AT509526B1 - METHOD AND DEVICE FOR PREPARING METALS FROM THEIR OXIDES - Google Patents

Description

Austrian Patent Office AT509 526B1 2012-01-15

Description: The present invention relates to a method and an apparatus for producing metals from their oxides.

Titanium is not reduced according to the prior art for thermodynamic reasons with conventional reducing agents such as coal or hydrogen from its oxide, but gained over more complex processing. Thus, titanium dioxide is preferably converted into TiCl4, purified by distillation and reduced with magnesium to the metal.

In the case of obtaining titanium, the so-called " Kroll process " State of the art. This was developed in the mid-1950s and is still the best method for obtaining titanium metal, as it can produce absolutely pure, oxygen-free titanium. Even small traces of oxygen lead to a drastic deterioration of the mechanical properties of the metallic titanium. Although there have been efforts for more than 100 years to represent titanium and silicon over a simpler and less expensive electrolysis process, and Kroll himself prophesied a successful electrolytic process for titanium production in 1953 for the next 15 years, no such process has yet been established. See, for example, P.C. Turner, A. Hartman, J.S. Hansen and S.J. Gerdemann, " Low Cost Titanium Myth or Reality ", Technical Report, DOE / ARC-2001-086.

Recent scientific publications such as G. Chen, D. Fray and T. Farthing, Nature 407, 362 (2000), have stimulated a re-examination of the electrolysis processes. As a result, the name " FFC Cambridge Process " as noted, for example, by M. Ma, D. Wang, W. Wang, X. Hu, X. Jin and G. Chen, Journal of Alloys and Compounds 420, 37-45 (2006).

In most publications on the electrolytic production of titanium, the possible economic benefits are described. Equally interesting is the principal application of the process to the reduction of other oxides. For example, in the literature, the preparation of Si from SiO 2 is described (see, e.g., K. Yasuda, T. Nohara, R. Hagiwara and Y.H. Ogata, Electrochimica Acta 53, 106-110 (2007)). The experimental procedure for obtaining Si from SiO 2 differs from Ti recovery in that, in the latter case, porous TiO 2 pellets were contacted via the cathode (eg, a Kanthai wire) but, in the case of Si recovery, compact SiO 2 flakes ,

In the case of titanium is obtained after successful electrolysis a porous titanium sponge, which is contaminated with CaO and partially reduced Ti02 phases, so-called Magneli phases of the composition Tin02n-i (4 <n <10). Magneli phases are electrically conductive and have been the subject of electrochemical research, since they offer themselves as alternative electrode material for various electrochemical processes (M. Zweynert, H. Döring, J. Garche, K. Enghardt and K. Wiesener, Chemie Ingenieur Technik 70 ( 7/98), 827-841 (1998)). The titanium resulting from the FFC-Cam-Bridge process must therefore be freed from CaCl 2 and CaO as well as partially reduced titanium oxides in subsequent purification steps.

After a detailed literature search, it turned out that the principle of the production of titanium from a CaCl 2 melt has been known since 1903 (DE 150,557). Wilhelm Borchers and Wilhelm Huppertz from Aachen describe the production of metallic titanium from TiO 2 in a CaCl 2 melt. They suspected the reaction mechanism already in the primary cathodic deposition of metallic calcium, which in turn reduces the TiO 2. Thus, the following is stated in this patent: "The electrolysis is now continued until, according to the amount of electricity used, it can be assumed that all of the titanium oxide introduced has been reduced to titanium by the presumably primary electrolytically deposited alkaline earth metal and the amount of the Titanium has become so high in registered oxides that, in view of the prevention of corrosion, the Austrian patent office AT509 526 B1 2012-01-15

Power losses by re-dissolution about with the anode coming into contact Titans an interruption of the enterprise appears necessary. The assumption that the electrolytically formed calcium represents the actual reducing agent is not discussed in detail in the patent DE 150,557, but has its reason probably in two extremely revealing works by Wilhelm Borchers and Lorenz Stockem, which they a year earlier in the &quot; Journal of Electrochemistry &quot; (Borchers and L. Stockem, &quot; Metallic Calcium Obtaining Process &quot;, Journal of Electrochemistry 8, 757 (1902); W. Borchers, L. Stockem, &quot; The Electrodeposition of Pure Strontium &quot;, Journal of Electrochemistry 8 , 757 (1902)). This work describes the electrolytic production of pure calcium or strontium from the chlorides. The authors emphasize the importance of temperature control in the production of calcium, since metallic calcium forms just above the melting temperature of calcium chloride, but when heated further dissolves again and thus can not be removed from the melt (by means of crucible tongs). The temperature should therefore not be set too high for calcium recovery.

