US3331763A - Blank for production of cathode starting sheets - Google Patents

Description

D. R. MABEY July 1s, 1967 BLANK FOR PRODUCTION OF CATHODE' STARTING SHEETS Filed Deo. 5; 1962 l l l l l l IN VEN TOR.

R. VMABEY DOUGLAS United States Patent O 3,331,763 BLANK FOR PRODUCTION OF CATHODE STARTING SHEETS Douglas R. Malley, Salt Lake City, Utah, assignor to Kennecott Copper Corporation, New York, N.Y., a

corporation of New York Filed Dec. 3, 1962, Ser. No. 241,967 Claims. (Cl. 204-281) This invention relates to the electrolytic reiining of metals, especially copper, and constitutes an improvement on blanks presently employed for the electrolytic dep osition of cathode starting sheets.

In the production of metallic copper from its ores, slabs of the metal having a purity of about 991/2% are produced by pyrometallurgical processes `for use as anodes in a linal stage of purication by electrolysis. Copper ions from the anodes are deposited, free of impurities, on thin cathode starting sheets of pure copper, where they build up into thick slabs of pure copper.

The cathode starting sheets are usually manufactured in the reiinery by electrolytic deposition of copper on polished and oiled blanks of copper or stainless steel. The deposited copper sheets are stripped on the blanks when they attain a thickness of about l@ of an inch. Stripping is made possible because of -the polished and oiled surfaces on which the copper is deposited. Nevertheless, stripping from conventional blanks is difficult, because the copper deposits along the edges of the blank as well as on the two mutually opposite broad faces thereof. The narrow edge strips along opposite lateral edges of the blank must be peeled down and then the broad sheets must be loosened and strippeddown simultaneously at both broad faces of the blank so as not to damage the lower margin of one or the other of the resulting two starting sheets because of the bottom edge strip still joining the two sheets. The resulting sheets must be trimmed and straightened.

Stripping of a formed starting sheet from a cathode blank is ordinarily performed manually lby use of a long handled, steel blade which is inserted between one of the formed sheets and the 'blank .and is then drawn outwardly to slit the upper part of each narrow edge strip free of the adjoining formed sheet, whereupon the slitting is continued ldownwardly and the narrow edge strips peeled olf as waste. The blade tends to score the blank and thereby promote adhension of subsequently formed sheets. Also, the blank tends -to become pitted by electrolytic corrosion along its upper margin immediately above the level of the electrolyte in ythe electrolytic tank and to promote adhesion thereat. Moreover, because of the nature of the handling required by this customary type of cathode blank, it is virtually impossible to apply automation to this phase of a refinerys operation.

Principal objectives in the making of the present invention were to so construct a cathode blank as to facilitate the stripping of formed starting sheets therefrom; to virtually eliminate starting sheet adhesion to the blank; to minimize, if not entirely eliminate, the formation of scrap or waste portions; to produce starting sheets of u niform and regular thickness and coniiguration, requiring only a minimum of trimming and straightening, if any; to enable automation techniques to be easily developed for and applied to the stripping of cathode starting sheets from cathode blanks; and to insure long and satisfactory service for the blank.

In accordance with the invention, the cathode blank comprises a substantially rigid and coherent 'body of dielectric material, preferably a suitable plastic, adherently laminated for the most part between two at and smooth face s heets of copper, stainless steel, or other suitable and electrically conductive material, and otherwise pro- 3,331,763 Patented July 18, 1967 viding a complete and continuous peripheral edging for such sheets in common, and margins therefor which are flush therewith. ln this way, not only are the lateral and bottom edges land edge margins of the blank effectively protected against the deposition of copper during the electrolytic formation of cathode starting sheets on the broad faces of the blank, but the important upper edge margins of the blank are also protected from electrolytic corrosion, pitting, and other deleterious eiects conducive to starting sheet adhesion. Each of the electrically conductive face sheets is completely surrounded by a peripheral margin of insulating material. Adherence of such face sheets to the dielectric body is essentially complete throughout, so that the resulting laminate blank is unitary and impervious.

