JPS60245796A - Treatment of purge solution for particularly designing for electrolytic zinc extraction - 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 Technical Background The present invention utilizes an electro-extraction process for recoverable metals, such as zinc, involving a membrane electrolysis process. The present invention relates to a method for treating an e-di solution.

The inventive method of electrolytic treatment aimed at producing a purge solution reduced in zinc and sulfuric acid is hereinafter referred to as electro-electrodialysis.
Extraction according to a).

The present invention also relates to a method for installing an ion exchange membrane.

Hydrometallurgy and Electrolysis) The production of zinc by K involves a final operation in which it is treated by electrolysis of a solution obtained by leaching of sulfuric acid from a torrefied sulfide ore.

Some of the impurities of the ore enter the solution during the leaching stage and can more or less completely escape the purification stage carried out before electrolysis. Eventually, impurities that are not deposited on the electrodes will be concentrated in the electrolyte. As the concentration of impurities becomes too high, the solubility of zinc sulfate decreases and the impurities tend to inhibit the steps of the electrolysis process. Therefore, a fraction of the electrolytic solution is purified (
purge). The disadvantage of this cleaning operation is that it results in significant losses of zinc and sulfuric acid, and in addition leads to contamination of the metal.

The invention relates to a special treatment of the purge solutions withdrawn from the individual stages of the extraction process.

To understand the essential features of the present invention, it is first necessary to be familiar with the conventional methods used in the art. FIG. 1 is a diadem diagram schematically illustrating one example of a conventional electrolytic zinc extraction method. Number 10 indicates torrefied sulfide ore, which constitutes an essential raw material. The sulfide ore dissolves zinc, so leaching is maximized12
and prevent the dissolution of impurities as much as possible. in general,
Leaching includes three operations: a neutralizing leaching operation 12a, an acid leaching operation 12b, and an iron precipitation operation 12c. as a matter of fact,
After treatment of acid leaching and iron precipitation, the resulting solution is subjected to neutralization leaching. The raw leaching solution obtained by this neutralized leaching (number 1
4) to the purification operation (No. 16). These operations are
Impurities that can inhibit electrolysis, especially @, cadmium, and nickel.

This is done to actually completely precipitate cobalt, etc. The resulting solution 18 is a purified solution rich in zinc sulfate. This solution is then subjected to electrolysis 20.

For example, this solution undergoes several electrolysis in a cascade, as shown at numbers 2°a and 20b. Zinc is deposited on the cathode and the reduced solution 22 after electrolysis contains a large amount of sulfuric acid, so it can be recycled for leaching of ore IO. In this way, these series of steps are carried out in a closed loop, such as the purification stage 16, the electrolysis stage 20 or the residue precipitation stage (12b).

It should be noted that non-disappearing impurities can accumulate in 12c) and reach even higher values.

These leaching residues contain iron, which is present in the ore in various forms, depending on the extraction method used. Iron can be insolubilized in the form of goethite, hematite or jarosite. In the case of jarosite, along with iron, alkali elements (Na + * K'' and h ), sulfate ions (SO
42-) and water are observed. This removal method uses electricity
There are many advantages when using electrodialytic extraction.

The rate of cleaning that maintains the residual impurity concentration below an acceptable critical concentration is thus determined. The main impurity, the impurity that determines the cleanliness rate of the plant, is generally magnesium. This is because most zinc ores contain magnesium. When using electrolytic extraction of zinc, the concentration of magnesium is 15-20
Exceeding g/no causes certain problems. The problems caused by magnesium are magnified when the concentrate used as raw material is a dolomite type ore.

Another impurity that can cause some problems if it accumulates is manganese. Although the presence of this element is necessary,
Do not exceed certain concentrations.

Halogens, particularly fluorine and chlorine, also accumulate in the electrolyte.

This can lead to interference with the electrolysis of zinc sulfate. However, since it is the magnesium that most often determines the nodal rate in a zinc electrowinning plant, the present invention will be described below with respect to the separation of magnesium. However, those skilled in the art will readily understand that the present invention is also applicable to other impurities that may accumulate.

The solution can be recovered from one or more different stages during operation of the process. For example, /9-di24
corresponds to the recovered crude leach solution rich in zinc sulfate. As shown in the figure, 1.e-di refers to a portion of the purified solution enriched in zinc sulfate. 1.e-di can also be carried out between several process steps during electrolysis (see figure 28).

