WO2021047707A1

WO2021047707A1 - Method for thermochemically producing titanium

Info

Publication number: WO2021047707A1
Application number: PCT/DE2020/000212
Authority: WO
Inventors: Daniel Wolf
Original assignee: Daniel Wolf
Priority date: 2019-09-12
Filing date: 2020-09-11
Publication date: 2021-03-18
Also published as: DE112020004333A5; DE102020003440B4; DE102020003440A1

Abstract

The invention relates to a method and a device for thermochemically producing titanium. The method comprises at least the following method steps: providing gaseous titanium tetrachloride, involving a) providing a starting material having titanium dioxide, b) breaking down the starting material in mineral acid and forming a solution containing dissolved titanium (IV), c) precipitating an alkali metal titanium (IV) hexachloride out of the solution with an alkali metal chloride with the addition of hydrochloric acid or hydrogen chloride, e) heating the alkali metal titanium (IV) hexachloride and forming solid alkali metal chloride and gaseous titanium tetrachloride; reducing the gaseous titanium tetrachloride to form titanium trichloride, involving f) providing a reducing agent, g) reducing the gaseous titanium tetrachloride with the reducing agent and releasing chlorine to form titanium trichloride, wherein the reducing agent is oxidised by receiving chlorine, h) recycling the oxidised reducing agent obtained in method step g) via reduction and producing chlorine gas and/or oxygen, and providing the recycled reducing agent as the reducing agent in method step f); disproportionation of the titanium trichloride to form titanium and titanium tetrachloride, involving j) disproportionation of the titanium trichloride or of the titanium dichloride to form titanium and titanium tetrachloride, k) providing the titanium tetrachloride obtained in method step j) and optionally i) as titanium tetrachloride in method step g); and separating the obtained titanium.

Description

METHOD FOR THE THERMOCHEMICAL PRODUCTION OF TITANIUM

The present invention relates to a method for the thermochemical production of titanium and a device for the thermochemical production of titanium.

Processes for the production of titanium are known per se.

Numerous processes, some of them very old, are known for extracting metal from the corresponding ores. The successful extraction of metals through reduction with coal or with carbonaceous, fossil fuels is important. However, this releases carbon dioxide that has an impact on the climate. Likewise, a rediscovered approach for this purpose, using renewable carbonaceous biomass, such as charcoal for industrial applications, has the disadvantage of being dependent on large areas, to the detriment of particular ecosystems. Carbothermal reduction also fails with regard to some base metals, such as titanium, since the elements have too great an affinity for oxygen and the reaction only proceeds as far as the carbide under the usual conditions.

In addition, electrolytic metal extraction is an important process for extracting metal, for example in the case of aluminum. However, this requires comparatively large amounts of electricity. In the case of titanium, numerous innovations have been found in recent years that have made a largely direct electrolytic production increasingly possible. The disadvantage here, however, is often The raw titanium obtained has a very high oxygen content, a fact which leads to considerable problems with the properties of the material, as well as the often low current efficiency of electrolysis in the case of titanium.

The reduction discovered by Kroll with electrolytically obtained magnesium in a discontinuous and technically complex process with considerable energy requirements of around 85 kWh per kg of metal continues to be the current standard in the industry.

For some metals, direct thermolysis has been considered. However, depending on the metal, the necessary temperatures are extremely high and the problem of adequate material separation does not appear to be practically solvable, especially since quenching processes that are thermodynamically lossy have to be used.

SCHOSSBERGER, Frederic V .: A new process for titanium. In: Industrial and Engineering Chemistry, Vol. 51, 1959, No. 3, 669-670, describes a partial process for the production of titanium from potassium titanium (IV) hexachloride by reduction with magnesium.

No. 2,874,040 A describes a partial process for the production of titanium from titanium tetrachloride with hydrogen at a temperature above 1000 K, with titanium dichloride being disproportionated at a temperature above 2000 K to form titanium trichloride and liquid titanium in a final step.

Due to the importance of titanium and increased environmental awareness, there is an interest in providing a method for producing titanium which can be economical and which overcomes the ecological disadvantages of known methods.

It is therefore the object of the present invention to provide a method for producing titanium which overcomes at least some disadvantages of the previously known methods. In particular, it is the object of the present invention to provide a method for the production of titanium which can be carried out at a comparatively low temperature and whose energy requirement can be adequately covered by the supply of heat, in particular with solar thermal energy.

This object is achieved by the method according to claim 1. Furthermore, the object is achieved by the device according to claim 10.

Preferred embodiments of the invention are specified in the subclaims, in the description or the figures, wherein further features described or shown in the subclaims or in the description or the figures can represent an object of the invention individually or in any combination if they emerge from the Context does not clearly show the opposite. The invention proposes a method for the thermochemical production of titanium, comprising at least the following method steps:

Providing gaseous titanium tetrachloride comprising the process steps: a) Providing a starting material comprising titanium dioxide, in particular providing titanium dioxide and / or ilmenite, b) digesting the starting material in mineral acid, preferably in hydrochloric acid, at a temperature in a range greater than or equal to 25 ° C up to less than or equal to 135 ° C. with the formation of a solution, in particular an aqueous solution, comprising dissolved titanium (IV); c) precipitating an alkali metal titanium (IV) hexachloride from the solution with an alkali metal chloride while supplying hydrochloric acid or hydrogen chloride at a temperature in a range greater than or equal to -15 ° C to less than or equal to 30 ° C, the alkali metal being selected from the group consisting of lithium, sodium and potassium, d) Optional drying of the alkali metal titanium (IV) hexachlpride with hydrogen chloride at a temperature in a range greater than or equal to 30 ° C to less than or equal to 250 ° C, e) heating the alkali metal titanium (IV) hexachloride at a temperature in a range from greater than or equal to 340 ° C to less than or equal to 700 ° C with the formation of solid alkali metal chloride and gaseous titanium tetrachloride;

Reduction of the gaseous titanium tetrachloride to titanium trichloride comprising the process steps: f) providing a reducing agent, preferably selected from the group consisting of hydrogen gas and transition metal chloride, the transition metal chloride being selected from the group consisting of vanadium (II) chloride, iron (II) chloride, chromium (II) chloride, cobalt (II) chloride, nickel (II) chloride, copper (I) chloride, antimony (II) chloride, tin (II) chloride, and mixtures thereof, the transition metal chloride preferably being vanadium (II) chloride, g) Reduction of the gaseous titanium tetrachloride with the reducing agent with the release of chlorine to titanium trichloride at a temperature in a range from greater than or equal to 20 ° C to less than or equal to 440 ° C, the reducing agent being oxidized with the absorption of chlorine, h) recycling of the oxidized reducing agent obtained in process step g) by preferably thermal reduction with the formation of chlorine gas and / or acid substance and provision of the recycled reducing agent as reducing agent in method step f); Disproportionation of the titanium trichloride to titanium and titanium tetrachloride comprising the process steps: i) optionally disproportionation of the titanium trichloride to titanium tetrachloride and titanium dichloride at a temperature in a range from greater than or equal to 400 ° C to less than or equal to 800 ° C, j) disproportionation of the titanium trichloride or the titanium dichloride to titanium and titanium tetrachloride at a temperature in a range from greater than or equal to 600 ° C. to less than or equal to 1900 ° C., k) providing the titanium tetrachloride obtained in process step j) and optionally i) as titanium tetrachloride in process step g); and separating the obtained titanium.

The above-described method can advantageously ensure that no climate-affecting carbon dioxide has to be released during the production of titanium. Furthermore, it can advantageously be achieved that the titanium obtained is particularly pure. Furthermore, it was surprisingly possible to achieve that the method can be operated in such a way that the energy for the method is provided purely by solar energy. Compared to processes that can be operated indirectly via solar energy, such as electrolysis, the process can advantageously have a higher energy efficiency, since solar thermal energy can be used directly due to the process running in several stages.

