HU209828B - Method and apparatous for deposition of metal ions from low metal ion contant waste waters - Google Patents

Abstract

Metallic ions esp. of the bi-valent type are removed from rinse water with a low concn. of such ions. The concn. of other ions, such as hydrogen is maintained constant. (Dwg.No.0/1)

Description

BACKGROUND OF THE INVENTION The present invention relates to a process and apparatus for the removal of metal ions from small, particularly divalent, metal ion-containing flushes.

Wastewater with low concentrations of metal ions is mainly produced by the surface treatment of metals, for example, when metal parts containing galvanized or nickel-plated solution are rinsed with adhering metal-ionic solution, which enters the rinse water. Rinse waters must be purged of toxic metal ions before they are discharged, for which various methods have been developed.

By neutralization, metal ions in the form of hydroxide can be mostly - deposited; most commonly use this method to remove them. However, neutralization of large volumes of dilute solution is not economical and is therefore concentrated in advance. In one of the most common solutions for this purpose, the rinse water is passed through an ion exchanger, which binds the cations, which can then be used again for rinsing. The disadvantage of this method is that wastewater is produced in two places, on the one hand a stationary water rinse must be installed before the ion exchange rinse, otherwise an excessively concentrated solution would reach the ion exchanger. The concentration of metal ions in this standing water rinse is constantly increasing. After a certain limit, this should be replaced with clean water. On the other hand, a solution with a higher concentration of metal ions is also produced during the regeneration of the ion exchanger.

Wastewater, for example, can be purged of metal ions by neutralizing said solutions. The disadvantage of this method is, inter alia, that metal ions are recovered in the form of hydroxides which are difficult to utilize and that both elution and neutralization require chemicals that subsequently increase the salinity of the waste water.

Two methods have been developed for the removal of metal ions from rinse water by electrolysis, depending on whether sewage treatment or metal recovery was the primary goal. In the first case, at least 99% of the metal ion must be removed from the flushing water. In the second case, removable metal ions remain in the waste water; the process is economical by the amount of recovered metal.

Removal of the above-mentioned almost total amount of metal ions from the rinse water by electrolysis poses considerable difficulties, primarily because the concentration of the metal precipitated must be low and allows only a low diffusion flow rate. Since the metal removal rate cannot be higher, if a larger amount of metal is to be deposited per unit time, i.e. working at high current, either the cathode surface or the diffusion limit current must be increased.

However, extending the surface in a conventional manner is only reasonable up to a certain limit because the size of the equipment will soon be too large. The solution is called the so-called. three-dimensional electrodes where, for example, floating metal or graphite particles form the cathode. (For example, U.S. Patent Nos. 3,523,573, 2,622,497, 1,956,457, U.S. Patent Nos. 4,244,795, 4,240,886, British Patent Nos. 2,048,300, and 2,084,195) .

In addition to material quality, concentration and temperature, the diffusion boundary current depends on the relative velocity difference between the liquid and the metal surface. Satisfactory results cannot be achieved by mere mixing, and various methods have been developed for turbulent flow of liquid at a rate of at least 1 m / s (e.g., German Federal Nos. 2,719,667, 2,054,649, 2,058,134, and 2,125,825). and, more recently, flow through carbon fiber electrodes which provide a large surface area allows for higher currents (e.g., British Patent Nos. 2,038,867 and 4,396,474).

The main disadvantage of this method is that in most cases, such a low concentration solution does not succeed in recovering the metal in a form that can be used directly. The metal has to be subsequently dissolved in acid or anodized and again the rinse water is concentrated. (U.S. Pat. Nos. 178,964, U.S. Pat. No. 4,238,314, German Patent No. 2,232,903, 2,027,452, and British Patent No. 2,025,461). The result of the process is also questionable, since most surface treatment plants produce valuable or non-cathodic metal ions (iron, aluminum, chromium ions), which are usually removed from wastewater by neutralization, so conventional wastewater treatment cannot be omitted.

When the goal is to recover the precious metal, they are content to remove 80-95% of the metal ions. Then they follow the path that after the metal separation bath a so-called and a regular flush with running water. Initially, clean water is added to the flush, and then, when flushed, the metal ion concentration reaches 20-5% of the electroplating concentration (depending on the intended recovery rate), then the electrolysis solution is continuously electrolysed at exactly the same amount of metal ions. is flushed during rinsing. The resulting workpiece carries only 20-5% of the original metal ion, which still needs to be rinsed, but this rinse water has significantly less volume and impurities than the conventional process. The electrolysis of the economy rinse can be carried out under significantly more favorable conditions than the said "near" total metal recovery, since the metal ion concentration of the solution is at least one order of magnitude higher and thus the metal can be utilized in an appropriate arrangement.

