has a bottom region surrounding the drain opening.

[0027] In particular, the tapered shape and / or the bottom region can form a retaining element which retains the solid phase during separation of the liquid phase.

[0028] In a possible embodiment of the present invention, it is provided that the container is open on the side opposite the drain opening in order to remove the retained solid phase.

[0029] In a possible embodiment of the present invention, it is provided that the container in which the thixotropic aluminum melt is produced is inserted into a collecting container for separating the liquid phase, in which the liquid phase flowing out of the discharge opening of the container is collected.

[0030] In one possible embodiment of the present invention, it is provided that the collecting container has a tapered shape.

[0031] According to a further aspect of the present invention, it is provided that the thixotropic aluminum melt is produced in a container, wherein the production of the thixotropic aluminum melt takes place with a first position of the container relative to the force of gravity, wherein in the first position a drain opening of the container, via which the liquid phase flows out of the container during the step of separating, is arranged on an upper side relative to the force of gravity.

[0032] In a possible embodiment of the present invention, it is provided that the insertion of the container into a centrifuge for separating the liquid phase from the container takes place with a second position of the container relative to gravity, which position is different from the first position.

[0033] In one possible embodiment of the present invention, it is provided that the container has a lid which forms a bottom region of the container when the aluminum melt is produced.

[0034] In one possible embodiment of the present invention, it is provided that the lid can be removed from the container to remove the solid phase from the container.

[0035] In a possible embodiment of the present invention, it is provided that the lid is arranged on a side opposite the drain opening of the container, through which the liquid phase flows out of the container during the separation step.

[0036] In one possible embodiment of the present invention, it is provided that the container has a tapered shape starting from the side which is closed by the lid during melting.

[0037] According to a further aspect of the present invention, the separation of the liquid phase is carried out via a sieve element whose openings are so small that the aluminum melt does not flow through the openings only by gravity and without the action of a centrifugal force.

[0038] In one possible embodiment of the present invention, it is provided that the openings have a diameter of less than 3 mm, preferably less than 2 mm.

[0039] In one possible embodiment of the present invention, the openings have a diameter of more than 0.01 mm, preferably more than 0.1 mm. The size of the holes depends on the magnitude of the centrifugal force used to separate the liquid phase, whereby the size of the holes can be reduced as the centrifugal force increases.

[0040] In one possible embodiment of the present invention, the diameter is preferably between 0.5 mm and 1 mm. This size has proven particularly useful when a centrifugal force of between 10 G and 30 G, in particular between 15 G and 25 G, is applied to the melt.

[0041] In a possible embodiment of the present invention, it is provided that the sieve element is inserted into a container in order to separate an upper region, in which the thixotropic aluminum melt is produced and in which the solid phase is retained during separation, from a lower region for receiving the liquid phase.

[0042] In one possible embodiment of the present invention, the sieve element is removed to remove the liquid phase. The liquid phase is preferably removed in the liquid state, i.e., without solidifying after separation. However, the liquid phase can also be allowed to solidify first in the container before being removed therefrom.

[0043] In one possible embodiment of the present invention, it is provided that the sieve element can be inserted into the container via an annular insert.

[0044] According to a further aspect of the present invention, it is provided that a retaining element which retains the solid phase while the liquid phase is separated is inserted into a collecting container which receives the liquid phase.

[0045] In a possible embodiment of the present invention, it is provided that the collecting container which receives the liquid phase has a shape which tapers towards its closed end.

[0046] In a possible embodiment of the present invention, it is provided that the solid phase is removed from the container in which the thixotropic aluminum melt was produced after the liquid phase has been separated and preferably after solidification.

[0047] In one possible embodiment of the present invention, the liquid phase is removed after the removal of the solid phase and / or the separation element, preferably in the liquid state. In particular, the solid phase and the separation element are therefore removed from the container first, followed by the liquid phase, with the removal of the liquid phase preferably taking place by pouring the liquid phase out of the container.

[0048] In a first possible embodiment of the present invention, it is provided that the retaining element is a further container in which the thixotropic aluminum melt is produced and which has at least one discharge opening for the liquid phase.

[0049] In a possible embodiment of the present invention, it is provided that the further container has a shape tapering towards a drain opening and / or is open on the side opposite the drain opening in order to remove the retained solid phase.

[0050] In a possible embodiment of the present invention, it is provided that the solid phase is removed after the liquid phase has been separated on a side opposite a discharge opening, which is closed by a lid during the production of the aluminum melt.

[0051] In a second possible embodiment of the present invention, it is provided that the retaining element is a sieve element which is inserted into the first container in order to separate an upper region for retaining the solid phase from a lower region for receiving the liquid phase.

