EP1483431B1 - Minimising carbon transfer in an electrolytic cell - Google Patents

Minimising carbon transfer in an electrolytic cell Download PDF

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Publication number
EP1483431B1
EP1483431B1 EP03743766A EP03743766A EP1483431B1 EP 1483431 B1 EP1483431 B1 EP 1483431B1 EP 03743766 A EP03743766 A EP 03743766A EP 03743766 A EP03743766 A EP 03743766A EP 1483431 B1 EP1483431 B1 EP 1483431B1
Authority
EP
European Patent Office
Prior art keywords
cell
cathode
potential
carbon
anode
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.)
Expired - Lifetime
Application number
EP03743766A
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German (de)
English (en)
French (fr)
Other versions
EP1483431A1 (en
EP1483431A4 (en
Inventor
Les Strezov
Ivan Ratchev
Steve Osborn
Sergey Alexander Bliznyukov
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.)
BHP Billiton Innovation Pty Ltd
Original Assignee
BHP Billiton Innovation Pty Ltd
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Filing date
Publication date
Application filed by BHP Billiton Innovation Pty Ltd filed Critical BHP Billiton Innovation Pty Ltd
Publication of EP1483431A1 publication Critical patent/EP1483431A1/en
Publication of EP1483431A4 publication Critical patent/EP1483431A4/en
Application granted granted Critical
Publication of EP1483431B1 publication Critical patent/EP1483431B1/en
Anticipated expiration legal-status Critical
Expired - Lifetime 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
    • C25C7/00—Constructional parts, or assemblies thereof, of cells; Servicing or operating of cells
    • C25C7/005—Constructional parts, or assemblies thereof, of cells; Servicing or operating of cells of cells for the electrolysis of melts
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B34/00—Obtaining refractory metals
    • C22B34/10—Obtaining titanium, zirconium or hafnium
    • C22B34/12—Obtaining titanium or titanium compounds from ores or scrap by metallurgical processing; preparation of titanium compounds from other titanium compounds see C01G23/00 - C01G23/08
    • C22B34/129—Obtaining titanium or titanium compounds from ores or scrap by metallurgical processing; preparation of titanium compounds from other titanium compounds see C01G23/00 - C01G23/08 obtaining metallic titanium from titanium compounds by dissociation, e.g. thermic dissociation of titanium tetraiodide, or by electrolysis or with the use of an electric arc