By adjusting the current, the metal ion concentration in the flushing rinse can be kept constant, but the other parameters of the solution would have to remain unchanged for even metal removal. The biggest difficulty is the change in pH. At the cathode, the metal is mostly deposited, while at the anode, most of the hydroxide ions undergo oxygenation, and thus the solution is rapidly acidified, resulting in hydrogen release at the cathode as opposed to metal. Another difficulty is that

At the anode anode, within the oxygen-release potential range, a large part of the organic additives used for metal removal are oxidized and thus the quality of the metal is reduced. The process is disadvantageous for solutions which cause corrosion of standard anodes. Many galvanic solutions contain halide ions, primarily chloride ions, which, in addition to anode corrosion, increase the difficulty with the formation of toxic gases at the anode.

In addition to electrolysis, electrodialysis can also be used to recover metal ions from dilute rinse water. In this process, membranes are used that allow either cations only or only anions to pass (cation exchange or anion exchange membranes). Dozens of cells, sometimes hundreds of membranes, can be formed to concentrate on current in every second cell portion, diluting the solution in the interstices (such as silver recovery in U.S. Patent No. 3,022,305). When the rinsing waters are introduced into the diluting cell portions and thereby concentrate the original galvanic solution introduced into the second cell, the metal ions deposited with the workpieces are substantially returned. The process is quite affordable, both because of the cost of many membranes and because of the large amount of energy used due to the high electrical resistance of the cell. The problem is that there is no need for the metal ion to be completely removed in the galvanic solution, because generally the anodic current utilization exceeds the cathodic one, so more metal is soluble than it is deposited (cathode also develops hydrogen). In this way, some of the metal ions are again in a concentrated solution which is difficult to recover.

A disadvantage of the devices and devices known so far is that they are very complicated, since in these devices, cells with hundreds of membranes are formed and the solution is concentrated in every second membrane space. Such a device is described e.g. No. 30 22 305 There is also a patent in the Federal Republic of Germany, which primarily allows silver recovery.

Our aim was to develop a solution for cathodically separating metal ions from small, especially divalent metal ion-containing rinses, in such a way that the above mentioned disadvantages do not occur and that the metal ions develop in high purity, compact metal, efficiently, without toxic can be detached.

In our experiments, it has surprisingly been found that the above object can be achieved by keeping the concentration of other components, in particular hydrogen, in the said rinse water, in addition to the metal ion or metal ions to be separated.

During the electrolysis of the purifier, a significant amount of acidification occurs due to the anodic oxygen evolution and some alkalization due to the evolution of hydrogen as a cathodic side reaction. In addition, the concentration of the solution is increased by the chemicals transferred from the electroplating solution to the workpieces, while the chemicals transferred to the next rinse solution are reduced. In practice, electroplating solutions are generally more concentrated than the economy rinse, so the material entrained therein is generally more than applied. The concentration of the metal ions is kept constant by subtracting the difference between the amount introduced and the amount deposited in the form of metal by electrolysis. By adjusting the concentration of all materials other than the metal ions in the savings rinse to be the same as the galvanizing solution, it is ensured that, except for the metal ions, all materials have the same loading as the application, so that the concentration of the solution does not change.

The above statement - without any additions - applies only to chemicals that do not react on the electrode. The hydroxide ions are consumed in substantially the same amount as the metal ions. Practical experience has shown that if the solution is provided under conditions such that the molar concentration of hydrogen or hydroxide ions exceeds the metal ion concentration, the pH change due to oxygen evolution is negligible and the pH of the flushing rinse does not differ by 0.5 At pH ρΗ of the electroplating solution, metal removal can be achieved continuously with good results.

Electroplating is in many cases carried out in slightly acidic solutions close to neutral. In such cases, the hydrogen ion concentration is several orders of magnitude lower than the metal ion concentration, so the above-mentioned method is not applicable, and the pH will decrease rapidly during economy electrolysis. Experience has shown that eg. in a 500 l rinse, a pH change of one unit occurs with a charge of 10-30 Ah. In such cases, it is preferable for the present invention to consistently measure the pH with a glass electrode and to provide the alkaline dosing (acid addition in the case of an over-alkalization) with a pH-controlled control system.

