US3200055A - Process for the electrolytic production of hyperpure zinc - Google Patents

Process for the electrolytic production of hyperpure zinc Download PDF

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Publication number
US3200055A
US3200055A US121246A US12124661A US3200055A US 3200055 A US3200055 A US 3200055A US 121246 A US121246 A US 121246A US 12124661 A US12124661 A US 12124661A US 3200055 A US3200055 A US 3200055A
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Prior art keywords
lead
diaphragm
zinc
anode
electrolyte
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Expired - Lifetime
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US121246A
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English (en)
Inventor
Scacciati Giovanni
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MONTEVECCHIO ITALIANA DEL PIOMBO E DELLO ZINCO Soc
MONTEVECCHIO SOC IT DEL PIOMBO
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MONTEVECCHIO SOC IT DEL PIOMBO
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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

Definitions

  • diaphragms of various kinds into electrolysis cells had made it possible to obtain some improvements, but raised other difiiculties, whence the results obtained in practice could not be considered as conclusive and satisfactory.
  • the diaphragm was always intended only as a simple filtering means in order to prevent the electrolyte and therefore the cathodic zinc deposit from becoming contaminated by the slime formed on the anode and becoming detached therefrom.
  • the diaphragm had the task heretofore of mechanically preventing the passage of solid particles from the anodic zone to the cathodic zone while permitting passage of electrolyte and'current which is discharged onto the metal surface of the anode.
  • My invention has as an object the overcoming of these difficulties and the introduction of a completely different principle, namely the utilization of the diaphragm as a subsidiary anode on which part of the current is discharged; at the same time preventing transference of solution from the anodic to the cathodic zone, and thereby creating in the first zone conditions that renderthe solubility of PbSO to practically nil.
  • FIG. 1 is a vertical longitudinal section of an electrolytic cell
  • FIGS. 2 and 3 are vertical cross sections of a cathode and anode respectively;
  • FIG. 4 is a view of a preferred anode.
  • the lead anode is essentially limited to a current conductor while all the anodic phenomena are transferred to the subsidiary anode constituted by the unit: anolyte present between anode and diaphragm and surface of the diaphragm. More particularly, a manganese dioxide layer is caused to form on the fabric of the diaphragm. This manganese dioxide layer which appears to be electrically conductive, is charged positively like the lead anode and, therefore, acts not only as a diaphragm but also as a subsidiary anode.
  • the true anode is no longer constituted by the lead sheet as in normal electrolysis cells, but by the unit: lead sheet acting as a main conductor; highly acidic anolyte having a composition different from that of the remaining electrolyte which due: to its high acidity presents a very high electric conductivity; manganese-dioxide coated diaphragm which is also electrically conductive and on which all anodic phenomena (oxygen development, formation of peroxides, etc.) generally displayed by lead take place.
  • the anodic surface present in the electrolytic process proper for zinc production is now essentially a layer of manganese dioxide instead of a layer of lead dioxide as normally formed on a lead sheet.
  • the ideal conditions for reducing the formation of PbO to a substantial degree it has been found in fact that the formation of anode scales is reduced to a minimum) and the solubility of the Pb++ ions in the electrolyte of the cell is lowered to substantially zero.
  • the fabric should be capable of resisting a comparatively high acidity (up to 30% of H 50 and should have a very compact weft so as to be difiicultly permeable by the solution at the beginning of the electrolytic process.
  • the MnO layer which, as will be specified hereinafter, forms on the fabric, will then render the fabric practically impermeable to the electrolyte.
  • a fabric having the above characteristics and having proved to be the most suitable in our case is that constituted by very compact vinyl resin monofilament yarns (e.g., Vinyon or Movil), with a weight not lower than 400 g./m
  • the diaphragm fabric of the type and quality described under 1, and the surface of the metallic anode, the diaphragm is covered with an adherent and rather compact Mn0 layer within a comparatively short time, about 2 or 3 days of operation. It is known that the normal electrolyte for zinc contains in solution 1 to 5 g./l. of Mn++.
  • Manganese dioxide conducts electric current and, therefore, the current passing from the cathode to the anode in the cell is to a great extent discharged on the MnO surface formed.
  • a composite anode which in its innermost and more protected part is constituted by a normal lead-silver alloy, while its outer part is constituted by an electrically and chemically inert fabric and by an MnO layer on which most of the current is discharged, with a resulting lively oxygen development.
  • This layer obviously cannot yield any lead since it is lead-free.
  • the composite anode presents an intermediate anolyte layer of the high acidity, in which all lead compounds present, if any, are substantiallyinsoluble; t
  • the basic conditions for avoiding the transfer of lead in any form from the anode to the cathode and cathodic zinc deposits are obtained whereby the zinc deposited has a lead content less than ppm. and even less than 2-3 p.p.m., i.e., hyperpure Zinc with a purity higher than 99.999%.
  • the cell according to the present invention will, conveniently operate with comparatively low current density of from 200 to 250 amp/m and the temperature of the invention is represented, the same numerals in the various figures represent the same features.
  • A'indicates the feed of neutral electrolyte, B the discharge of acid electrolyte, 1 the anode, 2 the bag diaphragm, 3 the cathode, 4 the entire cell, 5 are U-shaped members hooked on the traverse 6 to hold the bag 2 in place.
  • manganese dioxide is made possible by the presence of manganese ions in the electrolyte used.
  • the purity attainable also depends on the purity of the neutral electrolyte fed, which should have a Cd content less than 0.0002 g. per liter and should be Pb-free.
  • the cells may be of conventional material but coated with lead-free antiacidmaterial, such as polyvinyl chloride.
  • the electrolyte should preferably be cooled to -35 C. by conventional means (not shown).
  • the lead sheets are of conventional lead, or lead alloy (e.g. with 1% Ag content).
  • a process for preparing hyperpure zinc containing less than 5 ppm. of lead, by electrolysis of a zinc sulfate solution containing manganous ions which comprises using an anode consisting of an insoluble lead-containing sheet, said lead sheet being surrounded by a compact diaphragm coated with manganese dioxide'and' having between said lead sheet and said diaphragm an anolyte containing about 250-280g/l. free H SO said manganese coating being formed by said electrolysis;
  • An electrolysis cell for producing zinc having a lead content less than 5 ppm. of lead, said cell having an anode comprising a lead silver alloy containing about 1% silver, said alloy acting as the main conductor, an anolyte having acidity of 250-280 g./l.
  • An electrolysis cell for producing zinc having a lead content less than 5 ppm. of lead, said cell having an anode comprising a lead silver alloy containing about 1% silver, said alloy acting as the main conductor, an anolyte having acidity of 250-280 g./l.
  • said diaphragm being made of synthetic fiber with a texture such that when used in an electrolytic process for producing zinc, anodic phenomena of the electrolytic process take place on said fabric diaphragm rather than on said lead anode surface, said diaphragm having a conductive'layer of manganese dioxide produced by oxidation of manganous ions present in the electrolyte, said diaphragm being held by mechanical means to said lead alloy.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Electrolytic Production Of Metals (AREA)
  • Electrolytic Production Of Non-Metals, Compounds, Apparatuses Therefor (AREA)
US121246A 1960-07-05 1961-06-30 Process for the electrolytic production of hyperpure zinc Expired - Lifetime US3200055A (en)