In the patent DE 150,557 for the production of titanium, the authors mention the use of the same (or a similar) apparatus as have already been described in the publications from the year 1902: "calcium chloride or other halogen salts, of course, mixtures thereof , are subjected to electrolysis under similar conditions and in similar apparatuses as those reported by Borchers and Stockem for the electrolytic deposition of calcium and strontium, and during the electrolysis the titanium oxide to be reduced is introduced into the melt in such a way that it should as far as possible immediately comes into contact with the cathode. Instead of introducing this oxide only during the electrolysis, it can already be in the vicinity of the cathode when assembling the mentioned apparatuses in order to then start the electrolysis of the molten alkaline earth halide salts in a known manner. Now results from these findings and from the description of the FFC Cambridge process the following picture: Since the experiments must take place under exclusion of air, it is reasonable to suppose that in addition to the currently known FFC-Cambridge process, all previously performed experiments 1) Construction of the Furnace 2) Insertion of the Electrodes [0013] 3) Introduction of the TiO 2 around the Cathode [0014] 4) Filling with CaCl 2 5) Air termination [0016] FIG ) Melting of the CaCl 2 7) Electrolysis 8) End of the electrolysis / cooling 9) Discharge of the products and work-up.

This type of experimental design is in principle the most convenient, since air contact can be avoided by suitable encapsulation of the furnace in a simple manner. In any case, Borchers and Huppertz mention in DE 150,557 the principal possibility of introducing the TiO 2 during the electrolysis. However, they indicate that the Ti02 must be placed near the cathode. Probably, however, they also co-tamped the Ti02 around the cathode in the experimental setup at the beginning, as otherwise a much more elaborate apparatus would have been described, in which titanium oxide would have been able to be introduced into the melt under exclusion of air. In the FFC Cambridge process, &quot; cathodic pre-forms &quot; prepared from mixtures of CaCl 2 and TiO 2 and used as pellets. Therefore, the following picture emerges for the reaction mechanism: If the TiO 2 is introduced in the vicinity of the cathode, as described in Borchers and in the FFC Cambridge process, then During the electrolysis process, calcium first forms on the surface of the cathode, which in turn reduces adjacent titanium dioxide via intermediates to titanium. However, the emerging metallic titanium also forms an electrical conductor that acts as a new cathode. Likewise, the partially reduced titanium oxides (Magneli phases) can serve as an electrically conductive electrode. However, this means that both the type of cathode and the size of the cathode surface changes during the electrolysis process. The surface of the new cathode is many times larger, since a porous body of titanium oxide is reduced. Thus, a porous body of reduced and partially reduced titanium oxide with a high surface area is formed around the original small-surface metal cathode. In any case, the production of electrolytically newly formed calcium shifts to the surface of this newly formed porous body. A return transport of calcium formed on the surface in the porous body seems rather unlikely.

Furthermore, the enlargement of the cathode surface is to be considered, since Borchers and Stockem emphasized as early as 1902 that a small cathode surface and a large anode surface were important. This means that the current density at the cathode is critical to calcium production in this process. This would also be consistent with the doctrine of general electrochemistry.

Another difficulty of all known methods is that the end of the electrolysis is difficult to determine. In fact, several processes occur simultaneously: Cathodic calcium production at the Kanthai cathode, calciothermal reduction of the metal oxide (TiO 2) to metal (titanium), calciothermal reduction of the metal oxide (TiO 2) to intermediates (Magneli phases), calcium evolution to new formed metal (titanium or Magneli phases), the anodic chlorine evolution and possible anodic reoxidations of titanium and calcium (especially to the oxides). The end of the electrolysis, however, is estimated by the absorbed amount of electricity and based on experience, and thus can hardly be determined exactly.

