RU2425177C1 - Method of electrolytic production of metals with simultaneous deposition of admixtures - Google Patents

Abstract

FIELD: electricity.

SUBSTANCE: in an electrolytic cell, which comprises a cathode, an anode and collectors of admixtures dissolved in electrolyte, arranged as electrodes, potential of which is maintained as more positive than the potential of metal recovery and more negative than the potential of admixtures recovery, collectors are installed on a trajectory of intensive electrolyte circulation and are joined into an electric circuit so that the first collector has the most positive potential, the last collector has the most negative potential, and maintenance of the required potential of collectors is ensured through control of the force of the current passed through each of the collectors by means of resistance variation on the circuit sections of cathode-collector or variation of electromotive force of polarisation of additional current source in the anode-collector circuit on the basis of measurement or calculation of electromotive force value between the cathode and each of the collectors. To calculate value of electromotive force between the cathode and each of the collectors, forces of the current passed through the cell are measured, as well as forces of current passed through the collectors, voltages between the anode and the cathode, voltages between the anode and the collectors, voltages between the cathode and the collectors, and calculation is made using a method of singular decomposition. Direct measurement of electromotive force between the cathode and each of the collectors is carried out immediately after disconnection of the current passed through the electrolytic cell.

EFFECT: opportunity to separately deposit admixtures of the specified composition to prevent contamination of the target production and to recycle extracted admixtures.

7 cl, 6 dwg, 1 tbl, 2 ex

Description

The invention relates to ferrous metallurgy, in particular to the production of metals and alloys by electrolysis of molten salts

In the electrolytic production of metals at the cathode, along with the target product, the impurities present in the electrolyte are precipitated. The source of impurities can be raw materials for the production of metals and corrosion products of the structural elements of the electrolyzer (anodes, cathodes, lining, etc.). Impurities co-precipitating together with the cathode metal usually form alloys with it. Purification of the obtained alloys from impurities is not always possible, or requires the use of expensive methods (electrolytic refining, zone melting, recrystallization, etc.). Therefore, it is advisable to prevent significant precipitation of impurities together with the target metal during electrolysis. Obtaining pure raw materials and the use of more resistant materials in the design of the electrolyzer can significantly reduce the pollution of the metal obtained by electrolysis. At the same time, these measures will lead to a significant increase in the cost of production.

The prototype of the invention (application US 2006/0185984) describes the principle of preventing contamination of the cathode metal by impurities by installing impurity collectors in the electrolysis cell, which are cathodes with a potential that is more positive than the target metal recovery potential and negative than the reduction potential of impurities that are more electropositive than the target metal. As a result of this, part of the impurities is restored on the collectors, which reduces the degree of contamination of the target metal. According to the prototype, the collectors are placed so that the electrolyte enriched with impurities first washed the surface of the collectors, and then approached the surface of the main cathode. This allows you to improve the efficiency of cleaning the electrolyte from impurities and, therefore, to reduce the amount of impurities that are restored at the cathode. Collector polarization according to the prototype is carried out by connecting them to the cathode or cathode busbar through additional resistance or by connecting them to a current source or by arranging the collector so that the metal dissolved in the electrolyte that has a more electronegative potential than the potential of impurities serves as an electron source for reducing impurities. The collector potential of the prototype should be 0.5-1.5 V more positive than the cathode

The disadvantage of the prototype solution is that all impurities having a more positive deposition potential than collector potential are deposited on the collectors. At the same time, separate deposition of impurities on different collectors would make it possible to obtain several other metals and alloys during electrolysis in addition to the base metal, the cost of which may even be higher than the cost of the main electrolysis product. So, for example, in the production of aluminum with inert metal anodes, in addition to aluminum, it is possible to obtain alloys or individual metals, which during electrolysis transferred to the electrolyte when the anodes dissolve. Thus obtained metals and alloys can be further used for the manufacture of new inert anodes, which reduces the cost of producing aluminum.

Another disadvantage of the prototype solution is that it does not define a method for setting the potential value (or current strength) on the collector. Since the collector potential during current transmission depends on its location in the cell and the voltage on the cell, with a collector potential in the indicated range of values, it is possible to partially recover aluminum (at low potential) and prevent the recovery of some impurities whose potential is close to the reduction potential of aluminum (silicon, titanium), which is possible with a high positive potential of the collector.

The technical result of the proposed solution is the separate deposition of impurities or their alloys of a given composition on impurity collectors in order to prevent contamination of the target electrolysis product and the secondary processing of impurities extracted from the electrolyte.

