DD211129A1 - CIRCULAR PROCESS FOR COATING COPPER AND COPPER ALLOYS - Google Patents

Abstract

The invention relates to a method for pickling copper and copper alloys to produce oxide-free, metallically bright surfaces, with simultaneous recovery of the copper and regeneration of the pickle solution. The aim of the invention is a pickling process, which runs environmentally friendly and with high current efficiency. According to the invention, for pickling, a solution containing 0.15 to 1.0 mol / l of sodium and / or ammonium peroxydisulfate and 2 to 4 mol / l of sulfuric acid is brought into contact with the workpieces to be treated at temperatures of 20 to 50 ° C. and the exhausted pickling solutions, containing 0.1 to 0.5 mol / l copper sulfate and a residual content of 0.1 to 0.65 mol / L persulfates, first subjected to a cathodic treatment for the deposition of at least 60% of the copper and for the reduction of the persulfates, then by To enrich anodic treatment in a conventional manner with peroxide sulfate to the initial concentration. The surfaces obtainable by this process are the prerequisite for the use of copper and Kupferlegierungswerkstuecken in many industries.

Description

Circulation method for pickling copper and copper alloys

Field of application of the invention

The invention relates to a cyclic process for pickling copper and copper alloys with simultaneous recovery of the copper and regeneration of the pickling solution. This is to produce oxide-free, metallically bright surfaces, which is a prerequisite for the use of these materials in many industries, eg, in refrigeration, in plant and mechanical engineering.

Characteristic of the known technical solutions

Due to their special properties (electrical conductivity, thermal conductivity, chemical resistance), copper and copper alloys find a wide range of applications in industry. To improve the surface finish and the durability, special surface treatments are required ·

Common surface treatment methods are J.

- Mechanical processes, such as polishing with Al ^ CL suspensions or pastes, blasting with kikroglaskugeln or application of ultrasound in sulfuric acid baths.

- Use of cleaning and degreasing solutions such as organic solvents or alkaline cleaners, such. B ·

-5 ^ 011982 * 045689 ~

Caustic soda, carbonates, phosphates, silicates or surfactants.

non-oxidizing mordants such as sulfuric acid, Kaliumoyanid, SaIae of hydroxy or amino carboxylic acids, eg. Gluconates, "rartrate, citrate,

- oxidizing pickling agents such as sulfuric acid / nitric acid (yellow spirit), chromic acid, peroxo compounds (hydrogen peroxide, Caro's acid, perosodisulfates) mixed with sulfuric acid, ferric chloride / hydrochloric acid _? Iron sulphate / sulfuric acid or copper (II) chloride / hydrochloric acid ·

Anodic pickling in the presence of sodium hydroxide solution, phosphoric acid (also with addition of butyl alcohol), nitric acid / diethanol (or glycerol) or amidosulfonic acid (Benninghoff, Ei Galvanotechnik 61 (1970), p. 1009-1018 and Berlinghoff, II .: I 'lnish Digest J (1974) p. 291-303).

All of these methods have disadvantages. Nitric acid and nitrites, which require additional wastewater treatment, form during nitric acid / sulfuric acid pickling.

Although stained with chromic acid surfaces are clean and bright metallic, the separation of chromate from the wastewater is known to be very expensive.

Similar problems occur when using peroxodisulfate sulfuric acid mixtures. The chemical treatment of wastewater is particularly associated with the use of iüanioniumperoxodisulfat due to formation of stable Kupfertetraminkomplexe associated with difficulties.

Chemical and electrochemical processes for the complete and partial regeneration of peroxodisulfate pickling solutions have hitherto been proposed exclusively for etching baths for the production of printed circuits. In this case, if bare surfaces are treated as bare surfaces, etching solutions, in contrast to the pickling process discussed here, are used

used, which contain no or only small amounts of sulfuric acid. Bs is always based on a Peroxodisulfatlösung, which in the case of Ainmoniumperoxodisul- ileg in the etching process according to the equation

depleted in ammonium peroxodisulfate and enriched with copper sulfate and ammonium sulfate.

