US2423351A - Apparatus for amalgam decomposition - Google Patents

Description

July l, 1947.

M. c, TAYLOR APPARATUS FOR AMALGAM DECOMPOSITION Filed Feb. l, 1943 2 Sheets-Sheet 1 f 5 d ma ,n MM M ma @fm mum MW la e Y 0% Q n m( M OM M M,

July l, "1947? M. c. TAYLOR 2,423,351

APPARATUS FOR AMALGAM DECOMPOSITION Fi1ed Feb. 1, 1943 La sheets-sheet 2 d70/mie or Patented July 1, 1947 UNITED 'STATES PATENT O'l'-'SF.l.C;-E

2,423,351 *APPARATUS Fon BECOMPOSITION Maurice C. Taylor, Ll`Iiagara1Falls,V 5N. Y1assign or to The Mathieson Alkali Worksflnc., New York, N. Y., a-corporationjof Virginia v'1 Claim.

This inventionis concernedwith the decomposition `'of .alkali metal amalgam in :the .presence of wateror an alcohol having less thaniourfcarbon atoms .to lform 'alkali metal hydroxide 'or alcoholate.

VI yhave discovered that the decomposition of amalgam `of v:sodium potassium or lithium with water or ralcohols having less vthan *.four carbon atoms is .facilitated to .af-'pronounced rdegree if the amalgamand. the water 'or alcohol 'arepassed through a tower containinga decompositionselectrode inlthe formof afpacking Aof electricallyconductive material with which A'mercury does not amalgamate :substantially and which is vpreferentially wetted `by :the water or alcohol, under conditions such that the water or alcohol .forms a y'thin :movin-g ,film non hthe .packing and travels counter-current to the amalgam 'through :the tower.

.;As .describedin :myrcopen'ding kapplication Serial No. 378,91?? filed February y14, :1941, .now IPaterit 2,336;045,iofwhich this 'isfafcontinuationin part,

my invention contemplates .(in a'lprocess :involving :reaction of alkalimetal from .amalgamwith a liquid selected from thegroup consisting 1vor water and alcohols.havingfless than four Acarbon atoms .per molecule) :the improvement which comprises passing the 'amalgam and liquid '1in counter-current contactwith .each .other through a space containingan electrode in the form .of la packing vof .electrically conductive material with which mercury or theramalgam does A.not Aamalgamate -substantially and which .isapreferentially wetted by the liquid :so that the liquid lforms .a thin .moving lm lon the packing, the .space in the packing, eXCeptfor that voccuiziiedloy.theit'hm lm, being substantially lled by a .pool of mer cury'or the amalgam. Preferably, the packing .is in 'such form :that itprovides =a..plura'lity of tortuous .passages or channels, the walls of which are defined by the packing itself. In operating this process, the liquidpreferably is passed :upwardlyin the tower while the amalgam is vpassed downwardly, and improved results `are obtained if the packing is flooded by a downwardlymoving stream of mercury or amalgam throughwhich the liquid passes in countercurrent.

YMy invention further contemplates, inapparatus =for reacting alkali metal from an amalgam thereof with a liquid yselected from the group consisting'of'water and alcohols having less than four carbon atoms per molecule, the combination which comprises a tower, an Yelectrode disposed in vthe'tower and consisting'of packing providing a plurality of passages through the tower and formed fof electrically conductive :material with which mercury 'does not amalgamate substantially `and which isfprefer'entially wetted by the liquid, means `for-admitting the amalgam and thefliquidto theitower, means (suchasa bottom in the tower) for maintaining a pool offmercury or amalgam in vthepassa'ges through the tower and ymeans for 'withdrawingthe ...products of the reaction of 'the amalgam andthe liquid Ifrom the tower. AThe packing, -`conveniently, 'may be of graphite. Preferably, ithe amalgam :is admitted to @the 4tower adjacent the top thereof while the liquid fis admitted 'adjacent the bottom kof -the tower. Themercur-y in suchcasefshould be withdrawn'from'anfintermediateportion of the ftower, preferably-through avconduitthe outlet of which is s'ubstantiallylower thantheinletof the conduit for mercury into the tower. The `conduit for withdrawing hydrogengas preferably communicateswithithewtowerfadjacent'the-top-thereofand the yconduitv employed f or withdrawing the liquid product of the alkali-metal-and-the liquid (alkali metal hydroxide ror alcoholate solution) -preferably communicates with the tower near the ltcp thereof, above `the level at -lwhich the mercury iis withdrawn. Y

fIn-thepreferred for-m 'ofm'y apparatus, therel is an Aannularvchamber around -the =-upper portion of thetower. Communication lbetween'ths annular chamberand the towerfisaforded by vmeans of apertures in the tower Wall, at'three :or y'more different levels yor by `means `4rof 4elongated -slots extending fbetweenfthe .extreme levels. YWith such an apparatus'the amalgam may-flow from the annular chamber into the tower through the lowest'o'f theth-ree flevels, with hydrogen fiiowing from the vtower into the chamber at the uppermost level andfwithLhydroxicie or alcoholate solution vflowing A.into the -annular chamber at an intermediate flevel.

