Method for obtaining a refractory metal

Abstract

The invention describes a method for obtaining a refractory metal, which is obtained by means of the following steps: - providing a comminuted starting material of or with the metal to be obtained in oxidically bound form, - providing a reactant, which reacts exothermally after ignition, as bulk goods, which reactant consists of or contains a slag-former having a higher O2 affinity than the metal to be obtained, - providing a bulk goods-material mixture (5) of the starting material and the reactant, - filling a heat-resistant reaction vessel (1) with a batch of the bulk goods-material mixture (5) while leaving a pore volume, - applying an inertial force that acts on the reaction vessel (1) and its contents, - triggering an exothermal reaction of the bulk goods-material mixture (5) while the inertial force is acting thereon through the local supply of thermal energy to the bulk goods-material mixture (5), starting from the edge of the bulk goods-material mixture (5), thus melting the metal to be obtained and separating the molten metal from the slag (7) as a result of the inertial force acting while the redox reaction is in progress, - stopping the inertial force acting on the reaction vessel (1) and its contents at the end of the redox reaction and - after the contents of the reaction vessel have cooled, removing the reaction products (6, 7) from the reaction vessel (1) and separating the obtained metal from the slag (7).

Description

[0001] Process for obtaining a refractory metal

[0002] The invention relates to a process for the extraction of a high-melting metal, in which the metal to be extracted is extracted from a starting material by a redox reaction which is exothermic with regard to its energy balance.

[0003] The extraction of refractory metals or metal alloys is relatively complex. It requires numerous ore processing processes as well as repeated melting and remelting of the prepared starting material. Typical alloys of this type are those using the elements Ti, V, Ni, Ta, Cr, Mo, Nb, and W. In nature, these transition metals occur as oxides and hydroxides and other ceramic compounds. These compounds sometimes contain accompanying elements such as Pb, Fe, Ca, Si, or Mg.

[0004] A process is known from US 7 527 669 B2 in which the metal to be extracted is melted together with a reactive metal and placed in a reaction vessel. Li, Ca or Mg can be used as reactants. The reactant is used so that, when ignited, a sufficiently high heat energy is generated so that the metal to be extracted can be melted from the starting material. To trigger this exothermic process, the reactant is ignited in a suitable manner. The reaction products that remain in the reaction vessel as a result of this reaction are metal or a molten metal alloy molten from the starting material and slag. The molten metal or the molten metal alloy forms a sponge-like structure in the reaction vessel, interspersed with slag particles. To separate the slag from the metal or metal to be extracted.The reaction vessel is then placed in a furnace after the metal alloy to be extracted has been melted, not only to melt any remaining precursor material residues, but above all to melt the remaining slag. According to this state of the art, lithium is the preferred reactant because lithium oxides melt at around 1,500°C, while magnesium oxides, for example, require temperatures of around 3,000°C to melt. This melting destroys the sponge structure of the metal or metal alloy molten in the first extraction step, and due to the different densities, the metal or metal alloy to be extracted segregates, allowing the two reaction products to be separated from one another. As far as is known, this process has not yet found its way into industrial applications. Furthermore, the repeated heat treatment is considered disadvantageous.

[0005] CN 105132724 B proposes using an aluminothermic process to obtain a TiAl-based alloy. This process is essentially similar to the process previously described in US Pat. No. 7,527,669 B2. However, this prior art process does not require the second heating step in a furnace. This prior art uses TiO2 as the starting material, Al powder, a reactant, anhydrous ethanol for the mixing process, and a slag former. To separate the reaction products from one another, the reaction vessel is subjected to an inertial force of at least 500 G, preferably even more than 800 G. The material mixture introduced into the reaction vessel is prepared by mixing the Ti starting material with the Al powder and anhydrous ethanol and grinding it in a ball mill to a particle size of 0.5 to 3 pm.This powder is then mixed with a reactant and a slag former and pressed into a tablet with a compression force of 5 to 20 MPa. This tablet, placed in a reaction vessel, is coated on top with an igniter before the reaction vessel is placed in a high-speed centrifuge. When the desired inertial force (800 to 1200 G) is reached, the igniter ignites and triggers the exothermic redox reaction. As a result of the inertial force, the molten metal alloy is separated from the slag, which is lighter in terms of density. The process described in this document is not suitable for industrial use due to the extremely high inertial force required to separate the molten alloy from the slag.In addition, the process time is quite long due to the grinding, the subsequent drying step, and the time required to maintain the melting temperature. Furthermore, given the reactivity of Al, the grinding process is not without risks if Al has to be ground to the desired particle size.

