METHOD FOR OBTAINING A REFRACTORY METAL

Abstract

A process is provided for recovering a refractory metal. A comminuted precursor material includes the refractory metal to be recovered in oxidically bound form. A reactant of loose solids includes a slag former having a higher O.sub.2 affinity than the refractory metal. A heat-resistant reaction vessel is filled with a charge of a mixture of the precursor material and the reactant. The process triggers an exothermic redox reaction of the charge, while an inertia force acts on the reaction vessel. The charge is melted, whereby the molten refractory metal and the slag are separated owing to the inertia force that acts on the vessel during the exothermic redox reaction. The reaction vessel with at least the reaction products is cooled. Reaction products are removed from the reaction vessel, and the refractory metal is separated from the slag.

Claims

1. A process for recovering a refractory metal, in which the refractory metal is recovered from a precursor material by a redox reaction which is exothermic in terms of its energy balance, the process comprising: providing a comminuted precursor material comprising the refractory metal to be recovered in oxidically bound form; providing a reactant that reacts exothermically after ignition as reactant loose solids, wherein the reactant comprises a slag former having a higher O.sub.2 affinity than the refractory metal to be recovered; providing a loose solids/material mixture from the comminuted precursor material and the reactant; filling a heat-resistant reaction vessel with a charge of the loose solids/material mixture, leaving a pore volume; reducing the pore volume of the charge by compacting the charge by introduction of mechanical vibrations; applying an inertia force that acts on the reaction vessel with contents of the reaction vessel; triggering the exothermic redox reaction of the charge while the inertia force is acting thereon by a local supply of thermal energy to the charge, beginning from an edge of the charge, hence melting the refractory metal to be recovered and separating molten refractory metal from slag owing to the inertia force that acts during the exothermic redox reaction; ending the inertia force that acts on the reaction vessel and the contents of the reaction vessel after the redox reaction has concluded; and cooling the contents of the reaction vessel and then removing reaction products from the reaction vessel and separating recovered refractory metal from the slag.

2. A process for recovering a refractory metal, in which the refractory metal is recovered from precursor material by a redox reaction which is exothermic in terms of its energy balance, the process comprising: providing a comminuted precursor material comprising the refractory metal to be recovered in oxidically bound form; providing a reactant that reacts exothermically after ignition as reactant loose solids, wherein the reactant comprises a slag former having a higher O.sub.2 affinity than the refractory metal to be recovered; providing a loose solids/material mixture from the comminuted precursor material and the reactant; filling a heat-resistant reaction vessel with a charge of the loose solids/material mixture, leaving a pore volume; applying an inertia force that acts on the reaction vessel with contents of the reaction vessel; triggering the exothermic redox reaction of the charge while the inertia force is acting thereon by a local supply of thermal energy to the charge, beginning from the an edge of the charge, hence melting the refractory metal to be recovered and separating molten refractory metal from slag, which is at least partly molten as a result of the input of heat, owing to the inertia force that acts during the exothermic redox reaction; ending the inertia force that acts on the reaction vessel and the contents of the reaction vessel after the redox reaction has concluded; and cooling the contents of the reaction vessel and then removing reaction products from the reaction vessel and separating molten refractory metal from the slag.

3. The process as claimed in claim 2, wherein filling of the reaction vessel with the charge of the loose solids/material mixture is followed by reducing the pore volume of the charge by compaction thereof by introduction of mechanical vibrations.

4. The process as claimed in claim 1, wherein the precursor material for provision of the comminuted precursor material is comminuted to a grain size between 10 m and 500 m.

5. The process as claimed in claim 1, wherein the reactant has a grain size between 50 m and 500 m.

6. The process as claimed in claim 1, wherein the loose solids/material mixture is provided by mixing the comminuted precursor material and the reactant in a closed mixing vessel.

7. The process as claimed in claim 1, wherein the charge after the reducing of the pore volume is left with a pore volume of 10% to 30% in the reaction vessel before being subjected to the subsequent process steps.

