Recycling Titanium Metal Scraps by Utilizing Chloride Wastes

Transcription

1 Recycling Titanium Metal Scraps by Utilizing Chloride Wastes Haiyan Zheng 1, Ryosuke Matsuoka and Toru H. Okabe 2 1 Department of Materials Engineering, Graduate School of Engineering, The University of Tokyo 2 International Research Center for Sustainable Materials, Institute of Industrial Science, The University of Tokyo EMC 2005 September 18-21, Dresden, Germany 1

2 Titanium? Aerospace industry Feature of Titanium 1. Light and high-strength 2. Corrosion resistance 3. Biocompatibility 4. 10th most abundant element in the earth s crust Japan Aerospace Exploration Agency Ocean industry Implant Buildings The JAPAN TITANIUM SOCIETY TMinato-Machi River Place (Osaka Japan) EMC 2005 September 18-21, Dresden, Germany 2

3 Current status of titanium production (2003) (a) Production of titanium sponge in the world (b) Transition of production volume of titanium mill products in Japan 16 USA 8 kt Kazakhstan 9 kt China 4 kt Total 65.5 kt Japan 18.5 kt (28% share) Russia 26 kt Amount of titanium mill products [kt] kt (2003) Year EMC 2005 September 18-21, Dresden, Germany 3

4 Comparison with common metals Metal Iron Aluminum Titanium Symbol Fe Al Ti Melting point (K) Density (g/cm K) Specific strength ((kgf/mm 2 )/(g/cm 3 )) 4~7 3~6 8~10 Clarke No Price ( /kg) Production volume (t/world@2003) 9.6 x x x / /300 Production volume of metallic titanium substantially small EMC 2005 September 18-21, Dresden, Germany 4

5 Kroll Process Chlorination: Ti ore (s) + C (s) + 2 Cl 2 (g) TiCl 4 (l) + CO 2 (g) Reduction: TiCl 4 (l) + 2 Mg (s) Ti (s) + 2 MgCl 2 (l) Electrolysis: MgCl 2 (l) Mg (s) + Cl 2 (g) Reduction Reactor for the Kroll Process Mg & TiCl 4 feed port Mg & MgCl 2 recovery port Metallic reaction vessel MgCl 2 recovery port Sponge titanium Ti / Mg / MgCl 2 mixture Furnace The essential advantage: High-purity Ti The critical disadvantage: Low productivity Batch type process Slow production speed EMC 2005 September 18-21, Dresden, Germany 5

6 Chlorine cycle in the Kroll process Cl 2 C Ti ore Carbo-chlorination Additional Cl 2 supply to compensate for chlorine loss TiCl 4 MgCl 2 CO x Chloride wastes Chlorine loss Reduction Mg Ti Chlorine in the Kroll process is recycled, but the generation of chloride waste causes chlorine loss in the process. Electrolysis Cl 2 Mg EMC 2005 September 18-21, Dresden, Germany 6

7 Upgrading Ti ore for minimizing chloride wastes FeO x Others TiO x Upgrade FeO x TiO x Others Chloride wastes Ti ore (eg. Ilmenite) Upgraded Ilmenite (UGI) Discarded Problems: When low-grade ore is used, a large amount of chloride wastes (e.g., FeCl x ) are generated in the Kroll process. Disposal cost of chloride wastes Environmental issues Causes chlorine loss in the process Currently expensive upgraded ilmenite ore (UGI) is used for reducing chloride waste and environmental burden. EMC 2005 September 18-21, Dresden, Germany 7

8 Concept of this study Possibility of utilizing low-grade titanium ore in the Kroll process or in the new smelting process, such as the PRP Low-grade Ti ore (FeTiO X ) MCl x (Cl 2 ) Selective chlorination My study FeCl x Main topic Ti scrap Chlorine recovery Reduction in chlorine loss, disposal cost of chloride wastes, and raw material cost Upgraded Ti ore (TiO 2 ) Ti Ti smelting FeCl x (+ AlCl 3 ) (e.g., Kroll process or PRP process) MCl x (M = Fe, Al, Si ) Fe TiCl 4 Low-cost process for titanium scraps recovery Diminished environmental burden EMC 2005 September 18-21, Dresden, Germany 8

