EP0368767A1 - Continuous process for manufacturing alkali metal perchlorate - Google Patents

Continuous process for manufacturing alkali metal perchlorate Download PDF

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Publication number
EP0368767A1
EP0368767A1 EP19890420420 EP89420420A EP0368767A1 EP 0368767 A1 EP0368767 A1 EP 0368767A1 EP 19890420420 EP19890420420 EP 19890420420 EP 89420420 A EP89420420 A EP 89420420A EP 0368767 A1 EP0368767 A1 EP 0368767A1
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Prior art keywords
chlorate
electrolysis
perchlorate
sodium
electrolyte
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German (de)
French (fr)
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EP0368767B1 (en
Inventor
Jean-Christophe Millet
Michel Jaccaud
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Arkema France SA
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Elf Atochem SA
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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
    • C25B1/24—Halogens or compounds thereof
    • C25B1/26—Chlorine; Compounds thereof
    • C25B1/265—Chlorates
    • 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
    • C25B1/28—Per-compounds
    • 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
    • C25B15/02—Process control or regulation
    • C25B15/021—Process control or regulation of heating or cooling
    • 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
    • C25B15/08—Supplying or removing reactants or electrolytes; Regeneration of electrolytes
    • 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
    • C25B9/00—Cells or assemblies of cells; Constructional parts of cells; Assemblies of constructional parts, e.g. electrode-diaphragm assemblies; Process-related cell features
    • C25B9/17—Cells comprising dimensionally-stable non-movable electrodes; Assemblies of constructional parts thereof
    • C25B9/19—Cells comprising dimensionally-stable non-movable electrodes; Assemblies of constructional parts thereof with diaphragms
    • C25B9/23—Cells comprising dimensionally-stable non-movable electrodes; Assemblies of constructional parts thereof with diaphragms comprising ion-exchange membranes in or on which electrode material is embedded