[0052] In a possible embodiment of the present invention, it is provided that the solid phase, after separation of the liquid phase, is passed through a sieve element on an open side of the container, which is opposite a closed side in which the liquid phase is received.

[0053] In one possible embodiment of the present invention, it is provided that the container and / or the collecting container and / or the separating element and / or the sieve element has a ceramic coating and / or is made of ceramic.

[0054] In one possible embodiment of the present invention, the centrifugal force is generated by a centrifuge in which a container filled with the thixotropic aluminum melt is set in rotation.

[0055] In one possible embodiment of the present invention, it is provided that a centrifugal force of more than 5 G is generated, preferably more than 10 G. For example, a centrifugal force in a range between 10 G and 100 G can be generated.

[0056] In a possible embodiment of the present invention, it is provided that the cooling to the target temperature takes place at a rate between 0.1 K / sec and 2 K / sec.

[0057] In one possible embodiment of the present invention, it is provided that the container with the aluminum melt is arranged in a heated area for controlled cooling, in particular above a gas furnace.

[0058] In one possible embodiment of the present invention, the aluminum melt is held at the target temperature for a holding time, preferably between 1 second and 60 minutes. Preferably, the holding time is more than 10 seconds. In an alternative embodiment, however, a holding time can be omitted.

[0059] In one possible embodiment of the present invention, it is provided that the liquid aluminum melt has an initial temperature of more than 850°C.

[0060] In a possible embodiment of the present invention, it is provided that the liquid aluminum melt is filled into a container for controlled cooling, which, after cooling, is transferred to a centrifuge in which the liquid phase is separated.

[0061] The individual aspects of the present invention can be combined with one another. Furthermore, preferred features described for one aspect can also be used for the other aspects.

[0062] The present invention further comprises an apparatus for carrying out a method as described above, wherein the apparatus a device for producing an aluminium melt containing a liquid and a solid phase, and a device for applying a centrifugal force to the aluminium melt, in particular a centrifuge, and for separating the liquid phase by the action of a centrifugal force, includes.

[0063] According to the present invention, it is further provided that the device comprises a controller and actuators which are configured to carry out the method according to the invention.

[0064] In particular, the controller and actuators are configured for automated execution of the method. In particular, the controller is programmed to execute a method according to the invention. Preferably, the controller comprises a microprocessor and a memory in which a program with commands is stored, which, when executed on the microprocessor, cause the device to execute the method according to the invention.

[0065] In a possible embodiment of the present invention, it is provided that the device comprises a sieve element and / or a container with a drain opening, which can preferably be inserted into a container for receiving the liquid phase.

[0066] Preferably, the device is designed as already described in more detail above.

[0067] The present invention will now be described in more detail with reference to embodiments and drawings.

[0068] Showing: Fig. 1: A first embodiment of a method according to the invention with steps a to e and Fig. 2: A second embodiment of a method according to the invention with steps a to e.

[0069] According to the present invention, to deplete the iron content of aluminum, a thixotropic aluminum melt is first produced from the iron-containing aluminum, i.e., an aluminum melt with at least one liquid and solid phase. The present invention takes advantage of the fact that, upon cooling, solid iron phases initially form from the iron contained in the aluminum melt in a liquid aluminum melt, so that the iron content in the remaining liquid phase is reduced. The separation of the liquid phase from the solid phase according to the invention therefore produces aluminum with a reduced iron content.

[0070] In both embodiments, the solid phase is retained, and the liquid phase is extracted from the solid phase by the action of centrifugal force on the thixotropic aluminum melt. In particular, the solid phase is formed into a three-dimensional structure for this purpose. The solid phase in the thixotropic aluminum melt can be present either in the form of isolated Al-Fe phases, which interlock with one another during extraction of the liquid phase to form a sponge-like structure, or in the form of a three-dimensionally cross-linked structure, which is already present in a sponge-like manner in the thixotropic aluminum melt. In both cases, the retained solid phase and the extracted liquid phase can be removed separately.

[0071] In both embodiments, the solid phase remains in the container or container region in which the thixotropic aluminum melt was produced, while the liquid phase is separated into another container or container region. However, the two embodiments differ with regard to the correct process control and the separation element that retains the solid phase.

[0072] In the Fig. 1 In the illustrated embodiment, an extraction crucible 1 is used, into which a sieve 3 is inserted. In the specific embodiment, an annular insert 2 is provided for this purpose, over which the sieve element 3 is arranged in the extraction crucible 1. The sieve element 3 divides the extraction crucible 1 into an upper and lower region when inserted. The extraction crucible 1 tapers conically toward its bottom. The extraction crucible 1 in the empty state is shown in step a.

