EP0131977A1 - Process for eliminating mercury sludge layers from the bottom of mercury electrolysis cells, and process for elektrolysing an aqueous alcali metal halide solution in a mercury cathode cell - Google Patents
Process for eliminating mercury sludge layers from the bottom of mercury electrolysis cells, and process for elektrolysing an aqueous alcali metal halide solution in a mercury cathode cell Download PDFInfo
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- EP0131977A1 EP0131977A1 EP84200824A EP84200824A EP0131977A1 EP 0131977 A1 EP0131977 A1 EP 0131977A1 EP 84200824 A EP84200824 A EP 84200824A EP 84200824 A EP84200824 A EP 84200824A EP 0131977 A1 EP0131977 A1 EP 0131977A1
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- mercury
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- scraper
- sole
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- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
- C25B15/00—Operating or servicing cells
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- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
- C25B1/00—Electrolytic production of inorganic compounds or non-metals
- C25B1/01—Products
- C25B1/34—Simultaneous production of alkali metal hydroxides and chlorine, oxyacids or salts of chlorine, e.g. by chlor-alkali electrolysis
- C25B1/36—Simultaneous production of alkali metal hydroxides and chlorine, oxyacids or salts of chlorine, e.g. by chlor-alkali electrolysis in mercury cathode cells
Definitions
- the present invention relates to a method for removing a layer of coarse mercury from the bottom of cathode electrolysis cells formed by a film of mercury flowing over the bottom.
- the invention relates to a method for removing a layer of coarse mercury from the bottom of the electrolysis cells, the cathode of which is a film of mercury flowing over the floor, according to which a scraper is moved in the mercury film, , the displacement of the scraper being adjusted so as to permanently leave a residual film of large mercury of predetermined thickness adhering to the sole.
- the displacement of the scraper must be adjusted to detach only the upper part of the agglomerates of coarse mercury without altering the above-mentioned residual film which must be entirely immersed in the film of mercury.
- the optimum thickness of the residual film of coarse mercury to be maintained on the hearth depends on various factors related to the design of the electrolysis cell and to its mode of operation, among which we may notably mention the length of the cell, the slope of the sole, the profile of the anodes, the thickness of the mercury film, the distance separating the anodes from the cathode and the density of the electrolysis current. This optimum thickness can be easily determined, in each particular case, by routine research work.
- thicknesses which are suitable for the residual film of coarse mercury are those at least equal to 0.04 mm, and more especially those between 0.05 and 2.5 mm, the thicknesses between 0.15 mm and 1.5 mm being especially advantageous.
- Adequate adjustment of the displacement of the scraper in the mercury film can be effected by any suitable means.
- the front end of a flexible strip of specific weight less than that of mercury and designed to be partially immersed in the film of mercury is used for the scraper. so that its underside is spaced from the bottom by a distance equal to the thickness desired for the residual film of coarse mercury.
- the flexible strip is introduced into the cell and is pushed there into the mercury film parallel to the floor. While the strip is thus pushed from behind into the cell, the front edge of its anterior end detaches a surface layer of the clusters of large mercury from the sole.
- the choice of the thickness of the strip is conditioned by the need to give it both sufficient rigidity to be able to move it in the mercury film by pushing it from the rear. , and sufficient flexibility to allow it to pass under the anodes without damaging them.
- the choice of the optimum thickness of the strip depends on various parameters, in particular on the material of which the strip is made, its width and its length, itself linked to the length of the cell, and it can be determined in each case. particularly through routine research. For example, in the case of a strip about 10 to 20 m long, made of an organic polymeric material such as polyethylene, polypropylene or, preferably, a fluoropolymer, good results are obtained. results by giving the strip a thickness substantially between 2 and 5 mm.
- the aforementioned front end of the strip serving as a scraper, can possibly be reinforced or stiffened, for example by giving it a thickness greater than that of the subsequent part of the strip, and its front edge can be bevelled.
- the front end of the strip, which serves as a scraper is a pallet which has a front edge transverse to the longitudinal axis of the strip and two lateral edges arranged obliquely to this axis so to deviate from it backwards.
- the front edge of the pallet serves to detach the layer of coarse mercury and the lateral edges serve to separate the agglomerates of coarse mercury thus detached, during the movement of the strip in the cell.