9 Selective chlorination ( Upgrading low-grade titanium ore using CaCl 2 ) FeO x (FeTiO x, s) + HCl (g) FeCl x (g) + H 2 O (g) FeO x (FeTiO x, s) + CaCl 2 (s, l) FeCl x (g) + CaO (CaTiO x, s) EMC 2005 September 18-21, Dresden, Germany 9

10 Selective chlorination experiment Vacuum pump Chloride Condenser Chlorination Reactor Deposit obtained after exp. Stainless steel susceptor Graphite crucible Sample RF coil Quartz tube Ceramic tube Experimental condition: Low-grade Ti ore : 3 g, CaCl 2 : 2 g, T = 1100 K, t = 6 h, Graphite crucible, Atmosphere : N 2 + H 2 O. gas Experimental apparatus for the selective chlorination of titanium ore using Radio Frequency (RF) furnace. 10 cm The concentration of iron in the titanium ore decreased from 54%to 16% (XRF). Iron removal from the titanium ore was carried out successfully. EMC 2005 September 18-21, Dresden, Germany 10

11 Chlorine recovery ( Recovery of chlorine from chloride wastes by utilizing titanium metal scraps) FeCl x (l, g) + Ti (s) Fe (or FeTi, s)+ TiCl 4 (g) EMC 2005 September 18-21, Dresden, Germany 11

12 Oxygen partial pressure, log p O2 (atm) Ti-Cl-O system, p Cl2 = 0.1 atm TiO 2 (s) C (s)/co 2 (g) eq. TiCl 4 (g) Temperature T / K Chemical potential diagram for the Ti-Cl-O system. CO (g)/co 2 (g) eq. C (s)/co (g) eq. TiCl 4 is generated by the chlorination of TiO 2 when C or CO is introduced into the system under a high p Cl2 atmosphere. When p O2 is high, TiCl 4 cannot be obtained even under a high p Cl2 atmosphere. EMC 2005 September 18-21, Dresden, Germany 12

13 Ti (s) + FeCl x (l, g) TiCl 4 (g) + Fe (or FeTi, s) Fe-Ti-Cl system, T = 1100 K log p Cl2 (atm) FeCl 3 (g) FeCl 2 (l) Fe (s) log a Ti A FeTi (s) Cl 2 (g) B TiCl 4 (g) TiCl 3 (s) TiCl 2 (s) Ti (s) log a Fe Chemical potential diagram for the Fe-Ti-Cl system at 1100 K. Chlorine present in the iron chlorides can be extracted by metallic titanium. TiCl 4 can be obtained. EMC 2005 September 18-21, Dresden, Germany 13

14 Vapor pressure, log p i (atm) Fe (s,l) TiCl 2 (s) Ti (s,l) Temperature, T / K TiCl 3 (s) FeCl 2 (s,l) TiCl 4 (l) FeCl 3 (s,l) Region suitable for vaporization chlorides The separation of chlorides and recovery of high-purity TiCl 4 are possible by controlling the deposition temperature Reciprocal temperature, 1000 T -1 /K -1 Vapor pressure of some chlorides as a function of reciprocal temperature. EMC 2005 September 18-21, Dresden, Germany 14

15 Chlorine recovery experiment Ti (s) + 2 FeCl 2 (s, l) TiCl 4 (g) + 2 Fe (s) Deposits after the experiment Quartz tube Graphite crucible Vacuum pump Ar gas Silicone rubber plug NaOH gas trap Heating element Sample mixture e.g., FeCl 2 + Ti powder Experimental condition: Ti: 0.3 g, FeCl 2 : 2 g T = 1100 K, t = 6 h, Graphite crucible, Atmosphere : Ar. 5 cm Experimental apparatus for chlorination of titanium using FeCl 2 as chlorine source. EMC 2005 September 18-21, Dresden, Germany 15