[0006] A metallothermic process for producing a high-entropy alloy is known from SANIN, VN [et al.]: Centrifugal metallothermic SHS of cast Co-Cr-Fe- Ni-Mn-(X) alloys, In: Russian journal of non-ferrous metals, Vol. 61 , 2020, No. 4, pp. 436-445. - ISSN 1067-8212. To produce this alloy, a self-propagating high-temperature synthesis process with inertial force acting on the reaction vessel or its contents is used. A special feature of these alloys is that the main alloying elements are contained in the alloy in almost equal alloying proportions. The starting product of this previously known process is a mixture of Ni, Cr, Fe, Co and Mn oxides, to which Ti, Si, B, C are added.The exothermic reaction is carried out at an inertial force between 20 and 70 G, with an inertial force of 65 ± 5 G being preferred to achieve the desired high-entropy alloy and the desired microstructure and properties.

[0007] The aim of this experimental study was to determine whether the well-known aluminothermic process is also suitable for producing complex alloys (high-entropy alloys). Numerous factors influence the microstructure of the resulting melt. Since this study specifically focused on a high-entropy alloy, these results cannot be readily transferred to the production of other alloys. Furthermore, this study does not allow for any conclusions as to whether this process can be carried out on an industrial scale, i.e., whether the described process is scalable.

[0008] Based on the prior art discussed above, the object of the invention is to propose a process which is simplified compared to the conventional industrial extraction route for high-melting metals or metal alloys and is particularly suitable for industrial melt-metallurgical extraction of metals, which also avoids the disadvantages identified in the prior art discussed above or at least significantly reduces them.

[0009] This object is achieved according to the invention by a method having the features of claim 1 or alternatively by a method having the features of claim 2.

[0010] Advantageous embodiments emerge from the subclaims and the description.

[0011] The term "metal" used in this document includes transition metals as well as metal alloys. The following statements therefore apply equally to the direct extraction of metals, transition metals, and metal alloys.

[0012] The term "high-melting" used in this statement refers to a metal or metal alloy and refers to substances that have a melting point of at least 900°C.

[0013] In the process according to the invention, the precursors for forming the bulk material mixture to be introduced into a reaction vessel are prepared independently of one another. The material from which the metal is to be obtained is comminuted if it does not naturally have the intended grain or particle size. The target grain size of the precursor material is between 10 and 500 pm. This material is preferably comminuted so that it has a very narrow distribution spectrum with regard to its grain size distribution. Of interest for the process according to the invention is that the grain size of the precursor material can be one or even more than two orders of magnitude larger than the specifications from CN 105132724 B. The comminution effort required is correspondingly lower. The same applies to the provision of the reactant.The typically intended target grain size of the reactant is in the range between 50 pm and 500 pm and can therefore be processed safely with the usual safety precautions. The treatment steps required with regard to the desired target grain size of the starting material and the reactant are carried out independently of one another, so that each comminution step can be adapted to the material to be comminuted. This also applies to the machines used for comminution. Comminution independent of the starting material is particularly advantageous for providing the reactant in the desired grain size, since the reactant sometimes has to be comminuted with greater care. Furthermore, the treatment steps intended for comminution are generally carried out dry, so that drying of either of these precursors is not necessary.

[0014] A material mixture is introduced into a reaction vessel as bulk material. Due to this property, the reaction vessel is filled to its cross-section, regardless of its cross-sectional geometry and cross-sectional size. This allows the cavity provided by the reaction vessel to be filled to its best possible cross-section, and the cavity can be optimally used for introducing the material mixture. According to the first proposed solution, the introduction of the bulk material mixture into the reaction vessel is followed by a step of compacting the bulk material mixture filled into the reaction vessel in order to reduce the pore volume. Typically, the powdery material mixture filled into the reaction vessel will still have a pore volume that is too large for the intended purpose. This type of compaction is achieved by introducing mechanical vibrations into the reaction vessel or acting on its contents.This process can be performed, for example, on a vibrating plate. For larger reaction vessels, other vibrating agitators can also be used.