The BHP Billiton Innovation PTY Ltd. discloses in several patent applications various processes for the electrolysis of metal oxides using an electrolyte such as CaCl 2. WO 2005/38092 A1 describes a process in which pellets of the metal oxide are passed continuously or semicontinuously through a (CaO-containing) calcium chloride bath while being reduced therein. The consumed electrolyte, i. CaCI2, is constantly being supplemented, withdrawn via an overflow weir, cleaned outside the bath and re-cycled. For this purpose, preferred mass flows of the electrolyte (&quot; 70 to 100% of the amount of metal oxide &quot;) are indicated. Due to the (semi) continuous nature of the process, however, there is no reference in this disclosure to the end of the electrolysis or to the stoichiometry. In WO 2006/00025 A1, essentially the same process is described in which, however, finished or semi-finished products are produced. In addition, it has been found by the present inventors that the chloride content is less disturbing than previously thought. Once again there is no indication of the stoichiometry of the electrolysis reaction. And WO 2005/90640 A1 describes a method in which the metal oxide to be reduced is suspended in the liquid electrolyte and which is agitated or bubbled with an inert gas such that intermittent contact with the cathode occurs, thereby gradually reducing the metal oxide becomes. The stoichiometry is not addressed here.

The aim of the invention was therefore the development of a method by which the above disadvantages in the preparation of metals by reducing their oxides can be avoided.

This object is achieved in a first aspect of the invention by providing a method and in a second aspect of a device for carrying out the same, the method being a method for producing metals from their oxides by reduction by Austrian Patent Office AT509 526 B1 2012-01-15 of the metals in a CaCl 2 melt with dissolved therein metallic calcium as a reducing agent, which is formed in situ by electrolysis of CaCl 2, and is characterized by the following process steps: a) presentation of CaCl 2 and at least one to b) heating and melting of the CaCl 2, c) electrolysis of the CaCl 2 to form a be determined by measuring the electrolysis current, based on the amount of metal oxide to be reduced stoichiometric amount of metallic calcium and subsequent interruption the current supply, d) dissolving the metallic calcium by heating the mixture of CaCl 2 and calcium to a temperature above the melting point of calcium, e) displacing the at least one metal oxide in the calcium-containing CaCl 2 melt and

Reduction of one or more of the metals contained in the at least one metal oxide, f) removal of excess CaCl 2 and CaO formed in the reduction

Dissolution in water or aqueous acid.

In the process according to the invention, therefore, the metallic calcium is produced at a temperature which is only barely, i.e., at a temperature which is barely. only a few, e.g. 1 or 2, degrees, above the melting point of CaCl 2, formed around the cathode, while the metal oxide to be reduced is still stored separately from it. Subsequently, the power supply is interrupted, the calcium is melted by further heating and dissolved in the CaCl 2 melt. Only now, the at least one metal oxide to be reduced is added to the melt and preferably thoroughly mixed with the melt, while the redox reaction proceeds with the calcium metal and forms the desired at least one metal.

In this way, in the optimum case in the product mixture exclusively CaCl 2, CaO and the at least one desired metal are included. In practice, however, it is preferred to form a slight excess over the stoichiometric amount of calcium in order to quantitatively reduce the at least one desired metal from its oxide, since the excess metallic calcium in most cases is readily removed, e.g. by washing with water or dilute mineral acid from which at least one metal can be separated. Thus, even during the electrolysis, no new cathode is formed from the cathodically produced metal (s), since the electrolysis process in the metal oxide addition has already ended. This results in the following further advantages: [0035] optimum cathode current densities in primary Ca production; [0036] * no unreduced areas in an otherwise formed porous sponge; [0037] "no reverse reaction of the at least one formed metal at the anode; At least one metal falls in powder form, since no accumulation takes place around the Ka method.

The preferred thorough mixing of the at least one metal oxide and the CaCl 2 melt in step e) can be carried out in any desired manner, e.g. by stirring or tumbling the reaction mixture, for example, in the use of a rotary kiln according to the invention as a reaction vessel according to the later described second aspect of the invention.

The process according to the invention is in principle suitable for reducing oxides of the following elements: Sc, Y, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Re, Fe, Ru, Os, Co, Rh, Ir, Ni, Cu, Cd, Al, In, Si, Ge, Sn, Ce, Nd and Th, wherein due to a simplified handling preferably oxides of Sc, Y, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, In, Si, Ge, Sn, Ce, Nd and Th, more preferably oxides of Ti, Si, Th, V, Zr and Y are selected. The method is particularly suitable for the preparation of Ti and Si, especially due to the easy removability of Ca, CaO and CaCl 2 from the products by simply washing with water or dilute acids, especially some of the above metals can also be attacked by aqueous acid.