However, in most cases, a solution lacking zinc sulfate that has undergone electrolysis is subjected to the injection (30 in the figure). Purging of this (zinc sulfate) deficient solution appears to be the most prudent. This is because this solution contains a minimum amount of zinc, which is a useful product. However, this solution is highly acidic and requires the use of a large amount of neutralizing agent.

The processes commonly used in the processing technology of the present invention are, on the one hand, neutralization-precipitation processes and, on the other hand, concentrate preleaching processes. Sometimes the solution may be subjected to electrowinning before neutralization-precipitation.

Although it is rare, /? -disolution 30 can be commercially available directly.

For example, a neutralized purified solution of zinc sulfate can sometimes be used directly in the production of zinc salts or lithopone. Similarly, products obtained by direct distillation of solutions can sometimes be commercially available. However, given that the market for such products is small, these are relatively isolated cases.

However, all of these solutions are modified in conjunction with the specific environment of the zinc electrolysis plant or the external market, which in some cases can have an impact on the operation of the main process. One of the objects of the invention was incorporated into the main process. An object of the present invention is to provide an e-mail processing method.

Different treatments have also been tried to treat these /R-di solutions. For example, zinc may be directly extracted by immobilization on an ion exchange resin or liquid-liquid extraction, or conversely, there is a method in which sulfuric acid is immobilized on an ion exchange resin. but,
These latter processes have not actually achieved any industrial results.

Attempts have also been made to treat the deletion solution with dialysis and electrodialysis. The dialysis process produces a moderately dilute acid that can be recycled and a low acidity solution containing all metal cations. Next, zinc can be extracted by neutralization, solvent extraction, etc. The electrodialysis process produces recyclable sulfuric acid and allows disposal of neutralizable low acidity magnesium-containing nodules. However, even with these processes, commercial success was not achieved. □ SUMMARY OF THE INVENTION The present invention relates to a method for the extraction of recoverable metals, such as zinc, by electrolysis, wherein the electrolysis comprises, in the case of electrolytic recovery of zinc, one of the streams of a purified solution enriched in zinc sulfate. Applies to the Department. The pH of this purified solution is advantageously between 2 and 5 and the zinc content between 100 and 150 I/no. A portion of said flow forms the purge.

In the following description of the invention, only the case of purging in a copper-zinc plant will be discussed.

The solution processing of the present invention includes two basic steps.

Extraction step by electro-electrodialysis of zinc monosulfate solution.

This step is an electrolysis carried out in an electrolysis device having several chambers separated by anionic membranes, ie anion exchangers. This extraction can be carried out in a series of electrolyzers or in several successive devices arranged in cascade.

Common reagents such as monolime, sodium hydroxide or sodium carbonate are used. Neutralization step of the purge solution lacking zinc sulfate.

During this step, manganese is subjected to a specific oxidation treatment in the form of manganese dioxide, which can be selectively removed from the nozzle.

Precipitation by neutralization is preferably carried out in stages in order to recover the valuable metals contained in the purge.

Although not limiting, it may be useful to clarify the rationale underlying the invention. This includes electrolysis carried out in an ellipse where the catholyte and anolyte are separated by an anion exchange membrane.

The metal to be recovered is deposited on the cathode. however,
For example, the existence of reactions, which can be referred to as parasitic reactions, which can reduce protons and form a system of emitted water cannot be excluded. Under the action of the applied electric field, anions, especially sulfate ions, move from the catholyte through the exchange membrane towards the anolyte, whereas ions, in principle, cannot pass through the exchange membrane.

The reaction that predominately occurs at the 7 node is water oxidation, which is K
Therefore, oxygen is generated and protons are generated.

In this way, the constituent elements of sulfuric acid can be recovered. Furthermore, certain impurities, such as manganese ions, also lose K during the oxidation process.
H+ ions can be produced. This is shown by the following electrochemical overall reaction equation.

Hh O→OH+ 2 H++ 2 eMn″” +
2 HzO-MnOm + 4 H" + 2 eHowever, there is no perfect anion exchange membrane. That is,
Anion exchange membranes are particularly characterized by a lack of selectivity towards protons.

The selectivity of an anion exchange membrane for sulfate ions can be characterized by the apparent transport number of sulfate ions in the membrane, as defined by the equation below.

t804===”B.4-/Ia Here, Eng.

4 is the current density carried by the sulfate ions in the membrane and IT is the total current passing through the membrane.