Upward extensions of the electrically conductive face sheets, formed either integrally therewith or as separate sheet members closely joined thereto, are laminated Ihetween the upper marginal portions of the dielectric body at and extending upwardly from the face sheets, to provide electrical leads which are connected at their upper ends to bus bars.

It is presently preferred that these upward extensions of the face sheets be upwardly extending portions of the individual sheets themselves, brough-t in-to face-to-face juxtaposition between the upper marginal portions of the dielectric body and silver-soldered or otherwise suitably bonded or joined in good electrically conductive, faceto-face relationship. It is important in this connection that the inward bends of such upwardly extending portions, where they leave the outwardly-placed face sheets, be as abrupt as possible, so that the lower marginal areas of the respective upper marginal portions of the dielectric body can have protective thickness and still be Hush with the face sheets. Feather edges for such insulating arcas are undesirable, for there would be a tendency toward separation along such edges over a period of time, resulting in deposition of metal beneath such edges and adhesions of the formed starting sheets to the cathode blank. Moreover, there would be a tendency toward uneven deposition of metal along the dening edges of the face sheets, resulting in irregularity of configuration for the electrolytically-formed starting sheets.

The same consideration applies to the lateral and lower boundaries of the face sheets, making it highly desirable that the joinders between face sheet edges and the insulatin'g margins provided by the dielectric body be normal to the exposed, working faces of such sheets, or nearly so.

The closest approach that l have found to the concepts involved in this invention is disclosed in U.S. Patent No. 1,468,838, issued Sept. 25, 1923, to Charles H. Shuh, entitled Cathode for the Electrolytic Refining of Metals, where two separate cathode plates or blanks are carried in pockets formed at respectively opposite faces of a supporting frame of dielectric material. In order to retain these plates in the pockets and still have their exposed faces ush with the insulating bottom and lateral side margins of the frame, confronting margins of plates and pockets are beveled. This means that the exposed faces of the -cathode plates are underably bordered along their bottoms and lateral sides by feather edges of the dielectric frame. Additionally, a separate extension of the supporting frame Iprovides more feather edges along the top and leaves electrical lead extensions of such plates completely exposed to the electrolyte.

There are shown in the accompanying drawing specic embodiments of the invention representing what are presently regarded as the best modes of carrying out the generic concepts in actual practice. From the detailed description of thesepresently preferred forms of the invention, other more specific objects and features will become apparent,

In the drawing: Y

FIG. 1 is a broadside elevation showing a preferred Vconstruction of'the cathode blank of the invention;

FG. 5, a similar section taken on the line 5 5 of FIG.V 1; and

FIG. 6, a sectionl corresponding to the upper portion of FIG. 4, but showing a somewhat different construction.

Referring to the drawing:

The starting sheet cathode blank of FIGS. 1-5 isrshown as being of the usual rectangular configuration. It comprises a rigid and coherent-sheet-like body of dielectric material laminated for the most part between two flat and smooth face sheets 11 and 12 of some suitable electrically conductive material, such as copper or stainless steel, and otherwise providing a complete and continuous, peripheral, insulating edging 13, 14, 15, and 16 for the two sheets in common, and sets of margins 13a, 14a, 15a, 16a and 13b, 14b, 15b, 16h for the respective sheets, flush with their exposed faces.

The material of thel dielectric bodyshould 4be inherently impervious to electrolyte or should be made soin some suitable manner, and the two sheets 11 and 12 are intimately bonded and are adherent thereto throughout, including their ed-ge faces, so that the resulting cat-bode blank isV completely impervious to electrolyte when suspended in an electrolytic cell.