Sine incomplete regeneration of such exhausted etching solutions is by crystallization and separation of GuSO ₄ . (M ₄ ) OSO ₄ . 6 H ^ O and subsequent enrichment of the mother liquor with solid ammonium peroxodisulfate possible (GB-P 1 104 497).

For complete electrochemical regeneration it has been proposed (GB-P 1 141 407) that the double salt GuSO ₄ brought to crystallization by cooling and separated. (HH ₄ ) oS0 ₄ · 6HoO, dissolved in water, to the cathode compartment of a split recovery cell, "while the remaining courage lauge, enriched with IiH ₄ HSO ₄ , fed to the formation of peroxodisulfate in the anode compartment · The exiting anolyte is the regenerated pickling solution After the copper has been deposited, the catholyte is evaporated and the recovered HH ₄ HSO _{4 is} fed back to the anolyte during the next cycle - 40% indicated to eliminate these disadvantages, the anodic regeneration of spent Itzlösung has already been proposed to carry out in divided electrolysis cells with cation exchange membranes as separation systems while working au with a recirculating, stationary catholyte of ammonium bisulfate solution. (GB-P 1 191 O34.) The thereby di The exhausted etching solution supplied directly to the anode chamber is enriched with peroxodisulfate while consuming ADMium sulfate and sulfuric acid, while the Gu ⁺ ions are enriched by the cation exchange.

schermeiabran in the cathode space migrating and deposited at the cathode. However, this very simple process apparatus has the distinct disadvantage that in addition to the Gu-ions and H ⁺ and IiEL ₁ ⁺ -IOn en through the membrane in the Kathoderauin. migrate, whereby only an insufficient reduction of the copper sulfate content in the anolyte is achieved. The depletion of the catholyte on H ⁺ ions due to hydrogen deposition at the cathode and enrichment with Aromoniumiorien also decreases the acid content, while the Ammoniumsulfatgehalfc increases · Bs is therefore necessary to constantly feed the process sulfuric acid and the spent Katholyte ammonium sulfate to withdraw, which additional Expenses required. It has also been proposed (U.S. Patent No. 3,843,504) to perform regeneration in a single constructed, undivided cell using an etching solution containing potassium peroxodisulfate in addition to sodium.

By special flow and temperature control in the cell should be achieved that the sparingly soluble potassium peroxodisulfate precipitates and sediments towards the anode. As a result, the peroxodisulfate content in the cathode region is kept low and, as a result, the reduction loss is reduced. In view of the very complicated rope construction, u. a. With a rotatable cathode and the required rather large anode - cathode distance, this process has no advantages over the other proposed methods, both in terms of the equipment required and the consumption of slektro energy.

Overall, it must be estimated that the well-known for sulfuric acid etching solutions regeneration process adhering to the following basic disadvantages

high consumption of caustic energy of approx. 3 ~ 4 kWh / kg formed peroxodisulfafc, due to the low current yields and the high cell voltages,

_ c -

- High effort by the required special cell designs and / or by the necessary combination of multiple circuits, some with separation and. Recycling of solids.

However, the situation is different when strongly sulfuric acid solutions, as they are essential during pickling, to be regenerated, because 'on the one hand due to the high migration rate of hydrogen ions does not achieve sufficient accumulation of copper ions and on the other hand copper is not eliminated in a compact form. In the case of divided electrolysis cells, the removal of the deposited copper aggravates the problem ·

Object of the invention

The aim of the invention is an environmentally friendly circulation process for pickling copper and copper compounds by means of peroxodisulfate-sulfuric acid solutions to produce oxide-free, bright metallic surfaces at high Stromausb eut e.

Explanation of the essence of the invention

The invention has for its object to find a for the pickling and regeneration process equally favorable composition of pickling solutions, wherein the exhausted solutions are regenerated immediately at the site and the abraded during pickling copper is recovered, as well as high power yields can be achieved by the process control.