[0015] The above-described process of compacting the bulk material mixture introduced into the reaction vessel allows for significantly better control of the exothermic reaction. For this reason, the claimed method is scalable, meaning it can also be readily used on an industrial scale. In a preferred embodiment, the bulk material mixture introduced into the reaction vessel is compacted in two stages to reduce its pore volume. A first compaction step is carried out at a lower frequency and a lower vibration force than the second compaction step. Depending on the bulk material mixture in the reaction vessel, the first compaction step is carried out, for example, at a frequency of 40 to 65 Hz and a vibration force of 300 to 500 N / kg based on the total weight.The second compaction step can be carried out at a frequency of 80 to 180 Hz and a vibration force of 450 to 800 N / kg in relation to the total weight. During these compaction steps, sinusoidal vibrations are typically introduced into the bulk material mixture or the reaction vessel in which the bulk material mixture is contained. In such a two-stage compaction of the bulk material mixture, the second compaction step will be designed to last longer than the first compaction step, so that it is, for example, 1.5 to 2.5 times longer than the first compaction step. For example, a time period of 8 to 12, in particular about 10 minutes, can be assumed for the first compaction step, and a time period of 17 to 25, in particular about 20 minutes, for the second compaction step.

[0016] Although compaction of the material mixture introduced into the reaction vessel by applying higher pressing forces is not excluded in this process, it is not beneficial, especially since with such compaction it cannot be guaranteed that the material mixture will develop a uniform pore volume across the filling level in the reaction vessel. In order to have better control of the surface material of the material mixture in the reaction vessel during vibration treatment and to also bring about a certain degree of compaction in this area, such compaction can be combined with a pressing process carried out with low force, for example by means of a punch acting on the surface with low preload, which follows the decreasing filling level in the reaction vessel as a result of such a compaction process or by which a uniaxial force acts on the bulk material mixture during the compaction process.This is, for example, between 5 N / kg and 40 N / kg, whereby the weight refers to the weight of the bulk material mixture used in the reaction vessel. This applied force, which acts uniaxially on the bulk material mixture in the reaction vessel, also depends on the geometry of the reaction vessel, in particular its diameter. In order to achieve the same degree of compaction in a reaction vessel with a larger diameter as in a reaction vessel with a smaller diameter, a correspondingly higher force is required. In a process design with two-stage compaction, such a force acting uniaxially on the bulk material mixture is preferably only applied during the second compaction step. The remaining porosity of the material mixture in the reaction vessel should not be less than 20%.The combustion rate can also be controlled by the porosity of the bulk material mixture. A pore volume of more than 45% to 50% is considered impractical. The pore volume within the bulk material mixture is used as a pathway so that, after the exothermic reaction is triggered to melt the metal to be extracted, the molten metal can flow to the bottom of the reaction vessel as a result of the inertial force acting on it.

[0017] In the next step, the reaction vessel and its contents are subjected to an inertial force. This is typically achieved by placing the reaction vessel in a centrifuge. This process requires significantly lower inertial forces, far below the magnitude specified in CN 105132724 B for obtaining a TiAl alloy. These are generally well below 350 G. In many cases, an inertial force of 80 to 170 G is entirely sufficient to achieve the desired material separation within the reaction vessel. Since there is a remaining pore volume in the material mixture for the separation of the molten metal from the slag, and the pore size is correspondingly large due to the grain size of the particles in the material mixture, even relatively low inertial forces are sufficient to effectively separate the molten metal from the slag.The exothermic reaction process is triggered by a local application of heat to the bulk material mixture. For this purpose, a heat-resistant ignition wire, such as a tungsten wire, can be used, for example, on or adjacent to the material mixture in the reaction vessel. The exothermic reaction in the bulk material mixture can also be triggered by a laser beam impinging on the surface of the material mixture in the reaction vessel. In many cases, the exothermic redox reaction of the bulk material mixture is triggered on the side facing away from the inertial force. The heat front formed by the triggering process then follows the direction of the inertial force. It is also entirely possible for the exothermic reaction to be triggered at multiple points in the bulk material mixture; in such a case, the triggering can occur simultaneously or at different times.How the exothermic reaction of the bulk material mixture is triggered, and whether, if triggering is intended at multiple points, this reaction is triggered at one or more points simultaneously or at different times, depends on the desired course of this redox reaction. This depends on the grain size of the reactant, the pore volume, the cavity geometry of the reaction vessel, and its size. The porosity of the molten metal can also be influenced by the course of the redox reaction and the migration of the heat front through the material mixture in the reaction vessel. The exothermic reaction of the bulk material mixture is triggered while the applied inertial force acts on it.