Addition of chemicals has the disadvantage that anions or cations remain in solution after the hydrogen ions or hydroxide ions have reacted at the cathode or at the anode. These ions are continuously enriched in the process of saving electrolysis, so it is important to try to incorporate ions that do not interfere with the metal separation, or they are also present in the electroplating solution. Thus, for example, in the case of zinc recovery, the addition of ammonium or potassium hydroxide rather than sodium. Providing that the concentration of ammonium or potassium chloride in the water purifier is the same as that of the electroplating solution, the concentrations can be kept constant to within ± 20% with the addition of ammonium or potassium hydroxide as in the previous method.

We have seen above that the rapid change in pH is due to the depletion of hydroxide ions at the anode. If the anode space is separated, this effect can be eliminated. Any material which does not impede ionic current transfer is suitable for separation.

HU 209 828 Β

Preferably, the cathode space of the electrolysis electrolysis, where there is a solution for rinsing, is separated from the anode space by an anion exchange membrane, and it is ensured that while the anions conduct current in the membrane, the hydrogen ions remaining there

The ion exchange membrane can also be advantageously used to prevent anode corrosion and anodic development of pollutant gases (such as chlorine gas). In this case, the anions of the economy rinse must be kept away from the anode, so a cation exchange membrane is required. In this case, hydrogen ions can easily pass from the anode space to the flush, so some other method as mentioned above should be used to keep the pH of the solution constant. These may include the use of an anion exchange membrane. The anode and cathode spaces are then separated by two membranes and a so-called "diaphragm" is formed between the two membranes. middle space too. The electrolysis cell is thus divided into three spaces. In the anode space, which contains any electrolyte solution which is well conductive, preferably free of halogen ions, oxygen is generated and the resulting acidification can be compensated by addition of alkali and / or occasionally by solution exchange. For example, there should be a cation exchange membrane between the anode and the center space. The current is transported through the conductive cations of the conductor salt placed in the anode space. In this way, the anions in the central space cannot get near the anode, so there is no risk of anode corrosion or the development of toxic gases. Between the center and the cathode space, an anion exchange membrane is passed through which the anion exchange flushing anions carry current, preventing any cation, especially the hydrogen ion, from entering the space flushing cathode space.

In the case of metal removal from a low metal ion concentration solution of the economiser, the cathodic current utilization, especially at higher current densities, is less than 100%, which means that even less metal is liberated in addition to the metal. Hydrogen evolution occurs through the neutralization of hydrogen ions, thus increasing the pH in the cathode space. In this case, it is expedient to provide a second circuit in the cathode space, at the cathode thereof

which is preferably identical to the cathode of the first circuit

- metal detachment, anode undergoes oxygen evolution. The current in this second circuit is adjusted so that the oxygen produced at its anode consumes just as many hydroxide ions as the hydrogen ions at the cathodes are consumed while metal is being removed. As previously mentioned, in some cases it is not advantageous to place an anode in the solution of the fabric softener. In this case, the anode of this second circuit is also separated from the cathode space, preferably by an ion exchange membrane, while ensuring that the current between the two spaces is conducted only by hydrogen or hydroxide ions. This is achieved, for example, by adding a solution of sulfuric acid to the anode space of the second circuit, the hydrogen ions of which pass through a cation exchange membrane to compensate for the alkalization of the cathode space.

The economiser retains a significant portion of the metal ion removed from the electroplating solution, typically in the range of 80 to 90% in commercial practice, and can be recovered electrochemically from the metal by the process of the invention as detailed above. However, the workpiece removed from the purge still contains a solution contaminated with metal ions (10-20% of the metal ions are lost here). This solution is usually rinsed with running water and the rinsing water enters the sewage treatment plant. Some processes pass the rinse water through an ion exchange column, the eluate of which contains metal ions in a concentrated solution, so that their processing, for example in the form of metal hydroxide, is more economical.

In our experiments, it has been found that this eluate, after a possible pH adjustment, can be used to increase the concentration of both the original electroplating solution and the flushing rinse, and thus the total amount of metal ions discharged can be directly traced back to the electroplating process.

It is a further object of the present invention to provide a device which eliminates the disadvantages of the prior art devices and equipment and ensures a sufficient amount of metal to be recovered in a simple construction.

