Method for extracting high-melting-point metal

Abstract

The invention relates to a method for extracting high-melting-point metals, comprising the following steps:-providing a comminuted raw material consisting of or comprising the metals to be extracted in an oxidatively bound form,-providing a reactant for an exothermic reaction after ignition as a bulk material, the invention relates to a method for extracting metal from raw materials, comprising the steps of:-providing a bulk material-material mixture (5) from said raw materials and reactants,-filling a batch of bulk material-material mixture (5) into a heat-resistant reaction vessel (1) while retaining a pore volume,-removing the bulk material-material mixture (5) from the raw materials and reactants, and-separating the bulk material-material mixture (5) from the raw materials and reactants to obtain the metal extracted from the bulk material-material mixture (5). Applying an inertial force acting on the reaction vessel (1) and the contents thereof, initiating an exothermic reaction of the bulk mass-material mixture (5) during the action of the inertial force on the bulk mass-material mixture (5) by locally supplying thermal energy to the bulk mass-material mixture (5) starting from the edge of the bulk mass-material mixture (5), the metal to be extracted is melted and the molten metal is separated from the slag (7) by the inertia force acting during the redox reaction, after the redox reaction is completed, the inertia force acting on the reaction vessel (1) and the contents thereof is terminated, and after the contents in the reaction vessel are cooled, the molten metal is separated from the slag (7) by the inertia force acting during the redox reaction. The reaction products (6, 7) are removed from the reaction vessel (1) and the extracted metals are separated from the slag (7).

Description

[0001] The subject of the invention is a method for extracting refractory metals, in which the metal to be extracted is extracted from a raw material by a redox reaction which is exothermic in terms of its energy balance.

[0002] The extraction of high-melting-point metals or metal alloys is relatively complex. This requires numerous ore processing steps and multiple melting or remelting of the respectively prepared raw materials. Typical alloys of this type are alloys with the elements Ti, V, Ni, Ta, Cr, Mo, Nb and W. In nature, these transition metals occur in the form of oxides and hydroxides and other ceramic compounds. Sometimes these compounds contain accompanying elements such as Pb, Fe, Ca, Si or Mg.

[0003] A method is known from US 7527669 B2, in which, in order to melt the metal to be extracted, it is introduced into a reaction vessel together with a reactive metal. Li, Ca or Mg can be used as a reactant. The reactant is used so that after it is ignited, sufficiently high heat energy is generated so that the metal to be extracted can be melted from the raw material. In order to initiate this exothermic process, the reactant is ignited in a suitable manner. Through this reaction, the metal or molten metal alloy and slag melted from the raw material remain in the reaction vessel as reaction products. The molten metal or molten metal alloy forms a sponge structure in the reaction vessel, in which slag particles are scattered. In order to separate the slag from the metal to be extracted or the metal alloy to be extracted, the reaction vessel is then introduced into the furnace so that not only the remaining raw material residue is melted, but also in particular so that the remaining slag becomes a melt. According to this prior art, lithium is preferably used as a reactant because lithium oxide melts at about 1500° C., while magnesium oxide, for example, requires a temperature of about 3000° C. for melting. By this melting, the sponge structure of the metal or metal alloy melted in the first extraction step is destroyed and, due to the different densities, the metal to be extracted or the metal alloy to be extracted is separated so that the two reaction products can then be separated from each other. As far as is known, this method has not yet entered industrial application. In addition, multiple temperature treatments are considered disadvantageous.

[0004] CN 105132724 B proposes to use aluminothermic method to extract TiAl-based alloy. In principle, this is similar to the method described in US7527669 B2 before. However, in this previously known method, it is not necessary to carry out the second heating step in the furnace. In this prior art, the raw materials used are TiO2, Al powder and reactants and anhydrous ethanol and slag-forming agents for the mixing process. In order to separate the reaction products from each other, the reaction vessel is subjected to at least 500G, preferably even greater than 800G inertial force. The material mixture introduced into the reaction vessel is prepared by mixing Ti raw materials with Al powder and anhydrous ethanol and grinding to a particle size of 0.5 to 3 μm in a ball mill. Then the powder is mixed with reactants and slag-forming agents and pressed into tablets with a pressure of 5 to 20MPa. The tablets placed in the reaction vessel are coated with ignition agents on the top surface, and then the reaction vessel is placed in a high-speed centrifuge. When the required inertial force (800 to 1200G) is reached, the ignition agent ignites and triggers an exothermic redox reaction. Due to the inertial forces, the molten metal alloy is separated from the slag, which is relatively light in terms of its density. Due to the extremely high inertial forces required to separate the molten alloy from the slag, the method known from this document cannot be used for industrial purposes. In addition, due to the grinding, the subsequent required drying step and the time required to maintain the melting temperature, the process time lasts quite long. In addition, considering the reactivity of Al, if Al has to be ground to the required particle size, the grinding process is not without risks.