8. The process as claimed in claim 1, wherein the charge is introduced into the reaction vessel in a grading with regard to different constituents of the charge.

9. The process as claimed in claim 1, wherein the inertia force applied to the reaction vessel is less than 350 G.

10. The process as claimed in claim 9, wherein the inertia force is applied using a centrifuge having multiple reaction vessel holders in pairs arranged diametrically opposite one another with regard to an axis of rotation.

11. The process as claimed in claim 1, wherein the exothermic reaction is triggered by a resistance heating element and/or by a laser beam.

12. The process as claimed in claim 1, wherein the reaction vessel, in a section in which the molten refractory metal collects during the exothermic redox reaction, simultaneously serves as an originally forming collecting volume for the refractory metal to be recovered in which the molten refractory metal hardens, forming a casting of a cavity of the collecting volume.

13. The process as claimed in claim 12, wherein the reaction vessel is filled such that, rather than the collecting volume which is connected thereto and is provided for collection of the molten metal being filled with the loose solids/material mixture, only a volume present in a direction of an introduction opening is filled, with the collecting volume kept clear using a loose solids/material mixture barrier that allows the molten refractory metal through for separation of the charge from the collecting volume.

14. The process as claimed in claim 13, wherein the loose solids/material mixture barrier comprises a heat-resistant material.

15. The process as claimed in claim 13, wherein the loose solids/material mixture barrier comprises a metal which is also present in the refractory metal to be recovered or comprises the refractory metal to be recovered.

16. The process as claimed in claim 1, wherein the reactant is simultaneously the slag former.

17. The process as claimed in claim 1, wherein the reactant comprises a slag former.

18. The process as claimed in claim 1, wherein the reactant includes one or more elements from a group of elements consisting of Al, Mg and Si.

19. The process as claimed in claim 1, wherein the exothermic redox reaction of the charge is triggered in different places in the reaction vessel.

20. The process as claimed in claim 6, wherein the loose solids/material mixture is provided by mixing the comminuted precursor material and the reactant in the closed mixing vessel without introducing energy into the material to be mixed.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Subject matter of the present disclosure will be described in even greater detail below based on the exemplary FIGURES. All features described and/or illustrated herein can be used alone or combined in different combinations. The features and advantages of various embodiments will become apparent by reading the following detailed description with reference to the attached drawings, which illustrate the following:

[0010] FIG. 1 illustrates a flow diagram of steps of a process for obtaining a refractory metal according to an embodiment of the invention.

DETAILED DESCRIPTION

[0011] Proceeding from the prior art discussed above, in an embodiment, the present invention provides a process that has been simplified compared to the conventional industrial route for recovery of refractory metals or metal alloys and is especially also suitable for industrial metallurgical recovery of metals, which additionally avoids, or at least distinctly reduces, the disadvantages detailed in the prior art discussed above.

[0012] The word metal used in the context of these details includes transition metals and metal alloys alike. The details that follow are thus equally applicable to direct recovery of metals, transition metals and metal alloys.

[0013] The word refractory used in the context of these details, referring to a metal or a metal alloy, means those substances that have a melting temperature of at least 900 C.

[0014] FIG. 1 shows comminution of an ore and a reactant according to an embodiment. In the process according to an embodiment, the precursors for formation of the loose solids/material mixture to be introduced into a reaction vessel are prepared independently. The material from which the metal is to be recovered, if it does not have the desired grain size or particle size by nature, is comminuted. A target grain size of the precursor material between 10 and 500 m is envisaged. This material is preferably comminuted such that it has quite a narrow distribution spectrum in terms of its particle size distribution. It is of interest for the process of an embodiment that the grain size of the precursor material can be larger by one or even more than two orders of magnitude compared to the specifications from CN 105132724 B. The comminution intensity to be applied is correspondingly smaller. The same also applies to the provision of the reactant. The target grain size of the reactant which is typically envisaged is in the range between 50 m and 500 m and can therefore be processed in a hazard-free manner with the customary safety precautions. The treatment steps that are necessary with regard to the desired target grain size of the precursor material and of the reactant are performed independently, such that each comminution step can be matched to the material to be comminuted. This is also true of the machines used for comminution. For the provision of the reactant in the desired grain size in particular, comminution irrespective of the precursor material is advantageous since it is sometimes necessary for the reactant to be comminuted with a greater degree of care. Moreover, the treatment steps envisaged for comminution are fundamentally conducted in dry form, such that there is no need to dry any of these precursors.