The combination of the reactions shown also enables the process to be operated at temperatures below 1000 ° C. This makes it possible to use heat accumulators, for example molten salt or ceramic storage elements, and thus to achieve an economically advantageous continuous mode of operation, for example in the late hours. In the context of the present invention, a starting material comprising titanium dioxide is to be understood as meaning a starting material which has titanium dioxide, that is to say T1O ₂ , as a main component. This is to be understood as meaning that the starting material has titanium dioxide in a mixture and / or has a chemical compound which contains titanium dioxide.

In the context of the present invention, the term ilmenite is _{to be understood as the naturally occurring mineral with the empirical formula FeTiO 3} , which formally consists essentially of iron (II) oxide and titanium dioxide.

For the purposes of the present invention, the term hydrochloric acid is to be understood as meaning hydrochloric acid. This is to be understood as an aqueous solution of hydrogen chloride. For the purposes of the present invention, hydrogen chloride is to be understood as meaning the stoichiometric compound of chlorine and hydrogen.

A method described above is therefore used in particular for the thermochemical production of titanium.

In one embodiment, it can be provided that the dissolving from method step b) is carried out at a temperature in a range from greater than or equal to 40 ° C. to less than or equal to 120 ° C.

In one embodiment it can be provided that the precipitation of the alkali metal titanium (IV) hexachloride from process step c) is carried out at a temperature in a range from greater than or equal to 5 ° C. to less than or equal to 20 ° C. In one embodiment it can be provided that the drying of the alkali metal titanium (IV) hexachloride from process step d) is carried out at a temperature in a range from greater than or equal to 50.degree. C. to less than or equal to 250.degree.

In one embodiment it can be provided that the heating of alkali metal titanium (IV) tetrachloride from process step e) is carried out at a temperature in a range from greater than or equal to 500 ° C. to less than or equal to 600 ° C.

In one embodiment it can be provided that the reduction of the gaseous titanium tetrachloride from method step g) is carried out at a temperature in a range from greater than or equal to 50.degree. C. to less than or equal to 400.degree.

In one embodiment, it can be provided that the disproportionation of the titanium trichloride from method step i) is carried out at a temperature in a range from greater than or equal to 400.degree. C. to less than or equal to 600.degree.

In one embodiment, it can be provided that the disproportionation of the titanium trichloride or the titanium dichloride from method step j) is carried out at a temperature in a range from greater than or equal to 800 ° C. to less than or equal to 1900 ° C.

In detail, a method according to the invention initially comprises providing gaseous titanium tetrachloride. The provision of the gaseous titanium tetrachloride initially comprises process step a), provision of a starting material comprising titanium dioxide, in particular provision of titanium dioxide and / or ilmenite.

Thus, raw material usually used for the extraction of titanium can advantageously be used as the starting material for the process according to the invention. This means that the starting material can be procured in large quantities. This is followed by process step b), digestion of the starting material in mineral acid, preferably hydrochloric acid, at a temperature in a range from greater than or equal to 25 ° C to less than or equal to 135 ° C, forming a solution, in particular an aqueous solution, comprising dissolved titanium (IV ).

The digestion in mineral acid makes it possible to dissolve the titanium dioxide inexpensively, since mineral acids can be obtained inexpensively and in large quantities and little or no energy input is necessary, since the reaction is exothermic.

It can preferably be provided that the mineral acid is hydrochloric acid. As a result, it can advantageously be achieved that a high chloride ion concentration is already present for the subsequent steps.

It can preferably be provided that the hydrochloric acid has a concentration of greater than or equal to 8% by weight to less than or equal to 35% by weight, particularly preferably from greater than or equal to 15% by weight to less than or equal to 35% by weight , very particularly preferably from greater than or equal to 20% by weight to less than or equal to 28% by weight. In this way it can advantageously be achieved that the hydrochloric acid is sufficiently reactive and at the same time can be handled well. There is also the possibility of simple recycling, since any azeotropic concentration that occurs can be returned to the beginning of the process.

It can preferably be provided that the amount of the reactants is selected such that the solution obtained has titanium in a concentration in a range from greater than or equal to 2% by weight to less than or equal to 15% by weight, preferably greater than or equal to 3 , 5 wt. % to less than or equal to 14% by weight, particularly preferably greater than or equal to 5% by weight to less than or equal to 7% by weight.

It can preferably be provided that the temperature in process step b) is reached at the beginning by supplying heat.

It can preferably be provided that a chloride-containing salt, for example calcium chloride or magnesium chloride, is added in process step b). As a result, it can advantageously be achieved that the starting material comprising titanium dioxide is dissolved as completely and efficiently as possible.

It can preferably be provided that the reaction is mixed mechanically in process step b). If the starting material contains iron, for example ilmenite, the iron is separated off after process step b), the iron optionally being oxidized, reduced or precipitated, the iron being separated off. Preferably by precipitation, liquid-liquid extraction, in particular of III-valent iron chloride and / or ion exchange of iron (II) chlorides.

In a preferred embodiment, iron (III) chloride can be separated off by liquid-liquid extraction, preferably with amines, e.g. trioctylamine.

In a particularly preferred embodiment, in the case of ilmenite as the starting substance, iron (II) ions can be separated off on a solid or liquid ion exchanger. It can be provided that the ion exchanger is then regenerated with hydriodic acid and the iron contained in the following as Iron (II) iodide is present, which can be dried and broken down into elemental iron and lodine vapor by supplying solar heat at 1200 ° C.

The recycling of the iodine and renewed provision of the hydrogen iodide is preferably carried out in an aqueous disproportionation reaction, for example a known Bunsen reaction.

In an alternative embodiment, the separated foreign chlorides can be pyrolytically decomposed into hydrogen chloride and the corresponding metal oxides by supplying steam and introducing heat. These can then be used for further purposes.

Process step b) is followed in process step c) by precipitating an alkali metal titanium (rV) hexachloride from the solution with an alkali metal chloride with the addition of hydrochloric acid or hydrogen chloride at a temperature in a range from greater than or equal to -15 ° C to less than or equal to 30 ° C wherein the alkali metal is selected from the group consisting of lithium, sodium and potassium.

It can thereby be achieved that the titanium in the form of the alkali metal titanium (IV) hexachloride can easily be separated from the solution obtained in process step b). The separation can be achieved using a method known to the person skilled in the art. For example, the alkali metal titanium (IV) hexachloride can be separated from the solution by filtering, decanting or centrifuging. As a result of the low temperature, a particularly high proportion of the alkali metal titanium (IV) hexachloride can be achieved. In one embodiment it can be provided that the supply of hydrogen chloride takes place under excess pressure with heat dissipation at ambient temperature. As a result, as complete a precipitation as possible can be achieved at ambient temperature. It can preferably be provided that the alkali metal is potassium. It could be shown that potassium chloride is particularly suitable as an alkali metal chloride, since it forms potassium titanium (IV) hexachloride with titanium tetrachloride in the presence of hydrogen chloride, which can advantageously be separated from the solution by precipitation.

Alternatively, it can be provided that the alkali metal is lithium, sodium or potassium, if the solution is not an aqueous solution.

It can preferably be provided that the alkali metal chloride, in particular the potassium chloride, is added in an amount in a range from greater than or equal to 0.5% by weight to less than or equal to 45% by weight, particularly preferably greater than or equal to 15% by weight. % to less than or equal to 25% by weight, based on the total weight of the aqueous solution, comprising dissolved hydrogen chloride and dissolved titanium tetrachloride.

The addition can take place gradually in the course of a continuous process with precipitation or batchwise, preferably with stirring, for conversion to the insoluble hexachlorotitanate.

In one embodiment it can be provided that after step b) a liquid-liquid extraction takes place to purify the titanium tetrachloride. For example, in this case the use of a neutral extractant such as tributyl phosphate with decanol dissolved in a saturated C9-C17 hydrocarbon is particularly advisable. In a preferred embodiment, the hexochlorotitanate can be precipitated in step c) directly from and through contact with the organic phase respectively. In addition to water as the solvent, an anhydrous, polar solvent can also be used here.