During the research leading to the present invention, it was found that this transport number depends, inter alia, on the specific membrane, the acidity of the 7-node fluid, and the temperature, according to the experimental model equation below.

t(SO4--)=A-B(H) Anolyte where A and B are constants that depend on the membrane, the current surrounding environment and temperature.

Anionic membranes that tend to exhibit ideal behavior have a coefficient A that tends to approach IK, and a coefficient B that tends to approach O. Experiments have shown that this deviation from ideal behavior is due to the transfer of protons from the anolyte to the catholyte.

One of the features of the invention lies in the fact that by adjusting the acidity of the anolyte, deviations from the ideal behavior of the membrane are at least partially eliminated.

This adjustment may be carried out by any suitable means compatible with the rest of the electrolysis main circuit. However, it has been found to be particularly advantageous to adjust the acidity by determining the appropriate flow rate of the anolyte solution. This flow rate must be such that the acidity at the outlet of the anode chamber is between 09l and IN.

When applying the invention to a zinc electrolysis plant, all nearly neutral (less than 0, IN) solutions may meet the conditions specified above. Mention may be made, for example, of electrolyte solutions or neutral purified solutions, solutions obtained by filtration, and various cleaning solutions before and after use. Mention may also be made of ferrous sulfate solutions, in which case instead of water oxidation a different anodic reaction is utilized, namely the oxidation of ferrous to ferric iron.

With respect to one of the objects of the present invention, namely to provide a 9-di product which excludes zinc as much as possible and has as low an acidity as possible, it is necessary to completely satisfy these two conditions by the above-mentioned measures, namely: It has been observed that limiting the transport of H+ ions from the anolyte to the catholyte is insufficient. In fact, in the course of the research leading to the present invention, a particularly effective supply corresponding to the above conditions was the supply of a neutral (neutralized), i.e. purified, electrolyte solution to the cathode compartment, i.e. a possible supply of anolyte. Experiments have revealed that it is one type.

In order to obtain a high quality cathode, the acidity in the cathode chamber should be approximately 0. It was possible to decide to maintain a value higher than IN.

However, as mentioned above, it is desirable that the acidity of the nozzle at the outlet of the cathode chamber be as low as possible. Therefore, the acidity condition regarding the quality of the cathode chamber outlet and 79
- Includes harmonization between conditions regarding the acidity of di. A good match is to choose the acidity of the catholyte to be t-0,1-IN, preferably around 0.6N.

Although it is technically possible to reduce the zinc concentration to extremely low levels, i.e. below 5 f/l, the technology used and the energy consumption prohibit such a reduction. It seems that Using conventional techniques, it is therefore preferred in any case to limit the zinc concentration in the /e-di to 10 to 40 f/l in the first step of electrolysis.

The amount fed to the cathode compartment is determined by the amount of impurities to be pumped. Once the above conditions regarding catholyte acidity are given, the anolyte supply flow rate can be determined. Experiments have demonstrated that the anolyte to catholyte flow ratio can vary from about 5 to 20. It has been found that on the one hand there is an increasing tendency for the formation of concentrated acid, and on the other hand there is a tendency for the temperature to increase. These various problems can be solved by recycling the anolyte and catholyte in the heat removal system. This heat removal system is advantageously an air cooler or an evaporator.

Recirculation of the electrolyte - anolyte or catholyte - in the cooling tower, commonly used in zinc electrolysis brands, is suitable for regulating the temperature of the solution to values below 40°C.

It is also possible to adjust the temperature of only the catholyte.

In this case, the electro-electrodialytic extraction of the zinc sulfate solution proceeds with a positive temperature gradient between the anolyte and the catholyte. This temperature difference is made possible by the use of membranes and can reach 20-30°C. That is, the maximum temperature of the anolyte can reach 60 to 70°C, and the maximum temperature of the catholyte can reach 40°C.

These new processing conditions also constitute one of the inventive features of the present invention. These conditions achieve a reduction in sliding voltage and improve the selectivity of the anionic membrane. That is, the flow rate of the seven-node electrolytic solution required for a given flow rate of the nozzle solution and a given composition of the catholyte solution can be significantly reduced. Examples 3 and 4 fully demonstrate such processing methods and advantageous temperature effects.

By allowing evaporation during cooling of the anolyte and by the occurrence of the phenomenon of electroosmosis as described below, the 1ξ-di flow rate after extraction by electro-electrodialysis can be significantly reduced compared to the cathode chamber feed flow rate. It is possible to reduce the Therefore, without the need to change the zinc concentration of the effluent solution,
The waste fluid flow rate can be minimized to minimize the total amount of zinc and sulfate to be recycled. This advantageous result also increases the recovery of metallic zinc.