The technical result is achieved by the fact that potentials are set on different collectors, more negative than the recovery potential of the corresponding impurity. So, for example, to restore copper from cryolite-alumina melts, a potential is required (hereinafter, unless otherwise stated, the value of the potential relative to the equilibrium potential of aluminum without an ohmic contribution is indicated), more than 1.8 V relative to the equilibrium potential of aluminum, and for the reduction of iron and nickel collector potential should be less than 0.7 V and 1.2 V, respectively [1]. Thus, copper will mainly deposit on a collector with a potential in the range of 1.4-1.8 V. By placing the collector in the path of the electrolyte flow and setting the corresponding potentials on them, it is possible to isolate alloys enriched in one of the elements dissolved in the electrolyte on each of the collectors. In this case, the very first collector in the path of electrolyte flow should have the most positive potential, and the most recent most negative. In this case, only the most electropositive impurity will be deposited on the first collector, and the most electronegative impurity on the last collector. The degree of purification of the electrolyte from impurities depends on the flow rate of the electrolyte and the development of the surface of the collectors, i.e. from the fairness of the surface of the collectors at any point in the stream. Some impurities, the recovery potential of which is more positive than the reservoir potential, may not settle on the first collector and will be restored on collectors with a more negative potential. Thus, almost pure metal can be obtained only at the first, most electropositive collector. Alloys enriched in an element whose potential is less than the potential of the previous collector will be deposited on subsequent collectors. For example, in the case of contamination of the electrolyte with dissolved compounds of copper, nickel and iron on collectors arranged so that the collector with a potential of 1.7 V is the first in the path of the electrolyte flow, copper enriched in the second 1.1 V and the third 0.6 V for nickel, Cu-Ni alloy and iron-enriched Cu-Ni-Fe alloy, respectively.

The collector system should be located along the trajectory of intense electrolyte circulation in order to increase the efficiency of cleaning the electrolyte from impurities.

Maintaining the desired potential is provided by regulating the strength of the current passed through each of the collectors. The required current strength is determined empirically and depends on the concentration of impurities in the electrolyte and its speed along the collector surface. Passing a greater cathode current through the collector than is necessary to restore one of the impurities leads to a negative potential shift and the beginning of deposition of an impurity on the collector, which has a more negative deposition potential. Passing a current of too small a value will not provide the necessary purification of the electrolyte from impurities and will lead to deposition on collectors of alloys enriched in impurities, which should have been restored on collectors with more positive potentials. Regulation of the current is carried out either by adjusting the resistance in the cathode-collector circuit section, or by means of the current source in the cathode-collector circuit section (see Figs. 1, 2, 3).

Unlike the prototype, which does not describe how to choose the values of the collector potential and the current passed through them, in the proposed solution, the regulation of these parameters can be performed based on the measurement or calculation of the magnitude of the emf between the cathode and each of the collectors. This allows you to set the potential and current strength, which provide greater purity of the deposited metal on each of the collectors and a greater efficiency of cleaning the electrolyte.

The measurement of the potential of the collectors relative to the potential of the cathode when selecting the current strength can be performed by turning off the current of the main circuit of the electrolyzer and subsequent direct measurement of the EMF of the collector-cathode circuit.

The principle of calculating the EMF of the collector-cathode circuit without turning off the main circuit current is described below in the corresponding section.

As a percentage, no more than 10% of the current passing through the cell is passed through the collectors.

Collectors should be made of material that will not undergo anodic oxidation or dissolution when the potential for reduction of the corresponding impurity is imposed. For example, a collector made of iron cannot be used for copper deposition, since iron will dissolve anode at the potential for deposition of copper from the electrolyte. In one embodiment, any of the collectors can be made of that metal, which, in accordance with a given potential, should be mainly restored on this collector. In other words, the collector on which copper will be deposited must be made of copper, and a nickel collector, etc., should be used to deposit nickel. In another embodiment, all the collectors can be made of metal, which in terms of recovery potential is equal to or more positive than the potential set on any of the collectors. For example, copper collectors can be used to deposit copper, iron and nickel.

To effectively clean the electrolyte from impurities, the collectors must have a shape characterized by the most developed surface. One of the options may be the manufacture of collectors in the form of a grid or lattice with a large cell (5-50 mm). With a smaller cell size, it can be blocked by a precipitate of reduced impurities, which will complicate the circulation of the electrolyte through the collector and reduce the efficiency of cleaning the electrolyte from impurities, which will require removing the collector from the electrolyte and cleaning it of the deposited impurities. Thus, the choice of the shape of the collectors depends on the rate of deposition of impurities on the collectors, i.e. from the purity of the electrolyte.