Definitions

  • the present invention relates to a continuous process for the manufacture of alkali metal perchlorate by electrolysis of an aqueous chlorate solution of said metal.
  • alkali metal chlorate and the perchlorate of said metal will be designated by chlorate and perchlorate respectively.
  • This consists of electrolyzing the chlorate in a succession of individual electrolytic steps, each step being different from another, dependent on another, and ensuring only a partial electrolysis result compared to the final industrial result. targeted.
  • cascade In a multi-step process, commonly called “cascade", the overall electrolyte balance is disturbed by the electrolyte imbalance of a single step and does not recover by simply decommissioning the failed step.
  • - electrolytic step or electrolysis step the assembly formed by electrolysis and what comes out of it to re-enter it.
  • - electrolyte the liquid to which the electrical conditions used to transform chlorate into perchlorate are applied in electrolysis, and which contains these two compounds in the dissolved state, - perchlorate solution from which it can be isolated directly by crystallization: solution which deposits, by evaporation of water or by cooling, the solid perchlorate in monohydrate, dihydrate or anhydrous form; one can refer on the matter to the work published under the direction of Paul PASCAL, New treaty of Mineral Chemistry, 1966, Volume II, fascicule 1, p.353 and figure 37 which shows the ternary diagram NaClO4-NaClO3-H2O.
  • the present invention consists of a continuous process for the manufacture of perchlorate by electrolysis of an aqueous chlorate solution in a single electrolytic step in which the electrolyte is uniform and has a stationary composition, characterized in that said composition is that of a aqueous solution of perchlorate from which the latter can be isolated directly by crystallization, thus maintained by continuously entering into the electrolysis step, chlorate and water simultaneously, each in an amount equal respectively to the amount of chlorate and to the quantity of water which, as it stands or in combined form, leaves this stage continuously and definitively.
  • - uniform electrolyte an electrolyte which is the same at every point in the space it occupies, as regards in particular its composition, its pH, its temperature, - stationary composition, a stable, constant composition over time.
  • the electrolyte is uniform thanks to its agitation due for example to the evolution of gas in the electrolysis, associated if necessary with recirculation external to the latter, for example using a pump.
  • the electrolyte the composition of which, according to the invention, is the same as that of the aqueous perchlorate solution which leaves the single electrolysis step, contains, in the case of the electrolysis of sodium chlorate into perchlorate sodium, preferably at least 100 g. of chlorate per liter to obtain a FARADAY yield exceeding 90%.
  • the electrolysis is carried out in known equipment, such as for example a non-compartmentalized cell with monopolar electrodes, anode based on platinum, such as for example a sheet of solid platinum or platinum deposited on a conductive substrate, cathode for example of mild steel. or bronze.
  • the electrical conditions adopted are those allowing the transformation of chlorate into perchlorate, for example, for sodium perchlorate, an anodic current density for example of between approximately 10 and 70 A / dm2 and often of the order of 40 A / dm2 .
  • the pH of the electrolyte can be between fairly distant limits, for example between about 6 to 10. It is reached using for example perchloric acid or an alkali metal hydroxide such as hydroxide. sodium in the case of electrolysis of sodium chlorate.
  • the temperature of the electrolyte is generally between approximately 40 ° C and 90 ° C.
  • Heat exchange means which can be both internal and external to the electrolyte make it possible to maintain it at the chosen value.
  • the simultaneous and continuous addition of the chlorate and of the water which enter the single electrolysis stage can be carried out by bringing into this stage an aqueous chlorate solution containing all the chlorate and all the water necessary for the invention.
  • the concentration of this chlorate solution can be very high, for example 900 g. of sodium chlorate per liter, forming the solution at a temperature which is itself high, for example 80 ° C.
  • Relative amounts of chlorate and water such as those indicated for example above can also be achieved by adding chlorate and water separately, the chlorate being used in solid form.
  • the external recirculation current in the single electrolysis step can serve as a vector for the chlorate.
  • Part of it can be provided in the solid state and the additional part provided in the form of an aqueous solution, for example in the form of a solution containing 700 g. of chlorate per liter, formed at 20 ° C.
  • the method according to the invention makes it possible to retain the advantage relating to a reduced consumption of platinum found in patent of the United States of America No. 3475301.
  • perchlorate which constitutes the ultimately targeted production is separated in practically pure solid form directly by crystallization from the aqueous perchlorate solution as it leaves the single electrolysis step according to the invention.
  • the product particularly targeted by the industry is sodium perchlorate monohydrate rather than anhydrous perchlorate or that perchlorate dihydrate whose manufacture, depending on the composition of the electrolyte that is required, is also feasible according to the invention.
  • sodium perchlorate is manufactured by electrolysis of sodium chlorate in equipment essentially comprising an electrolysis cell with external recirculation loop, assembly in which the single electrolysis step is carried out, exchange means calorific, measurement and control of temperature and pH.
  • the electrolysis cell is not compartmentalized and is equipped with monopolar electrodes, platinum anodes and mild steel cathodes, traversed by an electric current such that the anodic current density is equal to 40 A / dm2.
  • the gas evolution in the cell and the sufficiently significant recirculation ensure the uniformity of the electrolyte in said cell.
  • the electrolyte contains, for 100 g. of water, 26 g. sodium chlorate, 180 g. sodium perchlorate and 0.3 g. sodium dichromate.
  • the composition of the electrolyte thus fixed is kept stable over time by continuously entering the single electrolysis step 96 cm3 / h.dm2 anodic of a sodium chlorate solution at 80 ° C containing, per liter. , 900 g. sodium chlorate, 1.5 g. sodium dichromate and the amount of perchloric acid necessary for the pH of the electrolyte in the electrolysis cell, temperature is 65 ° C, equal to 6.5. 85 cm3 / h.dm2 anodic of an aqueous solution which, according to the invention, has the composition of the electrolyte, continuously leaves the single electrolysis stage in order to isolate therefrom directly by crystallization the sodium perchlorate monohydrate which represents the target production.
  • Example 2 This example is carried out in the equipment and according to the operating process of Example 1.
  • the electrolysis is carried out in particular at the same temperature and at the same pH as in Example 1.
  • the electrolyte this time contains, for 100 g. of water 36 g. sodium chlorate, 220 g. sodium perchlorate and 0.3 g. sodium dichromate.
  • This composition is kept stable over time by continuously entering into the single electrolysis stage 46 g / h.dm2 anodic of solid sodium chlorate via the recirculation current, and 84 cm3 / h.dm2 anodic of an aqueous solution at 20 ° C containing, per liter, 500 g. sodium chlorate, 1.5 g.
  • Example is also carried out in the equipment and according to the operating process of Example 1.
  • the electrolysis is carried out at the same temperature and at the same pH as in Example 1.
  • the electrolyte contains, per 100 g. of water, 30 g. sodium chlorate and 290 g. sodium perchlorate next to 0.3 g. sodium dichromate.
  • the electrolyte is maintained at this composition stable over time by continuously entering the state.
  • the FARADAY yield expressed as the ratio of the amount of electricity actually used for the conversion of chlorate to perchlorate, in a given time, to the total amount of electricity consumed at the same time, is greater than 90% for the three examples above. It is more than 93%, even in the absence of sodium dichromate by repeating Example 1 with an electrolysis temperature equal to 55 ° C instead of 65 ° C.

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Abstract

Continuous manufacture of alkali metal perchlorate by electrolysis of an aqueous solution of chlorate of the said metal in a single electrolytic stage with a uniform electrolyte of stationary composition, characterised in that the said composition is that of an aqueous solution of perchlorate from which the latter is capable of being isolated directly by crystallisation, which is maintained thus by continuously introducing chlorate and water simultaneously into the electrolysis stage, each being in a quantity equal to that of the chlorate and of the water respectively, which, in this form or in combined form, leave the said stage continuously and definitively.

Description

La présente invention concerne un procédé continu de fabrication de perchlorate de métal alcalin par électroly­se d'une solution aqueuse de chlorate dudit métal.The present invention relates to a continuous process for the manufacture of alkali metal perchlorate by electrolysis of an aqueous chlorate solution of said metal.

