WO2019057431A1

WO2019057431A1 - Co2-free electrochemical production of metals, and alloys consisting thereof

Info

Publication number: WO2019057431A1
Application number: PCT/EP2018/072640
Authority: WO
Inventors: Günter Schmid; Bernhard Schmid
Original assignee: Siemens Aktiengesellschaft
Priority date: 2017-09-19
Filing date: 2018-08-22
Publication date: 2019-03-28
Also published as: DE102017216564A1

Abstract

The present invention relates to a method for producing a metal M and/or a mixture and/or an alloy thereof in a reduction cell comprising at least one anode and at least one cathode, wherein a compound of the metal M and optionally at least one other compound of an alloy component is dissolved in an aqueous solution and the metal M and/or a mixture and/or an alloy thereof is electrochemically deposited on the at least one cathode.

Description

description

C0 ₂ ~ free electrochemical production of metals and alloys thereof

The present invention relates to a method for the manufacture ^¬ lung of a metal M and / or a mixture and / or alloy thereof in an electrolytic cell comprising at least one anode and at least one cathode, wherein a compound of the metal M, and optionally at least one further compound ei ^¬ nes alloying ingredient is converted into an aqueous solution and the metal M and / or a mixture and / or alloy coins ^¬ tion of which is electrochemically deposited on the at least one cathode.

State of the art

For thousands of many metals, including iron, Ni disgust, cobalt, copper, and many metals, which are used for alloy steels ^¬ be prepared by smelting. For this purpose, usually sulfides are converted by roasting in oxides, which are then reduced with carbon or carbon monoxide to the metal. The carbon can also provide the necessary energy. The necessary high temperatures provide an additional energy requirement.

An exemplary general reaction equation is as follows:

Μ ^{η +} χΟ ( _{Χ * η)} / 2 + (x * n) / 4 C -> x M + (x * n) / 4 C0 ₂ , where n = 1, 2, 3, 4, 5, 6 the In this case, x is usually chosen in stoichiometric formulas such that x is itself and (x * n) / 2 is an integer. For the validity of the equation, x can be arbitrary. In this case, oxides with mixed oxidation states (general formula, for example, M ₃ O ₄ or M ₄ O ₃ ) are not excluded, since these are formally used as mixtures. formulate two oxides, for example, Fe ₃ 0 ₄ = Fe ₂ 0 ₃ + FeO, or similar compounds.

In particular, metals metallurgy as Fe, Ni, Co or Le ^¬ gierungsmetalle as W, Mn, V, Cr be industrially produced in blast furnace processes with fossil fuels such as coal. In this smelting significant amounts of CO _{2 are} emitted into the atmosphere. The iron or metal production by blast furnace processes is responsible for an average emission of 1.8 - 2 t CO ₂ per ton of crude steel (Brazil: 1.25 t C0 ₂ / t steel, US: 2.9 t C0 ₂ / t steel; Korea and Mexico: 1.6 t C0 ₂ / t steel, China and India: 3.1 to 3.8 t C0 ₂ / t steel). This adds up to 6.7% of global CO ₂ emissions. Global crude steel production in 2015 was 1,623 million tons per year. With a current crude steel price of 583 C / t (Jan. 2017), this means a market volume of 954 billion C.

In Germany, crude steel production was 46.3 Mt, which corresponds to 2.6%. 42.7 million tonnes of crude steel were produced in Germany in 2015 - correspondingly high are the CO ₂ emissions of this industry. 2014 were 51.4 emits Millio ^¬ nen tons, representing a share of 6.4 per cent of total emissions.

The most important method is the smelting of metallic oxides in the blast furnace with carbon from coke or carbon monoxide, e.g. for Fe or steel.

However, certain metals are produced electrochemically because of their normal potential. Examples are the alkali metals such as lithium, sodium, potassium or alkaline earth metals such as beryllium, calcium, magnesium, strontium or barium. The best known and most significant metal is aluminum. These metals, in turn, are used in part for the production of other metals, for example in the production of titanium according to the Kroll process:

TiCl ₄ + 2 Mg -> Ti + 2 MgCl ₂

Newer methods also use sodium. In principle, these metals can also be prepared electrochemically for the production of metal, but this process is more complex and therefore not included according to the invention.

Furthermore, methods are under discussion using hydrogen from renewable sources to reduce oxides in blast furnace like systems (see e.g.

http: // www. renewable energy . the first steelworks / 150/437/97758 /)

An example reaction is as follows:

Fe ₂ 0 ₃ + 6 H ₂ - * 2 Fe + 3 H ₂ 0

However, the reduction then still takes place in a furnace-like plant at high temperatures and thus with high energy expenditure.

Metals such as aluminum or else lithium can also be deposited from non-aqueous conductive solutions of their salts, for example halides. Examples include aluminum from ionic liquids or lithium

Pyridine or esters.

For other metals, however efficient method to de ^¬ ren production which kön- reduce the emission of C0 ₂ NEN missing. It is therefore an object of the invention to provide a method in which renewable energy from, for example, wind or solar can be used directly for electrochemical production of metals of metallurgy and / or alloying metals, so that the release of CO ₂ can be reduced. For example, the crude steel production should preferably be essentially C0 ₂ ~ free. In the course of the expansion of renewable energy in particular a direct production with "electrons" (electricity) is desired.

Summary of the invention

The inventors have developed an efficient electrolysis process in which anode current is used directly or indirectly to dissolve a compound of a metal M selected from Ti, V, Nb, Ta, Cr, Mo, W, Mn, Re, Fe, Co, Ni, Cu, Zn, Cd, Ga, In, Tl, Ge, Sn, Pb, As, Sb, Bi, Se or Te and / or a mixture and / or an alloy thereof, is then used to cathodically deposited in the electrolytic cell can be.

In particular, an economically attractive process compared to the previous blast furnace production can be provided. It is also possible to dispense with fossil sources and to use "electrons" as reducing agents from renewable energy such as wind and solar, In particular alloys can be deposited in this way with the method according to the invention In particular, according to certain embodiments, elaborate pretreatment of the ores of the metal M as in ^¬ example, the roasting are omitted.