In order to comply with the current regulations of the industry and for economic reasons, it is necessary to incorporate a zinc removal and/or recovery step into the treatment of a zinc sulfate depleted catholyte. Such removal and/or recovery can be accomplished, for example, by selective precipitation with a base. This base is for example selected from the group consisting of alkali metal hydroxides and carbonates. The low acidity of the consumable catholyte allows for savings in base and allows the use of resinous or liquid ion exchange compounds.

After the deposition step, the zinc-containing precipitate can be separated from the mother liquor and reused in the zinc leaching step, more particularly in the leaching process. Furthermore,
It is advantageous to neutralize the upper groove after deposition with a suitable base in order to remove impurities whose disposal is restricted. When manganese and magnesium are present in the effluent, a two-step precipitation can be carried out to separate the magnesium from the manganese. For this purpose, any method known to the person skilled in the art can be used, in particular those which produce a precipitate that is basic and at the same time oxidizing to manganese.

Regarding processing details, a person skilled in the art may, according to local conditions,
The zinc-depleted solution resulting from the cathode compartment can be treated in a variety of ways.

According to a first embodiment, all metals present in the depleted catholyte can be rapidly precipitated using sodium hydroxide or lime. When lime is used, the liquid after treatment is essentially pure water and can optionally be disposed of or recycled. When neutralized with sodium hydroxide, a sodium sulfate solution is obtained. When the zinc zonation includes a jarosite precipitation step, the sodium sulfate solution may be used in that step.

In a second embodiment, the depleted catholyte is oxidized with a strong oxide, such as ozone, persulfate, or chlorine dioxide, and a base, which may be a weak base, to precipitate manganese dioxide. Since manganese dioxide is required in the main circuit, said manganese dioxide is effectively recycled in the main circuit. After removal of the manganese, zinc can be precipitated under adjusted pH using methods known to those skilled in the art to obtain zinc hydroxide and/or basic zinc sulfate. This precipitate may be used and recycled in the main circuit. This precipitate may be used to precipitate manganese dioxide. The manganese and zinc removed solution is then neutralized to precipitate the magnesium. It is also possible to use sodium hydroxide or lime in this step. In the case of sodium hydroxide, manganese can be removed to the final trace amount, and in the case of lime, the removal is not complete, but the cost of precipitation is low. When using lime, complete precipitation is obtained using two-stage precipitation. That is, a base stronger than lime, such as sodium hydroxide, is used in the second step.

The present invention further provides a method for electrowinning zinc.

The method of the present invention comprises: leaching a calcined sulfide ore to form a crude leaching solution enriched in zinc silosulfate; 1 purifying the crude leaching solution to form a purified rich solution; Electrolyze to form a zinc monosulfate-depleted solution with zinc depositing on the cathode, and reuse the zinc monosulfate-depleted solution in the leaching process.

- IQ-digesting a portion of at least one of said various solutions so that the concentration of impurities, such as magnesium, which have not actually been separated by the purification treatment and the electrolytic treatment does not exceed a predetermined limit value. That's the type of method.

According to the invention, the Q-sing is performed by separating a portion of the purified rich solution. The method further comprises treating the purge solution by a treatment step as described above, with the anolyte formed during treatment being sent directly to a zinc recovery step.

According to the present invention, either a homogeneous membrane or a heterogeneous membrane can be used, but it is preferable to use a heterogeneous membrane because it has excellent mechanical strength.

The invention therefore also relates to a method for attaching a heterogeneous membrane having selective permeability and comprising a substrate and a coating.

This method involves moistening the membrane, bringing it into close contact with the seal forming the closed loop, keeping the membrane part inside the closed loop forming seal in a moist state, drying the membrane part outside the closed loop forming seal, and drying the membrane part outside the closed loop forming seal. exposing the substrate of the membrane and adhering the dry portion to a support.

In the case of homogeneous or non-homogeneous membranes, the membrane is fixed to the frame by techniques known to filter press manufacturers, or
Alternatively, it is fixed between a frame with a groove and a closing elastic seal that is pressed into the groove.

That is, the membrane is fixed between the groove and the elastic seal. Preferably, the groove is a di-shaped groove.

The process of the present invention provides many advantages.

Part K: The solution that is actually purged comes from the catholyte of electrodialysis, and the sulfate ions in the catholyte are extremely low because the membrane is anionic.
Very little loss of sulfuric acid.