[0015] A material mixture is introduced into a reaction vessel as loose solids. Because of this property, the cavity of the reaction vessel is filled over its cross section, irrespective of its cross-sectional geometry and cross-sectional size. This means that the cavity provided by the reaction vessel can be filled as best possible with regard to its cross section, and the cavity can be utilized optimally for introduction of the material mixture. The introduction of the loose solids/material mixture into the reaction vessel, according to the first provided solution, is followed by a step of compacting the loose solids/material mixture introduced into the reaction vessel, in order to reduce the pore volume. Typically, the pulverulent material mixture introduced into the reaction vessel will have a pore volume which is still too large for the intended purposes. Such compaction is effected by introducing mechanical vibrations into the reaction vessel, acting on its contents. This operation can be implemented, for example, on an agitator plate. In the case of larger reaction vessels, it is also provided to use other agitators.

[0016] The above-described operation of compacting the loose solids/material mixture introduced into the reaction vessel means that the progress of the exothermic reaction is much better controllable. For that reason, the process claimed is scalable, meaning that it is also usable directly on an industrial scale.

[0017] In an embodiment, the loose solids/material mixture introduced into the reaction vessel is compacted in two stages to reduce its pore volume. A first compaction step is conducted with a lower frequency and lower agitation force compared to the second compaction step. Depending on the loose solids/material mixture present in the reaction vessel, the first compaction step is conducted, for example, with a frequency of 40 to 65 Hz and agitation force of 300 to 500 N/kg, based on the total weight. The second compaction step will be able to be conducted with a frequency of 80 to 180 Hz and an agitation force of 450 to 800 N/kg in relation to the total weight. In these compaction steps, sinusoidal oscillations are typically introduced into the loose solids/material mixture, or into the reaction vessel containing the loose solids/material mixture. In such a two-stage compaction of the loose solids/material mixture, the second compaction step will be made longer in terms of its duration than the first compaction step, such that it is 1.5 to 2.5 times longer, for example, than the first compaction step. For example, the duration set for the first compaction step can be a duration of 8 to 12 and especially about 10 min, and that for the second compaction step a duration of 17 to 25 and especially about 20 min.

[0018] Compaction of the material mixture introduced into the reaction vessel by application of higher compression forces is not ruled out in this process, but is not beneficial, especially since it cannot be ensured in the case of such a compaction that the material mixture will form a uniform pore volume over the fill height in the reaction vessel. In order to have better control over the surface material of the material mixture present in the reaction vessel in the case of agitation treatment, and in order to bring about a certain degree of compaction in this region too, such a compaction can also be combined with a pressing operation performed with low force, for instance by means of a ram that acts on the surface with low pre-tension, which tracks the decreasing fill height in the reaction vessel as a result of such a compaction process, or by virtue of which a uniaxial force acts on the loose solids/material mixture during the compaction process. This force is, for example, between 5 N/kg and 40 N/kg, where the weight relates to the weight of the loose solids/material mixture used and introduced into the reaction vessel. This force applied, which acts uniaxially on the loose solids/material mixture in the reaction vessel, is also dependent on the geometry of the reaction vessel, especially also the diameter thereof. In order to achieve the same degree of compaction in a reaction vessel of greater diameter as in a reaction vessel of smaller diameter, a correspondingly higher force is required. Such a force acting uniaxially on the loose solids/material mixture, in a design of the process with a two-stage compaction, is preferably applied only during the second compaction step. The remaining porosity of the material mixture in the reaction vessel should not be less than 20%. It is also provided to control the burnoff rate via the porosity of the loose solids/material mixture. A pore volume of more than 45% to 50% is not considered to be viable. The pore volume within the loose solids/material mixture is used as a liquid pathway to allow the molten metal to flow to the base of the reaction vessel as a consequence of the inertia force acting thereon after triggering of the exothermic reaction for melting of the metal to be recovered.