After the titanium chloride has been separated off in process step c), the remaining solution can again be passed to step b) for renewed dissolution,

In process step d), the alkali metal titanium (rV) hexachloride is optionally dried with hydrogen chloride at a temperature in a range from greater than or equal to 30 ° C. to less than or equal to 250 ° C.

This means that the alkali metal titanium (IV) hexachloride is dried without reacting again to form titanium dioxide. Furthermore, the hydrogen chloride quickly absorbs water or solvent and additionally heats the alkali metal titanium (IV) hexachloride.

It can preferably be provided that the hydrogen chloride is provided in process step d) as a saturated solution in an anhydrous solvent or as a hydrogen chloride atmosphere.

It can preferably be provided that the hydrogen chloride in process step d) is anhydrous. This enables particularly efficient drying to be achieved.

It can preferably be provided that the hydrogen chloride from process step d) is regenerated and / or dried after process step d), the regeneration and drying preferably being carried out using solar-thermally regenerated calcium chloride, concentrated sulfuric or phosphoric acid.

It can preferably be provided that the hydrogen chloride is fed in in process step d) in countercurrent to the alkali metal titanium (IV) hexachloride. This can advantageously be achieved that the alkali metal titanium (IV) hexachloride particularly is dried quickly and has a particularly low water content after drying.

This is followed by process step e), which involves heating the

Alkali metal titanium (IV) hexachloride at a temperature in a range from greater than or equal to 340 ° C. to less than or equal to 700 ° C. with the formation of solid alkali metal chloride and gaseous titanium tetrachloride.

By providing gaseous titanium tetrachloride as described above, it can advantageously be achieved that, compared to the commonly used carbochlorination, fewer or no harmful chlorinated hydrocarbons are formed and no carbon dioxide is produced.

In one embodiment, it can be provided that the gaseous titanium tetrachloride is purified using known processes between process steps e) and f).

The steps described above provide gaseous titanium tetrachloride. In the next process step, the gaseous titanium tetrachloride is reduced to titanium trichloride.

As a result, it can advantageously be achieved that a subsequent disproportionation is made possible.

A reducing agent is first provided in process step f), preferably selected from the group consisting of hydrogen gas and transition metal chloride, the transition metal chloride being selected from the group consisting of vanadium (II) chloride, iron (II) chloride, chromium (II) chloride, Cobalt (II) chloride, nickel (II) chloride, Copper (I) chloride, antimony (II) chloride, tin (II) chloride, and mixtures thereof, the transition metal chloride being preferably vanadium (II) chloride.

This is followed in process step g) the reduction of the gaseous titanium tetrachloride with the reducing agent with the release of chlorine to titanium trichloride at a temperature in a range from greater than or equal to 20 ° C. to less than or equal to 440 ° C., the reducing agent being oxidized with the absorption of chlorine .

In this way it can advantageously be achieved that the reaction can proceed in a controlled manner and that no chlorine gas is released during the conversion to titanium trichloride. The reaction can thus be implemented particularly well. Furthermore, the correspondingly selected reducing agent makes it possible to work at particularly mild temperatures.

It can particularly preferably be provided that process step g) is carried out at a temperature in a range from greater than or equal to 135.degree. C. to less than or equal to 250.degree. C., preferably from greater than or equal to 200.degree. C. to less than or equal to 250.degree.

The titanium trichloride can advantageously be part of the oxidized reducing agent as a solid _. known methods, for example, can be separated by utilizing the different density.

In method step h), the oxidized reducing agent obtained in method step g) is recycled by reduction in a preferably solar-thermally operated cycle with the formation of chlorine gas and then oxygen and the recycled reducing agent is provided again as a reducing agent in method step f).

The invention provides for this reduction in particular by means of a thermochemically operated reaction sequence. As a preferred embodiment, the chlorine obtained is mixed with water or water vapor is converted into oxygen and hydrogen chloride in a reverse reaction according to Deacon. The hydrogen chloride can ideally be reintroduced into process steps b), c) and d). As a result, a cycle can advantageously be obtained, as a result of which there is almost no consumption of the substance necessary for reduction. In addition, it can be achieved that the heat generated and absorbed can be exchanged.

It can preferably be provided that the reduction in process step g) is catalyzed, particularly preferably by the action of UV-containing radiation or a catalyst. Preferably, it can be provided that the UV-containing radiation obtained from sunlight, for example by separation with Lichtfiltem, optical redirection and Eispeisung in the reactor can thereby advantageously be achieved that even at low temperatures of for example 25 ° C and corresponding TiCl ₄ vapor pressure and 2 bar hydrogen partial pressure under simple sunlight, the equilibrium position favored at low temperatures in the direction of TiCl ₃ under quartz glass is reached in a few minutes.

The reduction in process step g) is preferably carried out at temperatures in a range from greater than or equal to 120 to less than or equal to 200 ° C., and with an increased partial pressure of hydrogen and preferably also a slightly increased pressure of titanium tetrachloride. In addition, the titanium trichloride obtained is deposited in solid form and can be collected by a suitable mechanical device and removed from the reaction space. Alternatively, cyclic rinsing with liquid titanium tetrachloride can take place and the titanium trichloride is removed from the reaction chamber to allow further entry of the UV radiation. The trichloride can then be separated off from the liquid titanium tachloride, for example by filtration.

In one embodiment, hydrogen chloride gas formed in each case can be bound by appropriate, preferably anhydrous, absorbers and removed from the reactor, the unused hydrogen being returned again and subsequently being supplemented by new, thermochemically provided hydrogen.

In a preferred embodiment, the reaction can take place in the gas phase under strongly bundled UV radiation, a targeted supply of hydrogen gas along a quartz glass window, through which the radiation enters, preventing precipitation and clouding due to titanium trichloride.

As a result, the process steps described above reduce the gaseous titanium tetrachloride to titanium trichloride. The next step is the disproportionation of the titanium trichloride to titanium and titanium tetrachloride.

Optionally, in process step i), the titanium trichloride can be disproportionated to titanium tetrachloride and titanium dichloride at a temperature in a range from greater than or equal to 400 ° C. to less than or equal to 780 ° C., preferably from greater than or equal to 430 ° C. to less than or equal to 600 ° C. .

It can thereby be achieved that in the following step a lower amount of titanium tetrachloride is produced per amount of titanium obtained. The process can thus be controlled more easily in the following step and the separation of the titanium is facilitated. Process step i) can optionally also be dispensed with. As a result, one method step can advantageously be saved, as a result of which costs can be reduced. In process step j), the titanium trichloride or the titanium dichloride is disproportionated to titanium and titanium tetrachloride at a temperature in a range from greater than or equal to 580 ° C. to less than or equal to 1900 ° C. As a result, it can advantageously be achieved that the energy requirement for the production of the titanium is particularly low, because the disproportionation from titanium trichloride is energetically advantageous. Furthermore, it can be achieved in this way that the titanium can then be separated off particularly easily, since the titanium tetrachloride is volatile and can be easily removed.

The titanium tetrachloride obtained in process step j) and optionally i) is provided as titanium tetrachloride in process step g).

As part of the disproportionation in steps j) and i), traces of volatilized titanium and / or titanium trichlorides can be deposited at a slightly colder point, for example on the surface of the heat exchanger, as part of the removal of the titanium tetrachloride from the reaction area. These can preferably be released mechanically, for example by vibration or mechanical slides, and fed back into the reactor. As a result, it can be achieved more advantageously that as little titanium as possible is lost.

Finally, the titanium obtained is separated off.

The removal of the titanium can preferably be carried out by a method known to the person skilled in the art. The process thus describes the thermochemical production of titanium.

