US2196355A - Means for circulating electrolyte in apparatus for the electrodeposition of metals - Google Patents

Description

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April 9, 1940. A- CREMER MEANS FOR CIRCULATING ELECTROLYTE IN APPARATU FOR THE ELECTRODEPOSITION 0F METALS Filed Dec. l, 1936 2 Sheets-Sheet 2 )91 creme Patented Apr. 9, 1940 MEANS FOR CIRCULATING ELECTROLYTE IN APPARATUS FOR THE ELECTRODEPO- SITION F METALS Alfred Cremer, Wolu Bel we-St.-Pierre, Brussels,

glllm Application December 1, 1936, Serial No. 113,690

In Belgium December 12, 1935 11 Claims.

My present invention relates to improvements in means for circulating solutions in apparatus for the electrodeposition of metals.

1t relates more particularly to means for obtaining, between closely spaced parallel electrodes immersed in one bath, a high rate of circulation of the electrolyte in a direction parallel to the surface of the electrodes, and for making said circulation` uniform over the whole of said surface.

It also has for its object to realise such high rate of circulation with the use of simple and cheap means.

Another object of my invention is to give a higher eiiicacy to and improve the output of the apparatus in accordance with Patent No. 1,466,- 994 granted to me on September 4, 1923. lIn this apparatus which comprises an elongated vat or channel the electrolyte circulation was facilitated to some extent by the arrangement of the electrodes which extended parallel to the channel.

However when seeking to obtain a high rate of circulation with this apparatus, difliculties were met on account of the large quantities of liquid to set in motion and on account of the high resistance encountered by the liquid current between the electrodes.

The present invention overcomes these diiiiculties and enables the electrolysis channel to be operated with high eiiiciency.

Various means have already been proposed in order to promote the circulation of solutions in electrolysis vats. Aside from well known pumps which may be used in connection with elevated containers, helical wheels or paddle wheels have been employed'which rotated in proximity to the electrodes and caused a general movement of the solution in the vat along a closed path passing between the electrodes. 'Ihese methods proved unsatisfactory as much energy was wasted in creating eddies; moreover the rate of circulation between the electrodes still was too low or lacked uniformity.

An essential object of my present invention is to provide a circulation that will be better guided,-

umore uniformly distributed between the electrodes and at the same time more active, especially when the electrodes lie very close to each other. 'I'he system according to this invention is based on the use of one or more injectors together with means o adapted to produce, guide and distribute a relatively strong current of solution between closely spaced parallel electrodes. The injectors are arranged in front of the groups of electrodes and they feed between the electrodes the requisite amount of electrolyte under high pressure. The electrolyte impelled between the electrodes and suitably guided-by conduits with successively converging and diverging walls, carries with it, by hydrodynamic action, a portion of the surrounding electrolyte.

The electrolyte injected under high pressure is supplied by a pump the suction side of which communicates as directly as possible with the down-stream side of the electrodes.

When a plurality of such groups of electrodes are mounted in series in a single trough-shaped vat forming a channel, only the portion of electrolyte carried between the electrodes by the hydrodynamic action of the injectors flows through the entirelength of the channel. This portion of the Aelectrolyte is returned through a passage on one side of or under the channel.

Under these conditions, with a comparatively small amount of solution forced through the injectors under a suitably high pressure, I am able to obtain between adjacent parallel electrodes much higher rates of circulation of electrolyte than those obtained with systems known heretofore. Such high rates of circulation necessarily are opposed by a high resistance to the flow between adjacent electrodes, and special means have to be provided in order to keep up a suitable pressure between the electrodes. This pressure in the present case results from the injection itself; as the electrolyte under high pressure rushes out of the nozzles with great speed, it carries with it a portion of the surrounding electrolyte at low pressure, then the speed of the whole stream is slowed d own in the diverging portion ofthe nozzles in which a portion of the momentum of the current is gradually converted into pressure-- Then the electrolyte Iforced through the nozzle or nozzles is evenly distributed on one side of the group of electrodes so as to produce between these a circulation as uniform as possible.