16 Results of chlorine recovery (1) Assembled Quartz tube after experiment. 5 cm The form of the obtained residue and deposit after experiment. Solid (White) Flake (Brown) Powder (Black) Deposit on the surface of the NaOH gas trap (A) Deposit inside the quartz tube (B) Residue in the graphite Crucible after heating (C) The product/mixture of TiCl 4 + NaOH EMC 2005 September 18-21, Dresden, Germany 16

17 Results of chlorine recovery (2) Table: Analytical results of the samples before and after heating, and the deposits btained within the quartz tube and on the surface of the NaOH gas trap after heating. Exp. # CB Concentration of element i, C i (mass%) a Ti Fe Cl Initial sample in the graphite crucible before heating Residue in the graphite crucible after heating (C) n.d. Deposit inside the quartz tube (B) Deposit on the surface of the NaOH gas trap (A) a: Determined by XRF analysis, n.d. = not detected (below 0.1% ) Chlorine in FeCl 2 was extracted as TiCl 4 by metallic Ti. Fe was generated at heating zone. Chlorine in FeCl x was extracted by metallic Ti. EMC 2005 September 18-21, Dresden, Germany 17

18 Results of chlorine recovery (3) XRD patterns of the sample before experiment (a) and the residue after experiment (b) (Exp. # CB) (a) Sample mixture before experiment Intensity, I (a. u.) : α -Ti (JCPDS # ) : FeCl 2 2H 2 O (JCPDS # ) Angle, 2 (deg.) (b) Residue obtained after experiment Intensity, I (a. u.) : α - Fe (JCPDS # ) Angle, 2 (deg.) Ti (s) + FeCl 2 (s, l) TiCl 4 (g) + Fe (s) Fe was generated at heating zone. Chlorine in FeCl x was extracted by metallic Ti. EMC 2005 September 18-21, Dresden, Germany 18

19 Low-grade Ti ore (FeTiO X ) Summary MCl x (Cl 2 ) My study FeCl x Main topic Ti scrap Selective chlorination Chlorine recovery Upgraded Ti ore (TiO 2 ) FeCl x (+ AlCl 3 ) Fe TiCl 4 Ti Ti smelting (e.g., Kroll process or PRP process) MCl x (M = Fe, Al, Si ) The feasibility of the new recycling process of chlorine in the chloride waste by metallic Ti is demonstrated from the thermodynamic viewpoint. According to the experiment, chlorine recovery from FeCl 2 using Ti was demonstrated and TiCl 4 can be obtained EMC 2005 September 18-21, Dresden, Germany 19

20 Future Work 1. The detailed mechanism and the mass balance of the chlorination reactions are under investigation. 2. Chloride wastes from the Kroll process will be investigated in the future. 3. The recycling process of other reactive metal scraps by chloride waste will be investigated. EMC 2005 September 18-21, Dresden, Germany 20

21 Recycling Titanium Metal Scraps by Utilizing Chloride Wastes Haiyan Zheng Toru H. Okabe International Research Center for Sustainable Materials, Institute of Industrial Science, The University of Tokyo EMC 2005 September 18-21, Dresden, Germany 21

22 For Questions EMC 2005 September 18-21, Dresden, Germany 22

23 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 rediscovered in Rutile ore 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. EMC 2005 September 18-21, Dresden, Germany 23

24 Titanium is the 10 th most abundant element in the earth s crust Rank Element Clark #. 1 8 O Si Al Fe Ca Na K Mg H Ti Cl Mn P C S 0.03 The tenth most abundant element Rank Element Clark # N F Rb Ba Zr Cr Sr V Ni Cu W Li Ce Co Sn Exhausting element EMC 2005 September 18-21, Dresden, Germany 24

