US2597296A - Forming starting sheets for electrolytic refining of nickel - Google Patents

Description

y 1952 w. J. cook ET AL E 2,597,296

FORMING STARTING SHEETS FOR ELECTROLYTIC REFINING OF NICKEL Original Filed Oct. 1, 1948 2 SHEETS--SI-1EET l J: -xrl: I

i I N V EN TOR 5 1/41/7250 Jen/5s 6 0% GXAL y 1952 w. J. cooK ET AL 7 2,597,296

FORMING STARTING TS FOR ELECTROLYTIC REFI NG 0F NI Original Filed 001:. l, 194 BEETS-- ET 2 INVENTO Patented May 20, 1952 FORMING STARTING SHEETS FOR ELEC- TROLYTIC REFININ G OF NICKEL Wilfred James Cook and Joseph Howard Tuck, Port Colborne, Ontario, Canada, assignors to The International Nickel Company, Inc., New York, N. Y., a corporation of Delaware Original application October 1, 1948, Serial No.

Divided and this application June 10,

1950, Serial No. 167,342. In Canada June 12,

4 Claims. (Cl. 204-412) The present invention relates to the art of producing electrolytic nickel, and, more particularly, to the production of starting sheets used as oathodes in the conventional process of nickel electrorefining.

In conventional practice, starting sheets have been produced by the plating of a thin sheet of substantially pure nickel on a mother plate of stainless steel or other suitably inert metal, such as a nickel-chromium alloy, stripping the starting sheet therefrom, and then manually straightening the stripped starting sheet prior to its use as the cathode in the electrolytic refining process. As thus produced, the starting sheets are in the form of plain blanks or flat sheets which, by reason of their size, relative thinness, and lack of rigidity result in troublesome and expensive operational difiiculties. The inherent tendency of the cathode sheets is to warp or curl after a relatively short period in the refining bath making it necessary to remove the sheets from the bath and to restraighten them before continuing the growth of the cathodes. Such warping of the cathode sheets if allowed to progress would result in short circuiting between the cathodes and anodes causing current losses, diaphragm failures, and interruption to the process.

The initial straightening of the starting sheets as manually performed is objectionable under industrial conditions because careless operators either do not properly straighten the sheets or, as commonly experienced, dirty the face of the sheets leading to undesirable surface effects on the face of the finished cathode known as honeycombing and/or berrying. The manual straightening is moreover costly and labor-consuming. The further requirement of restraightening encounters still greater objections and difficulties incident to the nature of the operation. This necessitates removal of the cathode sheets from the bath with the coincidental dispersion of electrolyte causing occupational hazards and interference to good electrical contacts.

While efforts have heretofore been made to remedy the objections and difficulties, they have shown no substantial degree of success in the electrolytic refining of nickel largely by reason of the peculiar properties of this specific metal. For example, the high modulus of elasticity of the metal renders it extremely difficult to straighten mechanically. In addition, the inherent tendency to form berries at local high spots frequently leads to catho de-anode short circuits with the resulting loss of current. a The attempted solutions of the problem presented have included varied formation of the starting sheets to obtain stiffening effect including corrugating of the sheets which, however, have heretofore proven ineffective and unsatisfactory for the purpose in its application to practical nickel refining. In this connection, it has been found that in the corrugating of the sheets over extended areas of parallel corrugation warping of the sheets occurs particularly during electrolytic separation with resulting short circuiting, particularly due to the local area warping or deflection of the metal.

In accordance with the present invention, the objections and disadvantages incident to the warping of the starting sheets have to a large degree been eliminated'by the provision of novel starting sheets with special structural arrangements to provide stifiening deformations of the metal in a special pattern, designed to reinforce or stiffen the metal against bending or warping in all directions, and of a character permissible of successful use in practical electrolytic nickel refining. Important features which materially contribute to the successful use in the specific process comprise an improved starting sheet having stiffening deformations wherein the major surface areas of the starting sheets are plane or flat surfaces and wherein the deformations of the metal provide elongated channels or ribs of shallow cross-sectional form and in an arrangement of the ribs providing maximum stiffening effect 7. with a minimum deformation of the metal or sheets.