Brfindungsgemäß which is achieved in that for the pickling 0.15 to 1.0 INOL / 1 sodium and / or Ammoniumperox'odisulfat and 2 to 4 mol / 1 sulfuric acid solutions containing at '.Temperaturen of 20 to 50 ⁰ C to the the exhausted pickling solutions containing 0.1 to 0.5 mol / 1 copper sulfate and a roast content of 0.1 to 0.65 mol / 1 persulfate, first

a cathodic treatment for the separation of at least 60 % of the copper and for the reduction of the persulphates, in order subsequently to enrich them with peroxodisulphate up to the starting concentration by anodic treatment in a manner known per se.

Surprisingly, it has been found that the current yields of the anodic formation of peroxodisulfate in the exhausted pickling solution after prior destruction of the remaining Persulfat ~ quantities, that is still present peroxodisulfates and peroxymonosulfate formed due to acid hydrolysis, by cathodic treatment is substantially greater than in direct anodic treatment, ie the persulfates are responsible for the very low current yields. On the other hand, all previously proposed electrochemical recovery processes boiled down to carrying out the regeneration of the etching solution while retaining the residual content of persulfate from the previous etching. For this reason, the exhausted etching solution was directly or after previous crystallization of CuSO ^. (IH ^) ₂ S0 ^ fed to the anode compartment of the retrieval cell. In order to prevent a cathodic reduction, even additional process steps or "complex apparatus constructions were accepted. To carry out the pickling, the regenerated solution is brought into contact with the workpieces to be treated in a suitable pickling tank. The exposure time and the pickling temperature within the specified range are determined in a known manner by the material itself, the type and degree of contamination, the type and geometry of the components, the desired etching effect and the surface quality »Bs can be both peroxodisulfates of the hatrium and Ammonium, as well as mixtures of both are used. In particular, mixtures having a molar ratio of from 1: 0.5 to 1: 2 are advantageously usable. Compared with the pure peroxodisulfates, these mixtures can be used to obtain higher solubilities for the reaction products CuSO.sub.2, (MI.sub.2), N.sub.2SO.sub.4, and N.sub.2 H.sub.2 SO.sub.1. This makes it possible to achieve higher degrees of utilization of the formed peroxodisulphate without it leading to a

annoying crystal formation occurs during the pickling process, which has a very favorable effect on the economy of the overall process. The lower limit of the peroxodisulfate content of 0.15 mol / l in the regenerated pickling solution to be observed in accordance with the invention is determined primarily by the fact that a sufficient pickling rate is achieved. Further lowering of the persulfate content of the regenerated pickling solution leads both to the quality of the pickled surfaces. On the other hand, exceeding the upper limit of .1 mol / l of peroxodisulfate with overall good space-time yields due to the solubility behavior of the sulfates formed also leads to unacceptably low degrees of utilization, in particular the low space-time yield Favorable bating results are obtained when equimolar sodium and ammonium persulfate solutions are combined with a starting content of about 0.6 mol / l. In order to achieve approximately the same removal rates in spite of the decreasing pickling rate as the persulfate consumption increases To enable workpieces to be machined, either the Kxpositionszeiten be extended or the pickling speed is maintained by simultaneous increase in temperature at the required level. The latter procedure allows for higher space-time yields and the subsequent copper recovery process can proceed immediately in the favorable temperature range.

For the electrochemical regeneration process, it has also proven advantageous if the pickling solutions contain additional amounts of sodium and / or ammonium sulfate. At the end of the anodic enrichment with peroxodisulfate, sufficient sulphate concentrations should still be present to obtain high stoichiometric yields. Suitably should peroxodisulfate in a conversion degree of 80% _t based on the total SuIfatgemisch present, are not exceeded. ,

The cathodic and subsequent anodic processes to be carried out according to the invention for the regeneration of the spent pickling solution

Treatment can be carried out both in the cathode and anode rooms of a divided electrolytic cell, and in two consecutive electrolytic cells. "