25 Amount of titanium products, w i / kt Sponge Ti Mill product Year Amount of titanium products, w i / kt Ref (1) Ref (2) Sponge Ti Mill product Ref (1) Ref (1) Ref (2) Year Ref (2) Transition of production volume of titanium sponge and mill products in China. Ref(1): China Titanium Association (Courtesy of Mr. Akiyama, JTS) Ref(2): China Titanium Association (H. Z., Private communication) EMC 2005 September 18-21, Dresden, Germany 25

26 Ocean engineering 0.03 kt (0.28%) Glasses 0.08 kt (0.79%) Medical 0.09 kt (0.97%) Ship 0.19 kt (1.98%) Metallurgy 0.20 kt (2.06%) Other sports leisure 0.20 kt (2.14%) Salt industry 0.23 kt (2.43%) Electric power 0.42 kt (4.49%) Watch 0.47 kt (4.99%) Export 0.82 kt (8.70%) Aerospace 0.91 kt (9.61%) Others 0.92 kt (9.77%) Chemical industry 4.13 kt (43.67% ) Total 9.45 kt Golf 1.00 kt (10.60%) Shipments of titanium mill product in various field s application in China (2004). EMC 2005 September 18-21, Dresden, Germany 26

27 Ilmenite Coal (low ash) Air Reduction (in kiln) Reduced ore Gas + particle Particle -1 mm Screen +1 mm Cyclone Gas Mag. separator Reduced ilmenite Waste NH 4 Cl (Non. mag.) Air Leaching TiO 2 H 2 SO 4 aq. Iron oxide + Sol. Acid Leaching Thickener TiO 2 Iron oxide Sol. Filtering / Drying TiO 2 (Synthetic rutile) TiO 2 92~93%; TiFe 2.0~3.5% Flowchart of the Beacher process. EMC 2005 September 18-21, Dresden, Germany 27

28 Ilmenite Reductant (Heavy oil etc.) Fe 2+ / TFe = 80~95% Reduction (in kiln) (18~20% HCl) Reduced ore HCl aq. HCl vapor Leaching (in digestor) 145C (2.5 kg/cm 2 ) *4 hr *2 step Leached ilmenite Water Spray acid Fuel Filtration Roasting TiO 2 Sol. Iron oxide (90% purity) HCl Calcination Absorber TiO 2 (Synthetic rutile) 95% TiO 2 1% TiFe Flowchart of the Benilite process. HCl aq. EMC 2005 September 18-21, Dresden, Germany 28

29 Features of reductant and feed materials in metallothermic reduction process. Mg Na Ca TiCl 4 Possible to remove Mg and MgCl 2 by distillation. Possible to efficiently eletrosis MgCl 2 Easy to control purity (strong contamination of carbon) Difficult to remove Na Difficult to control the temperature Easy to purity control (strong resistance to Ni contamination) High enegy loss Difficult to remove Ca or CaCl 2 Cost of the reductant production TiO 2 Impossible to remove oxygen Impossible to remove oxygen Difficult to purity control Difficult to remove Ca or CaCl 2 Cost of the reductant production Process with strong resistace to Oxygen EMC 2005 September 18-21, Dresden, Germany 29

30 The Kroll process Ti feed (TiO 2 ) Reductant (C) Chlorine (Cl 2 ) Carbo-chlorination Crude TiCl 4 CO 2 FeCl x, AlCl 3 Distillation H 2 S etc. Pure TiCl 4 Other compounds Mg Reduction Electrolysis Sponge Ti + MgCl 2 + Mg Vacuum distillation Sponge Ti MgCl 2 + Mg Crushing / Melting MgCl 2 The essential advantage: High-purity titanium available. The critical disadvantage: Low productivity. Ti Ingot TiCl 4 (g) + 2 Mg (l) Ti (s) + 2 MgCl 2 (l) EMC 2005 September 18-21, Dresden, Germany 30

