WO1983003627A1 - Method and apparatus for reclaiming zinc from industrial zinc-bearing waste metal - Google Patents
Method and apparatus for reclaiming zinc from industrial zinc-bearing waste metal Download PDFInfo
- Publication number
- WO1983003627A1 WO1983003627A1 PCT/BE1983/000009 BE8300009W WO8303627A1 WO 1983003627 A1 WO1983003627 A1 WO 1983003627A1 BE 8300009 W BE8300009 W BE 8300009W WO 8303627 A1 WO8303627 A1 WO 8303627A1
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- WIPO (PCT)
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- zinc
- mercury
- electrolysis cell
- waste
- electrically connected
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Classifications
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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
- C25C5/00—Electrolytic production, recovery or refining of metal powders or porous metal masses
- C25C5/02—Electrolytic production, recovery or refining of metal powders or porous metal masses from solutions
Definitions
- the present invention relates to an industrial technique for the recovery of zinc and possibly other components or constituents of industrial zinciferous waste, for example steel.
- zinciferous waste is meant here any industrial residual product or solutio obtained from industrial residues.
- the invention provides an attractive industrial solution which fills this gap by means of a process characterized in that the zinciferous waste is immersed in a first solution, preferably alkaline, in the presence of a sheet of mercury and an electrically connected electrode. at a positive electrical potential then, by electrolysis, zinc is deposited cathodically from the zinciferous waste to form a zinc amalgam. The zinc amalgam is then separated from the first solution and the zinc amalgam is brought into contact with a second acidic, neutral or complexing solution in the presence of a cathode electrically connected to a negative electrical potential. By electrolysis, the zinc of the amalgam is then redissolved anodically to produce a deposit of pure zinc on the cathode.
- a first solution preferably alkaline
- an electrically connected electrode at a positive electrical potential then, by electrolysis, zinc is deposited cathodically from the zinciferous waste to form a zinc amalgam.
- the zinc amalgam is then separated from the first solution and the zinc amalgam is brought into contact with a second
- the bottom of the tank etan covered with a layer of mercury in forced circulation, extending in the bottom of the two 'compartment through the aforementioned opening 1 , the first compartment containing a first electrolyte in which is immersed an electrode electrically connected to a positive electrical potential, the second compartment containing a second electrolyte in which is immersed one. cathode connected to a negative electrical potential, the sheet of mercury constituting both a mechanical barrier to avoid mixing of the two electrolytes and a selective electrochemical barrier vis-à-vis the ions to be separated.
- the electrolyte contained in the anode compartment is, without this factor being limiting, preferably an alkaline solution, for example a solution of NaOH, and the electrolyte contained in the cathode compartment is an acidic, neutral or complexing solution, for example a zinc sulfa solution or an electroplating bath.
- the electrodes can be connected electrically. ment to the poles of the same source of electrical voltage or to separate sources of electrical voltage.
- the technique according to the invention allows easy recovery of zinc and steel from galvanized sheet waste with in particular the following advantages: a.
- the dissolution and electrolysis reactions are carried out with a very high yield at ordinary temperature and with low energy consumption.
- the equipment required is very simple.
- the consumption of reagents is very low since we simply have to compensate for the losses due to the presence of possible impurities (for example solubillation of traces of aluminum).
- Zinc is obtained in compact mono-crystalline form stable, easily fusible and valuable. It can also be recovered in one of the variants of the procedure in the form of a coating of steel sheets (electrolytic zinc coating). 5 e. Steel free of zinc can be recycled into steel without problems, f. Absence of any problem of discharge of polluting waste gases or dust.
- the technique according to the invention also allows the production of pure zinc recoverable by recovery of various industrial zinciferous waste: residual dust from electrical steelworks (which contain appreciable zinc contents of up to 20% and more), 5 residual dust blast furnaces, galvation attes and even zinc ores leached with soda. This technique thus gives significant added value to all this residual waste.
- An additional advantage of the electrolysis cell according to the invention is that it allows both electrolytic recovery and electro-refining of zinc to be carried out in a single operation.
- this cell makes it possible to produce galvanizing chains capable of working with low-cost starting materials, which provides substantial savings in raw materials.
- Figure 1 is a cross-sectional view of an example cell according to the invention.
- Figure 2 is a top view of the cell of Figure 1.
- the technique according to the invention is based on the technolo called metallurgy of amalgams which consists in using a mercury electrode to extract a metal from an alloy or a compound.
- This technique is implemented in an electrolysis cell as shown for example in the drawings.
- the cell 10 comprises two compartments, 2 separated by a partition 3 and communi ⁇ as between them by an opening 4 formed in the lower part of the partition 3.
- a sheet of mercury 5 which extends in the two compartments 1 and 2 through the opening 4 and which is maintained in forced circulation by a pump 11.
- the first compartment " 1 contains an electrolyte 6 in which is immersed an electrode 7 electrically connected to a source of potential positive electric + V.
- the electrode 7 consists of a conveyor chain circulating in the electrolytic bath at a certain distance above the sheet of mercury and is intended to carry the hazardous waste to be treated.
- the electrolyte 6 is preferably but without this factor being limiting, an alkaline solution, for example a NaOH solution.
- the anode electrode 7 could also be a rotating basket for example, which would immerse the waste to be treated in the electrolyte 6. In other embodiments, the anode electrode could be provided so as not to carry the zinciferous waste to be treated.
- the zinciferous waste to be treated is immersed in the trolyte ele 6 of the anode compartment 1.
