JPS5947392A - Purification of nickel electrolyte - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electrolytic device and an electrochemical method for removing impurities from nickel-containing solutions. More specifically, the invention relates to a nickel refining electrolyte (nickel refining electrolyte).
The present invention relates to an improved electrochemical method for removing contaminants f, = cobalt, iron, arsenic and lead from refinery electrolytes.

In electrolytic refining of nickel, the crude nickel anode is electrolytically corroded, resulting in nickel and certain impurities being dissolved in the electrolyte. The electrolyte is purified and then nickel is deposited from the purified electrolyte onto the cathode. In nickel refining work, a normal electrolyte is used to process nickel, sulfuric acid,
It is a slightly acidic aqueous solution containing sodium and chloride ions, boric acid, and impurities. There are various impurities, including metals such as cobalt, steel, iron,
One or more examples of arsenic and lead can be mentioned. In order to prevent impurities from being deposited on the cathode together with nickel, or
Remove them from the electrolyte in order to reduce the -IL
It is necessary to reduce the
Ru. The degree of removal affects the purity of the precipitated nickel, and the desired I-11 degree depends on factors such as the end use of the nickel, the refining cost, the IW degree (particularly the IW degree of the removal of nickel particles), and the value of impurities. change. For example, cobalt is −
1 Similar in nature to Balto! ,−Me nickel content (σ)
For those applications, it is desirable that nickel contaminants are not considered, and that cobalt-rich materials contain a large amount of cobalt.

t (tj (i it 1y or L-J 夾い 1 [to remove things & ,, l-111 I trace, Yang Yuzu melt)' 1 I to small ti
41 I↓14 Removal of impurities by a combination of chemical, chemical, or electrical techniques. For example, copper Q.
Gold 1. bond with nickel (cementatln)
solution by precipitation with lS or by precipitation with lS.
can be removed to very low levels. Cobalt, arsenic and lead are removed by addition of chlorine gas 7L.

Nickel carbonate is used to neutralize the acidifying effect that occurs as cobal l- and other impurities precipitate from solution. The purified electrolyte is then returned to the electrolytic cell and used for nickel plating at the cathode.

Impure decoppered nickel refining electrolyte] cobalt, iron,
Removal of Arsenic ID and/or Lead Contaminants'1-Filtration Electrolysis US Pat. No. 3. js3. Disclosed in OXS issue details
ing. In such a method, at the cathode of the SR tank nickel and hydrogen are produced, and at the anode cobalt, iron, arsenic and lead impurities are removed.a) Reagents/1. ) Elemental chlorine is formed in situj 7. :). Cobalt, iron, arsenic and lead precipitation is time dependent (1
-imc-dependent) reaction, and the precipitate is generally collected in a re-tension tank that follows the treatment of the electrolyte in an electrolytic cell. The precipitate can be removed using conventional techniques, such as v-slubrication, and used to deposit F# electrolytic purity nickel. 1 disclosed in the special WP mentioned above.
1. Cultural electrolytic methods can simultaneously and effectively remove iron, lead, arsenic and cobalt, yet do not require the tedious steps required by chemical methods to remove such contaminants. This is an improvement in technology in that it does not require In addition, on-site generation of C12 makes it easier to handle and manage reagents, eliminating the need for equipment that handles chlorine gas, and reducing the cost of on-site chlorine compared to liquid chlorine currently used in chemical purification. lower than cost. By proper management, i.e., adjusting the anode current density to generate as much chlorine as necessary to oxidize undesirable impurities, it is possible to prevent contamination based on excess chlorine. Reagent savings can be ensured.Furthermore, since the in-situ generated chlorine is completely converted to chloride ions, no chloride ion imbalance occurs in the electrolyte.

Advantageous 1. The process of the present invention, which also involves in-situ generation of chlorine, further improves on the electrorefining process described above in that the precipitation can be carried out at lower temperatures with lower energy requirements and more efficient nickel recovery. It is something. The cathode can be operated at low current densities, so that bath voltage and power consumption can be reduced. In addition, the electrolytic bath does not substantially produce nickel plating on the cathode (
As a result of operation, horse generation and N;10II generation can be effectively carried out in the cathode chamber.