- a strip is preferably used, at least the periphery of which is made of a material which does not conduct electricity, which makes it possible to keep the cell under tension while the strip is moved therein in mercury; the material used for this purpose can for example be a fluoropolymer such as polyvinylidene fluoride or polytetrafluoroethylene. Maintaining the spacing of the flexible strip relative to the floor can be achieved by sliding the strip against the underside of the anodes of the cell or against fixed guides.
- the maintenance of this spacing can be obtained by an appropriate adjustment of its specific weight by incorporating therein, for example, a core made of a dense material, or by electromagnetic attraction adjusted towards the floor, by incorporating therein a core made of a ferromagnetic material, usually an iron powder.
- the strip is introduced at one end of the cell and it is pushed there into the mercury film, towards the opposite end of the cell.
- the strip can be moved from the upstream end to the downstream end of the cell with respect to the direction of flow of the mercury film; however, it is preferred to operate the movement of the strip from the downstream end to the upstream end.
- the strip can advantageously be unwound in the cell from a drum placed near one end of the cell (for example its downstream end mentioned above) and, as soon as the anterior end of the strip has traversed the entire cell, moving it in the opposite direction, winding it again on the drum.
- this embodiment of the method it is possible to automate the successive and periodic alternating movements of the strip by coupling the drum to a motor whose operation is subject to a regulating device.
- This can be programmed to start automatically the drum motor at preset time intervals; as a variant, it may include a member for measuring the thickness of the layer of coarse mercury on the hearth and be programmed to automatically start the drum motor as soon as the thickness of this layer, measured by the measuring member, exceeds a predetermined critical value.
- the process according to the invention finds a particularly advantageous application in the case of cells with an approximately horizontal mercury cathode, usually used for the electrolysis of aqueous solutions of sodium chloride, and more especially cells of this type equipped with metal anodes. .
- the process according to the invention reduces the rate of formation of coarse mercury and, consequently, the frequency of cleaning of the sole; it also improves the regularity of the flow of the mercury film, which facilitates the control of the distances separating the anodes from the cathode, reduces the frequency and the importance of the adjustments of the position of the anodes with respect to the cathode and allows working with shorter anode-cathode distances.
- the invention therefore also relates to a method for the electrolysis of an aqueous solution of an alkali metal halide, for example sodium chloride, in an electrolysis cell the cathode of which comprises a film of mercury flowing over a metallic sole, according to which an adherent film of coarse mercury, between 0.04 and 2.5 mm thick, is permanently maintained on the sole.
- an alkali metal halide for example sodium chloride
- the film of coarse mercury it is generally advisable for the film of coarse mercury to cover the entire sole. Its optimum thickness depends in particular on the thickness of the flowing mercury film. This preferably has a thickness of between 2 and 5 mm.
- an aqueous sodium chloride solution was electrolysed in a cell with a mobile mercury cathode, of the V-200 type (Solvay & Cie) described in JSSconce's treatise "Chlorine, its manufacture, properties ans uses", 1962, Reinhold Publishing Corp., New York, pages 187 to 189.
- the cell was equipped with 180 anodes formed from horizontal titanium lamellae carrying an active coating formed by '' a mixture of ruthenium oxide and titanium oxide.
- the distance between the anodes and the cathode was set at about 2 mm, the flowing mercury film, forming the cathode, having an average thickness of about 3 mm.
- the anodes were first raised and then, from the downstream end of the cell, a flexible polytetrafluoroethylene strip containing a steel core and having an approximate length was introduced. 16 m and a thickness of about 4 mm, and it was moved in the mercury film, towards the upstream end of the cell. Due to its specific weight and its metallic core, the strip remained immersed by about 2 mm in the mercury film during its movement in the cell; it therefore tore off a surface layer of the agglomerates of coarse mercury present on the sole, allowing a residual film of coarse mercury about 1 mm thick to adhere thereto. After extracting the strip from the cell, the anodes were lowered until their spacing with respect to the mercury film was approximately 2 mm.
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Abstract
Description
La présente invention concerne un procédé pour éliminer une couche de gros mercure de la sole des cellules d'électrolyse à cathode formée d'un film de mercure en écoulement sur la sole.The present invention relates to a method for removing a layer of coarse mercury from the bottom of cathode electrolysis cells formed by a film of mercury flowing over the bottom.