- the waste is either directly metallic waste (galvanized sheets, galvanizing rods) or -a zinciferous solution obtained by chemical treatment of dust. aci ries, blast furnace sludge or zinc ores by "example. ,
- the mercury pool 5 operates as the cathode.
- zinc is deposited cathodically and amalgamates with mercury.
- the nature of the anodic reaction in compartment 1 can be judiciously selected by the arrangement of this compartment 5 depending on the nature of the waste to be treated.
- an anodic steel electrode is chosen, immersed in a NaOH solution. Electrochemical dissolution of the zinc then takes place in the trolyte ele.
- the anodic reaction causes oxygen to be released.
- Table 25 Table the zinc of industrial residues such as steelworks dust, blast furnace sludge, galvanizing mattes, galvanized sheet waste for example.
- electrolysis in an alkaline medium makes it possible to eliminate the problems associated with the evolution of hydrogen which does not manifest itself with the same acuity as in an acid medium due to the high pH.
- the zinc amalgam formed in compartment 1 passes into cathode compartment 2 with the mercurial blanket 5 5 in circulation.
- the compartment 2 contains a proper electrolytic consisting of a solution of acid, neutral
- ⁇ MP complexing according to the applications.
- a cathode 9 electrically connected to a negative electric pot -V.
- the electrolyte 8 is for example a solution of zinc sulfate in which an aluminum cathode is immersed.
- the zinc of the amalgam ée redis anodically sustained in the electrolyte 8 and the dissolved zinc is deposited on the cathode 9 in a pure, stable and non-oxidizable mono-crystalline form, which has an interesting value.
- the cathode compartment may also 'be an electrolytic galvanizing compartment.
- an electroplating bath is chosen for the electrolyte (alkaline cyanide bath or acid bath for example) and the support of the steel to be galvanized is used as the cathode. zinc is then deposited directly on the steel in the form of a galvanizing coating.
- the electrolytic cell according to the invention thus makes it possible to constitute a particularly economical direct galvanizing station thanks to the use of zinc recovered from zinciferous waste. Note that the electrolysis cell eliminates the presence of sludge in the cathode compartment.
- a remarkable feature of the lectrolys cell according to the invention is that the sheet of mercury 5 plays the role of a bipolar electrode which is permeable to amalgamable elements such as zinc, lead, bismuth, tin for example contained in the compartment anode 1 and which is impermeable to ions and. solvent.
- the mercury sheet thus constitutes both a mechanical barrier preventing the mixing of the two electrolytic solutions 6 and 8 and a selective electrochemical barrier with respect to the ions to be separated.
- the electrolytic solution 8 of the cathode compartment does not become contaminated with impurities and elements more electropositive than zinc which lower the hydrogenated overvoltage.
- Another remarkable feature of the electrolysis cell according to the invention is its possibility of also and elegantly carrying out an electrorefining of the zi or of any other element exhibiting analogous properties.
- Any impurities in the electrolytic bath dissolve in the mercury at the same time as the zinc, since they are more electropositive than the latter and can be amalgamated with the mercury.
- the impurities precipitate in the form of sludge or remain in solution without interfering: this is the case with aluminum for example.
- the selective properties of the bipolar mercury electrode therefore explain that the electrolysis cell according to the invention allows the electro-refining of zinc.
- the mercury charged with amalgamated impurities can be regenerated continuously, for example by electrolysis in an auxiliary cell, in order to extract the amalgamated elements therefrom before being recycled.
- the electrodes can be connected to the positive and negative poles of the same electric voltage source.
- the two compartments can however also be connected to different sources of electrical potential, which makes it possible to separately regulate the operation of the two reactions in the anode and cathode compartments, the electrochemical yields of the two reactions not generally being equal.
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- Engineering & Computer Science (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
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Abstract
In an electrolysis cell (10) comprising two compartments (1, 2) which contain each a different electrolyte (6, 8) and of which the bottom is covered with a mercury sheet (5) acting as a bipolar electrode, the zinc of the zinc-bearing waste imersed in the electrolyte of the first compartment (1) is cathodically deposited on the mercury (5) to form a zinc amalgam. The zinc of said amalgam is then anodically redissolved in the second compartment (2) to reduce a cathodic deposit of pure zinc. The bipolar mercury electrode is used both as a mechanical barrier between the electrolytes and as an electrochemical barrier with respect to the ions to be separated and to the solvent, the electrolyte (8) of the second compartment (2) being thus preserved against any contamination by impurities.
Description
Procédé et appareil pour la récupération du zinc de déchets zincifères industriels Method and apparatus for recovering zinc from industrial zinciferous waste
La présente invention concerne une technique industriell pour la récupération du zinc et éventuellement d'autres composants ou constituants de déchets zincifères indus¬ triels, par exemple l'acier. Par déchet zincifère on entend ici tout produit résiduaire industriel ou solutio obtenue à partir de résidus industriels.The present invention relates to an industrial technique for the recovery of zinc and possibly other components or constituents of industrial zinciferous waste, for example steel. By zinciferous waste is meant here any industrial residual product or solutio obtained from industrial residues.
