US665426A - Art of obtaining chlorates by electrolysis. - Google Patents

Description

"NIL 665,426.

W. T. GIBBS.

ART 0F OBTAINING GHLORATES BY ELCTRULYSIS.

(Applicaticu med sept. 9, 1895.)

(No Model.)

Patented 1an. 8, l90i.

2 Sheets-Sheet l.

No. 665,426. Pa'tenied lan. 8, IQOI. W. T. GIBBS.

ART 0F DBTAINING CHLORATES BY ELECTROLYSIS.

(Application led Sept. 9, 1895.) (No Model.) 2 Sheets-Sheet 2.

UNITED- STATES PATENT OFFICE.

WILLIAM T. GI'BBS, OF IEUCK'INGHAM, CANADA, ASSIGNOR, BY DIRECT AND MESNE ASSIGNMENTS, TO THE NATIONAL ELECTROLYTIC COMPANY, OF

N EW' YORK.

ART jOF OBTAINING CHLORTATES BY ELECTROLYSIS.

SPECIFICATION forming` part ofl Letters Patent No. 665,426, dated January 8", 1901.

Application tiled September 9, 1895.

lTo all whom it may concern,.-

Be it known that I, WILLIAM T. GIBBs, a British subject, residing' at Buckingham, county of Ottawa, Province of Quebec, Do-

minion of Canada, have invented certain new and useful Improvementsin the Art of Obtaining Ohlorates by Electrolysis, fully described and represented in the following specification and the accompanying drawings, forming a to part of the same.

My invention relates to the production of chlorates from the chlorids of alkaline and alkaline-earth metals, and has for its object increase in the efficiency and economy of such processes. In these processes this difficulty has been encountered and has proved very serious. Inasmuch as when a solution of mixed salts is submitted to electrolysis every salt present is to a greater or less extent de;

so composed, that salt, the production of which is the object of the process, will, as it accumulates in the liquid, be itself to a certain extent decomposed by the action of the current, and a portion of the current will thus a5 be wastefully consumed. It has been usual to continue the electrolysis until the saturation of the bath .became such that crystallization would occur in the cell itself or in another receptacle into which the liquid was 3o drawn oi and allowed to stand for that purpose. As the percentage of the salt in the bath increased the percentage of current wasted in attacking it also increased and the ecieucy of the process diminished. While,

3S. therefore, the efficiency at the beginning might be good, that at the end was very low and the average showed a very large percentage of loss.

I have discovered that by making the dow 4o of the liquid through the cell continuous it becomes practicable to remove the salt from the bath rapidly and continuously and while its percentage is still small, and thereby to greatly reduce the quantity of current lost in uselessly decomposing it. Thus whereas the degree of saturation usually heretofore employed ln the practice of such processeshas been upward ot' ten percent. that employed in my process may be less than three per cent.,

Serial No. 561,911. (No specimens.)

and as a consequence the eiciency of the elec- 5o trolysis is nearly doubled. Having removed 'the chlorate from the liquid, I replenish it with chlorid and return it in a continuous stream to the cell. I have also discovered that the chlorids of the alkaline and alkalineearth metals can be electrolytically treated between metal electrodos separated from each other only by the solution andthe necessary insulation-i. e., without the use of a separating-diaphragm--with economy and suc- 6o cess. It has been heretofore supposed that the hydrogen freed at the cathode would reduce or prevent the formation of the chlorates unless the electrodes were kept separate by a diaphragm or unless the hydrogen were consumed at the cathode-as, e. g., by an oxid of copper electrode. It has also been considered desirable to thus separate the liberated hydrogen and chlorin to prevent the formation of hydrochloric acid and conse- 7o quent diminution of the amount of chlorate produced. I have, however, discovered in the course of my experiments that these rev actions do not occur in a substantially injurious degree when the percentage of chlorate is kept down to a low percentage by a continuous fiow of the solution through the cell and that as a consequence I can employ metal electrodes in close proximity toeach other. This is a great advantage, since the use of a 8o diaphragm largely increases the resistance of the electrolytic cell, and consequently the expense of the production', while the use of a non-metallic electrode which will consume the hydrogen is attended with disadvantages which seriously interfere with the economy of the process. This discovery enables me to construct a cell having peculiar adaptations for my continuous process, I am enabled to place the electrodes in close and immediate 9o proximity, and thus to use a, current of large amperage and low voltage. The cell in which these electrodes are contained is necessarily of small cubical capacity, since the latter cannot be greater in proportion to the electrodesurface than will properly feed the electrodes by the action of diffusion, and therefore it is not adapted to the old discontinuous proces.

