1. 1 2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006 Iron Removal from Titanium Ore by Electrochemical Method Isao Obana 1 and Toru H. Okabe 2 1 Graduate School of Engineering, The University of Tokyo 2 International Research Center for Sustainable Materials, Institute of Industrial Science, The University of Tokyo

2. 2 2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006 Aircraft Spacecraft Chemical plants Implants Artificial bones, etc. Applications Lightweight and high strength Corrosion resistant Biocompatible Some titanium alloys ： shape memory effect superelasticity Introduction Ti ore + C + 2 Cl 2 → TiCl 4 (+ FeCl x ) + CO 2 Chlorination TiCl 4 + 2 Mg Reduction MgCl 2 Electrolysis The Kroll process: Currently employed Ti production process Mg & TiCl 4 Feed port Sponge Titanium → Ti + 2 MgCl 2 → Mg + Cl 2 Reaction Container MgCl 2 Features of titanium

3. 3 2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006 2. Chlorine circulation in the Kroll process can be improved. 3.This process can also be applied to the new Ti production processes, e.g., the direct electrochemical reduction of TiO 2. Upgrading Ti ore (CaCl 2 ) Ti ore (Ilmenite, FeTiO x )Upgraded Ilmenite (UGI) TiO x FeO x Others TiO x FeO x Others Upgrade Chloride wastes Discarded Ti metal Ti smelting Low grade Ti ore Upgraded Ti oreFeCl x (+AlCl 3 ) (FeTiO X ) (TiO 2 ) MCl x Chlorine recovery Selective chlorination Fe TiCl 4 Ti scrap Advantages: 1 ． Material cost can be reduced by using low-grade ore.

4. 4 2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006 Previous study Ref. R. Matsuoka and T. H. Okabe: Symposium on Metallurgical Technology for Waste Minimization at the 2005 TMS Annual Meeting, San Francisco, California (2005.2.13–17). The selective chlorination of Ti ore by MgCl 2 or CaCl 2 is found to be feasible. Pyrometallurgical de-Fe process FeO x ( s, in Ti ore) + MgCl 2 ( s, l ) → FeCl x ( l, g ) + MgO ( s ) CaCl 2 ( s, l ) + H 2 O ( g ) → HCl ( g ) + CaO ( s ) FeO x ( s, in Ti ore) + HCl ( g ) → FeCl x ( l, g ) + H 2 O ( g ) Susceptor RF coil Vacuum pump Quartz Tube Deposit Mixture of Ti ore and MCl x N 2 or N 2 +H 2 O gas Condenser (FeCl x ) T = 973~1373 K

5. 5 2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006 Study objectives 1. Thermodynamic analysis of selective chlorination 2. Fundamental experiments of selective chlorination by electrochemical methods 3. Reduction experiment for the sample obtained by selective chlorination Application of electrochemical method using molten salt Low-grade Ti ore TiO 2 + flux (FeTiO x ) Fe removal by selective chlorination Ti powder Direct reduction of TiO 2 obtained after Fe removal

6. 6 2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006 Fig. Chemical potential diagram for Fe-Cl-O and Ti-Cl-O systems at 1100 K The selective chlorination of Ti ore by controlling chlorine partial pressure may be possible using an electrochemical technique. Thermodynamic analysis (Ti ore chlorination) Ti ore : FeTi x O y For simplicity, it is assumed to be a mixture of TiO x and FeO x TiCl 4 ( g ) TiCl 3 ( s ) –40 –10 –30 –20 –50 –60 0 -40-10-30-200 CaO ( s )/CaCl 2 ( l ) eq. a CaO = 0.1 Fe-Cl-O and Ti-Cl-O system, T = 1100 K Potential region for selective chlorination of iron from titanium ore Potential region for chlorination of titanium Oxygen partial pressure, log p O 2 (atm) Chlorine partial pressure, log p Cl 2 (atm) C/CO eq. CO/CO 2 eq. H 2 O ( g )/HCl ( g ) eq. MgO ( g) /MgCl 2 ( l ) eq. TiCl 2 ( s ) FeO ( s ) Fe 2 O 3 ( s ) FeCl 2 ( l ) Fe 3 O 4 ( s ) FeCl 3 ( g )Fe ( s ) TiO ( s ) TiO 2 ( s ) Ti ( s ) TiO 2 → Stable FeO x → FeCl x ( g )

7. 7 2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006 2 Cl – (in CaCl 2 ) → Cl 2 + 2 e – Anode: Chlorine chemical potential in molten CaCl 2 at anode can be increased electrochemically. Cathode ： Ca 2+ + 2 e – → Ca Electrolysis Fe n+ + n e – → Fe FeO x + Cl 2 → FeCl x ↑ + O 2– e–e– Molten salt (CaCl 2, MgCl 2, etc.) DC power source Upgraded or low-grade Ti ore (e.g., FeTiO x ) FeCl 3, AlCl 3, O 2, CO 2 gas Chlorination by increasing Cl 2 potential

8. 8 2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006 Reactions CaCl 2 ( l ) = Ca ( l ) + Cl 2 ( g )6293.26 FeO ( s ) = Fe ( s ) + 1/2 O 2 ( g )2011.04 FeO ( s ) + 1/2 C ( s ) = Fe ( s ) + 1/2 CO 2 ( g )30.02 FeTiO 3 ( s ) + CaCl 2 ( l ) + 1/2 C ( s ) = TiO 2 ( s ) + FeCl 2 ( l ) + Ca ( l ) + 1/2 CO 2 ( g ) 4382.34 a: I. Barin: Thermochemical Data of Pure Substances, 3rd ed. (Weinheim, Federal Republic of Germany, VCH Verlagsgesellschaft mbH, 1997) FeO ( s ) + CaCl 2 ( l ) + C ( s ) = FeCl 2 ( l ) + CO ( g ) + Ca ( l )4092.23 Theoretical decomposition voltage Under a certain condition, the selective chlorination of Fe in Ti ore may proceed below the theoretical decomposition voltage of CaCl 2.  G o /kJ mol -1a  E o /V a Table Standard Gibbs energy of decomposition and theoretical voltage of that in several chemical species at 1100 K.

