US1159154A - Apparatus for the electrolytic manufacture of alloys of light metals with heavier metals and the continuous treatment of such alloys for obtaining final products. - Google Patents

Description

I I E. A. ASHCROFT. APPARATUS FOR THE ELECTROLYTIC MANUFACTURE OF ALLOYS OF LIGHT METALS WITH HEAVIER METALS AND THE CONTINUOUS TREATMENT OF SUCH ALLOYS v FOR OBTAINING FINAL PRODUCTS.

APPLICATION FILED-MAR. 12, l9l2.

I 1,159,154. Pd tented Nov. 2, 1915.

5 SHEETS-SHEET I.

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E. A ASHCROFT. APPARATUS FOR THE ELECTROL YTIC MANUFACTURE OF ALLOYS OF LIGHT METALS WITH HEAVI ER METALS'AND THE CONTINUOUS TREATMENT OF SUCH ALLOYS FOR oaTAmme rum PRODUCTS. APPLICATION FILED-MAR. 12. I9l2. 1,159,154. Patented N 0 v. 2,1910.

5 SHEETS-SHEET 2.

\NVENTOR WITNESSES E. A. ASHCROFT.-

APPARATUS FOR THE ELECTROLYTIC MANUFACTURE OF ALLOYS OF LIGHT METALS WITH Patented Nov. 2, 1915. 5 suing-shin 3.

INYENTOR HEAVIER METALS AND THE CONTINUOUS TREATMENT OF SUCH ALLOYS FOR OBTAINING FINAL PRODUCTS. APPLICATION FILED MAR. I2, I9|2.

, WITNESSES ATTOK N EYS r I E.A.LASHCROFI.

APPARATUS FOR THE ELECTROLYTIC MANUFACTURE OF ALLOYS OF LIGHT METALS'WITH HEAVIER METALS AND THE CONTINUOUS TREATMENT OF SUCH ALLOYS FOR OBTAINING FINAL- PRODUCTS. APPLICATION FILED MAR. I2. I912.

:Patented Nov. 2, 1915;

5 SHEETS-SHEET 4.

'YIIITLIESEESL I INVEYNTOK c ATTORNEYS I E. A ASHCROFT. APPARATUS FOR THE ELECTROLYTIC 'VIANUFACTURE 0F ALLOYS OF LIGHT METALS WITH HEAVIER METALS AND THE CONTINUOUS TREATMENT OF SUCH ALLOYS l FOR OBTAINING FINAL PRODUCTS. 1,159,154.

APPLICATION FILED MAR. 12. 1912.

' Patented Nov. 2, 1910.

5 SHEETS-SHEET 5.

I 'l/wewnfi' I EDGAR niwnuaasncaor'r, or onnon, amas.

mPrARATUs For, .THE nLnc'raoLY'rIc AivUFAcrUnE or ALLOYS or new m'E'rALs wun HEAV ER-METALS ND THE co'lvrmuous'mnarmnn'r or sucn: ALLOYS-TOE OBTAINING FINAL PRODUCTS;

-To all whomz't may concern: f':

Be it known that I, EDGAR ARTHUR ASH- CROFT, a subject of the King of-G'reat Britain 1 and Ireland, and residing at 99Bucki1'1gham 5 Palace road, in the county of London, England, and at Sande Gaard, Balesttand, Sogn, Norway, electrochemical engineer, have 1nvented new and useful Improvements in an v a apparatus forthe electrolytic manufacture; 100f alloys of'light metals with heavier metals andthe continuous treatment of such alloys for obtaining final products, of which I the following is aspecification.

a veryeflicient manner the manufacture of alloys of light metals (particularly alkali metals) with heavier metals, such," for instance, as sodium with lead by, the electrol' ysis of fused salts'of 'lightfmetal's and'lthe' 2 0 simultaneous production of anode products, in a very pure condition, and. also. the con- "tinuous treatment .of alloys such as those aforesaid for obtaining final product's.