The coupling of an undivided copper recovery cell with a divided cell for peroxodisulfate electrolysis according to a further feature of the present invention has proved to be particularly advantageous for this. It is expedient in the recovery cell for the conditions as smooth as possible, fine-grained cathodic deposition of the copper electrolysis Maintaining copper "In particular, it is necessary to work at current densities of 50 to 200 A / m and temperatures of 50 ^° C, thereby removing the majority of the copper for deposition. Auch © smooth copper deposition favoring additives known inhibitors, such as. B * gelatin, glue, thiourea, urea, etc. can be added to the pickling solution to be regenerated. Subsequently, the pickling solution freed from the bulk of the copper and a large part of the persulfates is first fed to the cathode spaces of the persulfate line, in which the deposition of further small amounts of copper takes place and the reduction of persulfates is continued. In contrast to the copper recovery cell, cathodic work is carried out here in the diffusion limiting current region with simultaneous evolution of hydrogen, wherein current densities of 500 to 2000 A / m ^{2 are to be} maintained according to the invention.

According to the invention, this copper is removed from the cathode by periodic backwashing with depleted pickling solutions still containing residual persulfate. In this way, the cell is regenerated without having to open it and mechanically free from the copper. The depleted pickling solution used for rewinding is returned to the copper recovery cell at the next cycle. This makes it possible in a simple way to recover this copper erant in a pure form suitable for direct further processing.

The after passing through the copper recovery cell and the cathode compartments of the cell for peroxodisulfate electrolysis

freed of at least 60% of the copper electrolyte is then fed to the anodic treatment of Anodenräuiaen these cells, it is carried out electrolysis at current densities of 4000-7000 A / m ² and temperatures of 15 - 35 ° C. For this it is necessary to cool the cells. Your electrolyte can be added prior to entry into the Anodenrauni known, in the peroxodisulfate electrolysis usual polarizers, Konk, entrationsbereich of 0.05 to 0.5 g / l are added, whereby the current yields are favorably influenced. Advantageously, thiocyanate, chloride, urea, thiourea, cyanaiaide, etc. can be used individually or in admixture. It is particularly advantageous to use those polarizers which simultaneously act as inhibitors for copper deposition, eg. As thiourea and urea. In order, on the one hand, to be able to meet the most favorable conditions for copper deposition in the recovery cell and, on the other hand, to minimize electrical energy consumption, it is possible according to the invention to reduce the current capacity of the copper recovery cells to 50 to 90 % of the current capacity of the persulfate electrolysis cell , This is advantageous because Vv ¹ OiI the current efficiency of copper deposition is greater than that of Persulfacbildung and a part of the copper deposit is laid in the Persulfatzelle. This makes it possible to optimally adapt both the anode and the cathode processes to the achievable different current yields.

It is particularly advantageous for the process according to the invention to use peroxodisulfate electrolysis cells according to DD-P 99 546, with which current efficiencies of 70 - bO '/ O at 4.2 V cell voltage can be achieved.

When coupled with a technically customary copper extraction with insoluble lead anodes with about 70 % of the current capacity of the persulfates (cell voltage approx. 2.2 V), a specific electric energy consumption (electrolysis direct current) of 410 kWh relative to 1 1 results regenerating pickling solution with 1 mol / 1 peroxodisulfate. In contrast, in the known methods for the regeneration of etching solutions at

a specified average current efficiency of about 30% and a cell voltage of 6.5 V and a residual content of 0.3 mo1 / 1 persulfate from the previous etching solution 813 kWh / l required · It is clear that in the procedure according to the present invention only Approximately half of the electrical energy is required as in conventional methods, although according to the invention, the remaining persulfate must first be destroyed.

