EP0488862A1 - Prevention against acid mist in metal electrowinning - Google Patents
Prevention against acid mist in metal electrowinning Download PDFInfo
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- EP0488862A1 EP0488862A1 EP91403156A EP91403156A EP0488862A1 EP 0488862 A1 EP0488862 A1 EP 0488862A1 EP 91403156 A EP91403156 A EP 91403156A EP 91403156 A EP91403156 A EP 91403156A EP 0488862 A1 EP0488862 A1 EP 0488862A1
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- polyelectrolyte
- styrene
- foam
- metal
- sulfonic acid
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- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25C—PROCESSES FOR THE ELECTROLYTIC PRODUCTION, RECOVERY OR REFINING OF METALS; APPARATUS THEREFOR
- C25C1/00—Electrolytic production, recovery or refining of metals by electrolysis of solutions
- C25C1/16—Electrolytic production, recovery or refining of metals by electrolysis of solutions of zinc, cadmium or mercury
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- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25C—PROCESSES FOR THE ELECTROLYTIC PRODUCTION, RECOVERY OR REFINING OF METALS; APPARATUS THEREFOR
- C25C1/00—Electrolytic production, recovery or refining of metals by electrolysis of solutions
Definitions
- the present invention relates to the problems associated with the formation of acid mist during the electrolytic recovery of metals.
- electrolysis is used both for electroplating and for the recovery of metals.
- the goal is to deposit a smooth layer of metal on the substrate; this is generally achieved by using an alkaline electrolytic bath with relatively low current densities, so as to deposit a layer of metal slowly and regularly.
- strongly acidic conditions are applied with relatively high current densities, since the aim is to cause the deposition of the regenerated metal on the electrode in such a way that it can be easily detached by scraping.
- a main problem associated with electrolytic recovery processes is the formation of an acid mist which results from the evolution of gases, mainly hydrogen, during the electrolysis process.
- This acid mist is a health hazard and attempts have been made to remove it by various methods. These were both mechanical and chemical. Chemical treatments usually work by creating a surface layer of foam on the electrolyte. This surface layer of foam covers the fog and thus reduces the risks.
- the foam layer should be about 2 cm thick. In practice, it generally proves necessary to use an antifoaming agent in conjunction with these surfactants in order to achieve the appropriate foam height. In addition, it has been found that many of these surfactants are attacked by the strongly acidic and oxidative nature of the electrolyte while others affect the efficiency of the electrolysis cell and the quality of the electrolyte. metallic deposit.
- the foaming agent does not interfere with the "edge" of the metal deposit, since this edge is necessary if the deposit must be effectively detached from the electrode by mechanical scissors.
- the foaming agent it is desirable for the foaming agent to be effective at temperatures of up to approximately 50 ° C., since it is difficult to keep the cells very below this temperature, especially in hot weather. It is desirable that the atmospheric concentration of sulfuric acid (the acid normally used) is not more than 1 mg.m ⁇ 3.
- a method for the electrolytic recovery of a metal which consists in electrolyzing an acidic solution of the metal, the solution containing, in the dissolved state, an anionic or cationic polyelectrolyte which is ionized under the conditions of 'electrolysis employed and whose molecule has a hydrophobic fragment so that the surface tension of the surface of the bath is sufficiently reduced to produce a foam.
- the polyelectrolyte also has a hydrophilic fragment which is not ionized under the conditions of electrolysis; it is believed that this hydrophilic moiety can improve the solubility of the polyelectrolyte.
- the present invention is applicable to the electrolytic recovery of metals which can be recovered under acidic conditions, typically using sulfuric acid.
- metals include cobalt, nickel, chromium, thallium and indium and, in particular, zinc, cadmium, copper and manganese, for example.
- the following description refers in particular to zinc, but those skilled in the art will realize that by making routine modifications the invention can be applied to other metals which can be recovered by carrying out acid electrolysis.
- the polyelectrolytes used in the present invention are preferably those in which the iosinating groups are not part of the polymer backbone but are presented as side groups.
- Particularly preferred polyelectrolytes are polymers containing sulfonate side groups, generally derived from styrene sulfonic acid or a salt thereof as a monomer. Note however that the functional group can be anionic or cationic.
- Other monomers which can be used include vinylsulfonic acid, vinylphosphonic acid, 2-acrylamidomethylpropane-sulfonic acid and 2- and 4-vinylpyridines, and their salts, generally the sodium salt.
- the molecular weight of the polyelectrolyte is not particularly critical; values from 104 to 107, especially from 105 to 106, are generally appropriate.
- the polyelectrolyte used in the present invention can be a homopolymer or a copolymer. It will be noted that the balance between the effect of lowering the surface tension and the effect of increasing viscosity can be modified by choosing the relative proportions of the hydrophobic unit and any hydrophilic unit which may be included.
- Suitable hydrophobic monomers which can be used to obtain the copolymers include ethylenically unsaturated hydrocarbons which may be aromatic, such as styrene and alkylstyrenes, or aliphatic such as olefins, for example butene and diisobutylene. It is clear that the monomers must not contain units capable of being attacked by the electrolysis medium such as ester, amide, ether, keto and halogen atoms groups.
- Suitable monomers of this type which are not necessarily ionized under the conditions of electrolysis, include ethylenically unsaturated acids such as acrylic, methacrylic, crotonic, itaconic and maleic acids.