[0073] In step b, a liquid, iron-containing aluminum melt 4, which preferably has a temperature of over 850 °C, is poured into the upper region of the extraction crucible 1 above the sieve element 3.

[0074] The holes in the sieve element 3 are dimensioned such that the aluminum melt does not flow through the sieve element due to gravity alone. Rather, the surface tension of the aluminum melt prevents it from flowing through the holes in the sieve element. The holes preferably have a diameter between 0.5 mm and 1 mm. The sieve element 3 can be designed, for example, as a solid ceramic element or as a ceramic-coated metal plate. In the exemplary embodiment, the holes are adapted to a process in which a centrifugal force of 20 G is applied. At a higher centrifugal force, the holes can be selected to be smaller.

[0075] Next, in step c, the liquid aluminum melt is subjected to controlled cooling to convert it into a thixotropic state. In the thixotropic state, the aluminum melt 5 comprises both solid and liquid components. In particular, the thixotropic melt comprises an AlFe skeleton or AlFe particles or AlFe agglomerates as the solid phase, in and / or between which the liquid phase, which has a lower iron content, remains.

[0076] The controlled cooling preferably takes place at a rate of 0.1 to 2 Kelvin / sec. Cooling takes place to a target temperature, which depends on the iron content and other composition of the initial melt. According to the invention, the target temperature is between 575 and 655 °C. In an exemplary embodiment, the target temperature can be between 600 and 603 °C. Cooling preferably takes place in a furnace, for example, a forced-air furnace.

[0077] Once the thixotropic aluminum melt 5 has been produced in step c, the extraction crucible 1 is transferred to a centrifuge for extraction of the liquid phase. As shown in step d, a centrifugal force acts on the thixotropic melt 5 in a direction pointing toward the bottom of the extraction crucible. As a result, the liquid phase 7 flows through the openings in the sieve element 3 into the lower container area, while the solid phase 6 is retained and remains in the upper crucible area.

[0078] After the AlFe skeleton 6 and the depleted liquid phase 7 have solidified, both phases are removed separately from the extraction crucible 1 in step e. For this purpose, the solid phase 7 is first removed from the upper container region. After the sieve element 3 and the insert 2 have been removed, the liquid, depleted aluminum phase 7 can also be removed from the lower container region. The removal of the liquid, depleted aluminum phase 7 from the lower container region preferably takes place while it is still liquid, in particular by pouring it out of the container. Alternatively, however, the liquid phase could also solidify in the container and be removed in the solidified state.

[0079] The Fig. 1 The embodiment used can also be used when the solid phase 6 does not have a stable structure, since it is supported and retained by the sieve element. It is therefore particularly used when the solid phase 6 in the thixotropic aluminum melt is present in the form of isolated globular or agglomerated Al-Fe phases, or the three-dimensionally cross-linked, sponge-like structure does not have sufficient strength.

[0080] Fig. 2 shows a second embodiment of a method according to the invention, which can be used in particular when the solid phase 6 is produced in such a way that it has a stable, self-supporting structure.

[0081] Here, an extraction crucible 1 with a removable bottom lid 2 is used, as shown in step a. A drainage opening 3 is located on the side opposite the bottom lid 2. The extraction crucible 1 tapers conically toward the drainage opening 3, with an edge region of the bottom opposite the bottom lid 2 surrounding the drainage opening 3 in a collar-like manner.

[0082] As shown in step b, the extraction crucible 1 with the bottom lid 2 in place is arranged so that the outlet opening 3 is at the top and the opposite opening, closed by the bottom lid 2, is at the bottom. The extraction crucible 1 is then filled via the outlet opening 3 with a liquid aluminum melt, which in turn preferably has a temperature of more than 850 °C. In this state, the bottom lid 2 therefore forms the bottom of the extraction crucible, while the outlet opening 3 serves as the inlet opening.

[0083] The liquid aluminum melt 4 is now cooled in step c. The cooling process takes place in the same manner as described above with regard to the first embodiment. Through controlled cooling, a thixotropic melt 5 is created in the extraction crucible 1. The solid phase preferably forms in the form of a solid sponge of Fe-rich phases, which remains essentially unchanged even during the subsequent centrifugal process.

[0084] For the centrifugal extraction in step d, the extraction crucible 1 is now placed into a collecting container 8 with the drain opening 3 facing downwards.

[0085] The collecting container 8 is also conical and dimensioned such that a second container area is created in the collecting container 8 below the extraction opening 3 of the extraction crucible 1 inserted into the collecting container, into which the liquid phase of the thixotropic aluminum melt can flow.