[0019] In a next step, the reaction vessel with its contents is subjected to an inertia force. This is typically effected by placing the reaction vessel in a centrifuge. Significantly lower inertia forces are required for this method, which are well below the order of magnitude specified for recovery of a TiAl alloy in CN 105132724 B. These are generally well below 350 G. In many cases, an inertia force of 80 to 170 G is entirely sufficient to be able to perform the desired physical separation within the reaction vessel. Since there is a remaining pore volume for the separation of the molten metal from the slag in the material mixture, and the pore size is correspondingly large because of the grain size of the particles of the material mixture, even relatively small inertia forces are sufficient to implement effective separation of the molten metal from the slag.

[0020] The exothermic reaction process is triggered by means of local heating of the loose solids/material mixture. For this purpose, a heat-resistant ignition wire, for example a tungsten wire, can be used disposed on or adjacent to the material mixture in the reaction vessel. The exothermic reaction in the loose solids/material mixture can also be triggered by a laser beam that hits the surface of the material mixture in the reaction vessel. In many cases, the exothermic redox reaction of the loose solids/material mixture will be triggered on its opposite side from the inertia force. The passage of the heat front formed by the triggering operation then follows in the direction of the inertia force. It is also provided that the exothermic reaction is triggered at several places in the loose solids/material mixture, where, in such a case, the triggering can be undertaken simultaneously or else in a time-delayed manner. The way in which the exothermic reaction of the loose solids/material mixture is triggered and, if triggering in several places is envisaged, whether this reaction is triggered in one or more places simultaneously or in a time-delayed manner is dependent on the desired progression of this redox reaction. This is dependent on the grain size of the reactant, the pore volume, the cavity geometry of the reaction vessel and the size thereof. The porosity of the molten material can also be influenced by the progression of the redox reaction and the migration of the heat front through the material mixture in the reaction vessel. The exothermic reaction of the loose solids/material mixture is triggered while the inertia force applied is acting thereon.

[0021] According to an embodiment, the loose solids/material mixture is heated by the exothermic reaction to such an extent that both the metal to be recovered and, at least to some degree, the slag as well are melted. The metal to be recovered is then separated from the slag in the liquid state, at least to the extent that the slag is molten. The separation of the two components from one anothermetal to be recovered and slagis then particularly good, with the outcome that the metal recovered is generally entirely free of inclusions. In a skillful manner, this measure exploits the higher contrast in density between these two components if they are each in the liquid state. The density of a substance in the liquid phase is regularly lower than in the solid-state phase. Consequently, the contrast in density between the molten metal and the slag, if the latter is likewise at least partly, preferably largely or even completely in the liquid state, is greater than when it is not molten and is in the solid state. Amplification of the contrast in density between the heavy metal to be recovered and the lighter slag to be separated therefrom can be performed in order to achieve the desired result of the separation process with a relatively small inertia force acting on the reaction vessel. This is a further step, which is independent at first from the step of compaction of the loose solids/material mixture introduced into the reaction vessel, in order to execute this process in a scalable manner. Preferably, the above-described embodiments will be combined with one another for performance of the process.

[0022] It is thus also made possible to influence the quality of the molten metal via the degree of liquefaction of the slag. Even though melting of the slag is particularly advantageous overall, equally good results can be effectively achieved when only 70% to 80% of the slag is molten. In this connection, it should be noted that even small liquefied slag contents have a favorable effect on the quality of the separation process. In an embodiment, the melting reaction is conducted in such a way that 25% to 30% of the slag is melted by the heat input.