[0018] According to the second proposed solution, the bulk material mixture is heated by the exothermic reaction to such an extent that both the metal to be extracted and, at least partially, the slag are melted. Separation of the metal to be extracted from the slag then occurs in the liquid state, at least to the extent that the slag is molten. The separation of the two components—metal to be extracted and slag—is then particularly good, with the result that the extracted metal is generally completely free of inclusions. This measure cleverly exploits the greater density contrast between these two components when each is in the liquid state. The density of a substance in the liquid phase is usually lower than in the solid phase.Consequently, the density contrast between the molten metal and the slag, when the latter is also at least partially, preferably largely or even completely in the liquid state, is greater than when the latter is not molten and is in the solid state. By increasing the density contrast between the heavier metal to be extracted and the lighter slag to be separated from it, the separation process can be carried out with a lower inertial force acting on the reaction vessel to achieve the desired result. This is a further step, initially independent of the step of compacting the bulk material mixture filled into the reactant vessel, for implementing this process in a scalable manner. Preferably, both the first proposed solution and the second proposed solution are combined with one another to carry out the method.

[0019] Thus, the degree of liquefaction of the slag can also influence the quality of the molten metal. Even though melting the slag as a whole is particularly advantageous, virtually equally good results can be achieved if only 70% to 80% of the slag is melted. In this context, it should be noted that even small amounts of liquefied slag have a positive effect on the quality of the separation process. According to one embodiment, the melting reaction is carried out such that 25% to 30% of the slag is melted by the heat input.

[0020] The inertial force acting on it during the exothermic reaction ensures particularly good separation of the molten metal from the slag, even when the slag is not molten, but better when both phases are in their liquid state, whereby a layer forms in the reaction vessel, with the extracted metal in the section adjacent to the bottom of the reaction vessel and the slag above it. The molten metal is collected in a collecting volume. This can be the section adjacent to the bottom of the reaction vessel. It is also possible for the collecting volume to be provided by a collecting vessel connected to the reaction vessel. The collecting volume can also be used as a mold in which the molten metal solidifies.This process allows a semi-finished product or a cast body, particularly one with a complex geometry, to be produced from the starting material in a single melting step. Such a semi-finished product or cast body can have a variety of shapes. Even undercuts can be produced this way if the section of the collecting volume containing the extracted metal can be opened to remove the hardened metal. It is also possible to use collecting volumes that are destroyed to remove the hardened metal (of the semi-finished product or the cast body). In such a case, this can be a clay mold, which is then replaced with a new one for the next melting process.If such a master mold is part of the reaction vessel as a collecting volume, its cross-sectional area will be designed to be smaller than that of the section above it, towards the opening of the reaction vessel, to ensure that it is completely filled with the molten metal. The slag is then located in the area of ​​the reaction vessel adjacent to the casting mold. When designing such a reaction vessel with a master mold, be it for the production of a semi-finished product or a casting with a complex geometry, the filling of the reaction vessel can be arranged in such a way that the collecting volume is not filled with the bulk material mixture, but only the section above it, towards the filling opening. For example, a sieve made of heat-resistant wire can be used to leave the master mold free when filling the reaction vessel.According to another embodiment, a metal foil is also provided to separate the antechamber of the reaction vessel, into which the bulk material mixture is poured, from the adjoining master mold. This metal foil is preferably made of a metal that is also contained in the metal to be extracted. If, for example, a Ni alloy is extracted using this process, it is expedient to use a Ni foil. If the alloy to be extracted contains Al, for example, an Al foil can be used to separate the antechamber from the master mold. These foils are also melted when the metal is melted and then become part of the alloy. The advantage here is that no slag is produced in the master mold during the ongoing process, which would then have to be separated from it due to the applied inertial force. This shortens the process time.Such semi-finished products can be, for example, bars or hollow bars.

[0021] Connected to or part of such a reaction vessel, several master molds could also serve as collecting volumes into which the molten metal flows due to the inertial force acting on it. Especially when smaller semi-finished products or workpieces are required, several of these can be provided in a single melting process.

[0022] In the process described above, several different crushed starting materials can also be provided if the metal to be extracted is an alloy rather than an elemental metal. The addition of recycled material (recycled scrap) to the starting material is also possible. This can certainly be alloy-forming material. In another process embodiment, the reactant contains one or more alloying elements, which are present either in elemental or bound form and with which the metal to be extracted from the starting material forms a bond. This is particularly advantageous for refractory metals. In this way, Ti, Ni, Cr, and other refractory alloys can be produced with virtually any alloying elements in a single melting process, fueled by the prescribed exothermic reaction.