(Left below) Second, since the acidity of the catholyte is low, residual zinc can be easily recovered.

Zinc is recovered from the cathode in extremely pure form.

Overall, electroosmosis occurs due to ion movement across the anionic membrane from the catholyte to the anolyte. the result,
The amount of curd liquid to be processed is reduced.

It was found that the life of the anode is extremely long.

Additionally, this process is extremely clean and can be easily integrated into existing electrolyte systems.

Finally, due to the low acidity of the electrolyte, the processing conditions are significantly better compared to conventional electrolysis methods.

Further features and advantages of the invention will become clearer from the following detailed description based on non-limiting embodiments illustrated in the accompanying drawings.

Description of preferred specific examples FIG. 2 shows the main processing steps of the processing method of the present invention.

A purified solution 26 rich in zinc sulfate is conveyed to an electrodialysis cell 31 . The tank 31 has a cathode chamber 32 and a seven-node chamber 34 separated by an anion film 36 .

In the cathode chamber, zinc is deposited on the cathode as shown at 38, and the catholyte depleted of zinc is taken out as shown at 40. In the anode chamber, sulfate ions enter the anode chamber from the cathode chamber, so the concentration of sulfate ions increases. Acid-rich solution 42 may be removed from the anode chamber and recycled to the electrolytic step of the zinc extraction process.

The depleted catholyte 4o is then neutralized with lime to a pH of about 5.5 in a neutralization step 44. Zinc precipitates in the form of basic sulfate. In a deposition step 48, heavy substances 5o containing basic salts may be separated from the effluent 52 containing manganese and magnesium.

The effluent 52 is neutralized in a separate neutralization step 54 to about 9 to 12 silica by lime 56. In forming material treatment type 58 , a solid component 60 containing manganese hydroxide, magnesium hydroxide, and calcium sulfate is separated from the effluent 62 . Effluent 62 may be recycled upstream of the torrefied sulfide ore leaching process, or may simply be disposed of after readjusting the pH to 8.

Since the heavy material 50 containing zinc is reused in the leaching step 12 and the anolyte 42 is reused in the electrolysis step, the products removed are only the zinc 38 and solid components 60;
If so, the effluent 62 is also removed.

Before explaining the conditions for carrying out the above-mentioned process, it would be appropriate to consider in detail one example of a tank of a demolding electrolyzer used in this process, with reference to FIG.

More specifically, the electrolytic cell shown in FIG. 3 has a cathode chamber 32 and an anode chamber 34, and the two chambers are separated by an anion membrane 36. The tank has a container 62 containing a cathode 64 and an anode 66. Advantageously, the anode 64 is made of aluminum and the cathode P66 is made of lead or a lead-silver alloy. Purified solution 26 introduced into the circulation loop
Excess catholyte corresponding to the amount of overflow 68
The catholyte then enters the receiving vessel 70 and is then discharged at 72 as spent catholyte.

The catholyte circulates in the tank, a portion 74 of which is removed from the bottom of the tank and introduced by pump 6 into a heat exchanger 78 . Heat exchanger 78 maintains the catholyte at, for example, 40° C. to account for indirect heat loss of the catholyte. The catholyte is further sent to a pH measuring device 80.

Considering the anolyte, the anolyte overflows from overflow 82 and enters deposition device 84 . In a sedimentation device, when precipitated M n O2 is present, this M
n0z can be separated as at 86. The effluent forms a rich solution 42 that is sent to the electrolysis process. The anolyte also has the advantage of being circulated, a portion of which is removed through an outlet 88 formed at the bottom of the vessel and sent by a pump 90 to a heat exchanger 92. The anolyte is heat exchanger 9
2, the temperature was maintained at 40°C to 70°C, then the pH
It is sent to a measuring device 94.

Advantageously, the distance between the cathode and the membrane is 40 meters and the distance between the anode and the membrane is 20M. Preferably, the anolyte is introduced across the electrode, and the catholyte is supplied from above. Furthermore, since the permeability of the membrane is essentially zero, the catholyte can be positioned higher than the anolyte. In this way, the catholyte, which has a lower density than the anolyte, overflows and creates a differential water pressure on the membrane.
l hydrostaticpressure) is maintained.

Purification solutions used for purging typically have high concentrations,
It often contains about 150 g/l of zinc. Magnesium is present at a concentration of approximately 159 y/l and manganese at a concentration of approximately 7.5 y/l. l) H is approximately 5.