Dans tout ce qui suit on désignera, sauf précision ou évidence, le chlorate de métal alcalin et le perchlorate dudit métal par chlorate et perchlorate respectivement.In what follows, unless indicated or indicated, the alkali metal chlorate and the perchlorate of said metal will be designated by chlorate and perchlorate respectively.

L'avantage à opérer en continu est évoqué par exemple dans le brevet français n°1402590. Ce brevet et, par exemple, les brevets des Etats Unis d'Amérique n°3518173, n°3518180, n°3475301 et le brevet anglais n°125608, illustrent la technique connue.The advantage of operating continuously is mentioned, for example, in French patent No. 1402590. This patent and, for example, United States patents No. 3518173, No. 3518180, No. 3475301 and English patent No. 125608, illustrate the known technique.

Celle-ci consiste à électrolyser le chlorate dans une succession d'étapes électrolytiques individuelles, chaque étape étant différente d'une autre, tributaire d'une autre, et n'assurant qu'un résultat d'électrolyse partiel par rapport au résultat industriel final visé.This consists of electrolyzing the chlorate in a succession of individual electrolytic steps, each step being different from another, dependent on another, and ensuring only a partial electrolysis result compared to the final industrial result. targeted.

C'est ainsi en effet qu'est produite jusqu'à aujourd'hui une solution aqueuse de perchlorate sortant de l'électrolyse du chlorate, qui soit telle que le perchlorate puisse en être séparé directement par cristallisation, par exemple par refroidissement ou par évaporation d'eau.This is how an aqueous solution of perchlorate leaving the chlorate electrolysis is produced until today, which is such that the perchlorate can be separated therefrom directly by crystallization, for example by cooling or by evaporation. of water.

En effet il était connu qu'une électrolyse du chlorate en une seule étape n'aboutissait pas à une telle solution dans les conditions pratiques de réalisation de l'étape unique décrites par exemple dans le brevet des Etats Unis d'Amérique n°2512973.Indeed, it was known that an electrolysis of chlorate in a single step did not lead to such a solution under the practical conditions for carrying out the single step described for example in United States patent No. 2512973.

Opérer successivement dans un grand nombre d'étapes individuelles est par contre recommandé, par exemple dans le brevet des Etats Unis d'Amérique n°3475301 déjà cité.Operating successively in a large number of individual steps is however recommended, for example in the patent of the United States of America No. 3475301 already cited.

Dans un procédé en plusieurs étapes, dit communé­ment "en cascade", l'équilibre électrolytique global est perturbé par le déséquilibre électrolytique d'une seule étape et ne se rétablit pas par simple mise hors service de l'étape défaillante.In a multi-step process, commonly called "cascade", the overall electrolyte balance is disturbed by the electrolyte imbalance of a single step and does not recover by simply decommissioning the failed step.

Il a été maintenant trouvé un procédé continu en une seule étape électrolytique qui ne présente pas l'inconvé­nient ci-dessus et qui délivre une solution de perchlorate conduisant directement par cristallisation au perchlorate solide de degré de pureté élevé.A continuous process has now been found in a single electrolytic step which does not have the above drawback and which delivers a perchlorate solution leading directly by crystallization to solid perchlorate of high degree of purity.

Dans tout ce qui précède et dans tout ce qui suit, on désigne par :
- étape électrolytique ou étape d'électrolyse, l'ensemble formé de l'électrolyse et de ce qui en sort pour y entrer à nouveau.
- électrolyte, le liquide auquel sont appliquées dans l'électrolyse les conditions électriques permettant de transformer du chlorate en perchlorate, et qui contient ces deux composés à l'état dissous,
- solution de perchlorate de laquelle celui-ci est isolable directement par cristallisation : solution qui dépo­se, par évaporation d'eau ou par refroidissement, le perchlo­rate solide sous forme monohydrate, dihydrate ou anhydre ; on peut se reporter en la matière à l'ouvrage publié sous la direction de Paul PASCAL, Nouveau traité de Chimie Minérale, 1966, Tome II, fascicule 1, p.353 et figure 37 qui montre le diagramme ternaire NaClO₄-NaClO₃-H₂O.In all of the above and in all that follows, we mean by:
- electrolytic step or electrolysis step, the assembly formed by electrolysis and what comes out of it to re-enter it.
- electrolyte, the liquid to which the electrical conditions used to transform chlorate into perchlorate are applied in electrolysis, and which contains these two compounds in the dissolved state,
- perchlorate solution from which it can be isolated directly by crystallization: solution which deposits, by evaporation of water or by cooling, the solid perchlorate in monohydrate, dihydrate or anhydrous form; one can refer on the matter to the work published under the direction of Paul PASCAL, New treaty of Mineral Chemistry, 1966, Volume II, fascicule 1, p.353 and figure 37 which shows the ternary diagram NaClO₄-NaClO₃-H₂O.