La récupération du zinc sous une forme valorisable revêt un intérêt économique considérable pour l'industrie en raison de la plus-value importante qu'elle confère aux déchets zincifères industriels, par exemple de l'industr sidérurgique et des tôleries. Si l'on considère par exemple les industries en aval des unités sidérurgiques, on note que la récupération du zinc des déchets de tôles galvanisées est intéressante car le recyclage de -ces déchets vers les unités sidérurgiques sans traitement préalable entraîne des inconvénients que l'on peut résum comme suit : les réfractaires des convertisseurs sont attaqués par le zinc et son oxyde et d'autre parties poussières recueillies dans les hottes et recyclées vers le haut-fourneau sont contaminées par l'oxyde de zinc qu attaque les réfractaires avec accumulation de dépôts qui perturbent le fonctionnement de l'ensemble. Par ailleurs ces déchets peuvent être valorisés si l'on en récupère le zinc qui est un élément précieux. Une récupération ratio nelle du zinc des déchets galvanisés permettrait enfin de
séparer les deux constituants : acier et zinc, et de les valoriser séparément.The recovery of zinc in a recoverable form is of considerable economic interest for the industry because of the significant added value that it gives to industrial zinciferous waste, for example from the steel industry and sheet metal works. If we consider, for example, the industries downstream of the steel units, we note that the recovery of zinc from the waste of galvanized sheet is interesting because the recycling of this waste to the steel units without prior treatment involves drawbacks that can be summarized as follows: the refractories of the converters are attacked by zinc and its oxide and other dust parts collected in the hoods and recycled to the blast furnace are contaminated by zinc oxide which attacks the refractories with accumulation of deposits which disrupt the functioning of the whole. In addition, this waste can be recovered if zinc is recovered, which is a precious element. A ratio recovery of zinc from galvanized waste would finally allow separate the two constituents: steel and zinc, and recover them separately.
Le traitement vers lequel on se tourne d'instinct lors- qu'il s'agit de dégalvaniser l'acier est la dissolution zinc dans un milieu acide. Cette technique est toutefoi loin d'être satisfaisante car si elle débarrasse bien l'acier de son revêtement gênant et le rend ainsi apte à un recyclage en aciérie, elle s'accompagne par contre de l'obligation de se débarrasser de solutions acides charg de sels de zinc et de fer. Un traitement de neutralisat de ces solutions est par' conséquent nécessaire, par exem à l'aide de chaux, pour permettre le rejet des eaux rési duaires. On note à ce sujet que l'acide utilisé pour la dissolution ne se trouve pas régénéré et qu'en outre un traitement de neutralisation donne lieu à la formation d boues difficilement valorisables sans un traitement coût du fait de la présence du zinc. De plus, le traitement neutralisation doit faire l'objet d'un contrôle soigné p éviter de rejeter en rivière des sels de zinc.The treatment to which we turn instinctively when it comes to degalvanizing steel is zinc dissolution in an acid medium. This technique is far from being satisfactory because if it rids the steel well of its annoying coating and thus makes it suitable for recycling in steelworks, it is accompanied by the obligation to get rid of acid solutions loaded with zinc and iron salts. A treatment of these solutions neutralisat is necessary therefore for exam with lime, to allow the discharge of resident duaires waters. It should be noted in this regard that the acid used for the dissolution is not regenerated and that, moreover, a neutralization treatment gives rise to the formation of sludges which are difficult to recover without a cost treatment due to the presence of zinc. In addition, the neutralization treatment must be carefully monitored to avoid dumping zinc salts into the river.
On ourrait également envisager un procédé de récupérati par électrolyse en milieu acide, des solutions de décapa des tôles galvanisées, ce qui permettrait d'obtenir immé diatement un dépôt cathodique de zinc micro-cristallin compact et aisément fusible. On pourrait dans ce cas . utiliser une cellule d' lectrolyse classique comme cela est pratiqué traditionnellement dans l'électro-métallurg du zinc. Toutefois, à la cathode apparaît une surtensio hydrogénée due au dégagement d'hydrogène, qui pourrait rendre le dépôt de zinc sur la cathode extrêmement dif¬ ficile sans une purification très poussée des solutions soumises à l'électrolyse afin d'-ên éliminer dans toute l mesure du possible tous les éléments qui abaissent cett surtension. D'autre part, dans cette hypothèse on se
trouverait confronté à des difficultés considérables du fait de la contamination des solutions par les sels de f A titre indicatif, on peut signaler que les solutions destinées à l'électrolyse du zinc doivent avoir une tene maximale en fer de 0 mg/1. Pour limiter l'attaque du fe le décapage acide des tôles galvanisées devrait être conduit dans des conditions très strictes et nécessiter l'emploi d'inhibiteurs de corrosion coûteux. Le décapag alcalin dont il sera question plus loin ne donne pas lie aux inconvénients précités.We could also envisage a process of recovery by electrolysis in an acid medium, of decapa solutions of galvanized sheets, which would allow to immediately obtain a cathodic deposit of compact and easily fusible micro-crystalline zinc. We could in this case. use a conventional electrolysis cell as is traditionally practiced in the electro-metallurgy of zinc. However, at the cathode appears a hydrogenated surge due to the evolution of hydrogen, which could make the deposit of zinc on the cathode extremely difficult without very thorough purification of the solutions subjected to electrolysis in order to be eliminated in any l as far as possible all the elements which lower this overvoltage. On the other hand, in this hypothesis we are would find it facing considerable difficulties due to the contamination of the solutions with the salts of f. As an indication, it may be pointed out that the solutions intended for the electrolysis of zinc must have a maximum iron content of 0 mg / l. To limit the attack of the Fe, the acid pickling of galvanized sheets should be carried out under very strict conditions and require the use of expensive corrosion inhibitors. The alkaline pickling which will be discussed below does not give rise to the aforementioned drawbacks.
