DE2508094A1 - PROCESS AND DEVICE FOR ELECTROLYTIC SEPARATION OF METALS - Google Patents

Description

Dipl.-Ing. Hi MITSCHERLICH D-8 MONKS 22

r »· ι ι tr r ~ i iki £? / - * i_ilj Λ κικι S'einsdorfslraBe 10

D, pl.-ln ₉ . K. GUNSCHMANN »". ""

Dr. r.f. not. W. KÖRBER Dipl.-Ing. J. SCHMIDT-EVERS

PATENT LAWYERS

February 25, 1975 KENEEOOTT COPPER CORPORATION

Eaat 42nd Street 9R08Q9A

New York, Ν.Ϊ., Y.St.A.

Patent application

Method and device for the electrolytic deposition of metals

The invention relates to "methods and devices for electrical deposition of metals, especially copper, which occurs both in electrolytic metal extraction as also prove to be beneficial in electrical refining.

According to the invention, it is possible to have a high current density when iwetall is deposited on a cathode work. In this context, the term "current density" means the ratio between those measured in amperes Amperage and the cathode area, usually measured in square decimeters.

In the previously known methods for electrolytic metal extraction, a current density is usually used

ρ
worked from about 2.26 A / dm. While it is of course known in the art that increasing the current density results in a decrease in the time it takes to deposit a given amount of copper, it would appear to those skilled in the art that the main obstacle to increasing the current density which is necessary is to increase the current density The fact that no suitable means of generating convection currents to move the electrolyte was available. The invention has now created methods and devices in which convection currents occur

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in such a way that it is possible to control the current density in an electrodeposition process to increase, while at the same time the expected increase in the consumption of electrical energy as possible is kept low.

A main advantage that can be experienced with the help of the ^ and Can achieve devices according to the invention, consists in avoiding electrical short circuits by a Contact between anodes and cathodes can be brought about. This reduces to a considerable extent the up to now required effort to locate and eliminate such short circuits.

First of all, it should be noted that the induction of gas movement in an electrolytic process to obtain Metal as such is not new. In fact, it is with electrolytic deposition of copper from acidic solutions known, the electrolyte in particular in the area to keep the anode surfaces constantly in motion. This movement is up to now with the help of a mixture of gaseous Sulfur dioxide and steam. The use of steam is used to maintain the correct temperature conditions. The pipes through which the mixture of steam and sulfur dioxide is passed have openings or nozzles, which are each arranged at such an angle that the escaping mixture of gas and steam hits the anode surfaces at an angle so that the Electrolyte is constantly circulated and a maximum movement of the electrolyte with respect to the anode surfaces is caused. Also when depositing copper is the use of a mixture of steam and a gas to move the electrolyte known.

By and large, however, the methods known up to now for moving the electrolyte do not make it possible bring about sufficient convection movement of the electrolyte, which would allow the current density in to a considerable extent and thereby the

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Accelerate production of high quality copper or other metals. You can also use the ones known up to now Do not use the method for moving the electrolyte during the electrorefining, as in this case anode slime is suspended, whereby the quality of the deposited ■ metal is impaired.

In the previously known methods in which cathode blanks are used without holding action, the tapes Cathode blanks covered with a non-conductive or an insulating material to prevent them from becoming the metal surfaces deposited on both cathode surfaces unite with each other because such a union would make it difficult to remove the precipitate from the cathode. An important additional advantage of the convection arrangement according to the invention is that it is not required is to provide the cathodes with an insulating surround in order to obtain a cathode without holding effect, in which a union of the edges of the precipitation on both flat sides is prevented.

Another important advantage offered by the invention is the fact that the cathodes are guided by guide means be brought into the correct position, and that after the introduction of the cathodes into the cells, the emergence electrical contact between anodes and cathodes is avoided.

The invention is therefore based on the object of methods and devices for the electrolytic deposition of To create metal in which it is possible to work with values of the current density which are compared to the concentration of the metal can be said to be high, and where it is possible to find a metal of useful unity and sufficient mechanical cohesion. The invention is also intended to create methods and devices which make it possible during an electrolytic deposition process to bring about a vigorous movement of the electrolyte, which in particular allow copper to get in the way

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of electric refining, and which also make it possible to To extract copper electrolytically.

In order to achieve the stated object, an electrolytic deposition cell has been created by the invention, the at least two mutually parallel, separated by a distance anodes and cathodes, which are in one Electrolyte are located, as well as a device for moving the electrolyte with the aid of gas; the cell has electrical non-conductive guide elements, which are arranged along the side edges of the anodes, and an electrically non-conductive chewing part disposed along the lower edge of the anode; to the device for moving the electrolyte with The help of gas includes a device for creating a curtain, which consists of rising gas bubbles and itself continues to move upwards from a point below the flat sides of the cathodes along these flat sides means are provided by which the anodes and cathodes are kept at small distances from one another ^ In this case, the lateral guide elements and the electrically non-conductive component at the lower end of the anode form enclosures between the cathode and anode surfaces, which are used for lateral expansion and contraction to limit the curtain formed by the bubbles as much as possible and thereby the deposition of metal on the cathode bands protruding beyond the guide elements to prevent.

The invention also provides a method for the electrowinning of metal on a cathode which includes measures to apply an electrical potential to an electrodeposition cell, which includes at least one pair of parallel spaced apart anodes and cathodes which are mutually aligned are in an electrolyte to maintain a current density sufficient to pass metal ions through the To transport electrolyte through it so that it is deposited on the cathode and accumulates around the electrolyte

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to keep moving with the help of a gas, as well as in accordance with of the invention to maintain a small distance between the flat sides of the anodes and cathodes to allow movement to cause the electrolyte in that a curtain of rising gas bubbles is generated, which are from a Move the point below the cathodes through the electrolyte and over the flat sides of the cathodes, and to restrict the flow of the rising curtain of gas bubbles to a predetermined path passing through the Guide organs assigned to anodes are determined, so that a lateral spreading and a contraction of the gas bubble curtain Avoided as much as possible and the precipitation of metal on the lateral and lower bands of the cathode surfaces prevented will.