The present invention relates to a process for the preparation of a metal M which is selected from Ti, V, Nb, Ta, Cr, Mo, W, Mn, Re, Fe, Co, Ni, Cu, Zn, Cd, Ga, In, T1, Ge, Sn, Pb, As, Sb, Bi, Se or Te and / or a mixture and / or alloy thereof, in an electrolytic cell comprising at least one anode and at least one cathode, wherein a compound of the metal M and optionally at least one further compound of an alloying constituent in an aqueous solution is transferred and the metal M and / or a mixture and / or alloy thereof is electrochemically deposited on the at least one cathode, said at least one anode comprising the compound of the metal M, preferably in the We ^¬ sentlichen from the at least is a compound of the metal M, and at least one compound of the metal M electrochemically an anode is at least transferred to an aqueous solution and / or wherein at least one Ver ^¬ bond of the metal M is transferred by means of a produced at the at least one anode connection in an aqueous solution and is introduced into the electrolysis cell.

Further aspects of the present invention can be found in the dependent claims and the detailed description.

Description of the figures

The accompanying drawings are intended to illustrate embodiments of the present invention and to provide further understanding thereof. In the context of the description, they serve to explain concepts and principles of the invention. Other embodiments and many of the stated advantages will become apparent with reference to the drawings. The elements of the drawings are not necessarily shown to scale to each other. Identical, functionally identical and identically acting elements, features and components are in the figures of the drawings, unless otherwise stated, each provided with the same reference numerals. FIG. 1 shows schematically the steps of a first embodiment of the method according to the invention. FIG. 2 shows in more detail the processes at a cathode K and an anode A of the first embodiment of the method according to the invention. FIG. 3 shows schematically the steps of a second embodiment of the method according to the invention.

FIGS. 4 and 5 show in more detail the processes at a cathode K and an anode A and at a release of a compound of the metal M in two different modes of operation of the second embodiment of the method according to the invention.

Detailed description of the invention

definitions

Used herein ^¬ tech niche and scientific terms have as otherwise defined the same meaning as commonly understood by a person skilled in the art of the invention commonly.

In the application, quantities are by weight. %, unless otherwise stated or obvious from the context.

The normal pressure is 101325 Pa = 1.01325 bar.

The present invention relates to a method for producing a metal M (which also includes semimetals as metals) selected from Ti, V, Nb, Ta, Cr, Mo, W, Mn, Re, Fe, Co , Ni, Cu, Zn, Cd, Ga, In, Tl, Ge, Sn, Pb, As, Sb, Bi, Se and Te and / or a mixture and / or alloy thereof in an electrolytic cell comprising at least one anode and at least one Cathode, wherein a compound of the metal M and optionally at least one further compound of an alloying component is converted into an aqueous solution and the metal M and / or a mixture and / or alloy thereof is electrochemically deposited on the at least one cathode, wherein the at least one anode comprises the compound of the metal M, preferably essentially consisting of the at least one compound of the metal M, and min ^¬ least one compound of metal M is electrochemically converted at the at least one anode in an aqueous solution and / or wherein at least one compound of metal M is transferred by means of a produced at the at least one anode connection in an aqueous solution and in the electrolysis cell is introduced.

The metal here is selected from Ti, V, Nb, Ta, Cr, Mo, W, Mn, Re, Fe, Co, Ni, Cu, Zn, Cd, Ga, In, Tl, Ge, Sn, Pb, As, Sb, Bi, Se and / or Te and / or a mixture and / or alloy thereof, wherein here no precious metals, ie Au, Ag, Hg, Pd, Pt, Rh, Ir, Ru and Os are included, wherein here in ^¬ particular the metals of the metallurgy, Fe, Ni, Co, Legie ^¬ approximately metals such as W, Mn, V, Cr, bearing metals such as Sb, Bi or corrosion protection coatings are such as Zn of economic importance ^¬ processing and correspondingly cost-efficiently by the inventive procedural ^¬ ren and can be easily made.

The metals which can be prepared from aqueous solution cathodically separate off - in particular, the above - result from the pH-dependence of the Nernst's equation ^x. The lower limit forms the side reaction of water ^¬ material forming the respective pH.

"RT a _H +

E _H2 = E _H ° ₂ + - ln ^ - 2 ² z ^■ F a _H2

Ε _Ηϊ electrode potential

E standard electrode potential (according to definition = 0 V at pH = 1) R Universal or molar gas constant, R = 8.31447

J-mol ^ -IC ¹ = 8, 31447 CV-mol ^ -IC ¹

T absolute temperature (= temperature in Kelvin) z number of transferred electrons (also equivalent number, here = 1)

F Faraday constant, F = 96485, 34 C-mol ^-1 = 96485, 34

JV ^ -mol ^-1 oc activity of the respective redox partner

By definition, ° ^ H ₂ ⁼ 1 · The concentration to be considered is used for the activity of the protons. After a ^¬ set of constants arises.

E _H2 = -59 mV ^■ pH

This results in the smallest for the metal deposition pass on theoretical potential of -826 mV, which is possibly lowered by overvoltages ^¬ gen on. However, these are highly dependent on the ERS ^¬ distinctive metal.

^ Metal ⁼ ^ metal +

z ^'F Red The activity ° c _Red of the deposited reduced metal by definition, is again 1. This means that concen- tere metal solutions are advantageous because they increase the Halbzellpo ^¬ tential E _Meta u, which conversely a deposition also preferred lower pH allowed.

Example: Ep _e = -0.04V. At a concentration of 1 mol / l of Fe ³⁺ ions, iron should not be able to be deposited at pH = 0 (0.5 ^molar H ₂ SO ₄ solution, assumed overvoltage hydrogen formation 0V). However, 0 V is only reached with a 7.6 molar solution of Fe ³⁺ (e ^{40 mV'3 / 59 mV} ). Indeed Already a buffering of the catholyte solution over pH = 1 or an overvoltage of 40 mV to form hydrogen from iron. This shows how easy that is

Set deposition conditions. The same applies to the other metals.

According to certain embodiments, the lower limit for the preparation of the metal M forms the water reduction in the strongly basic: 2 H ₂ O + 2e ^" = H ₂ + 20H ^" -0.8277 V. Since the metal deposition takes place cathodically, again no results

Upper limit. A metal M, whose potential is above the half-cell potential of 0V, divorces from ^¬ pH-independent. According to certain embodiments, the metal M is therefore selected from Ti, V, Nb, Ta, Cr, Mo, W, Mn, Fe, Co, Ni, Zn, Cd, Ga, In, Sn, Pb, Se and / or Te and / or a mixture and / or alloy thereof. In addition, according to certain embodiments, the metal is selected from metals which are not prone to passivation in the process according to the invention, in particular Mn, Fe, Co, Ni, Cd, Ga, In, Sn, Se and / or Te and / or a mixture and / or or alloy thereof. According to certain embodiments, the metal M is selected from Mn, Fe, Co and / or Ni and / or a mixture and / or alloy thereof. According to certain embodiments, the metal M is iron and / or an alloy thereof.