Une difficulté importante rencontrée dans l'exploitation des cellules d'électrolyse à cathode de mercure, telles que celles généralement utilisées pour l'électrolyse de solutions aqueuses d'halogénure de métal alcalin, par exemple de chlorure de sodium, réside dans la formation intempestive et incontrôlée d'amas visqueux adhérant à la sole des cellules et dénommés habituellement "gros mercure" ou "beurre de mercure".An important difficulty encountered in the operation of mercury cathode electrolysis cells, such as those generally used for the electrolysis of aqueous solutions of alkali metal halide, for example sodium chloride, lies in the untimely formation and uncontrolled viscous clumps adhering to the bottom of the cells and usually called "coarse mercury" or "mercury butter".
La formation de ces amas de gros mercure adhérant à la sole des cellules d'électrolyse perturbe l'écoulement du film de mercure formant la cathode et impose de ce fait une surveillance permanente de la position des anodes et un ajustement périodique de leur écartement vis-à-vis du film de mercure, pour éviter la formation de courts-circuits fortuits. L'accumulation progressive de gros mercure sur la sole des cellules nécessite par ailleurs d'en nettoyer périodiquement la sole et on a proposé à cet effet de déplacer périodiquement un racloir sur la sole pour en arracher les agglomérats de gros mercure (brevet BE-A-881955 de Montedison SpA ; Central Patents Index, Abstracts Journal, Londres (Grande-Bretagne), abrégé 04648 W/03 : demande de brevet japonais 49098798 de Mitsubishi Chem.; idem, abrégé 91735 X/49 : demande de brevet japonais 76041040 de Mitsubishi Chem.). Dans ces procédés connus, le déplacement du racloir sur la sole de la cellule est réglé pour en éliminer chaque fois la totalité du gros mercure qui s'y forme.The formation of these clusters of large mercury adhering to the bottom of the electrolysis cells disrupts the flow of the mercury film forming the cathode and therefore requires permanent monitoring of the position of the anodes and periodic adjustment of their spacing vis- to the mercury film, to avoid the formation of accidental short circuits. The progressive accumulation of large mercury on the sole of the cells also requires periodic cleaning of the sole and it has been proposed for this purpose to periodically move a scraper on the sole to remove the agglomerates of large mercury (patent BE-A -881955 by Montedison SpA; Central Patents Index, Abstracts Journal, London (Great Britain), abstract 04648 W / 03: Japanese patent application 49098798 by Mitsubishi Chem .; ditto, abstract 91735 X / 49: Japanese patent application 76041040 by Mitsubishi Chem.). In these known methods, the displacement of the scraper on the bottom of the cell is adjusted in order to remove each time all the large mercury which is formed there.
On a trouvé maintenant qu'on pouvait améliorer le fonctionnement des cellules d'électrolyse à cathode de mercure et, notamment, réduire la fréquence de l'ajustement de la position des anodes, par un réglage approprié du déplacement du racloir dans la cellule.We have now found that we could improve the functioning of mercury cathode electrolysis cells and, in particular, reduce the frequency of adjustment of the position of the anodes, by an appropriate adjustment of the displacement of the scraper in the cell.
L'invention concerne à cet effet un procédé pour éliminer une couche de gros mercure de la sole des cellules d'électrolyse dont la cathode est un film de mercure en écoulement sur la sole, selon lequel on déplace un racloir dans le film de mercure, ,le déplacement du racloir étant réglé de manière à laisser en permanence une pellicule résiduelle de gros mercure d'épaisseur prédéterminée adhérant à la sole.To this end, the invention relates to a method for removing a layer of coarse mercury from the bottom of the electrolysis cells, the cathode of which is a film of mercury flowing over the floor, according to which a scraper is moved in the mercury film, , the displacement of the scraper being adjusted so as to permanently leave a residual film of large mercury of predetermined thickness adhering to the sole.