En résumé, aucune des techniques connues ne permet de traiter les résidus industriels de façon économique afin d'en récupérer le zinc sous une forme directement valori sable industriellement.In summary, none of the known techniques makes it possible to treat industrial residues economically in order to recover the zinc in a form directly recoverable industrially.
L'invention apporte une solution industrielle attrayante qui comble cette lacune grâce à un procédé caractérisé e ce qu'on plonge les déchets zincifères dans une première solution, de préférence alcaline, en présence d'une napp de mercure et d'une électrode reliée électriquement à un potentiel électrique positif puis, par électrolyse, on dépose cathodiquementle zinc des déchets zincifères pour former un amalgame de zinc. On sépare ensuite l'amalgam de zinc de la première solution et on met 1'amalgame de zinc en contact avec une seconde solution acide, neutre ou complexante en présence d'une cathode connectée élec¬ triquement à un potentiel électrique négatif. Par électrolyse, on redissout alors anodiquement le zinc de 1'amalgame pour produire un dépôt de zinc pur sur la cathode.The invention provides an attractive industrial solution which fills this gap by means of a process characterized in that the zinciferous waste is immersed in a first solution, preferably alkaline, in the presence of a sheet of mercury and an electrically connected electrode. at a positive electrical potential then, by electrolysis, zinc is deposited cathodically from the zinciferous waste to form a zinc amalgam. The zinc amalgam is then separated from the first solution and the zinc amalgam is brought into contact with a second acidic, neutral or complexing solution in the presence of a cathode electrically connected to a negative electrical potential. By electrolysis, the zinc of the amalgam is then redissolved anodically to produce a deposit of pure zinc on the cathode.
Ce procédé selon l'invention est avantageusement mis en oeuvre dans une cellule d'électrolyse comprenant une cuve caractérisée par deux compartiments séparés par une clois
- h -This method according to the invention is advantageously implemented in an electrolysis cell comprising a cell characterized by two compartments separated by a partition - h -
et communiquant entre eux par une ouverture ménagée à la partie inférieure de la cloison, le fond de la cuve étan couvert d'une nappe de mercure en circulation forcée,qui s'étend dans le fond des deux'compartiments à travers l1 ouverture précitée, le premier compartiment contenant un premier electrolyte dans lequel est plongée une électrode reliée électriquement à un potentiel électrique positif, le second compartiment contenant un second electrolyte dans lequel est plongée une. cathode reliée à un potentiel électrique négatif, la nappe de mercure constituant à la fois une barrière mécanique pour éviter le mélange des deux électrolytes et une barrière électrochimique sélec¬ tive vis-à-vis des ions à séparer. L'électrolyte conten dans le compartiment anodique est, sans que ce facteur soit limitatif, de préférence une solution alcaline, par exemple une solution de NaOH, et l'électrolyte contenu dans le compartiment cathodique est une solution acide, neutre ou complexante, par exemple une solution de sulfa de zinc ou un bain de galvanisation électrolytique. Les électrodes peuvent être connectées électrique. ment aux pôles d'une même source de tension électrique ou à des sources de tension électrique distinctes.and communicating with each other through an opening in the lower part of the partition, the bottom of the tank etan covered with a layer of mercury in forced circulation, extending in the bottom of the two 'compartment through the aforementioned opening 1 , the first compartment containing a first electrolyte in which is immersed an electrode electrically connected to a positive electrical potential, the second compartment containing a second electrolyte in which is immersed one. cathode connected to a negative electrical potential, the sheet of mercury constituting both a mechanical barrier to avoid mixing of the two electrolytes and a selective electrochemical barrier vis-à-vis the ions to be separated. The electrolyte contained in the anode compartment is, without this factor being limiting, preferably an alkaline solution, for example a solution of NaOH, and the electrolyte contained in the cathode compartment is an acidic, neutral or complexing solution, for example a zinc sulfa solution or an electroplating bath. The electrodes can be connected electrically. ment to the poles of the same source of electrical voltage or to separate sources of electrical voltage.
La technique selon l'invention permet une récupération aisée du zinc et de l'acier des déchets de tôles galva¬ nisées avec notamment les avantages suivants : a. Les réactions de dissolution et d' lectrolyse se réalisent avec un rendement très élevé à la températu ordinaire et avec une faible consommation d'énergie. b. Le matériel requis est très simple. c. La consommation en réactifs est très faible puisqu'on doit simplement compenser les pertes dues à la présen d'impuretés éventuelles (par exemple solubillsation d traces d'aluminium). - d. Le zinc est obtenu sous forme mono-cristalline compac
stable, aisément fusible et valoriεable. On peut éga¬ lement le récupérer, dans une des variantes du procéd sous forme d'un revêtement de tôles d'acier (zingage électrolytique). 5 e. L'acier débarrassé du zinc peut être recyclé en aciér sans problèmes, f. Absence de tout problème de rejet d'eaux résiduaires de gaz ou poussières polluants .The technique according to the invention allows easy recovery of zinc and steel from galvanized sheet waste with in particular the following advantages: a. The dissolution and electrolysis reactions are carried out with a very high yield at ordinary temperature and with low energy consumption. b. The equipment required is very simple. vs. The consumption of reagents is very low since we simply have to compensate for the losses due to the presence of possible impurities (for example solubillation of traces of aluminum). - d. Zinc is obtained in compact mono-crystalline form stable, easily fusible and valuable. It can also be recovered in one of the variants of the procedure in the form of a coating of steel sheets (electrolytic zinc coating). 5 e. Steel free of zinc can be recycled into steel without problems, f. Absence of any problem of discharge of polluting waste gases or dust.