Finally, the invention provides an anode for use in an electrowinning cell has been created, which has a piece of sheet material made of a metal or a metal alloy, on which Lateral edges guide organs are attached, which consist of an electrically non-conductive material, as well as a made of an electrically non-conductive material, which is attached to the lower hand of the anode so that it forms an extension of the anode.

The convection device according to the invention is a combination of which convection is produced Include guide elements and cathode guides attached to the anodes or located in the container, maintaining predetermined small distances between the cathodes and the anodes, as well as one below the Cathode and anode of a pair and means arranged therebetween for generating gas bubbles, by means of which the Electrolyte is kept moving. With this arrangement, it is possible to significantly increase the current density while at the same time it is possible to get by with a lower energy consumption, whereby high-quality metal is obtained can be. Since cathodes are used according to the invention which have no holding effect, it is not necessary

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to use so-called mother plates. The important economic ones Advantages of the invention are that it is possible to reduce the size of the plant that the Reduced maintenance costs, and that you get by with a lower consumption of energy and metal.

The invention and advantageous details of the invention are described below with reference to schematic drawings explained in more detail using exemplary embodiments. It shows:

Fig. 1 is a view of a formed in a known manner, no holding effect exerting cathode blank, in which the side edges are provided with an insulating border;

2 shows a perspective illustration of a cathode blank which does not exert a holding effect, in which on each A layer of copper is applied to the flat side;

FIG. 3 is a shortened section along the line 3-3 in FIG. 2; FIG.

Fig. 4- is a perspective view of a none A cathode with a holding effect in connection with bubble pipes to create fluidized curtains from gas bubbles near both flat sides of the cathode;

5 is an enlarged, exploded perspective view Representation of a cathode terminal of the type also shown in FIG., As it is only at very high values of the current density is needed;

Fig. 6 is a perspective view of a cord of a cell with an insoluble anode that electrically insulating guide elements are assigned as an extension of the lower end and on the long sides;

Fig. 7 is an exploded perspective view an anode clip particularly suitable for use in conjunction with cast soluble anodes when in the electro refining with a very

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high current density is worked;

Fig. 8 is an foreshortened view of the assembly of Fig. 6 as viewed from line 8-8 in Fig. 6;

Fig. 9 is an enlarged section taken along line 9-9 in Fig. 6; and

FIG. 10 is a perspective partial illustration of FIG a support built-in bubble pipes.

The invention provides methods and devices which make it possible to produce cathode metal of excellent quality from all common electrolytes to be deposited, including those in which sulfuric acid is present in high concentration. The device according to the invention can be used in connection with various anode materials. For example, at the device anodes made of lead antimony can be used. The cathode can be a mother plate or none Acting cathode blank exerting a holding effect, which is made, for example, of stainless steel or titanium.

Although it is possible to use a mother sheet as a cathode, in an important embodiment of the Invention uses an elongated, no holding effect exerting cathode blank. In this context it should be noted that although it is known to use Kohlinge, which do not cause a holding effect, but that according to the previous one Prior art in these cathode blanks difficulties arise from the fact that the edges of the blanks with a insulating material must be covered to prevent the deposited on both flat sides Unite metal surfaces so that the removal of the deposited metal is not made difficult.

Fig. 1 shows a trained in a known manner, Cathode blank 10 which does not exert a holding effect and which is immersed in an electrolyte 12. For the sake of clarity

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are in Pig. 1, the anodes and the other ^lj -eile not shown, which are used for depositing metal on a cathode normally required. If no holding effect is used cathodes, the deposited metal is removed after the completion of the deposition process. In order to make this possible, it is important to ensure that the metal layers which are deposited on the two flat sides of the cathode do not unite with one another in the region of the longitudinal edges of the cathode. In order to prevent such a combination of the metal layers 14 and 15 (Fig. 3) over the longitudinal edges of the cathode, the longitudinal edges of the cathode blank 10 are provided with insulating bezels 16 so that no metal is deposited on the cathode in the area of these bezels . According to FIGS. 2 and 3, after the edges 16 have been removed, a cathode 10 is obtained, on which there are two layers 14 and 15 of deposited metal.

If one uses a device according to the invention, one does not need the cathode with bezels of the type described to provide, but you still get two metal layers on the flat sides of the cathode blank, which in Fig. 2 and 3 shown are similar. In a device according to the invention for the electrolytic extraction of metal, the electrolytic deposition of metal on the hands of the cathode blank under the surface of the electrolyte according to FIG 6 thereby prevents the longitudinal edges of the insoluble anode from being provided with insulating convection guides 18 and that an insulating extension 20 is attached to the lower end of the anode. The length of the in. The electrolyte Immersed cathode blank is expediently chosen so that it is equal to the length of the submerged part of the Anode and its lower extension or slightly greater than this length, as shown in FIG.

In the case of electrorefining, the anode extension is on the bottom of the container and the anode is above the extension arranged. In the case of an electrical refining cell, the lateral guide elements can be arranged on a support

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and in the same way in the correct position to the soluble anode The side baffles 18 and the lower extension 20 for insoluble anodes are best from i'ig. 6 and 9 can be seen. On the way in which the lateral guide members 18 and the lower extension 20 the Prevent the deposition of copper on the strips of the cathode and an undesired deflection of the rising bubbles, will be discussed in more detail below.