[0005] SANIN, VN [et al.]: Centrifugal metallothermic SHS of cast Co-Cr-Fe-Ni-Mn-(X) alloys, Russian journal of non-ferrous metals, Vol. 61, 2020, No. 4, pp. 436-445 - ISSN 1067-8212 discloses a metallothermic method for producing high entropy alloys. To produce such alloys, a self-expansion high temperature synthesis method is used, in which inertial forces act on the reaction vessel and its contents. The peculiarity of these alloys is that the main alloying elements are contained in the alloy in almost equal alloy proportions. The starting product of this previously known method 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 under an inertial force of 20 to 70 G, wherein in order to achieve the desired high entropy alloy, an inertial force of 65±5 G is preferred to achieve the desired structure and desired properties.

[0006] The aim of this experimental investigation was to determine whether the known aluminothermic method is also suitable for the production of complex alloys (high-entropy alloys). Many factors influence the formation of the structure of the resulting melt. Since this study dealt specifically with high-entropy alloys, the results cannot be easily transferred to the production of other alloys. Furthermore, the study does not allow any conclusions to be drawn as to whether the method can also be carried out on an industrial scale, i.e. whether the method described is scalable.

[0007] Based on the prior art discussed above, the object of the present invention is to propose a method which is simplified compared to the conventional industrial extraction routes of high-melting-point metals or metal alloys and is particularly suitable also for the industrial molten metallurgical extraction of metals, which also avoids or at least significantly reduces the disadvantages shown by the prior art discussed above.

[0008] According to the invention, this object is achieved by a method having the features of claim 1 or, alternatively, by a method having the features of claim 2 .

[0009] Advantageous embodiments emerge from the dependent claims and the description.

[0010] The term "metal" as used in these statements also includes transition metals as well as metal alloys. Therefore, the following statements also apply to the direct extraction of metals, transition metals and metal alloys.

[0011] The term "high melting point" used in these statements with respect to metals or metal alloys is to be understood as referring to those materials having a melting temperature of at least 900°C.

[0012] In the method according to the invention, the raw materials for forming the bulk material-material mixture to be introduced into the reaction vessel are prepared independently of each other. If the material from which the metal is to be extracted does not have the expected particle size or particle size itself, it is crushed. The target particle size of the raw material is set to 10 to 500 μm. The material is preferably crushed in such a way that it has a fairly narrow distribution spectrum in terms of its particle size distribution. The interesting thing about the method according to the invention is that the particle size of the raw material can be one or even more than two orders of magnitude larger than the specifications of CN 105132724 B. The crushing cost to be performed is correspondingly low. The same applies to the provision of the reactant. The target particle size of the reactant is usually set to 50 μm to 500 μm, so it can be safely handled by conventional safety precautions. The necessary processing steps for the desired target particle size of the raw material and the reactant are carried out independently of each other so that each crushing step can be adapted to the material to be crushed. This also applies to the machine for crushing. In particular, in order to provide a reactant of the desired particle size, it is advantageous to crush it independently of the raw material, because sometimes the reactant must be crushed more carefully. Furthermore, the process step provided for comminution is carried out essentially dry, so that there is no need to dry one of the raw materials.

[0013] The material mixture is introduced into the reaction vessel as a bulk material. Due to this property, the reaction vessel is filled in a cross-sectional filling manner with respect to its cavity, and more precisely, regardless of its cross-sectional geometry and cross-sectional dimensions. Therefore, the cavity provided by the reaction vessel can be filled as optimally as possible with respect to its cross-section, and the cavity can be optimally used to introduce the material mixture. According to the first proposed solution, the introduction of the bulk material-material mixture into the reaction vessel is followed by a step of compacting the bulk material-material mixture filled into the reaction vessel in order to reduce the pore volume. Typically, the powder material mixture filled into the reaction vessel has a pore volume that is still too large for the intended purpose. This compaction occurs by introducing mechanical vibration into the reaction vessel or acting on its contents. For example, the process can be carried out on an oscillating plate. For larger reaction vessels, other oscillating agitators can also be used.