' My invention relates more particularly to processes in which a'salt of an alkali metal 'after'explained conditions it is possible. to use such a mixture of salts in the first cell (or a mixture of such salts) iselectrolyzed in a firstlcell over a cathode of molten lead,

or alloy, the resulting alloy of the alkali Y sodium alloy containing practically no mepotassium, or but little metallicpo ftassium. i

' For brevity of 'description I will presume metal and lead being then passed,' or re-I 30. moved, fromthe firstcell to a second cell and returned again and-so on continuously. The.

most important products obtainable by this means are the amids, cyanamids, cyanids, and hydrates; of the alkali metals, or the alkali metals'themselves or their peroxids,

but other metals, .such as calcium,-lithi and their derived products, may also e similarly produced.

I My invention'relates, particularly to means 49 for obtaining only on metal, or metal oom pound, (for instance sodiumior a compound thereof) as-a final productwhilestill obtaining the advantages which are known to accrue from using certain other metal salts in admixture inpthe electrolyte of the first cell; namely a lower fusing point and higher current efficiency; also to the obtainment of ;the anode product (for example gaseous chlorin) in more cencentrated form, as well,

50 as to improvements in apparatus whereby certain well known-difliculties are avoided and the several steps of the process are rendered morepracticaI and are cheapenedi Specification'oi Letters latent.

fPatentedNov.2,191.3] Application filed March 12,1912. .serialmesaavs. it

fused sodium chlorid in admixture with cult and in fact commercially impracticable to 'electrolyzefl pure fused sodium chlorid f alone, because high Lcurrent eiiiciency and Stable electrolysis canno-t beobtained in the; first cell if sodium chlorid be present alone. It is also known that a mixture'of sodium and. potassium chlorids, 'in about molecular,

proportions, fuses at such a com aratively low vtemperature (6X0 centigrade that the current efliciency-ishigh and theelectrolysis is stable but hitherto, under such conditions,* A metallic potassium in considerable quantities hasa-lways been deposited with the-metallic sodium into'the alloy and tends to pa'ssinto i the finalproduct. The presence of the po- .have found thatsby observing the hereinand to obtain in the second cell metallic 1 tallic that a mixture 'ofsodium chlorid and of potassium chloridi's fused in the first cell and ,th'at metallic sodium is to be produced in the second cell, but myinvention is not limited to the use of sodium-chlorid'and potassium --'-chlorid, nor to the production of metallic all such fused mixtures incontact with fused alloys I have foundthat sodium. In using reversible reactions occur at the placeof contact. of the electrolyte with, the alloy'in the first cell, at the place of 'con'tactof'the' 4 alloy with the electrolyte, or'reac'ting body, in the second cell,--and also (when metals are produced) at the'place of contact of the produced alkali metal I with the electrolyte in; All these j reversible reacthe second cell. tions occur at each place to anexte'nt in accordance with the proportions of the several metallic elements in' the alloy and in the fused salts respectively,and in all cases are 7 .promoted by agitation.

"In the' ease of admixtures of and required temperature,

" promote the described reversible reactions:

.alloy or vice versa,

potassiumv salts by reason of the greater combining energy of the potassium' base, it is found that although considerable quantities ofpotassium are, in the first instance, carried into the alloy by reason of the excessive current density which must be employed 1n all such apparatus, in order to maintain the tus is suitably arranged and proportioned, the said reverse reactions tend thereafter rapidly to increase the proportion of metallic sodium and to reduce the proportion of metallic potassium in the final. product as herein explained. for obtaining the desired. result according to my invention are the maintenance of a suitable proportion of the salts of the twometals and the alloys of these metals in the respective parts of the apparatus, particularly at the aforesaid places of reversible reactions, and a somewhat rapid circulation of the alloy and of-the supernatant fused body in the second cell.

reactions referred. to are If, in proportion to the sodium present in each case, much potassium be present in the alloy and but little in the supernatant melt,

an interchange will take place whereby sodium is substituted for potassium in the and these changes will proceed until a balance, or equilibrium, has been reached according to Well known physical and chemical laws. By this means therefore-it is possible as aforesaid to reduce the final potassium content of the product to none at all or to very.small percentages;