Electrical leads in common for theseY face sheets 11V and 12 are provided by respective upward extensions thereof 11a and 12a, which are preferably intimately joined in close electrical relationship, as by silver solder, and yare laminated between the dielectric material of upper edging 16 as they extend therethrough, Their upper,

exposed portions are preferably cut away centrally to y provide an opening 17 for handling purposes, and their upper ends are fastened between bus bars 19 and 2t), as by means of rivets 21. v

In order to avoid undesirable feather edges for the dielectricV material of upper edging 16 where the upward extensions 11a and 12a of the face sheets bend inwardlypto form electrical leads, such bends should be as nearly at right angles as is practical, see the bends 22 and 23 in FIG. 4. Likewise, to avoid uneven deposition of .metal and likelihood of laniinae separation at the join- 'ders between face sheet edges and the insulating margins 13a, 13b, 14a, 14b, etc., such joinders are made normal to the exposed, working faces of such sheets, or as nearly so as practical, see the joinders 24 and 25 in FIGS.

4`and 5. To avoid concentration of stress forces at the lower corners of face sheets 11k fand. 12, which would have a tendency to destroy adhesion at such corners if they were sharp, these corners are preferably rounded, as at 26, FIG. l, and the confronting portions of t-he dielectric margins'are made correspondingly arcuate.

In `the embodiment of FIG. 6, la single sheet or plate of copperror other electrically conductive material providesan electrical lead 30 for the face sheets 31 and 32, such sheet or plate lead 30 extending below and between the lupper portions of the face sheets 31 `and 32 andV joined thereto in face-to-face, good electrical contacting relationship in some suitable manner, as by means of silver solder.

Inthis embodiment, a single bus bar 33 is conveniently joined to the upper end of the single sheet or plate lead 3G as by means of welding 34. Advantages of this embodiment over that previously described are the absence of` any need to bend the face plates `and to solder them together, the fact that the joinders between the insulating upper margins of the dielectric body `and the thereto, or injection or other molding techniques, utiliz-Y ing suitable molds with appropriate provisions for prepositioning of the face sheets, may be employed; Such plastic materials as polyvinylchloride, polyurethanes, polyamides, unsaturated polyesters, vinyl acetate, various of the epoxy resins, various phenolic resins, etc. are satisfactory to a greater or lessk degree depending upon particular fabrication techniques employed, `as are natural and synthetic rubbers, such |as butadiene-acrylonitrile and polychloroprene. Various fillers, extenders, accelerators,l

catalysts, and exterior coatings can be lutilized, depending upon whether fabrication is by cold or hot procedures and whether or not heat and pressure, for example by means of a laminating or vulcanizing press, are employed to achieve t-he close adherence of component laminae necessary to produce required impermeability to the electrolyte utilized in the electrolytic cell. All of this `will Ybe apparent to fabricators accustomed to working with the indicated materials and techniques.

Various epoxy resins, such as that put out under Vthe proprietary name Epon, bond particularly Well to electrolytic copperV and form an extremely strong dielectric body when -reinforced with woven or braided glass fibers, which are available in several forms for convenient use. When this is done 4on a hand-fabricating basis, smoothing of the cured glass-reinforced epoxy resin by sanding and coating of the sanded surfaces with a hard-setting liquid resin, such as an unsaturated polyester, to prevent wicking and thus render the reinforced material impervious, produce a Very satisfactory product. When done-by an injection molding technique, the sanding and coating steps will normally be unnecessary.

Because there are no edge joinders between face sheets vat opposite faces of the blank nor likelihood of adhesion of electrolytically deposited starting sheets to the face sheets of the blank along the top margins thereof,

or, infact, along any of the margins thereof, the cathode blanks of the invention are especially well adapted to a vacuum stripping operation or to some other,V

handling technique that can be carried out and programmed on an automatic basis.

Whereas there are here illustrated and described struc- Y Y K defining a substantially unbroken area, said sheets,

being intimately bondedk to opposite broad faces of the dielectric body, Vinwardly Iof bounding margins thereof and substantially ush with and also intimately bonded to said margins, so as to be bordered by said dielectric material to form a laminated body; and electrical leads intimately joined to the face sheets and extending internally of said dielectric` body, through and emerging from a marginal edge portion and between'said opposite broad faces thereof; said' dielectric material being set and bonded to'V the other components of the laminated body under heat and pressure, whereby the face sheets are bordered by said dielectric material, substantially ush therewith, and the entire laminated body is essentially -unitary and impervious to electrolyte.