In order that the invention may be more fully understood, I shall describe by way of example an apparatus suitable for' use in electrolysing copper sulphate solutions, witha channel such as disclosed in my prior Patent No. 1,466,994. In the drawings:

Fig. 1 is a cross-sectional view lon line I-I (Fig. 2) of a l,channel containing a plurality of groups of electrodes arranged parallel to the axis of said channel.

Fig. 2 is a longitudinal section on Fig. 3, and

Fig. '3 is a plan line II-II of View partly in section on line III--IlI of Fig. 1.

Fig. 4 is a cross-sectional view on line`IV-,IV of Fig. 6, showing a further embodiment of my invention.

Fig. 5 is a sectional elevation on line V-V of Fig. 6, and

Fig. 6 is a corresponding plan view partly in section on line VI-VI of Fig. 4.

Fig. 7 is a cross-sectional view on line VII-VII of Fig. 9, il'ustrating still another embodiment of my invention.

Fig. 8 is a sectional elevation on line VIII- VIII of Fig. 9, and

Fig. 9 is a corresponding plan view partly in section on line IX-IX of Fig.'7.

Referring to Figs. 1 to 3, I is the trough-shaped vat or channel which is made of concrete and covered inwardly with a coating of material Iboth insulating and acid-resisting, for example an asphalt coating. In the channel are arranged successive groups of electrodes separated from 'each other by free spaces iilled with electrolyte.

At the place of each group of electrodes, the channel is divided into narrow passages by longitudinal partitions 2 between which are inserted the cathodes 3 consisting of thick plates of con ducting material. The partitions 2 and the inner walls of the channel opposite the cathodes are covered with lead sheets 4 which form the anodes. Starting sheets 5 intended to receive the metal to be deposited are provided around the cathodes 3 on which they are laid and secured in position by means of one or two sets of fastenings 6 according as one or two sheets are used on each cathode. l

The several groups of electrodes are mounted in series, the electrodes of the same polarity in each group being connected in parallel. 'I'he current is supplied from a bus bar I which runs along one of the edges of the channel and is divided at suitable points 8 into as many sections as there are groups of electrodes. Each section of the bar I is connected on the one hand to a cross-conductor 9 to which the anodes of one group 4 are secured by lugs I0 and on the other hand to a cross-conductor II secured to a removable cover I3 which supports the cathodes of the next group by means of lugs I2 and keys I4. The clamping of keys I4 against the con` ductor II also provides the necessary electric connection between the cathodes 3 and bar 1.

The longitudinal partitions 2 which may be of concrete, have an enlarged front portion I5. They rest on a bottom plate I6 to which they are secured Iby lugs I'I. The plate I 6 made of concrete with an asphalt coating rests on rigid supports I8 of glass or porcelain and separates the electrodes from a lower canal I9.

The cover I3 is protected on its underside by an acid-resisting material, and it is shaped as a horizontal plate with raised longitudinaledges 20. As shown in Fig. 1, the vat or channel I is wider at its top portion 2I,the reason therefore being that the electrolyte level in the channel shown at 22 is such that the cathodes are completely immersed in `the sglution. The lower edges 23 of the cover I3 engage Without pressure in grooves 24 provided in porcelain blocks 25 on the side walls of the channel I. With this arrangement, if a leakage takes place under the edges 23 owing to the high pressure under the cover I3 the leaking solution finds a convenient outlet in the wider portion of the channel.

The longitudinal chambers between partitions 2 which comprise each a double-face cathode 3 terminate at their upstream end in convergingdiverging conduits 26 formed between the enlarged portions I5 of the partitions 2. The electrolyte is injected into said conduits by nozzles 21 branched on pipes 28 connected with the delivery opening of a pump 29 through pipes 30 and 3|. The pump 29 comprising a helical wheel is driven by bevel gears 32 and 33 from a motor 34. These pipes and the pump are made of hardened lead in order to resist sulphuric acid.