- Preferred polymers include those derived from 4-vinylpyridine and 4-styrene-sulfonic acid, especially the copolymers of 4-vinylpyridine and styrene and a poly (4-styrene-sulfonic acid) which is particularly preferred.
- these substances can be prepared using conventional polymerization techniques such as bulk, emulsion, precipitation and solution polymerization.
- the preferred polymers not only produce the required amount of foam without affecting the efficiency of the cell or the quality of the metal, but also are substantially attacked by the electrolyte.
- these polymers are compatible with licorice, gelatin (which promotes the formation of a smooth and even metallic deposit on the electrode) and a silicate, which have been traditionally used.
- the electrolyte ordinarily contains approximately 25 to 150 g / l, more particularly 40 to 60 g / l, of zinc and 75 to 250 g / l, more particularly 150 to 180 g / l, of free sulfuric acid, usually with an aluminum cathode and a lead anode containing, for example, 0.5 to 1% silver.
- the current density used in the recovery of zinc is 300 to 500 or 600 A / m2, generally with a cell voltage of 3.4 to 3.6 V, while for copper, it is approximately 200 A / m2.
- the working temperature is typically 35 to 40 ° C.
- polyelectrolyte used obviously depend to a certain extent on the nature of the substance, but amounts of 0.1 to 20 parts per million, in particular 0.25 to 5 parts per million are generally suitable.
- the ability of a foam to reduce the formation of acid fog is estimated qualitatively by keeping a wet strip of litmus paper about 3 cm above it. of the surface of the foam subjected to dynamic foaming.
- the thickness of foam in steady state is the thickness of foam obtained with an air flow of approximately 1 1 / min maintained for at least 30 min.
- the term “fleeting” designates a foam which collapses (when the supply of air bubbles stops) in less than 5 seconds; the term “unstable” designates a foam which persists for a maximum of 30 seconds; “average” applies to a foam life of 5 minutes maximum; “stable” indicates a foam life of up to 1 hour.
- a "good” barrier indicates that the color of litmus paper varied little if not at all in 1 minute; “medium” means that 2 to 5 isolated color spots have developed in 1 minute; “bad” means that large ranges of color have developed within 1 minute.
- Copoly (4-vinylpyridine / styrene) and poly (4-styrene-sodium sulfonate) were both found to be chemically stable in the electrolysis medium at room temperature and gave dynamic foam thicknesses under steady state conditions. 1-3 cm at concentrations of 0.002-0.01%. Foams were good covers against acid spraying. During storage, the copoly (4-vinylpyridine / styrene) gradually lost its foaming power, while the polysulfonate was not affected.
- the foaming power of the vinylpyridine polymer decreased progressively at 45 ° C (although it remained effective for at least 40 hours when added at a percentage of 0.01%) and decreased rapidly (> 24 h ) at 55 ° C.
- Sodium poly (4-styrene-sulfonate) was not affected by storage at 55 ° C for 2 days, the foam continuing to form a good barrier against acid fog.
- Poly (ethylene-imine) and 80% ethoxylated poly (ethylene-imine) had no effect on the foaming properties of the medium. It also appeared that oxidation by the medium occurred at the temperature ambient, as revealed by the disappearance of color (without precipitate) for the more concentrated solutions (0.1%).
- All the polymers are introduced into the electrolysis medium in an aqueous solution at 20% by weight.
- the concentration by weight of the polymer in the electrolysis medium is 10 p.p.m. (parts per milion).
- 90:10 means in the case for example of copoly (sodium 4-styrene sulfonate / acrylic acid), a copolymer comprising 90% by weight of sodium 4-styrene sulfonate and 10% by weight of acrylic acid.
- Different polymers are introduced at a concentration of 10 p.p.m. comprising several ionized species.
- the same polymer is introduced, namely poly (sodium 4-styrene sulfonate) at a concentration of 40 ppm, but having different molecular weights.
- poly (sodium 4-styrene sulfonate) at a concentration of 40 ppm, but having different molecular weights.
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Abstract
Description
La présente invention concerne les problèmes associés à la formation de brouillard acide au cours de la récupération électrolytique de métaux.The present invention relates to the problems associated with the formation of acid mist during the electrolytic recovery of metals.
Il est bien connu que l'électrolyse est utilisée tant pour la la galvanoplastie que pour la récupération de métaux. Dans le premier cas, le but est de déposer une couche lisse de métal sur le substrat ; on y parvient généralement en utilisant un bain électrolytique alcalin avec des densités de courant relativement faibles, de manière à déposer une couche de métal lentement et régulièrement. En revanche, dans la récupération électrolytique de la plupart des métaux, on applique des conditions fortement acides avec des densités de courant relativement élevées, car le but est de provoquer le dépôt du métal régénéré sur l'électrode de telle manière qu'il puisse en être facilement détaché par raclage.It is well known that electrolysis is used both for electroplating and for the recovery of metals. In the first case, the goal is to deposit a smooth layer of metal on the substrate; this is generally achieved by using an alkaline electrolytic bath with relatively low current densities, so as to deposit a layer of metal slowly and regularly. On the other hand, in the electrolytic recovery of most metals, strongly acidic conditions are applied with relatively high current densities, since the aim is to cause the deposition of the regenerated metal on the electrode in such a way that it can be easily detached by scraping.