It is an object of the invention in the production of electrolytic nickel to provide an improved method of manufacturing starting sheets used as cathodes in such manner as to produce a stiffened sheet of a character to maintain a straight sheet during the electrolytic separation and to provide the channel-rib formation by reversely offsetting the sheet material to balance or neutralize the warping tendencies incident to nickel deposition in the process of electrorefining.

A further object of the invention is in the production of electrolytic nickel to provide an improved method of manufacturing an improved starting sheet inherently stiffened in it structural formation, wherein the major portion of its surface area will constitute a plane or flattened surface, wherein the stiffening ribs are made by offsetting the metal and wherein the rib formations are of relatively shallow cross-sectional contour suitable to economic commercial production of the novel nickel starting sheets.

Another important object of the invention, involving the elimination of the detrimental features of the prior art, as encountered in the electrolytic production of nickel, is to provide a novel method of manufacturing a starting sheet of per fected structure which shall be inherently stiffened against warping in a manner to preserve its original flat plane during the entire period of electrodeposition in the practical nickel refining operation.

It is within the contemplation of the invention to effect important savings in operational costs in electrolytic refining of nickel which are likewise accompanied by advantages, such as the maintenance of clean contacts, resulting in uniformity of voltage with high ampere efficiency.

The invention likewise contemplates an 1111-.

proved method of producing the starting sheets of the character described wherein the initially stripped sheets are first roller straightened and subsequently die-pressed to form, thereby insuring uniform production of inherently stiffened starting sheets which will maintain their straight condition throughout the practical refiningprocess.

A further object of the present invention is to provide an improved method of forming starting sheets for electrolytic refining of nickel which compriseselectrodepositing nickel on a stainless steel blank, stripping the deposited nickel sheet therefrom, roll straightening the stripped sheet in repeated'passes with a turning of the sheet intermediate of each pass and finally trimming and. die-pressing the sheet to form a stiffened sheet having a major area of plane surface.

Moreover, the invention provides a process for the production of an inherently rigid starting sheet involvingassociated steps in an electrolytic nickel refining operation.

The invention further contemplates an improved process for electrolytic refining of nickel which comprises preparing a. cathode starting sheet by electroplating a stainless steel blank with substantially, pure nickel, stripping the nickel sheet from the blank, roll straightening the sheet, die-pressing the straightened sheet to provide the sheetwith spaced stiffening deformations occupying a. minor portion only of its surface area, and employing thesheets so formed as cathodes in the refining process."

Other desirable'features and advantages of the present invention will be more fully understood by reference to the accompanying which:

Figure 1 illustrates a plan View of a rectangular starting sheet embodying the features of the present invention;

Fig. 2 is a vertical and longitudinal sectional view thereof'taken on line 2-2 of Fig. 1;

Fig. 3 is a transverse sectional view thereof taken on line33 of Fig. 1;

Fig. 4 depicts a. sectional view illustrating a portion of the die structure employed in the production of the startingsheets and illustrating in section a portion of the starting sheet corresponding to a section taken on line 44 of Fig. 1;

Fig. 5 is a similar sectional view of a portion of the mating dies employed in the offsetting of the metal of the starting sheets wherein the starting sheet portion illustrated in section is that portion as indicated by the sectional line 5-5 ofFig. 1;

Fig. 6 shows a corresponding view illustrating the production of the portion of the sheet correspondingto the sectional line 66 of Fig. 1, and

Fig. 7 is a similar view of a die formation of modified structure.