. 4 shows a perspective view of a cathode blank 22 which does not exert any aging effect, as it is in accordance with the invention lets use. It is convenient to manufacture the cathode 22 of 316 stainless steel so that it has a rolled surface in accordance with delivery specification 2B, if this material is used, one is not necessary Pretreatment of the cathode, or it is not necessary to provide a start-up time. In addition, the rainfall from such a cathode blank easily peel off by hand, in fact the precipitates easily peel off the cathodes 22 once the upper bands of the precipitates have been loosened, furthermore it is possible to remove the precipitates to separate the cathodes from the cathodes by bending them. It should be noted, however, that the cathode blanks 22 can also be made from other materials. For example, it has been shown that in the method according to the invention Allow hollow rings made of titanium to be used advantageously, furthermore it is possible to use flat material pieces made of other conductive materials as cathode support, their selection depending on the type of metal to be deposited and the Composition of the electrolyte is aimed.

If the current-carrying capacity of the contacts between the usual busbars of triangular cross-section and the electrode suspension rails is to be exceeded, it has proven to be useful to reduce the contact resistance by using contact clamps of the type shown in FIGS with a very high current density. In I ¹ Xg. 4, a cathode suspension rail 24 is shown attached to a

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End is provided with such a clamp; depending on the In addition to the current density and the type of conduction of the Stx'om between adjacent cells, one can if necessary manage without such terminals or use one or two such contact terminals for each electrode.

An arrangement is often used to suspend insoluble anodes similar to that according to Fig. 1, 2 and 4 are used, in which each anode is clamped between two Iragschienen. Fig. 6 and δ show a further common device for hanging an insoluble anode, which with two cast, vertically upwardly projecting lugs 26 is provided, of which parts of a suspension usually made of copper are enclosed by a rectangular cross-section. According to the invention, however, the arrangement according to 1, 2 and 4 are preferred, since in this case it is possible to move the anode surface closer to the cathode surface. In any case, it is possible as required, with insoluble ones Arrange to use contact clips of the type shown in Fig. 5,

Soluble anodes, such as those used in electro refining are usually cast and have outwardly protruding lugs with a non-rectangular cross-section on. The contact terminal shown in Fig. 7 was developed for use in the method according to the invention, in which an electrorefining is carried out at a very high current density. In general, such con-

Clock terminals are superfluous at current density values of about 6.45 A / dm, but their use is at a current density of

ο
about 10.75 A / dm or more is highly recommended. The contact clips used in production could alternatively be designed so that they have cams or the like actuated by weights so that they do not have to be attached to the anodes by hand.

6 shows in perspective an anode 50 which can be used according to the invention, which in a typical case consists of a Lead-antimony alloy. It should be noted, however, that the material from which the anodes are made

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does not form an object of the invention. In the embodiment for electrolytic metal extraction, the anodes can consist of any material, the suitable electrochemical and has mechanical properties. To get out of the To get the maximum benefit from the invention, it is of course expedient to design the anodes so that they are rigid and have a uniform cross-section. According to FIGS. 8 and 8, each anode 30 is provided with numerous openings 52. These square openings are a design feature of every high quality insoluble anode, as known on Way to be used in the electrolytic production of copper, but they offer in the movement according to the invention of the electrolyte with the help of gas bubbles have no particular advantages.

An important feature of the anodes of the invention is there that on them according to FIG. 6 guide members 18 and extensions 20 are attached, all of which are electrical are insulating or non-conductive. The guide organs and extensions can be made of any electrically non-conductive Material that is found to be relatively stable in the electrolyte. For example, there were such extensions and guide elements made of a polyvinyl chloride polymer, which in the present case is more suitable than other insulating materials such as polyethylene, polypropylene and panels made of glass fiber reinforced Epoxy resin.

According to FIG. 9, the side organs 18 delimit narrow ones Channels through which the longitudinal edges of the cathode blanks 22 extend.

Every person skilled in the art is familiar with the fact that there is only metal on the flat sides of elongated cathode blanks deposited to lines that run a small distance below the lower edges of the anodes. Also will no metal is deposited on the flat sides of the cathode blanks where the cathodes are over the edges of the

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Guide organs 18 extend away to the outside because of these If there is an increased electrical resistance. Thus, the convection control organs 18 also act as shields for the electrolyte flows to the effect. Is of the extensions 20 and the working organs 18 on the anodes or with a corresponding arrangement for the electrical refining If used, one is created on each side of the pool Cathode, which is similar to that according to FIG. 1, but has no bezels, a copper layer, as shown in FIG. and 3 is shown. Limiting the spread of the precipitate to the barely within the edges of the cathode surfaces offers significant advantages; Firstly, there is no need for time-consuming maintenance and renewal of the insulating edging, second, removal of the precipitates from the cathode blanks is facilitated; and thirdly, it becomes a Source of contamination eliminated, namely the formation of a bead composed of knots, such as it usually develops at every edge. A Another advantage of the Randleitorgane according to the invention is that when the anodes are already in the Cell, the cathodes are exactly in the correct position with respect to the anodes and the Whirlpool pipes are guided.

With the soluble anodes used in electrorefining, it is usually not practical to to attach the convection guides to the anodes. In this lall, good results can be achieved equally, if the lateral guide organs are arranged in supports that run along the relevant walls of the refining cell extend. It should be noted in particular that it is with the help of a method and a device was possible according to the invention, an electrorefining of

Copper at a current density of up to about 22.57 A / dm to be carried out, i.e. at a value that exceeds the normal value by ten times, without passivation the anodes entered. In current practice, passivation of the soluble anodes normally prevents the electro refining with high values of the current density.