Un principal problème associé aux procédés de récupération électrolytique, à la différence des procédés de galvanoplastie, est la formation d'un brouillard acide qui résulte du dégagement de gaz, principalement de l'hydrogène, au cours du processus d'électrolyse. Ce brouillard acide est un danger pour la santé et l'on a tenté de le supprimer par diverses méthodes. Celles-ci ont été aussi bien mécaniques que chimiques. Les traitements chimiques agissent habituellement en créant une couche superficielle de mousse sur l'électrolyte. Cette couche superficielle de mousse recouvre le brouillard et réduit ainsi les risques.A main problem associated with electrolytic recovery processes, unlike electroplating processes, is the formation of an acid mist which results from the evolution of gases, mainly hydrogen, during the electrolysis process. This acid mist is a health hazard and attempts have been made to remove it by various methods. These were both mechanical and chemical. Chemical treatments usually work by creating a surface layer of foam on the electrolyte. This surface layer of foam covers the fog and thus reduces the risks.
Divers agents tensio-actifs abaissant la tension superficielle ont été proposés à cet effet, y compris des alcane-sulfonates, des éthers d'alkylphénol et de polyglycol et des naphtalène-sulfonates, mais aucun d'entre eux ne s'est montré tout à fait satisfaisant car les conditions requises d'une substance satisfaisante sont très rigoureuses.Various surface tension-lowering surfactants have been proposed for this purpose, including alkane sulfonates, alkylphenol and polyglycol ethers, and naphthalene sulfonates, but none of them has been shown to be effective. satisfactory because the requirements for a satisfactory substance are very stringent.
On se rendra compte qu'il est important de maîtriser le niveau de mousse car si celle-ci est trop épaisse, elle risque d'emprisonner l'hydrogène qui est libéré. Par contre, si elle est trop mince, elle ne remplit pas sa fonction prévue. En général, la couche de mousse doit avoir une épaisseur d'environ 2 cm. En pratique, il se révèle généralement nécessaire d'utiliser un agent antimousse conjointement à ces agents tensio-actifs afin de parvenir à la hauteur de mousse appropriée. En outre, il a été constaté qu'un grand nombre de ces agents tensio-actifs sont attaqués par la nature fortement acide et oxydante de l'électrolyte tandis que d'autres affectent l'efficacité de la cellule d'électrolyse et la qualité du dépôt métallique. A cet égard, il importe que l'agent moussant n'interfère pas avec le "bord" du dépôt métallique, car ce bord est nécessaire si le dépôt doit être détaché efficacement de l'électrode par des ciseaux mécaniques. Enfin, il est souhaitable que l'agent moussant soit efficace à des températures allant jusqu'à 50°C environ, car il est difficile de maintenir les cellules très au-dessous de cette température, notamment par temps chaud. Il est souhaitable que la concentration atmosphérique d'acide sulfurique (l'acide normalement utilisé) ne soit pas supérieure à 1 mg.m⁻3.We will realize that it is important to control the level of foam because if it is too thick, it may trap the hydrogen that is released. On the other hand, if it is too thin, it does not fulfill its intended function. In general, the foam layer should be about 2 cm thick. In practice, it generally proves necessary to use an antifoaming agent in conjunction with these surfactants in order to achieve the appropriate foam height. In addition, it has been found that many of these surfactants are attacked by the strongly acidic and oxidative nature of the electrolyte while others affect the efficiency of the electrolysis cell and the quality of the electrolyte. metallic deposit. In this respect, it is important that the foaming agent does not interfere with the "edge" of the metal deposit, since this edge is necessary if the deposit must be effectively detached from the electrode by mechanical scissors. Finally, it is desirable for the foaming agent to be effective at temperatures of up to approximately 50 ° C., since it is difficult to keep the cells very below this temperature, especially in hot weather. It is desirable that the atmospheric concentration of sulfuric acid (the acid normally used) is not more than 1 mg.m⁻3.
En pratique, l'agent moussant le plus généralement utilisé est la réglisse. Celle-ci produit une mousse robuste, bien maîtrisée, qui n'affecte pas excessivement l'efficacité de la cellule ou la qualité du métal produit. Malheureusement, elle n'est pas efficace comme agent moussant aux températures supérieures à 38°C environ. Cela limite sévèrement son utilisation car il est difficile et coûteux de maintenir la température à cette valeur par temps chaud. On a donc besoin d'une substance qui produise le niveau désirée de mousse et qui soit stable dans les conditions d'électrolyse jusqu'à des 35 températures de l'ordre de 50°C.In practice, the most commonly used foaming agent is licorice. This produces a robust foam, well controlled, which does not excessively affect the efficiency of the cell or the quality of the metal produced. Unfortunately, it is not effective as a foaming agent at temperatures above about 38 ° C. This severely limits its use since it is difficult and expensive to maintain the temperature at this value in hot weather. There is therefore a need for a substance which produces the desired level of foam and which is stable under the conditions of electrolysis up to temperatures of the order of 50 ° C.
Selon la présente invention, on a maintenant découvert que ces résultats peuvent être atteints non par l'utilisation d'agents tensio-actifs classiques abaissant la tension superficielle, mais par l'utilisation d'électrolytes polymères. On pense que ces polyélectrolytes agissent en exerçant un effet d'augmentation de viscosité superficielle sur les lamelles de mousse conjugué à un effet suffisant d'abaissement de la tension superficielle, sans produire d'abondantes quantités de mousse ; l'augmentation de viscosité diminue l'écoulement et, par suite, prolonge la vie de la mousse.According to the present invention, it has now been discovered that these results can be achieved not by the use of conventional surfactants lowering the surface tension, but by the use of polymer electrolytes. It is believed that these polyelectrolytes act by exerting an effect of increasing surface viscosity on the foam strips combined with a sufficient effect of lowering the surface tension, without producing abundant amounts of foam; the increase in viscosity decreases the flow and, consequently, prolongs the life of the foam.