Dans le procédé selon l'invention, le déplacement du racloir doit être réglé pour détacher seulement la partie supérieure des agglomérats de gros mercure sans altérer la pellicule résiduelle précitée qui doit être entièrement immergée dans le film de mercure. L'épaisseur optimum de la pellicule résiduelle de gros mercure à maintenir sur la sole dépend de divers facteurs liés à la conception de la cellule d'électrolyse et à son mode de fonctionnement, parmi lesquels on peut notamment citer la longueur de la cellule, la pente de la sole, le profil des anodes, l'épaisseur du film de mercure, la distance séparant les anodes de la cathode et la densité du courant d'électrolyse. Cette épaisseur optimum peut être aisément déterminée, dans chaque cas particulier, par un travail de recherche de routine. En règle générale, dans le cas de cellules à pente modérée (par exemple de l'ordre de 1,5 à 15 mm par mètre courant de longueur, et plus spécialement de 6 à 10 mm par mètre), dans lesquelles le film de mercure a une épaisseur moyenne comprise entre 2 et 5 mm, des épaisseurs qui conviennent pour la pellicule résiduelle de gros mercure sont celles au moins égales à 0,04 mm, et plus spécialement celles comprises entre 0,05 et 2,5 mm, les épaisseurs comprises entre 0,15 mm et 1,5 mm étant spécialement avantageuses.In the process according to the invention, the displacement of the scraper must be adjusted to detach only the upper part of the agglomerates of coarse mercury without altering the above-mentioned residual film which must be entirely immersed in the film of mercury. The optimum thickness of the residual film of coarse mercury to be maintained on the hearth depends on various factors related to the design of the electrolysis cell and to its mode of operation, among which we may notably mention the length of the cell, the slope of the sole, the profile of the anodes, the thickness of the mercury film, the distance separating the anodes from the cathode and the density of the electrolysis current. This optimum thickness can be easily determined, in each particular case, by routine research work. As a general rule, in the case of cells with a moderate slope (for example of the order of 1.5 to 15 mm per running meter of length, and more especially of 6 to 10 mm per meter), in which the film of mercury has an average thickness between 2 and 5 mm, thicknesses which are suitable for the residual film of coarse mercury are those at least equal to 0.04 mm, and more especially those between 0.05 and 2.5 mm, the thicknesses between 0.15 mm and 1.5 mm being especially advantageous.
Le réglage adéquat du déplacement du racloir dans le film de mercure peut être opéré par tout moyen approprié. On peut par exemple, à cet effet, faire glisser le racloir sur des guides solidaires de la sole, qui maintiennent en permanence le racloir écarté de la sole d'une distance égale à l'épaisseur recherchée pour la pellicule résiduelle de gros mercure.Adequate adjustment of the displacement of the scraper in the mercury film can be effected by any suitable means. One can for example, for this purpose, slide the scraper on guides integral with the sole, which permanently keep the squeegee spaced from the sole by a distance equal to the thickness desired for the residual film of coarse mercury.
Dans une forme d'exécution préférée de l'invention, on met en oeuvre, pour le racloir, l'extrémité antérieure d'une bande flexible de poids spécifique inférieur à celui du mercure et conçue pour être partiellement immergée dans le film de mercure, de manière que sa face inférieure soit écartée de la sole d'une distance égale à l'épaisseur recherchée pour la pellicule résiduelle de gros mercure. Dans cette forme de réalisation de l'invention, la bande flexible est introduite dans la cellule et y est poussée dans le film de mercure parallèlement à la sole. Pendant que la bande est ainsi poussée, par l'arrière, dans la cellule, l'arête frontale de son extrémité antérieure détache une couche superficielle des amas de gros mercure de la sole.In a preferred embodiment of the invention, the front end of a flexible strip of specific weight less than that of mercury and designed to be partially immersed in the film of mercury is used for the scraper. so that its underside is spaced from the bottom by a distance equal to the thickness desired for the residual film of coarse mercury. In this embodiment of the invention, the flexible strip is introduced into the cell and is pushed there into the mercury film parallel to the floor. While the strip is thus pushed from behind into the cell, the front edge of its anterior end detaches a surface layer of the clusters of large mercury from the sole.