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As mentioned, there are important features of the process and the device according to the invention, which make it possible to work with a high current density, in the reduction of the Electrode spacing and the use of a novel arrangement to induce convection. In the invention Device, the convection of the electrolyte is brought about that the electrolyte with the help of gas is moved. In the field of electrodeposition the use of gas to move the electrolyte is known. According to the invention: however, the means for inducing convection produces a fluidized curtain relatively small, rapidly rising gas bubbles which, together with the turbulence they cause, form a powerful Carry out mixing at the cathode surface where such mixing is most needed. This arrangement to induce convection ensures that optimal conditions exist for the separation process in such a way that that the cathode remains smooth and void-free during all stages of its growth.

The movement of the electrolyte through the gas creates convection sufficient to prevent it from occurring settle suspended particles on the cathode surfaces. Furthermore, in this arrangement to induce convection there are no obstacles in the flow path of the electrolyte along the cathode surfaces, and the cathode surfaces are free from physical discontinuities, e.g. from borders and loops, which could lead to the trapping and accumulation of solids. These characteristics prove to be are particularly advantageous in electrical refining, because there is a large amount of anodic mucus in the cell develop. In contrast to the prior art, it has been shown according to the invention that it it is possible to shift anode slimes to a considerable extent without this leading to that on the cathodes precipitated material absorbs impurities to a greater extent. However, in order to achieve this effect the convection currents will be exceptionally strong, and

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the presence of physical obstacles must be avoided; these requirements are met by the invention. In a corresponding manner, the invention prevents the electrolytic metal extraction that the recovered metal picks up particulate impurities, as they are in a Corrosion or erosion of the insoluble anodes occurs. For example, it has been found possible to use electrolytic Ways to obtain copper of exceptional purity, with anodes of known types made of lead or lead alloys used in electrolytes that attack these anode materials.

As shown in Fig. 9, the small bubbles 50 are attached to the electrolyte 12 discharged through jets 52, which are below the Electrodes 30 and 22 are arranged in the cell containers. The air throughput of the whirlpool pipes does not need to be large. With a whirlpool tube made of stainless steel with a Outside diameter of about 9 »5 mm and a wall thickness of about 0.51 mm, a suitable opening diameter is about 0.15 mm if the openings are at intervals of about 12.7 mm are distributed. However, it is also possible to use a less convenient bubble tube arrangement if one a smaller increase in the current density and the quality of the deposited metal is sought.

In the most expedient arrangement, each bubble tube 52 is designed as a rigid tube that is spaced apart by about 12.7 mm. is provided with round openings, the diameter of which ranges from about 0.13 to 0.18 mm. It has been found that with bubble pipes where the openings have a smaller diameter of, for example, about 0.1 mm, no better effect can be achieved, but that it it is more difficult to manufacture such pipes. Furthermore, it has been shown that bubble pipes with larger openings, the e.g. have a diameter of about 0.23 mm, emit unnecessarily large amounts of gas, or that a comparable volume of gas is released at a lower velocity of the gas bubbles. See Fig. 9 for each cathode on each Side a bubble pipe 52 in front, is an appropriate air

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throughput ranges from about 280 to 370 standard liters each Hour and meter cathode width or more in the case of cathodes Size in the range of about 4-55 to 610 normal liters per hour and square meters. This volume of throughput is equivalent to the rate at which oxygen passes through an insoluble anode at an anode current density of approximately 14.5 to 19 »55 A / dm is produced. It has been found that the volume of air released is not so important as the overall design of the bubble tube and electrode assembly when the electrolyte is in the desired manner with the help of Gas is to be moved. The lack of this knowledge has presumably led to the further introduction of the "use of gas for Moving the electrolyte in large systems for electrolytic deposition is delayed

Although already nitrogen was used to move the electrolyte, but the ^U SE of air is always preferred for reasons of economy, when the supply of atmospheric oxygen appears as permissible. If air is used in the right way to move the electrolyte, this measure, in contrast to other known and customary methods of inducing convection, proves to be more effective than less when the distance between the electrode surfaces is reduced.

In order to prevent the openings of the whirlpool tubes 52 from being encrusted by dissolved substances that have solidified the air supplied is previously saturated with water vapor, the temperature of which is almost the same as the temperature of the Electrolytes is «If this measure is used, the bubble tubes can be practically operated for an unlimited period of time use without clogging the openings.

Finally, it is provided according to the invention that the distance between the electrodes is made so small that as it is practically possible, taking into account the dimensions of the electrode supports and the space that is required for inserting and removing the cathodes. In

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Combination with the movement of the electrolyte through gas bubbles enables the electrode spacing to be reduced, in electrolytic metal extraction or in electrorefining reduce energy consumption to a minimum. The reduced electrode spacings are according to Fig. 9 maintained by lower brackets 54- supported by Cross members 58 are interconnected. On the cross members 58 supports 60 are attached, through which the lower Brackets 54- at the desired height above the bottom of the oiler Cell to be held. Of course it is necessary to have enough on all sides of the cell and in its lower part Provide free space so that the electrolyte can circulate and any mucus that may develop is able to settle.

The lower edges of the cathodes 22 are placed in the electrowinning tank through the bubble tubes 52 load-bearing supports 56 held in place, and upon insertion, the cathodes are passed through the edge guides 18 of the anodes. The anodes and the guiding organs serve at the same time to force the gas bubbles 50 to upwards within that part of the electrolyte move, which is immediately adjacent to the cathode surfaces, in order to thereby achieve the required concentration depolarization to effect and to achieve a uniform mass transport of metal ions to the cathodes. The distances between the cathode blanks or mother sheets and the insulating edge guides of the anodes are of the order of magnitude from 1.6 to 3.2 mm.

The method according to the invention for moving the electrolyte with the aid of gas also offers advantages with regard to the anode reaction. In particular, in the case of electrorefining, not only is passivation of the anodes completely prevented, but it is also achieved that the soluble anodes are attacked evenly, so that the accumulation of anode scrap is reduced. E _r heightening the efficiency can be achieved further characterized in that soluble anodes with uniform cross-section instead of the

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common, somewhat irregular cast anodes are used.