Selon la présente invention, il est fourni un procédé pour la récupération électrolytique d'un métal qui consiste à électrolyser une solution acide du métal, la solution contenant, à l'état dissous, un polyélectrolyte anionique ou cationique qui est ionisé dans les conditions d'électrolyse employées et dont la molécule possède un fragment hydrophobe de sorte que la tension superficielle de la surface du bain soit suffisamment réduite pour produire une mousse. De préférence, le polyélectrolyte possède également un fragment hydrophile qui n'est pas ionisé dans les conditions d'électrolyse ; on pense que ce fragment hydrophile peut améliorer la solubilité du polyélectrolyte.According to the present invention, there is provided a method for the electrolytic recovery of a metal which consists in electrolyzing an acidic solution of the metal, the solution containing, in the dissolved state, an anionic or cationic polyelectrolyte which is ionized under the conditions of 'electrolysis employed and whose molecule has a hydrophobic fragment so that the surface tension of the surface of the bath is sufficiently reduced to produce a foam. Preferably, the polyelectrolyte also has a hydrophilic fragment which is not ionized under the conditions of electrolysis; it is believed that this hydrophilic moiety can improve the solubility of the polyelectrolyte.
La présente invention est applicable à la récupération électrolytique de métaux qui peuvent être récupérés dans des conditions acides, typiquement en utilisant l'acide sulfurique. Ces métaux comprennent le cobalt, le nickel, le chrome, le thallium et l'indium et, en particulier, le zinc, le cadmium, le cuivre et le manganèse, par exemple. La description qui suit se réfère en particulier au zinc, mais l'homme de l'art se rendra compte qu'en apportant des modifications de routine l'invention peut s'appliquer aux autres métaux qui peuvent être récupérés en effectuant une électrolyse acide.The present invention is applicable to the electrolytic recovery of metals which can be recovered under acidic conditions, typically using sulfuric acid. These metals include cobalt, nickel, chromium, thallium and indium and, in particular, zinc, cadmium, copper and manganese, for example. The following description refers in particular to zinc, but those skilled in the art will realize that by making routine modifications the invention can be applied to other metals which can be recovered by carrying out acid electrolysis.
Les polyélectrolytes utilisés dans la présente invention sont de préférence ceux dans lesquels les groupes iosinants ne font pas partie du squelette du polymère mais se présentent comme des groupes latéraux. Des polyélectrolytes particulièrement préférés sont les polymères contenant des groupes latéraux sulfonate, généralement dérivés d'acide styrène-sulfonique ou d'un sels de celui-ci en tant que monomère. On notera cependant que le groupement fonctionnel peut être anionique ou cationique. D'autres monomères qui peuvent être utilisés comprennent l'acide vinylsulfonique, l'acide vinylphosphonique, l'acide 2-acrylamidométhylpropane-sulfonique et les 2- et 4-vinylpyridines, et leurs sels, généralement le sel de sodium.The polyelectrolytes used in the present invention are preferably those in which the iosinating groups are not part of the polymer backbone but are presented as side groups. Particularly preferred polyelectrolytes are polymers containing sulfonate side groups, generally derived from styrene sulfonic acid or a salt thereof as a monomer. Note however that the functional group can be anionic or cationic. Other monomers which can be used include vinylsulfonic acid, vinylphosphonic acid, 2-acrylamidomethylpropane-sulfonic acid and 2- and 4-vinylpyridines, and their salts, generally the sodium salt.
Le poids moléculaire du polyélectrolyte n'est pas particulièrement déterminant ; des valeurs de 10⁴ à 10⁷, notamment de 10⁵ à 10⁶, sont généralement appropriées.The molecular weight of the polyelectrolyte is not particularly critical; values from 10⁴ to 10⁷, especially from 10⁵ to 10⁶, are generally appropriate.
Le polyélectrolyte utilisé dans la présente invention peut être un homopolymère ou un copolymère. On notera que l'équilibre entre l'effet d'abaissement de la tension superficielle et l'effet d'augmentation de viscosité peut être modifié en choisissant les proportions relatives du motif hydrophobe et de tout motif hydrophile qui peut être inclus.The polyelectrolyte used in the present invention can be a homopolymer or a copolymer. It will be noted that the balance between the effect of lowering the surface tension and the effect of increasing viscosity can be modified by choosing the relative proportions of the hydrophobic unit and any hydrophilic unit which may be included.
Des monomères hydrophobes appropriés que l'on peut utiliser pour obtenir les copolymères comprennent des hydrocarbures éthyléniquement insaturés qui peuvent être aromatiques, tels que le styrène et les alkylstyrènes, ou aliphatiques tels que les oléfines, par exemple le butène et le diisobutylène. Il est clair que les monomères ne doivent pas contenir de motifs susceptibles d'être attaqués par le milieu d'électrolyse tels que des groupes ester, amide, éther, céto et des atomes d'halogènes.Suitable hydrophobic monomers which can be used to obtain the copolymers include ethylenically unsaturated hydrocarbons which may be aromatic, such as styrene and alkylstyrenes, or aliphatic such as olefins, for example butene and diisobutylene. It is clear that the monomers must not contain units capable of being attacked by the electrolysis medium such as ester, amide, ether, keto and halogen atoms groups.