In general, it should be noted that the method is also useful for simultaneously obtaining more than one metal, such as metal alloys, e.g. Silicides, or of oxides of different composition than the starting materials, e.g. of Magneli phases, is suitable. Furthermore, instead of or in addition to metal oxides, it is also possible to use metallates, sulfides or phosphates as starting materials. Due to the difficult controllability of the redox reactions, inter alia due to the more difficult to detect stoichiometry and sometimes severely hampered isolation of the desired metals from the product mixture, however, the inventive method is preferably used to represent individual metals from their oxides.

The chlorine formed in the electrolysis of calcium is preferably trapped, inside or outside the container, the trapped chlorine being more preferably used to produce fresh CaCl 2 and / or HCl and therefore need not be disposed of expensively.

In a second aspect, as already mentioned, the invention also provides an apparatus for carrying out the method according to the invention, the apparatus according to the invention comprising: a rotary kiln which is rotatable by means of a motor and a reaction zone and spatially from the reaction zone comprises separate storage zone and the inner wall is provided at least in a partial region with a first electrode or formed as such, a projecting into the reaction zone second electrode, and at least one means for displacing contained in the storage zone material in the reaction zone. The reaction zone is preferably characterized by a &quot; well &quot; formed in the wall of the rotary tube, including a corresponding geometry, e.g. conical design or the like, the rotary tube is to be understood.

When carrying out the process in such a device, as will be described in more detail later, CaCl 2 is introduced into the rotary tube. In this case, the CaCl 2 can either be initially charged in the reaction zone or moved into it by rotation of the rotary tube. Calcium is reduced by the cathode protruding into the reaction zone, at least part of the rotary tube wall serving as an anode or being provided with such an anode. Thereafter, the power supply is interrupted and the at least one metal oxide from the storage zone is also transferred to the reaction zone to form the at least one desired metal.

Both the storage zone and the means for displacing material therefrom into the reaction zone can be designed as desired. In preferred embodiments, the bearing zone is a tubular extension of the rotary tube, which may either be symmetrical about the axis of rotation of the rotary tube or oblique to the axis of rotation of the rotary tube, or a platform located above the reaction zone within the rotary tube. Alternatively, various other installations in the rotary kiln come as storage zones in question, such as. Chambers, baskets, plates, trays, removable or destructible partitions, etc., as long as a spatial separation from the reaction zone to the completion of the calcium electrolysis is ensured.

The at least one means for displacing material contained in the storage zone into the reaction zone, hereinafter referred to as displacement means, is also not particularly limited and may be, for example, a single component or a single measure, e.g. In-motion setting of the rotary tube or parts thereof, or even a combination of several components and / or measures. Among other things, the nature of the means of displacement depends on the type and construction of the storage zone.

In the preferred case of a platform as a storage zone described above, for example, the drive may be a drive for rotating the platform, independent of the rotary tube, about a vertical axis, thereby reducing the load on the platform due to centrifugal force, material carried on the platform is removed from the platform and falls into the underlying reaction zone. Additionally or alternatively, the platform may include a pivoting or tilting mechanism for pivoting or tilting the platform about a horizontal axis, thereby again dropping the material stored on the platform into the reaction zone. When providing both features, as a rotary drive and pan or tilt mechanism thus both form a respective displacement means.

In the other preferred case of the tubular extension of the rotary tube described above as the bearing zone, the nature of the displacement means depends on the axial position of this extension. If it runs symmetrically about the axis of rotation, then the rotary kiln, preferably at one of its ends, can have a pivoting device for pivoting the rotary kiln about a horizontal axis. With sufficient inclination of the rotary tube, the material stored therein, which is usually the at least one metal oxide, slips out of the extension into the reaction zone. If, however, the tubular extension is inclined to the axis of rotation of the rotary tube, it is sufficient - at a sufficiently oblique angle, e.g. of 30 ° or more, or about 45 °, to rotate the rotary kiln by the motor 180 ° about its longitudinal axis, whereby the material in turn falls from the storage zone into the reaction zone. In the former case thus represents the pivoting means and in the second case, the engine of the rotary kiln, the displacement means.