Dans cette forme d'exécution de l'invention, le choix de l'épaisseur de la bande est conditionné par la nécessité de lui conférer à la fois une rigidité suffisante pour pouvoir la déplacer dans le film de mercure en la poussant par l'arrière, et une souplesse suffisante pour lui permettre de passer sous les anodes sans les détériorer. Le choix de l'épaisseur optimum de la bande dépend de divers paramètres, notamment du matériau constitutif de la bande, de sa largeur et de sa longueur, elle-même liée à la longueur de la cellule, et elle peut être déterminée dans chaque cas particulier par un travail de recherche de routine. A titre d'exemple, dans le cas d'une bande d'environ 10 à 20 m de long, en un matériau polymé- rique organique tel que du polyéthylène, du polypropylène ou, de préférence, un polymère fluoré, on obtient de bons résultats en conférant à la bande une épaisseur sensiblement comprise entre 2 et 5 mm. L'extrémité antérieure précitée de la bande, servant de racloir, peut éventuellement être renforcée ou rigidifiée, par exemple en lui conférant une épaisseur supérieure à celle de la partie subséquente de la bande, et son arête frontale peut être biseautée. Dans une variante d'exécution, l'extrémité antérieure de la bande, qui sert de racloir, est une palette qui présente une arête frontale transversale à l'axe longitudinal de la bande et deux arêtes latérales disposées obliquement par rapport à cet axe de manière à s'en écarter vers l'arrière. Dans cette variante d'exécution de l'invention, l'arête frontale de la palette sert à détacher la couche de gros mercure et les arêtes latérales servent à écarter les agglomérats de gros mercure ainsi détachés, pendant le déplacement de la bande dans la cellule.In this embodiment of the invention, the choice of the thickness of the strip is conditioned by the need to give it both sufficient rigidity to be able to move it in the mercury film by pushing it from the rear. , and sufficient flexibility to allow it to pass under the anodes without damaging them. The choice of the optimum thickness of the strip depends on various parameters, in particular on the material of which the strip is made, its width and its length, itself linked to the length of the cell, and it can be determined in each case. particularly through routine research. For example, in the case of a strip about 10 to 20 m long, made of an organic polymeric material such as polyethylene, polypropylene or, preferably, a fluoropolymer, good results are obtained. results by giving the strip a thickness substantially between 2 and 5 mm. The aforementioned front end of the strip, serving as a scraper, can possibly be reinforced or stiffened, for example by giving it a thickness greater than that of the subsequent part of the strip, and its front edge can be bevelled. In an alternative embodiment, the front end of the strip, which serves as a scraper, is a pallet which has a front edge transverse to the longitudinal axis of the strip and two lateral edges arranged obliquely to this axis so to deviate from it backwards. In this variant In carrying out the invention, the front edge of the pallet serves to detach the layer of coarse mercury and the lateral edges serve to separate the agglomerates of coarse mercury thus detached, during the movement of the strip in the cell.
On utilise de préférence une bande dont au moins la périphérie est en un matériau non conducteur de l'électricité, ce qui permet de maintenir la cellule sous tension pendant qu'on y déplace la bande dans le mercure ; le matériau utilisé à cet effet peut par exemple être un polymère fluoré tel que du polyfluorure de vinylidêne ou du polytêtrafluoréthylène. Le maintien de l'écartement de la bande flexible par rapport à la sole peut être réalisé par glissement de la bande contre la face inférieure des anodes de la cellule ou contre des guides fixes. En variante, le maintient de cet écartement peut être obtenu par un réglage approprié de son poids spécifique en y incorporant par exemple une âme en un matériau dense, ou par attraction électromagnétique réglée vers la sole, en y incorporant une âme en un matériau ferromagnétique, généralement une poudre de fer.A strip is preferably used, at least the periphery of which is made of a material which does not conduct electricity, which makes it possible to keep the cell under tension while the strip is moved therein in mercury; the material used for this purpose can for example be a fluoropolymer such as polyvinylidene fluoride or polytetrafluoroethylene. Maintaining the spacing of the flexible strip relative to the floor can be achieved by sliding the strip against the underside of the anodes of the cell or against fixed guides. As a variant, the maintenance of this spacing can be obtained by an appropriate adjustment of its specific weight by incorporating therein, for example, a core made of a dense material, or by electromagnetic attraction adjusted towards the floor, by incorporating therein a core made of a ferromagnetic material, usually an iron powder.