If the source of the anolyte to be acidified is a purified neutral solution, the 7node has a temperature of about 150F! /l of zinc, but the catholyte contains only 5-40 g/l of zinc. In fact, this low concentration is due to the zinc deposited on the cathode. The amount of solution introduced is adjusted so that the zinc concentration is maintained at this level during the process. The acid concentration in the electrolyte is 0.1-0.6N.

The current density is preferably about 200-800 A/m2, more preferably 400 A/m''.

However, it is desirable that this acidity is at least 0.6N. This is because, if the pressure is less than 0.3N, the zinc deposits produced will be brittle and take on a dendritic shape. Similarly, in order for the zinc deposits produced to be hard and smooth,
The current density and catholyte temperature are approximately 800 A/m” respectively.
, it is desirable that the temperature does not exceed 50°C.

The faradic efficiency of the reaction is 0.75-0.95, and when the faradic efficiency reaches near the upper end of the above range, i.e. 0.95 or above, the zinc is near the maximum, i.e. 409/l.
K is enriched.

Commercially available anion exchange membranes are suitable for carrying out the method;
Heterogeneous (he) sold at 0NACA3475
Preference is given to using a terogeneua) membrane.

In fact, using this membrane it is possible to advantageously
This film can be strongly attached and fixed to the frame.

According to the assembly method of the invention, the entire membrane is first moistened and then, while still wet, abuts against the seal to form a sealing buckle. The inner part of the seal is then left moist and the part of the membrane outside the seal that is in contact with the sealing loop is allowed to dry. As soon as the outer part is dry, the active coating can be peeled off around the woven support (woven substrate + 5upport), usually consisting of polypropylene or polyvinyl chloride, attached to a plastic frame.
Hail!

The treatment method of the present invention includes neutralizing the depleted catholyte formed by electro-electrodialysis.

The reaction is carried out at a pH of about 5.5 and zinc is precipitated according to the reaction equation below.

Horse804 + CaO-+Ca5o4 + H2O7Z
nSO4+ 6 CaO+ 10 H2O-+ 6 Z
n(OH)2 ZnSO4, 4H3O+ 60aSO4
Due to deposition, basic zinc sulfate and gypsum separate. These are returned to the leaching process. The gypsum is then removed along with the leaching residue.

The liquid effluent from the deposition is further neutralized to precipitate manganese and magnesium according to the reaction:
H9-10.

H,0 MnSO4+ CaO-+ Mn(OH)1 + Ca
5O4H,0 Mg5o a →-CaO4Mg(OH)2 + Ca
These neutralization operations for SO4 can be carried out according to conventional methods and methods known to those skilled in the art, and therefore will not be described in detail.

Sodium-containing basic agent (NalCOs or NaOH)
to precipitate the zinc separately from the manganese and magnesium, resulting in a final liquid effluent consisting of sodium sulfate.

This effluent is recycled to the iron precipitation stage of the process using a process that uses jarosite as the waste iron carrier.

Non-limiting examples are provided below so that those skilled in the art can easily select operating conditions suitable for each case.

Example 1 An electro-electrodialysis extraction process of a zinc sulfate solution was carried out using the laboratory-scale apparatus shown in FIG. The composition of the electrolyte mainly depends on the composition of the purified neutral solution, the flow of neutral solution into the anode chamber of the electrolyzer (Da), and the ratio of Da to the flow of neutral solution introduced into the cathode block (DC). will be determined.

The results are shown in Table 1. These experiments were performed using an experimental tank with an electrode surface area of 1 cm" and an average current density of 400 A.
/m”, the result of an experiment at an electrode temperature of 40°C.Da
Flow and Da flow refer to the effluent flow of the anode chamber or the cathode block, respectively. To further improve the quality of the zinc deposit, add 151nf! to 1tHp of neutral solution fed to the catholyte. Bon e glce is not included.

Table 1 Example 2 The apparatus shown in FIG. 4 was used. The purified neutral solution 26 was supplied to the anode chambers 34 of the various electrolyzers and the cathode chambers of the first row of Japanese cypress.

The depleted catholyte 95 leaving the cells of this row is supplied to the cathode circuit 32 of the second row of the electrolyzer. This structure of the electrolytic cell has the advantage that it is possible to extract as much zinc sulfate as possible from the solution while minimizing the consumption of electrical energy required for the process. The anolyte withdrawn from tanks 98 and 97 is transported for the main step, electrolysis.