La présence de fragments hydrophiles dans les polymères améliore la solubilité. Des monomères appropriés de ce type, quine sont pas nécessairement ionisés dans les conditions d'électrolyse, comprennent des acides éthyléniquement insaturés tels que les acides acrylique, méthacrylique, crotonique, itaconique et maléique.The presence of hydrophilic fragments in the polymers improves the solubility. Suitable monomers of this type, which are not necessarily ionized under the conditions of electrolysis, include ethylenically unsaturated acids such as acrylic, methacrylic, crotonic, itaconic and maleic acids.
L'homme de l'art reconnaîtra évidemment qu'il est aisé de faire varier les proportions des motifs dans le copolymère pour obtenir les effets de tension superficielle et d'augmentation de viscosité souhaités, ces derniers étant réalisés principalement en ajustant le poids moléculaire du polymère.Those skilled in the art will obviously recognize that it is easy to vary the proportions of the patterns in the copolymer to obtain the desired surface tension and viscosity increase effects, the latter being produced mainly by adjusting the molecular weight of the polymer.
Les polymères préférés comprennent ceux dérivés de la 4-vinylpyridine et de l'acide 4-styrène-sulfonique, notamment les copolymères de 4-vinylpyridine et de styrène et un poly(acide 4-styrène-sulfonique) qui est particulièrement préféré.Preferred polymers include those derived from 4-vinylpyridine and 4-styrene-sulfonic acid, especially the copolymers of 4-vinylpyridine and styrene and a poly (4-styrene-sulfonic acid) which is particularly preferred.
On notera que ces substances peuvent être préparées en utilisant des techniques classiques de polymérisation telles que la polymérisation en masse, en émulsion, par précipitation et en solution.Note that these substances can be prepared using conventional polymerization techniques such as bulk, emulsion, precipitation and solution polymerization.
Il a été constaté que les polymères préférés non seulement produisent la quantité requise de mousse sans affecter l'efficacité de la cellule ou la qualité du métal, mais également sont sensiblement inattaqués par l'électrolyte. En outre, il a été constaté que ces polymères sont compatibles avec la réglisse, la gélatine (qui favorise la formation d'un dépôt métallique lisse et égal sur l'électrode) et un silicate, qui ont été traditionnellement employés.It has been found that the preferred polymers not only produce the required amount of foam without affecting the efficiency of the cell or the quality of the metal, but also are substantially attacked by the electrolyte. In addition, it has been found that these polymers are compatible with licorice, gelatin (which promotes the formation of a smooth and even metallic deposit on the electrode) and a silicate, which have been traditionally used.
Dans la récupération électrolytique du zinc, l'électrolyte contient ordinairement environ 25 à 150 g/l, plus particulièrement 40 à 60 g/l, de zinc et 75 à 250 g/l, plus particulièrement 150 à 180 g/l, d'acide sulfurique libre, en général avec une cathode en aluminium et une anode en plomb contenant, par exemple, 0,5 à 1 % d'argent. D'autre part, pour le cuivre par exemple, on utilise généralement 25 à 30 g/l de cuivre avec une quantité similaire d'acide sulfurique libre. Typiquement, la densité de courant utilisée dans la récupération du zinc est de 300 à 500 ou 600 A/m², généralement avec une tension de cellule de 3,4 à 3,6 V, tandis que pour le cuivre, elle est d'environ 200 A/m². La température de travail est typiquement de 35 à 40°C.In the electrolytic recovery of zinc, the electrolyte ordinarily contains approximately 25 to 150 g / l, more particularly 40 to 60 g / l, of zinc and 75 to 250 g / l, more particularly 150 to 180 g / l, of free sulfuric acid, usually with an aluminum cathode and a lead anode containing, for example, 0.5 to 1% silver. On the other hand, for copper for example, generally 25 to 30 g / l of copper are used with a similar amount of free sulfuric acid. Typically, the current density used in the recovery of zinc is 300 to 500 or 600 A / m², generally with a cell voltage of 3.4 to 3.6 V, while for copper, it is approximately 200 A / m². The working temperature is typically 35 to 40 ° C.
Les quantités de polyélectrolyte utilisées dépendent évidemment dans une certaine mesure de la nature de la substance, mais des quantités de 0,1 à 20 parties par million, notamment de 0,25 à 5 parties par million- sont généralement appropriées.The amounts of polyelectrolyte used obviously depend to a certain extent on the nature of the substance, but amounts of 0.1 to 20 parts per million, in particular 0.25 to 5 parts per million are generally suitable.
Les Exemples suivants illustrent davantage la présente invention.The following Examples further illustrate the present invention.
On utilise le milieu synthétique d'électrolyse suivant :
Divers polymères sont ajoutés au milieu d'électrolyse et mis à l'essai. Le pouvoir moussant dynamique est examiné par insufflation de bulles d'air dans le milieu auquel la solution de polymère a été appliquée au moyen d'un distributeur en verre fritté de porosité 3. Pour certains, les propriétés de moussage sont également étudiées par une méthode des normes ASTM (Méthode de la Hauteur de Mousse " Ross-Miles").Various polymers are added to the electrolysis medium and tested. The dynamic foaming power is examined by blowing air bubbles into the medium to which the polymer solution has been applied by means of a sintered glass distributor of porosity 3. For some, the foaming properties are also studied by a method ASTM standards (Ross-Miles Foam Height Method).
