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WO2003048425A2 - Procede electrochimique de preparation de zinc metal - Google Patents

Procede electrochimique de preparation de zinc metal Download PDF

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Publication number
WO2003048425A2
WO2003048425A2 PCT/IB2002/005133 IB0205133W WO03048425A2 WO 2003048425 A2 WO2003048425 A2 WO 2003048425A2 IB 0205133 W IB0205133 W IB 0205133W WO 03048425 A2 WO03048425 A2 WO 03048425A2
Authority
WO
WIPO (PCT)
Prior art keywords
electrochemical process
zinc
electrochemical
zinc oxide
solution
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/IB2002/005133
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English (en)
Other versions
WO2003048425A3 (fr
Inventor
Baldev Kumar Bandlish
Vincent Wise Martin
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Clariant International Ltd
Original Assignee
Clariant International Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Clariant International Ltd filed Critical Clariant International Ltd
Priority to EP02785828A priority Critical patent/EP1458906A2/fr
Priority to AU2002351115A priority patent/AU2002351115A1/en
Publication of WO2003048425A2 publication Critical patent/WO2003048425A2/fr
Publication of WO2003048425A3 publication Critical patent/WO2003048425A3/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • 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
    • 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

  • the present invention provides an electrochemical process for the preparation of zinc metal.
  • Zinc powder is widely used in the chemical industry in various industries. Zinc oxide containing other zinc salts, metal impurities, etc. is produced as a byproduct. Recycling of the zinc oxide to produce pure zinc powder is highly desirable from a cost as well as an environmental point of view.
  • the electrodeposition of zinc metal is a well-known reaction in electrochemical technology (See, for example, D. Pletcher and F.C. Walsh, Industrial Electrochemistry, Blackie Academic, 1993).
  • the electrogalvanizing of steel is a process carried out on a very large scale and aqueous acid is the normal medium.
  • High speed, reel to reel galvanizing of steel is carried out in sulfuric acid with dimensionally stable anodes and uniform deposition is achieved at high current density by inducing very efficient mass transport by rapid movement of the steel surface.
  • the deposition of zinc metal is also the critical electrode reaction in the electrowinning and electrorefining of zinc.
  • Zinc metal can be produced by electrolysis either in strong alkaline or neutral zinc containing solutions.
  • the first patents obtained on the alkaline electrolysis process date back to the early thirties (German Patents, 581013, 506590, 653557). In these methods, a low current density of 1200-1500 amperes/sq. meter (Mm 2 ) was used. Volume efficiency and current density of these batch type processes are too low to be industrially attractive.
  • I. Orszagh and B. Vass Hung. J. Ind. Chem., 13, (1985) 287) used these methods to recycle zinc oxide byproduct from zinc dithionite production. There is at present a need to carry out an electrolysis reaction to produce zinc metal under conditions where corrosion of the electrodes is minimized.
  • the present invention fulfils this and other needs.
  • the present invention provides a low corrosion electrochemical process for preparing zinc metal wherein air or nitrogen is bubbled in during the electrochemical reduction process producing the zinc metal. It has been unexpectedly found that bubbling of air or nitrogen reduces electrode corrosion during the electrochemical process.
  • U.S. Patent No. 5,958,210 discloses a method for electrowinning metallic zinc from zinc ion in aqueous solution, said method comprising performing electrolysis on a mixture of solid conductive particles and aqueous alkali solution, said solution ranging in concentration from about 3N to about 20N alkali and containing dissolved zinc ion at an initial concentration ranging from about 50 to about 500 grams of zinc ion per liter of said solution, in an electrolytic cell containing first and second vertically arranged, parallel flat plates defined as a current feeder and a counter electrode, respectively, said counter electrode coated with a substance that is catalytic for oxygen evolution, said cell further containing an ion-permeable diaphragm parallel to each of said plates and interposed therebetween to define a gap between said current feeder and said diaphragm, by passing said mixture of particles and solution through said gap such that said particles contact said current feeder and passing a current across said gap, thereby depositing metallic zinc from said solution onto said particles.
  • U.S. Patent Application serial number 09/776,518 discloses an electrochemical process for preparing zinc powder which involves: a) providing to an electrochemical cell a basic solution of zinc oxide or any other zinc compound that reacts with an aqueous base to produce zinc oxide, the basic solution prepared by dissolving the zinc oxide or the other zinc compound in an aqueous 2.5 to 10.0 M base solution; and b) passing current to the cell at a current density of about 10,000 to about 40,000 A/m 2 for a time period sufficient to electrochemically reduce the zinc oxide to zinc powder, wherein the electrochemical process has a current efficiency of at least 70% and is substantially free from electrode corrosion.