0 La technique selon l'invention permet également la produ tion de zinc pur valorisable par récupération de déchets zincifères industriels divers : poussières résiduaires d'aciéries électriques (qui contiennent des teneurs appr ciables de zinc pouvant atteindre 20 % et davantage) , 5 poussières résiduaires de hauts-fourneaux, attes de gal vanisation et même minerais de zinc lixiviés à la soude. Cette technique confère ainsi une plus-value importante tous ces déchets résiduaires.0 The technique according to the invention also allows the production of pure zinc recoverable by recovery of various industrial zinciferous waste: residual dust from electrical steelworks (which contain appreciable zinc contents of up to 20% and more), 5 residual dust blast furnaces, galvation attes and even zinc ores leached with soda. This technique thus gives significant added value to all this residual waste.
0 Un avantage supplémentaire de la cellule d' lectrolyse selon l'invention est qu'elle permet de réaliser en une seule opération à la fois la récupération électrolytique et l'électro-raffinage du zinc.0 An additional advantage of the electrolysis cell according to the invention is that it allows both electrolytic recovery and electro-refining of zinc to be carried out in a single operation.
^ De plus, cette cellule permet de réaliser des chaînes de galvanisation capables de travailler avec des matières d départ de faible coût, ce qui procure de substantielles économies de matières premières.^ In addition, this cell makes it possible to produce galvanizing chains capable of working with low-cost starting materials, which provides substantial savings in raw materials.
0 L'invention est exposée dans ce qui suit sur un exemple de réalisation illustré sur les dessins ci-annexés. Sur ces dessins :0 The invention is set out in the following on an exemplary embodiment illustrated in the accompanying drawings. In these drawings:
. la figure 1 est une vue en coupe transversale d'un exemple de cellule selon l'invention. . la figure 2 est une vue de dessus de la cellule de la figure 1.. Figure 1 is a cross-sectional view of an example cell according to the invention. . Figure 2 is a top view of the cell of Figure 1.
Les déchets zincifères à traiter sont plongés dans l'éle trolyte 6 du compartiment anodique 1. Les déchets sont soit directements des déchets métalliques (tôles galvani nisées, màttes de galvanisation) soit-une solution*zinci- fère obtenue par traitement.chimique de poussières d'aci ries, boues de hauts-fourneaux ou minerais de zinc par" exemple. Dans,,1e compartiment 1 la nappe de mercure 5 fonctionne comme cathode. Lorsque la tension électrique
est appliquée à la cellule, le zinc se dépose cathodique ent et s'amalgame avec le mercure. La nature de la réac tion anodique dans le compartiment 1 peut être sélection née judicieusement par l'agencement de ce compartiment e 5 fonction de la nature des déchets à traiter. Dans le cas de déchets de tôles galvanisées ou de mattes de galvani¬ sation, on choisit par exemple une électrode anodique en acier plongeant dans une solution de NaOH. Il se produit alors une dissolution électrochimique du zinc dans l'éle 10 trolyte. Dans le cas de solutions zincifères obtenues à partir dé poussières d'aciéries, de boues de hauts-four¬ neaux ou de minerais de zinc par exemple, la réaction anodique provoque un dégagement d'oxygène.The zinciferous waste to be treated is immersed in the trolyte ele 6 of the anode compartment 1. The waste is either directly metallic waste (galvanized sheets, galvanizing rods) or -a zinciferous solution obtained by chemical treatment of dust. aci ries, blast furnace sludge or zinc ores by "example. ,, in the first compartment 1 the mercury pool 5 operates as the cathode. When the voltage is applied to the cell, zinc is deposited cathodically and amalgamates with mercury. The nature of the anodic reaction in compartment 1 can be judiciously selected by the arrangement of this compartment 5 depending on the nature of the waste to be treated. In the case of waste galvanized sheet or galvanized matting, for example, an anodic steel electrode is chosen, immersed in a NaOH solution. Electrochemical dissolution of the zinc then takes place in the trolyte ele. In the case of zinciferous solutions obtained from steelworks dust, blast furnace sludge or zinc ores for example, the anodic reaction causes oxygen to be released.
15 Lorsqu'on utilise comme electrolyte du compartiment ano¬ dique 1 une solution de zincate de soude, la solution ser renouvelée en continu par apport d'électrolyte frais. Si pour l'électrolyte du compartiment anodique 1 on choisit une solution alcaline, on obtient une dissolutio15 When using as the electrolyte compartment ano ¬ dique January 1 zincate solution of sodium hydroxide, the solution ser renewed continuously by supplying fresh electrolyte. If for the electrolyte of the anode compartment 1 an alkaline solution is chosen, a dissolutio is obtained
20 sélective du zinc par rapport au fer et aux autres impu¬ retés contenues dans les déchets zincifères traités. On élimine ainsi la dissolution d'éléments indésirables peu ou pas solubles en milieu alcalin (par exemple le fe le cuivre...), ce qui permet de récupérer de façon ren-20 selective for zinc compared to iron and other impurities contained in the treated zinciferous waste. This eliminates the dissolution of undesirable elements that are sparingly or not soluble in an alkaline medium (for example, copper, etc.), which makes it possible to recover in a
25. table le zinc de résidus industriels tels que poussières d'aciéries, boues de hauts-fourneaux, mattes de galvani¬ sation, déchets de tôles galvanisées par exemple. De plus, l'électrolyse en milieu alcalin permet d'élimine les problèmes liés au dégagement d'hydrogène qui ne se 0 manifeste pas avec la même acuité qu'en milieu acide par suite du pH élevé.25. Table the zinc of industrial residues such as steelworks dust, blast furnace sludge, galvanizing mattes, galvanized sheet waste for example. In addition, electrolysis in an alkaline medium makes it possible to eliminate the problems associated with the evolution of hydrogen which does not manifest itself with the same acuity as in an acid medium due to the high pH.