The alloys of the said metals are not particularly limited and may, for example, by additions of metals or metal cations, carbon, such as graphite, etc., are ^¬ ge gained using, for example with additives of metal cations in the present method directly ^¬ mixtures of metals can be recovered at the cathode. It is also not excluded that mixtures of compounds of the metals M, wherein more than one metal M is present, for example, 2, 3, 4, 5, 6, 7, 8, 9, 10 or more metals M, in erfindungsge ^¬ MAESSEN Procedures used to make multiple metal cations to convert into an aqueous solution, which can then be sequenti ^¬ ell or simultaneously, for example, sequentially deposited on one or ver ^¬ different sequentially introduced cathodes.

Preference is given to processes where the said metals can be deposited from aqueous electrolytes. In principle, many metals, as known from electroplating, can be deposited from aqueous solution. However, according to the invention additives such as brighteners can be dispensed with, since the

Process only aimed at the extraction of the metal M itself. A selection can for instance be made on the basis of Elektrodenpoten ^¬ tials, some example are given in Table 1 below.

Table 1: Exemplary electrode potentials compared to the standard hydrogen electrode under normal conditions (Excerpt from Wikipedia:

https: // en. wikipedia.org / wiki / Standard_electrode_potential_ (d ata page))

Oxidant Reductant E ° (V)

Ta ₂ 0 ₅ (s) + 10H ⁺ + 10e ^~ 2Ta (s) + 5H ₂ 0 -0.75

Cr ³⁺ + 3e ^- > Cr (s) -0.74

Zn ²⁺ + 2e ^- Zn (Hg) -0, 7628

Zn ²⁺ + 2e ^- Zn (s) -0, 7618

Ag ₂ S (s) + 2e ^~ 2Ag (s) + S ^{2 "} (aq) -0, 69

Au [Au (CN) ₂ + e ^~ Au (s) + 2 CN ^" -0, 60

Ta ³⁺ + 3e ^~ Ta (s) -0, 6

PbO (s) + H ₂ O + 2e ^~ Pb (s) + 20H ^~ -0.58

Ga ³⁺ + 3e ^~ ^ Ga (s) -0, 53

U ⁴⁺ + e ^ U ³⁺ -0, 52

Fe ²⁺ + 2e ^~ ^ Fe (s) -0.44

Cr ³ + + e ^~ ^ Cr ² + -0, 42

Cd ²⁺ + 2e ^~ ^ Cd (s) -0.40

Cu ₂ 0 (s) + H ₂ 0 + 2e ^ 2Cu (s) + 20ΒΓ-0, 360

PbS0 ₄ (s) + 2e ^~ Pb (s) + S0 ₄ ^{2 ~} -0, 3588

In ³⁺ + 3e ^~ ^ In (s) -0, 34

Au [AuCl ₄ + 3e ^~ Au (s) + 4C1 ^~ +0, 93

Au [AuBr ₂ ] ^~ + e ^~ ^ Au (s) + 2Br ^~ +0, 96

Au [AuCl ₂ ] ^~ + e ^~ ^ Au (s) + 2C1 ^~ +1.15

Pt ²⁺ + 2e ^~ Pt (s) +1.188

Au ³⁺ + 3e ^~ Au (s) +1, 52

Au ⁺ + e ^~ Au (s) +1.83

According to certain embodiments, the electrochemically deposited metals in the process according to the invention, for example in electric (regenerative) heated arc furnace, alloyed or further processed with the addition of carbon, etc.

The inventive method takes place in an electrolysis ^¬ cell, which is not particularly limited, and which at least one anode and at least one cathode comprises. The material of the electrolytic cell itself as well as the material of the cathode and anode can be adapted to the metal M and / or the compound of the metal M and / or one or more existing electrolytes. The anode, cathode and the electrolyte will now be described more exactly he ^¬. It should be noted that the fiction, ^¬ proper procedure takes place in aqueous solution, so it is not a fused-salt electrolysis. Besides, the compound of the metal M is not particularly limited insofar as it contains the metal M in a form which can be converted into an aqueous solution, that is, can release a metal cation. It may be present, for example, in the form of a salt or a covalent compound, for example in salt form. For example, the compound of the metal M may be present as ore of one or more metals, but also as roasted metal scrap or metal scrap itself, etc. Also mixed compounds of several metals M are possible. In this case, it is not excluded that a counterion of a metal cation is redeposited in the transfer into an aqueous solution in this, wherein the counterion but preferably also goes into solution. If necessary, this counterion can also continue to react. An example of this would be, for example, a chloride ion. In the compound of the metal M, for example, ores, foreign metals may be contained, which can be deposited either before or during the electrodeposition. Before deposition, according to certain embodiments, the compounds of the metal M can be converted into a solution, for example salt solutions, and the solutions

be recrystallized. For example, in the ions of the alkali metals and alkaline earth metals and / or lanthanides usually not disturbing because their normal potential is below that of the metal M and thus they are not deposited during the electrolysis or even the conductivity of the electrolyte and thus the energy efficiency of the electrolysis due to Reduction of ohmic losses can increase. This can also be extended for specific metals M, so that in the case of specific metals M further metals do not interfere. For example, in addition to alkali metals and alkaline earth metals such as magnesium, aluminum is not troublesome in iron production since its normal potential is below that of iron. Ins ^¬ particular alkaline earth metals can be separated as sparingly soluble sulfates already in the workup, so that, for example, a use of sulfates and / or sulfuric acid in the electrolysis, for example in the electrolyte, for example in the anolyte and / or catholyte, may be advantageous if Erd ^¬ alkali metals in the compound of the metal M are present. Depending on the compound of the metal M and, if appropriate, other constituents contained, the electrolyte can thus also be adapted in the process according to the invention, for example with regard to counterions (anions) in the preparation of the metal M.

According to certain embodiments, the compound of the metal M is hardly or not soluble in water, eg has a solubility in water at 25 ° C and normal pressure of less than 10 g / L, preferably less than 1 g / L, further be - preferably less than 0.1 g / L. As a result, the anode may comprise or consist of the compound of the metal M.