Table 2 shows the results of operating a two-cypress cascade consisting of a central cathode chamber and two outer anode chambers. The effective surface area of each cell electrode is 0.275 m'',
Purified neutral solution 26 contains 136 g/l Zn, 71
1/l Mn, 16. It is composed of F/L Mg and 0, IN H2SO4.

Example 3 A large-scale experiment was conducted at a zinc electrolysis plant.

The test device has an active surface area of 0.275 for each type of cathode.
It consists of three vessels of 1.0 m'', a cathode diaphragm case and two Pb/Ag anodes.

The production amount of cathode zinc per tank is 3. I Kp
/ day.

In the oak, purified Zn5 with a pH of about 4 is usually used for one tank of cathode chamber.
Oa solution per hour, jl11.20t.

Purified ZnS with a pH of about 4 for one anode chamber
O4 solution per hour p9. ot.

supplied.

The current intensity was 110 A/hr.

The temperature of the cathode chamber and anode chamber was 38°C.

Under the conditions described above, the following results were obtained.

Analysis Cathode solution Anolyte Hz Soa (N) 0.40 0.40Zn (S
/C) 40 139 The catholyte outflow was 0.98 t/h.

The Faraday efficiency was 98%, and the terminal voltage of the cypress was 6.25V.

The zinc deposit was dense and easily peeled off from the supporting cathode.

The lead content in zinc is 10. It was less than F/.

Even after continuous operation for 9 tons with the same exchange cloth and the same flow supplied to the cathode and anode chambers, no change in free acidity or voltage was observed.

Example 4 Using the same equipment as in Example 3, the operation was repeated by increasing the temperature of the cypress anode chamber.・The tank usually contains purified ZnS with a pH of about 4 for one tank of cathode chamber.
1.20 tons of O4 solution per hour, and 93 tons of purified ZnSO4 solution with a pH of about 4 to one anode chamber per hour. OL.

supplied.

The temperature of the cathode chamber is 42℃, and the temperature of the anode chamber is 62℃.
And so.

Under the conditions described above, the following results were obtained.

Analysis Cathode liquid Anolyte H2804 (N) 0.55 1.12Zn (S/
C) 41 138 The catholyte outflow was 0.94 t/h.

7 Alladay efficiency is 98%, terminal voltage of the tank is 5,
It was 2v.

The zinc deposit was dense and easily peeled off from the supporting cathode.

The lead content in the zinc was less than 1.0 g/.

Example 5 Using the same equipment as in Examples 3 and 4, the experiment was repeated by increasing the temperature of the anode chamber of the tank and supplying water to the anode chamber instead of the purified zinc sulfate solution.

The tank usually contains purified Zn5O with a pH of 4 for one tank cathode chamber.
i solution at J1.20t per hour.

2.4 tons of water per hour for one anode chamber.

supplied.

The temperature of the cathode chamber is 42℃, and the temperature of the anode chamber is 62℃.
And so.

Under the conditions described above, the following results were obtained.

Analysis Cathode solution Anolyte H2804 (N) 1.24 1.15Zn (S/
C) 4'0 - The catholyte effluent flow was 0,917 hours.

The Faraday efficiency is 95 inches, and the terminal voltage of the battery is 3.
It was 8v.

Zinc deposits are dense and easily peel off from the supporting cathode.

The lead content in the zinc was less than 1 oy/y.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of an example of a conventional electrolytic zinc extraction process, FIG. 2 is a schematic diagram showing the use of the treatment method of the present invention, and FIG. 3 is a schematic diagram of an example of the process of zinc extraction by electrolysis. A schematic cross-sectional view of a suitable electrodialysis cell, FIG.
FIG. 4 is a schematic diagram illustrating the use of the two-step method of the present invention to deplete the fuel. 12... Leaching process, 31... Electrodialysis tank, 32...
...Cathode chamber, 33...Anode chamber, %...Anion film, Required...Neutralization process, 48...Deposition process,
64...Cathode, 66...Anode, 68.8
2... Overflow, 70... Receiving container, 76.
90...Pump, 78.91...Heat exchanger, 80.94...pH measuring device. Representative Patent Attorney Gen Imamura 1<r ri'r Agency Director Shiga et al. 1. Things are good! 1
Indication of 1984 Tokudoro'1 Application No. 9845362, Title of the Invention A method for extracting zinc by electrolysis, especially a method for treating an umbarge solution 3.7 Famous works of Ichimasa! 1.Relationship Patent Applicant Name: Mineme Roussie 1Russ (lL#XJSuno4, Agent: 1-1-14 Shinjuku, Shinjuku-ku, Tokyo);
El (zip code 160) Telephone (03) 3!14-16
゜Supplement■ Number of inventions increased (contents (, 2 unchanged)