La présente invention consiste en un procédé conti­nu de fabrication de perchlorate par électrolyse d'une solu­tion aqueuse de chlorate en une seule étape électrolytique dans laquelle l'électrolyte est uniforme et a une composition stationnaire, caractérisé en ce que ladite composition est celle d'une solution aqueuse de perchlorate de laquelle celui-­ci est isolable directement par cristallisation, maintenue ainsi en faisant entrer en continu dans l'étape d'électroly­se, du chlorate et de l'eau simultanément, chacun en quantité égale respectivement à la quantité de chlorate et à la quantité d'eau qui, en l'état ou sous forme combinée, sortent en continu et définitivement de ladite étape.The present invention consists of a continuous process for the manufacture of perchlorate by electrolysis of an aqueous chlorate solution in a single electrolytic step in which the electrolyte is uniform and has a stationary composition, characterized in that said composition is that of a aqueous solution of perchlorate from which the latter can be isolated directly by crystallization, thus maintained by continuously entering into the electrolysis step, chlorate and water simultaneously, each in an amount equal respectively to the amount of chlorate and to the quantity of water which, as it stands or in combined form, leaves this stage continuously and definitively.

Dans la définition ainsi donnée de l'invention, comme dans tout ce qui suit, on entend par :
- électrolyte uniforme, un électrolyte qui est le même en tout point de l'espace qu'il occupe, pour ce qui con­cerne en particulier sa composition, son pH, sa température,
- composition stationnaire, une composition stable, constante, dans le temps.In the definition thus given of the invention, as in all that follows, by:
- uniform electrolyte, an electrolyte which is the same at every point in the space it occupies, as regards in particular its composition, its pH, its temperature,
- stationary composition, a stable, constant composition over time.

L'électrolyte est uniforme grâce à son agitation due par exemple au dégagement gazeux dans l'électrolyse, associé le cas échéant à une recirculation externe à celle-ci par exemple à l'aide d'une pompe.The electrolyte is uniform thanks to its agitation due for example to the evolution of gas in the electrolysis, associated if necessary with recirculation external to the latter, for example using a pump.

L'électrolyte, dont la composition, selon l'inven­tion, est la même que celle de la solution aqueuse de perchlo­rate qui sort de l'étape unique d'électrolyse, renferme, dans le cas de l'électrolyse du chlorate de sodium en perchlorate de sodium, de préférence au moins 100 g. de chlorate par litre pour obtenir un rendement FARADAY dépassant 90 %.The electrolyte, the composition of which, according to the invention, is the same as that of the aqueous perchlorate solution which leaves the single electrolysis step, contains, in the case of the electrolysis of sodium chlorate into perchlorate sodium, preferably at least 100 g. of chlorate per liter to obtain a FARADAY yield exceeding 90%.

Le maintien de la concentration de l'électrolyte en chlorate et en perchlorate, respectivement, à une valeur constante dans le temps, permet d'éviter une augmentation de la tension aux bornes des électrodes.Maintaining the electrolyte concentration of chlorate and perchlorate, respectively, at a constant value over time, makes it possible to avoid an increase in the voltage across the electrodes.

La consommation énergétique par tonne de perchlora­te finalement produit est inférieure à celle concédée en opérant selon les procédés connus.The energy consumption per ton of perchlorate ultimately produced is lower than that conceded by operating according to known methods.

L'électrolyse est réalisée dans un équipement connu, comme par exemple une cellule non compartimentée à électrodes monopolaires, anode à base de platine, comme par exemple une feuille de platine massif ou du platine déposé sur un substrat conducteur, cathode par exemple en acier doux ou en bronze.The electrolysis is carried out in known equipment, such as for example a non-compartmentalized cell with monopolar electrodes, anode based on platinum, such as for example a sheet of solid platinum or platinum deposited on a conductive substrate, cathode for example of mild steel. or bronze.

Les conditions électriques adoptées sont celles permettant la transformation du chlorate en perchlorate, par exemple, pour le perchlorate de sodium, une densité de courant anodique comprise par exemple entre environ 10 et 70 A/dm² et souvent de l'ordre de 40 A/dm².The electrical conditions adopted are those allowing the transformation of chlorate into perchlorate, for example, for sodium perchlorate, an anodic current density for example of between approximately 10 and 70 A / dm² and often of the order of 40 A / dm² .

Le pH de l'électrolyte peut être compris entre des limites assez éloignées, par exemple entre environ 6 à 10. Il est atteint à l'aide par exemple d'acide perchlorique ou d'un hydroxyde de métal alcalin tel que l'hydroxyde de sodium dans le cas de l'électrolyse du chlorate de sodium.The pH of the electrolyte can be between fairly distant limits, for example between about 6 to 10. It is reached using for example perchloric acid or an alkali metal hydroxide such as hydroxide. sodium in the case of electrolysis of sodium chlorate.