The present invention provides at least one @electrode, at least one cathode, and substantially copper-free and free of nickel, alkali metal and chloride ions and dissolved impurities of cobalt, iron, arsenic (if iron is present) and lead. iM consisting of one electrolytic cell containing an aqueous acidic electrolyte
said impurity-free (
Also refers to the anode chamber and cathode chamber in electrolytic methods that purify nickel-containing solutions by removing nickel.

The two chambers are separated by a chlorine-resistant diaphragm installed in the front tank and acting as a medium for electrolytic contact between the anode and cathode chambers; the electrolyte flows into the anode chamber; the non-circulating catholyte flows into the cathode chamber. At this time, the catholyte should be set to 5 to prevent nickel ions from migrating to the cathode chamber under operating conditions, and the catholyte should be kept at
2 (only the decomposition of water and the generation of hydrogen occur)
Enough to make it 7. X) with an I aqueous aqueous solution containing CI-droxyl ions: ``fLj: Air flow to the front tank γ
It, then 1(,mu:(=') is generated at the anode, and at this time, the generated chlorine in the aqueous electrolyte is 1;t, ``+iI, p'
,'(Small l'(') reacts with a type of impurity in a liquid (g<'T'+1-); I N+'.

Separation from the phase liquid - (ro, thing) t!rP and - (ru "II
, bu v Cl) knee t-, li"+ro.

The operation of the method relies on the in situ generation of asthma resulting from −11+, σ) chloride in the phase solution. If chlorine is 1j, the result of the previous step and 141 of Kozue Refinery. A typical IL decoppered nickel refining electrolyte is Ingredients (containing 1 to obtain: Ni"' = 40- 80 Co" =
0.05-5Na+=1.0-50 A
s""= 0.001-2 ('f-jko&workAs-
'-'')CI-=15-90 Pb++=
0-000.1-0.01So 4==2
i 5o C17""-':: 0.001
．． - 09U11131303= 5-20 I"
e = 0.01-1 typically p of an impure electrolyte
H is about 2.5 to about 5.2. Of course, the composition of the electrolyte will vary depending on the ore and how the ore is processed. The electrolyte is 1n, the anolyte component of the pre-cell, and therefore the components of the electrolyte, apart from the chloride ions and nickel refining electrolyte, are chosen to satisfy the electrical and chemical requirements of the device. (1) The desired concentration of essential components in the solution depends on the function of each component. p)-1 of the impure electrolyte raw material is
It should be about 3.8 to 5.2, and if necessary nickel carbonate or other suitable 7. It can be adjusted with C base. The nickel ion concentration must not exceed its maximum solubility in the electrolyte.

The alkali metal level must be sufficient to ensure conductivity of the electrolyte. It is necessary that chlorine ions exist, and moreover, 1. CI2
It is necessary that there be enough 112 papers for this to occur. The parameters of the system can be designed such that the amount of chlorine generated does not substantially exceed the violet required for oxidation. Typically at least 5VA, preferably 15VA
j, 2 (19', //, f, - Exceeding 1,000 k) chlorine ions must be present in the electrolyte. Chlorine ions can be filtered by adding alkali gold (commonly used sodium chloride or potassium chloride). Sodium chloride is preferable because it has a value of 111. [Another gold standard 11 minutes], chloride J, effect and l
-1- Even if it exists and exists. The use of halides other than chloride θ) is a feature of the present invention: ii7. Surroundings
(, ”, C') Idiot - It's not funny. Therefore, the description of the tree is out.

1 for the current JJ, i generation of 1 molecule from chloride ions in the layer liquid
This can be explained as follows.

Because of the impure nickle-containing f'4 swamp supplied to the anode chamber (l,
- For nickel refining 1b', layer liquid) is 1) mixed 1) liquid agglomerate formation -4.

The invention? The feature of the 1jll'l tank is that the anolyte is essentially separated from the anolyte to bring it into an essentially steady state (1,
4. It is possible to do this. When operating the frost and ys tank, the 1 water 5+, iono d, υ・'norkali metal ions are moved to the anode chamber or L') to the stern, and are used for reaction with hydroxyl ions, and the t names A1 and Alkali metal hydroxide Zuro Kaoru. Water undergoes cathodic decomposition II
Releases 2. The remaining hydroxyl ions are utilized by the mobile hydrogen and alkali metal ions.

