US2545376A - Electrolytic cell with mercury cathode - Google Patents

Description

March 13, 1951 R. M. R. ORNHJELM ELECTROLYTIC CELL WITH MERCURY CATHODE Filed Oct. 6, 1947 IN VE N TOR PuA/HR MFIUE/ TZ )QHFHEL sso/v QQNHJELM HTTOQNEX Patented Mar. 13, 1951 r,

ELECTROLYTIC CELL WITH MERCURY CATHODE Runar Mauritz Rafaelsson firnhjclm, Kuusankoski, Finland, assignor to Kymin Osakeyhtiii- Kymmene Aktiebolag, Kuusankoski, Finland Application October 6, 1947, Serial No. 778,136

In Finland ctober22, 1945 Section uremic Law 690, August 8, 1946 Patent expires October 22, 1965 3Claims. (cram- 250) I The method of constructing electrolytic cells with mercury cathodes from rolled section iron is previously known. As the cell is generally trough shaped, U or I-shaped balks are mostly used. In the event that very large cells are constructed they may comprise a separate bottom part with upright walls attached in a convenient manner to'the edges of the said bottom.

It is likewise previously known that the walls of such cells are lined with a chlorine gas resistant material such as rubber, artificial resin or plastics, acid proof enamel, or some other substance convenient for that purpose, and that the bottom of the cells is unlined because it is covered with a mercury film. i

It is essential that this film of mercury, although covering the unlined bottom of the cell completely, be as thin as possible thus saving considerable quantities of mercury.

The main defects of the present cells constructed of rolled sectioniron are, firstly that during usage, when there isa certain consumption of mercury, bare regions appear on the bottom of the cell. In order that the formation of 'such bare regions be prevented the mercury film that is used as a cathode must be kept unnecessarily thick which, again, is uneconomic. This, however, is inevitable because otherwise hydrogen gas will develop on the bare regions resulting in a possible explosion. Furthermore, the bottom of the cell will corrode in the said bare places. The second notable defect is thatthe flowing speed of mercury in the present cells decreases at the edge between the bottom and the upright walls which decrease causes solid sodium amalgam to form at the edges of the mercury film during the electrolytic action. The said amalgam then begins to decompose and forms hydrogen gas. This amalgam coating also causes an accumulation of carbon particles and other impurities which render the circulation of mercury more difficult. All these disturbances in the usage of the cell make it necessary to take the cell apart for cleaning. The aforementioned defects can be regarded as very great especially when large cells of for example '10 to 12 meters in length are used, the strength of the current being 10,000to 20,000 amperes, because the. said disturbances may cause serious accidents and injuries. To prevent this the bottoms of the described cells are completely covered with a rubber coating through which the necessary electrodes are passed. This bottom coating is not very lasting, however, and thus a cell/ of the said type has proved to be uneconomic.

, The object of this invention is to eliminate the'said defects even when thelargest type'bf barebottomed cells are used. The invention is based on the observation that the reason for the aforementioned disturbances lies therein that .the bottom of a cell manufactured from-rolled section iron is never completely level but "always just enough curved or-bent to necessitate the use of too much mercury because a theoretically sufficient thin film does not cover the bottom of the cell due to the great cohesive hold of the liquid, which fact has not previously been-taken into consideration when constructing cells; It has also been observed that the decrease in-the flowing speed of mercury is due to the; fact that the edge between cell bottom and walls that are manufactured by the rolling process is rounded.

Furthermore similar disturbances have been observed even in the smallest angles and uneven surfaces resulting from the rolling process. Contrary to previous beliefs the originators of the disturbances that have occurred when cells manufactured by the rolling process have been replanedare continually the faults in the form of the cell. v

In conformity with the invention the described disadvantage is eliminated by accurate machining of the shaped plate, from which the respective cell bottom is made, so that the upper. surface is planed to an absolute level. Likewise the edge between bottom and walls is machined to right.

rounded edge is eliminated.- I

An accurately machined bottom surface effects a considerable saving'of mercury because the thickness ofthe mercury -film' in the invented cell under reference can be kept even and so thin that the bottom of the-cell is just merely covered su fiiciently. The degree angle -between the walls and the bottom guarantees that no disturbing amalgams'c an formulate at-that region and also that thesaid region does -not become uncovered. 4

In conformity with an especially favorable modification of the said invention the edges of the bottom that touch the sidewalls; may be equipped with an encircling channel-or trough angles with a fully developed edge, i. e. -.the

which can be made by conveniently machining the respective edges of the shaped bottom plate. By this measure an even more effective means of preventing the edge-surface of the mercuryfilm from developing harmful phenomena. is gained because the mercury flows with greater speed v at the'edges than on otherregionsof thebottom surface.

formed of material impervious to the decomposition products of electrolyte, said lining being secured to and covering said side walls and including a lower edge portion turned into and terminating within said edge groove, a securing strip overlying said turned portion of said lining, said securing strip being, received within said edge groove and having its upper surface lying below said machined surface.