[0023] The bulk material mixture introduced into the reaction vessel can be graded within the reaction vessel. Such grading typically occurs in the direction of the inertial force acting upon the metal during melting. This can, for example, be due to a different mixing ratio of individual components contained in the bulk material mixture, or to certain raw materials or additives not being distributed homogeneously throughout the height of the reaction vessel. Since this process involves metal extraction via a direct route, it can also be used to easily produce a graded material.

[0024] Depending on the size of the reaction vessel, particularly its height or its extension in the direction of the inertial force acting on it, as well as the volume of the bulk material mixture, the exothermic reaction process takes place in a relatively short time. Depending on the aforementioned conditions, such a process can take place in as little as a few tens of seconds. Even with larger volumes of the bulk material mixture, a reaction time of only a few minutes is required. The melting of the metal(s) and their crystallization (hardening) must be included in this calculation.What must be taken into account when considering the burn-off time and the movement of the heat front through the bulk material mixture is that the inertial force acting on the reaction vessel and its contents during the reaction process completes the desired separation of molten metal and slag across the entire extent of the reaction vessel in the direction of the inertial force acting on it. This flow path of the molten metal simultaneously leads to a homogenization of the melt, which is particularly important when a metal alloy is to be melted from different starting materials. One embodiment of the process provides for the reaction vessel to be equipped with thermal insulation so that the heat generated by the exothermic reaction remains in the reaction vessel longer than the actual reaction, at a temperature level at which the metal to be extracted has not yet hardened.Thus, this process can increase the recovery rate from the raw material used.

[0025] The reaction vessel is typically inert with respect to the elements or compounds present in the bulk material mixture. Typically, it is not desirable for elements to be dissolved from the reaction vessel during the exothermic reaction process and introduced into the melt.

[0026] The relatively low inertial force used in this process, compared to previously known processes, makes it scalable, particularly in that the amount of metal to be extracted with each batch can be sufficiently large for economic exploitation. With the forces described above, samples weighing several tens of kilograms or even several hundred kilograms can be produced in a reaction vessel. Reaction vessels capable of producing semi-finished products or even castings with a higher weight can also be used.

[0027] A unique feature of this process is that the metal extraction process can be influenced by two key control variables: the temperature triggered by the exothermic reaction and the inertial force. The temperature of the molten metal can be used to influence its viscosity. Generally, lower viscosity molten metal requires less inertial force for the separation process. The temperature and inertial force for the metal melting and separation process are determined depending on the metal to be extracted and also on the design of the part of the reaction vessel into which the molten metal is to flow.

[0028] To melt metals from the oxides used as raw materials, different temperatures are required depending on the metal. The exothermic process used to melt metals or metal alloys can be influenced by physical parameters such as the particle size of the crushed raw material, the inertial force acting on the bulk material mixture, the degree of compaction or the established pore volume, and the design of the reaction vessel. The smaller the particle size, the shorter the time can be to obtain the metal to be melted. The inertial force can influence the speed at which the heat front moves through the bulk material mixture within the reaction vessel, as well as the reaction temperature. At higher inertial forces, the heat front moves more quickly through the bulk material mixture.Higher inertial forces, when provided by centrifuges, as is often the case, influence the reaction temperature, since the cooling effect caused by them is greater at higher speeds.

[0029] The degree of compaction can influence the intensity and duration of the exothermic reaction at the individual particles, as well as the transport speed at which the molten metal flows into the collecting volume. The size and design of the collecting volume intended to collect the liquid melt influences the cooling rate or cooling curve of the molten metal collected therein. It is certainly possible to preheat the collecting volume and the bulk material mixture introduced therein, for example to a temperature between 500°C and 600°C, before the exothermic reaction is started. The molten metal components initially collected therein then cool correspondingly more slowly on the preheated inner wall of the vessel used as the collecting volume, with the result that the crystal structure of the collected metal is more uniform overall.

[0030] The metal extraction process can also be influenced by the composition of the reactant or by additives and thus chemically. For example, these can contain oxides that increase or decrease the reaction temperature. Other reactant components can be used to delay the exothermic reaction. For example, additives can be used to increase or decrease the melting temperature of the slag. Materials used for such purposes, usually oxides, are typically inert with regard to the metal to be extracted. CaO can be used to lower the slag melting temperature, while MgO can increase it. CaO is used when a metal with a relatively low melting temperature is to be extracted. If the melting point of the slag is lower than the melting temperature of the metal to be extracted, MgO can be used to increase the slag melting temperature.