The metal precipitate cleaned from the collectors is an individual metal or alloy enriched in one of the elements that make up the electrolyte as an impurity. Such a precipitate can be recycled after purification from the electrolyte by known methods.

CALCULATION EMF CALCULATION PRINCIPLE CATHOD-COLLECTOR

For circuit circuit with a single collector (figure 1), you can write the following equations:

Where the values are known (measured):

I is the current flowing through the cell;

Ikk - current flowing through the collector;

Uak is the voltage of the anode-cathode;

Uakk - voltage of the anode-collector;

Ukk is the cathode-collector voltage.

Unknown quantities to be found:

Ra is the resistance of the anode;

Rk is the cathode resistance;

Rkk - collector resistance;

Re ₁ is the resistance of the electrolyte between the cathode and the collector;

Re ₂ is the resistance of the electrolyte between the anode and cathode;

Eak - EMF anode-cathode;

Eakk - EMF anode - collector;

Ekk - EMF collector cathode.

Thus, there is a system of equations (1) in which there are fewer equations than unknowns. To complement it and find all the unknowns, you can do this. Assuming that for a short time interval (within a few minutes) the current changes, we obtain sets of input data:

:We denote the sought quantities by the vector

:

(3), получим 2p+1 уравнения вида:Substituting these sets into system (1) and denoting the desired quantities by vector

(3), we obtain 2p + 1 equations of the form:

Or in abbreviated form:

A x = b.

Matrix A and the right side are composed of measurement results that have measurement errors. Therefore, the system must be solved by the least squares method, which ensures a minimum discrepancy || Ax-b ||. To solve the problem, we apply the method of singular decomposition. Note that there must be at least 6 rows in matrix A, that is, the number of unknowns in the system. It should also be noted that, the more equations, that is, the number of measurements taken, the more accurate the resulting solution.

Applying the singular decomposition procedure to matrix A [2], we obtain the following decomposition:

where H, K are orthogonal matrices, and the central matrix consists of diagonal elements γ _j, which are called singular numbers, the n-rank of matrix A.

Denote:

,

,

then the solution will look like:

If all γ ₁ , γ ₂ , ..., γ _n , which are diagonal elements of the central matrix in the singular expansion (5), are nonzero, then the system of equations is solvable and we can unambiguously find all x _j by expression (7). However, such a solution is not always correct if some γ _j are small. For the correct use of the method of singular decomposition, a boundary is introduced that reflects the accuracy of the input data.

придается произвольное фиксированное значение. С этой произвольностью значений связана не единственность набора коэффициентов, получаемых методом наименьших квадратов. Изменения входных данных и ошибки округлений, меньшие, чем заданная граница точности, могут привести к совершенно другому набору коэффициентов, определяемых этим методом. Таким образом, найдены решения с необходимой точностью. Последнее значение в векторе

, а именно x₆=Ekk, является искомым решением и равняется ЭДС катод-коллектор.Any γ _j smaller than a given boundary is considered negligible, and the corresponding expression

given an arbitrary fixed value. This randomness of values is associated not with the uniqueness of the set of coefficients obtained by the least squares method. Changes to the input data and rounding errors smaller than a given accuracy limit can lead to a completely different set of coefficients determined by this method. Thus, solutions are found with the necessary accuracy. Last value in vector

, namely x ₆ = Ekk, is the desired solution and equals the EMF of the collector cathode.

The inventive method is illustrated in figures 1-6

Figure 1 shows a circuit diagram with one collector and an adjustment resistor. A current of Ik + Ikk1 is supplied to anode 1 having a resistance Ra. The anode is connected in series with a potential jump 2 equal to φ _α , and with the space of the anode - collector 3 having a resistance of Re 2. Next, the circuit is divided into two branches - a parallel connection.

A current of Ik goes along the first branch. The space in the electrolyte between the cathode and the collector 4 having a resistance Re1 is connected in series with a potential jump 5 equal to φ _k and a cathode 6 having a resistance Rk.

A current of Ikk1 passes along the second branch. The potential jump 7 equal to φ _k1 is connected in series with a collector 8 having a resistance Rkk1, and an adjustment resistor 9 having a resistance Rom1.