31 Gibbs energy change Table Gibbs energy change of formation and reaction in the Fe-Ti-O system. Reactions Gibbs energy change, G o f or Go r (kj/mol) 1100 K 1200 K 1300 K 1273 K a Fe (s) O2 (g) = FeO (s) Ref Ti (s) + O2 (g) = TiO2 (s) Fe (s) + Ti (s) O2 (g) = FeTiO3 (s) Fe (s) + Ti (s) + 2 O2 (g) = Fe2TiO4 (s) TiO 2 (s) + Fe (s) O2 (g) = FeTiO3 (s) TiO 2 (s) + 2 Fe (s) + O2 (g) = Fe2TiO 4 (s) TiO 2 (s) + FeO (s) = FeTiO 3 (s) , , , , TiO 2 (s) + 2 FeO (s) = Fe2TiO4 (s) a: interpolated , , , , 8 References [1] I. Barin, Thermochemical Data of Pure Substances, 3rd ed., (Weinheim, Federal Republic of Germany, VCH Verlagsgesellschaft mbh, 1997). [2] Outokumpu HSC Chemistry for Windows, Version 5.0, (Finland, Outokumpu Research Oy Information Service, 2002). [3] O. Knacke, O. Kubaschewski, and K. Hesselmann, Thermochemical Properties of Inorganic Substances, 2nd ed., (Berlin, Federal Republic of Germany, Springer-Verlag, 1991). [4] NIST-JANAF Thermochemical Tables 4th ed., U.S. Bureau of Standards (1998). [5] S. Ito, Phase Equilibria of the Titanium-Iron-Oxygen system as 1,273 K on Titanium Extraction Processing, (Journal of the Mining and Materials Processing Institute of Japan (Vol. 112, p , 1996). [6] J. S. J. Van Devender, Kinetics of Selective Chlorination of ilmenite, (Thermochimica Acta, vol. 124, p , 1988). [7] Special Lecture for the Process Design of the Recycling Material, Distributed Documents, (Summer term, 2003) [8] O. Kubaschewski, High Temp. High pressures 4.1 (1972). a: Interpolated TiO x + FeO = Ti x Fe y O z DG r = -30 ~ -9 kj / mol EMC 2005 September 18-21, Dresden, Germany 31

32 . Selective chlorination ( Upgrading low-grade titanium ore using CaCl 2 ) FeO x (FeTiO x, s) + HCl (g) FeCl x (g) + H 2 O (g) FeO x (FeTiO x, s) + CaCl 2 (s, l) FeCl x (g) + CaO (CaTiO x, s). Chlorine recovery ( Recovery of chlorine from chloride wastes by utilizing titanium scraps) FeCl x (l, g) + Ti (s) Fe (or FeTi, s)+ TiCl 4 (g) EMC 2005 September 18-21, Dresden, Germany 32

33 . Selective chlorination ( Upgrading low-grade titanium ore using CaCl 2 ) FeO x (FeTiO x, s) + HCl (g) FeCl x (g) + H 2 O (g) FeO x (FeTiO x, s) + CaCl 2 (s, l) FeCl x (g) + CaO (CaTiO x, s) EMC 2005 September 18-21, Dresden, Germany 33

34 FeO x chlorination (Ti ore: mixture of TiO x and FeO x. ) Fe-Cl-O system, T = 1100 K Oxygen partial pressure, log p O2 (atm) Fe 2 O 3 (s) Fe 3 O 4 (s) FeO (s) Fe(s) FeCl 3 (g) FeCl 2 (l) Chlorine partial pressure, log p Cl2 (atm) Chemical potential diagram for Fe-Cl-O system at 1100 K. CaO (s) / CaCl 2 (l) eq. H 2 O (g) / HCl (g) eq. CO (g) / CO 2 (g) eq. C (s) / CO (g) eq. H 2 O (g) + CaCl 2 (l) 2 HCl (g) + CaO (s) FeO x (FeTiOx, s) + HCl (g) FeCl 2 (l, g) + H 2 O (g) or FeO x (FeTiO x, s) + CaCl 2 (l) FeCl x (g) + CaO (CaTiO x, s) a CaO <<1 FeO x can be chlorinated using CaCl 2 + H 2 O. EMC 2005 September 18-21, Dresden, Germany 34