[0023] The inertia force acting thereon during the course of the exothermic reaction results in particularly good separation of the molten metal from the slag, even if the slag is not melted, but better separation when both phases are in their liquid state, which results in formation of layering in the reaction vessel, in which the metal recovered is in the section adjoining the base of the reaction vessel and the slag above it. The molten metal is collected in a collecting volume. This can be the section adjoining the base of the reaction vessel. The collecting volume can be provided by a collecting vessel connected to the reaction vessel. The collecting volume can simultaneously be utilized as original mold in which the molten metal solidifies. By virtue of this process, in a single melting step, a semifinished product or casting, especially also one having complex geometry, can be produced from the precursor material in a single melting step in an embodiment. Such a semifinished product or such a casting can have different shapes. Even undercuts can be produced in this way, if the section of the collecting volume in which the metal recovered is present is openable to remove the hardened metal. Collecting volumes that are destroyed to remove the hardened metal (of the semifinished product or casting) can also be used. In such a case, the mold can be a clay mold, which is then replaced by a new one for the next melting process. If part of the reaction vessel is such an original mold as collecting volume, complete filling thereof by the molten metal will be ensured by making the cross-sectional area thereof smaller than that of the section above it toward the reaction vessel opening. The slag is then present in the region of the reaction vessel that follows the casting mold. In the case of formation of such a reaction vessel with an original mold, whether for production of a semifinished product or casting of complex geometry, a filling of the reaction vessel can be provided such that the collecting volume is not filled with the loose solids/material mixture, but rather only the section above it in the direction of the introduction opening. For example, a screen manufactured from a heat-resistant wire can be used in order to release the original molding on filling of the reaction vessel. In another working example, a metal foil is also provided for separation of the antechamber of the reaction vessel into which the loose solids/material mixture is introduced from the adjoining original mold. This preferably comprises a metal which is also present in the metal to be recovered. If, for example, an Ni alloy is being recovered by this method, an Ni foil will appropriately be used. If the alloy to be recovered contains Al, for example, an Al foil can be used for separation of the antechamber from the original mold. These foils are likewise melted when the metal is melted and are then part of the alloy. What is advantageous here is that, in the course of the process, no slag is generated in the original mold, which would have to be separated therefrom owing to the inertia force applied. This shortens the process time. Such semifinished products can, for example, be bars or else hollow bars.

[0024] It would also be entirely possible for several original molds to be connected to or to be part of such a reaction vessel as collecting volumes, into which the molten metal flows on account of the inertia force acting thereon. Especially when relatively small semifinished products or workpieces are required, several of these can be provided in a single melting process.

[0025] In the above-described process, it is also possible to provide several different comminuted precursor materials if the intention is to melt not an elemental metal but an alloy as metal to be recovered. It is also possible to add recycling material (recycling scrap) to the precursor material. This can be alloy-forming material. In another process configuration, the reactant contains one or more alloy elements which are either in elemental form or else in bound form and with which the metal to be recovered from the precursor material enters into a compound. This is advantageous specifically in the case of refractory metals. In this way, Ti, Ni, Cr and other refractory alloys can be produced effectively with any alloy elements in a single melting process, driven by the stipulated exothermic reaction.

[0026] The loose solids/material mixture introduced into the reaction vessel can be in graded form in the reaction vessel. Such grading is typically effected in the direction of the inertia force acting on the metal in the course of melting thereof. This can, for example, be a different mixing ratio of individual components present in the loose solids/material mixture, and likewise inhomogeneous arrangement of particular precursor materials or admixtures over the height of the reaction vessel in the loose solids/material mixture. Since metal is recovered by a direct route by this process, this process can likewise be used to create a graded material in a simple manner.