At the cathode, m1 is emitted as described above. The catholyte is preferably separated from the anolyte as an alkaline aqueous solution containing at least 0.5 moles of hydroxyl ions. For example, the sodium hydroxide level is about 20f,
or 40-200 f/I, for example about 150 f/I. Under alkaline conditions in the cathode compartment, nickel does not substantially migrate into the cathode compartment. To prevent alkali hydroxide build-up in the catholyte chamber, a hydrostatic head is maintained in the catholyte and water flow into the catholyte is directed through a diaphragm.
A positive flow from the catholyte to the catholyte should be maintained through the anolyte (at a set pressure). In this way, the catholyte is essentially maintained at a steady state. (as a result) I2 is released at the cathode, with essentially no nickel plating at the cathode and essentially no nickel precipitation in the alkaline catholyte.

The electrodes need to be made of a phase f1 that is a good conductor and resistive to the respective environment. The electrodes can take any suitable form for the electrolytic cell, e.g.
It can be made with metal, rods, tubes, gold <ti, ~exband metal, etc.

The base material of the electrode has a more conductive core and a surface material Tt.
It is possible to do tl;) with the one provided. The anode is insoluble and suitable for C12 loading.1. c An arbitrary σ month What month is the anode?

For example, a graphite anode or a dimensionally stable anode can be used. For example, it is well known to use platinum group metal anodes or platinum base metal arcs and/or platinum group metal oxides.
M+t ゛Alkaline material such as steel, stainless steel,
or nickel. Anode and I'@
The distance between him and Yotsuya is limited and 1. I thought it would be 1, but then a short circuit occurred between the electrode and the diaphragm 7. It is necessary to arrange it so that the

The diaphragm that separates the electrolyte and catholyte must be a material that is resistant to the reactants and products on both sides of the cell and has low electrical resistance. Presence of chloride (
- Since chlorine is generated in the electrolytic cell, the diaphragm is resistant to chloride and chlorine, especially baking soda, and this property is referred to here as a chlorine-resistant material. Other characteristics of the diaphragm are its permeability and physical strength. Generally, chlorine,
Types 1 and 2 used in electrolytic cells for IJ construction σ) Diaphragm 4' - even oversized 2). Suitable examples include asbestos and fluorinated hydrocarbons, such as polytetrafluoroethylene (modified for wettability).

Other suitable 1. C substance (coated with a suitable composite material 1-
By doing so, it can be made salt water resistant. Kotonto 1.
The analogy for c-substance is Rikifuchikaron 1 (Kinbuchi Chemical Industry Co., Ltd.)
(product of Union Carbide Co., Ltd.), and Dynel (1) Y-NEL) (product of Union Carbide Company, USA).

The electrolytic cell typically has a power rating of about 200 amps per square meter (
ASM) and is operated at an anode current density of about 100-500 A, SM. 11.4 degrees of the electrolytic cell is maintained at 50-70 degrees Celsius.

The flow iL of the electrolyte flowing through the anode a≦ is set to an appropriate value7. C constant'
The desired reaction will occur in the desired number of electrolytic cells in a torrent flow5.
The dark season is 2. The number of vessels is governed in part by the system V being designed. Thickness of the method of the present invention 7. c The advantage is that the electrolytic refining of nickel electrolytes can be carried out with lower power consumption, e.g. less (up to 30% less) than would be required in the case of a membraneless tank.Other advantages , the method of the present invention is suitable for m of less than 5 V, e.g.
This means that it can be operated using voltage. In addition to the low cost of M electrolyte solution, the recovery of cobalt from electrolyte solution is
(It can also be done with a power supply with considerable savings)
. As mentioned by Mif, U.S. Patent No. 3,983,018
The diaphragmless electrode described in the specification is an improvement over the non-electrolytic method of the prior art, and the method of the present invention does not significantly improve the electrolytic system4).

The method of the present invention is illustrated in the drawings.

In the drawing sheet G shown in Fig. 2, 1i (blow chamber 1 = 1 and cathode chamber 15 are separated by 41N (41N) with chlorine-resistant diaphragm 1).
d! , shows the tank before opening tank 1. The tank shown in Figure 1 has an anode 13 made of graphite, for example, and two cathodes 12 made of stainless steel, which are used for CI2 blast generation.
With reference to the second v1, the analogy is that decopper removal l, - impurities i1i,' due to bonding with metallic nickel (not shown), for example, resulting from the melting of the crude nickel anode in the solution process (not shown) When the IW solution is supplied to the anode chamber 14 of the front tank 10, the composition of the electrolyte varies depending on the composition and previous location of the ore.
In the method of the present invention, nickel! 6 and impurities such as 1
In addition to iron and lead, the electrolyte contains alkali metal ions and chloride ions.