L'eau qui entre dans l'étape unique d'électrolyse avec par exemple les composés ci-dessus ou avec d'autres ingrédients possibles de l'électrolyte tel que le bichromate de sodium, utilisé le plus souvent à raison d'environ 1 g. à 5 g. par litre d'électrolyte dans le cas de l'électrolyse du chlorate de sodium, doit être prise en compte dans la condui­te du procédé selon l'invention.Water which enters the single electrolysis step with, for example, the above compounds or with other possible ingredients of the electrolyte such as sodium dichromate, used most often at a rate of approximately 1 g . at 5 g. per liter of electrolyte in the case of the electrolysis of sodium chlorate, must be taken into account in the conduct of the process according to the invention.

Il en est de même le cas échéant de l'eau apportée à l'étape unique d'électrolyse qui a pour origine la cristal­lisation de la solution aqueuse telle qu'elle sort de ladite étape : condensat d'eau évaporée de ladite solution, eaux-­mères et eau de lavage du perchlorate solide produit.The same applies, where appropriate, to the water supplied to the single electrolysis stage which originates from the crystallization of the aqueous solution as it leaves said stage: condensate of water evaporated from said solution, water -mothers and washing water of the solid perchlorate produced.

La température de l'électrolyte est généralement comprise entre environ 40°C et 90°C. Des moyens d'échange ca­lorifique qui peuvent être aussi bien internes qu'externes à l'électrolyte permettent de la maintenir à la valeur choisie.The temperature of the electrolyte is generally between approximately 40 ° C and 90 ° C. Heat exchange means which can be both internal and external to the electrolyte make it possible to maintain it at the chosen value.

L'addition simultanée et continue du chlorate et de l'eau qui entrent dans l'étape unique d'électrolyse est réalisable en faisant entrer dans cette étape une solution aqueuse de chlorate contenant tout le chlorate et toute l'eau nécessaires à l'invention. La concentration de cette solution en chlorate peut être très élevée, par exemple 900 g. de chlorate de sodium par litre, en formant la solution à une température elle-même élevée, par exemple 80°C.The simultaneous and continuous addition of the chlorate and of the water which enter the single electrolysis stage can be carried out by bringing into this stage an aqueous chlorate solution containing all the chlorate and all the water necessary for the invention. . The concentration of this chlorate solution can be very high, for example 900 g. of sodium chlorate per liter, forming the solution at a temperature which is itself high, for example 80 ° C.

Des quantités relatives de chlorate et d'eau telles que celles indiquées par exemple ci-dessus peuvent encore être atteintes en additionnant séparément le chlorate et l'eau, le chlorate étant mis en oeuvre sous forme solide. Dans ce cas, le courant de recirculation externe dans l'étape unique d'électrolyse peut servir de vecteur au chlorate.Relative amounts of chlorate and water such as those indicated for example above can also be achieved by adding chlorate and water separately, the chlorate being used in solid form. In this case, the external recirculation current in the single electrolysis step can serve as a vector for the chlorate.

Une partie de celui-ci peut être apportée à l'état solide et la partie complémentaire apportée sous forme de solution aqueuse, par exemple sous forme d'une solution contenant 700 g. de chlorate par litre, formée à 20°C.Part of it can be provided in the solid state and the additional part provided in the form of an aqueous solution, for example in the form of a solution containing 700 g. of chlorate per liter, formed at 20 ° C.

Le procédé selon l'invention permet de conserver l'avantage relatif à une consommation réduite de platine constaté dans le brevet des Etats Unis d'Amérique n°3475301.The method according to the invention makes it possible to retain the advantage relating to a reduced consumption of platinum found in patent of the United States of America No. 3475301.

Le perchlorate qui constitue la production finale­ment visée est séparé sous forme solide pratiquement pure directement par cristallisation de la solution aqueuse de per­chlorate telle qu'elle sort de l'étape unique d'électrolyse selon l'invention. Dans le cas de la fabrication de perchlora­ te de sodium, le produit particulièrement visé par l'indus­trie est le perchlorate de sodium monohydrate plutôt que le perchlorate anhydre ou que le perchlorate dihydrate dont la fabrication, selon la composition de l'électrolyte que l'on s'impose, est aussi réalisable selon l'invention.The perchlorate which constitutes the ultimately targeted production is separated in practically pure solid form directly by crystallization from the aqueous perchlorate solution as it leaves the single electrolysis step according to the invention. In the case of the manufacture of perchlora sodium, the product particularly targeted by the industry is sodium perchlorate monohydrate rather than anhydrous perchlorate or that perchlorate dihydrate whose manufacture, depending on the composition of the electrolyte that is required, is also feasible according to the invention.

Les exemples suivants, donnés à titre indicatif mais non limitatif, illustrent l'invention.The following examples, given as an indication but not limiting, illustrate the invention.