In addition to the embodiments just described, but also alternatively, the at least one displacement means may also be a slider, wiper, piston or similar component and the material removed from the bearing zone by operation of this slider or the like. For example, a slider or piston may be provided at the end of a rotationally symmetric tubular extension serving as a bearing zone, e.g. a piston substantially covering the cross-section of the bearing zone, which either replaces the above-described pivoting device as a displacement means, or else amplifies its action as a further displacement means.

Also preferred according to the invention is the provision of a pressure relief valve on the rotary kiln in order to be able to discharge chlorine gas formed during the hydrolysis from the rotary kiln. Any other components in or on the rotary kiln are of course also possible, e.g. a further reaction zone in or outside of the rotary tube for producing fresh CaCl 2 from the formed chlorine gas and calcium therein e.g. is present as CaO, Ca (OH) 2 or CaCO 3, or also HCl, which can be used to remove CaO formed in the reaction. Such a reaction for the recovery of HCl can optionally take place in a H2 / CI2 fuel cell, by means of which, in addition to the formation of hydrochloric acid, electricity is simultaneously generated which can be used for driving and / or heating the rotary tube reactor.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a schematic representation of a preferred embodiment of the device according to the invention for carrying out the method according to the invention.

Fig. 2 shows the same embodiment of the device according to the invention of Fig. 1 in the upwardly pivoted position.

Fig. 3 is a schematic representation of another embodiment of the inventions to the invention device.

Fig. 4 shows the same embodiment of the device according to the invention from Fig. 3 in 180 ° rotated about the longitudinal axis position.

Fig. 5 is a schematic representation of another embodiment of the inventions to the invention apparatus. 6/16 Austrian Patent Office AT509 526B1 2012-01-15

DETAILED DESCRIPTION OF THE INVENTION

Hereinafter, the inventive method and apparatus for carrying it out with reference to the embodiments shown in the drawings will be described in more detail.

In a first step of the process of the invention, a defined amount of CaCl 2 is subjected to electrolysis in an oven under exclusion of air. By measuring the electrolysis current, after the efficiency of the calcium production was determined in advance, a defined concentration of metallic calcium in the melt can be generated here. By heating above the melting temperature of calcium, it completely dissolves in the CaCl 2 melt. The electrolysis is now interrupted and a stoichiometric amount of TiO 2 is introduced into the melt. The powdered metal oxide is reduced by the dissolved calcium in the melt. That only the calcium dissolved in the melt acts as a reducing agent and not the electrolysis current, for example, by the studies of M. Baba et. al reaffirmed. Thus, M. Baba, Y. Ono and R.O. Suzuki, Journal of Physics and Chemistry of Solids 66, 466-470 (2005), the successful calcio-thermal reduction of tantalum and niobium oxides in CaCl 2 melts. A difficulty in the process described is the addition and the homogeneous mixing of the metal oxide to be reduced in the melt with complete exclusion of air. Likewise, the metal oxide to be added must be brought to a certain temperature level before it is introduced into the melt.

These difficulties are solved by the inventive method by the electrolysis is carried out in a special reactor with exclusion of air. In Figs. 1-5, various embodiments of such a rotary tube reactor are referred to as so-called &quot; rotary tube electrolyzer &quot; represented, which serves to carry out the method according to the invention.

Figs. 1 and 2 show the same embodiment of the device according to the invention, in which a heated rotary tube 1 via a universal joint bearing 9 and a shaft journal about two axes, namely a horizontal and a vertical axis, is rotatably mounted. As a rotary tube drive is a motor 2, preferably an electric motor, which is turned off during the electrolysis. In the rotary tube 1, calcium chloride 6 is initially introduced in a region initially serving as a reaction zone. The rotary tube 1 is designed so that it serves as the anode 4 at least in this area, which is achieved either by using electrically conductive components of the reactor wall material, for which e.g. various (special) steels can be used, or by a coating of the wall with conductive material, such. Electric charcoal, can be done. By the execution of the rotary tube as tapering towards the ends of the cylinder is allowed to use only the inner wall until the beginning of the taper or even portions thereof as the anode by only selected areas, for example. be lined with electric charcoal. The reaction zone thus initially serves the area of the rotary tube 1 which is lowered in relation to the tapered sections.