35 TiO x chlorination (Ti ore: mixture of TiO x and FeO x. ) Ti-Cl-O system, T = 1100 K Oxygen partial pressure, log p O2 (atm) TiO 2 (s) Ti 3 O 5 (s) Ti 2 O 3 (s) TiO (s) Ti (s) Ti 4 O 7 (s) TiCl 4 (g) TiCl 3 (s) TiCl 2 (s) Chlorine partial pressure, log p Cl2 (atm) Chemical potential diagram for Ti-Cl-O system at 1100 K. CaO (s) / CaCl 2 (l) eq. H 2 O (g) / HCl (g) eq. CO (g) / CO 2 (g) eq. C (s) / CO (g) eq. TiO x can not be chlorinated using CaCl 2, nor CaCl 2 +H 2 O. EMC 2005 September 18-21, Dresden, Germany 35

36 Ti ore chlorination (Ti ore: mixture of TiO x and FeO x. ) Fe-Cl-O system and Ti-Cl-O system, T = 1100 K Oxygen partial pressure, log p O2 (atm) Chlorine partial pressure, log p Cl2 (atm) Combine d chemical potential diagram for Fe-Cl-O (dotted line) system and Ti-Cl-O system (solid line) at 1100 K. H 2 O (g) / HCl (g) eq. CaO (s) / CaCl 2 (l) eq. Potential region for selective chlorination of iron CO (g) / CO 2 (g) eq. C (s) / CO (g) eq. FeO x (FeTiO x, s) + HCl (g) FeCl x (g) + H 2 O (g) FeO x (FeTiO x, s) + CaCl 2 (l) FeCl x (g) + CaO (CaTiO x, s) a CaO <<1 The selective-chlorination of Ti ore by CaCl 2 +H 2 O. EMC 2005 September 18-21, Dresden, Germany 36

37 Results of selective chlorination (chlorine source: CaCl 2 +H 2 O) H 2 O (g) + CaCl 2 (l) 2 HCl (g) + CaO (s) FeO x (s) + HCl (g) FeCl 2 (l, g) + H 2 O (g) Sample Ti ore b After exp. Ti Fe a: Value determined by XRF analysis. b: Ilmenite from Vietnam. or FeO x (FeTiO x, s) + CaCl 2 (l) FeCl x (g) + CaO (CaTiO x, s) Table: Analytical results of titanium ore and the residue obtained from the selective chlorination of titanium ore. (Exp. # SA) Concentration of element i, C i (mass%) a Al Si V Fe was selectively chlorinated. ( Iron removal from the titanium ore was carried out successfully. ) Furthermore, iron concentration levels below 8 % is currently under investigation. EMC 2005 September 18-21, Dresden, Germany 37

38 Fe-Cl-O system, T = 900 K 0 CaO (s) / CaCl 2 (s) eq. -10 Fe 2 O 3 (s) H 2 O (g) / HCl (g) eq. Oxygen partial pressure, log p O2 (atm) Fe 3 O 4 (s) FeO(s) Fe (s) FeCl 3 (g) FeCl 2 (s) MgO (s) / MgCl 2 (s) eq. C (s) / CO (g) eq. CO (g) / CO 2 (g) eq Chlorine partial pressure, log p Cl2 (atm) Chemical potential diagram for Fe-Cl-O system at 900 K. EMC 2005 September 18-21, Dresden, Germany 38