L'amalgame de zinc formé dans le compartiment 1 passe dans le compartiment cathodique 2 avec la .nappe de mercur 5 5 en circulation. Le compartiment 2 contient un electroly propre qui consiste en une solution' acide, neutreThe zinc amalgam formed in compartment 1 passes into cathode compartment 2 with the mercurial blanket 5 5 in circulation. The compartment 2 contains a proper electrolytic consisting of a solution of acid, neutral
θMP
complexante selon les applications. Dans cet electrolyt est plongée une cathode 9 reliée électriquement à un pot tiel électrique négatif -V. L'électrolyte 8 est par exe pie une solution de sulfate de zinc dans laquelle plonge une cathode d'aluminium. Le zinc de l'amalgame ée redis sout anodiquement dans l'électrolyte 8 et le zinc dissou se dépose sur la cathode 9 sous une forme mono-cristalli pure, stable et non oxydable, qui présente une valeur ma chande intéressante.θMP complexing according to the applications. In this electrolyt is immersed a cathode 9 electrically connected to a negative electric pot -V. The electrolyte 8 is for example a solution of zinc sulfate in which an aluminum cathode is immersed. The zinc of the amalgam ée redis anodically sustained in the electrolyte 8 and the dissolved zinc is deposited on the cathode 9 in a pure, stable and non-oxidizable mono-crystalline form, which has an interesting value.
Le compartiment cathodique peut également' constituer un compartiment de galvanisation électrolytique. Pour ce faire, on choisit pour electrolyte un bain de galvanisat (bain cyanure alcalin ou bain acide par exemple) et on utilise le support d'.acier à galvaniser comme cathode. zinc se dépose alors directement sur l'acier sous forme d'un revêtement de galvanisation. La cellule d'électrol selon l'invention permet ainsi de constituer un poste de galvanisation directe particulièrement économique grâce l'utilisation de zinc récupéré à partir de déchets zinci fères. A noter que la cellule d'électrolyse élimine la présence de boues dans le compartiment cathodique.The cathode compartment may also 'be an electrolytic galvanizing compartment. To do this, an electroplating bath is chosen for the electrolyte (alkaline cyanide bath or acid bath for example) and the support of the steel to be galvanized is used as the cathode. zinc is then deposited directly on the steel in the form of a galvanizing coating. The electrolytic cell according to the invention thus makes it possible to constitute a particularly economical direct galvanizing station thanks to the use of zinc recovered from zinciferous waste. Note that the electrolysis cell eliminates the presence of sludge in the cathode compartment.
Une particularité remarquable de la cellule d' lectrolys selon l'invention est que la nappe de mercure 5 joue le rôle d'une électrode bipolaire qui est perméable aux élé ments amalgamables tels que zinc, plomb, bismuth, étain par exemple contenus dans le compartiment anodique 1 et qui est imperméable aux ions et au . solvant . La nappe mercure constitue ainsi à la fois une barrière mécanique empêchant le mélange des deux solutions électrolytiques 6 et 8 et une barrière électrochimique sélective vis-à-v des ions à séparer. Il en résulte que la solution élec¬ trolytique 8 du compartiment cathodique ne se contamine pas en impuretés et éléments plus électropositifε que le zinc qui abaissent la surtension hydrogénée.
En choisissant judicieusement le milieu électrolytique d compartiment cathodique on évite le dégagement d'hydrogè gênant.A remarkable feature of the lectrolys cell according to the invention is that the sheet of mercury 5 plays the role of a bipolar electrode which is permeable to amalgamable elements such as zinc, lead, bismuth, tin for example contained in the compartment anode 1 and which is impermeable to ions and. solvent. The mercury sheet thus constitutes both a mechanical barrier preventing the mixing of the two electrolytic solutions 6 and 8 and a selective electrochemical barrier with respect to the ions to be separated. As a result, the electrolytic solution 8 of the cathode compartment does not become contaminated with impurities and elements more electropositive than zinc which lower the hydrogenated overvoltage. By judiciously choosing the electrolytic medium of the cathode compartment, the annoying hydrogen release is avoided.
Une autre particularité remarquable de la cellule d' lec trolyse selon l'invention est sa possibilité de réaliser également et de façon élégante un électroraffinage du zi ou de tout autre élément présentant des propriétés analo gues. Les impuretés éventuelles du bain électrolytique dissolvent dans le mercure en même temps que le zinc pou qu'elles soient plus électropositives que celui-ci et qu'elles soient amalgamables avec le mercure. Dans le c contraire, les impuretés précipitent sous forme de boues ou restent en solution sans gêner : c'est le cas de l'al minium par exemple. En maintenant le potentiel du mercu à une valeur suffisamment négative pour que seul le zinc se redissolve, on élimine du compartiment cathodique tou les autres éléments indésirables plus électropositifs qu le zinc (par exemple le plomb). Les propriétés sélectiv de l'électrode bipolaire de mercure expliquent de la sor que la cellule d*électrolyse selon l'invention permet l'électro-raffinage du zinc. Le mercure chargé d'impure amalgamées peut être régénéré en continu, par exemple pa électrolyse dans une cellule auxiliaire, pour en extrair les éléments amalgamés avant d'être recyclé.Another remarkable feature of the electrolysis cell according to the invention is its possibility of also and elegantly carrying out an electrorefining of the zi or of any other element exhibiting analogous properties. Any impurities in the electrolytic bath dissolve in the mercury at the same time as the zinc, since they are more electropositive than the latter and can be amalgamated with the mercury. In the opposite case, the impurities precipitate in the form of sludge or remain in solution without interfering: this is the case with aluminum for example. By keeping the potential of mercu at a sufficiently negative value so that only zinc redissolves, all other undesirable elements more electropositive than zinc (for example lead) are eliminated from the cathode compartment. The selective properties of the bipolar mercury electrode therefore explain that the electrolysis cell according to the invention allows the electro-refining of zinc. The mercury charged with amalgamated impurities can be regenerated continuously, for example by electrolysis in an auxiliary cell, in order to extract the amalgamated elements therefrom before being recycled.