The extensions 20 at the lower land of the anodes 30 that are also made of an insulating material, serve to hold together in their lower -eilen ^Ij the air bubble curtains and to determine the position of the anodes. Each anode 30 is supported by associated lower brackets 54- in Pig. 9 clearly kept in their position. The or each bubble tube 52 is arranged deeper than the adjacent cathode surface in its row and is moved by 'iragstück 56 towards iig. 9 and 10 supported. In the case of soluble anodes, it is usually not practical to attach an insulating extension to the lower end of each anode. In this case, the lower end of each anode can be inserted into associated lower holders, and the components arranged vertically can be used for this purpose or covering brackets 54 with an electrically insulating material.Alternatively, insulating tabs 20 may be inserted into the lower brackets 54 so that their upper edges come into contact with or are in proximity to the lower ends of the soluble anodes.

The main reason for working with electrolytic metal extraction or electrorefining strives for a high current density, is that it is hereby possible to reduce the dimensions of the system, get by with a smaller amount of metal and reduce the workload. Another advantage it results from the fact that certain known process steps, which include the production of mother plates, are superfluous and the elimination of short circuits. Shall take advantage of electrolytic deposition at high current density are fully utilized, but it is necessary to carry out the process using currents, which are considerably less than the current density causing a limitation, and the energy consumption to one To decrease the minimum. By 'the invention, a combination of measures has been created which are suitable

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to meet the conditions mentioned by the fact that the distances be reduced in size between the electrodes and that some means for moving the electrolyte are used, which ensures that a sufficient amount of metal ions is supplied to all parts of each cathode surface. the Movement of the electrolyte offers the additional advantage that the electrolyte bath is sufficiently mixed so that suspended partially serpentine "impurities prevented from doing so will adhere to the cathode surfaces and that therefore higher quality precipitates can be produced.

During electrolytic mining, fine oxygen bubbles formed by the insoluble anodes which the concentration potential at the anodes is reduced, but which are not sufficient, a thorough mixing at the to cause opposite cathode, even with a small electrode spacing. The reason for this is in that the small oxygen bubbles float around ineffectively because of their small size. Therefore it is necessary to bring about a movement of the electrolyte at the anodes in another way, in particular in the case of a high current density bring about a sufficient depolarization of the cathodes. It has been shown that the inventive Using gas to move the electrolyte in a desired way leads to an increase in the depolarization of the cathodes, when reducing the electrode gaps; this applies at least within certain limits. With small gaps separate electrodes of the commercial size can The movement of the electrolyte through gas will prove to be the only useful means of ensuring sufficient mass transport caused over the entire cathode surfaces when working with a high current density.

The arrangement according to the invention for moving the electrolyte with the help of gas leads to a considerable flow movement of the electrolyte and to the maintenance of a uniform composition of the electrolyte within all parts of the electrolytic cell when that cell is in dimensions within reasonable limits. Indeed

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the composition of the electrolyte both within the cell and in the overflowing material is substantial the same.

The preferred embodiment of an arrangement according to the invention for inducing convection is shown in FIG. 9 shown, where you can see that the lower brackets 54-, the Anodes JO with their lower extensions 20 and the guide members 18 attached to their lateral bands in connection with the elongated cathode blanks 22 form enclosures through which a lateral expansion or contraction the gas bubble curtains are reduced to a minimum. It is true that differently shaped support members could also be used in the container use to hold the gas bubble curtains together, but it has been found that that described above Arrangement proves to be highly effective and expedient, as it considerably facilitates the insertion and removal of the cathodes, and the creation of short circuits as a result of misalignment to warping and bending is practical is turned off.

Of course, the whirlpool pipes could also be designed differently. For example, gas bubbles can be used in a premix with the re-circulated electrolyte and transfer the mixture of gas bubbles and electrolyte into the container introduce a source which occupies approximately the same position as each of the air bubble tubes 52 of FIG. 9 in this In this case, the dimensions of the bubble tubes can vary, and the dispensing openings can be enlarged to accommodate that A sufficient amount of the circulated electrolyte escapes and to allow an appropriate amount of entrained gas.

The decisive criterion for the design of the device for moving the electrolyte is that the apparatus must be capable of small ^u asblasen dispense by means of a line that is immediately adjacent to the cathode surfaces so that curtains are produced from fast-rising bubbles which in the immediate is vicinity

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move the i-athodenal surfaces further in a certain direction, until they reach the surface of the electrolyte. The invention was applied to relatively pure electrolytes, e.g. in the case of extraction using ion exchange in a liquid or in production can be used by mother plates, as well as with relatively heavily contaminated electrolytes, such as those caused by the flushing currents are formed during the electrorefining or arise in various processes for leaching ores.

The advantages of the invention are even more evident when dealing with impure electrolytes which normally make up a pure metal with a low ratio between the metal concentration and the current density does not allow to gain. In the normal electrolytic extraction of copper in vats leaching solutions used becomes e.g. the lower limit for obtaining useful precipitates at a ratio of about 0.16 between that given in grams Amount of copper per liter and that in amperes per square decimeter specified current density is reached because of the increase in the viscosity of the electrolyte and the resultant Reduction of the mass transport coefficient of the divalent copper ions, which in turn can be attributed to it is that dissolved foreign matter in a significant concentration available.