Dans la mise en oeuvre de cette forme d'exécution de l'invention, on introduit la bande à une extérmité de la cellule et on l'y pousse dans le film de mercure, vers l'extrémité opposée de la cellule. Le déplacement de la bande peut être opéré de l'extrémité d'amont vers l'extrémité d'aval de la cellule par rapport au sens d'écoulement du film de mercure ; on préfère toutefois, opérer le déplacement de la bande, de l'extrémité d'aval vers l'extrémité d'amont. Pour faciliter le travail et réduire l'encombrement, on peut avantageusement dérouler la bande dans la cellule depuis un tambour disposé près d'une extrémité de la cellule (par exemple son extrémité d'aval précitée) et, dès que l'extrémité antérieure de la bande a parcouru toute la cellule, l'y déplacer en sens inverse,en l'enroulant à nouveau sur le tambour. Dans ce mode de réalisation du procédé, on peut automatiser les déplacements alternatifs successifs et périodiques de la bande en couplant le tambour à un moteur dont le fonctionnement est assujetti à un dispositif de régulation. Celui-ci peut être programmé de manière à démarrer automatiquement le moteur du tambour à intervalles de temps prêinpusës ; en variante, il peut comprendre un organe de mesure de l'épaisseur de la couche de gros mercure sur la sole et être programmé pour démarrer automatiquement le moteur du tambour dès que l'épaisseur de cette couche, mesurée par l'organe de mesure, excède une valeur critique prédéterminée.In the implementation of this embodiment of the invention, the strip is introduced at one end of the cell and it is pushed there into the mercury film, towards the opposite end of the cell. The strip can be moved from the upstream end to the downstream end of the cell with respect to the direction of flow of the mercury film; however, it is preferred to operate the movement of the strip from the downstream end to the upstream end. To facilitate the work and reduce the bulk, the strip can advantageously be unwound in the cell from a drum placed near one end of the cell (for example its downstream end mentioned above) and, as soon as the anterior end of the strip has traversed the entire cell, moving it in the opposite direction, winding it again on the drum. In this embodiment of the method, it is possible to automate the successive and periodic alternating movements of the strip by coupling the drum to a motor whose operation is subject to a regulating device. This can be programmed to start automatically the drum motor at preset time intervals; as a variant, it may include a member for measuring the thickness of the layer of coarse mercury on the hearth and be programmed to automatically start the drum motor as soon as the thickness of this layer, measured by the measuring member, exceeds a predetermined critical value.
Le procédé selon l'invention trouve une application spécialement intéressante dans le cas de cellules à cathode de mercure approximativement horizontale, habituellement utilisées pour l'électrolyse des solutions aqueuses de chlorure de sodium, et plus spécialement les cellules de ce type équipées d'anodes métalliques.The process according to the invention finds a particularly advantageous application in the case of cells with an approximately horizontal mercury cathode, usually used for the electrolysis of aqueous solutions of sodium chloride, and more especially cells of this type equipped with metal anodes. .
Toutes autres choses restant égales, le procédé selon l'invention diminue la vitesse de formation du gros mercure et, par voie de conséquence, la fréquence des nettoyages de la sole ; il améliore par ailleurs la régularité de l'écoulement du film de mercure, ce qui facilite le contrôle des distances séparant les anodes de la cathode, réduit la fréquence et l'importance des ajustements de la position des anodes vis-à-vis de la cathode et permet de travailler avec des distances anodes-cathode plus faibles.All other things remaining equal, the process according to the invention reduces the rate of formation of coarse mercury and, consequently, the frequency of cleaning of the sole; it also improves the regularity of the flow of the mercury film, which facilitates the control of the distances separating the anodes from the cathode, reduces the frequency and the importance of the adjustments of the position of the anodes with respect to the cathode and allows working with shorter anode-cathode distances.
L'invention concerne dès lors aussi un procédé pour l'électrolyse d'une solution aqueuse d'halogénure de métal alcalin, par exemple de chlorure de sodium, dans une cellule d'électrolyse dont la cathode comprend un film de mercure en écoulement sur une sole métallique, selon lequel on maintient en permanence sur la sole, une pellicule adhérente de gros mercure, d'épaisseur comprise entre 0,04 et 2,5 mm.The invention therefore also relates to a method for the electrolysis of an aqueous solution of an alkali metal halide, for example sodium chloride, in an electrolysis cell the cathode of which comprises a film of mercury flowing over a metallic sole, according to which an adherent film of coarse mercury, between 0.04 and 2.5 mm thick, is permanently maintained on the sole.
Dans le procédé d'électrolyse selon l'invention, il convient généralement que la pellicule de gros mercure recouvre la totalité de la sole. Son épaisseur optimum dépend notamment de l'épaisseur du film de mercure en écoulement. Celui-ci a de préférence une épaisseur comprise entre 2 et 5 mm.In the electrolysis process according to the invention, it is generally advisable for the film of coarse mercury to cover the entire sole. Its optimum thickness depends in particular on the thickness of the flowing mercury film. This preferably has a thickness of between 2 and 5 mm.