[0014] Due to the above-mentioned compacting of the bulk material mixture introduced into the reaction vessel, the course of the exothermic reaction can be significantly better controlled. The claimed method is therefore scalable, ie it can also be easily used on an industrial scale.

[0015] In a preferred embodiment, the bulk material-material mixture filled into the reaction vessel is compacted in two stages to reduce its pore volume. Compared with the second compaction step, the first compaction step is carried out at a lower frequency and a lower oscillation force. According to the bulk material-material mixture present in the reaction vessel, the first compaction step is carried out, for example, at a frequency of 40 to 65 Hz and an oscillation 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 an oscillation force of 450 to 800 N / kg based on the total weight. During these compaction steps, sinusoidal vibrations are usually introduced into the bulk material-material mixture or the reaction vessel containing the bulk material-material mixture. In this two-stage compaction of the bulk material-material mixture, the second compaction step will be designed to be longer than the first compaction step in terms of its duration, so that it is, for example, 1.5 to 2.5 times longer than the first compaction step. For example, the first compaction step time period may be set to a time period of 8 to 12 minutes, in particular a time period of about 10 minutes, and the second compaction step time period may be set to a time period of 17 to 25, in particular a time period of about 20 minutes.

[0016] In this method, although it is not excluded to compact the material mixture introduced into the reaction vessel by applying a higher pressure, this is not beneficial, especially when such compaction can not ensure that the material mixture forms a uniform pore volume on the filling height in the reaction vessel. In order to better control the surface material of the material mixture present in the reaction vessel during the oscillation treatment process and also to produce a certain compaction in this area, this compaction can be combined with a pressing process performed with very little force, for example, by acting on a stamping part on the surface with a very small prestress, which follows the filling height reduced in the reaction vessel due to this compaction process, or by acting on the bulk material-material mixture by a uniaxial force during the compaction process. For example, it is 5N / kg to 40N / kg, wherein the weight is based on the weight of the bulk material-material mixture used to fill the reaction vessel. The force applied on the bulk material-material mixture in the reaction vessel by the uniaxial action 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 larger force is required. When designing a method with two-stage compaction, it is preferred to apply such a uniaxial force acting on the bulk material mixture only during the second compaction step. The residual porosity of the material mixture in the reaction vessel should not be less than 20%. The burning rate can also be controlled by the porosity of the bulk material mixture. Pore volumes exceeding 45% to 50% are considered to be useless. The pore volume within the bulk material mixture is used as a channel, whereby after initiating an exothermic reaction to melt the metal to be extracted, the molten metal can flow to the bottom of the reaction vessel due to the inertial forces acting.

[0017] In the next step, the reaction vessel and its contents are subjected to inertial forces. This is usually accomplished by arranging the reaction vessel in a centrifuge. The method requires significantly lower inertial forces, which are much lower than the order of magnitude given in CN 105132724 B for extracting TiAl alloys. It is typically significantly lower than 350G. In many cases, an inertial force of 80 to 170G is fully sufficient to be able to perform the required material separation in the reaction vessel. Due to the presence of residual pore volume in the material mixture in order to separate the molten metal from the slag, and due to the particle size of the particles of the material mixture, the pore size is correspondingly large, so a relatively small inertial force is sufficient to effectively separate the molten metal from the slag.

[0018] The exothermic reaction process is initiated by locally heating the bulk material-material mixture. For example, a heat-resistant ignition wire, such as a tungsten wire, arranged on or near the material mixture in the reaction vessel can be used for this purpose. The exothermic reaction in the bulk material-material mixture can also be initiated by a laser beam shot onto the surface of the material mixture in the reaction vessel. In many cases, the exothermic redox reaction of the bulk material-material mixture is initiated on the side opposite to the inertial force. Then, the heat front formed by the initiation process is transmitted in the direction of the inertial force. The exothermic reaction is also entirely possible to be initiated at multiple points in the bulk material-material mixture, wherein in this case the initiation can be carried out simultaneously or staggered in time. How to initiate the exothermic reaction of the bulk material-material mixture, and if it is set to initiate at multiple points, whether to initiate the reaction at one or more points simultaneously or staggered in time depends on the required process of the redox reaction. This depends on the particle size of the reactants, the pore volume, the cavity geometry of the reaction vessel and its size. The porosity of the molten metal may also be affected by the migration of the redox reaction process and the heat front through the material mixture in the reaction vessel. When the applied inertial forces act on the bulk material mixture, an exothermic reaction of the bulk material mixture is initiated.