According to certain embodiments, the compound of the metal M includes an oxide and / or sulfide, or comprises an oxide and / or sulfide of the metal M. This may be a ^¬ polysubstituted by reaction in an aqueous solution are transferred, for example by reaction at the Anode or with min ^¬ least one anodically prepared compound. In addition, these are easily accessible and can be easily processed into an anode. The metals M are most of the usual ^¬ as before due to their normal potential in nature as oxides or sulphides. Before electrolysis, these example ^¬ example, in the second embodiment, for example by means of anodically prepared acids, such as acids whose anion can not be oxidized electrochemically at the anode, be solved. An example of this is the use of sulfuric acid with the particularly preferred element iron as metal M. An oxide of iron can be present in the oxidation state +2 or +3. eg oxidation state +3: Fe ₂ 0 ₃ + H ₂ S0 ₄ - * Fe ₂ (S0 ₄ ) ₃ + H ₂ 0

However, in these embodiments, the acid produced is not particularly limited, and it is also sufficient if proton or hydroxonium ions are prepared at an anode, which are used for producing an acid, for example, in a water electrolysis. H ₂ 0 - 2e ^" -> H 0 ₂ + 2 H ⁺

However, with suitable counterions an acid can also be "generated" directly at the anode and react with the compound of the metal M or led out of the electrolysis cell to carry out a solution of the compound of the metal M at a location outside the electrolytic cell and then Metal ^¬ cations lead to the electrolysis cell This also includes a concentration of an acid by, for example, this is concentrated higher by a water electrolysis. For example, as acids in addition to sulfuric acid and HF, KHF ₂ , CF ₃ -S0 ₂ -OH, etc. into consideration. In addition to sulfuric acid, it is thus also possible to use other acids for breaking down the compound of the metal M. In particular, fluoride ions usually form stable nega tive ^¬ charged complex ions with multivalent ions, for example, iron, aluminum, cobalt or titanium and are DA very suitable for the digestion oxidic ores forth. As well as sulfuric acid, you are usually not oxidized at the anode in a process according to the invention, but concentrated. Furthermore, the use of halogen-hydrogen acids may also be considered. Unlike the previously mentioned their anions can be oxidized to the corresponding halo, which in turn are used as anodically generated connections to shed Kings ^¬ nen. In the case of the solution sulfidic ores with sulfuric acid, for example, sulfuric acid can be regenerated by burning of produced H ₂ S from the solution of sulfide ore in air with energy gain (power station suitable) again. According to certain embodiments, the compound of the metal M thus comprises or consists of a sulfide. According be ^¬ voted embodiments is used in the solution of the compound of the metal M sulfuric acid which "set forth ^¬" anodically, that is, for example, concentrated further, can be for example, iron in the oxidation state +2.:

FeS + H ₂ S0 ₄ FeS0 ₄ + H ₂ S

H ₂ S + 1, 5 0 ₂ -> S0 ₂ + H ₂ 0 - 561, 97 kJ This means that even the energy of the sulfur in the oxidation state -2 be used from the ores without you at ei ^¬ nem roasting of the ore is lost. An H ₂ S gas burner would be in this case also much easier to construct and operate as for example a "roast burner" with solid "fuels".

H ₂ S + O ₂ ~ * H ₂ O + SO ₂ ^ H ₂ SO ₃ and further reaction (forced oxidation) to sulfuric acid S0 ₂ + H ₂ 0 + 0 ₂ H ₂ S0 ₄ .

In the method according to the invention, two different embodiments are possible, with which the at least one compound of the metal M can be converted into an aqueous solution, in which therefore the at least one compound of the metal M can be reacted such that a cation of the metal M in an aqueous Solution passes. These are schematically shown in Fi gures ^¬ 1 to 5. On the one hand comprising at least one compound of the metal M in the anode consist be or the anode even in Wesentli ^¬ chen or total of the compound of the metal M, so that the anode is as it were dissolved in the electrolysis by an anodic reaction and the metal cations M in the electrolyte, for example the anolyte - or in general but in the only one electrolyte, for example, if no membrane and no diaphragm are present transition. This is illustrated in FIG. 1, whereby in step 1 a dissolution of at least one compound of the metal M, for example M _x Y _y , as shown in FIG. 2, is carried out at an anode so that a metal cation M ^{Y + is} in aqueous solution , This metal cation wanders in step 2 to Katho ^¬ de, and there is deposited in step 3 as metal M at the cathode. Schematically, these operations are Darge ^¬ represents by arrows for an abstract electrolysis cell in Figure 2, wherein the compound M _x Y _y is converted into an aqueous solution at the anode A, the metal cation M ^{Y +} to Ka ^¬ Thode K migrates and there as the metal M is deposited in the deposition 10 in the form of a cathode. The deposition takes place here during the electrolysis by reduction of the metal ^¬ cation by means of a power source, not shown. In the exemplary compound M _x Y _y , Y ^{x + represents} a suitable represents the counterion of the cation M ^{Y +} in the compound of the metal M, which is not restricted, and x and y each denote the valency of the counterion and the metal cation, where x and y are positive, preferably integer, numbers.

On the other hand at least one compound of metal M may be also achieved by an anode prepared in the electrolysis cell compound, said Herge ^¬ presented at the anode compound is not particularly limited insofar as it can dissolve at least one compound of the metal M. Also, the location of the solution of the at least one compound of the metal M is not limited in this case, and a solution may take place inside the electrolytic cell by, for example, introducing the at least one compound of the metal M into the electrolytic cell, for example, an anode compartment, or by reacting the compound produced at the anode is brought outside the electrolytic cell for at least ei ^¬ NEN compound of the metal M is pumped, for example, through a pipe there, etc., and dissolved therein so that the compound of the metal M then in an aqueous Lö ^¬ solution is transferred, which in turn is then introduced into the electrolysis ^¬ cell, for example, to a catholyte.

This is shown schematically in FIGS. 3 to 5. In FIG. 3, the reaction sequence is shown schematically, analogously to FIG. 1. Here, step 1 of FIG. 1 is replaced by steps la, lb and lc, in which case steps 2 and 3 correspond to those of FIG. Step 1 of Figure 1 is divided in accordance with sub-steps, which then, however, again providing the metal cation in the result, which is then redu in Step 3 ^¬ for using movements in step 2. In step la of FIG. 3, the production of a compound Z takes place, which can optionally be converted into a compound Z *. The compound Z or the compound Z ^* is then used in step 1b for dissolving the compound of the metal M, for example M _x Y _y , so that once again a metal cation M ^{Y +} goes into aqueous solution, which ches then in step lc to migrate to the cathode bereitge ^¬ represents is, either in the electrolytic cell is bereitge ^¬ represents or is introduced into the electrolytic cell, then the required solution of the compound of the metal M outside the electrolytic cell. Schematically, these processes are through

4 illustrates the variant in which the compound Z, for example chlorine, produced at the anode is used directly for dissolving the compound M _x Y _y , so that these are in an aqueous solution is transferred, during which ^* is converted into a compound Z, a compound Z, for example an acid or also a H ⁺ ion produced in Fi ^¬ gur 5, such as sulfuric acid, the _x for releasing the Verbin ^¬ dung M Y _y is used. It should be noted that the ions of the metal M to be deposited may under certain circumstances be strong so-called cation acids, for example for Fe ³⁺ in, for example, Fe ₂ (S0 ₄ ) 3, owing to their high Lewis acidity.