The object of the present invention is achieved by a device having a plurality of at least two electrolyser spaces at the free end, separated by an ion exchanger, having at least one end plate having a lower orifice and an upper orifice (s) and submerged electrodes.

A preferred embodiment of the device according to the invention has a membrane space filled with an ion exchange resin.

Another preferred embodiment of the device according to the invention is formed from a support frame with a window and an insert fixed to the window of the support frame with a fastening frame, wherein there is a releasable joint, preferably a screw connection, between the support frame and the fastening frame.

In a further preferred embodiment of the device according to the invention, the insert is formed of a plate with holes and a replaceable membrane formed in the form of a plug which closes the holes.

In a preferred embodiment of the device according to the invention, the electrolyzer space (s) is also provided with a laminar flow stirrer.

In another preferred embodiment of the device according to the invention, the inlet of the electrolysis spaces is also provided with a distributor head.

A further preferred embodiment of the device according to the invention has a U-shaped electrolyzer space (s).

An exemplary embodiment of the device according to the invention will be described in detail with reference to the accompanying drawings, in which:

Figure 1 is an exploded view of the device of the invention, a

Figure 2 is a membrane space of the device of Figure 1, a

Figure 3 is a sectional view of the membrane space of Figure 2, a

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Figure 4 is a sectional view of another embodiment of the membrane space of the device of the present invention

Figure 5 is a further embodiment of the membrane space of the device according to the invention, a

Figure 6 is a sectional view of the membrane space of the device of Figure 5.

Figure 1 is an exploded view of a preferred embodiment of the device of the invention. The apparatus of Fig. 1 comprises essentially two electrolysis spaces, which are separated by cells 3 and 2, respectively. The insert 3 consists essentially of a support frame 8 with a window 13 and a membrane 4 fixed in the window 13. The free end of the electrolysis chamber 2 is bounded by a closing plate 1. The electrolysis space 5 is delimited by the insert 3 and a closing plate.

However, it is to be noted that the number of electrolysis spaces provided in the apparatus may be varied as desired. In this case e.g. the insert 5 is closed on each side by an insert 3.

The electrolysis spaces 2 and 5 are provided with an inlet 7 and an outlet 6.

Electrodes 2 and 5 are immersed in electrodes (not shown).

The lower inlet is also provided with a manifold not shown here.

Experimental experience has shown that the efficiency of the device can be increased by the addition of laminar flow baffles in the electrolysis chamber.

Figure 2 illustrates the insert of Figure 1 consisting of a support frame 8 with a window 13. The membrane 4 is located in the window 13 of the frame 8.

The fixing of the membrane 4 in the support frame 8 is illustrated in Figure 3. The diaphragm 4 is secured to the support frame 8 by means of a mounting frame 12, whereby a releasable connection is provided between the support frame 8 and the mounting frame 12 by means of a screw connection.

Figure 4 is a sectional view illustrating another preferred embodiment of the insert 3 used in the device of the invention. In this embodiment, the insert 3 consists essentially of a plate with holes 9, in which the plug-shaped membranes 14 are disposed in the holes. In this embodiment, the membranes are easy to replace with such a design and do not require replacement of all membranes at once, only replacement of an already worn membrane is required.

Figure 5 is a schematic diagram of a further embodiment of the device according to the invention. In this solution, the electrolysis spaces 2 are spaces enclosed by sealing plates and are not in direct contact with the insert 3 separating them. The electrolysis spaces 2 are connected to each other by means of a shut-off assembly 10.

Of course, such a design also has a different insert design. In the present embodiment, the insert is provided with a resin layer 11.

The operation of an exemplary embodiment of the device according to the invention will be described with reference to Figure 1 below:

The fluid to be electrolyzed passes through an inlet 7 through a distribution head (not shown) to the electrolysis chamber 2. The movement of the fluid is preferably provided by a fluid pump. The electrolysis space 2 is divided into cells with membranes 4 fixed in the insert 3.

In the cathode chamber, the cell of the electrolysis chamber 2 into which the cathode is immersed, the concentration of metal ions in the saving solution decreases and then discharges into the outlet 6 and the liquid flows back to the economy flusher, whereby a metal ion is deposited on the cathode.

The flow of fluid into the cathode space is performed continuously.

The anode space, the cell of the electrolysis chamber into which the anode is immersed, is not flowed, so the solution must be changed periodically.

The optimum operating parameters of the electrolysis spaces are provided by the sensor head of the submersible measurement unit itself and the metering device controlled by it.