Preferably, the chloride ion content i)- is sufficient to give high CI2 efficiency at the anode. Sulfate ions are present in the previous process, and boric acid is a well-known additive to refining electrolytes.
9/A Nino'r le, 95? 7'Zhk salt, :3
5 fj7', e sodium, +6 y/-p boric acid, 3
5 Of course to fZ chloride and impurities 1. 0.1 Mutsumi cobalt, 0.05 ship; modified, 0. (,105VA (tit element and 11.002 tit lead)
Use J1i electrolyte. Impurity 'r1 (pH of dissolution is approximately 2.0 to 5.2. With addition of TTF flow, positive 1
Elemental chlorine generated in 1#13 begins to react with divalent cobalt ions in the anode chamber 14, and similarly begins to react with iron, arsenic, and lead ions in the electrolyte. Anolyte (not shown)
It is preferable to sparge air to improve speciation CI2 and contact of the base with the impurity to be oxidized L2 and redissolve the nickel hydroxide precipitated on the diaphragm. Contaminants such as cobalt, arsenic, and 1 (and the oxidation reaction that converts lead into cold hydroxides are produced in a time-dependent manner).The reactive anolyte is sent to a holding tank 16 where it undergoes an oxidation reaction and hydration. Decomposition takes place. The anolyte silicidation power is governed by the current density of the anode, the efficiency of the chlorine reaction, the size of the bath, and the residence time for the reaction (31E K).

In the cathode chamber 15, the anolyte, which is an aqueous medium containing sodium hydroxide, is a non-circulating electrolyte.

The initial NaOH content G', t1, is approximately 802 μ and 1
Sodium chloride content is approximately O ~ 40 pi t) Li 4+
2+ o In the cathode chamber, water is added and the anolyte is released through the diaphragm to increase the release rate of the anolyte through the diaphragm.
The level of sulfur and lithium hydroxide in Th 7ffl is about 80~
The hydrostatic head is maintained by establishing J'L rather than being maintained at 20 (1/A).

- In the grain pressure and holding tank, hydrolysis takes about 20 minutes to about 1 hour.
It typically lasts about 40 minutes. pH depending on desired selectivity
In order to maintain the desired value, alkaline substances in the sunset, such as N + COa, are added to the electrolyte (
That is, it is added to the anolyte (anolyte supplied from the anode chamber). The oxidized electrolyte is conveyed by a bonder or by gravity to a filter 17 in which the formed cobalt, iron, arsenic and lead precipitates are removed from the liquid. The purified electrolyte can be returned to the refining circuit or, if necessary, passed through one or more additional purification steps to further reduce the impurity content.

Under the influence of the applied current, chlorine is generated at the anode 13 and the cathode 1
I2 occurs at 2. Generally, impurities are oxidized and precipitated by hydrolysis. C in electrolyte and holding tank
The overall simplified reaction for o"+ can be expressed as: CI.+2Co"+3NiC
03+ 3H20→2Co(OH) 3+3Ni ++
+2CI −+3C02 Other reactions such as the oxidation of N i +++ of N jC03 are difficult to prevent. Iron behaves similarly to cobalt, and arsenic and lead precipitate with iron.

Oxidation of electrolyte)17. Carefully monitor the level and pH.
II, it is possible to selectively precipitate undesirable elements. In this way, for example, a purer cobalt deposit can be obtained. The selection process, which can advantageously be carried out in a holding tank, involves two stages. 1st
At step 1, the electrolyte is partially oxidized to a pH slightly lower than that required for cobalt precipitation but high enough for iron, arsenic and lead precipitation, e.g. about 3.5 to 4.0.
HK adjusted. After removing the arsenic, arsenic and lead precipitates by p-filtration, the electrolyte is fully oxidized in an electrolytic cell in the second stage.
The pH of the holding tank is increased sufficiently to precipitate cobalt, for example about 4.3 to 4.8. Alternatively, or in combination with a holding tank, the number of electrolyzers and the anolyte flow rate can be adjusted such that the rf fluid (anolyte) exits the electrolytic system at a given current density, fa 19 rf fluid (anolyte) at the desired p I-T. You can.