The overall sequence of the pickling and regeneration process in the embodiment of two separate cells is to be summarized with reference to the flowchart FIG. The workpieces are brought into contact with the regenerated electrolyte at the selected exposure times and temperatures in the pickling tank 1. The exhausted pickling solution is discharged into the intermediate vessel 2 and the pickling tank 1 is refilled from the intermediate vessel 3. From the tundish 2, the spent pickling solution is first fed into the copper recovery cell 5 by means of a metering pump for electrochemical regeneration. From there, the partially entkupferte solution enters the cathode compartment K of the cell for the Per oxodisulfatelektrolyse 6, to transfer from there into the anode compartment. When entering the anode compartment potential-increasing additives are added from the storage vessel 7. After anodic regeneration, the regenerated pickling solution returns to the intermediate vessel 3. After several cycles, the exhausted pickling solution from the tundish 2 is supplied via the bypass line directly to the cathode chambers of the peroxodisulfate electrolysis cell by means of the metering pump 4 in order to dissolve the copper deposited there in the currentless state. The solution then passes into the tundish 3, is fed from there via the connecting line 9 directly to the tundish 2 and the next regeneration cycle is ready to start. «Lost solution losses are periodically by supplying Na ₂ SO ₄ , W ^) ₂ SO ₄ , H ₂ SO ^ and water over 10 balanced. ,

The pickling and regeneration process according to the features of the present invention is by no means limited to workpieces

limited to pure copper. In an anologic manner, it is also possible to treat those made of copper alloys, eg , brass. It should be noted, however, that less noble metals, for example zinc, do not undergo cathodic deposition under the conditions of copper electrolysis. There is an accumulation in the electrolyte. which does not adversely affect the quality of the treated workpieces. It is therefore quite possible to use the same pickling solution over several cycles. Thereafter, the entire amount or a to be scrapped after passing through the Kupferrückgewinnungszelle Int eil the exhausted, enriched with zinc sulfate pickling solution by known methods must be freed from the zinc · For this purpose, for example, the remaining copper removed by cementation with zinc and der.Elektrolyt a zinc electrolysis are supplied Solution freed from the bulk of the zinc can be recycled to the process via the anode compartments of the peroxodisulfate electrolysis cell. The copper powder precipitated by cementation can also be fed to the regeneration process after dissolution in the exhausted pickling solution and recovered in the form of electrolyte copper. , '. ^:;: ': "\ [\ [' / ^:: ;;: 'ϊ ·: λ 1 j.:'m...

embodiments example 1

A partially exhausted pickling solution, as obtained from a peroxodisulfate content of 0.6 mol / l during the pickling process after 50% utilization, was prepared in the following composition:

Sulfuric acid 3.0 mol / 1 sodium peroxodisulfate 0.15 mol / 1 ammonium peroxodisulfate O, 15 mol / 1 sodium sulfate 0.35 mol / 1 ammonium sulphate 0.35 mol / 1 copper sulphate 0.30 mol / 1

O, 06 0 12 0 19 0 25 0 , 34 ο, 47 ο, 14 0 25 0 40 0 , 53 0 , 63 0 83 ο, 31 0 , 49 0 til 0 , 87 0 91 at the

The respectively newly used solution was heated at 30, 40 and 50 ⁰ G for several hours and hourly the contents of peroxodi- and Peroxomonosulfat determined by titration by known methods. The proportions of peroxomonosulfate in Gesanitpersulfatgehalt (degree of conversion) are summarized in Table 1 as a function of time.

Table 1

Temperature conversion rates as a function of time

⁰ G 0.5 1 2 3 4 6

30 40 50

It is clear that at 5O ⁰ C after one hour, about half of the persulfate as before peroxymonosulfate ~ is. At 40 ⁰ C, this is the case after about 3 hours at 3O ⁰ C after about 7 hours. It can be seen that even at low pickling temperatures after the 24-hour service life of the bath, most of the peroxodisulfate has converted to peroxymonosulfate.