Example 1

The bulk product was galvanized in a 20 L bath containing 20 g / l zinc ion, 110 g / l sodium hydroxide and 6 ml / l blends of benzaldehyde, epichlorohydrin and glycyl aldehyde as a polishing agent. The zinc ion content of the purifier will be 1.6 g / l and the alkaline content will be 15.2 g / l after 1 day (~ 8h) use. The purge solution was then circulated continuously through a 3 L electrolytic cell in which zinc was separated at a current of 8.4 A while galvanizing and the zinc and alkali contents of the solution were measured.

operating hours h 0 7 12 33 52 70 87 104 120 Zn ² g / l 1.60 1.71 1.66 1.58 1.63 1.68 1.59 1.65 1.64 NaOH g / L 15.2 28.3 37.2 76.9 97.3 98.6 96.9 99.0 97.8

Thus, 0.58 kg of zinc was recovered by electrolysis, which corresponds to a recovery of 84% of zinc.

Example 2

The galvanizing line for the lightweight, suspended load line containing 300 liters of tubs consists of 60 g / l zinc chloride, 180 g / l ammonium chloride and polishing additives. (6 ml / l mixture of sodium benzoate and benzolacetone). The subsequent rinse aid at the start of the experiment contained 4.8 g / l zinc ion, 45 mg / l iron ion, 0.08 mg / l nickel ion, 0.04 mg / l cadmium ion, and less than 0.02 mg / l lead ion. A small amount of hydrochloric acid was added to adjust the pH to 5.0. This economy rinse solution was circulated through an electrolysis cell, which was a 0.6 x 1 m by 0.6 m high tub. This was divided into two sections with 1 m long 0.5 m high ion exchange membranes. One was an MA-40 anion exchange membrane and the other was MK-40 cation exchange membrane. You have 5% sulfuric acid on both sides of the cation exchange membrane5

HU 209 828 Β, while the solution of the purifier was introduced into the third space next to the anion exchanger and the 0.55 m ² zinc cathode plate with a useful surface was placed there. No electrode was placed in the middle space, while a lead anode was placed in the other outer space.

After the economy rinse, a three-compartment countercurrent rinse was used, the water of which was circulated through a homemade column containing 5 l Varion KSM cation exchange resin. After 35 hours of operation, the ion exchange column was regenerated with dilute hydrochloric acid and the regenerate was introduced into a purge rinse. The significant decrease in pH was compensated by the addition of concentrated NH ₄ OH.

The electrolysis current was varied from 10 to 15 depending on the measured zinc ion content of the solution.

üzemi- do 0 7 13 21 27 35 41 46 54 61 current- strength 12 12 12 10 12 15 15 12 12 12 Zn ²⁺ g / l 4.7 4.8 4.6 4.4 4.8 5.5 5.0 4.8 4.8 4.7 pH 5.0 5.0 4.9 4.8 4.6 5.1 5.2 5.0 5.0 4.8

During the experiment, 0.76 kg of zinc was deposited on the cathode with a content of 99.96%, an iron content of 0.02% and a cadmium content of less than 0.02%. The zinc loss of the system was thus reduced to zero, meaning full recycling.

Example 3

Fastener solution of nickel plating series (nickel plating solution, composition: 310 g / l nickel sulfate, 50 g / l nickel chloride, 40 g / l boric acid, polishing additives) in a 100 l electrolytic cell via a 100 l electrolytic cell circulation using a 1.2 m ² carbon steel cathode and a platinum-plated titanium anode. The immersed composite glass electrode was connected to a pH meter control system composed of Radelkis elements that controlled the addition of 10% H ₂ SO ₄ and 10% NaOH to ensure a constant pH.

operating hours h 0 1 7 13 21 27 54 83 104 PH 6.3 4.8 4.9 5.0 5.0 4.7 4.9 4.8 4.6 N ² + g / l 9.3 9.2 9.2 9.2 9.2 9.2 9.1 9.2 9.3

Electrolysis was performed at 120A. 11.2 kg of nickel were deposited throughout the experiment.