9. 9 2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006 Iron removal by selective chlorination using an electrochemical method Low-grade Ti ore TiO 2 + flux (FeTiO x ) Fe removal by selective chlorination Ti powder Direct reduction of TiO 2 obtained after Fe removal

10. 10 2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006 Experimental apparatus (a) Reaction chamber (b) Reaction cell Ceramic insulator Thermocouple Heater Rubber plug Ar inlet Wheel flange Stainless steel tube (Electrode) Molten salt (CaCl 2 ) Potential lead (Nickel wire) Mild steel crucible (Cathode) Graphite crucible (Anode) Sample V A Height 40 mm (a)(b) I.D. 17 mm O.D. 19 mm Surface of molten salt Support rod (Stainless steel tube) Sample (Ti ore, CaCl 2, etc.) Screw (Stainless steel) Graphite crucible Air hole Holes for molten salt diffusion

11. 11 2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006 Selective chlorination experiments Mass of sample i, w i /g Ti ore CaCl 2 Carbon powder 4.00 ーー A B C 0.74 2.17 ー 0.18 Voltage, E /V Time, t” /h 1.5 12 3 3 IlmeniteUGI D E 1.59 1.27 ー 1.5 2.0 3 3 ー ー ー ー ーー Experimental conditions ： Temperature: Atmosphere: Molten salt: Cathode: Anode: Exp. No. Sample Molten CaCl 2 Mild steel crucible (Cathode) Graphite crucible containing Ti ore (Anode) Voltage monitor /controller e–e– Low initial Fe content 1100 K Ar CaCl 2 (800 g) Mild steel crucible (I.D. 96 mm) Graphite crucible (I.D. 17 mm)

12. 12 2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006 Results of the selective chlorination experiments XRF analysis Fe/Ti ratio decreased from 114% to 7.2% (ilmenite) and from 2.00% to 0.18% (UGI). Table Analytical results of the samples obtained after electrochemical selective chlorination 0.295.91.90.1 2.00 94% of Fe in ilmenite and 92% of Fe in UGI were successfully removed. Exp. D0.598.00.20.10.30.18 Exp. E0.296.90.30.20.50.28 UGI 0.642.648.70.32.2114 Exp. A2.745.721.712.31.447.4 Exp. B0.447.23.447.90.07.2 Exp. C0.130.27.542.70.324.7 Ilmenite a: Average values of the samples obtained from the upper and lower parts of the graphite crucible Concentration of element i, C i (mass%) VTiFeCaSi Fe/Ti ratio, R Fe/Ti (%) Sample Exp. X0.145.15.840.60.512.9

13. 13 2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006 XRD analysis A mixture of CaTiO 3 and TiO 2 was obtained after Fe removal. Fig. XRD pattern of the start sample and the sample obtained after Fe removal (Exp. B) :CaTiO 3 :TiO 2 Angle, 2θ (degree) FeTiO 3 ( s ) + CaCl 2 ( l ) → CaTiO 3 ( s ) + FeCl x ( l, g ) FeTiO 3 ( s ) + CaCl 2 ( l ) + C ( s ) → TiO 2 ( s ) + FeCl x ( l, g ) + CO x ( g ) + Ca ( s ) Discussion CaTiO 3 can be utilized as a feed material of direct TiO 2 reduction processes (e.g., FFC, OS, EMR-MSE processes). Intensity, I(a. u.) Ilmenite FeTiO 3 Result of a selective chlorination experiment

14. 14 2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006 Low-grade Ti ore TiO 2 + flux (FeTiO x ) Fe removal by selective chlorination Ti powder Direct reduction of TiO 2 obtained after Fe removal Direct reduction of TiO 2 after Fe removal by electrochemical method

15. 15 2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006 Reduction experiment apparatus Fig. Schematic illustration of the experimental apparatus in this study. C + x O 2– → CO x + 2x e – Anode: Cathode: TiO 2 + 4 e – → Ti + 2 O 2– Electrolysis CaCl 2 molten salt Ti crucible Carbon anode TiO 2 feed Direct reduction by electrochemical method was applied.

16. 16 2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006 Reduction experiments Mass of element i, w i / g Ti oreCaCl 2 2.50R-1 R-2 R-30.79 2.50 Voltage, E /V Time, t” /h 1.5 3.0 3 3 3 CaTiO 3 R-42.503.03 1.50 ー 0.76 Exp. Experimental conditions ： Temperature: 1100 K Atmosphere: Ar Molten salt: CaCl 2 (800 g) Cathode: Ti crucible (I.D. 18 mm) Anode: Graphite rod (O.D. 3 mm) ー ー ー Table Analytical results of the sample obtained after electrochemical selective chlorination 0.295.91.90.1 2.00 Exp. D0.598.00.20.10.30.18 Exp. E0.296.90.30.20.50.28 UGI Concentration of element i, C i (mass%) VTiCaSi Fe Fe/Ti ratio, R Fe / Ti (%) Sample

17. 17 2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006 Result of the reduction experiments XRD analysis Fig. XRD pattern of the sample obtained after the reduction experiment (Exp. R-2) Angle, 2θ (degree) :Ti 2 O :CaTiO 3 Intensity, I(a. u.) CaTiO 3 was changed into Ti 2 O during this reduction experiment. Fig. XRD pattern (Cu-K  ) of the obtained powder sample after reduction at 1173 K using the EMR process. Intensity, I (a.u.) 9070503010 : Ti JCPDS # 44-1294 Angle, 2  (degree) Ti reduction by EMR In a previous study, low oxygen titanium powder was obtained. 2500 ppm O 40608010020 A complete reduction was not achieved in this study. Ref. T. Abiko, I. Park, and T.H. Okabe, Proceedings of 10th World Conference on Titanium, Ti-2003, (Hamburg, Germany, 13–18 July 2003), 253–260.