Example 2

In a divided cell for peroxodisulfate electrolysis with platinum anodes and copper cathodes were each 250 ml exhausted

Pickling solutions treated anodically (2 hours, 4 _f 8 A, 6000 A / m, 25 ° C). 0.2 g / l of ammonium thiocyanate and 0.1 g / l of hydrochloric acid were added as polarizers at the beginning of the electrolysis. The catholyte used was 3 molar sulfuric acid. The anolyte solutions had the following compositions?

sulfuric acid ^ ⁺ ) mol / 1 3 I I , 0 3.0 3 , 0 Sulfates (Na ⁺ ; NH, NH ₄ ⁺ ) mol / 1 1 O , 0 0.8 , 0 Persulfates (Na ⁺ J mol / 1 mm 0.2 • p. _:; copper sulphate mol / 1 2 0.2 0 2 Sinksulfat mol / 1 ">' ^: q 3

Solution A corresponds to a by cathodic treatment naoh the features of the invention of residual Per sulfate ene liberated pickling solution, but still has a residual content of 0.2 mol / 1 copper. In comparison, solution B still contains 0.2 mol / 1 of unspent persulfate, of which 0.15 mol / 1 is present as peroxoinonosulfate. Solution G corresponds to solution A, but contains in addition 0.3 mol / l of zinc sulphate, as is the case with pickling of brass «

The following results were obtained:

Persulfate content after mol / 1 0.61 0.41 0.55 electrolysis Increase in persulfate mol / 1 0.61 0.21 0.55 current yield % 85.1 29.3 76.8

It follows that compared to the comparative solution B in the erfindungsgeraßen procedure greater Persulfatgehalte and significantly higher "current yields are obtained.

In solution B, the present peroxomonosulfuric acid is highly exploitable. It is also clear that not fully deposited copper (0.2 mol / 1 = about 40 % of Ausgangsaienge) has no negative impact on the current efficiency. Aucli at ζ us atz Ii eh. He presence of zinc sulfate are obtained still sufficiently high Strotnausbeuten.

Example 3

Bs were prepared pickling solutions of varying degrees of exhaustion, such as those produced using a 0.1 iaol / 1 peroxodisulfate, 0.25 mol / 1 excess sulfate and 3 mol / 1 sulfuric acid-containing starting solution. Both peroxodisulfates bfew. Sulfates of sodium or ammonium, and equimolar mixtures of the two used liach · 48 hours of standing at room temperature (23 ° C ± 1 ⁰ C) was checked whether sediment had formed. The results obtained are shown in Table 2.

Table 2

crystallization

Utilization degree

Electrolyte composition in mol / l

(BH ₄ ) ₂ S ₂ 0 ₈

Na ₂ S ₂ O ₈

Guso,

H ₂ SO ₄

satanic phenomena

0.40 0.60 - 0.65 - 0.40 3.0 medium 0.40 0.30 0.30 0,325 0,325 0.40 3.0 little 0.40 - 0.60 - 0.65 0.40. 3.0 little

0.35 0.35 0.35

0.65 - 0.6 - 0.35 3.0 little 0,325 0,325 0.3 0.3 0.35 3.0 none 0.65 - 0.6 0.35 3.0 very little 0.70 - 0.55 - 0.30 3.0 very little 0.35 0.35 0,275 0,275 0.30 3.0 none - 0.70 - 0.55 0.30 3.0 very little

0.30 0.30 0.30

It is clear that with equimolar mixtures mixtures higher utilization rates of peroxodisulfates can be achieved without the supersaturation occurs.

Example 4

Bs were pickling solutions of varying degrees of efficiency, such as using different peroxodisulfate Ausgarigskonzentrat ions with; each 25% excess of sulfates and a content of 3 mol / 1 sulfuric acid produced. ,

In all cases, an equimolar mixture of ammonium and Hatriumperoxodisulfaten or sulfate was used. The efficiencies of the persulfate were determined, when exceeded after 48 h at 25 ° C just a beginning crystallization was determined · The limit concentrations determined or the degrees of utilization at room temperatures are summarized in Table 3.