[0027] Depending on the size of the reaction vessel, especially the height or extent thereof in the direction of the inertia force acting thereon and the volume of the loose solids/material mixture, the exothermic reaction process is performed within a relatively short time. Depending on the aforementioned circumstances, such a process can already be complete within a few tens of seconds. Even in the case of larger volumes of the loose solids/material mixture, a reaction time of only a few minutes is required. This calculation has to include the melting of the metal(s) and the crystallization (hardening) thereof. The fact that the inertia force acting on the reaction vessel with its contents during the reaction process causes the desired separation of molten metal and slag to be complete over the entire extent of the reaction vessel in the direction of the inertia force acting thereon has to be included in the burnoff time and the migration of the heat front through the loose solids/material mixture. This flow zone of the molten metal leads simultaneously to homogenization of the melt, which is significant particularly when a metal alloy composed of different precursor materials is to be melted. In one configuration of the method, the reaction vessel should be equipped with a thermal insulation effect in order that the heat generated by the exothermic reaction therein remains in the reaction vessel for longer than the reaction that actually proceeds, at a temperature level at which the metal to be recovered has not yet hardened. It is thus possible by this process to increase the recovery rate from the precursor material used.

[0028] The reaction vessel is typically inert in relation to the elements or compounds present in the loose solids/material mixture. It is typically undesirable for elements to be leached out of the reaction vessel in the course of the exothermic reaction process and introduced into the melt.

[0029] The relatively low inertia force which is envisaged in this process compared to previously known processes makes this process scalable, especially also to the effect that the amount of metal to be recovered with each charge can be sufficiently large for economically viable exploitation of this process. With the above-described forces, it is entirely possible to produce samples in a reaction vessel of several tens of kilograms or even a few hundred kilograms. It is also entirely possible to use reaction vessels with which semifinished products or else castings of relatively high weight can be produced.

[0030] A special feature in this process is that the metal recovery process can be influenced by two crucial control parameters, specifically the temperature triggered by the exothermic reaction and the inertia force. The temperature of the molten metal can influence the viscosity thereof. In principle, in the case of relatively low viscosity of the molten metal, only a relatively low inertia force is required for the separation process. The temperature and the inertia force for the metal melting and separation process are determined depending on the metal to be recovered and also on the design of the part of the reaction vessel into which the molten metal is to flow:

[0031] Depending on the metal, different temperatures are required for the melting of the metals from the oxides used as raw material. The exothermic process used for the melting of the metals or the metal alloys can be influenced by physical parameters, for example the particle size of the comminuted precursor material, the inertia force acting on the loose solids/material mixture, the degree of compaction or the pore volume set up, and the design of the reaction vessel. The smaller the particle size, the shorter the time taken to recover the metal to be melted therefrom. The inertia force can likewise influence the speed of migration of the heat front through the loose solids/material mixture within the reaction vessel, in the same way as the reaction temperature. In the case of higher inertia forces, the heat front migrates more quickly through the loose solids/material mixture. Higher inertia forces affect the reaction temperature when they are provided by centrifuges, as is likely to be the case regularly, since the cooling effect brought about thereby is greater at higher speeds.

[0032] The intensity and duration of the exothermic reaction at the individual particles can be influenced by the degree of compaction, and likewise by the transport velocity with which the molten metal flows into the collecting volume. The size and design of the collecting volume provided for collection of the liquid melt influences the cooling rate or cooling curve of the molten metal collected therein. It can be the case that the collecting volume and the loose solids/material mixture introduced into it are preheated, for example to a temperature between 500 C. and 600 C., before the exothermic reaction is started. The molten metal fractions that are collected first therein are then cooled at a correspondingly slower rate at the preheated inner wall of the vessel used as collecting volume, with the result that the crystal structure of the collected metal is more uniform overall.

[0033] The metal recovery process can also be influenced by the composition of the reactant or by admixtures, and hence in a chemical manner. For example, it can contain oxides, by which the reaction temperature is elevated or else lowered. Other reactant constituents can be utilized to delay the exothermic reaction. For example, it is possible to use admixtures that can increase or lower the melting temperature of the slag. Substances used for such purposes, generally oxides, are typically inert in relation to the metal to be recovered. CaO can be used to increase and MgO to lower the slag melting temperature. CaO will be used when a metal having a relatively low melting temperature is to be recovered. If the melting temperature of the slag is lower than the melting temperature of the metal to be recovered, it is possible to use MgO to increase the slag melting temperature.