In the lirst place its capacity is so small that the filling of the cell,the application of the current, and the emptying and the refilling of the cell would entail inconvenience which would makesuch use almost, if not wholly, impracticable, while if the solution passes through the cell in a continuous flow its capacity is ample.

Another very important advantage secured by the small size of the cell and the large amperageor density of the current Iam enabled to use is that I can produce all the heat necessary to raise the temperature to the proper poin-t for the decomposition of hypochlorites by the action of the current itself. Heretofore it has been usual on account of the large capa-city of the cell employed in the man ufac'- ture of chlorates to supply this temperature by meansof heat from an external source. This is very dilcult to do practically because of the necessity of using apparatus for conveying the heat of the solution which will be resistant to the action of chlorin. In this connection, again, the continuous flow of the solution, through the cell.is of great consequence, for the reason that the large amount of current I am enabled to use in the small cell would, if the electrolysis were conducted in the usual discontinuous manner, heat the bath much higher than is permissible, while the continuous flow of the solution reduces and limits the development of heat to such a degree as is desirable for the process-namel y, within the limits of 90 to 200 Fahrenheit, the preferable temperature being from` 110 to 120 Fahrenheit, With this construction of cell and with a continuous flow I am enabled to use a current of two to four (preferably three) amperes per square inch of electrede-surface, which very greatly increases the capacityof the plant in proportion to its size over anything heretofore accomplished.

Another important advantage secured is that I am able to control and regulate the temperature of the solution in the cells by regulating the flow of the solution, which as it enters the cell is cold and causes an overflow of the hot solution. This is a much more convenient means of regulating the temperature than by regulating thesupplyof extern al heat on the one hand or than by regulating the density of the current used on the other hand, and this advantage is of greater value where a battery of cells such as is especially adapted to my'process is employed lthan where single c ells are used, for this reason, that where a single current is directed through a battery of cells if it were attempted to regulate the heat in the cells by changes in the density of current all the cells would be affected by each change, whereas the temperature of the 'solution in different cells may be dilTerent, owing todifferent conditions of locations of the cells in the battery or different internal conditions in the cell or in the supply and delivery pipes leading to and from each cell. The flow of the solution through each cell, however, can

stance, platinum.

be separately and conveniently controlled, so as to properly limit and adjust the temperature in each cell separately from and inde-v 'lpendently of the others.

As regards the feature of my invention which consists in reducing, limiting, or regulating the temperature of the cell by means of continuous flow of thesolution I intend to claim the same broadly, whether the source of heat be the" current itself "or wholly or partly external to the cell. I have also devised a peculiar construction of cell specially adapted for the production of thesechlorates and preferably used'in carrying out my process. l It is necessary in these cells to use as an anode a lmaterial which is substantially resistant to the action .of chlorin-as, for inf The cost of this metal or equivalent material, however, makes impracticable the use of heavy sheets as electrodes, and the high resistance of platinum also unfits it for.use alone as an anode. It is also extremely diliicult to use thia'sheets of platinum as electrodes, owing to their tendency to bend and warp, and consequently shortcircuit. It is also disadvantageous to use compound plates made up of a cheap metal, which would, if used alone, be subject t'o disruption in the presence of chlorin plated or covered with resistant material, as platinum, for the reason that it is dillicult to make such covering at the angles of the plate impervious to the action of chlorin, and such plates when used have been found to have less durability than is desirable. Furthermore, whatever the material of the electrodes the use of the usual connecting-rods causes much trouble and expense, since they are both inconvenient in themselves and continually liable to disintegration through accidental contact with the chemicals. I have overcome these diliiculties by using for one side of each cell a plate of cheap metal-as, for instance, lead faced with platirum or other` substance substantially resistant to the action of chlorin-causing the plate and facing to project beyond the other parts of the cell which inclose the solution, so that only the plain face of the plate will be exposed to the solution, and employing this platinum face as the anode of a single pair of electrodes contained in the cell, this being my preferred construction, it being understood that I do not limit myself to it. This facingof platinum or other resistant substance can be made very thin without disadvantage, since strength and rigidity are supplied to it by the metal backing, which cannot be reached by the solution. The dif- IOO iiculty of making connections is also avoided,

