US2578968A - Starting sheet for electrolytic separation of nickel - Google Patents

Description

STARTING SHEET FOR ELECTROLYTIC SEPARATION OF NICKEL Filed Oct. 1, 1948 Dec. 18, 1951 w. J. COOK ETAL 2 SHEETSSHEET l HIWHHHHHWWWW mmmunmm Rx y mm w m a F mfaw N a.

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51 ET AL TARTING SHEET FOR EL T OLYTIC SEPARATION OF Filed 0 SHEET 2 operational difiiculties.

Patented Dec. 18, 1951 STARTING SHEET FOR ELECTROLYTIC SEPARATION 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 Application October 1, 1948, Serial No. 52,302 In Canada June 12, 1948 1 Claim;

The present invention relates to the art of producing electrolytic nickel, and, more particularly, to the production of starting sheets used as cathodes 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 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 thecathode 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 objectional 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 laborconsuming. The further requirement of restraightening encounters still greater objections and difiiculties incident to the nature of the operation. This necessitates removal of the oathode sheets from the bath with the coincidental quently leads to cathode-anode short circuits with the resulting loss of current. The attempted soof 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 stiffening deformations of the metal in a special pattern, designed to reinforce or stiffen the metal against bending 0r 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 comprises an improved starting sheet having stiffening deformations wherein the major surface areas of the starting sheets are plane or fiat 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 with a minimum deformation of the metal or sheets.

It is an object of the invention to provide stiffening of the starting sheets in such manner as to maintain a straight sheet during the electro lytic separation and to provide the channel-rib formation by reversely offsetting the sheet ma terial to balance or neutralize the Warping tendencies incident to nickel deposition in the process of electro-refining.

A further object of the invention is to produce an improved starting sheet inherently stiffened in its structural formation, wherein the major portion of its surface area will constitute a plane or flattened surfacawherein the stiffening ribs are made by offsetting the metal and wherein the rib formations are of relatively shallow crosssectional contour suitable to economic commercial production of the novel nickel start ng sheets.

Another important object of the invention. involvin-g the elimination of the detrimental features of the prior art, is to provide a starting sheet of perfected structure which shall be inherdeposited sheet nickel from the blank.

' which are likewise accompanied by advantages such as the maintenance of clean contacts, re"- sulting in uniformity of voltage with high ampere efficiency. 7 i

The invention likewise contemplates an improved method of producing the starting sheets of the character described wherein the initially stripped sheets are first roller-straightenedand subsequently die-pressed to form, thereby insur- 5 ing uniform production of inherently stiffened starting sheets which will maintain their straightened condition throughout the practical refining process. I

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

Other desirable features and advantages of the present invention will be more fully understood by reference to the accompanying drawings in which Fig. 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 line 3-3 of Fig. l

Fig. 4 depicts a sectional 'view illustrating a portion of the die structure employed in the production of the starting sheets and illustrating in section a portion of the starting sheet corresponding to a section taken on line ii-fi of'Fig. 1;

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

Fig. 6 shows a corresponding view illustrating the production of the portion of the sheet corresponding to the sectional line 6-6 of Fig. l, and

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

In the "embodiment of the invention-illustrated in the drawings, the several features 'are incorporated in a cathode starting sheet formedas-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 theelectrodeposition of substantially pure nickel upon .a blank of stainless steel and by 'stripping'of'the The sheets as thus produ'cedmay, if desired be roller ieveiea 'or initially straightened and are then, in accordance with the invention, die-pressed'for localized deformation or 'off'settingof portions of the sheet nickel to provide stiffenin'gor reinforcing ribs or channels in an arrangement such as to S tifie n the Starting sheetagamst bending in all directions. The arrangement is such that the number and dimensions of the deformations are such that the major surface areaof 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 int'heircrosssectional contour of shallow epth-ahdre auve- 1y 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 rib-channel 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 withrelation to their width the stiffening effect is provided with avoidance of high spots or ribs of anature tending to build up or berry during electrodeposition in such manner as to interfere with the refining process.