  • U.S. Patent Application serial number 09/776,644 discloses a continuous electrochemical process for preparing zinc powder which involves: providing to an electrochemical cell a solution or suspension in an aqueous 1.25 Molar to 10.0 Molar base solution of zinc oxide or any other zinc compound that reacts with an aqueous base to produce zinc oxide, the solution or suspension containing at least 2 millimoles of solubilized zinc based species per 100 grams of electrolyte; and b) passing current to the cell at a current density of about 500 to 40,000 A/m 2 , for a time period sufficient to electrochemically reduce the solubilized zinc based species to zinc powder, while continuously or intermittently adding a sufficient amount of the zinc oxide or the other zinc compound to the cell to maintain the concentration of the solubilized zinc based species at a level of at least 2 millimoles per 100 grams of electrolyte and continuously or intermittently removing at least a portion of the zinc powder formed; wherein the electrolyte includes the aqueous 1.25 Molar to
  • the present invention provides a low corrosion electrochemical process for preparing zinc metal which comprises electrochemically reducing an aqueous basic solution or slurry of zinc oxide or any other zinc compound that reacts with an aqueous base to produce zinc oxide, wherein the electrochemical process is carried out in an undivided electrochemical cell, and wherein air or nitrogen is bubbled in through the solution or slurry of zinc oxide or said other zinc compound during said electrochemical process.
  • the present invention provides a low corrosion electrochemical process for preparing zinc metal which comprises electrochemically reducing an aqueous basic solution or slurry of zinc oxide or any other zinc compound (such as zinc sulfate) that reacts with an aqueous base to produce zinc oxide, wherein the electrochemical process is carried out in an undivided electrochemical cell, and wherein air or nitrogen is bubbled in through the solution or slurry of zinc oxide or said other zinc compound during said electrochemical process.
  • any other zinc compound such as zinc sulfate
  • the anode may be made from any conventional suitable material such as platinum, or iridium, either of which may be coated over an inert support such as niobium or titanium.
  • the anode may also be made of nickel, or from conventional materials having good alkali corrosion resistance, e.g., lead or stainless steel.
  • the cathode may be made from any conventional suitable materials having good alkali corrosion resistance, such as magnesium, magnesium alloy, copper, lead and stainless steel.
  • the anode in the present invention is formed of stainless steel or nickel and the cathode is formed of stainless steel, magnesium, magnesium alloy or copper.
  • the cathode and the anode are stainless steel and copper respectively, and in one embodiment nickel and copper respectively.
  • aqueous base solutions employed in the process of the invention are prepared by combining water with a source of alkali metal or alkaline earth metal ions, such as lithium, sodium, and potassium, and a source of hydroxyl (OH " ions).
  • a source of alkali metal or alkaline earth metal ions such as lithium, sodium, and potassium
  • OH " ions hydroxyl
  • a single source may of course provide both types of ions.
  • the various alkali or alkaline earth metal ions are preferably supplied from various compounds such as hydroxides and oxides.
  • Preferred base solutions are sodium and potassium hydroxide solutions.
  • temperatures higher than ambient are generally desired because of the beneficial effects on the kinetics of all steps in an electrode process.
  • the diffusion coefficient, the exchange current density and the rates of chemical reactions generally are increased.
  • the decrease in viscosity and increase in diffusion coefficient leads to the increased mass transport rates.
  • This increased mass transport of zinc ions from the bulk of the solution to the cathodic region is highly desirable.
  • increase in the rate of chemical reaction such as the oxidation of zinc produced with oxygen and mass transport of the byproduct oxygen to the bulk of the solution may not be desirable.
  • higher than ambient temperatures are found to be favorable for the electrolytic reduction of zinc oxide to zinc, and are preferred.
  • the presently claimed electrochemical reduction process is conducted at a temperature of from 10°C to 105°C, preferably from 40° to 80°C, and more preferably from 60° to 75°C.
  • the electrochemical process of the present invention is a continuous process.
  • continuous in the present context is well understood by one of ordinary skill in the art.
  • it relates a process wherein zinc oxide or the other zinc compound can be added continuously to the electrochemical cell and at least a portion of the zinc metal formed is removed continuously or intermittently during the electrochemical process.
  • a continuous electrochemical process has been disclosed in U.S. Application serial number 09/776,664 (filed February 2, 2001).
  • a resin Kettle (5 inch in diameter and 18 inch high) is used as the cell.
  • a solution or slurry of zinc oxide in the aqueous sodium hydroxide solution (3 to 3.5 liters) at 20 to 80°C is charged into the resin kettle.
  • a thermometer, desired cathodes and anodes are positioned in the cell using laboratory clamps. Mixing is achieved by bubbling air or nitrogen through the solution or slurry of ZnO. In some experiments mechanical stirring in addition to bubbling of air or nitrogen is used. Control experiments use only mechanical stirring for mixing (no air or nitrogen bubbling). Parts of the cathode and anode surfaces are covered with Teflon tape to achieve the desired active cathode and anode surface areas.
  • Electrolysis is carried out at a current density of about 5000 Amps/m 2 . A portion of the zinc deposited on the cathode is removed periodically. At the end of the experiment, zinc particles are separated from the electrolyte by decantation, washed with water and then dried. Dried zinc particles were analyzed to determine the zinc content.
  • All slurry based electrolysis contained undissolved ZnO in the electrolyte during the entire electrolysis.
  • Zn particles deposited on the copper cathode were easily removable.
  • the precision of the corrosion results is about ⁇ 1g/45.5 kg Zn (the values expressed in g/45.5 kg Zn are normalized values).