[0019] According to the second proposed solution, the bulk material-material mixture is heated to the extent that the metal to be extracted and at least part of the slag are melted by the reaction carried out exothermically. The separation of the metal to be extracted from the slag is then carried out in the liquid state, at least to the extent that the slag has melted. The two components-the metal to be extracted and the slag-are particularly well separated from each other at this time, and more precisely, the result is that the extracted metal is usually completely free of inclusions. The higher density contrast of the two components when they are in the liquid state is cleverly utilized by this measure. The density of the liquid phase material is generally lower than the density of the solid phase. Therefore, when the slag is also at least partially, preferably substantially or even completely in the liquid state, the density contrast between the molten metal and the slag is greater than when it is not melted and in the solid state. By increasing the density contrast between the heavier metal to be extracted and the lighter slag to be separated therefrom, the separation process can be carried out using the lower inertial force acting on the reaction vessel to achieve the desired result. This is a further step of the step of compacting the bulk material-material mixture initially filled into the reactant container so as to carry out the process in a scalable manner. Preferably, the first proposed solution and the second proposed solution are combined with each other to perform the method.

[0020] The quality of the molten metal is therefore also influenced by the degree of liquefaction of the slag. Even if slag melting is particularly advantageous overall, almost equally good results can be achieved if only 70% to 80% of the slag is melted. It should be pointed out in this regard that even small liquefied slag portions have a positive effect on the quality of the separation process. According to one embodiment, the melting reaction is carried out in such a way that 25% to 30% of the slag is melted by the heat input.

[0021] The inertial forces acting thereon during the exothermic reaction process cause a particularly good separation of the molten metal from the slag, even if the slag is not melted, but if both phases are in a liquid state, it is better, thereby forming a layer in the reaction vessel, wherein the extracted metal is located in a local area adjacent to the bottom of the reaction vessel, and the slag is located above it. The molten metal is collected in a collection volume. It can be a local area adjacent to the bottom of the reaction vessel. The collection volume can also be provided by a collection container connected to the reaction vessel. The collection container can also be used as a forming mold, in which the molten metal solidifies. Through this process, semi-finished products or castings, particularly those with complex geometries, can be produced from raw materials in a single melting step. This semi-finished product or this casting can have different shapes. If the local collection space where the extracted metal is located can be opened to take out the hardened metal, then even backcuts can be made in this way. It is also possible to use a collection volume, which is destroyed to take out the hardened metal (semi-finished product or casting). In this case, it can be a clay mold, which is then replaced by a new mold in the next melting process. If a part of the reaction vessel is such a forming mold as a collection volume, in order to ensure that it is completely filled with molten metal, its cross-sectional area will be designed to be smaller than the cross-sectional area of ​​the local part located above it toward the reaction vessel opening. Then the slag is located in the reaction vessel adjacent to the casting mold. When forming such a reaction vessel with a forming mold, whether it is used to produce a semi-finished product or a casting with a complex geometry, the filling of the reaction vessel can be arranged so that the collection volume is not filled with a bulk material-material mixture, but only the local part above it toward the filling port direction. For example, a screen made of heat-resistant wire can be used to release the forming mold when filling the reaction vessel. According to another embodiment, in order to separate the antechamber of the reaction vessel filled with a bulk material-material mixture from the adjacent forming mold, a metal film is also provided. It is preferably composed of a metal also contained in the metal to be extracted. For example, if the method is used to extract a Ni alloy, it is recommended to use a Ni film. For example, if the alloy to be extracted contains Al, an Al film can be used to separate the antechamber from the forming mold. When the metal melts, these films will also melt and then become part of the alloy. This has the advantage that, during the processing carried out, no slag is generated in the forming mold, which must be separated therefrom due to the applied inertial forces. This shortens the process duration. Such a semi-finished product can be, for example, a rod or a hollow rod.