The cathode 6 with the resistance Rk and the resistor 9 with the resistance Rom1 are connected to a common section of the circuit, and thus the parallel connection section is passed, and the circuit is completed.

In the above scheme, to calculate the emf of the cathode-collector circuit, the potential difference of the anode-cathode (Uak) 10, the potential difference of the cathode-collector (Ukk1) 11 and the potential difference of the anode-collector (Uakk1) 12 can be measured.

Figure 2 presents a diagram of an electrical circuit with two collectors and adjusting resistors. To calculate the EMF in this circuit, one more equation must be added to the system discussed above. There will be more unknowns, the number of measurements will also be larger, otherwise the principle of solution does not change. Let us describe the difference of the circuit shown in this figure from the case with one collector and one resistor (Fig. 1).

A third branch is added to the circuit diagram, along which current Ikk2 flows. A potential jump of 13 equal to φ _k2 is connected in series with a collector 14 having a resistance Rkk2, and a second regulating resistor 15 having a resistance Rom2. In the above diagram, it is additionally possible to measure the potential difference between the cathode and the second collector (Ukk2) 16 and the potential difference between the anode and the second collector (Uakk2) 17. Also, the space in the electrolyte between the first and second collector 18 having resistance Re3 is added to the circuit.

A cathode 6 with a resistance Rk, a resistor 9 with a resistance Rom1 and a resistor 15 with a resistance Rom2 are connected to a common section of the circuit and, thus, the parallel connection section is passed and the circuit is completed.

The difference between the circuit of the electric circuit in Fig. 3 and the circuit shown in Fig. 2 is that there are no control resistors 9 and 15, instead, current sources are added to ensure the separation of current between three branches: anode-cathode, collector anode 1 , anode-collector 2, respectively, the current is divided into three parts: Ik, Ikk1, Ikk2.

Figure 4 shows an example of the location of the electrodes in the cell according to the scheme in figure 1, where 19 is the alumina dosing system; 20 - collector rods; 21- aluminum; 22 - corundum crucible.

Upward gas flows around the anode 1 form two circulating circuits in the cell. Alumina dissolves in the electrolyte, falling into the zone of intense circulation (right loop). The dissolved impurities are transported by a moving electrolyte from the anode 1 to the side of the cathode 6, as shown by arrows, and deposited on the grid of the collector 20, which reduces the pollution of aluminum 21 flowing down from the cathode.

Figure 5 shows an example of the location of the electrodes in the cell according to the diagram in figure 2. In the electrolysis cell there are two circuits of electrolyte circulation. The difference from the arrangement of the electrodes in figure 4 is that in the interpolar space there are three collectors, one of which 8 is in the circuit with the first regulation resistor, and the other two 14 are connected in parallel to each other in the circuit section with the second regulation resistor. Due to this, on one collector it is possible to maintain one EMF value of cathode-collector 1 (Ekk1), and on two other collectors another value of EMF cathode-collector 2 (Ekk2) and, therefore, to carry out separate deposition of impurities.

Figure 6 shows the directions of convective electrolyte flows in the interpolar space of the cell shown in Figure 5. The streams carry out the transfer of the dissolved components of the anode 1 to the collectors 8 and 14, as well as to the cathode 6.

EXAMPLE 1. DESCRIPTION OF THE EXPERIMENT WITH ONE COLLECTOR AND THE RESULTS OF CALCULATION OF EMF CATHOD-COLLECTOR.

Electrolysis with an inert metal anode Cu-Ni-Fe and a collector of impurities (soluble components of the anode) was carried out at 900 ° C in an electrolyte containing 44 NaF, 49 AlF ₃ and 7 Ak ₂ O ₃ , wt.%. The collector 8 in the form of a mesh 105 * 125 mm of steel grade St3 with a mesh size of 10 × 10 mm and a diameter of rods of 2 mm was connected to an electrical circuit, as shown in figure 1, and immersed vertically in the melt so that the distance from the upper boundary the mesh to the melt mirror was ~ 2 cm (Fig. 4). The metal anode 1, cast from a Fe-Ni-Cu alloy, and a cathode from a material based on TiB ₂ 6, whose working (facing the collector) surface was 90 cm ² (h = 90 mm; l = 100 mm, a = 6 mm ), were installed parallel to the collector grid at a distance of 2 cm from it.