18. 18 2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006 Summary Ti powder Reduction by electrochemical method Low-grade Ti ore TiO 2 + flux (FeTiO x ) Iron removal by selective chlorination Development of an industrial scale process for producing low-cost titanium ・ The selective chlorination of Ti ore by using an electrochemical method was investigated, and 94% of Fe was successfully removed directly from low-grade Ti ore. ・ The feasibility of Ti smelting process for directly producing metallic Ti from low-grade Ti ore was demonstrated.

19. 19 2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006 Question and Answer

20. 20 2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006 History of Titanium 1791 First discovered by William Gregor, a clergyman and amateur geologist in Cornwall, England. 1795 Klaproth, a German chemist, gave the name titanium to an element re-discovered in Rutile ore. 1887 Nilson and Pettersson produced metallic titanium containing large amounts of impurities. 1910 M. A. Hunter produced titanium with 99.9% purity by the sodiothermic reduction of TiCl 4 in a steel vessel. (119 years after the discovery of the element) 1946 W. Kroll developed a commercial process for the production of titanium: Magnesiothermic reduction of TiCl 4... Titanium was not purified until 1910, and was not produced commercially until the early 1950s.

21. 21 2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006 (a) Production of titanium sponge in the world (2003). (b) Transition of production volume of titanium mill products in Japan. Year Amount of titanium mill products [kt] 17.4 kt (2004) Fig. Current status of titanium production, Total 65.5 kt USA 8 kt Japan 18.5 kt (28% share) Russia 26 kt Kazakhstan 9 kt China 4 kt (a) production of titanium sponge in the world (2003), (b) transition of production volume of titanium mill products in Japan. Titanium Production

22. 22 2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006 Melting point (K) Density (g / cc @298 K) Specific strength ((kgf / mm 2 ) / (g / cc)) Price (Yen / kg) Titanium Ti 1943 4.5 8 ~ 10 3000 ~ 0.1 Aluminum Al 933.3 2.7 3 ~ 6 600 20 Iron Fe 1809 7.9 4 ~ 7 50 800 Symbol Production volume (10 6 ton / year ・ world) Table Comparison between common metals and titanium. Clarke number a 0.46 (rank 10)7.56 (rank 3)4.7 (rank 4) a: Values in parentheses are the existence rank in the earth’s crust.

23. 23 2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006 Fig. Flowchart of the titanium production based on the Kroll process. Ti feed (TiO 2 ) Chlorine (Cl 2 ) Sponge Ti Ti ingot MgCl 2 + Mg CO 2, FeCl x,AlCl 3 etc. Other compounds MgCl 2 Chlorination Distillation Reduction Vacuum distillation Crushing / Melting Electrolysis Crude TiCl 4 Pure TiCl 4 Sponge Ti + MgCl 2 + Mg H 2 S etc. Reductant, Mg Reductant (C) Flowchart of the titanium production

24. 24 2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006 (a) Low grade titanium ore (ilmenite) (b) Up-graded titanium ore (UGI) Fig. (a) Composition of low grade titanium ore (ilmenite), and (b) that of up-graded titanium ore (up-graded ilmenite, UGI). FeO x 2% Others 3% TiO x 95% TiO x 45% FeO x 45% Others 10% Composition of titanium ore

25. 25 2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006 Importance 1. A large amount of chloride wastes (e.g., FeCl x ) are produced in the Kroll process. 2. Chloride waste treatment is costly, and it causes chlorine loss in the Kroll process. Ti ore (Ilmenite, FeTiO x )Upgraded Ilmenite (UGI) TiO x FeO x Others TiO x FeO x Others Upgrade Chloride wastes Discarded 1. Reduction of disposal cost of chloride wastes 2. Minimizing chlorine loss in the Kroll process 3. Improvement of environmental burden 4. Reduction of material cost using low grade ore Upgrading Ti ore for minimizing chloride wastes

26. 26 2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006 This study Advantages: 1.Utilizing chloride wastes from the Kroll process 2. Low cost Ti chlorination 3.Minimizing chlorine loss in the Kroll process caused by generation of chloride wastes Development of a new environmentally sound chloride metallurgy Effective utilization of chloride wastes Ti metal or TiO 2 production TiCl 4 feedFeCl x (+AlCl 3 ) Carbo-chlorination CO x Low-grade Ti ore Upgraded Ti oreFeCl x (+AlCl 3 ) (FeTiO X ) (TiO 2 ) MCl X Chlorine recoverySelective chlorination (Cl 2 ) Fe FeCl x TiCl 4 Ti scrap Refining process using FeCl x

27. 27 2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006 Reduction (in kiln) Fe 2+ / TiFe = 80~95% 145C° (2.5 kg/cm 2 )*4 hr *2 step (90% purity) IlmeniteReductant (Heavy oil etc.) Reduced oreHCl vapor Leached ilmeniteWaterSpray acidFuel (Synthetic rutile) 95%TiO 2 1%TiFe TiO 2 HCl aq. Leaching (in digestor)Filtration Roasting HCl Sol. TiO 2 Iron oxide Calcination Absorber HCl aq. (18~20% HCl) Fig. Flowsheet of the Benilite process. The Benilite process