since these are made through the wall of the cell, and the cell or cells being preferably closed and arranged as described. chemical attack upon parts of the circuit other than the electrolyte is avoided. I have also devised a feature of. construction which practically overcomes another dilculty ordinarily encountered in such processes-viz., polarivertical wires or metallic rods electuallyl prevents polarization, The bu bbles of hydrogen` 'being spheres have the least-possible contact with tile cylindrical surface of the wires or rods. Consequently they do not adhere there- `rto, bu't'roll up the wires tothe top of the cell and there escape. In order to obtain theA best results, these rods should be of metal 4 and of small diameter, sincethere is no other material than metal whichis equally suitable for the purpose, and if the diameterof the rods be large the surface approximates to a plane surface and has -a tendency tohold the bubbles of hydrogen. I have found'tlle best results to be secured by a small rod or wire,

by which I mean a rod or wire having a diameter less than a quarter of an inch.

In order to facilitate the building up of a series or combination of4 cells which. shall have any desired capacity, I cause the metal 'plate which .serves as the backingfor the lmeans of-'an insulating-gasket entirely separ.construction has greatradvantagesuin con anode ofy one cell to serve as the rea-r wall of another cell placed in contact therewith, and

to simplify and protect the connect-ions I providein each cell au interior metallic connection between each cathodeand this rear wall of they cell, as by lining the interior of the cell between the two in whole or in .part with metal or making this part of the cell entirely of metal, providing mere conducting'c'onnections between the Vcathode'and the rear wall.

VIt will of course .be understood thatsuitable videdA with metallic connections, ,as above.

rating those parts ,of Ithe celiycon-nected with the two electrodes, respectively, and held in.

place by a proper'fastening or clamp.-placed upon the .cell or series of cells.. By. this constructionl secure a unit for use in constructing a series of cells, such unitc'ontaining an anode and a cathode belonging,respectively, to adjacent--pairs of eleetrodes,whichnni`ts when combined with 'interposed insulatinggaskets constitute fa seriesof cells in=which the path of the current lies entirely throughv the. electrolyte and -t-hey ce-llwalls, exterior connections being whollydispensed with, el;` cept at the tweextremites of the series. r This Vvenicnce'anddurability.

In 'tixed- -awings annexed, Figure lrepres sente a vertical cross-section 'of a seriesoff cells made in accordance with ,my invention :and set. upv4 for. use'. .-Eig. .2- is -a side elevation of one .ofthecells-iseenon line 22.01" liig.y 1,-

"the-point of-view;A beiuglto the leftfof Fig. 1';

cell preferably used in carrying out my proc ess. Each cell consists of a frame A, (shown in vertical cross-section in Eig. l and in side elevation in Fig. 2,) which may befof instal, but which I prefer to make of wood, with metallic or other conducting resistant lining B, as shown, or which may be of other material not subject to, attack by the solution. Upon one side ot' y this frame are attached the rods or wires C, constituting a. cathode, and on the other side ametallic plate D, faced with platinum E, constituting au anode. The cathode may be of copper, zinc, or other suitable metal, as likewise may be the liningr B and the plate D. I prefer copper for the cathode and lead for the lining and the plate. -It should be observed that itis not essential that the lining B be continuous over the entire surface of theframe A, it-being sufficient if. conducting connection is made between, the cathode and plate D, and the mal electrolytic process, and vents H are provided at the tops of the cells for the discharge there- "of and of the liberated gas. In .order that the cells may .be kept always llull, these vents are .placed just above the inside level'oi" the top ofv each cell, the frame being recessed foi-.that

les

purpose, and, this recessie continued inward,

asshown in' dotted ylines in Fig. 2, in order to permitaccessvof the'solution to the tenti When .erected for use the framesare 'placed side by side, with a gasket betweenn each two, as shown in Fig. l,- andare lpreferably clamped together by means of. two end plates J K-,con-