[0031] The particle size of the starting material and the reactant also influence the energy control of the melting reaction in the reaction vessel. The smaller the grain size, the faster the reaction proceeds per particle. Therefore, the reaction of particularly exothermic mixtures can be slowed by using a larger particle size. A larger particle size has a positive effect on the upstream comminution process, as it can be carried out more quickly. Thus, the particle size is also cleverly used for energy control.

[0032] The factors described above ensure the scalability of the process, so that it can also be carried out with larger batches, for example 10 to 200 kg, in a controlled manner and, above all, with consistent results.

[0033] The above statements clearly demonstrate that this process differs from currently industrially used extraction methods not only in its significantly lower number of process steps, but above all in the resulting significantly improved energy efficiency. Furthermore, the potential of the ore used as a precursor can be better utilized. Furthermore, emissions, especially CO2 emissions, are significantly reduced. Regarding energy consumption, for example, in the production of Ni extraction, energy consumption was reduced to approximately 20% and CO2 emissions to approximately 30%. The same applies to all other alloys.

[0034] The invention is explained below using an exemplary embodiment with reference to the flow chart in Figure 1. The following describes the application of the inventive method for the direct extraction of an Alloy 600 alloy (EN 2.4816). The inventive method produces a NiCrFe alloy with the following composition: Cr 15 wt.%, Fe 8 wt.%, the remainder Ni plus unavoidable impurities totaling less than 1%. This alloy is also known as Alloy 600 (EN 2.4816).

[0035] NiOC^Ch and Fe2O5 are primarily used as starting materials. In this exemplary embodiment, these are ground together to a grain size of approximately 85 pm (step 1). Al is used as the reactant in this exemplary embodiment. Likewise, Mg, Si, or mixtures thereof, typically together with a conventional flux, can also be used as the reactant. The corresponding precursor is ground to a grain size of 70 pm (also step 1). In a subsequent step - process step 2 - the precursor and the reactant are mixed together. An industrial mixing machine is used for this. The mixing process is carried out so that as little energy as possible is introduced into the mix during mixing. Both the comminution process and the mixing process are carried out dry.

[0036] The bulk material mixture removed from the mixer is then poured into a reaction vessel 1 (step 3). The design of the reaction vessel 1 shown in the figure is merely an example of a reaction vessel. The reaction vessel 1 comprises a lower section 2, which is designed as a master mold. At the end of the extraction process, this part of the section contains the alloy hardened as a cast ingot. The lower section 2 merges into an upper section 4 towards the filling opening 3 of the reaction vessel 1. This upper section 4 has a larger diameter than the section 2 used as the master mold. After the reaction vessel 1 has been filled, the bulk material mixture contained therein is compacted on a vibrating plate (step 4). This measure reduces the pore volume of the bulk material mixture contained in the reaction vessel 1 to approximately 20%.In the illustrated embodiment, the compaction step was carried out in two stages. In the first compaction stage, the reaction vessel 1 filled with the bulk material mixture 5 was subjected to a sinusoidal vibration of 50 Hz with a vibration force of approximately 375 N / kg for 10 minutes. Compaction in the second compaction stage took place at a higher frequency and with a higher vibration force (125 Hz; 575 N / kg). In addition, in the second compaction stage, an axial force was exerted on the bulk material mixture 5 contained in the reaction vessel 1, specifically with a low pressure of approximately 18 N / kg. The second stage of the compaction step was carried out for a period of 20 minutes.

[0037] Subsequently, the reaction vessel 1 is connected to a reaction vessel holder of a centrifuge (step 5). The centrifuge is operated so that an inertial force of approximately 85 G acts on the reaction vessel 1 or its contents, as indicated by the block arrow. When the desired inertial force is reached, the exothermic redox reaction intended to melt the metal is triggered (step 6). In the illustrated embodiment, this is achieved by a laser beam introduced from the direction of the centrifuge's axis of rotation into the reaction vessel, which is open against the direction of the inertial force. As a result of the temperatures generated during this process, the metals are melted from the starting material. The combustion that begins on the surface of the bulk material mixture 5 on the filling opening side continues in the direction of the acting inertial force, as indicated in this process step in the figure.Due to the force of inertia, the molten metal will flow into the lower section 2 of the reaction vessel 1, following the moving heat front. Due to the lower density of the slag produced during this process, this effectively separates the metal alloy to be extracted from the slag produced during this process. Once the burn-off and separation process is complete (step 7), the centrifuge is stopped, the reaction vessel 1 is removed, and allowed to cool. The reaction products layered in the reaction vessel 1—casting 6 and slag 7—can then be removed and separated. The casting 6 is a high-purity Alloy 600 casting, which in the illustrated embodiment has a cylindrical shape (step 8).