In the embodiment of the:invention-illustrated drawings in in the drawings, the several features are embodied in the production of a cathode starting sheet formed as a rectangular blank or sheet of nickel. The rectangular. blank or sheet of nickel in its initial stage is produced as a plane sheet by the electrodeposition of substantially pure nickel upon a blank of stainless steel and by stripping of the deposited sheet nickel from the blank. The sheets as thus produced may, if desired, be roller leveled o1- initially straightened and are then, in accordance with the invention, diepressed for localized deformation or offsetting of portions of the sheet nickel to provide stiffening or reinforcing ribs or channels in an arrangement such as to stiffen the starting sheet against bending in all directions. The arrangement is such that the number and dimensions of the deformations are such that the major surface area of the starting sheet is a plane or flat surface and the stiffening deformations are such that the sheet is of unchanged thickness throughout. The deformations as shown in the drawings .are in their cross-sectional contour of shallow depth and relatively large radius and curvature thereby to provide on one side of the sheet a shallow curve or curved channel and at the opposite side of the sheet an arching or rib formation of substantially corresponding radius. These ribchannel stiffening deformations by reason of their shallow depth are of a form adapted for their economic production by die-pressing of the relatively high modulus of elasticity metal. Moreover, by reason of the shallow depth of the deformations with relation to their width,,the stiffening effect is provided with avoidance of high spots or ribs of a nature tending to buildup or berry during electrodeposition in such manner as to interfere with the refining process.

In Fig. 1 of the drawing, there is illustrated a preferred spacing and arrangement of the stiffening deformations formed by die-press offsetting of the metal. This spacing and arrangement in a rectangular sheet I comprises diagonally stiffened means, such as deformations 2 and 3. Between said diagonal. deformations is a plurality of ribs or'deformations 4 and 5.-which are parallel to the longitudinal edges of thesheet. A plurality of transverse ribs or deformations 6 and 1 are arranged perpendicular thereto and parallel to the shorter edges of the sheet. The said ribs and deformations are formed'by offsetting them to one side of the sheet. Associated with the longitudinal ribs is a pairof similar.reinforcing rib-channels or deformations 8-which are offset to the opposite'side of the sheetand which are arranged within an intermediate area thereof and parallel to an associated longitudinal edge. Similarly, reinforcing rib-channelsror deformations 9 are arranged within an intermediate area of the sheet and parallelto the transverse or shorter edge thereof. These reinforcing rib-channels or deformations are designed. to neutralize warping tendencies-as may occur at certain periods of the building upof-the cathode during electrodeposition.

The starting sheets may have any, appropriate size, say about 29" x 39", with thecurved or arched deformations having a limited or-restricted depth and width of said about 1%" andabout 1 respectively. The .ratio of width to depth of the deformationhas been found tobe somewhat critical and is preferably of the orderof 16 to 1. Novel starting sheets embodying these deformations have, under comparative test with .the customarily employed plain or straight starting sheets, shown marked superiority in the resulting product without restraightening even though these conventional straight sheets were lifted and restraightened within twenty-four hours.

Th spacing arrangement of the deformations used by the invention provide-s for the major surface area of the sheets to be plain fiat surfaces and further provides a marginal fiat surface of sufiicient area to permit the attachment of the usual terminal straps employed for suspending the sheets in the tanks. The flat marginal portions are, accordingly, of a character to insure good electrical contact with the straps which are customarily secured by spot welds. The starting sheets may normally have a thickness of about 0.040 inch.

In Figs. 4 to 6, a suitable arrangement is illustrated for die-pressing the starting sheets to incorporate therein the stiffening deformations or ribs in accordance with the present invention. Upper and lower mating dies l0 and II are employed and provided with die inserts I2 and I3 having their active or formingsurfaces conforming to the configuration to be produced. In practice, it has been found beneficial, at times preliminary to the die-pressing of the deformations, to subject the stripped sheets to a roller-straightening operation after which the sheets are diepressed with a simultaneous trimming or shearing of the sheets to proper size. The roller straightening is found to be advantageous particularly with sheets having low ductility which in view of the springine-ss of the metal does not readily straighten under the press. The roll straightening is desirably performed with a single pass but may necessitate repeated passes with a turning of the sheet end for end or lengthwise rolling in reverse directions.