28. 28 2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006 Gas + particleParticle Ilmenite Gas Reduced ilmenite TiO 2 (Synthetic rutile) TiO 2 92~93% TiFe 2.0~3.5% TiO 2 Reduction (in kiln) Leaching WasteMag. separator Acid Leaching Filtering / Drying Screen -1 mm +1 mm Cyclone Reduced ore Coal (low ash) Air NH 4 Cl H 2 SO 4 aq. Air Iron oxide + Sol. Iron oxideSol. Thickener Fig. Flowchart of the Beacher process. (Non. mag.) The Beacher process (WLS)

29. 29 2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006 Thermocouple Ceramic tube Fused CaCl 2 bath TiO 2 powder Cathode (stainless steel) Alumina tube Anode lead wire (W) Alumina crucible Graphite crucible (anode) Electric furnace TiO 2 (CaCl 2 ) + 4 e - → Ti + 2 O 2- (CaCl 2 ) Fig. Electrochemical reduction of TiO 2 in CaCl 2. (Ref. Mem. Fac. Eng., Nagoya Univ., 19, (1967) 164-166.) or TiO 2 (CaCl 2 ) + 2 Ca → Ti + 2 CaO

30. 30 2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006 Fig. The principle of electrochemical deoxidization of titanium. (Ref. Met. Trans. B, 24B, June, (1993) 449-455.) Cl 2 CO X CaCl 2 molten salt O 2- [O]in Ti Ti C e-e- Ca [O] O 2- Carbon anodeTi cathode e-e- O 2- Ca 2+ Cl - Ca 2+ Cl - Ca 2+ O 2- Ca 2+ Ca O (in Ti) + 2 e - → O 2- (in CaCl 2 )

31. 31 2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006 TiO 2 + 4 e - → Ti + 2 O 2 (in CaCl 2 ) Fig. Schematic illustration of the procedure of the FFC process. (Ref. Nature, 407, 21, Sep. (2000) 361.)

32. 32 2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006 FFC Process (Fray et al., 2000) C + x O 2- → CO x + 2x e - Anode: Cathode: TiO 2 + 4 e - → Ti + 2 O 2- Electrolysis (a1) (a2) OS Process (Ono & Suzuki, 2002) C + x O 2- → CO x + 2x e - Anode: TiO 2 + 2 Ca → Ti + 2 O 2- + Ca 2+ Cathode: Ca 2+ + 2 e - → Ca Electrolysis (b1) (b2) (b3) e-e- CaCl 2 molten salt TiO 2 preform Carbon anode e-e- TiO 2 powder CaCl 2 molten salt Carbon anode Ca Production process under investigation

33. 33 2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006 EMR / MSE Process (Electronically Mediated Reaction / Molten Salt Electrolysis) Production process under investigation TiO 2 + C → Ti + CO 2 Over all reaction (d) Ca → Ca 2+ + 2 e - Anode: Cathode: TiO 2 + 4 e - → Ti + 2 O 2- C + x O 2- → CO x + 2x e - Ca 2+ + 2 e - → Ca Cathode: Anode: Electrolysis (c4) (c1) (c2) (c3)

34. 34 2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006 (a) FFC Process (Fray et al., 2000) C + x O 2- → CO x + 2x e - Anode: Cathode: TiO 2 + 4 e - → Ti + 2 O 2- Electrolysis (a1) (a2) (b) OS Process (Ono & Suzuki, 2002) C + x O 2- → CO x + 2x e - Anode: TiO 2 + 2 Ca → Ti + 2 O 2- + Ca 2+ Cathode: Ca 2+ + 2 e - → Ca Electrolysis (b1) (b2) (b3) e-e- CaCl 2 molten salt TiO 2 preform Carbon anode e-e- TiO 2 powder CaCl 2 molten salt Carbon anode Ca e-e- Carbon anode CaCl 2 molten salt TiO 2 feed e-e- Current monitor / controller Ca-X alloy e-e- EMRMSE Fig. Schematic illustration of experimental apparatus for titanium smelting in the future. (C) EMR / MSE Process (Okabe et al., 2002) TiO 2 + C → Ti + CO 2 Over all reaction (d) Ca → Ca 2+ + 2 e - Anode: Cathode:TiO 2 + 4 e - → Ti + 2 O 2- C + x O 2- → CO x + 2x e - Ca 2+ + 2 e - → Ca Cathode: Anode: Electrolysis (c4) (c1) (c2) (c3)

35. 35 2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006 AdvantagesDisadvantages Kroll Process ◎ High purity titanium available × Complicated process ◎ Easy metal / salt separationSlow production speed ○ Established chlorine circulationBatch type process ○ Utilizes efficient Mg electrolysis ○ Reduction and electrolysis operation can be carried out independently FFC Process ◎ Simple processDifficult metal / salt separation ○ Semi-continuous processReduction and electrolysis have to be carried out simultaneously △ Sensitive to carbon and iron contamination △ Low current efficiency OS Process ◎ Simple processDifficult metal / salt separation ○ Semi-continuous process △ Sensitive to carbon and iron contamination △ Low current efficiencyPRP (Preform ◎ Effective control of purity Difficult recovery of reductant ◎ Flexible scalability Environmental burden by leaching ◎ Resistant to contamination ○ Small amount of fluxes necessary EMR / MSE Process ◎ Resistant to iron and carbon Difficult metal / salt separation when oxide ○ Semi-continuous process Complicated cell structure ○ Reduction and electrolysis operation △ Complicated processcan be carried out independently × × × × × × × × × Reduction Process) Features of several titanium production process and morphology contamination system