Les électrodes peuvent être connectées aux pôles positif et négatif d'une même source de tension électri¬ que. Les deux compartiments peuvent cependant être égale ment connectés à des sources de potentiel électrique différentes, ce qui permet de réguler séparément le fonc¬ tionnement des deux réactions dans les compartiments anodique et cathodique, les rendements électrochimiques des deux réactions n'étant généralement pas égaux. En outre, il est permis de choisir indépendamment les unes des autres la nature et la concentration de chaque compo¬ sant des électrolytes.
The electrodes can be connected to the positive and negative poles of the same electric voltage source. The two compartments can however also be connected to different sources of electrical potential, which makes it possible to separately regulate the operation of the two reactions in the anode and cathode compartments, the electrochemical yields of the two reactions not generally being equal. In addition, it is possible to independently choose from each other the nature and concentration of each component of the electrolytes.
Claims
1. Procédé de récupération du zinc contenu dans des déchets zincifères industriels, caractérisé en ce que on plonge les déchets zincifères dans une première solution électrolytique (6), de préférence alcaline, en présence d'une nappe de mercure (5) et d'une anode (7) connectée électriquement à un potentiel électrique positif, par électrolyse, on dépose cathodiquement le zinc des déchets zincifères pour former un amalgame de zinc, on sépare l'amalgame de zinc de ladite première solu¬ tion électrolytique (6), on met l'amalgame de zinc en contact avec une seconde solution électrolytique^ (8) en présence d'une cathode (9) connectée électriquement à un potentiel électrique négatif, et par électrolyse, on redissout anodiquement le zinc de l'amalgame pour produire un dépôt de zinc pur sur la cathode (9).1. A process for recovering the zinc contained in industrial zinciferous waste, characterized in that the zinciferous waste is immersed in a first electrolytic solution (6), preferably alkaline, in the presence of a sheet of mercury (5) and of an anode (7) electrically connected to a positive electrical potential, by electrolysis, the zinc is deposited cathodically from the zinciferous waste to form a zinc amalgam, the zinc amalgam is separated from said first electrolytic solution (6), puts the zinc amalgam in contact with a second electrolytic solution ^ (8) in the presence of a cathode (9) electrically connected to a negative electrical potential, and by electrolysis, the zinc of the amalgam is anodically redissolved to produce a deposit of pure zinc on the cathode (9).
2. Cellule d»électrolyse pour le traitement de déchets zincifères industriels, caractérisée par une cuve (10) comprenant deux compartiments (1, 2) séparés par une cloison (3) et communiquant entre eux par une ouverture (4) ménagée à la partie inférieure de la cloison, le fond de la cuve étant couvert d'une nappe de mercure (5) qui d'étend dans le fond des deux compartiments à travers l'ouverture précitée (4), le premier comparti¬ ment contenant une première solution électrolytique (6) dans laquelle est plongée une électrode (7) reliée élec- triquement à un potentiel électrique positif, le second compartiment contenant une seconde solution électroly¬ tique (8) dans laquelle est plongée une cathode (9) reliée électriquement à un potentiel électrique négatif, la nappe de mercure (5) constituant à la fois une barriè mécanique pour éviter le mélange des deux solutions électrolytiques (6, 8) et une barrière électrochimique sélective vis-à-vis des ions à séparer.2. Electrolysis cell for the treatment of industrial zinciferous waste, characterized by a tank (10) comprising two compartments (1, 2) separated by a partition (3) and communicating with each other by an opening (4) provided in the part bottom of the partition, the bottom of the tank being covered with a sheet of mercury (5) which extends into the bottom of the two compartments through the aforementioned opening (4), the first compartment containing a first solution electrolytic (6) in which is immersed an electrode (7) electrically connected to a positive electrical potential, the second compartment containing a second electrolytic solution (8) in which is immersed a cathode (9) electrically connected to a potential negative electric, the sheet of mercury (5) constituting both a barrier mechanical to avoid mixing of the two electrolytic solutions (6, 8) and a selective electrochemical barrier against the ions to be separated.
3. Cellule d'électrolyse selon la revendication 2, dans laquelle l'électrode anodique (7) porte les déchets zincifères à traiter.3. An electrolysis cell according to claim 2, in which the anode electrode (7) carries the zinciferous waste to be treated.
4. Cellule d'électrolyse selon la revendication 3, dans laquelle l'électrode anodique (7) est une chaîne trans¬ porteuse circulant dans là première solution électro¬ lytique (6) à une certaine distance au-dessus de la nappe de mercure (5).4. electrolysis cell according to claim 3, in which the anode electrode (7) is a carrier chain circulating in the first electro¬ lytic solution (6) at a certain distance above the sheet of mercury ( 5).