The features of the invention, i.e. the reduction in the distance between the electrodes as well as the strong and uniform loading movement of the electrolyte, make it possible to carry out electrolytic metal extraction in an economical manner at a high Perform current density, which is still significantly below the limit value of the current density, which for certain mass transport conditions is applicable. The results are quite acceptable. Dense and coherent cathode products can still be achieved regardless of the composition of the electrolyte if one considers the value of the ratio

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between the copper concentration and the current density is reduced to about 0.02 to 0.03, furthermore the avoidance of the Use of mother sheets and separating agents, which are achieved by using cathode blanks that do not have a holding effect is made possible, as well as the regulation of the distribution of the current density in such a way that the tapes of the cathodes do not need to be covered, for the formation of deposits, which in all of its parts, including the marginal areas, have an excellent - ^ unity. In particular, it is possible reduce lead pollution to about 0.1 ppm and sulfur pollution to about 2.0 ppm.

The following examples make this even clearer recognize extreme conditions regarding the contamination of the electrolyte and the low concentration of metal ions, among which, according to the invention, it is possible to carry out electrolytic metal extraction at high current density .

The numerical results, which apply to Examples 1 to 4 below, are given in Table I below summarized.

example 1

This example is a typical one Case where the electrolytic metallurgy was carried out with high acidity and high current density. Of the The distance between the cathodes and the anodes was set to be about 32 mm. The copper and specified in Table I Acid concentrations apply to the contents of the cell and not to the electrolyte supplied to the cell. the Ivienge of the suspended material became with constant stoop circulation and filtration kept as low as possible. The movement of the electrolyte was made using that in the drawing shown device brought about; for this purpose, whirlpool pipes made of stainless steel with an outer diameter were used of about 9.5 now and a wall thickness of about 0.51 mm, which are provided with openings at intervals of about 12.7 mm whose diameter was about 0.15 mm. the

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_ 22 -

supplied air was characterized presaturated with water, and they were passed through hot »» ater, and the air was supplied in a narrow ^ from about 304 normal liters per hour per square meter of the -athodenf ^is laughing. In this ^v beseech a mother plate made of copper was used as the cathode, and in conjunction with a conventional anode made of a lead-antimony alloy.

The results which can be seen from Table I show that there is a good precipitate with a current efficiency of 97% was achieved even though the ratio between the copper concentration and the current density was about 6.6, i.e. about twice as much as with the commercially available electrolytic Extraction of copper. The level of impurities was very low. The high current efficiency achieved in this experiment is typical of the results obtained in the examples described below.

Example 2

In this example, the influence of liquid ion exchange media as impurities was examined. The electrolyte purposely saturated with a liquid ion exchange agent and petroleum to mimic the impurities, which can get into the container for the electrolytic metal extraction if before the electrolysis one Ion exchange is carried out. In addition, the contaminated electrolyte was not filtered in order to remove the to avoid entrained organic phase. Table I indicates that the presence of the organic impurities did not affect the results previously obtained. The copper concentration in this case was 29.5 s / l

ο reduced while a current density of about 6.45 A / dm was retained. The measured conductivity of the electrolyte was around for most of the high acid requests 0.54 S / cm.

Example 3

An extremely high current density was used in this experiment. To determine the limit value of the current density, which still has cathodes of usable quality

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No holding cathodes were used Made of stainless steel grade 316 used in an electrolyte with a medium copper concentration. the Copper sheets were at a within about 200 minutes

2
Current density of 15.16 A / dm brought to the strength of mother metal sheets. Precipitation was ductile but coarse-grained, and in some places the sulfur content was higher than before. The cell voltage and power consumption were kept within reasonable limits at this current density, and the amount of air supplied via the bubble tubes to move the electrolyte was increased to only about 395 normal liters per hour and square meter of the electrode surface.

Example 4

In this experiment, porous bubble tubes (Porous (Air EoIl) Bubbier) were used. The typical conditions with regard to the high current density according to Example 3 were retained, but under each cathode a porous Eohr arranged instead of a bubble tube. Excessive misting occurred on the electrolyte surface and the lead and sulfur contamination was higher than that of Example 3

The flow traces of the bubble streams were on the precipitate clearly visible and resulted in unevenness of the deposit on the cathode. Because of the poor mechanical cohesion of the precipitate turned out to be difficult to remove the precipitate from the cathode sheets to be deducted from stainless steel grade 316.

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Tabel I. 2 3 4th example 1 6.45 15.16 14.94 Current density, A / dm 6.34 27 26.4 19th Electrode spacing, mm 32 29.5 32 32 Ou concentration, g / l 42 172 171 171 Acid concentration, g / l 159 61 61 60 Temperature, G 60 2.3 2.8 2.5 Continuous voltage, V 2.3 1.96 2.35 2.13 Power consumption,
kWh / kg Cu 2.0 97 100 100 Cathode current
Efficiency, i ° 97 Impurity 0.7 0.7 1.1; 2.1 Lead, ppm 0.59 under 2.5 4.32 7.22 Sulfur, ppm under 3 4.5 13 35 Mucus, mg / l 0.9

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Example 5

This experiment was made with an electrolyte from leaching vats worked. The favorable results of the examples discussed above have been obtained when one electrowinning using a carried out relatively pure electrolyte, as it is referred to above as concentrate, which is when used of liquid ion exchange agents. When ore is leached, numerous foreign matter goes into the leach solution in addition to the desired metal-containing substances in solution. Often these are dissolved foreign matter to which Aluminum, magnesium and iron belong, present in such amounts that the mass transport conditions deteriorate so much, that it is not possible with the help of a direct electrodeposition, precipitates of high Achieve quality. In addition, if there are reducible solutes, e.g. ions from trivalent iron, in the electrolyte are present in a noticeable concentration, there is a considerable reduction in the current efficiency when the metal is deposited.

With the help of the methods and devices according to the invention, it has been shown to be possible on electrolytic Ways pure copper of sufficient mechanical cohesion from polluted electrolytes in leaching vats kind used to win. In addition, here was the relationship between the metal concentration and the current density many times lower than with the known processes, in which one usually has a product of less Quality is maintained. In this way of working it was possible to take advantage of the improvement in power efficiency to draw increasing current density; this can be seen from the values compiled in Table II. Both in these! "all the solutions used the content was present Aluminum. Iron and magnesium in the range of 10 to 20 g / l.