A vpreferred Vpractice -of `my invention is described in detail hereinafter with reference'to the accompanying Figure 1 which is a diagrammatic vertical section of "a tower through which `sodium amalgam and "water arepa'ssedin countercurrent.

Fig. 2 .illustrates amodifled form Ao'f 'the apparatus of Fig. Y1 provided with an improvedm'eans for withdrawing mercury.

"Fig. 3 illustrates a modication of the appa'- ratus of Fig. v1 in which the communication between lthe towerand the "annular chamber surrounding itat the top v'thereof is bymeans of vertical *screened slots instead'of through rows 4of apertures at i different levels.

Fig. Ilillustrates a'modication of theappara- 3 tus of Figs. 1 and 3 in which the amalgam is introduced through a downcomer disposed at the center of the tower and provided with a cleanout, the iow of amalgam and liquid being, in general, concurrent.

Fig. illustrates a modification of the apparatus of Figs. l to 4, provided with means for compressing the packing in the tower.

Fig. 6 illustrates a modification of the apparatus of Fig. 5.

The tower of Fig. 1 comprises a vertically disposed shell I, preferably of uniform cross section. The shell may be constructed of any material that is not attacked by the materials passing therethrough, Thus, the shell maybe in the form of a hollow cylinder of iron or ceramic closed at both ends. throughout'with electrode material II that is be, together with hydrogen gas.

The shell is packed electrically conductive, non-amalgamating and preferentially wetted by the water or alcohol.

` Graphite isa suitable material and in the apparatus illustrated the packing` is formed of irregular shaped pieces of graphite about V8 inch in size. The interstices between the pieces form a plurality of tortuous passages from top to bottom of the tower. Y

`The upper portion of the tower is surrounded by a closed annular chamber I2 that communicates with the interior-through three rows I3, I4, I5 of'holes drilled through the shell at different elevations. f llhe holes are smaller than the pieces of packing and, conveniently, may beabout Tae or 3% inch 'in diameter. A conduit I8 for introducing sodium amalgam to be decomposed is connected to the annular chamber near the bottom thereof adjacent the lowermost row I3 of the holes. -A second conduit II for withdrawing the product (say, sodium hydroxide solution) Yis connected to the sideeof the annular chamber at approximately the level of the intermediate row I4 ofholes and a third conduit I8 for withdrawing hydrogen is connected to the top of the annular chamber above the upper row i5 of holes.

The liquor (say, water) to be reacted rwith the amalgam is introduced into the bottom of the tower Ythrough an inlet pipe I9. The liquid must be introduced under a pressure suiiicient to overcome the head of the contents of the tower and a pump (not shown) may be employed to force the liquid into the tower. f

Mercury from which the sodium has been removed iswithdrawn from the lower portion of the tower through a riser pipe that passes upwardly through the tower to a point below the annular chamber and thence through the shell. An inverted distributor cone 2I is disposed below the riser and attached thereto by a spider 22. The cone serves as a seal to prevent water from entering the riser and leaving with the spent amalgam and as a distributor to cause the water entering through the inlet pipe I9 to spread throughout the cross section of the tower.

In the operation of the apparatus, sodium amalgam from an electrolytic cell, not shown, or other suitable source is admitted into the lower portion of the annular chamber and flows through the lowermostl holes into the interior of the tower. Sufcient amalgam is introduced into the tower to submerge a predominating portion of the mass of packing material. Water or alcoholris forced into the bottom of the tower under pressure suii'icient to overcome the head of amalgam in the tower. The water or alcohol 4 is lighter than the amalgam and mercury and tends to rise in the tower countercurrent to the amalgam flow. Reaction takes place between the amalgam and the water or alcohol so that as the amalgam travels down the tower it loses its sodium content until it is substantially mercury and, as such, is withdrawn through the riser. The reaction between the water or alcohol and the sodium of the amalgam produces sodium hydroxide or sodium alcoholate, as the case may The hydrogen gas and the resulting solution of sodium hydroxide in water or sodium alcoholate in alcohol both rise toward the top of the tower. The hydrogen rises to the uppermost-row of holes and passes therethrough into the upper portion of the annular chamber from which it is withdrawn.