Exemple 1 :Example 1:

Dans cet exemple, du perchlorate de sodium est fabriqué par électrolyse de chlorate de sodium dans un équi­pement comportant essentiellement une cellule d'électrolyse avec boucle de recirculation externe, ensemble dans lequel est réalisée l'étape unique d'électrolyse, des moyens d'échange calorifique, de mesure et de contrôle de la tempé­rature et du pH. La cellule d'électrolyse est non comparti­mentée et est équipée d'électrodes monopolaires, anodes en platine et cathodes en acier doux, parcourues par un courant électrique tel que la densité de courant anodique soit égale à 40 A/dm². Le dégagement gazeux dans la cellule et la recirculation suffisamment importante assurent l'uniformité de l'électrolyte dans ladite cellule.In this example, sodium perchlorate is manufactured by electrolysis of sodium chlorate in equipment essentially comprising an electrolysis cell with external recirculation loop, assembly in which the single electrolysis step is carried out, exchange means calorific, measurement and control of temperature and pH. The electrolysis cell is not compartmentalized and is equipped with monopolar electrodes, platinum anodes and mild steel cathodes, traversed by an electric current such that the anodic current density is equal to 40 A / dm². The gas evolution in the cell and the sufficiently significant recirculation ensure the uniformity of the electrolyte in said cell.

On forme initialement dans cette dernière, soit directement à partir de ses constituants, soit déjà par électrolyse progressive de chlorate de sodium, un électrolyte qui est une solution aqueuse de chlorate de sodium et de perchlorate de sodium en présence d'une petite quantité de bichromate de sodium, de laquelle le perchlorate de sodium est isolable directement par cristallisation.It is initially formed in the latter, either directly from its constituents, or already by progressive electrolysis of sodium chlorate, an electrolyte which is an aqueous solution of sodium chlorate and sodium perchlorate in the presence of a small amount of dichromate. sodium, from which sodium perchlorate can be isolated directly by crystallization.

Dans le cas présent l'électrolyte contient, pour 100 g. d'eau, 26 g. de chlorate de sodium, 180 g. de perchlo­rate de sodium et 0,3 g. de bichromate de sodium.In the present case the electrolyte contains, for 100 g. of water, 26 g. sodium chlorate, 180 g. sodium perchlorate and 0.3 g. sodium dichromate.

La composition de l'électrolyte ainsi fixée est maintenue stable dans le temps en faisant entrer en continu dans l'étape unique d'électrolyse 96 cm³/h.dm² anodique d'une solution de chlorate de sodium à 80°C contenant, par litre, 900 g. de chlorate de sodium, 1,5 g. de bichromate de sodium et la quantité d'acide perchlorique nécessaire pour que, dans la cellule d'électrolyse, le pH de l'électrolyte dont la température est de 65°C, soit égal à 6,5. 85 cm³/h.dm² anodique d'une solution aqueuse qui, selon l'invention, a la composition de l'électrolyte, sort en continu de l'étape unique d'électrolyse pour en isoler directement par cristal­lisation le perchlorate de sodium monohydrate qui représente la production visée.The composition of the electrolyte thus fixed is kept stable over time by continuously entering the single electrolysis step 96 cm³ / h.dm² anodic of a sodium chlorate solution at 80 ° C containing, per liter. , 900 g. sodium chlorate, 1.5 g. sodium dichromate and the amount of perchloric acid necessary for the pH of the electrolyte in the electrolysis cell, temperature is 65 ° C, equal to 6.5. 85 cm³ / h.dm² anodic of an aqueous solution which, according to the invention, has the composition of the electrolyte, continuously leaves the single electrolysis stage in order to isolate therefrom directly by crystallization the sodium perchlorate monohydrate which represents the target production.

Exemple 2 :Example 2:

Cet exemple est réalisé dans l'équipement et selon le processus opératoire de l'exemple 1. L'électrolyse est réalisée en particulier à la même température et au même pH que dans l'exemple 1. L'électrolyte contient cette fois, pour 100 g. d'eau 36 g. de chlorate de sodium, 220 g. de perchlora­te de sodium et 0,3 g. de bichromate de sodium. Cette composi­tion est maintenue stable dans le temps en faisant entrer en continu dans l'étape unique d'électrolyse 46 g/h.dm² anodique de chlorate de sodium solide par l'intermédiaire du courant de recirculation, et 84 cm³/h.dm² anodique d'une solution aqueuse à 20°C contenant, par litre, 500 g. de chlorate de sodium, 1,5 g. de bichromate de sodium et la quantité d'acide perchlorique nécessaire pour atteindre dans l'électrolyte un pH de 6,5. 76 cm³/h.dm² anodique de solution aqueuse de perchlorate sort de l'étape unique d'électrolyse d'où le perchlorate de sodium monohydrate peut être recueilli directement par cristallisation.This example is carried out in the equipment and according to the operating process of Example 1. The electrolysis is carried out in particular at the same temperature and at the same pH as in Example 1. The electrolyte this time contains, for 100 g. of water 36 g. sodium chlorate, 220 g. sodium perchlorate and 0.3 g. sodium dichromate. This composition is kept stable over time by continuously entering into the single electrolysis stage 46 g / h.dm² anodic of solid sodium chlorate via the recirculation current, and 84 cm³ / h.dm² anodic of an aqueous solution at 20 ° C containing, per liter, 500 g. sodium chlorate, 1.5 g. sodium dichromate and the amount of perchloric acid necessary to reach a pH of 6.5 in the electrolyte. 76 cm³ / h.dm² anodic aqueous perchlorate solution leaves the single electrolysis stage from which sodium perchlorate monohydrate can be collected directly by crystallization.