39 Fe-Cl-O system, T = 1300 K 0 Fe 2 O 3 (s) CaO (s) / CaCl 2 (l) eq. Oxygen partial pressure, log p O2 (atm) Fe 3 O 4 (s) FeO(s) Fe (s) FeCl 3 (g) FeCl 2 (g) H 2 O (g) / HCl (g) eq. MgO (s) / MgCl 2 (l) eq. CO (g) / CO 2 (g) eq. C (s) / CO (g) eq Chlorine partial pressure, log p Cl2 (atm) Chemical potential diagram for Fe-Cl-O system at 1300 K. EMC 2005 September 18-21, Dresden, Germany 39

40 Ti-Cl-O system, T = 900 K 0 Fe (s) / FeCl 2 (s) eq. FeCl 2 (s) / FeCl 3 (g) eq. CaO (s) / CaCl 2 (s) eq. -10 H 2 O (g) / HCl (g) eq. Oxygen partial pressure, log p O2 (atm) TiO 2 (s) Ti 4 O 7 (s) Ti 2 O 3 (s) TiO(s) TiCl 4 (g) TiCl 3 (s) MgO (s) / MgCl 2 (s) eq. C (s) / CO (g) eq. CO (g) / CO 2 (g) eq. Ti (s) TiCl 2 (s) Chlorine partial pressure, log p Cl2 (atm) Chemical potential diagram for Ti-Cl-O system at 900 K. EMC 2005 September 18-21, Dresden, Germany 40

41 Ti-Cl-O system, T = 1300 K 0 FeCl 2 (g) / FeCl 3 (g) eq. Fe (s) / FeCl 2 (g) eq. CaO (s) / CaCl 2 (l) eq. Oxygen partial pressure, log p O2 (atm) TiO 2 (s) Ti 3 O 5 (s) Ti 4 O 7 (s) Ti 2 O 3 (s) TiO(s) Ti (s) TiCl 4 (g) TiCl 3 (g) H 2 O (g) / HCl (g) eq. MgO (s) / MgCl 2 (l) eq. CO (g) / CO 2 (g) eq. C (s) / CO (g) eq Chlorine partial pressure, log p Cl2 (atm) Chemical potential diagram for Ti-Cl-O system at 1300 K. EMC 2005 September 18-21, Dresden, Germany 41

42 Fe-Cl-O system and Ti-Cl-O system, T = 900 K 0 CaO (s) / CaCl 2 (s) eq. Oxygen partial pressure, log p O2 (atm) B A Potential region for selective chlorination of iron C (s) / CO (g) eq. CO (g) / CO 2 (g) eq. H 2 O (g) / HCl (g) eq. MgO (s) / MgCl 2 (s) eq. Potential region for chlorination of TiO x Chlorine partial pressure, log p Cl2 (atm) Combined chemical potential diagram of the Fe-Cl-O system (dotted line) and Ti-Cl-O system (solid line) at 900 K. EMC 2005 September 18-21, Dresden, Germany 42

43 Fe-Cl-O system and Ti-Cl-O system, T = 1300 K 0 CaO (s) / CaCl 2 (l) eq. Oxygen partial pressure, log p O2 (atm) F E Potential region for selective chlorination of iron CO (g) / CO 2 (g) eq. C (s) / CO (g) eq. H 2 O (g) / HCl (g) eq. MgO (s) / MgCl 2 (l) eq. Potential region for chlorination of TiO x Chlorine partial pressure, log p Cl2 (atm) Combined chemical potential diagram of the Fe-Cl-O system (dotted line) and Ti-Cl-O system (solid line) at 1300 K. EMC 2005 September 18-21, Dresden, Germany 43

44 Ti-Cl-O system, T = 1100 K Oxygen partial pressure, log p O2 (atm) TiO 2 (s) Ti 3 O 5 (s) Ti 2 O 3 (s) TiO (s) Ti (s) FeCl 2 (l)/fecl 3 (g) eq. Fe (s)/fecl 2 (l) eq. Ti 4 O 7 (s) Chlorine partial pressure, log p Cl2 (atm) C CO (g)/co 2 (g) eq. C (s)/co (g) eq. Isothermal chemical potential diagram for the Ti-Cl-O system at 1100 K. D A B TiCl 4 (g) TiCl 3 (s) TiCl 2 (s) The chlorination of TiO 2 proceeds when FeCl 3 is reacted with TiO 2 in the presence of C (s) or CO (g). The chlorination of TiO 2 by FeCl 2 is difficult even at oxygen partial pressure under C (s)/co (g) equilibrium. EMC 2005 September 18-21, Dresden, Germany 44