Sodium hydroxide or alcoholate solution passes through the intermediate row of holes into the annular chamber and thence is withdrawn into the conduit provided for this purpose.

Since the water or alcohol preferentially wets the surface of the graphite electrode packing, Vit follows a path which takes the form of an upwardly moving thin lm of solution on the electrode surfaces. This film moving up through the submerged mass of packing in the tower decom` poses the amalgam in a most efficient way since the film is continuously replenished.V The violent evolution and. rise of hydrogen inside the tower tends to carry the amalgam as well as the other fluids in an upward direction. However, this tendency may be overcome by employing a tower of relatively large cross section in order to give more space for the escape of hydrogen or by increasing the head of amalgam on the tower.

The means provided for withdrawing the mer.. cury from the tower is particularly suitable since it insures that a predominating portion of the tower packing will always be flooded with mercury or amalgam. The height of the sodium amalgam inlet above the mercury outlet represents the head required to force the amalgam countercurrent through the rising hydrogen and solution of hydroxide or alcoholate.

Fig. 2J which is a fragmentary vertical section through the lower portion of a tower similar to that of Fig. 1, shows a preferred means for withdrawing mercury from the tower. Water or alcohol to .be reacted with the amalgam is, as in the case of the apparatus of Fig. 1, introduced into they tower through the inlet pipe I9 in the bottom thereof and is distributed throughout the tower cross section by the inverted cone 2l disposed immediately above the inlet and held in position by braces 23, 23A attached to the bottom. An annular jacket 24 is disposed around the lower portion of the tower. Mercury enters this jacket through a row of holes 25 in the upper portion thereof and is withdrawn through an upwardly extending riser pipe 26 thatcommunicates with a lower portion of the jacket, which acts as a seal to prevent the water or alcoholate from escaping with the mercury. Otherwise, the apparatus partially illustrated by Fig. 2 is the same as that of Fig. 1.

Referring now to Fig. 3, it will be observed that the apparatus illustrated is the same as that of Fig. l, except that a series of vertical slots SI, 32, 33, 36, 35, 33 are provided around the periphery of the tower in place of the Ythree rows I3, I4, I5 of holes. Thus, the vertical'slots extendfrom the level of the holes I3 .to theV level of the holes I5, and are covered with fine screen graaien-i l g ,ifres'ifieetively,` for-the riiov ment gen,liduid-and-amaigam-er-nier havef infront ofthernf-------4 Y *4f The apparatus Vofllig. dissimilar to the apparatusof Figs. 1 and 3, except in the following particulars: Tlhe amalga rom the ,cfelljfineV stead-off being' admitted' 4to M annularl'cha'mber I2 throghthe Apipe -l 6; is admitted-into the tower through a downcomer pipe 40 which is sealed into the top of the tower and passes downwardly and centrally therein to the distributor 2| which is fastened to the downcomer 4!) by the spider 22. The top of the downcomer is covered by a removable clean-out cap 4l, and a-horizontally extending branch 42 of the downcomer is provided for admitting sodium amalgam thereto. The amalgam flows into the tower through the downcomer and thence rises concurrently with the water or alcohol introduced at the bottom of the tower. As the amalgam rises, it gives up its sodium and becomes mercury which flows through the slots Sl-SG into the annular chamber and is withdrawn from this chamber through the conduit I6, which in this case acts as a mercury outlet.

The apparatus of Fig. 4 has the advantage of easy cleaning, in addition to the fact that the mercury passing through the downcomer is in countercurrent heat exchange relation with the rising column of liquid and mercury or amalgam in the tower.

It should be noted that in practically every case the packing will have speciiic gravity lower than that of the mercury or the amalgam, so that there will be a tendency to buoy the packing upwardly. If the packing is composed of a plurality of pieces, which is the more convenient form, it should have suiicient mechanical strength to resist crumbling and should be so conned in the tower that it will not crowd into the upper portion thereof to the extent that it interferes with flow through the tower.