Through the rotary tube wall, an electrode 5 protrudes galvanically separated from the Ano-deninnenraum in the calcium chloride 6, which serves as a cathode. In a tubular extension as a storage zone 3, which is positively and mechanically releasably connected to the rotary tube 1, the metal oxide to be reduced 7 is presented. As a mechanical connection between the main body of the rotary tube 1 and the tubular extension 3 is here a flange 10, which is shown in Fig. 2. As a support at the other end of the rotary tube is used at the beginning of the process and during the electrolysis a simple support 8. At the beginning of the process, via a suitable resistance circuit between the cathode and anode of the electrolyte, d.i. the CaCl 2 6, to a temperature above the melting temperature, i. above 772 ° C, to be heated. Similarly, the entire rotary tube 1 or the first reaction zone may be externally, e.g. be heated over burner. Subsequently, electrolysis is carried out by applying direct current until sufficient metallic calcium is formed, after which the electrolysis is terminated. The chlorine gas formed anodically in the electrolysis is passed out of the reactor via suitable outlet openings or collected within the rotary tube in a collecting vessel (not shown) and can be used for the formation of new calcium chloride, e. G. from CaCO3. Once the electrolysis is complete, the rotary tube 1 is reheated to melt the calcium formed and bring it into solution in CaCl 2. As the reactor is subsequently pivoted, preferably the entire rotary tube 1 should be heated to keep the calcium in solution during the subsequent redox reaction with the metal oxide.

In exothermic reduction reactions, such as e.g. the reduction of SiO 2 with metallic calcium at about 900 ° C, certain non-heated areas of the reactor can or must also be cooled. The necessity, the extent and the position of heating and possibly cooling can be determined empirically for the respective reaction system by the person skilled in the art without undue experimentation, wherein inter alia the added amount of metal oxide can also serve to control the reaction processes.

Fig. 2 shows the same embodiment of the device according to the invention after the subsequent pivoting about the horizontal axis. In the figure, an inclination angle of about 30 ° is shown, but it is any angle in which it is ensured that substantially all the metal oxide 7 from the extension 3 slips into the reaction zone of the rotary tube, which - depending on the Texture of the wall of the extension which eg may be provided with a sliding coating - about the angle of about 30 ° should be the case. Preferably, angles of about 30 ° to about 60 °, in particular an angle of about 45 °. However, the rotary tube 1 can also be pivoted by 90 ° and thus brought into a vertical position, so that the CaCI2 6 slips or falls into the (in Figs. 1 and 2: left) conically tapered region of the rotary tube, in the thus Also, the reaction zone, in which the reduction of the metal oxide is carried out by the previously formed calcium, would relocate and thus should also be made heatable.

The counter bearing of the rotary tube 1 can be done for example via a crane or ceiling construction. When tilted, the submitted oxide 7 slips into the melt. For optimal mixing of the melt with the oxide of the electric motor is now started to enable the rotary tube 1 in rotation and thus to ensure optimum mixing. In addition, the cathode 5 may be designed so that it can be operated as a stirrer in the form of a static mixer. The introduced metal oxide is now reduced to the metal, while calcium is again oxidized and forms CaO with the oxygen present.

From the cooled melt, the recovered metal can be recovered by removal of excess CaCl 2 by leaching with water. A further purification step is carried out by separating the CaO formed in the reaction, for example by dissolution with suitable acids.

Figs. 3 and 4 show an alternative embodiment of the device according to the invention, in which a similar rotary tube reactor 1, as shown in Figs. 1 and 2, is rotatably mounted only about its longitudinal axis, i. the pivoting device of the above embodiment is missing. In addition to the inscriptions of FIGS. 1 and 2, the respective shaft journal is denoted by 11 or 12 in FIG. 3 on both sides of the rotary tube 1. The pivoting device can be dispensed with, since in the embodiment shown here serving as a storage zone 3 tubular extension of the rotary tube 1, in which the at least one metal oxide 7 is presented, not rotationally symmetrical about its longitudinal axis, but to the latter obliquely (in Fig. 3: after below). 3 and 4, an exemplary angle of 30 ° is again drawn for this inclination, which, however, again - depending on the wall condition - is arbitrary selectable, as long as it is ensured that contained material in the subsequent 180 ° rotation, as shown in Fig. 4, substantially completely slips into the reaction zone of the rotary tube. Due to the lateral displacement to CaCI2 6 in the reaction zone in this case, an angle of 90 ° is of course not preferable. Rather, again, an angle of about 30 ° to about 60 °, in particular of about 45 °, is preferred. In FIG. 4, the embodiment of FIG. 3 is shown by rotation of the reactor 1 through 180 ° by means of the motor 2, whereby the oxide 7 to be reduced from the storage zone 3 slips into the CaCl 2 melt. The reaction zone for carrying out the two reactions, i. First, reduction of the calcium from the CaCl 2 and subsequent reduction of the at least one desired metal by the calcium, shifts in this embodiment, but here of a relative to the tapered constrictions lowered area of the reactor interior to the other, after rotation of the rotary tube 1 by 180 ° takes the position of the former.