Landscapes

  • 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)
  • Preventing Corrosion Or Incrustation Of Metals (AREA)

Abstract

L'invention concerne un procédé électrochimique à faible corrosion destiné à préparer du zinc métal, consistant à réaliser une réduction électrochimique d'une solution aqueuse basique de zinc ou d'une suspension d'oxyde de zinc ou de tout composé de zinc réagissant avec une base aqueuse afin de donner de l'oxyde de zinc, ce procédé électrochimique étant mené dans une cellule électrochimique non divisée dans laquelle de l'air ou de l'azote est passé, sous forme de bulles, à travers la solution ou la suspension d'oxyde de zinc ou d'autre composé de zinc, durant le procédé électrochimique.
PCT/IB2002/005133 2001-12-07 2002-12-05 Procede electrochimique de preparation de zinc metal Ceased WO2003048425A2 (fr)

Priority Applications (2)

Application Number Priority Date Filing Date Title
EP02785828A EP1458906A2 (fr) 2001-12-07 2002-12-05 Procede electrochimique de preparation de zinc metal
AU2002351115A AU2002351115A1 (en) 2001-12-07 2002-12-05 Electrochemical process for preparation of zinc metal

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US10/015,185 US20030106806A1 (en) 2001-12-07 2001-12-07 Electrochemical process for preparation of zinc metal
US10/015,185 2001-12-07

Publications (2)

Publication Number Publication Date
WO2003048425A2 true WO2003048425A2 (fr) 2003-06-12
WO2003048425A3 WO2003048425A3 (fr) 2004-03-18

Family

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Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/IB2002/005133 Ceased WO2003048425A2 (fr) 2001-12-07 2002-12-05 Procede electrochimique de preparation de zinc metal

Country Status (4)

Country Link
US (1) US20030106806A1 (fr)
EP (1) EP1458906A2 (fr)
AU (1) AU2002351115A1 (fr)
WO (1) WO2003048425A2 (fr)

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8002872B2 (en) * 2005-11-22 2011-08-23 Carbontech, Llc Methods of recovering and purifying secondary aluminum
US8409419B2 (en) * 2008-05-21 2013-04-02 Paul R. Kruesi Conversion of carbon to hydrocarbons

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE653557C (de) * 1936-08-16 1937-11-27 I G Farbenindustrie Akt Ges Herstellung von Zinkstaub
DE4429195A1 (de) * 1994-08-18 1996-02-22 Dechema Verfahren zur elektrolytischen Zinkabscheidung aus alkalischen zyanidfreien Elektrolyten
DE4438692C2 (de) * 1994-10-29 2003-05-28 Outokumpu Oy Verfahren zur elektrochemischen Gewinnung der Metalle Kupfer, Zink, Blei, Nickel oder Kobalt
US20030183535A1 (en) * 2002-03-28 2003-10-02 Clariant International Ltd. Process for the preparation of zinc dithionite

Also Published As

Publication number Publication date
EP1458906A2 (fr) 2004-09-22
AU2002351115A8 (en) 2003-06-17
AU2002351115A1 (en) 2003-06-17
WO2003048425A3 (fr) 2004-03-18
US20030106806A1 (en) 2003-06-12

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