V 2 O 5 ( s ) + Al ( s ) ( + Fe ( s ))

1. (1) After calcination V Others 1.1 % MgO Japan 2.0 % Other 6.7 % Other 0.4 % Other 3.0 % Mg2V2O7 Catalyst 12.9 % Element China 15.2 % Crustal abundance (ppm) China 20.1 % China 31.1 % Russia 26.8 % Russia 38.3 % U.S.A 12.4 % China 38.3 % O, Si > 105 CaO JCPDS # 77-2010 Slag Total 6.42×103 t (pure V) Steel 86.0% 105 ～ 104 Other 40.1 % Al, Fe, Ca, Na, K, Mg Total 56.3×103 t (pure V) Total 13.0×106 t (pure V) Ca2V2O7 JCPDS # 72-2312 Total 46.0×103 t (pure V) Total 36.6×103 t (pure V) (2) After reduction V－Al (l) (Fe－V－Al (l)) 104 ～ 103 Ti, H, P Intensity, I (a.u.) South Africa 30.5 % Russia 14.9 % 103 ～ 102 V, Mn, S, C, Cl, 　・・・ 102 ～ 101 Cu, Ni, Zn, Nb, Co, Pb, 　・・・ Intensity, I (a.u.) South Africa 39.1 % South Africa 23.0 % South Africa 43.9 % ・・・ ・・・ Australia 14.2 % Hg, Ag, Pd, Se 10-1 ～ 10-2 MgO JCPDS # 77-2364 (3) After leaching 10-2 ～ 10-3 Pt, Au, Rh, 　・・・ Mg2V2O7 JCPDS # 70-1163 Resources and production Application V metal 20 40 60 80 Angle, 2θ (degree) 20 30 40 50 60 70 80 Angle, 2θ (degree) The periodic table of the elements A A B B B B B B A A A A A A A A Ⅰ Ⅱ Ⅲ Ⅳ Ⅴ Ⅵ Ⅶ Ⅷ Ⅰ Ⅱ Ⅲ Ⅳ Ⅴ Ⅵ Ⅶ Ⅷ Hydrogen Helium H He 1 2 Lithium Beryllium Boron Carbon Nitrogen Oxygen Fluorine Neon Li Be B C N O F Ne 3 4 5 6 7 8 9 10 Sodium Magnesium Aluminium Silicon Phosphorus Sulfur Chlorine Argon Na Mg Al Si P S Cl Ar 11 12 13 14 15 16 17 18 Potassium Calcium Scandium Titanium Vanadium Chromium Manganese Iron Cobalt Nickel Copper Zinc Gallium Germanium Arsenic Selenium Bromine Krypton K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 Rubidium Strontium Yttrium Zirconium Niobium Molybdnum Technetium Ruthenium Rhodium Palladium Silver Cadmium Indium Tin Antimony Tellurium Iodine Xenon Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te Xe I 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 54 53 Caesium Barium Lutetium Hafnium Tantalum Tungsten Rhenium Osmium Iridium Platinum Gold Mercury Thallium Lead Bismuth Polonium Astatine Radon Alloying process Fe－V alloy Cs Ba Lu Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn 55 56 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 Francium Radium Lawrencium Rutherfordium Dubnium Seaborgium Bohrium Hassium Meitnerium V2O5 (s) + Al (s) ( + Fe (s)) Fr Ra Lr Rf Db Sg Bh Hs Mt 87 88 103 104 105 106 107 108 109 Electron beam melting V metal Preform reduction process (PRP) Reduction process (1) After calcination CaV2O4 CaO Ca2V2O7 (2) After reduction Intensity, I (a.u.) (3) After leaching 20 40 60 80 Angle, 2θ (degree) Commercial production process Special steel Confirmed reserve Ores production Vanadium? Aluminothermic process In the primary use, vanadium is consumed as an alloy element of steel. 3 V2O5 (s) + 10 Al (s) (+ Fe (s)) → 6 V (in Al (l)) + 5 Al2O3 (s) (Fe-V-Al (l)) High thermal stability and tensile strength V2O5 production Fe-V production Table Abundance of elements in the earth’s crust. 15 ～ 25 mass% Al (Ref. Iron and Steel Institute of Japan) Features Ti-V hydrogen storing alloy ◎ Simple and economic process ○ First batch type process with rich scalability × Difficult to control the purity × Repeated removal of Al by the electron beam melting for some applications Vanadium has high hydrogen storage ability. Ti-V alloy draws attention as a negative electrode material of nickel hydride battery, and has a potential to be used for lower-cost and higher-capacity battery. Vanadium production in Japan Table Amount of production and price of some metal elements in 2007. Feature of vanadium 　・ Low density(6.11 g/cm3) and high melting point (2188 K). 　・ The 20th largest crustal abundances among the all elements. 　・ Average abundance of vanadium in the earth’s crust; 120ppm. (cf. Common (or base) metals such as Ni: 84ppm, Cu: 60ppm, Zn: 70ppm, Pb: 14ppm). Amount of production Price Element (103 ton / year) ($ ・ kg-1) Aim of this study V 58 39 It is important to develop a new production process of pure vanadium metal and vanadium alloy. 