US1851817A - Electrolytic apparatus - Google Patents

Description

} March 2-9, 1932. H. .H. DOW

' ELECTROLYTIC APPARATUS Filed Sept. 10, 1926 2 sheets sheet .Hdrerf #170? A T TORNE '6 March 29, 1932. H. H. DOW

ELECTROLYTIC APPARATUS 2 Sheets-Sheet Filed Sept. 10, I926 N y j 4///// P T 1 1 1 TTORNEYS Patent ed Mai, 29, 1932 UNITED. STATES PATENT OFFICE HERBERT H. DOW, OF MIDLAND, MICHIGAN,'ASSIGNOR TO THE DOW CHEMICAL COM- PANY, OF MIDLAND, MICHIGAN, A CORPORATION OF MICHIGAN ELECTROLYTIC APPARATUS Application filed September 10, 1926. Serial No. 134,649.

is lighter than the bath and due to the further factthat such metal readily ignites or burns upon exposure to the air, the problem of collecting and withdrawing the metal is attended with some. difiiculty as will be obvious.

that the metal thus collected may be kept out of dangerous contact with the air.

To the accomplishment of the foregoing and related ends, my invention then conslsts of the means hereinafter fully described and carried out.

I In said annexed drawings Fig. 1 1s a central vertical section of one form of my present improved electrolytic apparatus, and specifically of a cell for the electrolytic production of magnesium; Fig. 2 is a horizontal section and interior plan view of such apparatus or cell, the plane of the section being indicated by the line (22), Fig. 1; Fig. 3 is a side elevation of the cathode forming a part of the apparatus; Fig. 4 is a transverse section of a detail taken on the plane indicated by the line (44), Fig. 2; Fig. 5 is a central vertical section similar to that of Fig. 1, showing one-half of an apparatus of modified construction: and Fig. 6 is a similar sectional View showing still another modified form of construction.

The composition of the bath to be electrolyzed will, of course, vary in the first place with the metal which it is desired to produce, and in the second place, particularly in the electrolytic production of magnesium, as is well known, several different salts or compounds are available. The present apparatus, while designed more particularly for the electrolysis of magnesium chloride, is, it will be understood, adaptable for general use in thus producing so-called light metals whether from their chlorides or other compounds.

The molten bath is contained in a metallic vessel (1) which. as shown in the several figures or drawings, preferably takes the form ,of a cast iron or steel pot of approximately circular form in cross section, such vessel being provided with an outwardly directed flange (2) about its upper edge whereby the vessel may be supported in a suitable furnace chamber (not shown). Vessel 1) constitutes the cathode or at least is, connected as such in the electric circuit by means of a bus bar (3) that is attached to an extended portion of flange (2). The anode (4) which will be of carbon or graphite depends approximately centrally into the vessel and may be vertically adjustably supported in any well known manner, and also, of course, suitably connected in the electric circuit so that the current may be passed to the cathode through t-hebath in vessel (1) from said anode.

Supported within the vessel (1) is a cylindrical metal member (5) that surrounds but is spaced from the anode, said member being also spaced from the adjacent side wall of the vessel and so arranged that the electrolyte may circulate thercaround. This member is welded or otherwise so attached to the walls of vessel l) as to have good electrical connection therewith. The member, in other words, constitutes the effective electrode rather than the walls of the vessel, although the current to said member is supplied through the latter, as will be evident.