In Fig. 7, a modified die structure is shown wherein the upper die insert I2 is formed as a clearance die and wherein the offsetting is effected entirely by the lower cooperating die insert l3.

The preparation of the starting sheets of the unique structural form results in substantial operational and maintenance economies, particularly as related to the elimination of the requirement for restraightening of the sheets during the process and the detrimental conditions incident thereto.

It is to be observed that the present invention provides an improved method of forming starting sheets especially adapted for use with and in combination with the electrolytic refining of nickel, including the steps of electrodepositing nickel on a metal blank, stripping the nickel deposited sheet therefrom, roll straightening the stripped sheet, and finally die-pressing the sheet to form a stiffened starting sheet having a major area of plane surface to provide starting sheets which are inherently stiffened to a degree effective to preserve its original flat plane during the entire period of electrodeposition in the practical nickel refining operation. The requirement of restraightening of the cathode sheets during the refining operation is accordingly eliminated together with the objections as referred to incident to the restraightening operation such as caused by dispersion of the electrolyte.

While a preferred method of producing starting sheets suited for nickel refining is described and shown, it will be understood that variations and modifications thereof may be resorted to without departing from the scope of the invention as defined in the appended claims. For insigned particularly for meeting the more severe conditions imposed in nickel refining, it will be understood that certain features thereof may be advantageously employed in the electrolytic separation of other metals which may offer less in difiiculties such as to provide for the economic formation of stiffened starting sheets. Also, the roll-straightening operation, as hereinbefore described, may be modified by first straightening of the sheet through a roll pass and then repeating with a rotation of the sheet through a angle instead of the angle as hereinbefore referred to.

The present application is a division of our copending application Serial No. 52,302 filed under date of October 1, 1948, now Patent No. 2,578,968, issued December 18, 1951.

We claim:

1. The herein described method of forming starting sheets for electrolytic refining of nickel which comprises electrodepositing nickel on a stainless steel blank to form an electrodeposited sheet, stripping the said sheet of electrodeposited nickel from said blank, roll straightening the stripped nickel sheet in repeated passes with turning of the sheet intermediate of each pass, die-pressing said nickel sheet and offsetting multiple spaced deformations located at both sides of each central axis of the sheet and extending parallel to the edges of the sheet, said multiple deformations being spaced from said edges by plane surface marginal areas and having certain ones offset from one side of the sheet and others ofiset from the other side of the sheet and forming centered deformations extending diagonally of the sheet including deformations coextensive therewith, and controlling said deformations to have a depth of about one-sixteenth of an inch and a width of about one inch whereby a stifiened starting sheet is formed having a major area constituted of plane surfaces and a minor area constituted of offset portions in the form of shallow elongated deformations of arched crosssectional contour.

2. The herein described method of forming starting sheets for electrolytic refining of nickel which comprises electrodepositing nickel on a metal blank to form an electrodeposited sheet, stripping the said sheet of electrodeposited nickel from said blank, roll straightening the stripped nickel sheet, die-pressing the said nickel sheet and offsetting multiple spaced deformations located at both sides of each central axis of the sheet and extending parallel to the edges of the sheet, said multiple deformations being spaced from said edges by plane surface marginal areas and having certain ones ofiset from one side of the sheet and others offset from the other side of the sheet and forming centered deformations extending diagonally of the sheet, and controlling said deformations to have a width to depth ratio of 16 to 1 whereby a stiffened starting sheet is formed having a major area constituted of plane surfaces and a minor area constituted of offset portions in the form of shallow, elongated deformations of arched cross-sectional contour extending to one side of the sheet.