After completion of the reduction of the at least one desired metal in the metal oxide 7 by the previously electrolytically reduced calcium, the flange connection can be dissolved again and the product mixture can be removed from the reactor.

Finally, Fig. 5 shows an embodiment of the device according to the invention in which, in carrying out the method according to the invention, a rotary tube reactor in an upright position, i. with vertical axis of rotation, is operated. The reactor is in turn similar in construction to the previously described embodiments. However, in this case, the calcium chloride 6 is completely introduced into a (tapered in Fig. 5: down) portion of the tapered at both ends rotary tube, which is why the wall of this section serves as an anode 4 for the electrolysis of calcium during the first redox reaction , As a logical consequence, the cathode 5 extends axially, from top to bottom, within a shaft journal (not shown) to the reaction zone, which does not shift in this embodiment. As a storage zone 3 is in this case a platform positioned inside the reactor on which the metal oxide 3 is presented and by means of a shaft 13 (within which the shaft journal, not shown) and a motor (not shown) is set in rotation.

The process of the method according to the invention is carried out substantially analogously to the cases described above. That is, the CaCl 2 6 is melted by heating the (lower) conically tapered portion, after which the electrolysis is carried out to produce metallic calcium. It is then reheated to melt the calcium and dissolve it in the CaCl 2, after which the platform 3 is rotated to force the metal oxide 7 laterally from the platform 3 due to the centrifugal force, so that it penetrates into the underlying melt falls.

Suitable values for the rotational speed can easily be determined empirically and depend - as was previously carried out for the angle of inclination - among other things, the surface texture of the platform, which may also be provided with a sliding coating or sloping down to the edge, and of the properties of the metal oxide (eg the grain size) from. Thus, a value of about 75 rpm may already be sufficient to convey substantially all of the metal oxide 7 by the centrifugal force from the platform 3 and into the melt. Preferably, values &gt; 500, more preferably &gt; 1,000, rev / min. Since the rotational speed of the rotary tube itself is by far far from sufficient to generate sufficient centrifugal forces on the platform 3, in the embodiment shown in Fig. 5, the rotary tube can be rotated during the entire process. Of course, however, the shaft 13 can also be kept static until the intended addition of the metal oxide 7 to the melt and rotated for this purpose.

In addition, or alternatively, to rotate the platform 3, however, it may also be provided with a pan or tilt mechanism which can be triggered from outside the reactor, which causes the metal oxide 7 to slip or fall from the platform 7 into the melt.

The invention will be described in more detail below with reference to a non-limiting specific embodiment.

EXAMPLE

In a reactor 1 as shown in Fig. 1, 50 kg of anhydrous CaCl 2 6 are presented and heated by means of gas burners from the outside to about 785 ° C. Then, between 9/16

Claims (19)