[0034] Energy control with regard to the progression of the melting reaction in the reaction vessel also involves the particle size of the precursor material and of the reactant. The smaller the grain size, the faster the reaction will proceed for each particle. In this respect, the reaction of substance mixtures that react in a particularly exothermic manner can be delayed by provision of a relatively large particle size. A relatively large particle size has a positive effect on the upstream comminution processes since these can be performed in a correspondingly shortened manner. The particle size is thus also utilized in a skillful manner for energy control.

[0035] The above-described factors ensure scalability of the process, such that it can be performed even with relatively large batches, for example 10 to 200 kg, in a controlled manner and in particular also with uniform results.

[0036] The above details make it clear that an embodiment of this process differs from recovery processes that are in current industrial use not only by its much smaller number of process steps but in particular also by the considerable improvement in energy efficiency caused thereby. In addition, it is possible to better utilize the potential of the ore used as precursor. Moreover, emissions, in particular CO.sub.2 emissions, are significantly lowered. With regard to the use of energy, for example, with regard to the production of Ni recovery, energy use has been reduced to about 20%, and CO.sub.2 emissions to about 30%. The same also applies correspondingly to other alloys.

[0037] Embodiments of the invention are elucidated in detail hereinafter by a working example with reference to the flow diagram in FIG. 1. There follows a description of the use of the process of an embodiment for direct recovery of an Alloy 600 alloy (EN 2.4816). The process is used to produce an NiCrFe alloy of the following composition: Cr 15% by weight, Fe 8% by weight, balance: Ni, and also unavoidable impurities in a total amount of less than 1%. This is an alloy also known by the Alloy 600 name (EN 2.4816).

[0038] The crucial starting materials used are NiOCr2O3 and Fe2O3. In this working example, these are collectively comminuted to a grain size of about 85 m (step 1). The reactant used in this working example is Al. It is equally also possible to use Mg, Si or mixtures, typically together with a conventional flux thereof, as reactant. The precursor in this regard is comminuted to a grain size of 70 m (likewise step 1). In a subsequent stepprocess step 2the precursor and the reactant are mixed with one another. An industrial mixing machine is used for the purpose. The mixing process is executed in order that the mixing introduces a minimum amount of energy into the material being mixed. Both the comminuting operation and the mixing operation are performed dry.

[0039] Subsequently, the loose solids/material mixture taken from the mixture is introduced into a reaction vessel 1 (step 3). The reaction vessel 1 shown in the FIGURE should be regarded merely as an illustrative execution of a reaction vessel in terms of its design. The reaction vessel 1 comprises a lower section 2 designed as an original mold. In this part of a section, the alloy hardened as a cast block is present at the end of the recovery process. The lower section 2 merges into an upper section 4 in the direction toward the introduction opening 3 of the reaction vessel 1. In terms of its diameter, this is greater than the diameter of section 2 which is utilized as the original mold. After the reaction vessel 1 has been filled, the loose solids/material mixture present therein is compacted on an agitator plate (step 4). This measure reduces the pore volume of the loose solids/material mixture present in the reaction vessel 1 to about 20%. The compaction step in the working example shown has been conducted in two stages. In the first compaction stage, the reaction vessel 1 filled with the loose solids/material mixture 5 was compressed to a sinusoidal oscillation of 50 Hz with an agitation force of about 375 N/kg for 10 minutes. The compression in the second compression stage was effected at a higher frequency and with a higher agitation force (125 Hz: 575 N/kg). In addition, in the second compression stage, an axial force was exerted on the loose solids/material mixture 5 present in the reaction vessel 1, at a lower pressure of about 18 N/kg. The second stage of the compaction step was conducted for a period of 20 minutes.