36. 36 2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006 Fig. Conceptual image of the new titanium reduction process currently under investigation (EMR / MSE process, Oxide system). e-e- Carbon anode CaCl 2 -CaO molten salt e-e- Current monitor / controller Ca-X reductant alloy e-e- A A V e-e- Feed preform (TiO 2 + CaCl 2 ) Product Ti pellets Ti (+ CaO + CaCl 2 ) VnVn CO x gas CaCl 2 -CaO TiO 2 + 4 e - = Ti + 2 O 2- Ca (Ca-X alloy) = Ca 2+ + 2 e - C + x O 2- = CO x + 2x e - Ca 2+ + 2 e - = Ca (Ca-X alloy) O 2-, Ca 2+ Ca (Ca-X alloy) Ca Nighttime electrolysis Daytime reduction

37. 37 2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006 Stainless steel cover Stainless steel plate R reductant Stainless steel reaction vessel Ti sponge getter Feed preform (MO ｘ + flux) TIG weld Fig. Schematic illustration of the experimental apparatus for producing titanium powder by means of the preform reduction process (PRP). MO x + R → M + RO 1.Amount of flux (molten salt) is small. 2.Easy to prevent contamination from reaction vessel and reductant. 3. Highly scalable. M = Nb, Ta, Ti R = Mg, Ca… Preform Reduction Process (PRP)

38. 38 2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006 Reductant vapor Feed powder Reductant (R = Ca, Mg) (a) Conventional Metallothermic Reduction(b) Preform Reduction Process (PRP) Reductant vapor Feed preform Reductant (R = Ca, Mg) Fig. Metal powder production process: (a) conventional metallothermic reduction, (b) preform reduction process (PRP).

39. 39 2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006 FeO x ( s ) + MgCl 2 ( l ) = FeCl x ( l ) + MgO ( s ) T = 1100 K, t’ = 1 h, Atmosphere : N 2, Ti ore (UGI) : 4 g, MgCl 2 : 2 g Experimental condition Fig. Experimental apparatus for selective-chlorination of titanium ore using MgCl 2 as a chlorine source. Carbon crucible Stainless steel susceptor Glass beads Stainless steel net RF coil Ceramic tube Glass flange Vacuum pump Quartz flange Deposit Mixture of Ti ore and MgCl 2 Chlorides Condenser Chlorination Reactor (FeCl x ．．． ) (Fe-free Ti ore) N 2 or N 2 +H 2 O gas Selective chlorination using MgCl 2

40. 40 2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006 FeO x ( s ) + MgCl 2 ( l ) = FeCl x ( l, g ) + MgO ( s ) Intensity, I (a. u.) 1030405060708020 Fig. XRD pattern of the deposit at chlorides condenser. The sample powder was sealed in Kapton film before analysis. XRD analysis Deposit obtained after selective -chlorination. → FeCl 2 was generated. 90100 : FeCl 2 XRF analysis Residue after selective-chlorination. → Fe was selective chlorinated. Angle, 2θ (deg.) Table Analytical results of titanium ore, the residue after selective chlorination, and the sample after reduction. These values are determined by XRF analysis. Concentration of element i, C i (mass %) Ti ore (UGI from Ind.) After heating sample V 0.75 1.50 Ti 95.10 96.45 Fe 2.29 0.43 Si 0.41 0.44 Al 0.12 0.37 98.300.050.380.120.52 After reduction sample Results of previous study

41. 41 2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006 Fig. Experimental apparatus for chlorination of titanium using FeCl 2 as a chlorine source. Heater Quartz tube Sample deposits (on Si rubber, NaOH gas trap and quartz tube) Carbon crucible Sample mixture: (e.g., FeCl 2 +Ti powder) Ti ( s ) + 2 FeCl 2 ( s ) = TiCl 4 ( g ) + 2 Fe ( s ) XRF analysis Table Analytical results of the samples before and after heating and the sample deposited on quartz tube and Si rubber. These values are determined by XRF analysis. Concentration of element i, C i (mass %) Residue before heating Residue after heating Ti 18.4 9.8 Fe 45.3 80.1 Cl 36.2 9.0 Dep. on quartz tube after heating Dep. on Si rubber after heating 3.550.446.1 64.9 0.934.1 Chlorination of Ti using FeCl 2

42. 42 2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006 Fig. Flowchart of new titanium smelting process from titanium ore discussed in this study. (CaCl 2 ) Ti metal Ti smelting by electrochemical method This study Low-grade Ti ore Upgraded Ti oreFeCl x (+ AlCl 3 ) (FeTiO x ) (TiO 2 ) MCl x Selective chlorination by electrochemical method Chlorine recovery Fe FeCl x TiCl 4 Ti scrap

43. 43 2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006 Iron removal process by electrochemical method Direct reduction process from Ti ore to Ti metal can be achieved. Establishment of a new up-grading process of Ti ore by electrochemical method.