Claims (9)

[Claims] (1) A method for preparing a purified solution during electrolytic extraction of an aqueous solution containing a high concentration of a salt of a recoverable metal, the method comprising: forming a catholyte by supplying an aqueous solution containing a salt of a recoverable metal to an anode compartment containing an anode of the electrolyzer; The anolyte is separated from the anolyte by an anion exchange membrane, and recoverable metals are extracted from the catholyte by electrolysis, and the recoverable metals are deposited on the cathode of an electrolyzer.
1. Extracting anions from the Ka-F solution by electrodialysis,
The anions are transferred from the catholyte to the anolyte through the anion exchange membrane, and the concentration of acid in the anolyte is maintained below 0.5N to increase the efficiency of the anion exchange membrane. It is characterized by adjusting the flow rate of the anolyte through the anode chamber. (2) The method according to claim 1, further comprising controlling the temperature of the catholyte. (3) The method according to claim 2, further comprising controlling the temperature of the anolyte. (4) The method according to claim 1, further comprising circulating the anolyte into the anode chamber. (5) The method according to claim 1, further comprising treating the catholyte after extracting the recoverable metal. (6) The recoverable metal is zinc, and the aqueous solution of the salt of the recoverable metal is a purified neutralized solution of zinc sulfate having a pH of more than 1.5. The method described in Scope No. 1. (7) The method according to claim 6, wherein the aqueous solution is extracted using a cascade electrolyzer. (8) The method of treating a catholyte comprises neutralizing the catholyte with a base to separate the catholyte into a basic zinc salt and a liquid effluent, and returning said basic zinc salt to an extraction stage. Claim 7, characterized in that
The method described in section. (9) further neutralizing the liquid effluent to a pH of about 11;
separating a precipitate containing magnesium and manganese formed during the neutralization step of the liquid effluent; further selectively precipitating manganese after oxidation to manganese dioxide;
9. The method of claim 8, comprising separating the manganese dioxide and neutralizing the liquid effluent with sodium hydroxide at a pH of about 11 to remove magnesium. 7. The method of claim 6, wherein the αD catholyte has a zinc sulfate concentration that is much lower than the zinc sulfate concentration of the n solution. α2 The method of claim 1 further comprising circulating the anolyte and catholyte separately in a closed path. 03. The method of claim 6, further comprising recycling a portion of the anolyte withdrawn during the electrolytic extraction of zinc. (+41) A process for the electrolytic extraction of zinc, comprising leaching a torrefied sulfide ore to form a raw leaching solution enriched in zinc sulfate, and purifying the raw leaching solution to form a purified solution enriched in zinc sulfate. adding the purified solution to a cathode chamber containing a cathode of an electrolyzer to form a catholyte solution, and extracting the catholyte by electrolysis to form a zinc deposit on the cathode of the electrolyzer. and forming a cathode solution reduced in zinc sulfate;
The purified solution is added to a seven-node chamber containing an anode of an electrolyzer to form an anode solution, and the cathode solution and the anode solution are separated by an anion exchange membrane. The anions are transferred from the cathode solution to the 7nor solution through the anion exchange membrane, and the acid concentration in the anolyte is 0,
Adjust the flow rate of the anolyte through the anode so that it is below 5N, and recirculate a portion of the catholyte to the leaching step. neutralizing a portion of the cathode solution to remove unseparated impurities such that the concentration of the unseparated impurities in the portion of the cathode solution does not exceed a predetermined threshold; Said method comprising recycling a portion of the solution into the seven node chamber of the electrolyzer. α4 A part of the purified solution is transferred to a cathode chamber, another part is transferred to a 7 No-P chamber, and the part transferred to the cathode chamber is mixed with a part of the solution in which zinc sulfate has been reduced. A method according to claim 14. (161) A method of fixing a selectively permeable heterogeneous membrane having a substrate and a coating, moistening the membrane, applying the nuclear membrane to the seal to form a closed loop, and forming a closed loop between the nuclei. Dry the portion of the membrane outside the seal bounding the loops, leave the portion of the membrane that rests on the inside of the seal moist, peel the substrate from the dry portion of the membrane, and remove the substrate from the dry portion of the membrane. A method as described above, consisting of gluing the dry part of the membrane onto the branch body.