1,100,000 Fe 0.06 Development of simple and low-cost process for high purity vanadium metal or alloys 29,000 Al 3 15,000 Cu 7 1,600 Ni 40 Zn 11,000 3 (Ref. Matsushita Electric Industrial Co., Ltd) Thermodynamic analysis Features Flowchart of our process Vapor pressure of metals V2O5 + 5 R → 2 V + 5 ROx ◎ Suitable for uniform reduction ◎ Flexible scalability ○ Possible to control the morphology of the powder by varying the flux content in the preform ○ Possible to prevent the contamination from the reaction container and to control the purity ○ Amount of waste solution is minimized. ○ Molten salt as a flux can be reduced in comparison with the other direct reduction process. × Difficult to produce reductant and to control its vapor 0 Mg V2O5 Flux Binder -4 -5 Ca MxOy＋ Flux ＋ Binder Preform Mixing / casting -10 Fe Vapor pressure log p° (atm) -15 Ti Feed preform V -20 Tcal. =873 K → 1173 K Calcination -25 tcal. = 2 hr 1173 K 1273 K PRP is simple and low-cost process for high purity products. Casting -30 Forming Reduction by reductant vapor Sintered preform 800 900 1000 1100 1200 1300 Reductant (Ca, Mg) Temperature, T / K m.p.(V2O5) 963 K Reaction temperature Tred. =1273 K Reduction Problem The melting point of vanadium pentoxide (V2O5) is low (963 K), and it is difficult to fabricate mechanically strong solid preform. Reduction has to be carried out at temperature higher than 1173 K to maintain enough vapor pressure of Ca or Mg. tred. = 6 hr TIG welding Ellingham diagram of oxides Stainless steel cover 0 Reduced preform 50 % CH3COOH aq., 1173 K 1273 K Stainless steel reaction vessel -200 3/2 Fe + O2 = 1/2 Fe3O4 20 % HCl aq., -400 Leaching and rinsing Distilled water, Feed preform (V2O5, Flux) 4/5 V + O2 = 2/5 V2O5 Waste solution Liquid -600 Solid Isopropanol, Standard Gibbs energy of formation, DGﾟf /kJ mol-1 Ti + O2 = TiO2 CaO or MgO was added to feed preform in order to synthesize complex oxides (CaxVyOz,MgxVyOz) during calcination. The obtained feed preform has a mechanical strength at elevated temperature and suitable for handling during processing. Acetone -800 Stainless steel holder 2 Mg + O2 = 2 MgO Vacuum drying Reductant (Ca, Mg) -1000 2 Ca + O2 = 2 CaO Ti sponge getter -1200 V metal powder -1400 800 1100 900 1000 1200 1300 Temperature, T / K Weight change of the samples X-ray fluorescence spectrometry The feasibility of the preform reduction process (PRP), based on the thermal reduction of V2O5, was demonstrated. ・ Complex oxide containing V2O5 was synthesized by the calcination process in order to increase the mechanical strength of feed preform. ・ Vanadium powder with 99.7 mass% purity was obtained by magnesiothermic reduction of feed preform. Calcination process Table Experimental condition and mass of samples after each step. Table Analytical results of vanadium powder obtained by PRP. Mass of sample after calcination, w1 / g Mass of sample after reduction, w2 / g Mass of sample after leaching, w3 / g Mass of preform, wpre / g V2O5 + 3CaO V2O5 + 3MgO Mass of reductant, wR / g Ca Mg Composition of sample (mass%) X-ray diffraction pattern Appearance Ex. # Reductant Flux Flux Reductant Ex. # Ca Mg V Fe Cr Ca CaO Ca CaO 4.537 3.976 3.474 3.642 1.805 ex.1 ex.1 79.0 20.4 － 0.1 0.4 Ca MgO 4.226 4.906 3.670 3.955 0.981 Ca MgO ex.2 ex.2 85.4 13.0 － 0.3 0.5 Mg CaO Mg CaO 4.478 2.573 3.604 4.435 1.071 86.0 2.4 10.6 0.2 0.5 ex.3 ex.3 Mg MgO 4.158 3.345 5.086 0.729 Mg MgO 3.937 ex.4 99.7 － 0.2 0.01 0.03 ex.4 aDetermined by XRF ; value excludes carbon and gaseous elements. Condition for reduction ・Temperature :1273 K, Time : 6 hr X-ray diffraction pattern ex.4 Flux : MgO, Reductant : Mg ex.1 Flux : CaO, Reductant : Ca Condition for calcination The calcination temperature was raised from 873 K to 1173 K during 2 hr of calcination period. ・When using Mg vapor as a reductant, pure vanadium metal was obtained. The purity of the obtained vanadium powder was 99.7 mass%. ・When using Ca vapor as a reductant, Ca2V2O7 in thepreform was reduced to CaV2O4 after reduction. At this stage, vanadium metal was not obtained. ・ Investigation of residual oxygen concentration, and evaluation of total vanadium yield. ・ Development of production process of Ti-V alloys. ・ Analysis of reduction mechanism by utilizing the chemical potential diagram for the system involving oxygen, calcium, magnesium, and vanadium. ・ Complex oxides (Ca2V2O7 or Mg2V2O7) was synthesized after calcination. ・ Calcined sample maintained its shape form. The reason for incomplete reduction when using Ca vapor is not well understood. The difference of the results between Mg and Ca reductant is partially due to the difference of their vapor pressure. The vapor pressure of Mg (0.458 atm) is 26 times larger than Ca (0.018 atm) at 1273 K. →　This can be used as a feed preform for reduction experiment.