44. 44 2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006 Fig. Schematic illustrations of the processes investigated in this study. (a) Iron removal process 2 Cl - → Cl 2 + 2 e - FeO x + Cl 2 + C → FeCl x + CO x Anode: Cathode:Ca 2+ + 2 e - → Ca Electrolysis (a1) (a2) (a3) e-e- Carbon crucible containing Ti ore + CaCl 2 mixture (Anode) SampleMolten CaCl 2 Mild steel crucible (Cathode) (b) FFC process (Fray et al., 2000) C + x O 2- → CO x + 2x e - Anode: Cathode:TiO 2 + 4 e - → Ti + 2 O 2- Electrolysis (b1) (b2) e-e- CaCl 2 molten salt TiO 2 preform Carbon anode

45. 45 2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006 @1100 K 2CaCl 2 + O 2 → 2CaO ＋ 2Cl 2 2MgCl 2 + O 2 → 2MgO ＋ 2Cl 2 4HCl + O 2 → 2H 2 O ＋ 2Cl 2 2CO + O 2 → 2CO 2 FeO + MgCl 2 → FeCl 2 + MgO 2C + O 2 → 2CO log p Cl 2 2 / p O 2 = -8.29 log p O 2 = -17.74 log p O 2 = -19.85 e.g. ΔG = -0.28 kJ < 0 log p Cl 2 2 / p O 2 = 1.49 log p Cl 2 2 / p O 2 = 0.48 Potential of several reaction

46. 46 2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006 Table Gibbs energy change of formation in the Fe-Ti-O system.

47. 47 2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006 0.51.01.52.02.5 0 -2 -4 -6 -8 -10 -12 Reciprocal temperature, 1000 T -1 / K -1 Vapor pressure, log p i (atm) Temperature, T / K Ti ( s,l ) Fe ( s,l ) TiCl 2 ( s ) TiCl 3 ( s ) TiCl 4 ( l ) FeCl 2 ( s,l ) FeCl 3 ( s,l ) 10005004002000 MgCl 2 ( s, l ) CaCl 2 ( s, l ) Region suitable for vaporization of chlorides Fig. Vapor pressure of iron, calcium, magnesium and titanium chlorides as a function of reciprocal temperature.

48. 48 2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006 e.g. -40 -10 -30 -20 -50 -60 0 -40-10-30-200 Fe-Cl-O system, T = 1100 K CaO ( s ) / CaCl 2 ( l ) a CaO = 0.1 C / CO eq. CO / CO 2 eq. Oxygen partial pressure, log p O 2 (atm) Chlorine partial pressure, log p Cl 2 (atm) FeO ( s ) Fe 2 O 3 ( s ) FeCl 2 ( l ) Fe 3 O 4 ( s ) FeCl 3 ( g ) Fig. Chemical potential diagram for Fe-Cl-O system at 1100 K. FeO x can be chlorinated by controlling oxygen and chlorine partial pressure. Ti ore : mixture of TiO x and FeO x. H 2 O ( g ) / HCl ( g ) MgO ( g ) / MgCl 2 ( l ) eq. Fe ( s ) FeO X ( s ) + MgCl 2 ( l ) → FeCl X ( l, g )↑ + MgO ( s, l ) Thermodynamic analysis (FeO x chlorination)

49. 49 2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006 Fig. Chemical potential diagram for Ti-Cl-O system at 1100 K. -40 -10 -30 -20 -50 -60 0 -40-10-30-200 TiO ( s ) TiO 2 ( s ) TiCl 4 ( g ) Ti 2 O 3 ( s ) TiCl 3 ( s ) Ti 3 O 5 ( s ) Oxygen partial pressure, log p O 2 (atm) Ti-Cl-O system, T = 1100 K Chlorine partial pressure, log p Cl 2 (atm) CaO ( s ) / CaCl 2 ( l ) a CaO = 0.1 C / CO eq. CO / CO 2 eq. Fe / FeCl 2 eq. Since TiCl 4 is highly volatile species, chlorine partial pressure must be kept in the oxide stable region. TiCl 2 ( s ) H 2 O ( g ) / HCl ( g ) MgO ( g ) / MgCl 2 ( l ) eq. Ti 4 O 7 ( s ) Ti ( s ) Thermodynamic analysis (TiO x chlorination) Ti ore : mixture of TiO x and FeO x.

50. 50 2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006

51. 51 2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006 (CaCl 2 ) Ti metal Ti smelting by electrochemical method This chapter Low-grade Ti ore Upgraded Ti oreFeCl x (+ AlCl 3 ) (FeTiO x ) (TiO 2 ) MCl x Selective chlorination by electrochemical method Chlorine recovery Fe FeCl x TiCl 4 Ti scrap Fig. Flowchart of the new titanium smelting process discussed in this study.

52. 52 2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006 Sintered feed preform Feed preform Mixing Slurry Preform fabrication Ti ore Flux Binder Calcination / Iron removal Flux : CaCl 2, MgCl 2 Binder: Collodion FeCl x Fig. Flowchart of the procedure of preform fablication supplied for Fe removal experiment.

53. 53 2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006 Table Composition of titanium ore (ilmenite) and up-graded ilmenite (UGI) used this study.

54. 54 2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006 Table Starting materials used in this study. Form Liquid Supplier 5.0 Chip98.0up Powder95.0up Collodion a Ti CH 3 COOH CaCl 2 Ca Purity or conc. (%) Wako Pure Chemical., Inc. Osaka Tokusyu Goukin Co., Ltd. Kanto Chemicals, Inc. Sponge98.0upToho Titanium Co., Ltd. Liquid99.7Kanto Chemicals, Inc. Materials a : 5 mass% nitro cellulose, 23.75 mass% ethanol, 71.25 mass% diethylether. HCl 2-Propanol Liquid35Kanto Chemicals, Inc. Liquid99.5upKanto Chemicals, Inc. Aceton Graphite 99.0up 99.98 Liquid Crucible Kanto Chemicals, Inc.