[0086] To insert the extraction crucible 1 into the collecting container 8, the extraction crucible 1 is therefore rotated by 180 °C so that the drain opening 3 is on the underside and the bottom lid 2 is on top, thus forming a lid area.

[0087] Centrifugation then occurs in such a way that the centrifugal forces act from the extraction crucible 1 through the outlet opening 3 into the lower region of the collecting container 8. The solid phase 6 is retained in the extraction crucible 1, while the liquid phase flows into the region of the collecting container 8 remaining below the extraction crucible 1 due to the effect of the centrifugal force.

[0088] After the solid phase 6 and the liquid phase 7 have solidified, they are removed as shown in step e. For this purpose, the extraction crucible 1 is first removed from the collecting container 8 and, after opening the bottom lid 2, the AlFe sponge 6 is removed. The liquid phase 7 containing depleted aluminum is removed from the lower region of the collecting container 8. The removal of the liquid, depleted aluminum phase 7 from the lower container region is again preferably carried out while it is still liquid, in particular by pouring it out of the container. Alternatively, however, the liquid phase could also solidify in the container and be removed in the solidified state.

[0089] The elements used in the two embodiments which come into contact with the melt, ie in particular the extraction crucible 1, the insert 2, the sieve element 3 and / or the collecting container 8, preferably have a ceramic coating and / or are made of ceramic.

[0090] The solid Al-Fe phases produced in the present invention must be such that the liquid Al can be "expelled" in high proportions.

[0091] The morphology of these phases is crucial for this. If, for example, isolated plates are formed, they lie perpendicular to the outflowing Al and block the Al's path, resulting in inadequate separation. The same thing happens if a 3D sponge is created, but it breaks apart due to centrifugal forces.

[0092] Therefore, centrifugal phase separation requires either isolated and as large as possible Al-Fe phases or a stable sponge. Both cases can be specifically adjusted by controlling phase formation during demixing.

[0093] For the first embodiment of the Al-Fe phase in the form of isolated and as large as possible Al-Fe phases, the first embodiment is preferably used, while for the sponge solution the second embodiment is preferably used.

[0094] Isolated phases can be present in the form of globular particles or as sponge agglomerates that are initially unconnected. In both cases, they are retained and entangled on the filter screen without blocking the flow paths.

[0095] The sponge solution preferably produces Al-Fe plates that grow together. These form a coral-like structure. The purified Al can then flow through these plates without breaking the sponge structure or being carried away by the melt.

[0096] Both embodiments thus enable effective iron depletion from an aluminum melt and utilize the properties of the thixotropic aluminum melt to separate the liquid phase from the solid phase.

[0097] The first embodiment is preferably used for the depletion of aluminum with an already relatively low iron content of, for example, less than 2 wt.% or 1 wt.%, e.g., for a reduction of the Fe concentration from 0.7 to 0.3 wt.%. In this range, stable sponges do not form; instead, 3D skeletons are formed that break during centrifugation, or isolated islands with Fe phases form. Therefore, during centrifugation, the Fe phases migrate along with the residual melt. The sieve element retains these solid phases and allows the melt to pass through. A filter cake of Fe-rich phases is formed above the sieve element.

[0098] The second embodiment is preferably used for the depletion of aluminum with a higher iron content of, for example, more than 2 wt.%, e.g., with an iron content of 2 to 5 wt.%. With appropriate process control, a solid sponge of Fe-rich phases forms, which remains essentially unchanged even during the centrifugal process, so that a sieve element can be dispensed with.

Claims

1. Method for at least partially removing iron from an aluminum melt, comprising the steps of: - Producing a thixotropic aluminum melt containing a liquid phase and a solid phase, wherein the thixotropic aluminum melt is produced by cooling a liquid aluminum melt to a target temperature in a controlled manner, and - separating the liquid phase by the effect of a centrifugal force on the thixotropic aluminum melt, wherein the target temperature is in the range of 575 °C to 655 °C.

2. Method according to claim 1, wherein the solid phase is retained and the liquid phase is separated by application of the centrifugal force, wherein the solid phase preferably remains in a container or container area in which the aluminum melt is produced and is preferably subsequently removed therefrom, wherein the solid phase is preferably formed in the form of a 3-dimensionally crosslinked, in particular sponge-like structure and / or as particles and / or agglomerates which are supported on one another during separating the liquid phase.

3. Method according to claim 1 or 2, wherein a retaining element is used, which retains the solid phase while the liquid phase is separated.