Exemple 3 :Example 3:

Cet exemple est réalisé encore dans l'équipement et selon le processus opératoire de l'exemple 1. L'électrolyse est conduite à la même température et au même pH que dans l'exemple 1.This example is also carried out in the equipment and according to the operating process of Example 1. The electrolysis is carried out at the same temperature and at the same pH as in Example 1.

L'électrolyte dont la composition est celle de la solution aqueuse de perchlorate de sodium d'où le perchlorate de sodium fabriqué pourra être isolé directement par cristal­lisation, contient, pour 100 g. d'eau, 30 g. de chlorate de sodium et 290 g. de perchlorate de sodium à côté de 0,3 g. de bichromate de sodium.The electrolyte, the composition of which is that of the aqueous sodium perchlorate solution from which the sodium perchlorate produced can be isolated directly by crystallization, contains, per 100 g. of water, 30 g. sodium chlorate and 290 g. sodium perchlorate next to 0.3 g. sodium dichromate.

L'électrolyte est maintenu à cette composition stable dans le temps en faisant entrer en continu dans l'éta­ pe unique d'électrolyse 45 g/h.dm² anodique de chlorate de sodium solide par l'intermédiaire du courant de recircula­tion et 74 cm³/h.dm² anodique d'une solution aqueuse de chlorate de sodium de l'exemple 2, tandis que sort de l'étape unique d'électrolyse 66 cm³/h.dm² anodique de solution aqueuse de même composition que l'électrolyte et d'où le perchlorate fabriqué peut être isolé directement sous forme anhydre par cristallisation.The electrolyte is maintained at this composition stable over time by continuously entering the state. single electrolysis pe 45 g / h.dm² anodic of solid sodium chlorate via the recirculation current and 74 cm³ / h.dm² anodic of an aqueous solution of sodium chlorate of Example 2, while leaves the single electrolysis stage 66 cm³ / h.dm² anodic aqueous solution of the same composition as the electrolyte and from which the perchlorate produced can be isolated directly in anhydrous form by crystallization.

Le rendement FARADAY, exprimé comme étant le rapport de la quantité d'électricité effectivement utilisée pour la conversion du chlorate en perchlorate, en un temps donné, à la quantité totale d'électricité consommée dans le même temps, est supérieur à 90 % pour les trois exemples ci-­dessus. Il est de plus de 93 %, même en l'absence de bichromate de sodium en répétant l'exemple 1 avec une température d'électrolyse égale à 55°C au lieu de 65°C.The FARADAY yield, expressed as the ratio of the amount of electricity actually used for the conversion of chlorate to perchlorate, in a given time, to the total amount of electricity consumed at the same time, is greater than 90% for the three examples above. It is more than 93%, even in the absence of sodium dichromate by repeating Example 1 with an electrolysis temperature equal to 55 ° C instead of 65 ° C.

Claims (8)