moreover in the first cell the typical reaction NaCl+K=KCl+Na 4 @9 although reversible like the others and proceeding only until equilibriuinis attained is far more powerful in one. direction than in the reverse direction, so that if freshly melted and continually renewed sodium chlorid be employed to react on the triple alloy in a separate receptacle before removing the sodium, it is possible to extract all or practically: all of the potassium from the alby, substituting sodium therefor and simul' taneously to regenerate the potassium chlorid required for use in yet, when the appara- The conditions necessary serving in either direction accordthe second cell is the the sametime securing a cell where there is a the first cell. This will in some cases present considerable economical advantages. The procedure in that case is as follows: The sodium chlorid which is to form the raw material for the electrolysis is first melted (preferably in a vessel heated internally by the electric current, the contents being also preferably agitated, or caused to rotate, by the same agent) in contact with the alloy containing both sodium and potassium which has just been produced in the first cell. The fresh salt ex tracts the potassium from the alloy and then passes to the first cell (containing a useful admixture of potassium chlorid) preferably while still in a melted condition, while the alloy now" free or practically free from potassium, passes off to the second cell.

I have found by experiment that by obthe aforesaid conditions and operating as described, the first cell may contain for example a mixture of 40 per cent. of sodium chlorid and 60 per cent. of potassium chlorid, which mixture insures a minimum fusing. point (67 0 centigrade) "and a very efficient and stable electrolysis, and under the conditions aforesaid metallic sodium containing less than one per cent. of metallic potassium can be obtained from the second cell and other-derivatives can be obtained in a corresponding state of freedom from metallic potassium. In most cases however in practice this will not be required and it will be sufiicient by the hereinafter described meanswhereby the electrolyte in the first cell is maintained in continuous motion relatively to the underlying alloy to effect the desired object to a sufiicient degree of completeness while at rich and concentrated anion product. According to this, preferred 'mode of carrying out my invention the first cell is provided with means for passing an electric current (preferably the main current) once of more than once aroun the cell so as tocreate a magnetic field and triple procedure.

so cause a. constant whirling of the fused 7 salt and a simultaneous stirring or agitation of the alloy, so that the bulk of the gaseous anion is projected toward the center of the hollow anodethrough led ofi for utilization which the pure gas is as is refor any purpose where undiluted quired, While the aforesaid reversible reactions are promoted to a considerable extent The portion of the cell outside the anode may remain open and under a suiiicient current of air to carry ofi (preferablyfor separate utilization) the small proportion of the gaseous anion which is given ofif at the periphery of the anode. The anode is preferably made of a graphite cylinder and is built up of uniform segmental longitudinal pieces fitted together, the interior of cylinder being preferably large enough to v the allow in case of need' ofaccess to the cell when'the central loosej cover of the anode is removed. V

The electrical-contact with each segment of the cylinder can Joe effected by providing a nietallic cap for the whole and separately securing each segment with a bronze or copper bolt having an extended point dipping into a molten lead contact. A

special device which may ,be employed for preventing the attack of air on the exposed outer. surface of-the graphite cylinder con- I sists in a recess in the graphite cylinder extending from just below the electrolyte to" a; few centimeters above it and filledwith refractory material which is confined in place 'by a sleeve of enameled iron or the like.

Suitable pipe connections are provided for leading off the rich and also the less concentrated gases from the cell to separate desti nations. To maintain the balance of the two metals in the apparatus during the continuous process on these principles, an amount of potassium chlorid corresponding to that ing eliminated by thereversible reactions referred to, for I have foundthatjreversible' of the potassium which may be found in the final product of the second cell should be fed into the first cell together with the sodium chlorid. The amount required will be much less' than heretofore and may usually be less than 2% per cent. 5 Other metallic salts may be used-in admixture with the principal salts, the metal of the diluting salt be-.

reactions also occur, with salts of such metals. Such other salts'may for example be salts of barium,- strontium,- calcium, lithium and the like. Another feature of this invention isthe employment'of an intermediate receptacle for the reception and'storage of the fused alloy in its passage between the two cells and of weirs or overflows tothe two cells for maintaining a constant working level, also the-provision of very simple devices forefiecting the circulation of the alloy between the respective parts of the apparatus. In the preferred construction all these objects are secured and practical difliculties hitherto encountered in confining the alloy are completely overcome by the use of a single casting. preferably of steel as the under part of the apparatus, as hereinafter more fully described. I

I have found that in order to maintain in both the first cell and the second cell'the constant level'of alloy surface whichis es- .sential to the maintenance of uniform and "efiicient electrolysis, or other reactlons, 1n-

the cells, as .well as to insure an even flow of the alloy from the first cell to the second cell and the regular return of the depleted alloy; which are also essential to successful. working, the channels of communication between the cells may very advantageously side of the circulating pump.

be provided with an intermedate receptacle placed'preferably in the-path of the alloy leaving thefirst'cell, which receptacle will allow of-considerable changes of bulk in the total circulating alloy (which changes take place on any change inthe proportion of alkali metal which it 'contains) without affecting either the constant level in either of the cells, or the even flow from cell to cell.