[0022] Connected to such a reaction vessel or part of such a reaction vessel may also be a plurality of forming dies as collecting volumes, into which the molten metal flows due to the inertial forces acting thereon. In particular, if smaller semi-finished products or workpieces are required, a plurality of such forming dies may be provided in a single melting process.

[0023] In the above method, if it is not a simple metal but an alloy that should be melted as the metal to be extracted, a variety of different crushed raw materials can also be provided. Recycled materials (recycling waste) can also be added to the raw materials. This can be an alloy forming material completely. In another method embodiment, it is stipulated that the reactant contains one or more alloying elements, which either exist as simple substances or exist in a combined form, and the metal to be extracted from the raw materials forms a compound with it. This is just beneficial for high melting point metals. Like this, in a single melting process (under the ignition of the exothermic reaction of the specification), almost any alloying element can be used to produce Ti, Ni, Cr and other high melting point alloys.

[0024] The bulk material mixture introduced into the reaction vessel can be present in a graded manner in the reaction vessel. This graded manner is usually achieved in the direction of the inertial forces acting on the metal when it is melted. This can be, for example, different mixing ratios of the individual components contained in the bulk material mixture and certain raw materials or additives are not evenly distributed in the bulk material mixture over the height of the reaction vessel. Since the metal is extracted by a direct route using this method, graded materials can also be easily produced using this method.

[0025] According to the size of the reaction vessel, in particular its height or its extension in the direction of the inertial force acting thereon and the volume of the bulk material-material mixture, the exothermic reaction process is carried out in a relatively short time. According to the above situation, this process can be completed in tens of seconds. Even for a larger volume of bulk material-material mixture, only a few minutes of reaction time is required. The melting of the one or more metals and their crystallization (hardening) must be included in this calculation. What must be considered in the combustion time and the migration of the heat front through the bulk material-material mixture is that the inertial force acting on the reaction vessel and its contents during the reaction process makes the molten metal and slag complete the required separation in the direction of the inertial force acting thereon within the entire extension range of the reaction vessel. This flow path of the molten metal also leads to the homogenization of the melt, which is particularly important if a metal alloy is to be melted from different raw materials. In one embodiment of the method, it is provided that the reaction vessel is equipped with an insulating effect, whereby the heat generated in the reaction vessel by the exothermic reaction is retained at a temperature level at which the metal to be extracted has not yet hardened for a longer time than the reaction actually occurring in the reaction vessel. Therefore, the extraction rate from the raw materials used can be improved using this method.

[0026] The reaction vessel is usually inert to the elements or compounds present in the bulk material mixture. Generally, it is undesirable for elements to dissolve out of the reaction vessel and enter the melt during the exothermic reaction.

[0027] The relatively low inertial forces provided in the method compared to previously known methods make the method scalable, in particular so that the amount of metal extracted per batch can be large enough for the economic use of the method. With the above forces, it is entirely possible to produce samples of several tens of kilograms or even several hundred kilograms in a reaction vessel. It is also entirely possible to use reaction vessels that can be used to produce semi-finished products or castings of greater weight.

[0028] The peculiarity of this method is that the metal extraction process is influenced by two key control variables, and more precisely the temperature at which the exothermic reaction is initiated, and the inertial forces. The viscosity of the molten metal can be influenced by its temperature. Basically, if the viscosity of the molten metal is low, the separation process requires less inertial forces. The temperature and inertial forces of the metal melting and separation process depend on the metal to be extracted and on the design of the part of the reaction vessel into which the molten metal flows.

[0029] In order to melt the metal from the oxides used as raw materials, different temperatures are required depending on the metal. The exothermic process for melting the metal or metal alloy can be influenced by physical parameters such as the particle size of the comminuted raw materials, the inertial forces acting on the bulk material-material mixture, the degree of compaction or the provided pore volume and the design of the reaction vessel. The smaller the particle size, the shorter the time required to extract the molten metal from it can be arranged. The inertial forces can also influence the migration speed of the heat front through the bulk material-material mixture in the reaction vessel and the reaction temperature. The higher the inertial force, the faster the heat front migrates through the bulk material-material mixture. If a higher inertial force is provided by the centrifuge, as is usually the case, the higher inertial force will influence the reaction temperature, because the resulting cooling effect is greater at higher rotational speeds.