1. Procédé continu de fabrication de perchlorate de métal alcain par électrolyse d'une solution aqueuse de chlora­te dudit métal en une seule étape électrolytique dans laquel­le l'électrolyte est uniforme et a une composition station­naire, caractérisé en ce que ladite composition est celle d'une solution aqueuse de perchlorate de laquelle celui-ci est isolable directement par cristallisation, maintenue ainsi en faisant entrer en continu dans l'étape d'électrolyse, du chlorate et de l'eau simultanément, chacun en quantité égale respectivement à la quantité de chlorate et à la quantité d'eau qui, en l'état ou sous forme combinée, sortent en continu et définitivement de ladite étape.1. Continuous process for the manufacture of alkali metal perchlorate by electrolysis of an aqueous chlorate solution of said metal in a single electrolytic step in which the electrolyte is uniform and has a stationary composition, characterized in that said composition is that of an aqueous solution of perchlorate from which the latter can be isolated directly by crystallization, thus maintained by continuously entering into the electrolysis step, chlorate and water simultaneously, each in an amount equal respectively to the amount of chlorate and to the quantity of water which, in the state or in combined form, leaves continuously and permanently from said stage. 2. Procédé selon la revendication 1, caractérisé en ce que tout le chlorate et toute l'eau qui entrent dans l'étape unique d'électrolyse sont contenus dans une solution aqueuse de chlorate.2. Method according to claim 1, characterized in that all the chlorate and all the water which enter the single electrolysis stage are contained in an aqueous solution of chlorate. 3. Procédé selon la revendication 1, caractérisé en ce que tout le chlorate entre sous forme solide dans l'étape unique d'électrolyse.3. Method according to claim 1, characterized in that all the chlorate enters in solid form in the single electrolysis step. 4. Procédé selon la revendication 1, caractérisé en ce qu'une partie du chlorate entre sous forme solide dans l'étape unique d'électrolyse, le reste du chlorate entrant sous forme de solution aqueuse dans ladite étape.4. Method according to claim 1, characterized in that part of the chlorate enters in solid form in the single electrolysis step, the rest of the chlorate entering in the form of an aqueous solution in said step. 5. Procédé selon l'une des revendications 1 à 4, caractérisé en ce que l'électrolyte est maintenu tel qu'il contienne, par litre, au moins 100 g. de chlorate de sodium dans le cas de l'électrolyse du chlorate de sodium en perchlorate de sodium.5. Method according to one of claims 1 to 4, characterized in that the electrolyte is maintained such that it contains, per liter, at least 100 g. of sodium chlorate in the case of the electrolysis of sodium chlorate to sodium perchlorate. 6. Procédé selon l'une des revendications 1 à 5, caractérisé en ce que l'électrolyse est réalisée dans une cellule d'électrolyse non compartimentée équipée d'électrodes monopolaires.6. Method according to one of claims 1 to 5, characterized in that the electrolysis is carried out in a non-compartmentalized electrolysis cell equipped with monopolar electrodes. 7. Procédé selon la revendication 6, caractérisé en ce que le matériau anodique est à base de platine, le matériau cathodique est l'acier doux ou le bronze.7. Method according to claim 6, characterized in that the anode material is based on platinum, the cathode material is mild steel or bronze. 8. Procédé selon l'une des revendications 6 ou 7, caractérisé en ce que, dans le cas de l'électrolyse du chlorate de sodium en perchlorate de sodium, l'électrolyse est réalisée avec une densité de courant anodique égale à une valeur comprise entre 10 et 70 A/dm², à une température égale à une valeur comprise entre 40°C et 90°C et à un pH égal à une valeur comprise entre 6 et 10.8. Method according to one of claims 6 or 7, characterized in that, in the case of the electrolysis of sodium chlorate to sodium perchlorate, the electrolysis is carried out with an anodic current density equal to a value included between 10 and 70 A / dm², at a temperature equal to a value between 40 ° C and 90 ° C and at a pH equal to a value between 6 and 10.
EP89420420A 1988-11-09 1989-10-26 Continuous process for manufacturing alkali metal perchlorate Expired - Lifetime EP0368767B1 (en)

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FR8815137A FR2638766B1 (en) 1988-11-09 1988-11-09 CONTINUOUS PROCESS FOR THE MANUFACTURE OF ALKALINE METAL PERCHLORATE

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FR2810308A1 (en) * 2000-06-20 2001-12-21 Atofina Preparation of anhydrous sodium perchlorate crystals derived form electrolysis of aqueous sodium chlorate by vacuum evaporation

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FR2655061B1 (en) * 1989-11-29 1993-12-10 Atochem MANUFACTURE OF ALKALINE METAL CHLORATE OR PERCHLORATE.
US5131989A (en) * 1991-05-17 1992-07-21 Olin Corporation Process for producing perchloric acid and ammonium perchlorate
AU3227093A (en) * 1991-12-12 1993-07-19 Olin Corporation Process for producing lithium perchlorate
US20030153661A1 (en) * 2002-01-04 2003-08-14 Crompton Corporation Stability improvement of aluminum hydroxide in PVC compound
JP4778320B2 (en) * 2006-01-24 2011-09-21 ペルメレック電極株式会社 Electrosynthesis of perchloric acid compounds
JP4849420B2 (en) * 2007-06-20 2012-01-11 奥野製薬工業株式会社 Method for electrolytic treatment of etching solution
KR101386706B1 (en) * 2009-03-26 2014-04-18 가부시키가이샤 아이에이치아이 Manufacturing method and manufacturing device for perchlorate
JP5392158B2 (en) * 2010-03-19 2014-01-22 株式会社Ｉｈｉ Perchlorate production apparatus and production method
KR101229007B1 (en) * 2010-09-03 2013-02-01 한국표준과학연구원 Preparation method of perchlorate
CN103409770B (en) * 2013-08-01 2016-06-01 株洲市强盛电极有限公司 A kind of perchlorate electrolyzer and electrolysis process
US10318904B2 (en) 2016-05-06 2019-06-11 General Electric Company Computing system to control the use of physical state attainment of assets to meet temporal performance criteria
US10570013B2 (en) * 2016-10-25 2020-02-25 Malvi Technologies, Llc Methods to make ammonium perchlorate

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FR2810308A1 (en) * 2000-06-20 2001-12-21 Atofina Preparation of anhydrous sodium perchlorate crystals derived form electrolysis of aqueous sodium chlorate by vacuum evaporation
WO2001098203A1 (en) * 2000-06-20 2001-12-27 Atofina Method for making anhydrous sodium perchlorate

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