L'aptitude d'une mousse à réduire la formation de brouillard acide est estimée qualitativement en maintenant un ruban humide de papier tournesol à environ 3 cm au-dessus de la surface de la mousse soumise au moussage dynamique.The ability of a foam to reduce the formation of acid fog is estimated qualitatively by keeping a wet strip of litmus paper about 3 cm above it. of the surface of the foam subjected to dynamic foaming.
Les résultats obtenus peuvent être trouvés dans les Tableaux suivants qui incluent l'effet du stockage et de la température sur les résultats. Les polymères examinés sont détaillés ci-dessous :
Copoly(4-vinylpyridine/styrène) (teneur en styrène : 10 %), poudre (Aldrich)
Poly(éthylène-imine), solution à 50 % en poids dans l'eau. P.M. moyen = 50 000 à 60 000 (Aldrich).
Poly(éthylène-imine) éthoxylée à 80 %, solution à 37 % en poids dans l'eau. P.M. du polymère de base = 5000 (Aldrich).
Poly( 4-styrène-sulfonate de sodium ), solution à 20 % en poids dans l'eau (Aldrich). P. M. approximatif = 4 x 10⁵.
Copoly (4-vinylpyridine / styrene) (styrene content: 10%), powder (Aldrich)
Poly (ethyleneimine), 50% by weight solution in water. Average PM = 50,000 to 60,000 (Aldrich).
Poly (ethyleneimine) ethoxylated at 80%, solution at 37% by weight in water. MS of the base polymer = 5000 (Aldrich).
Poly (sodium 4-styrene sulfonate), 20% by weight solution in water (Aldrich). Approximate PM = 4 x 10⁵.
Sur le Tableau 1, l'épaisseur de mousse en régime permanent est l'épaisseur de mousse obtenue avec un débit d'air d'environ 1 1/min maintenu pendant au moins 30 min. Le terme "fugace" désigne une mousse qui s'effondre (à l'arrêt de l'alimentation en bulles d'air ) en moins de 5 secondes ; le terme "instable" désigne une mousse qui persiste 30 secondes au maximum ; "moyenne" s'applique à une vie de mousse de 5 minutes au maximum ; "stable" indique une durée de vie de mousse allant jusqu'à 1 heure. Dans l'essai concernant la formation de brouillard acide, une barrière "bonne" indique que la couleur du papier tournesol a peu sinon pas du tout varié en 1 minute ; "moyenne" signifie que 2 à 5 taches de couleur isolées se sont développés en 1 minute ; "mauvaise" signifie que de grandes plages de couleur se sont développées en 1 minute.In Table 1, the thickness of foam in steady state is the thickness of foam obtained with an air flow of approximately 1 1 / min maintained for at least 30 min. The term "fleeting" designates a foam which collapses (when the supply of air bubbles stops) in less than 5 seconds; the term "unstable" designates a foam which persists for a maximum of 30 seconds; "average" applies to a foam life of 5 minutes maximum; "stable" indicates a foam life of up to 1 hour. In the test for the formation of acid fog, a "good" barrier indicates that the color of litmus paper varied little if not at all in 1 minute; "medium" means that 2 to 5 isolated color spots have developed in 1 minute; "bad" means that large ranges of color have developed within 1 minute.
Le copoly(4-vinylpyridine/styrène) et le poly(4-styrène-sulfonate de sodium) se sont montrés tous deux chimiquement stables dans le milieu d'électrolyse à la température ambiante et ont donné des épaisseurs de mousse dynamiques en régime permanent de 1-3 cm à des concentrations de 0,002-0,01 %. Les mousses constituaient de bonnes couvertures contre la pulvérisation d'acide. Au stockage, le copoly(4-vinylpyridine/styrène) a perdu progressivement son pouvoir moussant, tandis que le polysulfonate n'a pas été affecté. De même, le pouvoir moussant du polymère de vinylpyridine a diminué progressivement à 45°C (bien qu'il soit resté efficace pendant au moins 40 heures en étant ajouté à un pourcentage de 0,01 %) et a diminué rapidement (>24 h) à 55°C. Le poly(4-styrène-sulfonate de sodium) n'a pas été affecté par un stockage à 55°C pendant 2 jours, la mousse continuant à former une bonne barrière contre le brouillard acide.Copoly (4-vinylpyridine / styrene) and poly (4-styrene-sodium sulfonate) were both found to be chemically stable in the electrolysis medium at room temperature and gave dynamic foam thicknesses under steady state conditions. 1-3 cm at concentrations of 0.002-0.01%. Foams were good covers against acid spraying. During storage, the copoly (4-vinylpyridine / styrene) gradually lost its foaming power, while the polysulfonate was not affected. Likewise, the foaming power of the vinylpyridine polymer decreased progressively at 45 ° C (although it remained effective for at least 40 hours when added at a percentage of 0.01%) and decreased rapidly (> 24 h ) at 55 ° C. Sodium poly (4-styrene-sulfonate) was not affected by storage at 55 ° C for 2 days, the foam continuing to form a good barrier against acid fog.