' nected by bolts L. The platesJ K are separated from the cells by insolatingmaterial. The left-hand cell of the series is closed by a 4simple plate m, faeed with. platinum. The

platinum face on the metal back handcel-lis omitted. Each -pairoi electrodes is separatedby the corresponding gasket. To-prevent short-cir of .the right- .ouiting by bending of the wires,.horizontal yinsulating-irods O are provided between the electrodes, these`rods.being. supported by .ourvedportions of the wires, or other suitable supporter other appropriate insulating means mn'ybeemployed. l

Referring nowzto' the diagram Fig.3,. P represents the electrolysis cells "overflowing into. 'coolingchamkers QQ', which maybe one', two, or more innumber. l 'Il1ese cooling- IIO ' paratns.

chambers are shown as provided with coolingcoils R. The use'of such coils is an advan-` tage, since it secures the precipitation of a greater proporticn'of the chlorate in solution; but their use is not essential to my-process. S is a pump for returning the depleted so1u tion to the replenishing-vat T,where it meets a fresh supply of chlorid and is fed by the siphon X or other connection again into the cell.

The flow of the solution through the cells is, as I have stated, continuous, and the rate of flow and quantity of electric current used are so proportioned that the solution as it leaves the cell shall-have a small percentage of chlorate. This percentage is preferably less than three .per cent., and I have found the results to be excellent when it was as low as one and one-half ,to one and three-quarters per cent.

The capacity of the cell advantageous for use in my process is from two to four cubicinches per squarev inch of electrode-surface. If a greater amount of liquid in proportion to the electrode-surface is present in the cell, it

is diicult to maintain the requisite degree of heat by the action of the current, and the application of external heat to thecell is difiicult and expensive, and, further, the pres ence of a larger amount of solution than that indicated interferes with the proper diffusive action in the cell. are preferable, I do not limit myself to them.'

By the term close proximity of the electrodes I intend to indicate the closest prox.

imit'y which it is practicable to obtainbetween insulated electrodes-as, for instance, one-sixteenth to one-eighth of an inch. I do not, however, limit myself to such close'proximity except in those claims in which' the electrodes are specified as being in close proximity.

It is an advantage that tue now ot the liquid should,be continuous through the crystallizing-chambers and the replenishing-vat back tothe cell, as well as through the cell` itself; but continuous flow is not essential to this part of the process, and I intend to claim lin this patent the feature of continuous flow through the cell whether or not such flowI is continuous through the remainder of the ap-l I do not, of course, limit myself toany special dimensions of apparatus; but I may menj tion that I have found a convenient size for the cells to be twenty-six by eighteen inches with a thickness of three inches, the electrodes being about one-eighth of an inch apart. v 4

The action ot the apparatus as above described is that adapted to the manufactu of.A potassium chlorate and other Vchlora which are less soluble in waterthan the corresponding chlorids. i sodium'chlorate and of such -other chlorates as are more soluble than the corresponding chloride the separation of the chlorates is ef- While these dimensions In the manufacture of` ,saam

f ected by causing the chlorid to crystallize in the cooling-vata and the subsequent evaporation of the chlorate solution,a continuous fiow of the electrolyte being maintained through the electrolytic cell or cells.

It will be understood that the present 1nvention is not limited to the use of apparatus of the speciiicform shown and described, but 'that while the use of such apparatus is pre-1 ferred the carrying out of the rocess claimed herein by any other suitable crm of apparatus is within my invention.