L'intérêt de l'invention va apparaître au cours de la description suivante d'essais comparatifs.The advantage of the invention will appear during the following description of comparative tests.
Dans les essais qui vont suivre, on a procédé à l'électrolyse d'une solution aqueuse de chlorure de sodium dans une cellule à cathode mobile de mercure, du type V-200 (Solvay & Cie) décrite dans le traité de J.S.Sconce "Chlorine, its manufacture, properties ans uses", 1962, Reinhold Publishing Corp., New York, pages 187 à 189. La cellule était équipée de 180 anodes formées de lamelles horizontales en titane portant un revêment actif formé d'un mélange d'oxyde de ruthénium et d'oxyde de titane. La distance entre les anodes et la cathode a été fixée à environ 2 mm, le film de mercure en écoulement, formant la cathode, ayant une épaisseur moyenne d'environ 3 mm.In the following tests, an aqueous sodium chloride solution was electrolysed in a cell with a mobile mercury cathode, of the V-200 type (Solvay & Cie) described in JSSconce's treatise "Chlorine, its manufacture, properties ans uses", 1962, Reinhold Publishing Corp., New York, pages 187 to 189. The cell was equipped with 180 anodes formed from horizontal titanium lamellae carrying an active coating formed by '' a mixture of ruthenium oxide and titanium oxide. The distance between the anodes and the cathode was set at about 2 mm, the flowing mercury film, forming the cathode, having an average thickness of about 3 mm.
Pour nettoyer la sole de la cellule, on a d'abord relevé les anodes puis on a introduit, à partir de l'extrémité d'aval de la cellule, une bande flexible en polytétrafluoréthylène contenant une âme en acier et ayant une longueur approximative de 16 m et une épaisseur d'environ 4 mm, et on l'a déplacée dans le film de mercure, vers l'extrémité d'amont de la cellule. Du fait de son poids spécifique et de son âme métallique, la bande est restée immergée d'environ 2 mm dans le film de mercure pendant son déplacement dans la cellule ; elle a de ce fait arraché une couche superficielle des agglomérats de gros mercure présents sur la sole, en y laissant adhérer une pellicule résiduelle de gros mercure d'environ 1 mm d'épaisseur. Après avoir extrait la bande de la cellule, on a descendu les anodes jusqu'à amener leur écartement vis-à-vis du film de mercure à environ 2 mm.To clean the bottom of the cell, the anodes were first raised and then, from the downstream end of the cell, a flexible polytetrafluoroethylene strip containing a steel core and having an approximate length was introduced. 16 m and a thickness of about 4 mm, and it was moved in the mercury film, towards the upstream end of the cell. Due to its specific weight and its metallic core, the strip remained immersed by about 2 mm in the mercury film during its movement in the cell; it therefore tore off a surface layer of the agglomerates of coarse mercury present on the sole, allowing a residual film of coarse mercury about 1 mm thick to adhere thereto. After extracting the strip from the cell, the anodes were lowered until their spacing with respect to the mercury film was approximately 2 mm.
Le fonctionnement de la cellule n'a plus nécessité d'ajustement ultérieur des anodes, durant les 3 jours qui ont suivi.The operation of the cell no longer required subsequent adjustment of the anodes, during the 3 days which followed.
On a procédé comme à l'essai n°1, mais en remplaçant la bande en polytétrafluoréthylëne par un racleur métallique que l'on a utilisé pour éliminer la totalité du gros mercure présent sur la sole de la cellule. Après le raclage, on a descendu les anodes pour amener leur écartement par rapport à la cathode à environ 2 mm, comme à l'essai n° 1. Au cours du fonctionnement ultérieur de la cellule, de nouveaux agglomérats de gros mercure se sont rapidement reformés sur la sole, ce qui a nécessité deux ajustements successifs supplémentaires de la position des anodes, respectivement après 6 heures et après 24 heures de fonctionnement.The procedure was as in test No. 1, but replacing the polytetrafluoroethylene strip with a metal scraper which was used to remove all of the large mercury present on the bottom of the cell. After scraping, the anodes were lowered to bring their distance from the cathode to about 2 mm, as in test No. 1. During the subsequent operation of the cell, new agglomerates of large mercury quickly formed reformed on the sole, which required two additional successive adjustments to the position of the anodes, respectively after 6 hours and after 24 hours of operation.