5. Cellule d'électrolyse selon la revendication 3, dans laquelle l'électrode anodique (7) est un panier tournant agencé pour plonger les déchets zincifères à traiter dans la première solution électrolytique (6).5. An electrolysis cell according to claim 3, in which the anode electrode (7) is a rotating basket arranged to immerse the zinc-bearing waste to be treated in the first electrolytic solution (6).
6. Cellule d'électrolyse selon l'une quelconque des revendications 2 à. 5 t dans laquelle la solution élec¬ trolytique (6) contenue dans le premier compartiment (1) est une solution alcaline.6. Electrolysis cell according to any one of claims 2 to. 5 t in which the electrolytic solution (6) contained in the first compartment (1) is an alkaline solution.
7. Cellule d'électrolyse selon l'une quelconque des revendications 2 à 6, dans laquelle "les électrodes .. (7 , 9) . sont connectées électriquement aux pôles d'une même source de tension électrique.7. Electrolysis cell according to any one of claims 2 to 6, in which " the electrodes .. (7, 9). Are electrically connected to the poles of the same source of electric voltage.
g# cellule d'électrolyse selon l'une quelconque des revendications 2 à 6, dans laquelle les électrodes (7 , 9) sont connectées électriquement à des sources de tension électrique distinctes.g # electrolysis cell according to any one of claims 2 to 6, in which the electrodes (7, 9) are electrically connected to separate electrical voltage sources.
_ OM _ OM
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| AT83901324T ATE25859T1 (en) | 1982-04-19 | 1983-04-15 | EQUIPMENT FOR CONTINUOUS PRODUCTION OF ELECTRICAL GALVANIZED SHEET METAL. |
| DE8383901324T DE3370166D1 (en) | 1982-04-19 | 1983-04-15 | Apparatus for continuous production of zinc electroplated sheet |
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| BE/207865 | 1982-04-19 | ||
| BE0/207865A BE892897A (en) | 1982-04-19 | 1982-04-19 | Recovering constituents of galvanised steel scrap - by electrolytic de-galvanising in alkaline electrolyte |
| BE210551 | 1983-04-14 | ||
| BE/210551830414 | 1983-04-14 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| WO1983003627A1 true WO1983003627A1 (en) | 1983-10-27 |
Family
ID=25653104
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| PCT/BE1983/000009 WO1983003627A1 (en) | 1982-04-19 | 1983-04-15 | Method and apparatus for reclaiming zinc from industrial zinc-bearing waste metal |
Country Status (5)
| Country | Link |
|---|---|
| EP (1) | EP0105896B1 (en) |
| JP (1) | JPS59500871A (en) |
| DE (1) | DE3370166D1 (en) |
| IT (1) | IT1194207B (en) |
| WO (1) | WO1983003627A1 (en) |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE746852C (en) * | 1940-04-04 | 1944-08-28 | Duisburger Kupferhuette | Process for processing zinc waste |
| DE1558763A1 (en) * | 1967-11-06 | 1970-07-16 | Schoelzel Dr Karl | Process for the electrochemical deposition of metals from solutions of their compounds |
| US4056450A (en) * | 1975-06-30 | 1977-11-01 | M & T Chemicals Inc. | Continuous detinning system |
| FR2397472A2 (en) * | 1977-07-13 | 1979-02-09 | Seprez | Zinc recovery from galvanising bath dross - which is dissolved electrolytically, followed by electrolytic winning of the zinc |
-
1983
- 1983-04-15 WO PCT/BE1983/000009 patent/WO1983003627A1/en active IP Right Grant
- 1983-04-15 DE DE8383901324T patent/DE3370166D1/en not_active Expired
- 1983-04-15 JP JP58501538A patent/JPS59500871A/en active Pending
- 1983-04-15 EP EP83901324A patent/EP0105896B1/en not_active Expired
- 1983-04-19 IT IT20679/83A patent/IT1194207B/en active
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE746852C (en) * | 1940-04-04 | 1944-08-28 | Duisburger Kupferhuette | Process for processing zinc waste |
| DE1558763A1 (en) * | 1967-11-06 | 1970-07-16 | Schoelzel Dr Karl | Process for the electrochemical deposition of metals from solutions of their compounds |
| US4056450A (en) * | 1975-06-30 | 1977-11-01 | M & T Chemicals Inc. | Continuous detinning system |
| FR2397472A2 (en) * | 1977-07-13 | 1979-02-09 | Seprez | Zinc recovery from galvanising bath dross - which is dissolved electrolytically, followed by electrolytic winning of the zinc |
Non-Patent Citations (1)
| Title |
|---|
| CHEMICAL ABSTRACTS, Volume 77, No. 10, 04 September 1972, Columbus, Ohio, (US) Won.H. LEE et al.: "Electrorefining of Zinc" see page 531, left hand column, Abstract 69255u, Kumsok Hakhoe Chi 1971, 9(3-4) 184-6(Concen) * |
Also Published As
| Publication number | Publication date |
|---|---|
| DE3370166D1 (en) | 1987-04-16 |
| IT1194207B (en) | 1988-09-14 |
| JPS59500871A (en) | 1984-05-17 |
| EP0105896B1 (en) | 1987-03-11 |
| EP0105896A1 (en) | 1984-04-25 |
| IT8320679A0 (en) | 1983-04-19 |
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