2. An electrolytic cell with a mercury cathode comprising, a trough formed of iron, said trough being generally U-shaped in cross section with the base of the u forming the bottom of the trough being accurately machined throughout to form an even flat upper surface, said upper surface and the side walls of said trough extending at exact right angles with respect to each other and said upper surface meeting the side walls of said trough at a definite edge, said machined upper surface being grooved along its edges adjacent said side walls, said side walls being provided on their interior surfaces with a protective lining impervious to the decomposition products of electrolyte, the lower end section of said lining extending down below said machined bottom surface of said cell and being turned to terminate in said edge groove with the upper surface of the turned portion of said protective lining lying below said machined upper surface of said bottom, and a securing strip seated insaid groove to overlie said turned portion of said protective lining, said strip wholly covering said turned portion and securing said turned portion in place in said groove with the upper surface of said securing strip extending no higher than said machined surface.

3. An electrolytic cell with a mercury cathode comprising an iron structure, formed with a horizontally extending center web and with side walls extending upwardly with respect to said center 6 web, said web and said side walls forming a trough, the bottom of said trough being accurately machined throughout providing a smooth flat surface to meet said side walls at a definite edge, said machined surface and said side walls extending at right angles to each other, said machined surface being, grooved along its edges adjacent said side walls, and a protective lining of material impervious to the decomposition products of electrolyte, said lining being secured to and covering said side walls, saidlining including a lower edge turned into and terminating within said edge groove, a strip overlying the turned edge of said lining and received within said groove to hold said turned edge tightly in place in said groove, and means to secure said strip in place with no part of the top thereof extending above the main portion of saidmachined surface. v RUNAR MAURITZ RAFAELSSON ('jRNHJELM.

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

UNITED sTATEs PATENTS Number Name Date 115,717 Dieterich June 6, 1871 259,864 Johnson June 20, 1882 1,030,490 Potter June 25, 1912 1,420,211 Paulus June 20, 1922 2,15%,830 Benker Apr. 18, 1939 2,316,685 Gardiner Apr. 13, 1943 2,334,354 Richardson Nov. 16, 1943 FOREIGN PATENTS' Number Country Date 21,935 Finland Aug. 29, 1947

Claims (1)

1. AN ELECTROYLTIC CELL WITH A MERCURY CATHODE COMPRISING AN INTEGRAL IRON STRUCTURE IN THE FORM OF AN I BEAM IN CROSS-SECTION WITH THE CENTER WEB OF SAID BEAM EXTENDING HORIZONTALLY, A TROUGH FORMED BY THE SAID CENTER WEB AND THE SAID SIDE WALLS PROVIDED BY THE UPWARDLY EXTENDING ARMS OF SAID I, THE BOTTOM OF SAID TROUGH BEING ACCURATELY MACHINED THROUGHOUT TO PROVIDE A SMOOTH FLAT HORIZONTAL SURFACE, SAID SIDE WALLS EXTENDING AT RIGHT ANGLES WITH RESPECT TO SAID SURFACE, THE BOTTOM OF SAID TROUGH BEING FORMED WITH A GROOVE BETWEEN SAID MACHINED SURFACE AND EACH OF SAID SIDE WALLS, A PROTECTIVE LINING FOR SAID SIDE WALLS FORMED OF MATERIAL IMPERVIOUS TO THE DECOMPOSITION PRODUCTS OF ELECTROYTE, SID LINING BEING SECURED TO AND COVERING SAID SIDE LWALLS AND INCLUDING A LOWER EDGE PORTION TURNED INTO AND TERMINATING WITHIN SAID EDGE GROOVE, A SECURING STRIP OVERLYING SAID TURNED PORTION OF SAID LINING, SAID SECURING STRIP BEING RECEIVED WITHIN SAID EDGE GROOVE AND HAVING ITS UPPER SURFACE LYING BELOW SAID MACHINED SURFACE.

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