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Table II example

Current density, A / aar

2.15 3.22

Electrode spacing, mm 58.4 58.4

Cu concentration, g / l

Acid concentration, g / l

Cell voltage, V

Electricity consumption kWh / kg Cu

Mechanical cohesion

Current efficiency, i>

20th

49 52

Temperature, G

2.7 3.2

3.61 4.07

good Good

66

4.3

3.8

3.22 4.3

63 64

2.4

64 60

2.9

6.45

58.4 26.7 31.2 31.2

10.3 10.4 10.6

63 61

4.0

4.55 3.17 3.45

Sufficiently Sufficiently Sufficiently Sufficient

64

71

85

509835/0752

It is true that the examples discussed above relate on the electrolytic metal extraction, but it has been found that the arrangement according to the invention is capable of moving of the electrolyte with the help of ^ as also in electrorefining can apply. Bs has been shown to be possible, dense, mechanically perfect copper deposits of high Unity and very good appearance up to the strength of mother plates to produce on blanks without holding effect as well as on copper sheets that were treated with a release agent. It proved possible to get heavier rainfall of excellent quality and very good appearance, some of which weighed up to about 79.5 kg (on each Page) on mother sheets as well as on hollow rings made of stainless steel or titanium and also on other cathode materials to create. A passivation of the anodes was even carried out at

a current density of up to about 32.25 A / dm is not observed, and the precipitates were not contaminated by suspended anode slime.

In accordance with the invention, full size precipitates could be obtained compared to typical glee refined Copper is equal in terms of its contamination by lead, sulfur, oxygen and other substances or of higher quality, cathodic current efficiency values of over 95% could regularly be achieved if the electrolyte does not contain large amounts of reducible Contained impurities. Applying the teachings of the invention, numerous advantages can be achieved. One of these Advantages are that according to the invention it is possible to electrolysis from high acid content to more convenient ones Way to treat. It should be noted that it is known that anodes formed in a known manner from lead and lead_ Alloys are attacked by electrolytes with high acid content, i.e. when the electrolyte is sulfuric acid in an amount of over 100 g / l. Although the corrosion of the known anodes made of lead or lead alloys cannot be prevented, but the invention makes it possible to avoid that corrosion

509835/0752

products of the insoluble anodes are included. Although the invention is not limited to the use of Electrolytes with high acid content or lead-containing anodes, however, the invention allows among those mentioned here Conditions to achieve special advantages.

Another advantage of the invention is that electrolytes containing small amounts of copper are on can be processed economically. It should be noted that the ratio between the current in amperes per square foot and the copper concentration of grams per liter according to the invention can be up to 5, while this ratio according to the prior art is only 0.5 amounts to.

Although the use of lead-antimony anodes was mentioned above, it is within the reach of any person skilled in the art It is obvious that anodes made of any other suitable material could also be used. To the other usable Anodes include, for example, those made of lead or lead alloys, of titanium coated with precious metal oxides, and of Graphite. In fact, any insoluble or Use "dimensionally stable" anode. Of course, in electrorefining, one uses soluble anodes from the one to be refined Metal.

It is true that the use of will not have any holding effect Cathode blanks are preferred, but according to the invention it is also possible to use any other desired cathode supports to be used, e.g. mother sheets made of copper as well as blanks or sheets that are coated with release agents.

One of the most important advantages of the invention is that it is possible to use a high current density work and still achieve a high quality product. In fact, according to the invention, excellent

ο Results at a current density of up to about 32 A / dm achieve, which depends on the temperature and the composition of the electrolyte. In this context

509835/0752

it should be noted that anyone skilled in the art has up to now a current density of about 4.3 A / dm considered high; In comparison, it should be noted that the invention is advantageous

2 "wise for current density values between approx. 4.3 and approx. 32 A / dm can be used at a normal metal concentration in the electrolyte.

Another important advantage of the invention is that it is possible to reduce the distances between the flat sides of the anodes and cathodes to a value which is limited only by the dimensions of the supports, as is known, the resistance should be reduced in every respect to keep energy costs to a minimum. There are three measures available for this purpose, namely an increase in the 'J-' temperature, an increase in the concentration of the conductive dissolved substances in the electrolyte and a reduction in the distance between the electrodes electrode distances to considerable difficulties that are mainly due to a restriction of the convection according to the invention in an expedient manner for movement;. made of the electrolyte with the aid of kas, in contrast to the prior ^x reaches the technic that the convection so The smaller the distances between the cathode and anode surfaces, the smaller the distances between the cathode and anode surfaces, the reduction in these distances is limited by the design of the supports; usually it is not possible to reduce the electrode distances to less than about 12.7 mm. According to previous practice, the distance between the Ka method and anode areas usually at least about 32 mm.

! Of course, the invention is not limited to that electrolytic deposition of copper - Rather, it is possible to use the method and the device according to the invention very advantageously in the treatment of any metal, which can normally be deposited electrolytically from aqueous solutions. These include nickel, zinc and lead.