In a preferred embodiment, it can be provided that the reducing agent from process step f) is hydrogen gas and the reduction from process step g) is carried out at a temperature in a range from greater than or equal to 20 ° C. to less than or equal to 350 ° C., preferably greater than or equal to 350 ° C. or equal to 130.degree. C. to less than or equal to 240.degree. C., for example at 180.degree. C., the hydrogen gas being oxidized to hydrogen chloride with the absorption of chlorine, with the hydrogen chloride being mixed with vanadium (II) chloride with the formation of vanadium (III ) chloride is reduced to hydrogen gas at a temperature in a range from greater than or equal to 60 ° C to less than or equal to 390 ° C, preferably from greater than or equal to 160 ° C to less than or equal to 280 ° C, for example 200 ° C, where the Hydrogen gas is used again as reducing agent in process step f), and the vanadium (III) chloride is formed with the formation of chlorine gas by heating at a temp temperature in a range from greater than or equal to 460 ° C. to less than or equal to 700 ° C., preferably from greater than or equal to 560 ° C. to less than or equal to 580 ° C., for example 570 ° C., is recycled to vanadium (II) chloride. Depending on the reaction conditions, vanadium (IV) chloride is produced as an intermediate product on the way to decomposition to chlorine gas.

With hydrogen gas as the reducing agent, it can be provided in one embodiment that the reduction from method step g) is carried out at a temperature in a range from greater than or equal to 150 ° C. to less than or equal to 250 ° C., preferably from greater than or equal to 190 ° C. less than or equal to 210 ° C, for example at 200 ° C.

With hydrogen gas as the reducing agent, it can be provided in one embodiment that method step h) at a temperature in a range from greater than or equal to 250 ° C. to less than or equal to 390 ° C., preferably from greater than or equal to 300 ° C. to less than or equal to 340 ° C, for example 320 ° C, is carried out. With hydrogen gas as the reducing agent, it can be provided in one embodiment that the vanadium (III) chloride is formed with the formation of chlorine gas by heating at a temperature in a range from greater than or equal to 520 ° C. to less than or equal to 620 ° C., preferably greater than or equal to 560 ° G to less than or equal to 580 ° C, for example 570 ° C, is recycled to vanadium (II) chloride.

By using hydrogen gas as the reducing agent, it can advantageously be achieved that the titanium tetrachloride is reduced without introducing impurities, since the hydrogen chloride formed can be separated off again particularly effectively. The subsequent process management is thus facilitated and particularly pure titanium can be obtained.

In an alternative embodiment, it can be provided that the hydrogen gas was obtained by thermal, preferably solar-thermal, decomposition of water with the aid of cyclically heated mixed oxides, for example cerium oxide or the sulfur iodine cycle. In this case, the hydrogen chloride from process step g) would be returned to process step b) and c).

It can preferably be provided that the reducing agent from process step f) is hydrogen gas and the reduction from process step g) with a hydrogen partial pressure in a range from greater than or equal to 1 bar to less than or equal to 20 bar, for example 4 bar, at a temperature in one range from greater than or equal to 20 ° C. to less than or equal to 250 ° C., preferably less than or equal to 160 ° C., is carried out under the action of UV radiation. Provision can preferably be made for the vanadium (III) chloride to be recycled with the formation of chlorine gas separately for the provision of the reducing agent. It can preferably be provided that the reducing agent is provided via two separate devices, one device being used for the provision while in the other device, the vanadium (III) chloride is recycled with the formation of chlorine gas, and vice versa. As a result, it can advantageously be achieved that reducing agent can be continuously provided in method step f).

In an alternative preferred embodiment, it can be provided that the reducing agent from process step f) is vanadium (II) chloride and the reduction from process step g) is carried out at a temperature in a range from greater than or equal to 80 ° C to less than or equal to 420 ° C is, preferably from greater than or equal to 240 ° C. to less than or equal to 360 ° C., for example at 320 ° C., the vanadium (II) chloride being oxidized to vanadium (III) chloride with uptake of chlorine, in process step h) the the vanadium (III) chloride is reduced to vanadium (II) chloride with the formation of chlorine gas at a temperature in a range from greater than or equal to 460 ° C. to less than or equal to 800 ° C., preferably from greater than or equal to 590 ° C. to less than or equal to 660 ° C., for example 620 ° C., the vanadium (II) chloride preferably being provided as the reducing agent in process step f).

In this way, a particularly simple process control can advantageously be achieved, since the reducing agent can be recycled continuously.

With vanadium (II) chloride as reducing agent, it can be provided in one embodiment that process step g) is carried out at a temperature in a range from greater than or equal to 80 ° C. to less than or equal to 120 ° C., preferably greater than or equal to 95 ° C. to less than or equal to 105 ° C, for example at 100 ° C.

With vanadium (II) chloride as the reducing agent, it can be provided in one embodiment that method step h) at a temperature in a range of greater than or equal to 520 C. to less than or equal to 620.degree. C., preferably from greater than or equal to 560.degree. C. to less than or equal to 580.degree. C., for example 570.degree.

It can preferably be provided that the vanadium (III) chloride and the vanadium (II) chloride are present as sodium double salt. Thereby, a better decomposition property can be obtained.

It can preferably be provided that the vanadium (II) chloride is run in process step g) in countercurrent to the titanium tetrachloride. This enables a particularly high conversion of the reduction in titanium tetrachloride to be achieved.

It can preferably be provided that the chlorine gas from process step h) is reacted with water in a reverse Deacon process to form hydrogen chloride and oxygen, the hydrogen chloride obtained preferably being provided as the hydrochloric acid in process step b).

In this way, it can advantageously be achieved that the chlorine gas does not have to be disposed of, transported or stored in a complex manner. What can also be achieved in this way is that the consumption of hydrochloric acid in the overall process is reduced. The use as hydrochloric acid is particularly preferred when the aqueous hydrogen chloride is obtained in the reverse Deacon process.

Alternatively or additionally, it can preferably be provided that the hydrogen chloride obtained is used as hydrogen chloride in process step c) and / or d). This use is particularly preferred when essentially anhydrous hydrogen chloride gas is obtained in the reverse Deacon process. In a preferred embodiment, it can be provided that the reverse Deacon process in an aqueous environment with a catalyst, preferably a transition metal catalyst, in particular nickel or cobalt catalyst, at a temperature in a range from greater than or equal to 45 ° C to less than or equal to 70 ° C , for example at 60 ° C, in the presence of a hydrochloric acid-binding material, for example magnesium oxide, is carried out, for example magnesium chloride and oxygen being formed. In a subsequent step, the magnesium chloride formed is preferably decomposed with water to form hydrogen chloride and magnesium oxide at a temperature in a range from greater than or equal to 450.degree. C. to less than or equal to 550.degree.

As an alternative to magnesium chloride, separation of the dissolved hydrogen chloride obtained by means of known liquid-liquid extraction systems for hydrogen chloride at low temperatures is an energetically advantageous embodiment.

In a further embodiment, it can preferably be provided that the reverse Deacon process is catalyzed in an aqueous environment with solar radiation.

In an alternative preferred embodiment, it can be provided that the reverse Deacon process is carried out in a non-aqueous environment at a temperature in a range from greater than or equal to 550 ° C. to less than or equal to 650 ° C., for example 600 ° C., with off Chlorine and water Hydrogen chloride and oxygen are formed, the hydrogen chloride being present as hydrochloric acid and a catalyst preferably optimizing the conversion reaction

It can preferably be provided that in process step j) the titanium trichloride or the titanium dichloride is introduced into a molten salt and into the molten salt is disproportionated, the molten salt being a melt of magnesium chloride, calcium chloride, potassium chloride, sodium chloride or mixtures thereof.

In this way it can advantageously be achieved that the titanium trichloride or the titanium dichloride is disproportionated in a targeted manner. In addition, it can be achieved that the titanium tetrachloride can be separated off particularly easily and quickly, since it has only a low solubility in the molten salt and outgasses quickly. Thus, the reaction equilibrium can advantageously be shifted further to the product side and the location of the deposition can be better controlled.

