Classifications

• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25C—PROCESSES FOR THE ELECTROLYTIC PRODUCTION, RECOVERY OR REFINING OF METALS; APPARATUS THEREFOR
  • C25C3/00—Electrolytic production, recovery or refining of metals by electrolysis of melts
  • C25C3/26—Electrolytic production, recovery or refining of metals by electrolysis of melts of titanium, zirconium, hafnium, tantalum or vanadium
  • C25C3/28—Electrolytic production, recovery or refining of metals by electrolysis of melts of titanium, zirconium, hafnium, tantalum or vanadium of titanium
• • 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
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C14/00—Alloys based on titanium
• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25C—PROCESSES FOR THE ELECTROLYTIC PRODUCTION, RECOVERY OR REFINING OF METALS; APPARATUS THEREFOR
  • C25C3/00—Electrolytic production, recovery or refining of metals by electrolysis of melts

Definitions

• Titanium and its alloys exhibit excellent mechanical properties, unrivalled corrosion resistance and outstanding biocompatibility; however, annual global titanium production is dwarfed by commodity metals such as steel and aluminium.
• Kroll process One needs only to examine the complex and discontinuous production method, the Kroll process, to correlate the high price of titanium with its low consumption.
• alternate processing routes have been sought, in vain; titanium oxides are extremely stable compounds that are bound with increasing tenacity to oxygen as the latter concentration decreases.
• a high solubility for oxygen in metallic titanium necessitates carbo-chlorination of titanium dioxide to produce an oxygen-free, chloride feedstock (TiCI 4 ), which is subsequently metallothermically reduced with liquid magnesium.
• the present invention describes a process in which, a metal, M 1 , is produced in an electrolytic cell consisting of a molten electrolyte, M Z Y - M Z O, at least one anode and at least one cathode, characterised in that the passage of current between said anode(s) and cathode(s) through said electrolyte, produces a metal, M 1 , from a raw material, M 1 X, containing a non-metallic species, X, under conditions such that the potential at the cathode causes the reduction of the M z cation and the formation of M z at activities less than one.
• the M z produced in this manner reduces the raw material, M-
• the raw material feed may also contain both species M 1 and X, in a ternary or higher order oxide, of the form M 2 M 1 X, by way of example.
• E is measured in volts versus the standard state potential for the reduction of Ca 2+ to Ca 0
• R is the universal gas constant (8,3144 J-mol "1 -K "1)
• the melt contains neither calcium metal as a discrete phase nor the high concentrations of Ca 0 necessary to constitute a "strongly reducing molten salt".
• Operation of the electrolysis cell such that the cathode potential is less negative than that corresponding to saturated calcium formation, which results in the reduction of the electrolyte cation to produce calcium in the solvated state, is equally effective for reduction of the metal oxide.
• Figure 1 is a current versus potential plot of TiO 2 and Mo in CaCI 2 at 900 3 C.
• Figure 2 is a predominance diagram showing the conditions of electrode potential and melt oxide content corresponding to a given electrochemical reaction for a system with a CaCI 2 -CaO electrolyte and a graphite electrode(s).
• Figure 3 is a predominance diagram showing the conditions of electrode potential and melt oxide content corresponding to a given electrochemical reaction for a system with a CaCI 2 -CaO electrolyte, a graphite anode(s), and a cathode consisting of titanium oxide.
• FIG. 4 is a schematic diagram of the electrochemical cell used in conjunction with the present invention.
• Figure 5 is the x-ray diffraction pattern of cathode material produced after 24 hours with a cell voltage of 50OmV.
• Figure 6 is the x-ray diffraction pattern of cathode material produced after 24 hours with a cell voltage of 75OmV.
• Figure 7 is the x-ray diffraction pattern of cathode material produced after 24 hours with a cell voltage of 100OmV.