In the form shown in Figs. 1, 2, and 3, said cathode member (5) has an upper portion (5-a) that flares slightly outwardly, and the member is provided at its lower end with projecting feet 6) and adjacent its upper end with radially extending wings (7), by means of which feet and wings the member is attached, as above described, to the walls of the pot or vessel Suitably supported in the upper portion of the pot or vessel (1) is a downwardly opening chamber (8) of interrupted or uninterrupted circular form in plan, such chamber being located above the upper-end of cathode member so as to be adapted to collect the metal rising from the latter when the cell is in'operation. In the constructional form of the apparatus shown in Figs. 1 and 2, this chamber (8) is supported by having its outer edge rest on a plurality of circumferentially spaced blocks or bricks (9) of tire clay. that are in turn supported on brackets (10) fixedly secured to the side wall of vessel (1); and supported on a continuous flange (ll) above said brackets and bricks, and so above said chamber (8) is a circular ring (12) of tire brick or equivalent refractory material. such ring being arranged to receive a suitable cover (13) whereby the vessel (1) is closed when the apparatus is in operation. This cover will. of course. be suitably aper tured to permit the. passage therethrough of the anode t), and will also have an opening (14) for the escape of gas from the vessel and will have a remo able section located over the space between the ends of chamber (8) whereby access to the interior of thevessel may be readily secured. The chamber is itself formed with an opening (15) adjacent to the end. through which opening the metal which collects within the chamber may be removed by means of a ladle from time to time. There ma also be provided a smaller opening (16) through the. brick ring (12) through which gas accumulating underneath flange (11) may be vented or metal similarly accumulating may be removed.

In the moditied construction shown in Fig. .1. the principal difference lies in the shape of the cathode member (17) which is here more nearly cylindrical in form. i. e.. its sides are straight instead of flaring at the upper end of the member. In Fig. 6 the cathode member (18) again is shown as of more truly cylindrical form. but ditl'crs from both the preceding forms in that its lower end more closely tits against the wall of vessel (1). while said member on the other hand is pro vided with a series of vertically spaced openings (19) at various points about its circumference so as to permit ol' the tree circulation of the electrolyte around said member. In this form of the apparatu the chamber (2o) above the cathode is shown as supported in a somewhat different: manner. and in addition battles (21 and 2; are provided. one on each side of saidehamber. to assist in directing the flow of the circulating electrolyte about said chamber. All tln'ee'members (20.21 and 2:?) are electrically insulated from each other and the wall of chamber (1), as shown.

The operation oi" the apparatus is substantially the same in the case of each of the several forms thus shown and described. The molten electrolyte will till the pot or vessel (l) to a level lying above chamber (8) and will be replenished either continuously or from time to time so as to maintain such level approximately constant. As the lower end of electrode it) wears away. it will assume the form shown in dotted outline in Fig. l. and will preferably occupy the lower position there shown.

l'pon the passage of current through the apparatus where the cha-trolyte is a chloride. e. magnesium chloride, the chlorine is generated adjacent the outer surface of the anode (s and at the same time metallic magnesium in the form of tiny globules is lcleased adjacent the surface of the cathode member. The continuous stream of chlorine bubbles rising to the surface of the bath induces a strong upward tlow of the electrolyte in the space hetwccn the anode and the cathode. 'l'he cathode constitutes a battle wall or deflector to direct the tlow of the. electrolyte upwardly along the inner surface thereof and then returning downwardly in the space between the cathode and the wall of the pot, thereby setting up a well detined circulation of the bath. as indicated by the arrows. \Vhen disengaged from the *athodc surface, the globules of metal. being lighter than the electrolyte. are carried along by the upward current and rise toward the surface of the bath where they are entrapped within the collecting chamber 8. This result is accomplished without the necessity for interposing any curtain or screen between the active anode and cathode surfaces for separating the products therefrom. 'ithout the inner cathode member hcrein provided. no such regular circulation would take place. but on the other hand local eddy currents would be set up tending to oppose the upward tlow of the bath and to scatter the floating metal globules so as to hinder their collection in a chamber protected from contact with the evolved gases.

.\n outwardly Haring cathode is particularly advantageous in that the metal globules, which in rising tend to follow the cathode surface. are caused to move progressively turthcr away from the vicinity of the anode as they rise and hence can be more readily separated t'rom the anode product and collected without increasing the ctl'cctivc distance between the anode and cathode.

Whenever sutlicieut metal has accumulated within the chamber. it will be removed through the opening therefor provided, the chlorine or other gases passing olt through the. opening in the cover. as previously explained.