Unless the packing is held rrnly in place in the tower, the evolved hydrogen as it rises in the tower tends to grind together the pieces of packing and produces fines which may clog the tower or pass out through the upper portion thereof. This effect is more noticeable when the tower is employed for the production of sodium hydroxide than when it is employed to produce alcoholates, but in either case it is highly desirable that the packing be held rmly and tightly in the tower. This can be accomplished by providing the tower with means for compressing the packing therein. One such means is illustrated in Fig. 5, which illustrates a modification of the apparatus of Figs. 1 and 4.

Referring to Fig. 5, it will be seen that the shell I is provided with a movable bottom 5U. An internal flange 5| around the lower edge of the tower wall is provided with a series of threaded adjusting screws 52, 53, 54. These screws, when turned in the proper direction, force upwardly the movable bottom which is provided at its edges with suitable gaskets (not shown) or is fitted to the wall tightly enough for sealing purposes. As the bottom is pushed upward the packing in the tower is compressed and is held rmly in position so that it does not tend to be ground Figdiillustr-ates y'ai#modi-lied form of the apparatus of Fig.v5, provided with improved sealing means at the bottom.` As in the `apparatus of Fig. g5'. the distr ibutorf2 I ,is fastened to the movable bottom plate 50 by uprights 23,-23A- The inlet pipe v,I94 projects upwardly through a central aperture inthe movable bottom 5U and the movable-bottom may be forced upward by means Yof screws 52,153, 5A threaded thr ough the'fsbottom 60; e'lllefheads AVof the. screws --are covered'l by nipples 6|, 62, 63 closed by threaded caps 64, 65, 66, so that the entire bottom of the structure may be sealed after adjustment. Otherwise the apparatus of Fig. 6 is the same as that of Fig. 5 and operates in the same manner.

I claim:

In an apparatus for reacting alkali metal from amalgam with a liquid selected from the group consisting of water and alcohols having less than 4 carbon atoms per molecule, the combination which comprises a tower having apertures arranged in horizontal rows near the upper end thereof, an annular chamber extending around the exterior of the upper portion of the tower, said apertures providing communication between the tower and the annular chamber at levels adjacent the lower portion of said annular chamber, the upper portion of said annular chamber and the intermediate portion of said annular chamber, an electrode disposed in the tower and consisting of a mass of packing providing a plurality of tortuous passages through the tower and formed of electrically conductive material with which mercury does not amalgamate substantially and which is preferentially wetted by the liquid, a conduit communicating at its outlet end with the lower portion of said tower for admitting the liquid to the tower adjacent the bottom thereof, a second conduit communicating at its outlet end with said annular chamber at substantially the level of the lowermost row of said apertures for admitting amalgam to the upper portion of the tower, whereby the amalgam will iow downwardly through the tower and the packing material therein countercurrent to rising liquid introduced into the tower at its lower end, a third conduit for discharging from the tower mercury resulting from the decomposition of the amalgam, said third conduit having its inlet end communicating with said tower near the lower end thereof, said third conduit also having a portion thereof disposed at a level below the outlet end of said second conduit but above the position occupied by a major portion of said packing material, whereby in operation a major portion of the mass of packing material is automatically maintained submerged in a pool of the amalgam and mercury resulting from the decomposition of the amalgam, baffling means disposed opposite and below the inlet end of said third conduit to form a seal whereby the liquid admitted to the lower portion of said tower is prevented from entering the inlet end of said third conduit, a fourth conduit communicating at its inlet end with said annular chamber at a point adjacent the upper end thereof for removing hydrogen gas from the upper portion of the tower, and a fifth conduit communicating at its inlet end with said annular chamber at a level intermediate the junctures of said second and fourth conduits with said annular chamber and at substantially the level of the intermediate row of said apertures, for withdrawing from the tower y7 the liquid products of the reactionv of the v`alkali Number metal and Said liquids. 739,140 1 MAURICE C TAYLQE. 2,090,727 i Y 1 4 1 g, Y '784,592

` REFERENCES -QITED 5 1,095,832 The. following references are of record` in Vthe le of this patent. v f K 586:635

` Y UNITED STATES PATENTS Number Name l Y Date 10 652,861 Entz July s, 1900 Numgefgg 2,089,648 Gerke June 15,1937 Y, 6 431157 Name v Date Baker Sept. 15, 1903 Gosmafnnj. Aug. 24, 1937 Philipp Mar. 14, 1905 Friese May 19, 1914 McMillan Feb. .14, 1939 Taylor Dec. 7, 1943 Stormer July 20, 1897 FOREIGN PATENTS Country Date Great Britain 1891 Germany Mar. 30, 1937

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