Claims: 509835/0752

Claims (24)

EXPECTATIONS 1. Electrolytic deposition cell with at least one Pair of anodes and cathodes arranged in parallel, separated by a distance and located in an electrolyte, and with a device for moving the electrolyte with the aid of gas, characterized in that that the cell has electrically non-conductive guide elements (18) which run along the side handles of the anodes (30) are arranged so that an electrically non-conductive component (20) is arranged along the lower edge of the or each anode is that the device for moving the electrolyte comprises a device (52) which is suitable, a curtain from rising gas bubbles opposite the flat sides of the cathodes (22), each curtain at one point is generated, which is lower than the lower edge of the cathode in question, and that means (54-) are present are that serve the anodes and cathodes at small intervals to keep from each other, said guide elements and the or each non-conductive component at the lower edge the anode in question each forms an enclosure between the cathode and anode surfaces in question, and wherein this enclosure prevents lateral spreading or contraction of the bubble curtains as much as possible, in order to prevent a deposit of metal on the edges of the cathodes, so that the deposits do not spread over the guiding organs extend beyond. 2. Cell according to claim 1, characterized in that the device for generating a At least one bubble tube (52) belongs to the curtain of rising gas bubbles, which is arranged lower than the associated one Cathode surface, and that is adjacent to the cathode surface, and that each bubble tube has a plurality of openings for discharge 809835/0752 of gas bubble streams. 3. Cell according to claim. 2, characterized in that the openings of each whirlpool tube (52) about 0.13 "to 0.18 mm in diameter, and that these openings are distributed at intervals of about 12.7 mm. 4. Cell according to one of claims 1 to 3 »characterized in that the means for maintaining a small distance between the anodes (30) and the cathodes (22) include lower supports (54 »58), which are arranged in the cell under the various anodes and are suitable for receiving the lower ends of the anodes, in order to determine the position of the anodes in relation to the cathodes. 5 · Cell according to one of claims 1 to 4, characterized marked that the band leading organs (18) extend substantially the entire length of each anode (30) and opposite the main plane of the relevant one The anode protrude in the direction of the adjacent cathode surface. 6. Cell according to one of claims 1 to 5 »characterized in that the non-conductive component (20) is attached to the lower hand of the associated anode (30) so that it forms an extension of the anode. 7. Cell according to claim 5 »characterized in that that the Randleitorgane (18) are attached to the side edges of the relevant anode (30). 8. Cell according to claim 5 »characterized in that that the Randleitorgane (18) from the relevant anode (30) separated and on a support in the cell are arranged at a fixed distance from the associated anode. 9. Cell according to claim 8, characterized in that that the non-conductive component (20) at the lower edge of the relevant anode (30) is separate from the anode 509835/0752 Has bag that is attached to the bottom of the cell so that it covers the lower hand of the anode. 10. Cell according to claim 2 and 4, characterized in that the bubble tubes (52) thereby in their are held in a fixed position with respect to the relevant cathode (22) so that they are built into associated support pieces (56), which in turn are connected to said holders (54) are. 11. Cell according to one of claims 1 to 10, characterized in that each cathode (22) as a cathode which does not have a holding effect is formed 12. Cell according to one of claims 1 to 7 »characterized in that each anode (30) consists of one material that is insoluble in the electrolyte. 13. Cell according to one of claims 1 to 12, characterized characterized in that the flat sides of the anodes (30) and the cathodes (22) are separated from one another by spacings which do not significantly exceed the dimension of about 32 mm. 14. Cell according to claim 10, characterized in that the lower end of each cathode (22) in support pieces (56) for the associated whirlpool pipes (52) is arranged to determine the position of the cathode relative to the adjacent anodes (30). 15 · Method for the electrolytic deposition of metal on a cathode with the aid of a cell according to one of the claims 1 to 14 with measures to apply an electrical potential to the electrodeposition cell to achieve a Maintain current density that is sufficient to transport metal ions through the electrolyte effect so that metal is deposited and collected on the cathode, and around the electrolyte with the help of a gas to move, characterized in that a small distance between the Ilachseiten of the anodes and the 509835/0752 Cathode is maintained that the electrolyte is moved by a curtain of rising gas bubbles is generated in the electrolyte at a point which is deeper than the anodes, such that the gas bubble curtains move over the i'lach sides of the cathodes, and that the flow movement of the rising gas bubble curtains is influenced so that the gas bubble curtains along a move predetermined path, which is determined by the guide elements that are associated with the anodes, so that a lateral Avoid spreading or contraction of the gas bubble curtains and the deposition of metal on the Long edges and the lower edges of the cathode is prevented. 16. The method according to claim 15 »characterized geke η η ζ eich η et # that the bubbles of the or each gas bubble curtain are composed of a mixture of air and water vapor. 17. Method according to claim 15 or 16, characterized in that the or each gas bubble curtain is generated by having gas in an amount of about 280 to 570 cormall liters per hour and meter cathode width is fed. 18. The method according to any one of claims 15 to 17 »thereby characterized in maintaining clearances of no more than about 32 mm between the anodes and the cathodes will. 19 · The method according to any one of claims I5 to 18, characterized characterized in that copper is obtained electrolytically from a relatively impure solution, such as it occurs when leaching ore containing metal. 20. The method of claim 15 characterized in that said metal is swab. 21. The method according to claim 19 and 20, characterized in that the solution per liter in each case 509835/0752 Contains 10 to 20 g of aluminum, iron and magnesium. 22. The method according to claim 21, characterized in that a current density of about 2.15 to about 4.3 A / dm is maintained. 23 · The method according to any one of claims 15 "to 18, characterized characterized in that copper is obtained electrolytically, and that between the copper concentration and maintaining a ratio of the current density substantially in the range of 0.2 to 0.7 grams Copper per liter to a current density of 1 ampere per square foot lies. 24. Anode for use in an electrodeposition cell according to claim 1, characterized in that an ilachmatenal piece made of a metal or a metal alloy is present, on whose side edges facing away from one another guide members (18) are attached are made of an electrically non-conductive material, and that a component (20) at the lower edge of the anode is fixed from an electrically non-conductive material so that it forms an extension of the anode. 25 · Anode according to claim 24, characterized in that the guide elements (18) are located on the longitudinal edges of the anode extend essentially over the entire length of the piece of flat material and opposite the main plane of the piece of flat material protrude outwards. de-attorney: 509835/0752