Fe ³⁺ + 6H ₂ 0 "H ⁺ " + [Fe (OH) (H ₂ O) ₅ ] ²⁺

In both of the above cases, the metal cation M ^{Y +} again travels to the cathode K analogously to FIG. 2, where it is deposited as a precipitate 10. In this second embodiment, in this case, the "compounds" Z and Z ^{* are} not particularly limited, although here they are exemplified as chlorine and

Sulfuric acid are indicated. In this second execution ^¬ form, the step that at least one compound of the metal M is transferred to the at least one anode Herge ^¬ prepared compound into an aqueous solution by means of a and is introduced into the electrolysis cell thus also that the at least one anode can also be an ion, and / or that also the compound prepared at the anode is converted to a further compound.

The dissolution of a compound of the metal M, for example, ores, in certain cases, a direct anodic Include oxidation of the metal. Thus, the oxidation state of the metal in the anode need not match that of the metal ion dissolved. As an example, the smelting of siderite ore (FeCOs) can be cited. eg

2FeC0 ₃ + 3H ₂ S0 ₄ -> Fe ₂ (S0 ₄₎ ₃ + 2C0 ₂ + 2e ^"+ 2H ⁺ Further, containing the compound of the metal M beispielswei ^¬ se an ore also tasteful components and / or the anode metal scrap contain.

Fe - »Fe ₃ ⁺ + 3e ^~

In the method of the present invention, the cathode is not particularly limited insofar as the metal M can be deposited thereon. It can be provided in any form, for example as a solid electrode and / or electrode sheet, porous electrode, etc. and in any form auftre ^¬ th, for example, as a strip, pen, cylinder, etc. Gas ^¬ diffusion electrodes are not necessary here erfindungsge ^¬ Mäss but also not excluded. The cathode - as well as the anode and also the entire electrolysis cell or the electrolyzer, can also be constructed in plate design or concentric. For example, with rotating cathodes with scrapers for the metal, a concentric design may be advantageous. The cathode can be either inside or outside.

According to certain embodiments, the at least ei ^¬ ne cathode, the metal M is, for example, coated with the metal M, or consists essentially of the metal M. In principle, it should be noted in this regard that then developed no catalysts for the electro-chemical deposition of the metal M In particular, the overvoltage of the deposition can be reduced to 0 as soon as the Electrode consists of the metal to be deposited itself. Also, the cathode can be made of the metal M, for example, if this has a good conductivity. According to certain embodiments, the metal M is removed from the at least one cathode continuously or discontinuously after the electrochemical deposition. The at least one cathode is preferably changed or stripped Me ^¬ tall M of the at least one cathode.

In addition, in the present process, the anode is not particularly limited, and indeed any anode material can be used here in the second execution ^¬ form which is usable for preparing a compound for releasing the connection of the metal M.

According to certain embodiments, the at least ei ^¬ ne anode at least one compound of the metal M or be ^¬ is the at least one anode essentially of at least one compound of the metal M, as shown in the first embodiment. 100% by weight of the Verbin ^¬ dung of the metal M, for example, one or more ores of the metal M, or mixtures thereof: - According to certain embodiments, the anode comprises a share of 20.. Suitable additives are, for example, graphite and / or binder, the binder not being limited. To improve the conductivity of the anode, however, "metal scrap" can also be added or used directly, and consequently, for the processing of scrap, it can, for example, also be quite complete

Scrap exist, in which case in an upstream step, only the connection of the metal M can be produced, for example by no oxygen at the anode is released ^¬ , but the scrap is oxidized. According to certain embodiments, the anode comprises a

Combination of iron, in particular iron ore, or consists essentially thereof. The at least one anode can For example, consist of a combination of iron, such as iron ore.

In the method according to the invention, at least one membrane and / or at least one diaphragm may be provided in the electrolysis cell, so that, for example, an existing one

Electrolyte in an anolyte on the anode side and a

Catholyte can be divided on the cathode side, or it can also be provided no membrane and no diaphragm, so that only one electrolyte is present.

The nature of a membrane can then ultimately affect the precise operation in the process of the invention.

1. For example, a cation-conducting membrane may be vorgese ^¬ hen, which is not particularly limited. Here, the charge compensation process of the invention during electrolysis can take place mainly through cations which migrate from the anode side to the cathode side, ie for example via the metal cations, such as for those shown in Figu ^¬ ren 1 to 5 embodiments. With sulfuric acid protons for charge transport, for example, contribute ^¬. Alternatively, chloride-containing compounds such as HCl or NaCl can be used in the electrolyte, which then allows a chlorine production, which provides further synergies. The coupling of chlorine production with metal production will be considered separately below. Also proton-conducting membranes can be used, game, when the compound of the metal M is not dissolved in the electrolytic cell at ^¬ but outside by an anodic connection made, and for example, the Lö ^¬ solution, which then contains metal cations, then in the cathode denraum to Deposition of the metal M is introduced. This is indicated for example in Figures 3 to 5, so the Ver ^¬ bond of the metal M is not present in the electrolysis cell. 2. It is also possible to use an anion-conducting membrane, which is also not particularly limited. Anionleitende membranes can then, for example, in addition to hydroxide ions also other ions such as hydrogen carbonate, fluoride or sulfate hydrogen sulfate lead, in which case the compound of the metal M outside of the electrolytic cell ge ^¬ triggers and the solution is introduced including metal cations in the Ka ^¬ method space, such as this is indicated, for example, in FIGS. 3 to 5, so that the connection of the metal M is not present in the electrolysis cell. If in such a case, for example, the catholyte is preferably fluoride- or sulphate-containing, an enrichment of HF or sulfuric acid in the anolyte may also take place in this way.