• Figure 8 is an optical image of partially reduced cathode material exhibiting a metallic shell and a core consisting of oxides.
• Figure 9 is a potential versus time plot for TiO 2 reduced under constant current
• FIG. 10 Scanning electron micrograph of Ti-10V-2Fe-3AI alloy produced via the present invention.
• Table 1 lists the standard state reduction potential for Ca 2+ to Ca 0 , and the potentials calculated from Equation 1 corresponding to selected dissolved activities of Ca 0 at 900 g C.
• a molten salt reactor depicted in Figure 4, was assembled using vertical tube furnace with temperatures recorded using a thermocouple (1 ) within the cell and a PC-based data acquisition unit.
• a sealed lnconel reaction (2) vessel housed alumina crucibles (3), which contained the CaCI 2 -CaO electrolyte (4). This electrolyte was obtained by mixing thermally dried CaCI 2 -2H 2 O and 1 wt% CaO, and was subsequently heated in the retort under flowing argon (5, 6) to 1173 K.
• Example 2 Reduction of TiO? under conditions of constantly high Ca activity
• the experimental apparatus used in Example 1 was reproduced identically, except for the electrolysis voltage, which was fixed at 3V, and the duration of electrolysis, which was 12 hours.
• the sample was removed from the electrolyte, allowed to cool, and washed in water.
• a cross section of the sample ( Figure 8) revealed a metallic ⁇ -titanium case that enclosed a darker powder, which was identified by x-ray diffraction as a titanium sub-oxide.
• the thickness of the metallic layer was approximately 100-200 microns, which effectively acted as a diffusion barrier preventing full reduction of the titanium dioxide pellet.
• Example 2 An identical reactor to that used in Example 1 was employed to reduce 10-micron thick TiO 2 layers thermally formed on a titanium substrate.
• a potentiostat was used in conjunction with a graphite counter electrode, nickel/nickel chloride reference electrode and TiO 2 working electrodes.
• a constant reduction current was applied to the working electrode and the potential, with respect to the reference electrode, was recorded over time ( Figure 9). The reduction current was terminated when the working electrode potential reached a steady state value that did not continue to decrease over a long period of time. Since the TiO 2 layer was of finite thickness, the reduction current at the conclusion of the experiment must have been comprised primarily of calcium formation.
• Example 4 Production of conventional titanium alloy (Ti-10V-2Fe-3AI) Reagent grade oxide powders from Alfa Aesar (TiO 2 99.5 %, FeTiO 3 99.8 %, AI 2 O 3 99.9 % and V 2 O 5 99 %, 1-2 ⁇ m particle size) were mixed, as-received, with a small amount of distilled water, which acted as a binding agent, to achieve a final composition of 10 wt% V, 2 wt% Fe, 3 wt% Al with the balance of titanium. The powder was then ground with a mortar and pestle for 5 minutes to break down large agglomerates prior to uniaxial compaction on a 15 mm diameter die at 100 MPa to obtain the desired preform shape.
• Alfa Aesar TiO 2 99.5 %, FeTiO 3 99.8 %, AI 2 O 3 99.9 % and V 2 O 5 99 %, 1-2 ⁇ m particle size

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• Chemical & Material Sciences (AREA)
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• Organic Chemistry (AREA)
• Materials Engineering (AREA)
• Metallurgy (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Mechanical Engineering (AREA)
• Electrochemistry (AREA)
• Life Sciences & Earth Sciences (AREA)
• Environmental & Geological Engineering (AREA)
• General Life Sciences & Earth Sciences (AREA)
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• Manufacturing & Machinery (AREA)
• Electrolytic Production Of Metals (AREA)

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• 2006
  • 2006-06-14 NO NO20062776A patent/NO20062776L/no not_active Application Discontinuation
• 2007
  • 2007-05-30 US US12/308,367 patent/US20100006448A1/en not_active Abandoned
  • 2007-05-30 WO PCT/NO2007/000183 patent/WO2007145526A1/en active Application Filing
  • 2007-05-30 EP EP07747642A patent/EP2032727A4/de not_active Withdrawn

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