[0030] By means of the degree of compaction (compaction), the intensity and duration of the exothermic reaction on the individual particles and the transport speed of the molten metal into the collecting volume can be influenced. The size and design of the collecting volume provided for collecting the liquid melt influence the cooling rate or cooling curve of the molten metal collected therein. It can of course be provided that the collecting volume and the bulk material mixture introduced therein are preheated, for example to a temperature of 500° C. to 600° C., before the exothermic reaction begins. The portion of molten metal that is first collected therein then cools down correspondingly more slowly on the preheated inner wall of the container serving as collecting volume, with the result that the crystal structure of the collected metal is overall more homogeneous.

[0031] The metal extraction process can also be affected by the composition or additives of the reactants and thereby chemically. For example, it can contain oxides for increasing or decreasing the reaction temperature. Other reactant components can be used to delay the exothermic reaction. For example, additives that can be used to increase or decrease the melting temperature of the slag can be used. The materials used for such purposes (usually oxides) are usually inert relative to the metal to be extracted. CaO can reduce the slag melting temperature, and MgO can increase the slag melting temperature. When a metal with a relatively low melting temperature is to be extracted, CaO is used. 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 melting temperature of the slag.

[0032] The particle size of the raw materials and reactants also influences the energy control of the course of the melt reaction in the reaction vessel. The smaller the particle size, the faster the reaction of each particle occurs. In this respect, the reaction of particularly exothermic substance mixtures can be delayed by providing a larger particle size. A larger particle size has a positive effect on the upstream comminution process, since this can be carried out in a correspondingly shorter time. This means that the particle size is also used in a clever way for energy control.

[0033] The abovementioned factors ensure that the method is scalable and can therefore also be carried out in a controlled manner in larger batches (eg 10 to 200 kg), in particular wherein consistent results are obtained.

[0034] The above statements clearly show that the method differs from the extraction methods currently used in industry not only in the significantly lower number of method steps, but also in particular in the significantly increased energy efficiency due to this. In addition, the potential of the ore as a raw material can be better utilized. In addition, emissions, especially CO2 emissions, are also significantly reduced. For example, in terms of energy use, the energy use in the production of Ni extraction is reduced to about 20% and CO2 emissions are reduced to about 30%. The same applies to all other alloys.

[0035] Reference below Figure 1 The flow chart in the figure uses an example to explain the invention. The application of the method according to the invention for direct extraction of Alloy 600 alloy (EN 2.4816) is described below. The method according to the invention produces a NiCrFe alloy with the following composition: Cr 15% by weight, Fe 8% by weight, the remainder Ni and unavoidable impurities, the total amount of which is less than 1%. This refers to the alloy also known as Alloy 600 (EN 2.4816).

[0036] NiOCr2O3 and Fe2O3 are mainly used as starting materials. In this embodiment, they are crushed together to a particle size of about 85μm (step 1). In this embodiment, Al is used as a reactant. Similarly, Mg, Si or a mixture (usually together with a conventional flux) can also be used as a reactant. The relevant raw materials are crushed to a particle size of 70μm (also step 1). In a subsequent step (process step 2), the raw materials and reactants are mixed together. An industrial mixer is used for this purpose. A mixing process is carried out, whereby as little energy as possible is introduced into the mixture by mixing. Both the crushing process and the mixing process are carried out by dry methods.

[0037] Then the bulk material-material mixture taken out from the mixer is filled into the reaction vessel 1 (step 3). In terms of its design, the reaction vessel 1 shown in the figure should only be understood as an exemplary embodiment of the reaction vessel. The reaction vessel 1 includes a lower part 2 designed as a forming mold. At the end of the extraction process, there is an alloy hardened as a casting ingot in this part of the local. The lower part 2 is incorporated into the upper part 4 in the direction of the filling port 3 of the reaction vessel 1. In terms of diameter, it is larger than the diameter of the local 2 used as a forming mold. After filling the reaction vessel 1, the bulk material-material mixture present therein is compacted on an oscillating plate (step 4). By this measure, the pore volume of the material mixture present in the reaction vessel 1 is reduced to about 20%. In the embodiment shown, the compacting step is carried out in two stages. In the first compacting stage, the reaction vessel 1 filled with the bulk material-material mixture 5 is compacted for 10 minutes with a sinusoidal vibration of 50Hz and an oscillation force of about 375N / kg. The compaction of the second compacting stage is carried out with a higher frequency and a higher oscillation force (125Hz; 575N / kg). In addition, in the second compaction stage, an axial force, and more precisely a low pressure of about 18 N / kg, is applied to the bulk material mixture 5 present in the reaction vessel 1. The second stage of the compaction step is carried out over a period of 20 minutes.