[0040] Subsequently, the reaction vessel 1 is connected to a reaction vessel holder of a centrifuge (step 5). The centrifuge is operated in order that an inertia force of about 85 G acts with respect to the reaction vessel 1 or its contents, as indicated by the block arrow. On attainment of the desired inertia force, the exothermic redox reaction intended for melting of the metal is triggered (step 6). In the working example described, this is effected by means of a laser beam introduced from the direction of the axis of rotation of the centrifuge into the reaction vessel which is open counter to the direction of action of the inertia force. Owing to the temperatures that arise here, the metals are melted from the precursor material. The burnoff that begins at the surface of the loose solids/material mixture 5 on the introduction opening side continues in the direction of action of the inertia force, as indicated in this process step in the FIGURE. As a result of the inertia force, the molten metal, following the migrating heat front, will flow into the lower section 2 of the reaction vessel 1. Because of the lower density of the slag formed in this process, this results in effective separation between the metal alloy to be recovered and the slag formed in this process. Once the burnoff and separation process is complete (step 7), the centrifuge is stopped, and the reaction vessel 1 is removed and cooled. Subsequently, the reaction products layered in the reaction vessel 1casting 6 and slag 7are removed and separated from one another. The casting 6 is a high-purity Alloy 600 casting, which is of cylindrical shape in the working example described (step 8).

[0041] In association with the exothermic reaction, the following reactions proceed in the production of this Alloy 600 alloy:

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[0042] For the production of one kilogram of the alloy obtained (Alloy 600) by the above-described process steps, 0.4 KW/kg of energy was used. The metal recovery process runs in a CO.sub.2-neutral manner, such that the CO.sub.2 footprint in this process is 0 kg per kilogram of alloy recovered. Considering the overall value creation chain including the processing of the ore, with use of an embodiment of the process, 19.8 kW/kg of energy is required. The CO.sub.2 footprint is 4.2 kg per kilogram of alloy recovered. For comparison, energy consumption in a conventional industrial recovery of this alloy is 124 kW/kg: the CO.sub.2 footprint is measured as 13.4 kg per kilogram of alloy recovered. This illustrates the advantages of the process described over the conventional industrial metallurgical recovery route. Moreover, the time required for performance of the process is significantly reduced compared to the conventional industrial recovery route.

[0043] The present disclosure makes it clear that refractory metals including metal alloys can be obtained directly as semifinished product or workpiece from the ore by this process. This recovery route is also usable in particular for the recovery of highly alloyed metals that can be recovered in a single process step by this process by comparison with conventional processes. In this process, the alloy is established via the precursor materials used and/or via admixtures, for example scrap made of the desired alloy constituent. Moreover, the exceptional homogeneity of the molten metal should be emphasized, specifically when it is an alloy.

[0044] The invention has been described above by working examples. Without leaving the scope of the current claims, numerous further implementation options will be apparent to a person skilled in the art without any need for specific detailed elucidation thereof.

[0045] While subject matter of the present disclosure has been illustrated and described in detail in the drawings and foregoing description, such illustration and description are to be considered illustrative or exemplary and not restrictive. Any statement made herein characterizing the invention is also to be considered illustrative or exemplary and not restrictive as the invention is defined by the claims. It will be understood that changes and modifications may be made, by those of ordinary skill in the art, within the scope of the following claims, which may include any combination of features from different embodiments described above.

[0046] The terms used in the claims should be construed to have the broadest reasonable interpretation consistent with the foregoing description. For example, the use of the article a or the in introducing an element should not be interpreted as being exclusive of a plurality of elements. Likewise, the recitation of or should be interpreted as being inclusive, such that the recitation of A or B is not exclusive of A and B, unless it is clear from the context or the foregoing description that only one of A and B is intended. Further, the recitation of at least one of A, B and C should be interpreted as one or more of a group of elements consisting of A, B and C, and should not be interpreted as requiring at least one of each of the listed elements A, B and C, regardless of whether A, B and C are related as categories or otherwise. Moreover, the recitation of A, B and/or C or at least one of A, B or C should be interpreted as including any singular entity from the listed elements, e.g., A, any subset from the listed elements, e.g., A and B, or the entire list of elements A, B and C.

LIST OF REFERENCE NUMERALS

[0047] 1 reaction vessel [0048] 2 section [0049] 3 introduction opening [0050] 4 section [0051] 5 loose solids/material mixture [0052] 6 casting [0053] 7 slag