Definitions

  • the present invention relates to reduction of metal oxides in a solid state in an electrolytic cell.
  • the present invention was made during the course of an on-going research project on solid state reduction of titania (TiO 2 ) carried out by the applicant.
  • the CaCl 2 -based electrolyte was a commercially available source of CaCl 2 , namely calcium chloride dihydrate, that partially decomposed on heating and produced CaO.
  • the applicant operated the electrolytic cell at a potential above the decomposition potential of CaO and below the decomposition potential of CaCl 2 .
  • the experimental work was carried out using a CaCl 2 -based electrolyte at a cell potential below the decomposition potential of CaCl 2 .
  • the applicant believes that the initial deposition of Ca metal on the cathode was due to the presence of Ca ++ cations and O -- anions derived from CaO in the electrolyte.
  • the decomposition potential of CaO is less than the decomposition potential of CaCl 2 .
  • the-cell operation is dependent, at least during the early stages of cell operation, on decomposition of CaO, with Ca ++ cations migrating to the cathode and depositing as Ca metal and O -- anions migrating to the anode and forming CO and/or CO 2 (in a situation in which the anode is a graphite anode).
  • the applicant also believes that at later stages of the cell operation part of the Ca metal that deposited on the cathode was deposited directly on partially deoxidised titanium and thereafter participated in chemical reduction of titanium.
  • Carbon in the titanium is an undesirable contaminant.
  • carbon transfer was partially responsible for low energy efficiency of the cell. Both problems are significant barriers to commercialisation of electrolytic reduction technology.
  • the applicant carried out experimental work to identify the mechanism for carbon transfer and to determine how to minimise carbon transfer and/or to minimise the adverse effects of carbon transfer.
  • the present invention provides an electrolytic cell for reducing a metal oxide in a solid state, which electrolytic cell includes an anode formed from carbon, a cathode formed at least in part from the metal oxide, and a membrane that is permeable to oxygen anions and is impermeable to carbon in ionic and non-ionic forms positioned between the cathode and the anode to thereby prevent migration of carbon to the cathode.
  • the anode is formed from graphite.
  • the membrane may be formed from any suitable material.
  • the membrane is formed from a solid electrolyte.
  • One suitable solid electrolyte tested by the applicant is yttria stabilised zirconia.
  • the cathode also includes an electrical conductor.
  • the present invention also provides a method of reducing a metal oxide in a solid state using the above-described electrolytic cell.
  • the method includes a step of operating the cell at a potential that is above a decomposition potential of at least one of the constituents of the electrolyte so that there are cations of a metal other than that of the metal oxide in the electrolyte.
  • the metal oxide is a titanium oxide, such as titania
  • the electrolyte be a CaCl 2 -based electrolyte that includes CaO as one of constituents.
  • the cell potential be above the decomposition potential for CaO.
  • the cell potential be below the decomposition potential for CaCl 2 .
  • the cell potential be less than or equal to 3.0 V.
  • the cell potential be below 2.5 V.
  • the cell potential be below 2.0 V.
  • the cell potential be above 1.5 V.
  • the CaCl 2 -based electrolyte may be a commercially available source of CaCl 2 , such as calcium chloride dihydrate, that partially decomposes on heating and produces CaO or otherwise includes CaO.
  • the CaCl 2 -based electrolyte may include CaCl 2 and CaO that are added separately or pre-mixed to form the electrolyte.
  • the cell included a high density graphite crucible that formed the anode of the cell, a pool of molten CaCl 2 electrolyte in the crucible, and a cathode that included solid titania.
  • the solid titania was in the form of titania pellets connected to a lower end of a Kanthal or stainless steel electrically conductive wire.
  • the ionic barrier was in the form of a yttria stabilised zirconia membrane positioned between the anode and the cathode, thereby dividing the cell into an outer anode chamber and an inner cathode chamber.
  • Figure 1 is a schematic of the cell set-up for the experiment.
  • the cell included a graphite crucible 3 that formed the anode, a pool 19 of molten CaCl 2 electrolyte in the crucible, titania pellets 5 and an electrically conductive wire 7 that formed the cathode immersed in the electrolyte, and a yttria stabilised zirconia membrane 9 immersed in the electrolyte between the anode and the cathode.
  • the cell was located in a resistance furnace 11 heated to a temperature to maintain the electrolyte in a molten state.
  • the experimental set-up also included gas monitoring, cleaning, and analysis equipment.
  • the cell was operated at an applied potential of 3V for a period of 35 hours, during which time there was continuous monitoring of the off-gas from the furnace. At the conclusion of the experiment, the cell was cooled and the solidified electrolyte, the membrane, the anode and the cathode were analysed.
  • FIG. 2 is a summary of the results of the experiment.
  • Figure 2 shows measured voltage, current, CO and CO 2 composition of the off-gas for the experiment.
  • the invention is not so limited and extends to electrolytic reduction of other titanium oxides and to oxides of other metals and alloys.
  • Examples of other potentially important meals are aluminium, silicon, germanium, hafnium, magnesium, and molybdenum.
  • suitable electrolytes will be salts and oxides that are soluble in salts.
  • a potentially suitable electrolyte is BaCl 2 .

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Materials Engineering (AREA)
  • Environmental & Geological Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • Geology (AREA)
  • Manufacturing & Machinery (AREA)
  • Electrochemistry (AREA)
  • Electrolytic Production Of Metals (AREA)
  • Electrodes For Compound Or Non-Metal Manufacture (AREA)
  • Inert Electrodes (AREA)
  • Electrical Discharge Machining, Electrochemical Machining, And Combined Machining (AREA)
  • Battery Electrode And Active Subsutance (AREA)
  • Electrolytic Production Of Non-Metals, Compounds, Apparatuses Therefor (AREA)
EP03743766A 2002-03-13 2003-03-13 Minimising carbon transfer in an electrolytic cell Expired - Lifetime EP1483431B1 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
AUPS1170A AUPS117002A0 (en) 2002-03-13 2002-03-13 Minimising carbon transfer in an electrolytic cell
AUPS117002 2002-03-13
PCT/AU2003/000305 WO2003076692A1 (en) 2002-03-13 2003-03-13 Minimising carbon transfer in an electrolytic cell