It can preferably be provided that a metal element, preferably a metal element with a titanium surface, in particular a titanium element, protrudes into the molten salt. It can advantageously be provided that the molten salt is heated via the metal element. In addition, it can be provided that the titanium is deposited on the heated titanium element. The titanium element can grow accordingly and be removed as a semi-finished product for further processing.

In a preferred embodiment, it can be provided that the metal element is movably mounted in the reactor and this enables, among other things, the continuous removal of the titanium.

To prevent oxidation, the disproportionation steps should preferably take place under a sufficient vacuum or, in a particularly preferred embodiment, in an inert or reactive protective gas atmosphere. Argon and hydrogen are particularly suitable for this purpose, and in the case of hydrogen, depending on the application, the retention of titanium hydride as a product may be explicitly desired. For example, the goal of energy storage, transport or preservation of titanium powder. It can preferably be provided that heat is exchanged through heat exchangers during the process steps. As a result, it can advantageously be achieved that the total energy required for the entire process can be reduced. In particular, it can thereby be achieved in a particularly advantageous manner that the energy to be supplied externally for the individual steps can be kept particularly low. This means that the area required for heliostats and the investment required for solar bundling can be kept small.

It can preferably be provided that in process step b) heat is released and the heat is dissipated via a heat exchanger. It can preferably be provided that in process step c) heat is released and the heat is dissipated via a heat exchanger. It can preferably be provided that in method step e) heat is absorbed and the heat is supplied via a heat exchanger. It can preferably be provided that in method step i) heat is absorbed and the heat is supplied via a heat exchanger. It can preferably be provided that in method step j) heat is absorbed and the heat is supplied via a heat exchanger.

The thermal energy released by the exothermic reactions and during cooling is preferably used to heat up and drive the endothermic reactions to the appropriate temperature level.

The waste heat obtained in the thermochemical cycle process and necessarily dissipated according to the Camot principle can be dissipated to the environment with appropriate air, geothermal or water heat exchangers. Preferably, inexpensive thermal masses such as soil regenerated by air cooling at night are also suitable. It can preferably be provided that thermal energy for the process steps is provided by solar radiation, preferably through flat or vacuum collectors, a parabolic trough power plant, a solar dish receiver and / or through a solar tower heat exchanger, the thermal energy in particular for process steps d), e), h ), i) and j) is provided.

As a result, it can advantageously be achieved that the process is particularly environmentally friendly and no further expensive secondary energy sources are necessary.

It can preferably be provided that the alkali metal chloride obtained in process step e) is used as the alkali metal chloride in process step c).

As a result, it can advantageously be achieved that less alkali metal chloride is consumed per quantity of titanium produced.

The combination of the process steps according to the invention thus makes it possible for the reactants used and the substances involved to be recycled to a very large extent, so that ultimately the central reaction of titanium dioxide with the supply of heat to elemental metal and oxygen can be achieved practically completely as a net reaction.

It can preferably be provided that the process is carried out as a continuous process. This enables the process to be operated particularly efficiently because the heat generated can be used particularly well.

The invention also proposes a device for the thermochemical production of titanium by the method described above, having at least one first reactor, preferably an acid-resistant stirred tank reactor, for the digestion of a Starting material comprising titanium dioxide with mineral acid, the first reactor having an inlet for the starting material, an inlet for the mineral acid and an outlet for a solution comprising dissolved titanium (IV), the first reactor preferably having a heat exchanger, a second reactor, preferably one acid-resistant precipitation reactor for precipitating an alkali metal titanium (IV) hexachloride, the second reactor having an inlet for the solution containing dissolved titanium (IV), an inlet for hydrochloric acid or hydrogen chloride, an inlet for alkali metal chloride and an outlet for precipitated alkali metal titanium (IV) tetrachloride , the second reactor being designed to enable the separation of precipitated alkali metal titanium (IV) hexachloride and reaction solution, the second reactor preferably having a heat exchanger, optionally a third reactor, preferably a tube dryer or belt dryer, for drying alkali metal titanium (IV) hexachloride, the third reactor having an inlet for alkali metal titanium (IV) hexachloride, an inlet for hydrogen chloride and an outlet for dried alkali metal titanium (IV) hexachloride, the third reactor preferably having a heat exchanger, a fourth reactor, preferably a tube dryer or belt dryer, for heating the alkali metal titanium (IV) hexachloride, the fourth reactor having an inlet for alkali metal titanium (IV) hexachloride, an outlet for alkali metal chloride and an outlet for gaseous titanium tetrachloride, the fourth reactor preferably having a heat exchanger, the fourth reactor preferably is designed in such a way that it enables a reaction under a protective atmosphere, a fifth reactor, for reducing the gaseous titanium tetrachloride, with a reducing agent to titanium trichloride, the fifth reactor having an inlet for titanium tetrachloride, an inlet for reducing agent, an outlet for oxidized s has reducing agent and a drain for titanium trichloride, a device for recycling and providing the reducing agent having an inlet for oxidized reducing agent and an outlet for recycled reducing agent, optionally a sixth reactor for disproportionation of the titanium trichloride to titanium tetrachloride and titanium dichloride, the sixth reactor having an inlet for titanium trichloride, an outlet for titanium tetrachloride and an outlet for titanium dichloride, a seventh reactor for the disproportionation of titanium trichloride or titanium dichloride to titanium and titanium tetrachloride, the seventh reactor having an inlet for titanium trichloride or titanium dichloride and an outlet for titanium tetrachloride, the seventh reactor being designed to separate titanium and the other reactants to enable, and a device for recycling the titanium tetrachloride formed in the seventh and optionally sixth reactor to the fifth reactor, the third, fourth, fifth, sixth and / or sieves nte reactor is preferably gas-tight to the environment.

In the context of the present invention, an inlet is to be understood as a device which enables the addition of the corresponding substance. For example, an inlet can be understood to mean a nozzle, a pipe, a hatch or a simple opening. In the context of the present invention, a process is to be understood as meaning a device which enables the corresponding substance to be removed.

It can be provided that an inlet or outlet for one substance can also serve as an inlet and / or outlet for another substance. Accordingly, it can be provided, for example, that the inlet for the starting material of the first reactor is an opening on an upper side of the reactor and the same opening also serves as an inlet for the mineral acid. It can preferably be provided that at least one of the fifth, sixth and seventh reactors, particularly preferably the fifth reactor, can be operated with solar heat, in particular via a UV-permeable window in a wall of the reactor.

It can preferably be provided that the first reactor has several divided acid-proof reactors, e.g. 8 acid-proof containers each with agitator transport and conveying device as well as heat exchangers, whereby the titanium ore is passed in countercurrent in steps past the mineral acid. A particularly efficient resolution is achieved in this way. The material of the reactor is preferably acid-proof coated steel or acid-proof plastic.

A particularly preferred embodiment of the second reactor contains a stirring and circulation system for complete mixing and salting of the continuously supplied alkali salt to form hexachlorotitanate.

Furthermore, it can be provided that, in a preferred embodiment, the second reactor has a continuous removal device, for example a centrifuge with an automatic conveying device for separating and pre-drying the hexachlorotitanate crystals.

Due to the increased hydrogen chloride pressure above the solution for the precipitation reaction, it can be provided that the second reactor has a pressure-tight, gas-tight and / or acid-resistant envelope.

In a further energetically preferred variant, the solution in the inflow can be saturated with hydrogen chloride in countercurrent with the solution in the outflow from which the titanium chloride was previously precipitated in the second reactor. The hydrogen chloride gas can gradually outgas in the downstream channel and turn into the Loosen the inflow channel and fiir there for an increasing hydrogen chloride content. A simultaneous heat exchange of the saturation reaction of the inflow to the second reactor and outgassing of the outflow is a very preferred embodiment. For this purpose, the inflow and outflow of the second reactor can be designed in several sections, each with an integrated gas exchange through a common gas volume on the surface and local heat exchange of the respective solutions.