[0038] Subsequently, the reaction vessel 1 is connected to the reaction vessel support of the centrifuge (step 5). The centrifuge is operated so that an inertial force of about 85G acts on the reaction vessel 1 and its contents, as shown by the box arrow. When the required inertial force is reached, an exothermic redox reaction (step 6) is initiated to melt the metal. In the embodiment shown, this is accomplished by introducing a laser beam from the direction of the rotation axis of the centrifuge into the reaction vessel opened in the opposite direction of the inertial force. Due to the temperature generated, the metal melts from the raw material. As shown in the process steps in the figure, the combustion started on the surface of the bulk material-material mixture 5 on the filling port side continues in the direction of the inertial force acting. Due to the inertial force, the molten metal follows the moving heat front and flows into the lower part 2 of the reaction vessel 1. Due to the low density of the slag produced in the process, the effective separation between the metal alloy to be extracted and the slag produced in the process is caused. Once the combustion and separation process (step 7) is completed, the centrifuge is stopped, the reaction vessel 1 is taken out and cooled. The reaction products layered in the reaction vessel 1 - the casting 6 and the slag 7 - can then be taken out and separated from each other. The casting 6 is a high-purity Alloy 600 casting which has a cylindrical shape in the embodiment shown (step 8 ).

[0039] In connection with the exothermic reaction, the following reactions occur during the production of Alloy 600:

[0040]

[0041] To produce one kilogram of extracted alloy (Alloy 600) using the method steps described above, 0.4 kW / kg of energy is used. The metal extraction process is CO2-neutral, so the CO2 footprint per kilogram of extracted alloy in the method is 0 kg. If the entire value chain including ore processing is taken into account, 19.8 kW / kg of energy is required when using the method according to the invention. The CO2 footprint per kilogram of extracted alloy is 4.2 kg. In comparison, the energy consumption of conventional industrial extraction of this alloy is 124 kW / kg; the CO2 footprint per kilogram of extracted alloy is 13.4 kg. This illustrates the advantages of the method compared to conventional industrial melt metallurgical extraction routes. In addition, the time required to carry out the method is significantly reduced compared to conventional industrial extraction routes.

[0042] The description of the invention clearly shows that, using this method, high-melting-point metals (including metal alloys) can be extracted directly from ores as semi-finished products or workpieces. This extraction route can also be used in particular for extracting highly alloyed metals, which can be extracted in a single method step compared to conventional methods. In the method, the alloy is adjusted by the raw materials used and / or by additives (e.g. scrap made of the desired alloying components). It should also be emphasized that the molten metal has a particular homogeneity, especially when it is an alloy.

[0043] The invention has been described above using embodiments. Without departing from the scope of the applicable claims, many other implementation possibilities exist for the skilled person, without explaining them in detail.

[0044] Reference numerals list

[0045] 1 Reaction vessel

[0046] 2 Local

[0047] 3 Filling port

[0048] 4 Local

[0049] 5. Loose material - material mixture

[0050] 6 cast

[0051] 7 Slag

Claims

1. A method for extracting refractory metals, wherein the metal to be extracted is extracted from a raw material by a redox reaction which is exothermic in terms of its energy balance via the following steps: - providing a comminuted raw material consisting of or containing the metal to be extracted in oxidic bound form, - providing as bulk material a reactant which reacts exothermically after ignition, which reactant consists of or contains a slag former having a higher affinity for O2 than the metal to be extracted, - providing a bulk material mixture (5) from the raw materials and the reactants, - filling a batch of bulk material mixture (5) into a heat-resistant reaction vessel (1) while retaining the 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) through the introduction of mechanical vibrations, - applying inertial forces acting on the reaction vessel (1) and its contents, - by locally supplying heat energy to the bulk material mixture (5) starting from the edge of the bulk material mixture (5), an exothermic reaction of the bulk material mixture (5) is initiated during the action of inertial forces on the bulk material mixture (5), so that the metal to be extracted is melted and the molten metal is separated from the slag (7) due to the inertial forces acting during the ongoing redox reaction, - after the redox reaction is completed, the inertial forces acting on the reaction vessel (1) and its contents cease, and - After the contents of the reaction vessel have cooled, the reaction products (6, 7) are removed from the reaction vessel (1) and the extracted metals are separated from the slag (7).