The fused alloypreferably passes over a suitable Weir or fixed level overflow from the first cell into the said receptacle and passes, or is pumped, therefrom (by a rotatingworm or by an ordinary pump for example) into the second cell, there being a passage from the second cell provided also with a weir or the like (which is preferably inside the said cell) by which the depleted metal passes back to the first cell thus completing the cycle. It is desirable also to provide a comparatively thin refractory lining of heat insulating (basic) material inside the first cell so that the alloy in contact therewith at a high temperature shall not too rapidly lose its heat to the casting and to the surrounding alloy which will be maintained at a lower temperature by external heating. I

The construction which I prefer is illustrated in the accompanying drawings.

Figure 1 is a sectional elevation and Fig. 2' is a plan of,the whole apparatus, both figures showing also details of the first and second cellsand the special anode. Fig. 3 is a sectional elevation (taken on the line A, B, Fig.4) and Fig. 4 is a plan of the main casting constituting the base of the apparatus represent like parts.

The casting 3- (preferably of steel) has two circular cells constituting the. lower or alloy-containing portion of the first and secondcells 1 and 2 respectively as well as the reservoir or receptacleand the channels of communication 5, 6, ,.7 and 8. There is a lining l of refractory (basic) material for the inner part of the first cell 1. The alloy passages 5, 6, 7 and 8 widen out andalso constitute the reservoir or storage receptacle for the working alloy. Weirs 9 and 10 are provided oQer which the alloy flows from the respective cells wherein the level is main tained constant. The weir in the second cell is placed within the cell and on either Any suitable pumpsuchas rotating worm pumps 11 and 19 may be employed forthe circulation of '15 of enameled-iron or for the exterior gases through which also a current of air is continually drawn to avoid escape of any gases into the operating room. The second cell 2 like the first cell 1 is bolted tothe steel casting 3. The construction of the second cell may be different in each case according to the particular product which is to be manufactured from the alloys. A copper conductor 18 of large cross-section gives rise to the'magnetic field. A resistance coil 24 is arranged below the main casting Fig. 1, by means of which the under and outer parts and reservoir of the apparatus, together with the second cell and the metal outer container of the first cell, can be maintained at a constant temperature which will be approximatelythat of -the second cell. I prefer to heat the apparatus as aforesaid by the application of an alternating heating current to the aforesaid coil 24, which'i's supported by the well insulated masonry base of the apparatus.

25 arebeams upon which the apparatus is supported. The desired product, or, if the produced or .dissolved metal be reacted in situ, then the derived product, can be. removed by the pipe 26 and collected in the receiver 27 having an inspection device 28. From the receiver the product passes by the pipe 29 to the mold 30 which can be removed as and when desired. The cathode in the cell 2 is preferably constituted by small rods 31 of about l0 millimeters diameter carried by a plate 32 (preferably of copper) supported by tubes 33, or otherwise, the "said tubes being carried on bracketsv 34. The

aforesaid tubes 33 carrying the plate 32 can beadjusted to regulate the distance of the cathode from the anode and the extent of surface in contact with the electrolyte. The

small rods 31 are preferably arranged in circumferential rows: The product overflows the weir 35 and floats on the electrolyte and remains in the upper part of the collecting chamber 36, being there conveniently aggregated into a floating mass, while the associated electrolyte falls to the bottom of the said receptacle, or chamber, and, by

means of the passages 37, 38, passes to the pump 19, by which it is restored to the reservoir formed by the passages 5, 5, 6, 7.and 8.

The action of the apparatus is as follows: Either by artificial heat (preferably by the separate application of an alternating heat-,

ing current to a resister in the well insulated masonry base of the apparatus) orbyits own internalelectrically produced heat, the

under and outer part and reservoir of the apparatus together with the second cell and the metal outer container of the first cell tempermay be maintained at a constant that of ature .which will be approximately the second cell, namely from 300 to 500 according to the secondary reaccentigrade or the electro tions to be carried on there,

lyte in use, the lower temperatures being 750 centigrade) which is suitable for the melting and freely circulating conditions of the fused salt electrolyte.