As a further preferred embodiment, depending on the starting material, in connection with the supply of the titanium-containing solution from the first reactor to the second reactor, any dissolved iron salts or further foreign salts are separated off beforehand. Embodiments can preferably have a liquid-liquid extractor with mixer and separation chambers, furthermore a crystallization and separation device, or furthermore a device for separation by means of an ion exchanger integrated in the inlet of the second reactor.

Likewise, a preferred configuration of the feed to the second reactor can have a device for oxidation or reduction. In the case of oxidation it can be provided that the device has a pipe system with outlet openings below the surface of the solution, through which oxygen or chlorine gas can be blown.

Here, a very preferred embodiment with regard to an oxidation of a pipe connection from the decomposition reaction chamber makes use of reaction h) for recycling chlorine or oxygen gas.

In a preferred embodiment, the fifth reactor for the reduction of titanium tetrachloride with hydrogen has a pressure-tight housing which is at least partially made of UV-permeable glass, which is used to optically couple the catalytically active UV radiation. In a very preferred embodiment, in particular the inner surfaces of reactors six and seven, and any heat exchangers 444 integrated with them, are lined with a material that does not contain oxygen.

The invention is explained further below with reference to the figures. The figures show possible embodiments of the invention. In principle, however, combinations or modifications of the configurations are also possible within the scope of the invention.

Show it

1 schematically shows the method steps of the method according to the invention;

2 schematically shows the method according to the invention and the device according to a first exemplary embodiment;

3 schematically shows the method according to the invention and the device according to a second exemplary embodiment;

FIGS. 4a and 4b schematically show different configurations of method step j);

5 schematically shows various devices for providing thermal energy with solar thermal energy; and

6 schematically shows the main reactions of the process, chlorine gas from process step h) being reacted with water in a reverse Deacon process to form hydrogen chloride and oxygen.

1 shows schematically the method steps of the method according to the invention. The process for the thermochemical production of titanium 100, initially as Method step of providing gaseous titanium tetrachloride 110. The provision of gaseous titanium tetrachloride 110 initially comprises the provision of a starting material comprising titanium dioxide 111. This is followed by dissolving the titanium dioxide 112 in hydrochloric acid at a temperature in a range from greater than or equal to 30 ° C. to less than or equal to 120 ° C. to form an aqueous solution having dissolved hydrogen chloride and dissolved titanium tetrachloride. This is followed by precipitation of an alkali metal titanium (IV) hexachloride 113 from the aqueous solution with an alkali metal chloride with the addition of hydrochloric acid at a temperature in a range from greater than or equal to -15 ° C. to less than or equal to 30 ° C., the alkali metal being selected from the group consisting of lithium, sodium and potassium. This is followed by drying the alkali metal titanium (IV) hexachloride 114 with hydrogen chloride at a temperature in a range from greater than or equal to 50.degree. C. to less than or equal to 250.degree. The dried alkali metal titanium (IV) hexachloride (115) is then heated at a temperature in a range from greater than or equal to 500 ° C. to less than or equal to 600 ° C. with the formation of solid alkali metal chloride and gaseous titanium tetrachloride.

After the provision of gaseous titanium tetrachloride 110, the gaseous titanium tetrachloride is reduced 120 to titanium trichloride. The reduction 120 initially comprises providing a reducing agent 121. Subsequently, the gaseous titanium tetrachloride is reduced 122 with the reducing agent, releasing chlorine to titanium trichloride at a temperature in a range of greater than or equal to 20 ° C. to less than or equal to 440 ° C., the reducing agent being oxidized with the absorption of chlorine. The oxidized reducing agent obtained in this process step is recycled 123 by reduction with the formation of chlorine gas. The recycled reducing agent is then provided 123 as a reducing agent in the previous method step.

After the reduction to titanium trichloride 120, a disproportionation of the titanium trichloride to titanium and titanium tetrachloride 130 follows, comprising the process steps. Optional is initially the titanium trichloride to titanium tetrachloride and titanium dichloride disproportionate 131 at a temperature in a range from greater than or equal to 400 ° C to less than or equal to 600 ° C. The titanium trichloride or titanium dichloride is then disproportionated 132 to titanium and titanium tetrachloride at a temperature in a range from greater than or equal to 800 ° C to less than or equal to 1900 ° C. The resulting titanium tetrachloride is provided 133 as titanium tetrachloride for the reduction of the gaseous titanium tetrachloride with the reducing agent 122.

Then the obtained titanium is separated 140.

Fig. 2 shows schematically the method according to the invention and the device according to a first embodiment. Fig. 3 shows schematically the method according to the invention and the device according to a second embodiment. The device 500 in FIGS. 2 and 3 each has a first reactor 510. The first reactor 510 is, for example, an acid-resistant stirred tank reactor and has an inlet for the starting material 511, an inlet for the mineral acid 512 and an outlet for a solution containing dissolved titanium (IV) 513. Thus, in the first reactor 510, a starting material comprising titanium dioxide is provided 111 and digested 112 with mineral acid, a solution comprising dissolved titanium (IV) being formed. The device 500 furthermore has a second reactor 520. This is, for example, an acid-resistant precipitation reactor. The second reactor 520 has an inlet for the solution containing dissolved titanium (IV) 521, an inlet for hydrochloric acid 522, an inlet for alkali metal chloride 523 and an outlet for precipitated alkali metal titanium (IV) tetrachloride 524. The second reactor is designed to enable the separation of precipitated alkali metal titanium (IV) hexachloride and reaction solution. The alkali metal titanium (IV) hexachloride is correspondingly precipitated 113 in the second reactor 520. The device 500 also has a third reactor 530, for example a tube dryer or belt dryer. The third reactor 530 has an inlet for alkali metal titanium (IV) hexachloride 531, an inlet for hydrogen chloride 533 and a drain for dried alkali metal titanium (IV) hexachloride 533. The alkali metal titanium (rV) tetrachloride 114 is dried in the third reactor 530. Furthermore, the device 500 has a fourth reactor 540, which can likewise be, for example, a tube dryer or belt dryer. The fourth reactor 540 has an inlet for dried

Alkali metal titanium (IV) hexachloride 541, a drain for alkali metal chloride 542 and a drain for gaseous titanium tetrachloride 543. In the fourth reactor 540, the dried alkali metal titanium (IV) hexachloride is heated 115 with the formation of solid alkali metal chloride and gaseous titanium tetrachloride. The device 500 also has a fifth reactor 550. The fifth reactor 550 has an inlet for

Titanium tetrachloride 551, an inlet for a reducing agent 552, an outlet for oxidized reducing agent 553 and an outlet for titanium trichloride. In the fifth reactor 550, the gaseous titanium tetrachloride is reduced 112 with the reducing agent.