3. Also, in the process of the present invention, a diaphragm may be provided in the electrolysis cell, which is also not particularly limited. For example, serve to a gas separation into catholyte and anolyte Dia ^¬ Phragmén of polymer (Polysulfone) or inorganic materials (zirconia or Zirkoniumphoshat) or with orgasmic ^¬ African polymeric materials filled polymers, for example in a water electrolysis, where anodic oxygen is produced, or in an anodic production of chlorine. With regard to the electrical ionic conductivity, they include both cationic and anionic conductivity and are therefore also suitable for the migration of metal cations, so that they can be used when using an anode comprising the compound of the metal M, as shown in FIGS. 1 and 2. Of course, however, the embodiment schematically shown in Figures 3 to 5 is possible.

4. In addition, a mode of operation without a membrane and oh ^¬ ne diaphragm is possible, although possibly compromises in the purity of individual media due to their mixing are possible. Looking at the overall system, these operations may, however, ^¬, under certain circumstances a cost electrolytically pose. Again, an operation with an anode comprising the connection of the metal M is possible, as shown in Figures 1 and 2. Likewise, the embodiment shown schematically in FIGS. 3 to 5 is also possible here.

If a membrane or a diaphragm is present, in the method according to the invention the anode and / or cathode may rest against the diaphragm or the membrane or not, so that an electrolyte gap may or may not be present. The design of the electrolyzer can be adapted to the particular metal or Güns ^¬ tigsten operation. For example, in the case with an acid, for example sulfuric acid, as anolyte, types of electrolytes with or without electrolyte gaps on the anode side are conceivable. For separation of the metal, however, one, for example minimal, electrolyte gap on the cathode side is advantageous. Alternatively, the electrodes such as a cathode could be persuaded away ^¬ ran from a Memb or a diaphragm according to the deposition rate of the metal M. In one approach, the anode, however, an electrolyte gap can be anode-side form, this was not present at the start.

In the method of the present invention, an electrolyte in the electrolytic cell is not particularly limited insofar as it is aqueous at least on the anode side. It can be provided an electrolyte for the entire electrolysis cell, for example ^¬ in a mode without membrane and without diaphragm. If a diaphragm and / or a membrane is present, the electrolyte can be divided at least into the anolyte on the anode side and the catholyte on the cathode side, with the anolyte and catholyte then being the same or different.

The catholyte is then not particularly limited. However, the ions of the metal M can form the strong themselves due to their high Lewis acidity so-called ^¬ cation acids under certain circumstances, such as for example Fe ³⁺ in Fe ₂ (S0 ₄₎ 3: Fe ³⁺ + 6H ₂ 0 ^ "H ⁺ " + [Fe (OH) (H ₂ O) ₅ ] ²⁺

Therefore, depending on the metal, it may be necessary to add pH-adjusting additives to the catholyte to avoid the undesirable formation of hydrogen at the cathode. Care should be taken here that such an additive can not be converted cathodically and preferably neither cathodically nor anodically, and in particular at the same time does not impair the solubility of the metal M to be deposited, for example by precipitation of metal cations. Such pH-regulating additives are preferably weakly basic salts having a pH of more than 7 to less than 10 when dissolved in water, which in particular simultaneously increase the electrical conductivity of the electrolyte. As known examples of such At ^¬ sets carbonates, borates or fluorides may be mentioned, in particular of alkali metals or of the metal M itself, but this depends on the solubility of the entspre ^¬ sponding weakly basic salt of the metal M in a watery solution can. In the case of iron, for example, the first two would be unsuitable due to the formation of sparingly soluble salts, so that preferably fluorides can be added here. In the case of zinc, the use of borates is again easily possible. Analogous considerations for the other metals M are familiar to the expert, so that the

Professional can determine a suitable additive suitable for pH regulation.

According to certain embodiments, a catholyte at the cathode of at least one weakly basic salts, and in particular ^¬ sondere fluorides, carbonates and / or borates, preferably Fluo ^¬ ride and / or borates are added. Also or alternatively, one or more conductive salts can be added to the catholyte to improve the conductivity, for example a solution of a - second - compound of the metal M, for example a salt. This may, for example, correspond to a salt which, upon release of the - first - compound of the measurement Talls M corresponds, for example, a sulfate at a Lö ^¬ sen with sulfuric acid, or a chloride when dissolved with chlorine or HCl, or a fluoride when dissolved with HF or KHF. ₂ Also or alternatively, compounds may be added to the catholyte, which are needed for the production of an alloy, for example chromium salts, if chromium steel is to be produced, etc.

According to certain embodiments, a catholyte at the at least one cathode consists of an aqueous solution of a - second - compound of the metal M and optionally at least ei ^¬ ner further compound of an alloying component and optionally one or more weakly basic salts. The - second - compound of the metal M in the aqueous solution is preferred in this ^¬ Lö from the - first - metal compound, which is converted into an aqueous solution, ver ^¬ eliminated. In certain embodiments, water is removed from a catholyte at the at least one cathode. This can then be maintained the conductivity when the metal cations are deposited. The method by which the water is withdrawn is not particularly limited, and includes, for example, evaporation, drying with a suitable desiccant, etc.

Also, an anolyte is then not particularly limited. This can be adapted to the anode reaction and / or the compound of the metal M, which can additionally be optionally egg ^¬ ne adjustment to the effect here, too, whether the compound of the metal M included in the anode is present in the anode compartment or outside , According to certain embodiments, as an anolyte a säu ^¬ acid, preferably sulfuric acid, or a halide-containing (in particular chloride, bromide or iodide-containing), forthcoming added to chloride-containing compound used. With these, a dissolution of the connection of the metal M can be supported or a means for releasing the connection of the metal M can be provided.

According to certain embodiments, a halogen, preferably chlorine, sulfur and / or an acid, for example sulfur ^¬ acid is produced by oxidation of water, anodic. The production of an acid here comprises the anodic production of protons and the subsequent production of an acid.

According to certain embodiments, the process according to the invention, preferably in aqueous media, can be carried out at temperatures below 120 ° C., preferably below 100 ° C., for example below 80 ° C. This temperature is significantly reduced, in particular compared to the blast furnace temperature, so that here is a saving of energy, in particular ^¬ special of waste heat, clearly. According to the invention it is also possible to perform several invention ^shown SSE process in successive electrolytic cells, for example when more than one metal M, for example, a mixed ore or electrical, to be separated off from a compound of the metal M, which has more metals M, wherein the resolution can then take place, for example, at an anode and / or with an anodically produced compound, but the deposition of the metals M can then take place at different cathodes, for example by selecting the corresponding cell voltages accordingly. A solution of the metal M, which then contains more metal cations for an Abschei ^¬ extension of a first metal M, may then be placed in a more suitable electrolytic cell, or it may be exchanged in the cathode of an electrolytic cell, etc.