'3. The process of electrolytic refining nickel which comprises preparing cathode starting sheets by electrodepositing substantially pure nickel on a stainless steel blank, stripping the said sheet of electrodeposited nickel from said blank, roll straightening the stripped nickel sheet, diepressing the said nickel sheet and offsetting multiple, spaced 'der6rm ations -1ocated at ham sides of each central axis of thesh'eet and ex: tending parallel to' the edges-of the sheet, said multiple deformations being" spaced from said edges by plane surface niarginal -areasand havingc'ertain ones offset from one side'of the sheet and others offset from the otherside of the sheet and. forming center deformations extending diago nally of the sheet and including deformations coextensive therewith; andcontrolling said deformationsto have a width to depth-ratio of 16 to 1 whereby a stiffened starting sheet is formed having a major area constituted of plane surfaces and a minor area cohstitiited ofofiset portionsin theform of shallow elongated deformationsot arched cross-sectional-contour and-employin'g'the sheets so formed as cathodes in the-refining proc--- ess whereby warping of the cathodes is materially reduced.

4; Theprocessof electrolyticrefining of nickel being spaced from said edgesby plane surface marginal areas and havingcertain ones offset from one side of the sheet and others'offset from the other side of the sheet and with centered deformations extending diagonally of the sheet and including a continuous" deformation coextensive with the sheet, and controlling said deformations to have a width to depth ratio of 16 to 1 whereby a stifiened starting sheet is formed having a major area con'stitut'd'of plane's'urfaces and a minor-area constituted of offset portions'in the'form of shallow, elongated deformations of arched cross-sectional contour extending to one side of the sheet and-whereby warping of-the cathode ismaterially reduced when said stiffened starting sheet is employed as the cathode in the said nickel refiningprocessQ JAM S- COOK.

J OSEPH' HOWARD TUCK."

REFERENCES CITED The following references are of record in the" file of this patent:

UNITED STATES PATENTS Number Name Date 1 ,128,676 Garbe'r et al; Feb. 16,1915 1,836,368 Eppsteiner et a1; Dec. 15, 1931 2,001,385- Gron'ningsaeter May' 14,1935 2,325,660" Chamberlain -Aug} 3; 1943 2,421,582 Shepard et a1. Ji1n'e 3', 1947

Claims (1)

1. THE HEREIN DESCRIBED METHOD OF FORMING STARTING SHEETS FOR ELECTROLYTIC REFINING OF NICKEL WHICH COMPRISES ELECTRODEPOSITING NICKEL ON A STAINLESS STEEL BLANK TO FORM AN ELECTRODEPOSITED SHEET, STRIPPING THE SAID SHEET OF ELECTRODEPOSITED NICKEL FROM SAID BLANK, ROLL STRAIGHTENING THE STRIPPED NICKEL SHEET IN REPEATED PASSES WITH TURNING OF THE SHEET INTERMEDIATE OF EACH PASS, DIE-PRESSING SAID NICKEL SHEET AND OFFSETTING MULTIPLE SPACED DEFORMATIONS LOCATED AT BOTH SIDES OF EACH CENTRAL AXIS OF THE SHEET AND EXTENDING PARALLEL TO THE EDGES OF THE SHEET, SAID MULTIPLE DEFORMATIONS BEING SPACED FROM SAID EDGES BY PLANE SURFACE MARGINAL AREAS AND HAVING CERTAIN ONES OFFSET FROM ONE SIDE OF THE SHEET AND OTHERS OFFSET FROM THE OTHER SIDE OF THE SHEET AND FORMING CENTERED DEFORMATIONS EXTENDING DIAGONALLY OF THE SHEET INCLUDING DEFORMATIONS COEXTENSIVE THEREWITH, AND CONTROLLING SAID DEFORMATIONS TO HAVE A DEPTH OF ABOUT ONE-SIXTEENTH OF AN INCH AND A WIDTH OF ABOUT ONE INCH WHEREBY A STIFFENED STARTING SHEET IS FORMED HAVING A MAJOR AREA CONSTITUTED OF PLANE SURFACES AND A MINOR AREA CONSTITUTED OF OFFSET PORTIONS IN THE FORM OF SHALLOW ELONGATED DEFORMATIONS OF ARCHED CROSSSECTIONAL CONTOUR.

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