The vcell and series of cells shown and described herein form the subject-matter of another application filed October 8, I1900, Serial 1. The process of obtaining chlorates from the chloride of alkaline or alkaline-earth metals which consists in subjecting the chlorid ih solution while flowing continuously throughja 4cell to the action of an electric current betweeix` two electrodes insulated from each other, but

otherwise separated only bythe liquid, the. density of thecurrent used being such as to maintain the solution in the cell at a temperature suitable for decomposing hypcchlorites,

'substantially as set' forth.

y2. The process of obtaining chlorates from the chloride of alkaline or alkaline-earth metals which consists in subjecting the chlorid in solution while flowing continuously through a cell' to the action of an electric current between two electrodes in close proximity and insulated from each other, but otherwise separated only bythe liquid, the density 'of-the current used'being suchas to maintain the f solution in the-cell at a temperature suitable for decomposinghypochloritos, substantially as described. '3. The process of obtaining chlorates from the chloride of alkaline or alkaline-earth metals which consists in subjecting the chlorid in rio solution while flowing continuously through a cell to the action of au electric current between two electrodes insulated from each other, butotherwise separated only b'y the liquid, the density ofthe current used being such as to maintain the solution in the cell at atemperature high enough for the decomposition of 4 hypochlorites, and the fiow of solution being.

stautially asset forth.

such as'to prevent thetemperature from rising.

above 200 Fahrenheit or thereabout, sub- 'up' 4. The process of obtainingchloratesfrom the chlorids of alkaline or alkaline-earth met als whichconsists' in subjecting the chlorid in solution while owing continuously'through a cell to the vaction of an electric current between two' electrodes insulated from each other, but otherwise separated only bythe liquid, the density of the current used .being such as to maintain the solution at a tempera ture high enough for the decomposition of hypochlorltes, and col'ltrollng'he wmpl'iill of the solution in thecell by regulating thel flow of the solution, subtantiallyasy set forth.

45. The process of obtaining chlorates from the chlorids of alkaline or alkaline-earth metals which consists in subjecting the chlorid in. solution while liowiug continuously through each of a series of' cells to the action of an electric current passing through the cells in series, between twoelectrodes in each cell insulated from each other, but otherwise separated only by the liquid, the /den'sity of the. current used being such as to maintain the solution in all the cells at a temperature highl enough for the decomposition-of hypochlorites, and controlling the temperature of the solution in each separate cell by regulating the flow of the solution, substantially as se forth.

6. The process of obtaining cnlorates troni the chloride of alkaline or alkaline-earth metals which consists in subjecting the chlorid in solution-while flowing continuously through a cell to the action of an electric current, between two electrodes insulated from each other, but otherwise separated only by the liquid, the capacity of the cell being from two to four cubic inches per square inch of electrode-surface, and the current employed bev lng from two to four amperes per square inch of electrode-surface, the density of the cnrrent and the liow of the liquid being so adjneted that the solution is maintained at a temperature suitable for the decomposition' of hypochlorites, substantially as set forth.'

7. The process of obtaining chlorates from the chlorids of alkaline or alkaline-earth metals which consists in subjecting the chloridin solution 'in a cell to the action of an electric current. between two electrodes insulated 'from each other, but otherwise separated only 'by the liquid, imparting heat to the solution in the cell by suitable means, and reducing the temperature of thesolution by maintaining the continuous iiow thereof through the cell, whereby is maintained in the cell a,tem perature suitable. for the decomposition of hy'pochlorites, substantially as described.

8. The process of obtaining chlorates from the chloride of alkalineA or alkaline-earth metals which consists in subjecting the chlord in solution while iiowing continuously through a cell to the action ot' an electric current between two electrodes insulated from' each other, but otherwise separated only by the liquid, imparting to the cell by suitable means heat sulicient to raise the temperature of the solution to a degree high enough for the decomposition of hypochlorites, and regulating the temperature 'by regulating the flow of the olultion through the cell, substantially as set ort 1.

9. The process of obtaining chlorates from the chlorids of alkaline or alkaline-earth metals which consists in subjecting the chlorid in solution while owing continuously through each of a series of cells to the action of an electric current ,between two electrodes in each cell insulated from each other, but otherwise separated only by the liquid, imparting heat to the solution in each cell by suitable means suicieut to raise the temperature thereof toa degree suitable for the decomposition of hypochlorites, and regulating the temperature of the solution in each cell-by regulation of the owpof the solution through the cell, substantially as set forth.

Intestimony whereof I have hereunto set my hand in the presence of two subscribing witnesses.

WM. T. GIBBS.

Witnesses! p M. H. PHELPS, A. L. KENT.

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