Table 3 Limit concentration for Kri Cu ²⁺ mol / 1 Exploitation usable Ausgangskonz · stallisation 0.35 Degree 0.35 at peroxodis 0.36 0.40 sulfate mol / 1 S ₂ O ₈ ² "mol / 1 0.38 maximum 0,475 0.65 0.40 0.35 0.57 1.0 0.54 0.44 0.40 0.73 · 0.9 0.42 0.5 0,475 0.70 0.8 0.30 0.5 0.57 0.63 0.7 0.16 0.5 · 0.73 0.50 0.6 0  1.0 0.5 0 1.0 0.4 0 1.0 0.3

It can be seen that the maximum degree of utilization given by the solubility increases greatly with decreasing starting persulfate concentration. At an initial concentration =: 0.5 mol / 1, no more crystal formation occurs, but then the usable utilization rate is limited by the achievable etching rate. The usable degree of utilization relating to a minimum limit concentration of 0.15 mol / l of pexoxodisulfate reaches a maximum at the peroxodisulfate concentrations of 0.6 mol / 1 which are preferred according to the invention.

Example ft

After each degreasing, the hot and cold rinsing, a tube sample made of Eupfer with the dimensions 12 χ 1 χ 125 (surface 8.63 × 10 ^J m) was incubated for 10 min at 25 G both with 250 ml freshly regenerated, and with 250 ml of differently used pickling solutions were put in contact with the customer. All electrolyte concentrations refer to a starting solution containing 0.6 mol / 1 peroxodisulfate, 0.15 mol / 1 of excess sulfate (both in the equimolar mixture of MH and Oe salts) and 3 mol / 1 sulfuric acid. After pickling, the increase in the copper content of the solution and from it the erosion rate in mol / 1 Gu as a measure of the Beizgesohwindig. determined. Bs were given the values summarized in Table 4.

Table 4

Composition of the pickling solution 0.15 CuSO ₄ H ₂ SO ₄ Exploitation Cu excavation mol / 1 0.25 0.0 3.0 degree of Per - mol / 1 rate of Cu 0.35 0.1 3.0 sulfates mol / m ² Persulfate sulfate 0.45 0.2 3.0 0,000 0.0167 0.484 0.6 0.55 0.3 3.0 0.167 0.0129 0.374 0.5 0.65 0.4 3.0 0.333 0.0116 0,336 0.4 0.45 3.0 0,500 0.0099 0.287 0.3 0,667 0.0065 0,189 0.2 0,750 0.0038 0,110 0.15

When using the pickling solution with 0.15 mol / 1 persulfate, as expected, incipient crystal formation was observed. All other solutions remained clear ·

Example 6

For determination of the temperature door depending on the pickling rate peroxodisulfate 1 to 50% unused pickling solution at various (temperatures _ge "has been under the same conditions of example 5 with an even 0.3 mol / containing pickled. The results are summarized in Table 5.

Table 5 Cu excavation middle mol / 1 rate of Cu pickling temperature mol / m ⁰ C 0.0078 0.226 21.0 0.0097 0.281 27.8 0.0121 0.351 32.5 0.0153 0.444 38.8 .0191 0.554 45.0

The evaluation showed that by increasing the temperature from 20 to 5O ⁰ C is increased to about 3 times the pickling rate is reached. Since, on the other hand, according to the results of Example 5, the pickling rate decreases to about one third with an increase in the utilization rate to 80 % , this drop in speed can be approximately compensated for by a corresponding increase in tempera ture.

Example 7

The pickling and the electrochemical regeneration of the pickling solution were in a technical system, analogous to that in EIg. I illustrated flow chart performed. The copper recovery cell used was a technically common construction with copper cathodes and lead anodes in monople circuit. Four individual cells with 7 pairs of electrodes and one electrode flowed through successively by the electrolyte were

2 area of 5.6 m per cell used · As a cell for the peroxodisulfate electrolysis used a Bieber presser electrolyzer type BZ II according to DD-P 99548 with 6 bipolar cells with Pt-Ta strip electrodes and cathodes of impregnated graphite. , , '. First, the cathode chambers, then the anode chambers, were successively passed through by the electrolyte. The power capacity

the copper recovery cell was 4,400 A at 2,400 A, that of the 6,600 A persulfur line at 3600 A. The cathodic current density at the recovery line was 107 A / m and that of the peroxodisulfate line was 1,200 A / m ² . The anodic