Whereas the individual steps of the process according to the invention and the constituents of the electrochemical Lysis cell and materials such as electrolytes, etc. have been described above, the linkage of these components is now shown in an exemplary method, which does not limit the inventive method on the basis of exemplary embodiments. Rather, thus the manifold possible linking of the individual ^¬ nen steps and components is shown to illustrate the fiction, ^¬ proper procedures even further, without the

Basic idea of the invention restrict here.

In a first exemplary embodiment, it is proposed to use sulfuric acid as the anolyte. This has the advantage that the acid can be anodically concentrated by electrolysis of water.

H ₂ 0 - 2e ^" -> H 0 ₂ + 2 H ⁺

The electrolysis process can then proceed, for example, as follows:

The cathode chamber is continuously deposited, the solution of the salt of the metal M, which is anodically or au ^¬ ßerhalb the anode compartment of the mixture with sulfuric acid it ^¬ testifies added and deposited by electrolysis on the cathode. The deposited at the cathode metal (eg iron, cobalt, nickel and / or manganese) can be removed continuously or discontinuously from the cathode. For this example, either alternately cathode plates or a rotating cathode can be introduced into the electrolyte. The cathodes preferably consist of or are coated with the metal to be deposited, thereby limiting the overvoltage of the deposition to the diffusion overvoltage. In the thermodynamic limiting case, this overvoltage for the same metals is 0. The catholyte can also be continuously withdrawn water to maintain the conductivity. Enriched foreign metals with higher normal potential can in analog Be obtained in sequence electrolyses. Thus, the successive electrolyses also represent a metallurgical purification process. Here, catholyte and anolyte can be separated by a membrane.

Sulfuric acid is used as anolyte in this exemplary embodiment, as described above, since it concentrates rather than dilutes during electrolysis.

H ₂ 0 - 2e ^" -> H 0 ₂ + 2 H ⁺

For example, when using a proton exchanger membrane, as many protons can migrate into the cathode space to equalize the charge of the current flow, as are generated during the electrolysis at the anode. Since each proton 2-4 Wassermo ^¬ leküle transported through the membrane, the re Schwefelsäu ^¬ is concentrated during the process. The concentrated acid can then be used again for wet ore exclusion. When using an AEM, for example, sulfate ions can migrate from a catholyte into the anolyte and form sulfuric acid with anodically generated protons, which also leads to a concentration. In INTENT a diaphragm, a mixture of two Pro ^¬ processes would be present, the conductivity was not affected by the presence of polyvalent metal ions.

In addition, in operation of the electrolysis, according to certain embodiments, the concurrent evolution of hydrogen should be minimized. On the one hand, this lowers the energy yield, on the other hand it can lead to an increased porosity of the deposit and thus to the undesired inclusion of the electrolyte in the metal. This can be ensured by suitable choice of the cathode, as also described above. It should be noted that the addition of metal salt solution as in a chlor-alkali electrolysis via the anode compartment SUC ^¬ gene could, as the metal cations be generated outside of the anode chamber, but also the metal cations by dissolving an anode comprising the compound of the metal M, here ^¬ can be made. In particular, polyvalent cations be ^¬ but because is difficult by a cation-conducting membrane or even block them, so this is not preferred. Here, for example, the use of a diaphragm can also remedy the situation.

The operation shown here includes the Regenera ^¬ tion and even concentration of the anolyte during the electrolysis process.

According to the invention, however, are not ^{oxygen-¬-producing} anode reactions, such as a

Chlorine production, which is shown below in a second exemplary embodiment. This is preferred, but other halogens such as bromine or iodine can also be produced.

In particular, the chlorides of the metal M can be very well electrolyzed due to their good solubility and thus high conductivity of the electrolyte. The halogen can in

Once it has been generated, for example, from the naturally occurring in huge amounts of sodium and / or potassium chloride anodic. With this chlorine, the compound of the metal M, for example, one or more oxides, then dissolved and converted into Chlo ^¬ ride, for example, outside of the anode compartment. This reaction is also suitable in the presence of carbonates as a compound of the metal M. This is then a

stoichiometric amount of CO ₂ free.

Μ ^{η +} _χ Ο _{(χ * η) / 2} + (x * n) / 2 Cl ₂ -> x M ^{n +} Cl _{(ri * x)} + (x * n) / 4 0 ₂ Subsequently, the metal chlorides are electrolyzed and recovered the pure metals, wherein the electrolyte can be continuously fed metal chloride. The resulting chlorine can the release process, for example the roasting may be performed again to ^¬.

M ^{n +} Cl _{(ri * x)} -> n M + (x * n) ₂ Cl ₂ In this arrangement, for example, the operation of the electrolyzer without membrane is preferable, since no liquid anolyte must be handled.

Another exemplary, third embodiment without membrane represents an arrangement where the iron ore is in the immediate vicinity of the anode and anodic acid is generated. The protons produced in aqueous media thereby solve the ore (for example, an oxide) and provide for a continu ous ^¬ replenishment of metal ions which can be decorated at the cathode reduced. The acid formation is stoichiometric, so as much metal goes exactly in solution, as deposited at the Katho ^¬ de. The system can be operated continuously. The above embodiments, refinements and developments can, if appropriate, be combined with one another as desired. Further possible refinements, developments and implementations of the invention also include combinations of features of the invention which have not been explicitly mentioned above or described below with regard to the exemplary embodiments. In particular, the person skilled in the art will also add individual aspects as improvements or additions to the respective basic form of the present invention. The invention will be described below with reference to various

Examples of this are explained in more detail. However, the invention is not limited to these examples. Examples

Example 1 :

In a first example, iron ore comprising iron oxide and iron sulfide is dissolved in various oxidation states either as an anode material or in an anode space by means of protons or oxonium ions produced in a water electrolysis, or generally with acid.

Anode reaction: H ₂ O - * H 0 ₂ + 2 H ⁺ + 2 e ^"

Dissolution of ores:

Fe ₂ 0 ₃ + 6 H ⁺ -> 2 Fe ³⁺ + 3 H ₂ 0

Fe ₃ 0 ₄ + 8 H ⁺ -> Fe ³⁺ + Fe ²⁺ + 4 H ₂ 0

FeS + 2H ⁺ -> 2 Fe ²⁺ + H ₂ S

Here in the ore also contained, for example, iron carbonate ^¬ th can be:

FeC0 ₃ + 2 H ⁺ -> Fe ²⁺ + H ₂ 0 + C0 ₂

Iron ores here have a conductivity that comes close to that of graphite, which makes the process even more attractive here.