To enable those skilled in the art to further understand the invention, the following examples are provided.

Wataru In this example test, a CI2 generation tank with a diaphragm was used as described in U.S. Pat.
, 983.081, 2 and 3.
Compare the non-diaphragm tanks used to obtain the data.

In the tests shown in this patent, the small pure electrolyte used was from a decoppering tankhouse (tankhouse) from a nickel smelter.
housel $J'ltl'N, about 4 (+ -80
pl-=kkel, about 33-451 sodium, about 46-
56su chloride, about 100-150! Sulfate, 33-I
It contains less than 0.01 rods of dissolved copper and has a p I-1 of 2.9. Fit, the melting tank has a stainless steel pan net cathode with a diameter of 2.4 mm and a length of 6.4 cm, and a 1.3 cm x 6.4 cm x
Equipped with S-N-Cl graphite anode. The temperature of the electrolytic solution and the holding tank are controlled at 54 DEG C. When it comes out of the electrolytic tank, the oxidizing power of the bath solution is equivalent to 0.290q equative.

Comparative tests conducted according to the method of the present invention were substantially the same as the tests described above, except that the anolyte (uncleaned lambda base liquid raw material) and catholyte were separated by a Kaneka IJ diaphragm. . The cathode chamber contains 20 V7 NaOH. Pump water into the cathode bag to maintain the head at l cm.

The general conditions under which the comparative experiments were conducted are shown in the table below, and the analysis of impurities in the 1-0 raw material and effluent is also shown in the table.

The table shows '1- According to the comparison results, the same electrolytic refining 'tT;
i, Solution) For the purification of iv, the electrolytic cell of the present invention requires I.
The power consumption needle is approximately 100% for a CI2 generation tank without a diaphragm.
It turns out that it is nothing more than a dedication.

Although the invention has been described in connection with preferred embodiments,
It goes without saying that modifications and variations may be made that depart from the spirit and scope of the invention as will be readily apparent to those skilled in the art. It is also contemplated that such modifications and variations fall within the scope of the present invention.

/ 7/ 1-cho-bi-kyoku ：・、・to・・・・１゜ 2//' /′ , /’

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a diaphragm electrolytic cell according to the present invention; FIG. 1A is an isometric view; FIG. It is a flow sheet of the polishing process. io... Electrolytic cell, 11... Diaphragm, 12
...Cathode, 13...Anode, 14...
...Anode chamber, 15...Cathode chamber. Applicant's agent Kiyoshi Inomata (A)
(B) also 1 closed b 2 figure

Claims (1)