A current of electrolyte ows through the whole length of the channel and returns in opposite direction through the lower canal I9, the individual groups of electrodes being each subjected to an accelerated current of electrolyte from the injectors.

The electric current supplied to the bus bars 1 and 9 is distributed to the various lead anodes. From the cathodes the current iiows through conductor II to the bus bar section 'I which is connected with the next group of electrodes and so on.

The operation of the apparatus is as follows: The starting sheets 5 being applied against the cathodes 3 and secured to each other at 6, the cover I3 is lifted by means of the rings 35. The cathodes are lowered into place, and then the cover is placed with its edges on the sides of the channel. Clamps 36 are provided in order to prevent the cover lifting. 'I'he motor 34 then is set in motion in order to start the forced circulation through the group of electrodes. A circulation of liquid is started along the arrows F1 and the electric circuit is closed by withdrawing the key 31 that kept the group of electrodes out of circuit.

In order to withdraw the cathodes with their deposits, the reverse operations are effected. When the pump 29 stops, the circulation in the channel is not stopped, as the horizontal partition I6 is interrupted at intervals so as to permit of the current being momentarily directed along the arrows F2.

It will be understood that the above described apparatus which is adapted to give high speed circulation between closely spaced electrodes, may be modified within the scope of my invention. 'I'hus the helical pump may be replaced by a centrifugal pump or by any other apparatus adapted to force the electrolyte under high pressure through suitable injectors. When several apparatus have to be supplied with electrolyte under pressure, it is also possible to feed the electrolyte from an elevated receptacle into which a portion of the electrolyte from the channel is forced by a single pump.

The arrangement of several apparatus in a single channel makes it possible to adjust the levels and in a general manner the improved system of circulation makes it possible to carry out a large number of electrolysis operations under higher current densities than heretofore. It permits of increasing the output of the apparatus without increasing their size, or it enables with the same output, much weaker solutions to be electrolysed. This process of course is not limited to the use of a channel-vat, and it may be used in all cases where it is desired to promote the circulation of electrolyte.

Instead of using a plurality of injectors for each group of electrodes, I may use a single injector adapted to force the liquid into a chamber from which it is distributed between the respective pairs of electrodes. Such an arrangement is illustrated in Figs. 4 to 6, in which there is provided in front of each group of electrodes 3, 4, a cross-partition 40 having a wide opening connected with a converging-diverging tube or conduit 4I. Into this conduit ows a current of electrolyte from the pressure pipe 42 of a pump 29, which current induces the surrounding electrolyte to be sucked into the conduit. From the conduit 4I the liquid under pressure reaches the distribution chamber 43 whence it flows between the electrodes in thin parallel streams. It is then sucked'partly into the conduit 4I of the following group of electrodes as shown by arrow F1 (Fig. 6) and partly through the return canal. 44 and the suction opening 38 of pump 29 as shown by arrows F2.

In the example illustrated in Figs. 4 to 6, the connections of the electrodes are similar to those shown in Figs. 1 to 3. A cover I3 closes at the top the chamber 43 and the narrow passages between the electrodes.

In Figs. 7 to 9 I have shown cathodes 3 which are merely suspended from conductors 45 resting on cross-bars 46 which in turn are connected with the longitudinal bus bar 'I running along the channel I. Y

A return canal I9 is provided under the groups of electrodes. The arrows F. F1, F2 and Fa show the respective paths of the main currents of electrolyte in operation. F represents the current directly injected by the pump, F1 shows the path of the portion of electrolyte carried by the suction of the injector towards the next group of electrodes, F2 the path of the portion of electrolyte sucked by the pumpand F3 the path of the currentthrough the return canal I9 from the downstream to the upstream end of channel l.

It will be understood that further changes may be made without departing from the scope of the appended claims.