InFig. 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 saiddiagonal deformations is a plurality of ribs or deformations 4 and 5 which are parallel to the longitudinal edges of the sheet. A plurality of transverse ribs or deformations 6 and I are arranged perpendicular thereto and parallel to the shorter edges of the sheet. The said ribs and deformations are formedby offsetting them to one side of the sheet. 'Associated with the longitudinal ribs is a pa'ir of similarreinforcing rib-channels-or deformations '8 which are offset to the opposite side of the sheet and which arearranged within an intermediate area thereof and parallel to an associated longitudinal edge. Similarly, reinforcing rib-channels or "deformations '9 are arranged within an intermedi- "ate area of theshe'et and parallel to 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 up of the cathode during electrodeposition.

The starting sheets "may have any appropriate size, say about '29", x 39", with the curved or arched deformations having a limited or restricted depth'and width ;of say about 1 6 and about 1 respectively. '-Ihe ratio of width to depth of the deformation has been'found to be somewhat critical and is preferably of the order of 16 to -l. No-velstarting sheets embodying these deformations ---have under comparative test with the customarily employed plain or straight startihg sheets, shown-marked superiority in the resulting product without restraightening even though these -c'o'nventio'n'al straight sheets were lifted and re-straightened within twenty-four hours. 7

The spacing arrangement-of the deformations used by the invention provides-for the majorsurface area of the sheets to be plain'fla-t- 'surfaces and further providesa marginal fiat surface 'of sufficient area "to permit the "attachment *of the usual teririinal straps employed for suspending the sheets in the tanks- The flat marginal portions are, accordingly, of a character to insure 'goodelectli'ca1 contact with l the straps whichare customarily securedby spot "welds. The-starting slieetsmay normally have a *thicknessof about 0.040inch.

'In Figs. 4 to 6 'a suitable arrangement illustrated for die pressing the starting sheets to in- *cdrporate 1therein'the stiffening deformationsor ribs in accordance with the present invention.

Upper "and lower-mating'dies 4'0 and 'l I are -emipley'ed and-provided with die inserts 1'2 and 13 having theinactive or-forming surfaces 'conforming to the configuration to be produced. In practice it has been found beneficial, at times preliminary to the die-pressing of the defamations, to subject the stripped sheets to a roller straightening operation after which the sheets are die-pressed 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 springiness 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 is formed as a clearance die and wherein the offsetting is effected entirely by the lower cooperating die insert.

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 re-straightening of the sheets during the process and the detrimental conditions incident thereto.

While a preferred formation of the novel starting sheets and an improved method of production 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 claim. For instance, while the present improvements are designed 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 difficulties such as to provide for the economic formation of stiffened starting sheets. Also, the roll straighten- 6 ing' 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.

We claim:

As an article of manufacture, a rectangular nickel cathode starting sheet for electrolytic refining of nickel having its major area constituted of plane surfaces disposed in a common plane and having elongated stiffening deformations formed by shallow offsetting of the metal with :an arched cross-sectional contour, wherein the deformations have a ratio of width to depth of about sixteen to one, said deformations including multiple spaced deformations at each side of the central axis of the sheet and extending parallel to the side edges of the sheet and spaced from the edges thereof by plane surface marginal areas and centered deformations extending diagonally of the sheet and including a continuous deformation coextensive therewith, and certain of the deformations being offset to the opposite side of the sheet from other of the deformations.

WILFRED JAMES COOK. JOSEPH HOWARD TUCK.

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

UNITED STATES PATENTS Number Name Date 964,121 Rose July 12, 1910 1,128,676 Garber et al. Feb. 16, 1915 1,574,055 Pedersen Feb. 23, 1926 1,754,125 Smith Apr. 8, 1930 1,836,368 Eppensteiner et a1. Dec. 15, 1931 2,325,660 Chamberlain Aug. 3, 1943 2,421,582 Shepard et a1. June 3, 1947

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