[Claims] 1. Low (with one anode, at least one cathode and substantially copper-free and nickel, alkali metal and chloride ions and cobalt, iron, arsenic (if iron is present) and lead) forming an electrolysis device consisting of at least one electrolytic cell having an aqueous electrolyte containing dissolved impurities; In an electrolytic method for purifying a containing solution, an anode chamber and a cathode chamber are provided in an electrolytic cell, and the two chambers are separated by a chlorine-resistant diaphragm that serves as a medium for electrolytic contact between the anode chamber and the cathode chamber; Flowing electrolyte #: into the anode chamber; maintaining a non-circulating catholyte in the cathode chamber, where said catholyte is prevented from migrating nickel ions to the cathode chamber under operating conditions and substantially free of water in the cathode chamber. an aqueous solution containing sufficient 7.C hydroxyl ions such that only decomposition and hydrogen evolution occur and means are established to prevent transfer of nickel ions from the electrolyte to the catholyte; an electric current is applied to the electrolytic cell; At this time, the chlorine in the aqueous electrolyte reacts with one type of impurity to form an impurity-containing precipitate; 2. The method of Claims JsA, wherein the concentration of hydroxyl ions in the catholyte is at least about 0.5 M. 3. The anode The method of claim 1, wherein the electrolyte in the chamber is maintained at a pHrL of up to about 5. 4. A method as claimed in claim 1, wherein means are provided for channeling cathodic flow into the electrolyte through a diaphragm. 5. The reactive electrolyte is sent to a holding tank to undergo hydrolysis of impurities, and the pt-t of the holding tank is adjusted to a value consistent with the desired precipitation due to hydrolysis of impurities. 71°, the method according to claim 1. 6. The p f of the electrolyte in the holding tank is approximately; 3.5 to 4.0σ)
6. A method according to claim 5, wherein the value is adjusted to 1. 7. In the holding tank: The pal of the base liquid has a precipitated width of about 4.
3 to 4.8 R cycle 1), and its pl1 is Kono;
Adjusted for the precipitation of the root, the special
The method described in section 5. 8. The method according to claim 1, wherein the electrolytic refining vessel is operated at an anodic current density of about 100 to 500 ASM. 9. Nickel refining, in which the electrolyte is operated at a temperature of about 1) to 70°C. 11. The method of claim 1, wherein the process is from a new process and the electrorefining steps are operated at substantially the same temperature. 10. The concentration of chlorine ions in the electrolyte is low (approximately 5
The method according to claim 1, wherein y/I. 11. The chlorine content in the electrolyte is at least about tri 9/
2. A method according to claim 1, wherein the temperature is maintained at l/. 12. The method described in the first column, in which the shortfall in the chloride level of the base solution is removed by NaCI. 1, :(-1t54j(Y solution is an aqueous solution of alkali metal hydroxide, and the initial ~C water 1'l chloride or about 2 pieces.-
Approximately zIJ(11+'/, 11σ)NXIol 1 It
The method described in section I11α, Section Jc'l of the request for this (11 per 1-L4>, l11°r permission request. Then, the catholyte is released into the electrolyte at a rate that maintains the hydroxide level in the electrolyte 71 from about 40 to about 200 Vf.
The method described in ``Range of search iJ'''. [5, ``Id, force reduction lLt+G is comparable but without a diaphragm (' = J 'f less than the comparative method using
The method described in section. Ib, 'tl IQ〒l! 2. A method according to claim 1, which can be operated with a bath voltage of less than 5.5 cm. Enlargement: One anode, one cathode and one cathode with an aqueous acidic electrolyte substantially free of copper and containing dissolved nickel, cobalt, alkali metals and chloride ions. - forming a decomposable device consisting of an electrolytic cell containing cobalt and one or more elements selected from the group consisting of iron, arsenic (if iron is present) and lead; In an electrolytic method for producing 1!i# of a nickel-containing solution that may contain impurities of -1-, an anode chamber and a cathode chamber are provided in an electrolytic cell, and a A chlorinated diaphragm separates the two chambers; an electrolyte is flowed into the anode chamber, and a non-circulating catholyte is maintained in the cathode chamber, with the catholyte being hydrated at about 200 f/Z. Contains sodium only
The catholyte under operating conditions produces essentially only hydrogen at the cathode and hydroxyl ions in solution, and the concentration of hydroxyl ions in the catholyte prevents nickel ions from migrating from the catholyte to the anolyte. A positive water pressure is maintained in the catholyte to release the catholyte into the electrolyte; an electric current is applied to the electrolytic cell to generate chlorine at the anode, and the chlorine in the aqueous electrolyte is cobalt. and iron (if present)
), reacts with arsenic and lead; removes the reactive electrolyte from the anode chamber and sends it to a storage tank where it hydrolyzes cobalt and other impurities (if any); An electrolytic method characterized in that -1 is adjusted to a value corresponding to the precipitation of introduced metals. 18. The pH of the electrolyte in the holding tank is iron, arsenic and lead (
I) II or about 4.3 to 4.0 is maintained at about 3.5 to 4.0 for precipitation of I) II or about 4.3 to 4.0.
18. The method of claim 17, wherein the cobalt is precipitated and recovered from the purified electrolyte. 19. One electrolytic cell and at least one holding tank, where the 11L decomposition cell has an anode chamber and a cathode chamber, and the anode chamber and the cathode chamber have an electrolytic contact between these two chambers. The medium is separated by a chlorine-resistant diaphragm; nickel refining 1v. The base liquid is supplied to the anode chamber and can be written as nil, and the liquid is sent from the anode chamber to the holding tank; the catholyte is sent to the cathode chamber. A device for supplying water; a device for maintaining water under positive pressure and introducing it into the catholyte and discharging the catholyte into the CFJ'l solution through a diaphragm; and a device for applying an electric current to the electrolytic cell. The correct device Δ for layer liquid purification is shown at t.