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IT1187260 1960-07-05

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US (1) US3200055A (fr)
BE (1) BE605729A (fr)
GB (1) GB914515A (fr)

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3620955A (en) * 1969-05-16 1971-11-16 Carrier Engineering Co Ltd Cathode cell
US4075069A (en) * 1975-04-10 1978-02-21 Mitsui Mining & Smelting Co., Ltd. Processes for preventing the generation of a mist of electrolyte and for recovering generated gases in electrowinning metal recovery, and electrodes for use in said processes
US4201653A (en) * 1977-10-11 1980-05-06 Inco Limited Electrowinning cell with bagged anode
US5431823A (en) * 1994-08-18 1995-07-11 Electric Fuel(E.F.L.) Ltd. Process for supporting and cleaning a mesh anode bag
US5498325A (en) * 1993-02-10 1996-03-12 Yamaha Corporation Method of electroplating
US20130319877A1 (en) * 2011-02-04 2013-12-05 Kcm '2000' Ad Method and device for zinc electrowinning from sulfate solutions
CN115747832A (zh) * 2022-11-01 2023-03-07 昆明理工大学 湿法炼锌含锰硫酸锌溶液一步净化除锰联产低铁锌的方法

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US757817A (en) * 1902-10-10 1904-04-19 Stanislaw Laszczynski Process of electrolytically extracting copper and zinc from ores.
US1299519A (en) * 1916-07-26 1919-04-08 Electrolytic Zinc Company Inc Method of handling anodes in electrolytic baths.
US2633452A (en) * 1950-05-03 1953-03-31 Jr George B Hogaboom Strainer bags for enclosing electroplating anodes
US2848399A (en) * 1955-06-06 1958-08-19 American Zinc Lead & Smelting Electrowinning of zinc
US2863810A (en) * 1957-03-26 1958-12-09 American Smelting Refining Process for electrowinning zinc
US2867570A (en) * 1954-10-14 1959-01-06 Cartoucherie Francaise Sa Devices for producing manganese dioxide by electrolysis

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US757817A (en) * 1902-10-10 1904-04-19 Stanislaw Laszczynski Process of electrolytically extracting copper and zinc from ores.
US1299519A (en) * 1916-07-26 1919-04-08 Electrolytic Zinc Company Inc Method of handling anodes in electrolytic baths.
US2633452A (en) * 1950-05-03 1953-03-31 Jr George B Hogaboom Strainer bags for enclosing electroplating anodes
US2867570A (en) * 1954-10-14 1959-01-06 Cartoucherie Francaise Sa Devices for producing manganese dioxide by electrolysis
US2848399A (en) * 1955-06-06 1958-08-19 American Zinc Lead & Smelting Electrowinning of zinc
US2863810A (en) * 1957-03-26 1958-12-09 American Smelting Refining Process for electrowinning zinc

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3620955A (en) * 1969-05-16 1971-11-16 Carrier Engineering Co Ltd Cathode cell
US4075069A (en) * 1975-04-10 1978-02-21 Mitsui Mining & Smelting Co., Ltd. Processes for preventing the generation of a mist of electrolyte and for recovering generated gases in electrowinning metal recovery, and electrodes for use in said processes
US4201653A (en) * 1977-10-11 1980-05-06 Inco Limited Electrowinning cell with bagged anode
US5498325A (en) * 1993-02-10 1996-03-12 Yamaha Corporation Method of electroplating
US5431823A (en) * 1994-08-18 1995-07-11 Electric Fuel(E.F.L.) Ltd. Process for supporting and cleaning a mesh anode bag
US20130319877A1 (en) * 2011-02-04 2013-12-05 Kcm '2000' Ad Method and device for zinc electrowinning from sulfate solutions
CN115747832A (zh) * 2022-11-01 2023-03-07 昆明理工大学 湿法炼锌含锰硫酸锌溶液一步净化除锰联产低铁锌的方法

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Publication number Publication date
BE605729A (fr) 1961-11-03
GB914515A (en) 1963-01-02

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