2. A method for extracting high melting point metals, wherein the metal to be extracted is extracted from a raw material by a redox reaction which is exothermic in terms of its energy balance via the following steps: - providing a comminuted raw material consisting of or containing the metal to be extracted in oxidic bound form, - providing as bulk material a reactant which reacts exothermically after ignition, which reactant consists of or contains a slag former having a higher affinity for O2 than the metal to be extracted, - providing a bulk material mixture (5) from the raw materials and the reactants, - filling a batch of bulk material mixture (5) into a heat-resistant reaction vessel (1) while retaining the pore volume, - applying inertial forces acting on the reaction vessel (1) and its contents, - by locally supplying thermal energy to the bulk material mixture (5) starting from the edge of the bulk material mixture (5), an exothermic reaction of the bulk material mixture (5) is initiated while inertial forces act on the bulk material mixture (5), so that the metal to be extracted melts and the molten metal is separated from the slag (7) which is at least partially melted due to the heat input due to the inertial forces acting during the ongoing redox reaction, - after the redox reaction is completed, the inertial forces acting on the reaction vessel (1) and its contents cease, and - After the contents of the reaction vessel have cooled, the reaction products (6, 7) are removed from the reaction vessel (1) and the extracted metals are separated from the slag (7).

3. The method according to claim 2, characterized in that After a batch of the bulk material mixture (5) has been filled into the reaction vessel, the pore volume of the bulk material mixture (5) introduced into the reaction vessel (1) is reduced by compacting the bulk material mixture (5) by introducing mechanical vibration.

4. The method according to any one of claims 1 to 3, characterized in that The reactant is pulverized to a particle size of 10 μm to 500 μm to provide the raw material.

5. The method according to any one of claims 1 to 4, characterized in that The particle size of the reactant is 50 μm to 500 μm.

6. The method according to any one of claims 1 to 5, characterized in that In order to produce the bulk material mixture (5), comminuted raw materials and reactants are mixed in a closed mixing container, preferably without introducing energy into the mixture.

7. The method according to any one of claims 1 to 6, characterized in that The reaction vessel ( 1 ) containing the bulk material mixture ( 5 ) is subjected to the subsequent process steps in the reaction vessel ( 1 ) while retaining a pore volume of 10% to 30%.

8. The method according to any one of claims 1 to 7, characterized in that The bulk material mixture ( 5 ) is introduced into the reaction vessel ( 1 ) in graded form with respect to its various components.

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

10. The method according to claim 9, characterized in that The inertial forces are exerted using a centrifuge having a plurality of reaction vessel holders, of which in each case two are arranged diametrically opposite one another relative to the axis of rotation.

11. The method according to any one of claims 1 to 10, characterized in that The exothermic reaction is initiated by a resistive heating element and / or by a laser beam.

12. The method according to any one of claims 1 to 11, characterized in that The part (2) of the reaction vessel (1) in which the molten metal is collected during the exothermic reaction taking place also serves as a shaped collecting volume for the metal to be extracted, wherein the molten metal hardens in a manner replicating the cavity of the collecting volume.

13. The method according to any one of the preceding claims, characterized in that The reaction vessel (1) is filled in such a way that a collecting volume connected thereto and provided for collecting molten metal is not filled with the bulk material mixture (5), but is instead a volume present only in the direction of the filling opening, wherein in order to keep the collecting volume free, a bulk material mixture barrier is used which allows the molten metal to pass through and serves 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 provided to be made of a heat-resistant material, for example as a ceramic filter or as a screen made of 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 collection volume consists of a metal which is also contained in the metal to be extracted or consists of the metal to be extracted.

16. The method according to any one of claims 1 to 15, characterized in that The reactant is also a slag forming agent.

17. The method according to any one of claims 1 to 15, characterized in that The reactants include a slag forming agent.

18. The method according to any one of claims 1 to 17, characterized in that One or more of the elements Al, Mg and / or Si are used as reactants.

19. The method according to any one of claims 1 to 18, characterized in that The exothermic reaction of the bulk material mixture (5) in the reaction vessel (1) is initiated at various points.

Images