4. Method according to claim 3, wherein the retaining element is a container in which the thixotropic aluminum melt is produced with a solid phase and a liquid phase, and which comprises at least one discharge opening for the liquid phase, wherein the container preferably has a shape tapering in the direction of a discharge opening and / or is open on the side opposite the discharge opening, for removing the retained solid phase, wherein preferably the container in which the thixotropic aluminum melt is produced is inserted into a collecting container for separating the liquid phase, in which the liquid phase flowing out of the discharge opening of the container is collected, wherein the collecting container preferably has a tapering shape.

5. Method according to any one of the preceding claims, wherein the thixotropic aluminum melt is produced in a container, and wherein the production of the thixotropic aluminum melt takes place with a first position of the container relative to gravity, wherein in the first position, a discharge opening of the container, via which the liquid phase flows out of the container during the separation step, is arranged on an upper side relative to gravity, wherein preferably the insertion of the container into a centrifuge for separating the liquid phase from the container takes place with a second position of the container, which is changed compared to the first position, relative to gravity.

6. Method according to any one of claims 4 or 5, wherein the container comprises a lid which forms a bottom region of the container when the molten aluminum is produced and / or which can be removed from the container in order to take out the solid phase from the container, wherein preferably the lid is arranged on a side opposite the discharge opening of the container via which the liquid phase flows out of the container during the separation step and / or wherein the container has a tapering shape starting from the side which is closed by the lid during melting.

7. Method according to any one of the preceding claims, wherein the separating the liquid phase takes place via a sieve element, the openings of which are so small that the molten aluminum does not flow-off through the openings only by gravity and without the action of a centrifugal force, wherein preferably the openings have a diameter of less than 3 mm, preferably of less than 2 mm, and / or wherein preferably the openings have a diameter of more than 0.01 mm, preferably of more than 0.1 mm, wherein the diameter is further preferably between 0.5 mm and 1 mm.

8. Method according to claim 7, wherein the sieve element is inserted into a container to separate an upper region, in which the thixotropic aluminum melt is produced and in which the solid phase is retained during separation, from a lower region for receiving the liquid phase, wherein the sieve element is preferably removed to remove the liquid phase, preferably after solidification thereof.

9. Method according to any one of the preceding claims, wherein a retaining element, which retains the solid phase while the liquid phase is separated, is inserted into a collecting container which receives the liquid phase, wherein preferably the collecting container which receives the liquid phase has a shape tapering towards its closed end.

10. Method according to claim 9, wherein the retaining element is a sieve element which is inserted into the first container in order to separate an upper region for retaining the solid phase from a lower region for receiving the liquid phase, and / or wherein the retaining element is an additional container in which the aluminum melt is produced with a solid phase and a liquid phase and which comprises at least one discharge opening for the liquid phase, wherein the additional container preferably has a shape tapering in the direction of a discharge opening and / or is open on the side opposite the discharge opening for removing the retained solid phase.

11. Method according to any one of the preceding claims, wherein the container and / or the separating element and / or the collecting container and / or the sieve element comprises a ceramic coating and / or is made of ceramic material and / or wherein the centrifugal force is generated via a centrifuge in which a container filled with the thixotropic aluminum melt is induced to rotation.

12. Method according to any one of the preceding claims, wherein the solid phase, after separating the liquid phase and preferably after solidification, is removed from the container in which the thixotropic aluminum melt was produced, in particular on a side opposite a discharge opening which is closed by a lid when the thixotropic aluminum melt is produced, or on an open side of the container, which is opposite a closed side in which the liquid phase is received, via a sieve element, and / or wherein the liquid phase is removed after removal of the solid phase and / or the separating element, preferably in the liquid state.

13. Method according to any one of the preceding claims, wherein the cooling takes place at a rate of between 0.1 K / sec and 2 K / sec, and wherein the molten aluminum is preferably held at the target temperature for a holding time, wherein the holding time is preferably between 1 second and 60 minutes, and / or wherein the molten liquid aluminum has an initial temperature of more than 850 °C, and / or wherein the molten liquid aluminum is filled into a container for controlled cooling, which container, after cooling, is transferred into a centrifuge in which the liquid phase is separated-off.

14. Device for carrying out a method according to any one of the preceding claims, wherein the apparatus comprises - a device for producing a thixotropic aluminum melt including a liquid phase and a solid phase, and - a device for applying a centrifugal force to the thixotropic aluminum melt, in particular a centrifuge, and for separating the liquid phase by the action of a centrifugal force, wherein the device comprises a controller and actuators which are configured to perform the method according to any one of the preceding claims.

15. Device according to claim 14, wherein the device comprises a controller and actuators which are configured for automatically carrying out the method, and / or wherein the device comprises a sieve element and / or a container with a discharge opening, which is preferably insertable into a container for receiving the liquid phase.

Images