(CaCl 2 )

1. Chlorination Ti ore + C + 2 Cl2 → TiCl4 (+ FeClx) + CO2 Features of titanium Lightweight and high strength Corrosion resistant Biocompatibility Some titanium alloys: shape-memory effect superelasticity Ilmenite (Ti ore) $ 0.1 ～ 0.2 / kg Ti Sponge titanium $ 10 / kg Ti Bulk metal $ 18 ～ 20 / kg Ti Bars & rods $ 30 ～ 50 / kg Ti Thermodynamic analysis Experiment Experiment ×50 ～ 100 ×2 ～ 5 0 - 10 - 20 - 30 - 40 - 50 - 60 - 40 - 30 - 20 - 10 0 Results Results Experimental condition: Experimental condition: T = 1100 K; t’ = 9 h; Atmosphere: Ar; Voltage, E = 1.5 V T = 1100 K; t ’= 1 h; Atmosphere: N2; Ti ore (UGI): 4 g, MgCl2: 2 g Concentration of element i, Ci (mass %)a Ti Fe Si Al V 2.29 0.41 0.12 0.75 Ti ore (UGI from Ind.) 95.10 0.43 0.44 0.37 1.50 After exp. 96.45 98.30 0.05 0.38 0.12 0.52 After reductionb Conclusions Future works Selective Chlorination of Titanium Ore by Electrochemical Method 電気化学的手法によるチタン鉱石の選択塩化 Isao Obana* and Toru H. Okabe** *Graduate School of Engineering, The University of Tokyo **Institute of Industrial Science, The University of Tokyo Introduction The Kroll process Titanium production process New Ti reduction process (EMR / MSE process) Reduction: Titanium reduction Features of the EMR process: Applications Aircraft Spacecraft Chemical plant Implant Artificial bone etc. ◎Resistant toiron and carbon contamination ○Semi-continuous process ○Reduction and electrolysis operations can be carried out independently. Cathode: TiO2 + 4 e- → Ti + 2 O2- Mg & TiCl4 feed port Anode: Ca → Ca2+ + 2 e- Electrolysis: Reductant production Sponge titanium ×Difficult metal / salt separation with oxide system ×Complicated cell structure △Complicated process Cathode: Comparison between titanium and common metals Ca2+ + 2 e- → Ca Anode: Al Fe Ti C + x O2- → COx + 2x e- Melting point (℃) 1660 660 1,540 Reduction Overall reaction Price (\ / kg) 600 50 3,000 TiCl4 + 2 Mg → Ti + 2 MgCl2 TiO2 + C → Ti + CO2 Production vol. (t / year・world) < 50,000 20,000,000 800,000,000 Electrolysis MgCl2 → Mg + Cl2 < 1/400 < 1/16,000 Wastes from the Kroll process Features of the Kroll process: Issues related to chloride wastes: 1. Disposal cost and environmental burden 2. Additional chlorine gas has to be purchased. 3. Effective utilization has not been established. ◎ High-purity Ti can be obtained. ◎ Metal / salt separation is easy. ○ Chlorine circulation is established. ○ Efficient Mg electrolysis can be utilized. ○ Reduction and electrolysis can be carried out independently. × Process is complicated. × Batch-type reduction process is used. × Production speed is low. × Chloride wastes cannot be utilized. FeOx Others Others Upgrade Chloride wastes FeOx TiOx TiOx Upgrading Ti ore for minimizing chloride wastes Upgraded Ilmenite (UGI) Ti ore (Ilmenite) Discarded This study (electrochemical method) New process Ti smelting process using low-grade Ti ore Selective chlorination・Iron removal process This study Ti ore: mixture of FeOxand TiOx Cathode： Fen++n e-→Fe Ca2++2 e- →Ca Low-grade Ti ore MClx FeClx Ti scrap Fe-Cl-O and Ti-Cl-O systems, T = 1100 K Anode　 ： 2 Cl-→Cl2+2 e- (FeTiOX) (CaCl2) 0 0 FeOx + C + Cl2 →FeClｘ(l, g) + COx Selective chlorination Chlorine recovery Potential region for selective chlorination - - 10 10 of iron ) ) CO / CO eq . Upgraded Ti ore FeClx Fe TiCl4 2 - - 20 20 atm atm C / CO eq . ( ( (+AlCl3) (TiO2) - - 30 30 2 2 O O p p MgO ( g ) / MgCl ( l ) eq . 2 log log - - 40 40 Ti smelting Advantages: 1. Material cost can be reduced by using low-grade ore. 2. Chlorine circulation in the Kroll process can be improved. 3. This process can also be applied to the new Ti production processes by the direct reduction of TiO2. H O ( g ) / HCl ( g ) eq . 2 - - 50 50 CaO ( s ) / CaCl ( l ) eq . 2 Ti metal a = 0.1 CaO - - 60 60 -– - 40 40 - - 30 30 - - 20 20 - - 10 10 0 0 log log p p ( ( atm atm ) ) Cl Cl 2 2 Fig. Chemical potential diagram for Fe-Cl-O and Ti-Cl-O systems at 1100 K. Earlier studies (pyrometallurgical methods) Iron removal from Ti ore by selective chlorination using MgCl2 is thermodynamically feasible. FeOx (s) + MgCl2 (l) = FeClx (l) + MgO (s) XRF analysis Vacuum pump Residue after selective chlorination → Fe was selectively chlorinated. Glass flange Glass beads Stainless-steel net Potentiostatic electrolysis XRF analysis Chloride Condenser Deposit Table Analytical results of titanium ore, the sample obtained after selective chlorination, and the sample after reduction. After the electrochemical treatment, Fe was selectively chlorinated and removed. Voltage of 1.5 V was imposed. Stainless-steel susceptor Carbon crucible Table Analytical results of titanium ore (starting sample) and the sample obtained after electrochemical selective chlorination. Chlorination Reactor Residue Mixture of Ti ore and MgCl2 Concentration of element i, Ci (mass %)a RF coil Quartz flange Ti Fe Si Al V Fe / Ti (%) Fig. Experimental result of potentiostatic electrolysis (Voltage, E = 1.5 V; Time, t’ = 9 h ≒ 32 ks) Ceramic tube 48.72 2.19 2.23 0.64 114 Ti ore 42.62 a: Value determined by XRF analysis b: Dechlorinated Ti ore was reduced by calciothermic reduction. N2 gas 16.22 0.97 0.88 1.76 After exp. 78.38 20.7 Fig. Experimental apparatus for selective chlorination of titanium ore using MgCl2 as a chlorine source. Average current at approximately 3 A passed for 9 h. 82% of Fe was successfully removed. Iron was removed from Ti ore by chemical methods. Iron was removed from Ti ore by the electrochemical method. Ti ore (TiO2 + FeOｘ) Low-value ore Ultimate goals: Selective chlorination of Ti ore by the electrochemical method was investigated, and 80 mass% Fe was successfully removed from low-grade Ti ore. ・A more efficient process for producing Fe-free Ti ore by the electrochemical method will be investigated. ・Behavior of chlorine in selective chlorination will beinvestigated. Low-cost Ti production directly from low-grade Ti ore will be established. Selective chlorination FeClx Direct reduction of oxides Fe-free TiO2 ・・・・・・ Ti smelting Metal Ti metal