A current of 72 A was passed through the electrolysis cell, which, based on the area of the working surface, corresponds to an anodic and cathodic current density of 0.8 A / cm ² . Electrolysis continued continuously for 76.5 hours. During the entire time of electrolysis, alumina was introduced into the cell 22 through the automatic dispenser 19.

To measure the EMF value Ekk, the current was periodically switched off and a potential difference between the cathode and collector was measured using a voltmeter. The target value of Ekk was 0.7 V, which, as follows from the above description, ensures the isolation of each of the components of the anode alloy on the collector. By changing the resistance Rom1 on the control resistor 9, it is possible to change the value of the current passed through the collector and thereby keep the emf circuit of the cathode-collector Ekk close to the set value, providing the most complete purification of the electrolyte from impurities without the risk of going into the region of aluminum deposition potentials. 24 hours after the start of electrolysis to maintain Ekk approximately equal to 0.7 V, the current in the collector circuit was reduced from 5-6 A to 2-3 A. Thus, the steady-state current density on the collector was 15-25 mA / cm ² , and the fraction the current directed to the selection of impurities was 2.7-8.3%, which is lower than the limit specified in the description (10%).

In parallel with the measurements of Ekk, its calculation was carried out according to the above algorithm for calculating the emf of the cathode-collector circuit. According to this algorithm, for calculating Ekk, we measured {I, Ikk, Uak, and Ukk}. The input data and calculation results are shown in Table 1. In total, 4 calculations are given in the table, for each of which three consecutive measurements of {I, Ikk, Uak, Ukk} values were made when the current I changed by no more than 10 A. Check calculated values were carried out by comparing them with the measured Ekk values (meas.). It can be seen from the table that the deviation of the measured Ekk value from the calculated value is no more than 50 mV, which confirms the possibility of using the proposed algorithm to maintain the cathode-collector EMF in the optimal range of values without turning off the current on the cell.

Note that although the described measurements and calculations were made on a cell with one collector, the principle of calculation can be extended to cases with several collectors with different potentials on them.

Table 1 Results of measurements and calculations No. p / p I Ikk Uak Ukk Ekk (calculated) Eak Eakk Ekk (rev) 71.9 1,526 4,474 1.72 one 61.5 1,366 4.17 1,54 0.804 2,34 1,536 0.756 67.8 1.44 4.4 1,638 71.8 0.564 4.38 1,916 2 61,4 0.511 4.08 1,735 0.726 2,307 1,581 0.683 67.6 0.545 4.27 1,853 72 0.774 4.34 1,907 3 61.6 0.702 4.05 1,730 0.801 2,339 1,538 0.752 67.8 0.746 4.22 1,838 71.7 4,755 4,464 1,403 four 61,4 4,317 4,145 1,277 0.557 2.26 1,703 0.534 67.6 4,608 4,334 1.351

At the end of the experiment, weighing the cathode aluminum 21 showed that the current efficiency of aluminum was 55%. The purity of the cathode aluminum was 98.5%. The sediment on the collector, excluding electrolyte components and impurities that are not part of the anode (Si, Ti, Cr, Zn, S, in total less than 5%), had the following composition: 29.7 Fe, 7.9 Ni, 60.5 Cu (wt.%), Which is close to the composition of the anode alloy and indicates almost complete deposition of the anode components dissolved in the melt on the collector.

EXAMPLE 2. DESCRIPTION OF THE EXPERIMENT WITH SEPARATE DEPOSITION OF COPPER AND OTHER IMPURITIES

In the experiment, a cell with three cylindrical collector electrodes was used. The layout of the electrodes in the cell is shown in FIGS. 5, 6. In order to maximize the degree of purification of the melt from the dissolved components of the anode and to prevent their deposition on the cathode, collectors were placed between the anode and cathode on the electrolyte from the anode to the cathode. All collectors were cylindrical rods 110 mm high and 10 mm in diameter, welded to steel current leads, which were protected by alundum covers. The immersion depth of the collectors in the electrolyte was about 120 cm. The electrolyte composition, electrolysis temperature, material and dimensions of the anode and cathode were similar to those described in example 1. The current strength on the electrolysis cell was maintained equal to 61 A. The full circuit diagram is shown in figure 2 . A copper rod served as collector 8, and two nickel rods connected in parallel as collector 14. For copper deposition on a copper collector 8, an EMF of cathode-collector1 (Ekk1) of about 1.7 V was maintained. On two nickel collectors 14, an emf of cathode-collector2 (Ekk2) of about 0.9 V was supported for deposition of a Cu-Ni alloy enriched in nickel and iron -Fe. The reason for the increase in the area of the collector 14 relative to the collector 8, obviously, is the greater amount of impurities deposited at the emf of the cathode-collector 2 of about 0.9 V. The current values of Ekk1 and Ekk2 were determined by direct measurement when the electrolysis current was turned off. The current strength passed through the collectors 8 and 14, and thereby maintaining Ekk1 and Ekk2 near the target values, was adjusted by changing the resistances Rom1 and Rom2 on the control resistors 9 and 15, respectively.