Austrian Patent Office 5 and anode 4 is applied a direct current and electrolyzed until a stoichiometrically sufficient amount of metallic calcium has formed in order to reduce the amount of titanium oxide 7 introduced in the tubular extension 3. The calcium formed initially deposits like a sponge around the cathode 5. After completion of the electrolysis, the power supply to the electrodes is mechanically separated and the temperature increased to about 800 ° C to 850 ° C, so that completely dissolves the previously formed, solid calcium in the calcium chloride melt. Subsequently, the rotary tube is raised and rotatably supported by a ceiling structure in a slanted position shown in FIG. When tilted, the submitted titanium oxide 7 slips into the melt. For optimal mixing of the melt with the oxide of the electric motor 2 is now started to enable the rotary tube 1 in rotation. The reaction mixture is then mixed for about 20 minutes. The endpoint control of the reaction can either be based on empirical values or can also be carried out by means of measurement and evaluation of the temperature profile of the redox reaction. After the melt has cooled, excess CaCl 2 is dissolved by adding water into the rotary tube 1 with further rotation of the tube. Finally, the flange connection 10 is opened and the content is transferred to further containers for further processing. Existing CaO is treated with dilute mineral acid, e.g. 0.01 n HCl, removed. It remains a moist sludge of fine-grained metallic titanium, which tends to self-ignite when dried in air. The sludge is therefore preferably dried in vacuo and stored under inert gas. 1. A process for the production of metals from their oxides by reducing the metals in a CaCl 2 melt with dissolved therein metallic calcium as a reducing agent, which is formed in situ by electrolysis of CaCl 2, characterized by the following process steps: a) presentation of CaCl 2 and at least b) heating and melting of the CaCl 2, c) electrolysis of the CaCl 2 to form a measured by measuring the electrolysis, based on the amount of metal oxide to be reduced stoichiometric amount of metallic calcium and a metal oxide to be reduced in the absence of air subsequent interruption of the power supply, d) dissolving the metallic calcium by heating the mixture of CaCl 2 and calcium to a temperature above the melting point of calcium, e) displacing the at least one metal oxide in the calcium-containing CaCl 2 melt and reducing one or me f) removal of excess CaCl 2 and CaO formed in the reduction by dissolution in water or aqueous acid. 2. The method according to claim 1, characterized in that the at least one metal oxide and the CaCl 2 melt in step e) are mixed. 3. The method according to claim 1 or 2, characterized in that the at least one metal oxide of oxides of Sc, Y, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, In, Si, Ge, Sn, Ce, Nd and Th is selected. 4. The method according to claim 3, characterized in that the at least one metal oxide is selected from oxides of Ti, Si, Th, V, Zr and Y. 5. The method according to claim 4, characterized in that the at least one metal oxide is selected from oxides of Ti and Si 6. The method according to any one of the preceding claims, characterized in that the chlorine formed in the electrolysis of calcium is trapped inside or outside of the container. 10/16 Austrian Patent Office AT509 526B1 2012-01-15 7. The method according to claim 6, characterized in that the trapped chlorine is used for the production of fresh CaCl 2. 8. A device for carrying out a method for producing metals from their oxides by reducing the metals as defined in any one of claims 1 to 7, comprising a rotary kiln (1) which is rotatable by means of a motor (2) and a reaction zone and one of the reaction zone spatially separated storage zone (3) and the inner wall is provided at least in a partial area with a first electrode (4) or designed as such, a projecting into the reaction zone second electrode (5) and at least one means for displacing in the storage zone (3) contained in the reaction zone. 9. Apparatus according to claim 8, characterized in that the reaction zone is formed by a depression in the wall of the rotary tube (1). 10. Apparatus according to claim 8 or 9, characterized in that the bearing zone (3) is a tubular extension of the rotary tube (1). 11. The device according to claim 10, characterized in that the tubular extension extends symmetrically about the axis of rotation of the rotary tube (1). 12. The device according to claim 10, characterized in that the tubular extension extends obliquely to the axis of rotation of the rotary tube (1). 13. The apparatus of claim 8 or 9, characterized in that the storage zone (3) is a above the reaction zone within the rotary tube (1) arranged platform. 14. The apparatus according to claim 13, characterized in that the at least one displacement means is a drive (13) for rotating the platform, independently of the rotary tube (1), about a vertical axis. 15. The apparatus of claim 13 or 14, characterized in that the at least one displacement means is a pivoting or tilting mechanism for pivoting or tilting of the platform about a horizontal axis. 16. Device according to one of claims 8 to 15, characterized in that the at least one displacement means is a pivoting device for pivoting the rotary kiln (1) about a horizontal axis. 17. Device according to one of claims 8 to 16, characterized in that the motor (2) serves as the at least one displacement means. 18. Device according to one of claims 8 to 17, characterized in that the at least one displacement means is a slide or wiper. 19. Device according to one of claims 8 to 18, characterized in that the rotary kiln (1) is equipped with a pressure relief valve. 5 sheets of drawings 11/16