I claim:

1. In an apparatus for the electrodeposition of metals, the combination of a channel, a plurality of groups of closely spaced parallel electrodes arranged in succession in said channel, a conduit having a constricted portion and a iiaring outlet opening into a confined space on the up-stream side of each of said groups of electrodes, pumps adapted each to discharge electrolyte under pressure into the constricted portions of said conduits, said pumps being adapted to suck a limited quantity of electr/elyte from said channel, said conduits having each a flaring inlet to allow the general body of electrolyte to be drawn therethrough together with the electrolyte discharged by said pumps and a return canal connected to said channel at both ends thereof.`

2. In an apparatus for the electrodeposition of metals, the combination of a channel, a plurality of groups of closely spaced parallel electrodes arranged in succession in said channel, conduits opening into laterally-confined spaces on the up-stream side of each of said groups oi electrodes, said conduits having each `a constricted middle portion and outwardly iiaring ends, pumps adapted each. to suck a limited quantity of electrolyte from said channel and discharge it into each of said conduits, said conduits being open at both aring ends to allow the general body of electrolyte to be drawn therethrough and between said electrodes together with the electrolyte discharged by said pumps, and a return canal communicating with said channel at both ends thereof and at points between successive groups of electrodes.

3. In an apparatus for the electrodeposition of metals, the combination of a; channel, a plu-' rality of groups of closely spaced parallel electrodes arranged in succession in said channel, conduits on the 11p-stream side of each group of electrodes for feeding electrolyte thereto, said conduits being open at both ends, a pump for injecting a limited quantity of electrolyte between Y the electrodes of each of said electrode groups,

` Pump,

a suction pipe connected to said channel for each a pressure pipe for each pump, delivery nozzles connected to said pressure pipe, said nozzles opening into said conduits, the arrangement being such as to cause the general body of electrolyte to be drawn through said conduits and between the electrodes of each group, and a canal connected to said channel at both ends thereof, said canal forming a return path independent of said pumpsfor the general body of electrolyte.

4. In an apparatus according to claim 3, the suction pipe of each pump being connected to said channel on the down-stream side of a group of electrodes, and the pressure pipe of said pump opening into a conduit on the up-stream side of said group.

5.' In an apparatus according to claim 3, alternate electrodes having enlarged ends, said conduits being formed between adjacent enlarged ends of said alternate electrodes.

6. An apparatus according to claim l, the return canal being arranged under and adjacent said channel, a partition separating said canal from said channel.

'7. An apparatus according to claim 1, said channel being wider at the top, a cover above each group of electrodes, said cover having raised longitudinal edges engaging in the wider portion of said channel, and means on said cover and on said channel for forming a liquid seal along both sides of said channel.

8. In an apparatus for the electrodeposition of metals, the combination of a channel, a plurality of groups of closely spaced parallel electrodes arranged in succession in said channel, a partition extending across said channel in front'of each of said electrode groups, a conduit extending through said partition,` said conduit having a constricted middle portion and outward flaring ends, a pump for feeding a limited quantity of electrolyte under pressure to each of said electrode groups, each of said pumps having a suction port connected with said channel and a pressure pipe opening into one of said conduits, and a return canal connected with said channel at both ends thereof.

9. In an apparatus according to claim 8, said pumps being arranged on one side of said channel, each pump having its suction port adjacent the down-stream side of one group of electrodes v and its pressure pipe opening into the conduit for feeding the next group of electrodes.

10. In an apparatus according to claim 8, said return canal extending along one side of said channel and being connected therewith at points betweenv successive groups of electrodes.

11. In an apparatus for the electrodeposition of metals, the combination of a channel, a group of closely spaced electrodes arranged longitudinally in said channel, means for building up an increased pressure in the electrolyte in front of said group of electrodes, said means comprising a conduit parallel to the electrodes, said conduit having open flaring ends and a constricted portion therebetween, a pump for sucking electrolyte from the rear of said group of electrodes and delivering said electrolyte into the constricted portion of said conduit, and walls for separating the electrolyte under -increased pressure from the upstream portion of said channel.

ALFRED CREMER.

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