The anode can in this case for example, from 20 - 100 weight% consist egg ^¬ senerzen, wherein for example, graphite may be added ^¬ beat..

The iron ions anodically produced can then be deposited on an iron cathode as the iron and this perio ^¬ disch removed or stripped. However, the illustrated cathode reaction can also be coupled with various anode reactions, for example for the production of acid. be pelt so that also various ores can be processed easily.

Exemplary basic data for various electrons of iron ores are given in Table 2 below.

Table 2: Thermodynamic data for the solution of iron ores as anode material

Z: number of transmitted electrons

Example 2

In a second example of the present process anodes are used, which in an amount of 20 -100 wt. % of these ores, or mixtures thereof, e.g. Iron oxide. As a supplement, for example graphite comes into consideration. To improve the conductivity of the anode, however, "metal scrap" can also be used directly, and consequently, scrap can be made entirely of scrap metal, in which case no oxygen is released at the anode, but the scrap is oxidized.

The following reactions, for example, result for divalent iron, which, however, can also result analogously, for example, for divalent Co, Ni or Mn, etc.

Anode reaction: Fe - * Fe ²⁺ + 2e ^~

Cathode reaction: Fe ²⁺ + 2e ^~ - * Fe

In particular, in the methods, if appropriate, the resistance in Qm ² / m, which is specific to the minerals, should also be considered in order to be able to produce suitable anodes with sufficient conductivity, for example. :

Graphite -5

10 ^' Gm

Magnetite Fe ₃ 0 -2

4 10 ^' Gm

Pyrite FeS ₂ 10 ^' -5 - 10 ^"2 Sq

Hematite Fe ₃ Ü ₄ 10 ^' -2 - 10 Gm

Iron Fe 10 ^' -7 Qm

In Science, 26 Sep 2014; Vol. 345, 6204, pp. 1593-1596; DOI: 10.1126 / science.1258307;

http://science.sciencemag.org/content/345/6204/1593) is ge ^¬ shows that iron oxides are good oxygen generating catalysts (OER). However, these are stable only at high pH values. This instability at neutral and acidic pH and accompanying resolution, while reducing the overvoltage is present a special advantage. This is an energy-efficient resolution of the ore over ^¬ all possible. The same applies to the metals Co, Ni and Mn, for the benefits erge ^¬ ben in the same manner.

Example 3:

In a third example, a sulfidi ^¬ ULTRASONIC ore, such as iron sulfide, given anode is used as anode, wel ^¬ ches can be solved by an anodically produced acid. The actual anode reaction can then be the Wasseroxi- dation.

Alternatively, if the sulfide ores are directly electrically coupled, the sulfide can be oxidized to sulfur directly at the anode. The resulting sulfur then floats on top of the aqueous anolyte solution and can be skimmed off from the electrolyte. The sulfur can be used for example for the Gummiherstel ^¬ development, production of sulfuric acid, etc.. In the event of an oversupply, however, it can easily be dumped without causing environmental damage. Such an electrolysis ^¬ cell requires very low voltages, since the anode ^¬ voltage is only +0.14 V (S ^{2 ~} (s) + 2H ⁺ + 2e- ^ H ₂ S (g)).

Anode reactions:

FeS -> Fe ²⁺ + S + 2e ^" or FeS ₂ - * Fe ²⁺ + 2S + 2e ^~

The cathodic deposition of the metal takes place as indicated above with ^¬ game as in Example 1 or the second

In the present case, comprehensive electrochemical processes from ore to metal are described. The anode reaction is used simultaneously to produce reagents (sulfuric acid or chlorine) needed for ore processing. This will theoretically maximize possible

Faraday efficiency of 200% is used because both oxidation and reduction are used for metal production. The total Systems are thus self-supporting in particular advantageous Ausgestal ^¬ obligations.

The present invention represents a disruptive approach, which converts the previous metal-producing industry to the fundamentally new reducing agent "electrons from renewable energies." Blast furnaces can thus become superfluous and be converted to electrolyzers with aqueous electrolytes.

Claims

claims

A process for producing a metal M selected from Ti, V, Nb, Ta, Cr, Mo, W, Mn, Re, Fe, Co, Ni, Cu, Zn, Cd, Ga, In, Tl, Ge , Sn, Pb, As, Sb, Bi, Se, or Te, and / or a mixture and / or alloy thereof in an electrolytic cell comprising at least one anode and Minim ^¬ least a cathode, wherein a compound of the metal M, and optionally at least one further Compound of an alloying BeStteils is transferred into an aqueous solution and the Me ^¬ tall M and / or a mixture and / or alloy thereof is electrochemically deposited on the at least one cathode, wherein the at least one anode comprises the compound of the metal M, preferably in Substantially consists of the at least one compound of the metal M, and the at least one compound of the metal M is electrochemically transferred to the at least one anode in an aqueous solution, and / or wherein at least one compound of the metal M by means of a at the at least one anode h compound is transferred into an aqueous solution and is introduced into the electrolytic cell.

2. The method of claim 1, wherein the at least one Ka ^¬ method comprises the metal M or consists essentially of the metal M tall.

3. The method of claim 1 or 2, wherein a catholyte at the at least one cathode weakly basic salts, in ^¬ particular fluorides, carbonates and / or borates are added.

4. The method according to any one of the preceding claims, wherein a catholyte at the at least one cathode from a dcr aqueous solution of a compound of the metal M and optionally at least one further compound of an alloying component and optionally one or more weakly basic salts.

5. The method according to any one of the preceding claims, wherein the metal M is removed after the electrochemical deposition continuously or discontinuously from the at least one cathode, preferably wherein the at least one cathode is changed or the metal M is stripped from the at least one cathode.

6. The method according to any one of the preceding claims, wherein a catholyte is removed at the at least one cathode water.

7. The method according to any one of the preceding claims, wherein as the anolyte an acid, preferably sulfuric acid, or a halide-containing, preferably chloride-containing, compound is used.

8. The method according to any one of the preceding claims, wherein anodically a halogen, preferably chlorine, sulfur and / or an acid is prepared.

9. The method according to any one of the preceding claims, wherein the compound of the metal M comprises an oxide and / or a sulfide or of an oxide and / or a sulfide of the metal M be ^¬ .