55. 55 2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006 Experimental apparatus Electrochemical interface Electrochemical control unit 10 A power source Sample Molten CaCl 2 Mild steel crucible (Cathode) Graphite crucible containing Ti ore (Anode) Voltage monitor / controller e-e- Holes on crucible Furnace

56. 56 2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006 Ceramic insulator Thermocouple Heater Rubber plug Ar inlet Wheel flange Reaction chamber Preform containing Ti ore Stainless steel tube Molten salt (CaCl 2 ) Potential lead (Nickel wire) Graphite crucible Mild steel crucible V1V1 V2V2 A1A1 A2A2 Fig. Schematic illustration of the experimental apparatus in a voltage measurement. Ti ore, sample

57. 57 2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006 Surface of molten salt Support rod (Stainless steel tube) Sample (Ti ore, CaCl 2 etc.) Inlet of molten salt Screw (Stainless steel) Graphite crucible Air hole Fig. Schematic illustration of the graphite crucible used in this experiment, (a) appearance, (b) inner content. I.D. 17 mm O.D. 19 mm 40 mm (a)(b)

58. 58 2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006 Fig. Variation of the external current from the dipped preform to the graphite crucible.

59. 59 2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006 Fig. Electromotive force between the dipped preform and the graphite crucible.

60. 60 2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006 Table Analytical results of various samples a. Concentration of element i, C i (mass%) b Fe 42.4 33.7 Ti 50.4 50.6 Ca 0.2 7.1 41.441.99.6 R Fe / Ti (%) 84.1 66.6 98.8 AlSiClCr 0.90.0 3.7 5.3 2.4 2.7 0.04.32.5 0.6 0.3 40.736.110.888.78.72.01.30.3 50.142.20.184.30.04.03.30.3 Fe / Ti ratio c, Sample # a : Ilmenite (FeTiOx) produced in China. b : Determined by X-ray fluorescence analysis. This value excludes carbon and gaseous elements. c : Indicator of iron removal from titanium ore. A B D C E

61. 61 2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006 Fig. Phase diagram for the CaCl 2 -FeCl 2 system [2]. Liquid 674 ℃ 592 ℃ 782 ℃ 800 700 600 Temperature, T / ℃ 0100 CaCl 2 FeCl 2 FeCl 2 content, x FeCl 2 (mol%) 20406080

62. 62 2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006 Ceramic insulator Thermocouple Heater Rubber plug Ar inlet Wheel flange Reaction chamber Stainless steel tube Molten salt (CaCl 2 ) Potential lead (Nickel wire) Nickel quasi-reference electrode Mild steel crucible (working) Graphite crucible (counter) Ti ore A Fig. Schematic illustration of the experimental apparatus for cyclic voltammetry in molten CaCl 2. V1V1 V2V2

63. 63 2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006 -2 Potential (vs Ni quasi-ref.), E / V 01 Current, i / A 2 1 0 2 1 0 2 3.2 V 2 Cl - = Cl 2 + 2 e - (on C) Ca 2+ + 2 e - = Ca (on Fe) (a) (b) Fig. Cyclic voltammograms for molten CaCl 2 at 1100 K (a) before pre-electrolysis, (b) after pre-electrolysis, cathode sweep; working: Fe rod; counter: C rod, anode sweep; working: C rod; counter: Fe rod, scan rate: 100 mV / s, immersion length: 4 cm.

64. 64 2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006 Table Standard Gibbs energy of formation and theoretical voltage for reactions in this study.

65. 65 2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006 012-23 Current, i / A 2 1 0 2 1 0 2 1 0 3.0 V 2 Cl - = Cl 2 + 2 e - (on C) Ca 2+ + 2 e - = Ca (on Fe) 1.7 V C + x O 2- = CO x + 2x e - (on C) Ca 2+ + 2 e - = Ca (on Fe) 1.7 V C + x O 2- = CO x + 2x e - (on C) Ca 2+ + 2 e - = Ca (on Fe) (a) (b) (c) Potential (vs Ca / Ca 2+ ref.), E / V Fig. Cyclic voltammograms for molten CaCl 2 at 1100 K after Ca deposition using various carbon electrode, (a) C rod, scan rate: 100 mV / s, (b) C crucible, scan rate: 100 mV / s, (c) Ti ore holding C crucible, scan rate: 20 mV / s, cathode sweep; working: Fe rod; counter: Carbon, anode sweep; working: Carbon; counter: Fe rod, immersion length: 2 cm.

66. 66 2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006 Fig. Phase diagram for the CaCl 2 –Ca system [3]. Temperature, T ’ / ˚C 120 0 1100 900 800 1000 700 CaCl 2 Ca content, x Ca (mol%) Ca 204060080100 Liq. Two liquids 825˚828˚ 767˚

67. 67 2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006 Sample Molten CaCl 2 Mild steel crucible (Cathode) Carbon crucible containing Ti ore + CaCl 2 mixture (Anode) e-e- Fig. Schematic illustration of experimental apparatus for iron removal by electrochemical method.

68. 68 2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006 Fig. Schematic illustration of the experimental apparatus for iron removal by electrochemical method. V A Ceramic insulator Thermocouple Heating element Rubber plug Ar inlet Wheel flange Stainless steel reaction chamber Stainless steel tube Molten salt (CaCl 2 ) Potential lead (Nickel wire) Mild steel crucible (Cathode) Graphite crucible (Anode) Ti ore

69. 69 2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006 S L Ti ore ( + Fe 2 O 3 etc) Electrochemical iron removal Leaching TiO 2 powder CaCl 2 Waste solution CaCl 2 TiO 2 + CaCl 2 TiO 2 Vacuum drying Separation CH 3 COOH aq., HCl aq., Distilled water, Isopropanol, Acetone Fig. Flowchart of the procedure for iron removal experiment by electrochemical method. Distilled water