2. The blank of claim 1, wherein the electrically conductive face sheets are completely bounded by the dielectric material, and the electrical leads are integral eX- tensions of the respective face sheets and are bent inwardly and brought together within the confines of t-he dielectric body, so as to be encased by `dielectric material within a margin of said dielectric body.

3. The blank of claim 2, wherein there are additionally provided a pair of bus bars extending transversely of the electrical leads exteriorly of the dielectric body -and receiving said leads therebetween; and wherein there are also additionally provided means clamping said bus bars tightly together about said leads, in good electrical conductive relationship therewith 4. 'I'he blank of claim '3, wherein the respective electrical leads are sheets of electrically conductive material disposed in face-to-face contacting relationship las they emerge from and extend beyondrthe dielectric body.

5. The blank of claim 1, wherein the electrical leads are provided by a separate sheet of electrically conductive material extending between and intimately joined to the face sheets and projecting through a margin of the dielectric body.

6. The blank of claim 5, wherein there is additionally provided a bus bar extending transversely of the electrical lead sheet exteriorly of the dielectric body, and wherein said lead sheet is secured to said bus bar by welding.

7. The blank of claim 1, wherein the joinders of edge faces of the respective face s-heet with contiguous lp0rtions of the dielectric body are substantially normal to the broad faces of said sheets.

8. The blank of claim 1, wherein the face sheets are of rectangular conguration with corners thereof rounded. 9. The blank of claim l, wherein the dielectric body is a glass-iiber-reinforced plastic material. 10. The blank of claim 9, wherein the plastic material 1s an epoxy resin.

References Cited UNITED STATES PATENTS 724,862 4/ 1903 Henry 204-281 930,902 8/ 1909 'Thorp 2,04-281 1,018,901 2/1912 Haultain 204-286 1,468,838 9/ 1923 Sc-huh 204-281 1,470,883 10/ 1923 Schuh 204-281 2,332,592.J 10/ 1943 Norris 204-11 3,038,826 6/l962 Medl 161-186 3,230,163 1/ 1966 Dreyfus 2.04-281 JOHN H. MACK, Primary Examiner. HOWARD S. WILLIAMS, Examiner.

R. MIHALEK, Assistant Examiner.

Claims (1)

1. IN THE ART OF ELECTROLYTICALLY REFINING COPPER, A BLANK FOR THE ELECTROLYTIC PRODUCTION OF CATHODE STARTING SHEETS, COMPRISING A SUBSTANTIALLY RIGID, SHEET-LIKE BODY OF POLYMERIC, RESINOUS, DIELECTRIC MATERIAL; FACE SHEETS CONSISTING OF AN ELECTRICALLY CONDUCTIVE METAL DEFINING A SUBSTANTIALLY UNBROKEN AREA, SAID SHEETS BEING INTIMATELY BONDED TO OPPOSITE BROAN FACES OF THE DIELECTRIC BODY, INWARDLY OF BOUNDING MARGINS THEREOF AND SUBSTANTIALLY FLUSH WITH AND ALSO INTIMATELY BONDED TO SAID MARGINS, SO AS TO BE BORDERED BY SAID DIELECTRIC MATERIAL TO FORM A LAMINATED BODY; AND ELECTRICAL LEADS INTIMATELY JOINED TO THE FACE SHEETS AND EXTENDING INTERNALLY OF SAID DIELECTRIC BODY, THROUGH AND EMERGING FROM A MARGINAL EDGE PROTION AND BETWEEN SAID OPPOSITE BROAD FACES THEREOF; SAID DIELECTRIC MATERIAL BEING SET AND BONDED TO THE OTHER COMPONENTS OF THE LAMINATED BODY UNDER HEAT AND PRESSURE, WHEREBY THE FACE SHEETS ARE BORDERED BY SAID DIELECTRIC MATERIAL, SUBSTANTIALLY FLUSH THEREWITH, AND THE ENTIRE LAMINATED BODY IS ESSENTIALLY UNITARY AND IMPERVIOUS TO ELECTROLYTE.

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