La poly(éthylène-imine) et la poly(étylène-imine) éthoxylée à 80 % n'avaient pas d'effet sur les propriétés de moussage du milieu. Il est également apparu qu'une oxydation par le milieu se produisait à la température ambiante, comme révélé par la disparition de couleur (sans précipité) pour les solutions plus concentrées (0,1%).Poly (ethylene-imine) and 80% ethoxylated poly (ethylene-imine) had no effect on the foaming properties of the medium. It also appeared that oxidation by the medium occurred at the temperature ambient, as revealed by the disappearance of color (without precipitate) for the more concentrated solutions (0.1%).
D'après le Tableau 2, on peut voir que les deux agents tensio-actifs non polymères offrent un moussage beaucoup plus important et des mousses bien plus stables.From Table 2, it can be seen that the two non-polymeric surfactants provide much greater foaming and much more stable foams.
Des essais à l'échelle réelle ont montré que des quantités bien plus faibles des polyélectrolytes sont efficaces. Ainsi, on a constaté que le poly(4-styrène-sulfonate de sodium) agit de façon satisfaisante dans une installation en vraie grandeur à une concentration de 1 partie par million.Full scale tests have shown that much lower amounts of the polyelectrolytes are effective. Thus, it has been found that poly (sodium 4-styrene-sulfonate) acts satisfactorily in a full-scale installation at a concentration of 1 part per million.
Dans les exemples suivants, on utilise toujours le même milieu d'électrolyse décrit en détail ci-dessus dans les exemples précédents et le pouvoir moussant est également examiné par insufflation de bulles d'air dans le milieu auquel la solution de polymère a été appliquée au moyen d'un distributeur en verre fritté de porosité 3.In the following examples, the same electrolysis medium described in detail above in the preceding examples is always used and the foaming power is also examined by blowing air bubbles into the medium to which the polymer solution has been applied to the using a sintered glass dispenser with porosity 3.
Tous les polymères sont introduits dans le milieu d'électrolyse en solution aqueuse à 20 % en poids.All the polymers are introduced into the electrolysis medium in an aqueous solution at 20% by weight.
On introduit différents polymères comportant des parties hydrophiles et non ionisés dans les conditions électrolytiques.Various polymers are introduced comprising hydrophilic and non-ionized parts under the electrolytic conditions.
La concentration en poids du polymère dans le milieu d'électrolyse est de 10 p.p.m. (parties par milion).The concentration by weight of the polymer in the electrolysis medium is 10 p.p.m. (parts per milion).
Les résultats obtenus sont rassemblés dans le tableau 3 ci-après
90:10 veut dire dans le cas par exemple du copoly(4-styrène sulfonate de sodium/acide acrylique), un copolymère comportant 90 % en poids de 4-styrène sulfonate de sodium et 10 % en poids d'acide acrylique.90:10 means in the case for example of copoly (sodium 4-styrene sulfonate / acrylic acid), a copolymer comprising 90% by weight of sodium 4-styrene sulfonate and 10% by weight of acrylic acid.
Du tableau 3, il apparaît que la hauteur de mousse peut être réglée par la sélection de comomères hydrophiles non ionisés.From Table 3, it appears that the foam height can be adjusted by the selection of non-ionized hydrophilic comomers.
On introduit différents polymères comportant des parties hydrophobes à la concentration de 10 p.p.m. Les résultats obtenus sont rassemblés dans le tableau 4 ci-après.
Du tableau 4, il pparaît que la hauteur de la mousse peut être réglée par l'incorporation d'un comonomère hydrophobe.From Table 4, it appears that the height of the foam can be adjusted by incorporating a hydrophobic comonomer.
On introduit différents polymères à une concentration de 10 p.p.m. comportant plusieurs espèces ionisées.Different polymers are introduced at a concentration of 10 p.p.m. comprising several ionized species.
Les résultats obtenus sont rassemblés dans le tableau 5 ci-après.
Il ressort du tableau 5 que l'on peut régler la hauteur de la mousse en copolymérisant plusieurs espèces ionisées sous les conditions électrolytiques. Comme on pouvait le prévoir, l'effet n'est pas aussi important qu'avec des comonomères non ionisés.It appears from Table 5 that the height of the foam can be adjusted by copolymerizing several ionized species under the electrolytic conditions. As expected, the effect is not as great as with non-ionized comonomers.
On introduit le même polymère, à savoir le poly(4-styrène sulfonate de sodium) à une concentration de 40 p.p.m., mais présentant des poids moléculaires différents. Les résultats sont rassemblés dans le tableau 6 ci-après.
Du tableau 6, il apparaît qu'on peut contrôler la hauteur de mousse et sa stabilité, en règlant le poids moléculaire du polymère.From Table 6, it can be seen that the height of the foam and its stability can be controlled by adjusting the molecular weight of the polymer.
En faisant varier les paramètres illustrés dans les 4 séries d'essais ci-dessus, on voit que l'on peut choisir un polymère qui soit adapté à l'obtention d'une hauteur de mousse et d'une stabilité de mousse optimum pour un système donné.By varying the parameters illustrated in the 4 series of tests above, it can be seen that a polymer can be chosen which is suitable for obtaining an optimum foam height and foam stability for a given system.