Current density at the platinum electrodes was 5,400 A / m ·

Bs was a pickling solution with a starting concentration of 0.6 inol / 1 and a Eestgehalt of copper of 0.03 mol / 1 used and up to a residual content of 0.2 mol / 1 Persul fat and 0.43 mol / 1 CuSO ₄ used for pickling at 45 ° C "The spent pickling solution was pumped through the cells at a rate of 89 l / h. Thus, the starting concentration of about 0.6 mol / 1 peroxodisulfate and about 0.43 mol / 1 CuSO ^ was just reached when exiting the Peroxodisulfatzelle anolyte. This results in an average current yield of peroxodisulfate formation of 79.5%. At the same time, 76 % of the copper in the form of electrolytic copper was deposited in the recovery cell and 17 % in the persulfate cell, ie a total of 93 % of the copper present.

Since the cell voltage of the copper recovery cell was 2.1V, that of the persulfate line was 4.2V, the electric power consumption per hour was 20.14 kWh. Based on the anodically newly formed peroxodisulfate of 0.4 mol / 1, this results in a specific electrical energy consumption of 2j4ö kWh / kg.

The regeneration of the cathodes of the persulfate cell was carried out after several cycles by backwashing with an exhausted electrolyte solution.

Claims (11)

43 claim. 1. Circulation method zubi pickling of copper and copper alloys with peroxodisulfate and sulfuric acid-containing aqueous solutions and simultaneous recovery of the copper, characterized in that 0.15 to 1.0 mol / 1 sodium and / or ammonium peroxodisulfate and 2 to 4 öiol / l sulfuric acid containing solutions at temperatures of 20 to 50 C are brought into contact with the workpieces to be treated and the exhausted pickling solutions containing 0.1 to 0.5 mol / 1 copper sulfate and a residual content of 0.1 to 0.65 mol / 1 persulfates first subjected to a cathodic treatment to the deposition of at least 60 % of the copper as well as for the reduction of the persulfates to then enrich them by anodic treatment in a conventional manner with peroxoaeisulfate to the initial concentration. 2 current densities of 500 to 2,000 A / m is deposited. 2. The method according to item 1, characterized in that the regenerated pickling solutions sodium and ammonium peroxodisulfate in a molar ratio of 1: 0.5 to 1: 2. 3 · Method according to points 1 and 2, characterized in that preferably pickling solutions are used with a starting content of peroxodisulfate of about 0.6 mol / 1. 4. Process according to items 1 to 3 » characterized in that the pickling solutions additionally contain sodium and / or Aiiffiioniumsulfat. Method according to points 1 to 4, characterized in that the pickling process is started at room temperature and the pickling time is prolonged and / or the temperature of the pickling solution is increased with increasing degree of fatigue. 6. Process according to items 1 to 5 », characterized in that the cathodic treatment in undivided copper recovery lines and / or in the cathode compartments divided cells for Peroxodisulfatelektrolyse takes place. Process according to items 1 to 6, characterized in that the majority of the copper to be cathodically regenerated is present in a copper recovery cell in the case of cathodic see current densities of 50 to 200 A / m, the rest in the cell for peroxodisulfate electrolysis in cathodic 8. The method according to the points 1 to 7 » characterized by by the fact that at the cathodes of the cells for Peroxodisulf at electrolysis deposited copper is periodically detached by rinsing with exhausted pickling solutions and the copper recovery cell is supplied. 9 · A method according to items 1 to 8, characterized by that the anodic treatment in the anode compartments of divided cells to Peroxodisulf at electrolysis at Strojji- densities of 4,000 to 7,000 A / m and temperatures of 15 to 35 ⁰ C. 10. The method according to points 1 to 9 » characterized in that the pickling solution to be regenerated before the anodic treatment 0, o5 to 0.5 g / l of suitable polarizers, eg. As thiocyanate, chloride, urea, thiourea, cyanamide, inter alia, be added individually or in a mixture. 11. Method according to items 1 to 10, characterized by that the current capacity of the Kupferrfcckgewinnungszelle is reduced to 50 to 90 % of the current capacity of the cell for peroxodisulfate electrolysis. For this 1 sheet drawing