Publications (3)

Publication Number Publication Date
EP1483431A1 EP1483431A1 (en) 2004-12-08
EP1483431A4 EP1483431A4 (en) 2006-06-28
EP1483431B1 true EP1483431B1 (en) 2007-07-18

Family

ID=3834768

Family Applications (1)

Application Number Title Priority Date Filing Date
EP03743766A Expired - Lifetime EP1483431B1 (en) 2002-03-13 2003-03-13 Minimising carbon transfer in an electrolytic cell

Country Status (12)

Country Link
US (1) US20050092129A1 (es)
EP (1) EP1483431B1 (es)
JP (1) JP2005520046A (es)
CN (1) CN1650052A (es)
AT (1) ATE367461T1 (es)
AU (1) AUPS117002A0 (es)
CA (1) CA2479050A1 (es)
DE (1) DE60314999D1 (es)
MX (1) MXPA04008886A (es)
RU (1) RU2302482C2 (es)
WO (1) WO2003076692A1 (es)
ZA (1) ZA200407433B (es)

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
AU2002951962A0 (en) * 2002-10-09 2002-10-24 Bhp Billiton Innovation Pty Ltd Electrolytic reduction of metal oxides
AU2002952083A0 (en) 2002-10-16 2002-10-31 Bhp Billiton Innovation Pty Ltd Minimising carbon transfer in an electrolytic cell
WO2006000025A1 (en) * 2004-06-28 2006-01-05 Bhp Billiton Innovation Pty Ltd Production of titanium
EA014138B1 (ru) * 2005-08-01 2010-10-29 БиЭйчПи БИЛЛИТОН ИННОВЕЙШН ПТИ ЛТД. Электрохимическое восстановление оксидов металлов
EP1982006A2 (en) * 2006-02-06 2008-10-22 E.I. Du Pont De Nemours And Company Method for electrolytic production of titanium and other metal powders

Family Cites Families (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH07113158B2 (ja) * 1984-04-14 1995-12-06 新日本製鐵株式会社 溶鋼の清浄化方法
JPH03115592A (ja) * 1989-09-28 1991-05-16 Osaka Titanium Co Ltd 溶融塩電解槽
US5670270A (en) * 1995-11-16 1997-09-23 The Dow Chemical Company Electrode structure for solid state electrochemical devices
GB9812169D0 (en) * 1998-06-05 1998-08-05 Univ Cambridge Tech Purification method
US6187168B1 (en) * 1998-10-06 2001-02-13 Aluminum Company Of America Electrolysis in a cell having a solid oxide ion conductor
GB2359564B (en) * 2000-02-22 2004-09-29 Secr Defence Improvements in the electrolytic reduction of metal oxides
ATE372395T1 (de) * 2000-02-22 2007-09-15 Metalysis Ltd Verfahren zur herstellung von metallschaum durch elektrolytische reduktion poröser oxidischer vorformen
US6540902B1 (en) * 2001-09-05 2003-04-01 The United States Of America As Represented By The United States Department Of Energy Direct electrochemical reduction of metal-oxides
JP4089944B2 (ja) * 2001-11-30 2008-05-28 財団法人電力中央研究所 電解還元装置および方法
WO2003076690A1 (en) * 2002-03-13 2003-09-18 Bhp Billiton Innovation Pty Ltd Reduction of metal oxides in an electrolytic cell
JP4252531B2 (ja) * 2004-12-15 2009-04-08 株式会社大阪チタニウムテクノロジーズ 金属製造方法

Also Published As

Publication number Publication date
RU2302482C2 (ru) 2007-07-10
CA2479050A1 (en) 2003-09-18
DE60314999D1 (de) 2007-08-30
EP1483431A1 (en) 2004-12-08
EP1483431A4 (en) 2006-06-28
MXPA04008886A (es) 2004-11-26
RU2004130453A (ru) 2005-06-10
ZA200407433B (en) 2005-10-10
ATE367461T1 (de) 2007-08-15
WO2003076692A1 (en) 2003-09-18
CN1650052A (zh) 2005-08-03
AUPS117002A0 (en) 2002-04-18
JP2005520046A (ja) 2005-07-07
US20050092129A1 (en) 2005-05-05

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