When the pumpv 11 is set in motion the flow of the alloy is as follows: From the passages 5 it is delivered by the aforesaid pump into the body of the second cell 2 over the top of the pump casing and flows to the other side of the said cell 2 andover the weir 10 and thence through the opening 10 into the passage 5' and through the opening 4 into the cell 1. From here the alloy flows through the opening 6 andout over the weir 9 into the general reservoir constituted by the passages 5, 6, 7 and 8.

The advantages of this construction are many. The intermediate reservoir provides flexibility in bulk of the alloy so. that when the alloy becomes too poor in alkali metal, shrinkage of bulk only occurs in the inter: mediate reservoir andnot in the cells, and therefore the working of the process is not disturbed thereby.f The disposition of the reservoir and passages aroundand between the respective cells as shown also provides an admirably graded temperature slope befreshly melted and continuously renewed ,sodiu'm chlorid,.the additional yes'sel may be such as shown in Fig. 8. The sodium chlorid which is to form the raw material for the electrolysis is first melted in a separate vessel 20, Fig. 8, which is heated internallyiby the electric current supplied to I the electrodes 21, 22," the contents of the vessel 20 being preferably agitated or caused to rotate by the influence of an electric current I h on as above suggested with a separate receptacle in' which the triple alloy is reacted on by passing through the c'oil'23 contained within a magnetic steel casing 44. The sodium chlorid is preferably melted in contact with the alloy containing both sodium and potassium which has just been produced in the first cell.

1 do not confine myself to the precise construction of apparatus described and illussecond cell 2 according to any known or suitable methods but preferably as described in my copending applications Serial Numbers 683,376; 683,377 and 683,378 of even date herewith. lVhat I claim is p I 1. Electrolytic apparatus of thecharacter described, comprising two cells adapted to maintain a body of alloy at constant level .therein, a passage between said cells, an intermediate reservoir to take up variations in the bulk of the body of the alloy and means separating said reservoir'from each of said cells, substantially as described.

2. Electrolytic apparatus of the character described, comprisin two communicating cells adapted to maintain a body of alloy at constant level therein and supernatant electrolytes of. different characters in the respective cells, havingreversible reactions with the, alloy therein, and means in the firstcell, for agitating the electrolyte therein to facilitate the said reversible reactions between the primary electrolyte and the alloy in said cell, substantially as described.

3. Electrolytic apparatus of the character described, com'prisingtwo communicating cells adapted to maintain a body of alloy at constant level therein, in combination with an intermediate reservoir to take up variations in the bulk of the body of the alloy, together with means surrounding the first cell for setting up a magnetic field therein to cause a rotary motion in. the.

alloy, for the purpose described.

4. Electrolytic apparatus of the character described, comprising two communicat ing cellsadapted to maintain a body of alloy at constant level therein and supernatant electrolytes of different characters,

having reversible reactions with the alloy, and means surrounding the first cell and in the interior of the casing thereof, for agitating the electrolyte therein to facilitate the said reversible reactions between the electrolyte and the alloy in said cell, substantially as described. I a c 5. Electrolytic apparatus of the character described, comprising two communicating cells adapted to maintain va body of.

alloyat constant level therein, in combination with an intermediate reservoir to take up variations in the bulk of the body of the' off said product in a' pure condition without completely closing the cell.

6. Electrolytic apparatus -.o'f ter described, comprising two communicating cells adapted'to maintain a body of alloy at constant level therein, in combinathe charaction with an intermediate reservoir to take up variations in the bulk-of the body of the.

separating said reservoir from each of-said cells. and a refractory heat insulating lining in the lower portion of the first cell, for the purpose described. I v

8. Electrolytic apparatus of the type described, comprising an integral cast ng forming the base thereof and comprising the lower portions of two cells, an intermediate reservoir, connecting passages be tween the cells and reservoir and weirs.in said passages, substantially as described.

In testimony whereof I have signed my name to this specification in the presence of two subscribing witnesses.

, EDGAR ARTHUR ASHCROFT.

\Vitnesses:

' ULYssEs J. BYW'ATER,

PAUL Alums.

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