Claims (11)
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB9025780A GB2250515B (en) | 1990-11-27 | 1990-11-27 | Controlling acid misting during electrolytic recovery of metals |
| GB9025780 | 1990-11-27 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| EP0488862A1 true EP0488862A1 (en) | 1992-06-03 |
Family
ID=10686066
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| EP91403156A Ceased EP0488862A1 (en) | 1990-11-27 | 1991-11-22 | Prevention against acid mist in metal electrowinning |
Country Status (5)
| Country | Link |
|---|---|
| EP (1) | EP0488862A1 (en) |
| JP (1) | JPH0794717B2 (en) |
| CA (1) | CA2056822A1 (en) |
| FI (1) | FI915562A (en) |
| GB (1) | GB2250515B (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1995030783A1 (en) * | 1994-05-05 | 1995-11-16 | Minnesota Mining And Manufacturing Company | Mist suppressant for solvent extraction metal electrowinning |
| US6258245B1 (en) * | 1998-11-19 | 2001-07-10 | Betzdearborn Inc. | Copper leach process aids |
| US11807952B2 (en) | 2021-10-07 | 2023-11-07 | Freeport Minerals Corporation | Acid mist suppression in copper electrowinning |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| PL2845928T3 (en) | 2013-09-05 | 2020-05-18 | Macdermid Enthone Inc. | Aqueous electrolyte composition having a reduced airborne emission |
| RU2628946C2 (en) * | 2015-10-29 | 2017-08-23 | Игорь Владимирович Федосеев | PREPARATION METHOD OF PURE ELECTROLYTIC CONDUCTOR CuSo4 FROM MULTICOMPONENT SOLUTIONS AND ITS REGENERATION, WHEN PRODUCING CATHODE COPPER BY ELECTROLYSIS WITH INSOLUBLE ANODE |
| RU2667927C1 (en) * | 2017-12-28 | 2018-09-25 | Общество С Ограниченной Ответственностью "Сдп-М" | Method of producing of high purity copper |
| WO2020188839A1 (en) * | 2019-03-20 | 2020-09-24 | 東ソー・ファインケム株式会社 | Novel polystyrene-based polyampholyte having upper critical solution temperature, and application for same |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2913377A (en) * | 1956-06-11 | 1959-11-17 | Udylite Res Corp | Aqueous electrolytic process |
| US2978394A (en) * | 1958-02-25 | 1961-04-04 | American Cyanamid Co | Polyelectrolytes in electrolysis |
| EP0027322A1 (en) * | 1979-10-10 | 1981-04-22 | Inco Limited | Process of electrowinning metals |
| GB2077765A (en) * | 1980-06-16 | 1981-12-23 | Minnesota Mining & Mfg | Mist suppressant |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1102692A (en) * | 1964-03-03 | 1968-02-07 | Canning And Company Ltd W | Fluorinated aromatic compounds |
| US3657080A (en) * | 1968-09-25 | 1972-04-18 | M & T Chemicals Inc | Mist suppression in electroplating solutions |
| SU579348A1 (en) * | 1976-06-28 | 1977-11-05 | Норильский Ордена Ленина И Ордена Трудового Красного Знамени Горнометаллургический Комбинат Им.А.П. Завенягина | Method of decoppering solutions by obtaining froth protection layers on electrolyte surface |
| SU596661A1 (en) * | 1976-12-06 | 1978-03-05 | Всесоюзный Ордена Трудового Красного Знамени Научно-Исследовательский Горнометаллургический Институт Цветных Металлов "Вниицветмет" | Method of zinc plating |
| US4770814A (en) * | 1983-08-31 | 1988-09-13 | The Dow Chemical Company | Shear stable antimisting formulations |
-
1990
- 1990-11-27 GB GB9025780A patent/GB2250515B/en not_active Expired - Fee Related
-
1991
- 1991-11-18 JP JP3328295A patent/JPH0794717B2/en not_active Expired - Fee Related
- 1991-11-22 EP EP91403156A patent/EP0488862A1/en not_active Ceased
- 1991-11-26 FI FI915562A patent/FI915562A/en not_active Application Discontinuation
- 1991-11-26 CA CA 2056822 patent/CA2056822A1/en not_active Abandoned
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2913377A (en) * | 1956-06-11 | 1959-11-17 | Udylite Res Corp | Aqueous electrolytic process |
| US2978394A (en) * | 1958-02-25 | 1961-04-04 | American Cyanamid Co | Polyelectrolytes in electrolysis |
| EP0027322A1 (en) * | 1979-10-10 | 1981-04-22 | Inco Limited | Process of electrowinning metals |
| GB2077765A (en) * | 1980-06-16 | 1981-12-23 | Minnesota Mining & Mfg | Mist suppressant |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1995030783A1 (en) * | 1994-05-05 | 1995-11-16 | Minnesota Mining And Manufacturing Company | Mist suppressant for solvent extraction metal electrowinning |
| US6258245B1 (en) * | 1998-11-19 | 2001-07-10 | Betzdearborn Inc. | Copper leach process aids |
| US11807952B2 (en) | 2021-10-07 | 2023-11-07 | Freeport Minerals Corporation | Acid mist suppression in copper electrowinning |
| US12098474B2 (en) | 2021-10-07 | 2024-09-24 | Freeport Minerals Corporation | Acid mist suppression in copper electrowinning |
Also Published As
| Publication number | Publication date |
|---|---|
| FI915562A (en) | 1992-05-28 |
| GB2250515A (en) | 1992-06-10 |
| GB2250515B (en) | 1994-09-28 |
| JPH06220678A (en) | 1994-08-09 |
| CA2056822A1 (en) | 1992-05-28 |
| JPH0794717B2 (en) | 1995-10-11 |
| GB9025780D0 (en) | 1991-01-09 |
| FI915562A0 (en) | 1991-11-26 |
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