70. 70 2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006 Experiment 1 Experimental condition ： Temperature: 1100 K Atmosphere: Ar Molten salt: CaCl 2 (800 g) Cathode: Mild steel crucible (I.D 96 mm) Anode: Graphite crucible (I.D 17 mm) Sample Molten CaCl 2 Mild steel crucible (Cathode) Graphite crucible containing Ti ore (Anode) Voltage monitor / controller Mass of Ti ore (Ilmenite), w / g A4.00 B C Voltage, E / V Time, t’ / h 2.5 2.0 1.5 6 3 12 Exp. No. e-e-

71. 71 2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006 Result 1 XRF analysis After the electrochemical treatment, Fe in the Ti ore was selectively chlorinated and removed. Table Analytical results of the sample obtained after the electrochemical selective chlorination. Concentration of element i, C i (mass %) VTiFeCaSi Ti ore0.642.648.72.2 Exp. A0.964.229.60.51.8 Fe / Ti ratio, 114 49.5 Disscussion Ti ore (Ilmenite, FeTiO x ) Molten CaCl 2 Graphite crucible (Anode) Unreacted part Unreacted part was remained at the bottom of the graphite crucible. Exp. B1.255.425.313.81.145.6 Exp. C2.745.721.712.31.447.4 a: Average of the samples obtained from the upper part and lower part of the graphite crucible. R Fe / Ti (%) e-e- Sample

72. 72 2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006 Mass of feed materials i, w i / g Table Experimental condition for iron removal from Ti ore by electrochemical method c. UGI a A a: Upgrade ilmenite by the Benilite process (see Fig.1-6 ). The ore was produced in India (see Table 3-1). b: Ilmenite (FeTiO x ) produced in China. c: Temperature: 1100 K, Ar atmosphere. Exp. B Ilmenite b C D E F G 2.76 2.82 2.91 2.88 2.81 2.75 2.92 2.0 1.2 0.5 2.0 1.0 0.5 1.0 3.0 6.0 0.5 1.0 Voltage, V / volts Reaction time, t / hr H I J K L M N 4.00 4.03 3.99 4.00 3.93 4.01 2.5 1.5 1.0 0.5 ー 1.5 3.0 6.0 9.0 6.0 O 4.002.013.0 1.421.21.0 P Mass of feed materials i, w i / g UGI a Exp. Ilmenite b Voltage, V / volts Reaction time, t / hr

73. 73 2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006 Fig. Schematic illustration of electrochemical interface in this experiment. 10 A Power Source 20 cm

74. 74 2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006 Fig. Current generated by imposed each voltage. Time, t / second Current, I / A Exp. K Exp. L Exp. M Exp. N

75. 75 2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006 Table Analytical results of the samples obtained after iron removal by electrochemical method.

76. 76 2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006 Ceramic insulator Thermocouple Heater Rubber plug Ar inlet Wheel flange Stainless steel tube (Electrode) Molten salt (CaCl 2 ) Potential lead (Ni wire) Mild steel crucible (Cathode) V1V1 V2V2 A1A1 A2A2 Graphite crucible (Anode) Ti ore + CaCl 2 mixture 100 mm Fig. Schematic illustration of experimental apparatus in this experiment.

77. 77 2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006 Fig. Current value passed by imposed certain voltage, and voltage in this experiment, Exp. F.

78. 78 2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006 Fig. XRD pattern of the obtained sample after selective chlorination experiment. Intensity, I (a. u.) : CaTiO 3 (JCPDS #42-0423) Angle, 2 θ (degree) : TiO 2 (JCPDS #21-1276)

79. 79 2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006 Table Experimental condition and analytical results of the chlorination experiment using ilmenite.

80. 80 2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006 Table Experimental conditions and analytical results of the chlorination experiment using UGI.

81. 81 2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006 (CaCl 2 ) Ti metal Ti smelting by electrochemical method This chapter Low-grade Ti ore Upgraded Ti oreFeCl x (+ AlCl 3 ) (FeTiO x ) (TiO 2 ) MCl x Selective chlorination by electrochemical method Chlorine recovery Fe FeCl x TiCl 4 Ti scrap Fig. Flowchart of new titanium smelting process from titanium ore discussed in this chapter.

82. 82 2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006 Ceramic insulator Thermocouple Heater Rubber plug Ar inlet Wheel flange Reaction chamber Stainless steel tube Molten salt (CaCl 2 ) Potential lead (Nickel wire) Mild steel crucible Ti crucible (Cathode) Mixture of Ti ore after Fe removal and CaCl 2 A Fig. Schematic illustration of the experimental apparatus for electrochemical reduction of Ti ore after Fe removal. V Graphite rod (Anode)

83. 83 2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006 S L Ti ore (+Fe 2 O 3 etc) CaCl 2 Mixing Electrochemical reduction Leaching Ti powder Waste solution Mixture CaCl 2 Ti + CaCl 2 Vacuum drying CH 3 COOH aq., HCl aq., Distilled water, Isopropanol, Acetone Fig. Flowchart of the experimental procedure for electrochemical reduction of Ti ore after Fe removal.

84. 84 2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006 Table Experimental conditions for electrochemical reduction of Ti ore after Fe removal. Mass of feed material i, C i / g Ti oreCaCl 2 2.50R1 R2 R30.79 a 2.50 Voltage, E / V Time, t” / h 1.5 3.0 3 3 3 CaTiO 3 R42.503.03 1.50 ー 0.76 b Exp. No. ー ー ー a: The sample obtained by selective chlorination exp. A. b: The sample obtained by selective chlorination exp. D.

85. 85 2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006 Fig. Phase diagram for the CaCl 2 –CaO system. 1150 K 1000 950 900 85 0 800 75 0 700 CaCl 2 1020 CaO content, x CaO (mol%) 30 CaO 0 Temperature, T ’ / ˚C