The device 500 also has a device for recycling and providing the reducing agent 555. The device for recycling reducing agent has an inlet for oxidized reducing agent 556 and an outlet for recycled reducing agent 557. In the embodiment according to FIG. 2, the device for recycling hydrogen gas is designed as a reducing agent. In the embodiment according to FIG. 3, the device for recycling vanadium (II) chloride is designed. The device 500 according to FIG. 2 also has an optional sixth reactor 560. The sixth reactor 560 has an inlet for titanium trichloride 561, an outlet for titanium tetrachloride 562 and an outlet for titanium dichloride 563. In the sixth reactor 560, the disproportionation of the titanium trichloride to titanium tetrachloride and titanium dichloride 131 optionally takes place. The device 500 according to FIGS. 2 and 3 then has a seventh reactor 570 in each case. The seventh reactor 570 has an inlet for titanium trichloride 571 in FIG. 3 or an inlet for titanium dichloride 571 in FIG. 2, as well as an outlet for titanium tetrachloride 572. Furthermore, the device 500 has a device for recycling 573 of the 570 in the seventh and optionally sixth 560 reactor formed titanium tetrachloride to the fifth reactor 550. The seventh reactor is designed to enable separation of titanium and the other reactants. FIGS. 4a and 4b schematically show different configurations of method step j). 4a shows an embodiment of method step j), the disproportionation of titanium trichloride or titanium dichloride to titanium and titanium tetrachloride 132, for example of titanium dichloride in a molten salt 300 of magnesium chloride. The titanium dichloride dissolves in the molten salt 300. The disproportionation 132 takes place as a result of the supply of heat via the reaction vessel. Titanium powder 301 precipitates and titanium tetrachloride is produced, which is further made available to the method 133. Titanium powder 300 can then be separated 140 from the molten salt using known methods. 4b shows an embodiment of method step j), the disproportionation of titanium trichloride or titanium dichloride to titanium and titanium tetrachloride 132, for example of titanium dichloride in a molten salt 300 of magnesium chloride. The titanium dichloride dissolves in the molten salt 300. The disproportionation 132 takes place by supplying heat via a movable titanium element 302. In the process, titanium is deposited on the titanium element 302. The titanium is separated 140 from the melt by pulling out the titanium element 302. FIG. 5 schematically shows various devices for providing thermal energy with solar thermal energy. In large systems in particular, mirror surfaces can be produced inexpensively. Suitable materials are, for example, glass mirrors, highly reflective plastic films coated with metal or aluminum, and protected, polished aluminum sheets. Each of the collector shapes has technical and economic advantages in different temperature ranges and can be selected accordingly. If necessary, the heat transfer between the reactions and the heat exchangers of the cycle process can be carried out with passively or actively circulating heat carriers, such as water at low temperatures or thermal oils, with gas flow, with salt or Metal melts or bypassed ceramic elements are implemented at high process temperatures. For the temperature range from 50 ° C to 180 ° C, a flat-plate collector 400 with absorber 411, circulation line 412, housing with possibly thermal insulation 415 and glass or plastic windows is particularly suitable. For temperatures in a range from 120 ° C to 600 ° C, a parabolic interior system 420 with receiver or absorber with heat transfer medium 412, tracking and foundation 422 and parabolic mirror surface 423 is suitable. For temperatures in a range from 400 ° C to 2000 ° C are suitable Solar dish receiver 430 with absorber / reactor 431 and parabolic mirror 432 or solar tower heat exchanger with trackable mirror surface 441, with trackable axes and support structure 442,

High temperature absorber with heat exchanger or reactor 443 and tower with supply lines or heat transfer medium 444

Necessary systems for heat dissipation (cooling tower, air or geothermal heat exchanger) are not shown.

6 shows schematically the main reactions of the process, chlorine gas from process step h) being reacted with water in a reverse Deacon process to form hydrogen chloride and oxygen. The provision of gaseous titanium tetrachloride comprises the reaction of titanium dioxide with hydrochloric acid in aqueous solution to form titanium tetrachloride via alkali metal titanium hexachloride. During the reduction of the gaseous titanium tetrachloride with the reducing agent 122, for example with vanadium (II) chloride, the titanium tetrachloride reacts to form titanium trichloride and vanadium (III) chloride. This is optionally followed by the disproportionation of the titanium trichloride to titanium tetrachloride and titanium dichloride 131 and the disproportionation of the titanium trichloride or titanium dichloride to titanium and titanium tetrachloride 132. The titanium tetrachloride produced in each case is provided again as titanium tetrachloride 133. After the reduction 122, the oxidized reducing agent is removed, for example, as vanadium (III) chloride and recycled 123 by heating while releasing chlorine gas. The recycled reducing agent is thus provided again 124 as reducing agent.

The chlorine gas reacts in a reverse Deacon process 200 to form hydrogen chloride or hydrochloric acid and oxygen. The hydrogen chloride or hydrochloric acid is again provided 201 for the process.

7 shows an approximate estimate of the heat requirement without heat recovery on the basis of known thermodynamic properties of the selected reactants.

Reference number:

100 Process for the thermochemical production of titanium

110 Provision of gaseous titanium tetrachloride

111 Providing a starting material comprising titanium dioxide

112 Digestion of the starting material

113 cases of an alkali metal titanium (IV) hexachloride

114 Drying the alkali metal titanium (IV) hexachloride

115 Heat the dried alkali metal titanium (IV) hexachloride

120 Reduction of the gaseous titanium tetrachloride to titanium trichloride

121 Provision of a reducing agent

122 Reduction of the gaseous titanium tetrachloride with the reducing agent

123 Recycle the oxidized reducing agent

124 Provision of the recycled reducing agent as reducing agent

130 Disproportionation of titanium trichloride to titanium and titanium tetrachloride

131 Disproportionation of titanium trichloride to titanium tetrachloride and titanium dichloride 132 Disproportionate titanium trichloride or titanium dichloride to titanium and titanium tetrachloride

133 Providing the titanium tetrachloride obtained in process step as

Titanium tetrachloride

140 Separation of the titanium obtained

200 reverse Deacon process with release of oxygen

201 Providing the hydrochloric acid

300 molten salt

301 Titanium precipitation

302 metal element, titanium element

400 flat plate collector

411 absorber

412 circulation line

415 housing

420 Parabolic internal system, parabolic trough power plant

422 Tracking and Foundation

423 parabolic mirror surface

430 Solar Dish Receiver

431 absorber / reactor

432 parabolic mirror

440 solar tower heat exchanger

441 trackable mirror surface

442 trackable axes and beam structure

443 high temperature absorber with heat exchanger or reactor

444 Tower with supply lines or heat transfer medium

500 Device for the thermochemical production of titanium

510 first reactor

511 Feed for starting material 512 Inlet for mineral acid

513 Process for solution containing dissolved titanium (IV)

520 second reactor

521 Feed for solution containing dissolved titanium (IV) 522 Feed for hydrochloric acid

523 Inlet for alkali metal chloride

524 Drain for precipitated alkali metal titanium (IV) hexachloride

530 third reactor

531 Feed for alkali metal titanium (IV) hexachloride 532 Feed for hydrogen chloride

533 Drain for dried alkali metal titanium (IV) hexachloride

540 fourth reactor

541 Feed for dried alkali metal titanium (IV) hexachloride

542 Drain for alkali metal chloride 543 Drain for gaseous titanium tetrachloride

550 fifth reactor

551 Inlet for titanium tetrachloride

552 Inlet for reducing agent

553 Drain for oxidized reducing agent 554 Drain for titanium trichloride

555 Device for recycling and supplying reducing agent

556 Inlet for oxidized reducing agent

557 outlet for recycled reducing agent 560 sixth reactor 561 inlet for titanium trichloride

562 Drain for titanium tetrachloride

563 Drain for titanium dichloride 570 Seventh reactor Inlet for titanium trichloride or titanium dichloride Outlet for titanium tetrachloride Device for recycling titanium tetrachloride

Claims

1. A process for the thermochemical production of titanium (100), comprising at least the process steps:

Providing gaseous titanium tetrachloride (110) comprising the process steps: a) Providing a starting material comprising titanium dioxide (111), in particular providing titanium dioxide and / or ilmenite, b) digesting the starting material (112) in mineral acid, preferably in hydrochloric acid, at a temperature in a range from greater than or equal to 25 ° C. to less than or equal to 135 ° C. with the formation of a solution, in particular an aqueous solution, comprising dissolved titanium (IV), c) precipitating an alkali metal titanium (IV) hexachloride (113) from the solution with a Alkali metal chloride with the supply of hydrochloric acid or hydrogen chloride at a temperature in a range from greater than or equal to -15 ° C. to less than or equal to 30 ° C., the alkali metal being selected from the group consisting of lithium, sodium and potassium, d) optionally drying the Alkali metal titanium (IV) hexachloride (114) with hydrogen chloride at a temperature in the range of g greater than or equal to 30 ° C to less than or equal to 250 ° C, e) heating the alkali metal titanium (IV) hexachloride (115) at a temperature in a range from greater than or equal to 340 ° C to less than or equal to 700 ° C with the formation of solid Alkali metal chloride and gaseous titanium tetrachloride;