After 50 hours of electrolysis, the currents on the collectors approached their stationary values, i.e. To maintain Ekk1 and Ekk2 near the target values, it was no longer necessary to adjust the resistances Rom1 and Rom2 using resistors 9 and 15. On the copper collector 8, the stationary current value was about 0.5 A (~ 15 mA / cm ² ), on nickel collectors 14 it was about 4 A (~ 60 mA / cm ² ). The fraction of the total current directed to the separation of impurities was about 7.5%, which is lower than the limit indicated in the description (10%).

After 100 hours, electrolysis was stopped. The mass of aluminum obtained was 1050 g, which corresponds to a current efficiency of about 51%. The resulting aluminum had a purity of 98.7%. As in the experiment described in example 1, the deposits on the reservoirs had a porous structure and were impregnated with electrolyte. The precipitate obtained on copper collector 8, excluding electrolyte components and impurities not included in the anode (Si, Ti, Cr, Zn, S, in the amount of less than 5%) contained 97.3 Cu, 0.2 Fe, 2 5 Ni (wt.%). Sediment on nickel collectors 14 contained on average 37 Cu, 35.5 Fe, 27.5 Ni (wt.%).

The obtained results demonstrate the possibility of conducting electrolysis with separate deposition of elements on the collectors by maintaining the corresponding values of the EMF cathode-collector. A more complete separation of impurities can be achieved by a more optimal arrangement of the collectors in the cell.

Bibliography

1. Antipov EV Electrochemical behavior of metals and binary alloys in cryolite-alumina melts / Antipov E.V., Borzenko A.G., Denisov V.M., Filatov A.Yu., Ivanov V.V., Kazakov S.M., Mazin P .M., Mazin V.M., Shtanov V.I., Simakov D.A., Tsirlina G.A., Vasiliev S.Yu., Velikodny Yu.A. // Light Metals. - 2006. - S.403-408.

2. Lawson, Ch., Henson, R., Numerical Solution of the Least Squares Method, Moscow: Nauka, 1986, 232 pp.

Claims (7)

1. The method of electrolytic production of metals in an electrolyzer containing a cathode, anode and collectors of impurities dissolved in an electrolyte, made in the form of electrodes whose potential is supported more positively by the metal recovery potential and negatively than the impurity recovery potential, including passing the cathode current through the cathode and impurity collectors to produce metal at the cathode and the deposition of impurities on the collectors, characterized in that the collectors are installed on the trajectory of intense circulation of electrolytes and they are connected into an electric circuit in such a way that the most positive potential is supported on the first collector, and the most negative potential is maintained on the last collector, and the required collector potential is maintained by controlling the current flow through each of the collectors by changing the resistance on the cathode-collector circuit sections or by changing the EMF of the polarization of an additional current source in the anode-collector circuit according to the results of measurement or calculation of the magnitude of the EMF between the cathode and each of the collector in. 2. The method according to claim 1, characterized in that the deposition of impurities is carried out on collectors made of a material that is not susceptible to anodic oxidation or dissolution with the potential for reduction of the corresponding impurity. 3. The method according to claim 1, characterized in that no more than 10% of the current passing through the cell is passed through the collectors. 4. The method according to claim 1, characterized in that the collectors have a shape characterized by the most developed surface, for example, in the form of a grid or lattice with a cell of 5-50 mm. 5. The method according to claim 1, characterized in that the impurities released on the collectors are recycled to produce the corresponding metals or alloys. 6. The method according to claim 1, characterized in that for calculating the magnitude of the EMF between the cathode and each of the collectors, the values of the current passed through the cell, the current passed through the collectors, the voltage between the anode and the cathode, the voltage between the anode and the collectors, voltage between the cathode and collectors, and the calculation is performed using the method of singular decomposition. 7. The method according to claim 1, characterized in that the measurement of the EMF between the cathode and each of the collectors is carried out immediately after turning off the current passed through the electrolyzer.

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