In addition to the operative advantages indicated above. it should be noted in conclusion that the use of a cathode member of the form and supported in the chamber in the manner described has the effect of substantially lowering the voltage of the cell by providing an unobstructed, generally horizontal path for the electric current between the electrodes.

Other modes of applying the principle of my invention may be employed instead of the one explained, change being made as regards the mechanism herein disclosed, provided the means stated by any of the following claims or the equivalent of such stated means be employed.

I therefore particularly point out and distinctly claim as my invention 1. In an apparatus for electrolyzing a fused magnesium compound, the combination of a vessel adapted to contain such electrolyte. a centrally disposed anode and a submerged cathode surrounding and horizontally opposed to said anode in spaccdrelation therefrom, thereby providing structed pathway through the electrolyte between said anode and cathode, said cathode also being spaced from the side-wall of said vessel and constituting a battle for directing thecirculation of the electrolyte therein.

2. In an apparatus for electrolyzing a fused magnesium co1npound,-the combination of a vessel adapted to contain such electrolyte. a centrally disposed anode. and a sub merged cathode surrounding and horizontally opposed to said anode in spaced relation therefrom, thereby providing an unobstructed pathway through the electrolyte between said anode and cathode. said cathode also being spaced from the side-wall of said vessel and constituting a bailie for directing the (irculation of the electrolyte therein. and a downwardly opening trough-like chamber sealed by the electrolyte and located above said cathode for collecting the metal rising therefrom.

3. In an apparatus for electrolyzing a fused magnesium compound. the combination of a vessel adapted to contain such clectrolyte. a centrally depending anode and asubmerged cathode surrounding and horizontally opposed to said anode in spaced relation therefrom. thereby providing an unobstructed pathway through the electrolyte between said anode and cathode. said cathode being electrically connected with said vessel and forming a battle for directing the circulation of electrolyte therein. and a downwardly opening trough-like. chamber sealed by the electrolyte and located above said cathode for collecting the metal rising therein.

4. In an apparatus for electrolyzing a fused magnesium compound, the combination of a vessel adapted to contain such electrolyte, a centrally depending anode and a submerged cathode surrounding and horizontally opposed to said anode in spaced relation therefrom, thereby providing an unan unobobstructed pathway through the electrolyte between said anode and cathode, said cathode being electrically connected with said vessel and forming a baflle for directing the circulation of electrolyte therein, and a downwardly opening chamber of interrupted annular t'orm sealed by the electrolyte and located above said cathode for collecting the metal rising therefrom, said chamber being spaced from said anode and the vessel. wall, the opening between the ends thereof permitting access to the interior of said vessel and said chamber being provided with an opening for the removal of metal therefrom.

5. In an apparatus for electrolyzing a fused magnesiu1n compound, the combina tion of a vessel adapted to contain such electrolyte, a centrally depending anode and a submerged cathode in generally vertical position but flared outwardly at the upper end thereof surrounding and horizontally opposed to said anode in spaced relation therefrom, thereby providing an unobstructed pathway through the electrolyte between said anode and cathode. said cathode being electrically connected with but spaced from the side-wall of said vessel and forming a battle-for directing the circulation of electrolyte therein and a downwardly opening trough-like chamber sealed by the electrolyte and located above said cathode for collecting the metal rising therefrom.

6. In an apparatus for elcctrolyzing a fused magnesium compound, the combine tion of a vessel adapted to contain such electrolyte, a centrally depending anode and a submerged cathode in generally vertical position but flared outwardly at the upper end thereof surrounding and horizontally opposed to said anode in spaced relation therefrom, thereby providing an unobstructed pathway through the electrolyte between said anode and cathode. said cathode being electrically connected with but spaced from the side-wall of said vessel and forming a battle tor directing the circulation of electrolyte therein and a downwardly opening chamber of inter rupted annular form sealed by the electrolyte and located above said cathode for collecting the metal rising therefrom, said chamber be ing spaced from said anode and the vessel wall, the opening between the ends thereof permitting access to the interior of said vessel and said chamber being formed with an opening for the removal of metal therefrom.

Signed by me this th day of August,

HERBERT H. DOW.

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