Claims (10)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| AT84200824T ATE31197T1 (en) | 1983-06-20 | 1984-06-12 | METHOD OF REMOVAL OF MERCURY SLUDGE LAYERS FROM THE BOTTOM OF MERCURY CATHODE ELECTROLYSIS CELLS AND METHOD OF ELECTROLYSIS OF AN AQUEOUS ALKALI METAL HALOGENIDE SOLUTION IN A MERCURY CATHODE CELL. |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| FR8310284 | 1983-06-20 | ||
| FR8310284A FR2547599A1 (en) | 1983-06-20 | 1983-06-20 | PROCESS FOR REMOVING A LARGE MERCURY LAYER FROM THE SOLE OF MERCURY CATHODE ELECTROLYSIS CELLS |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| EP0131977A1 true EP0131977A1 (en) | 1985-01-23 |
| EP0131977B1 EP0131977B1 (en) | 1987-12-02 |
Family
ID=9290032
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| EP84200824A Expired EP0131977B1 (en) | 1983-06-20 | 1984-06-12 | Process for eliminating mercury sludge layers from the bottom of mercury electrolysis cells, and process for elektrolysing an aqueous alcali metal halide solution in a mercury cathode cell |
Country Status (8)
| Country | Link |
|---|---|
| US (1) | US4565613A (en) |
| EP (1) | EP0131977B1 (en) |
| AT (1) | ATE31197T1 (en) |
| BR (1) | BR8402977A (en) |
| DE (1) | DE3467905D1 (en) |
| ES (1) | ES533527A0 (en) |
| FR (1) | FR2547599A1 (en) |
| PT (1) | PT78753A (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| PT2478130E (en) * | 2009-09-16 | 2015-07-02 | Davey Products Pty Ltd | A salt water chlorinator |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2229461A1 (en) * | 1973-05-17 | 1974-12-13 | Ici Ltd | |
| FR2450288A1 (en) * | 1979-02-27 | 1980-09-26 | Montedison Spa | DEVICE FOR CLEANING THE BOTTOM OF A MERCURY CATHODE ELECTROLYTIC CELL OR THE LIKE |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US679476A (en) * | 1900-09-14 | 1901-07-30 | John F Kelly | Electrolyzing and washing apparatus. |
| US1009133A (en) * | 1909-07-22 | 1911-11-21 | Gen Chemical Corp | Electrolytic apparatus. |
| US3321388A (en) * | 1962-08-09 | 1967-05-23 | Asahi Denka Kogyo Kk | Process for coordinated operation of diaphragm and mercury cathode electrolytic cells |
-
1983
- 1983-06-20 FR FR8310284A patent/FR2547599A1/en not_active Withdrawn
-
1984
- 1984-06-12 DE DE8484200824T patent/DE3467905D1/en not_active Expired
- 1984-06-12 EP EP84200824A patent/EP0131977B1/en not_active Expired
- 1984-06-12 AT AT84200824T patent/ATE31197T1/en not_active IP Right Cessation
- 1984-06-18 PT PT78753A patent/PT78753A/en not_active IP Right Cessation
- 1984-06-18 BR BR8402977A patent/BR8402977A/en not_active IP Right Cessation
- 1984-06-19 ES ES533527A patent/ES533527A0/en active Granted
- 1984-06-19 US US06/622,223 patent/US4565613A/en not_active Expired - Fee Related
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2229461A1 (en) * | 1973-05-17 | 1974-12-13 | Ici Ltd | |
| FR2450288A1 (en) * | 1979-02-27 | 1980-09-26 | Montedison Spa | DEVICE FOR CLEANING THE BOTTOM OF A MERCURY CATHODE ELECTROLYTIC CELL OR THE LIKE |
Also Published As
| Publication number | Publication date |
|---|---|
| PT78753A (en) | 1984-07-01 |
| EP0131977B1 (en) | 1987-12-02 |
| US4565613A (en) | 1986-01-21 |
| BR8402977A (en) | 1985-05-28 |
| ES8601334A1 (en) | 1985-10-16 |
| DE3467905D1 (en) | 1988-01-14 |
| FR2547599A1 (en) | 1984-12-21 |
| ES533527A0 (en) | 1985-10-16 |
| ATE31197T1 (en) | 1987-12-15 |
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