Example 4

The economy rinse of the nickelization line shown in Example 3 was coupled to an electrolyzing cell such as that used in Example 2, but using the NAFION 423 cation exchange membrane instead of the MK-40 membrane. Here we used two circuits, that is, three electrodes. In the middle space the solution of the economy rinse was circulated, where the following metal ion concentrations were measured: nickel = 9.3 g / l, iron - 21 mg / l, chromium = 0.13 mg / l, cobalt less than 0.05 mg / l first In this space we placed the common cathode of the two circuits. 5% sulfuric acid and platinum titanium anode were added to the two extremes. A current of 110 A was passed through the anion exchange membrane and 10-15 A current needed to stabilize the pH using another source of power on the cation exchanger.

isemid he h 0 7 14 21 28 35 42 49 56 84 i ₂ a 12 12 10 10 12 12 12 12 10 11 Ni ²⁺ g / l 9.3 9.2 9.2 9.2 9.3 9.3 9.2 9.1 9.1 9.2 PH 4.6 4.6 4.6 4.7 4.9 4.9 4.8 4.6 4.6 4.8

The experiment yielded 8.9 kg of nickel (88% recovery) with a nickel content of 99.8%, an iron content of 0.07% and a cobalt content of less than 0.02%.

The invention has many advantages. This results in the production of a compact metal which is partly more valuable than a concentrated solution and partly at the source can be used directly as an anode in the galvanic bath, as opposed to the concentrated solution, which can usually only be returned to the galvanic bath.

- The purity of the recovered metal is high compared to other processes. Less noble metals, due to the low current densities used, are not present, and noble metals do not enter the solution from the galvanic anode. Anions, organic additives and mainly their decomposition products, which upon evaporation or many countercurrent so-called. they often concentrate in the galvanic solution and interfere with metal separation when using a non-wastewater rinse, in which case they cannot be returned to the galvanic process.

- It requires significantly less chemicals than the conventional or ion-exchange process, which results in, among other things, a reduction in the salinity of the waste water.

- Avoid anode corrosion, no need for extremely corrosion resistant anodes.

- The formation of dangerous, toxic gases, especially chlorine, at the anode can be avoided.

- Saving electrolysis can be achieved more efficiently because organic additives are not oxidized at the anode.

The present invention provides enormous environmental benefits.

Claims (15)

PATENT CLAIMS A process for the cathodic separation of metal ions from low purity bivalent metal ion-containing flushing water characterized in that said In addition to the metal ion or metal ions to be separated, the concentration of the other components, in particular the hydrogen concentration, is practically constant. 2. A process according to claim 1, wherein the sparing rinse water is electrolyzed in which the hydroxide or hydrogen ion concentration is greater than the molar concentration of the metal ions. 3. The process according to claim 1, wherein an acid or an alkali is added to stabilize the pH, preferably with a pH meter-coupled dosing system. The process of claim 1, wherein the anode and cathode spaces are separated to stabilize the pH. The process of claim 4, wherein the separation is accomplished by one or two ion exchange membranes. 6. A process for the cathodic separation of metal ions from low metal ion rinsing water by electrolysis from a constant composition rinse water, characterized in that the metal ions are removed from the rinse water of the after-treatment rinse with an ion exchanger and recycled to a galvanizing or recycling system. Apparatus for electrochemical recovery of metals, in particular from wastewater of low metal ion concentration, characterized in that a plurality of at least two membranes (4) separated from one another by a liner (3) and at least one end plate (1) ) and an electrolysis chamber (2, 5) provided with an upper outlet (s) (6) and electrodes immersed in the electrolysis chamber (2, 5). Device according to Claim 7, characterized in that it has a cartridge (3) filled with ion exchange resin (11). Apparatus according to claim 7 or 8, characterized in that the bounding plates (1) of the electrolysis spaces (2, 5) are filled with resin. Apparatus according to claim 7, characterized in that the insert (3) is formed by a diaphragm (4) made of a support frame (8) with a window (13) and a mounting frame (12) in the window (13) of the support frame (8). is designed. Device according to Claim 10, characterized in that there is a releasable connection, preferably a screw connection, between the support frame (8) and the fixing frame (12). Apparatus according to claim 7, characterized in that its insert (3) is formed of a plate with holes (9) and interchangeable diaphragms (14) which seal the holes (9). 13. A7-12. Device according to any one of claims 1 to 3, characterized in that its electrolysis space (s) (2, 5) is also provided with a laminar flow stirrer. 14. Device according to any one of claims 1 to 3, characterized in that the inlet (7) of the electrolyser (s) (2,5) is also provided with a distributor head. 15. Device according to any one of claims 1 to 3, characterized in that it has a U-shaped electrolysis space (s) (2, 5).