[0038] In connection with the exothermic reaction, the following reactions take place during the production of this Alloy 600 alloy: 1. 3 NiO + 2 AI 3 Ni" q<h2 style=";text-align:left;direction:ltr">+ AI2O3 + AH<h2 style=";text-align:left;direction:ltr"> <h2 style=";text-align:left;direction:ltr">

[0039] <h2 style=";text-align:left;direction:ltr"> 2. Cr2O3+ Al Cr<h2 style=";text-align:left;direction:ltr"> liq <h2 style=";text-align:left;direction:ltr"> - + AI2O3 + AH<h2 style=";text-align:left;direction:ltr"> <h2 style=";text-align:left;direction:ltr">

[0040] <h2 style=";text-align:left;direction:ltr"> 3. Fe2Q3 + Al — > Fe<h2 style=";text-align:left;direction:ltr"> liq <h2 style=";text-align:left;direction:ltr"> + AI2O3 + AH_<h2 style=";text-align:left;direction:ltr"> <h2 style=";text-align:left;direction:ltr">

[0041] <h2 style=";text-align:left;direction:ltr"> NiO + Cr2O3+ Fe2O3+ (8 / 3) • Al (NiCrFe)<h2 style=";text-align:left;direction:ltr"> liq <h2 style=";text-align:left;direction:ltr"> + (7 / 3) • Ai2O3+ LAH<h2 style=";text-align:left;direction:ltr"> <h2 style=";text-align:left;direction:ltr">

[0042] To produce one kilogram of the alloy obtained (Alloy 600) using the process steps described above, an energy consumption of 0.4 kW / kg was used. The metal extraction process is CO2-neutral, so that the CO2 footprint for this process is 0 kg per kilogram of alloy extracted. When considering the entire value chain, including ore processing, 19.8 kW / kg of energy is required when using the process according to the invention. The CO2 footprint amounts to 4.2 kg per kilogram of alloy extracted. By comparison, the energy consumption for conventional industrial extraction of this alloy is 124 kW / kg; the CO2 footprint is 13.4 kg per kilogram of alloy extracted. This highlights the advantages of the described process over the conventional industrial smelting metallurgy route.In addition, the time required to carry out the process is significantly reduced compared to the conventional industrial extraction route.

[0043] The description of the invention makes it clear that this process can be used to extract refractory metals, including metal alloys, directly from the ore as semi-finished products or workpieces. This extraction route is particularly suitable for the extraction of high-alloy metals, which can be extracted in a single process step using this process, unlike conventional methods. In this process, the alloy is adjusted via the input materials and / or additives, such as scrap from the desired alloy component. Furthermore, the particular homogeneity of the molten metal, especially when it is an alloy, is noteworthy. The invention has been described above using exemplary embodiments.Without departing from the scope of the applicable claims, numerous further implementation possibilities arise for a specialist without the need to explain these in detail.

[0044] List of reference symbols Reaction vessel Section Filling opening Section Bulk material mixture Casting body Slag

Claims

Patent claims Process for the extraction of a high-melting metal, in which the metal to be extracted is extracted from a starting material by a redox reaction which is exothermic in terms of its energy balance and comprises the following steps: Providing a crushed primary material made of or containing the metal to be extracted in oxidically bound form, providing a reactant which reacts exothermically after ignition as bulk material, which reactant consists of or contains a slag former having a higher O2-A f in ity than the metal to be extracted, providing a bulk material mixture (5) made of the primary material and the reactant, Filling a heat-resistant reaction vessel (1) with a batch of the bulk material mixture (5) while leaving a pore volume, Reducing the pore volume of the bulk material mixture (5) introduced into the reaction vessel (1) by compacting the bulk material mixture (5) by introducing mechanical vibrations, Applying an inertial force acting on the reaction vessel (1) with its contents, Triggering an exothermic reaction of the bulk material mixture (5) during the inertial force acting on it by locally supplying thermal energy to the bulk material mixture (5), starting from the edge of the bulk material mixture (5), thereby melting the metal to be extracted and separating the molten metal from the slag (7) as a result of the inertial force acting during the redox reaction, Terminating the inertial force acting on the reaction vessel (1) and its contents after completion of the redox reaction and after cooling of the reaction vessel contents. Removing the reaction products (6, 7) from the reaction vessel (1) and separating the metal obtained from the slag (7).