45 Temperature Dependence of vapor pressure of some chlorides, e.g. Mg and Ca Vacuum distillation Reduction feasible Vacuum distillation 0 Mg -2 K Na MgCl 2 Ca Vapor pressure, log p i (atm) Mg TiCl 3 Ca MgCl 2 KCl CaCl 2-10 NaCl CaCl 2 Ti TiCl Temperature, T / K Vapor pressure of several chemical species. [Ref. I. Barin, Thermochemical Data of Pure Substances, VCH Verlagsgesellschaft, Weinheim, (1989).] EMC 2005 September 18-21, Dresden, Germany 45

46 Properties of TiCl x TiCl 4 TiCl 3 TiCl 2 Appearance Color Clear Red Black Molecular weight (g/mol) Density (g/cm 3 ) 1.70 No data 3.13 Melting point ( C) Boiling point ( C) Sublimation point ( C) G f at 800 C (kj/mol Cl 2 ) G f at 800 C (kj/mol Ti) Vapor pressure at 800 C (atm) EMC 2005 September 18-21, Dresden, Germany 46

47 Recent research works (PRP) (Metallothermic reduction process) Preform Reduction Process Feed preform Reductant vapor Reductant (R = Ca, Mg) TiO 2 (s) + Ca (g) Ti (s) + CaO (s) Features of PRP Merit: Suitable for uniform reduction Flexible scalability Possible to control the morphology of powder by varying the flux content in the preform Possible to prevent the contamination from reaction container and control purity Simple and low cost process Minimizing amount of waste solution Demerit: Leaching required Calcium production and control of calcium vapor EMC 2005 September 18-21, Dresden, Germany 47

48 Preform Reduction Process Feed preform Reductant vapor Reductant (R = Ca, Mg) Stainless steel cover Stainless steel net holder for preform feed Stainless steel holder for reductant (Ca, Mg ) TiO 2 + Ca Ti + 2 CaO EMC 2005 September 18-21, Dresden, Germany 48

49 Preform Reduction Process Ti ore Flux Binder Mixing Slurry Preform fabrication Room temperature, 6h Feed preform Ti ore: Rutile Flux: CaCl 2 Binder: Collodion Calcination/iron removal FeCl X 1273 K, Alumina Crucible, 1h Sintered feed preform Calcium vapor Reduction 1273 K, Airtight SUS Reactor,6h Reduced preform 50% CH 3 COOH aq., 20% HC aq., Distilled water, Isopropanol, Acetone Leaching Waste solution Vacuum drying Powder Flowchart of preform reduction process (PRP). EMC 2005 September 18-21, Dresden, Germany 49

50 (a) Intensity, I (a.u.) UGI : Ti JCPDS # Angle, 2 (deg.) (b) 5 m (a) XRD pattern of titanium powder obtained by preform reduction process. (b) Scanning electron microscopic (SEM) image.(exp. # A-2) EMC 2005 September 18-21, Dresden, Germany 50

51 Summary of Ti ore reduction by PRP Ti ore Experiment condition :Reduction temp. Reduction time Ti metal powder : T = 1273 K : t = 6 hr SEM image Flux : CaCl 2 Cationic molar ratio: X Cat. / T i = % Ti 5 m EDS analysis (mass %) Ti Ca Al Fe O (0.00) EMC 2005 September 18-21, Dresden, Germany 51

52 Welcome to Institute of Industrial Science, the University of Tokyo EMC 2005 September 18-21, Dresden, Germany 52