Reduction of the gaseous titanium tetrachloride to titanium trichloride (120) comprising the process steps: f) providing a reducing agent (121), preferably selected from the group consisting of hydrogen gas and transition metal chloride, the transition metal chloride being selected from the group consisting of vanadium (II) chloride, iron (II) chloride, chromium (II) chloride, cobalt ( II) chloride, nickel (II) chloride, copper (I) chloride, antimony (II) chloride, tin (II) chloride, and

Mixtures thereof, the transition metal chloride being preferably vanadium (II) chloride, g) reduction of the gaseous titanium tetrachloride with the reducing agent (122) with the release of chlorine to titanium trichloride at a temperature in a range from greater than or equal to 20 ° C to less than or equal to 440 ° C, the reducing agent being oxidized with the absorption of chlorine, h) recycling of the oxidized reducing agent (123) obtained in method step g) by reduction within a predominantly thermal cycle with the formation of chlorine gas and / or oxygen and providing the recycled reducing agent as reducing agent (124) in method step f);

Disproportionation of the titanium trichloride to titanium and titanium tetrachloride (130) comprising the process steps: i) optionally disproportionation of the titanium trichloride to titanium tetrachloride and titanium dichloride (131) at a temperature in a range from greater than or equal to 400 ° C to less than or equal to 800 ° C, j) Disproportionation of the titanium trichloride or the titanium dichloride to titanium and titanium tetrachloride (132) at a temperature in a range from greater than or equal to 580 ° C to less than or equal to 1900 ° C, k) providing the titanium tetrachloride obtained in process step j) and optionally i) as titanium tetrachloride (133) in process step g); and separating the obtained titanium (140).

2. The method according to claim 1, characterized in that the reducing agent from process step f) is hydrogen gas and the reduction from process step g) is carried out at a temperature in a range from greater than or equal to 20 ° C to less than or equal to 440 ° C, preferably from greater than or equal to 130.degree. C. to less than or equal to 240.degree. C., for example at 180.degree. C., the hydrogen gas being oxidized to hydrogen chloride with the uptake of chlorine, in process step h) the hydrogen chloride with vanadium (II) chloride to form Vanadium (III) chloride is reduced to hydrogen gas at a temperature in a range from greater than or equal to 60 ° C. to less than or equal to 390 ° C., preferably from greater than or equal to 160 ° C. to less than or equal to 280 ° C., for example 200 ° C. , wherein the hydrogen gas is used again as a reducing agent in process step f), and wherein the vanadium (III) chloride is formed with the formation of chlorine gas by heating at a temper atur in a range from greater than or equal to 480 ° C. to less than or equal to 700 ° C., preferably from greater than or equal to 560 ° C. to less than or equal to 580 ° C., for example. 570 ° C, is recycled to vanadium (II) chloride.

3. The method according to claim 2, characterized in that the reduction in process step g) is catalyzed, particularly preferably by exposure to UV-containing radiation or a catalyst, the UV-containing radiation preferably being obtained from sunlight.

4. The method according to claim 1, characterized in that the reducing agent from process step f) is vanadium (II) chloride and the reduction from process step g) is at a temperature in a range from greater than or equal to 80 ° C to less than or equal to 420 ° C is carried out, preferably from greater than or equal to 240 ° C to less than or equal to 360 ° C, for example at 320 ° C, wherein the vanadium (II) chloride is oxidized to vanadium (III) chloride with the absorption of chlorine, wherein in process step h) the vanadium (III) chloride is reduced to vanadium (II) chloride with the formation of chlorine gas at a temperature in a range from greater than or equal to 470 ° C. to less than or equal to 800 ° C., preferably from greater than or equal to 590 ° C. to less than or equal to 660 ° C., for example 620 ° C., the vanadium (II) chloride being preferred as the reducing agent in process step f ) provided.

5. The method according to any one of the preceding claims, characterized in that the chlorine gas from process step h) is reacted with water in a reverse Deacon process (200) to form hydrogen chloride and oxygen, the hydrogen chloride obtained preferably being provided as the hydrochloric acid in process step b) becomes (201).

6. The method according to any one of the preceding claims, characterized in that in method step j) the titanium trichloride or the titanium dichloride is introduced into a molten salt (300) and is disproportionated in the molten salt (300), the molten salt (300) being a melt of magnesium chloride , Calcium chloride, potassium chloride, sodium chloride, or mixtures thereof.

7. The method according to any one of the preceding claims, characterized in that heat is exchanged through heat exchangers during the process steps.

8. The method according to any one of the preceding claims, characterized in that thermal energy for the process steps is provided by solar radiation, preferably by flat or vacuum collectors (400), a Paraboirinnenkraftwerk (420), a solar dish receiver (430) and / or by a Solar tower heat exchanger (440), the thermal energy being provided in particular for process steps d), e), h), i) and j).

9. Device for the thermochemical production of titanium (500) according to the method according to one of the preceding claims, comprising at least one first reactor (510), preferably acid-resistant stirred tank reactor, for digesting a starting material comprising titanium dioxide with mineral acid, the first reactor (510) having a Has an inlet for the starting material (511), an inlet for the mineral acid (512) and an outlet for a solution containing dissolved titanium (IV) (513), the first reactor (510) preferably having a heat exchanger, a second reactor (520 ), preferably an acid-resistant precipitation reactor, for precipitating an alkali metal titanium (IV) hexachloride, the second reactor (520) having an inlet for the solution containing dissolved titanium (IV) (521), an inlet for hydrochloric acid or hydrogen chloride (522), an inlet for alkali metal chloride (523) and a drain for precipitated alkali metal titanium (IV) tetrachloride (524), the two The first reactor (520) is designed to enable the separation of precipitated alkali metal titanium (IV) hexachloride and reaction solution, the second reactor preferably having a heat exchanger, optionally a third reactor (530), preferably a tube dryer or belt dryer, for drying alkali metal titanium (IV ) hexachloride, the third reactor (530) having an inlet for alkali metal titanium (IV) hexachloride (531), an inlet for hydrogen chloride (532) and an outlet for dried alkali metal titanium (IV) hexachloride (533), the third reactor preferably having one Has heat exchanger, a fourth reactor (540), preferably tubular dryer or belt dryer, for heating the alkali metal titanium (rV) hexachloride, the fourth reactor (540) having an inlet for alkali metal titanium (IV) hexachloride (541), an outlet for alkali metal chloride (542) and an outlet for gaseous titanium tetrachloride (543), the fourth reactor preferably having a heat exchanger t, the fourth reactor preferably being designed in such a way that it enables a reaction under a protective atmosphere, a fifth reactor (550) for reducing the gaseous titanium tetrachloride with a reducing agent to titanium trichloride, the fifth reactor (550) having an inlet for titanium tetrachloride (551), an inlet for reducing agent (552), an outlet for oxidized reducing agent (553) and having an outlet for titanium trichloride (554), a device for recycling and providing the reducing agent (555) having an inlet for oxidized reducing agent (556) and an outlet for recycled reducing agent (557), optionally a sixth reactor (560) for disproportionation of the titanium trichloride to titanium tetrachloride and titanium dichloride, the sixth reactor (560) having an inlet for titanium trichloride (561), an outlet for titanium tetrachloride (562) and an outlet for titanium dichloride (563), a seventh reactor (570) for the disproportionation of the titanium trichloride or the titanium dichloride to titanium and titanium tetrachloride, the seventh reactor (570) ei NEN inlet for titanium trichloride or titanium dichloride (571) and an outlet for titanium tetrachloride (572), the seventh reactor being designed to allow separation of titanium and the other reactants, and a device for recycling (573) the seventh and optionally sixth Titanium tetrachloride formed in the reactor to the fifth reactor, the third, fourth, fifth, sixth and / or seventh reactor preferably being gas-tight to the environment.

10. The device according to claim 9, characterized in that at least one of the fifth, sixth and seventh reactor, particularly preferably the fifth reactor, can be operated with solar heat, in particular via a UV-permeable window in a wall of the reactor.