2. A process for the extraction of a high-melting metal, in which the metal to be extracted is extracted from a starting material by a redox reaction which is exothermic in terms of its energy balance and comprises the following steps: Providing a crushed primary material made of or containing the metal to be extracted in oxidically bound form, providing a reactant which reacts exothermically after ignition as bulk material, which reactant consists of or contains a slag former having a higher O2-A f in ity than the metal to be extracted, providing a bulk material mixture (5) made of the primary material and the reactant, Filling a heat-resistant reaction vessel (1) with a batch of the bulk material mixture (5) while leaving a pore volume, Applying an inertial force acting on the reaction vessel (1) with its contents, Triggering an exothermic reaction of the bulk material mixture (5) during the inertial force acting on it by locally supplying thermal energy to the bulk material mixture (5), starting from the edge of the bulk material mixture (5), thereby melting the metal to be extracted and separating the molten metal from the slag (7) which is at least partially melted as a result of the heat input as a result of the inertial force acting during the redox reaction, Terminating the inertial force acting on the reaction vessel (1) and its contents after completion of the redox reaction and after cooling of the reaction vessel contents. Removing the reaction products (6, 7) from the reaction vessel (1) and separating the metal obtained from the slag (7).

3. Method according to claim 2, characterized in that after filling the reaction vessel with a batch of the bulk material mixture (5), the pore volume of the material introduced into the reaction vessel (1) introduced bulk material mixture (5) is reduced by compacting it by introducing mechanical vibrations.

4. Process according to one of claims 1 to 3, characterized in that the reactant is comminuted to a grain size of between 10 pm and 500 pm to provide the precursor.

5. Process according to one of claims 1 to 4, characterized in that the reactant has a grain size between 50 pm and 500 pm.

6. Method according to one of claims 1 to 5, characterized in that, in order to provide the bulk material mixture (5), the comminuted primary material and the reactant are mixed in a closed mixing container, preferably without introducing energy into the mixture.

7. Method according to one of claims 1 to 6, characterized in that the reaction vessel (1) with the bulk material mixture (5) is subjected to the following process steps while leaving a pore volume of 10 to 30% in the reaction vessel (1).

8. Method according to one of claims 1 to 7, characterized in that the bulk material mixture (5) is introduced into the reaction vessel (1) in a gradation with regard to its different components.

9. Method according to one of claims 1 to 8, characterized in that the inertial force applied to the reaction vessel (1) is less than 350 G, in particular less than 200 G.

10. The method according to claim 9, characterized in that a centrifuge with a plurality of reaction vessel holders, two of which are arranged diametrically opposite one another with respect to the axis of rotation, is used to apply the inertial force.

11. Method according to one of claims 1 to 10, characterized in that the exothermic reaction is triggered by means of a resistance heating element and / or by means of a laser beam.

12. Method according to one of claims 1 to 11, characterized in that the reaction vessel (1) in its section (2), in which the molten metal collects during the exothermic reaction, simultaneously serves as a primary forming collecting volume for the metal to be extracted, in which the molten metal hardens, forming the cavity of the collecting volume.

13. Method according to one of the preceding claims, characterized in that the reaction vessel (1) is filled in such a way that the collecting volume connected thereto and intended for collecting the molten metal is not filled with the bulk material mixture (5), but only the volume present in the direction of the filling opening, wherein in order to keep the collecting volume free, a bulk material mixture barrier which allows the molten metal to pass through is used to separate the bulk material mixture (5) filled into the reaction vessel (1) from the collecting volume.

14. The method according to claim 13, characterized in that the bulk material mixture barrier is made of a heat-resistant material, such as a ceramic filter or a sieve made of a heat-resistant wire.

15. The method according to claim 13, characterized in that the bulk material mixture barrier for separating the bulk material mixture (5) in the reaction vessel (1) from the collecting volume consists of a metal which is also contained in the metal to be extracted or of which the metal to be extracted consists. Process according to one of claims 1 to 15, characterized in that the reactant is simultaneously the slag former. Process according to one of claims 1 to 15, characterized in that the reactant contains a slag former. Process according to one of claims 1 to 17, characterized in that one or more of the elements Al, Mg and / or Si are used as reactants. Process according to one of claims 1 to 18, characterized in that the exothermic reaction of the bulk material mixture (5) in the reaction vessel (1) is triggered at different locations.

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