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2011. Materials Preparation Center A US Department of Energy Specialized Research Center. High Purity Rare Earth Metals Preparation. Trevor M. Riedemann Manager, MPC Rare Earth Materials Section 122 Metals Development Building Ames Laboratory Ames, IA 50011-3020 Phone: 515-294-1366
2011 Materials Preparation CenterA US Department of Energy Specialized Research Center High Purity Rare Earth Metals Preparation Trevor M. Riedemann Manager, MPC Rare Earth Materials Section 122 Metals Development Building Ames Laboratory Ames, IA 50011-3020 Phone: 515-294-1366 Fax: 515-294-8727 E-mail: email@example.com
Acknowledgements The Materials Preparation Center (MPC) is a U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, Division of Materials Sciences & Engineering specialized research center located at the Ames Laboratory. MPC operations are primarily funded by the Materials Discovery, Design, & Synthesis team's Synthesis & Processing Science core research activity. Thomas A. Lograsso Division Director Division of Materials Science & Engineering 124 Metals Development Building Ames, IA 50011-3020 Phone: 515-294-8425 Fax: 515-294-8727 E-mail: firstname.lastname@example.org Lawrence L. Jones Director, MPC 121 Metals Development Building Ames Laboratory Ames, IA 50011-3020 Phone: 515-294-5236 Fax: 515-294-8727 E-mail: email@example.com
Acknowledgements The Rare Earths, F.H Spedding & A.H. Daane, eds. (1961) John Wiley & Sons. Chapter 6 – Preparation of the Rare Earth Fluorides, O.N. Carlson & F.A. Schmidt Chapter 8 – Metallothermic Preparation of Rare Earth Metals, A.H. Daane Beaudry, B.J. & P.E. Palmer, (1974) “The use of inert atmospheres in the preparation and handling of high purity rare earth metals” Haschke, J.M, and H.A. Eich, eds. Proceedings of the 11th Rare Earth Research Conference (CONF-741002, Part 2, NTIS, Springfield, Virginia 22151) pp 612-620 Handbook on the Physics and Chemistry of Rare Earths, Vol 1 – Metals, (1978) K.A.Gschneidner, Jr. & L.R. Eyring, eds. Chapter 2 – Preparation and Basic Properties of the Rare Earth metals, B.J. Beaudry & K.A. Gschneidner A Lanthanide Lanthology, Part I & II, B.T. Kilbourn (1993) Molycorp. Inc.
The Rare Earths - A very Brief History 1794 J. Gadolin first reports their existence 1804 M.H. Klaproth isolated ceria 1827 Preparation of first REM (Ce) … 1931 Preparation of “reasonably pure” metal by electrolysis 1937 Pure enough to determine crystal structures 1947 Separation adjacent RE by ion exchange. 1950’s Spedding and Daane – developed “Ames Process” 1787 – 1987 Two Hundred Years of Rare Earths Rare Earth Information Center IS-RIC 10 Institute for Physical Research and Technology Iowa State University K.A. GschneidnerJr& J. Capellen,ed.
The Rare Earths - Etymology Z Symbol Name Etymology 21 Sc Scandium Latin Scandia (Scandinavia) • Y Yttrium Ytterby, Sweden, where the first ore was discovered. 57 La Lanthanum Greek "lanthanein", meaning to be hidden. 58 Ce Cerium For the dwarf planet Ceres. 59 Pr Praseodymium Greek "prasios” leek-green, &"didymos", meaning twin. 60 Nd Neodymium Greek "neos” new, and "didymos", meaning twin. 61 Pm Promethium Titan Prometheus, who brought fire to mortals.62 Sm Samarium VasiliSamarsky-Bykhovets, who discovered samarskite. 63 Eu Europium For the continent of Europe. 64 Gd Gadolinium Johan Gadolin (1760–1852), to honor his study of REE. 65 Tb Terbium Ytterby, Sweden. 66 Dy Dysprosium Greek "dysprositos", meaning hard to get. 67 Ho Holmium Stockholm (in Latin, "Holmia”) 68 Er Erbium Ytterby, Sweden. 69 Tm Thulium For the mythological northern land of Thule. 70 Yb Ytterbium Ytterby, Sweden. 71 Lu Lutetium Lutetia, the city which later became Paris. 1787 – 1987 Two Hundred Years of Rare Earths Rare Earth Information Center IS-RIC 10 Institute for Physical Research and Technology Iowa State University K.A. GschneidnerJr& J. Capellen,ed.
The Rare Earths - Abundance US Geological Survey Fact Sheet 087-02 Rare Earth Elements – Critical Resources for High Technology Gordon B. Haxel, James B. Hedrick, and Greta J. Orris
High Purity Oxide Prices Y2O3 La2O3 CeO2 Pr6O11 Nd2O3 Sm2O3 Eu2O3 Gd2O3 Tb4O7 Dy2O3 Ho2O3 Er2O3 Tm2O3 Yb2O3 Lu2O3 III / IV III / IV III / IV UPDATE ON THE GLOBAL RARE EARTH INDUSTRY: Prospect for Magnetic Rare Earth Materials 2004 China Magnet Symposium Global Markets and Business Opportunities May 17-21, 2004, Xi’an, China Constantine E. Karayannopoulos
High Purity Oxide Prices Y2O3 La2O3 CeO2 Pr6O11 Nd2O3 Sm2O3 Eu2O3 Gd2O3 Tb4O7 Dy2O3 Ho2O3 Er2O3 Tm2O3 Yb2O3 Lu2O3 2004200720082009 11/2010 La 99% US$/kg 1.60 3.10 7.75 6.25 61.00 Ce 99% US$/kg 1.57 2.50 4.35 4.50 49.00 Pr 99% US$/kg 7.44 28.00 27.00 14.00 72.00 Nd 99% US$/kg 5.64 29.00 27.00 14.00 77.00 Eu 99% US$/kg 292.00 300.00 475.00 450.00 630.00 Tb 99% US$/kg 341.00 555.00 650.00 350.00 605.00 Dy 99% US$/kg 31.00 85.00 110.00 100.00 295.00 III / IV III / IV III / IV Source: Metal Pages
The Rare Earths - Ames Process • High purity oxides from Ion-Exchange (2) Preparation of anhydrous RE-fluorides (3) Metallothermic reduction by Ca metal (4) Metallothermic reduction by La metal R2O3 + 6HF 2RF3 + 3H2O 3Ca + 2RF3 2R + 3CaF2 R2O3 + 2La La2O3 + 2R
Ames Process = High purity ? Cross Contamination in Processing Line Impurity Sources: Oxygen: Incomplete oxide conversion Calcium reductant Atmosphere (handling and processing) N, C, & H: Adsorbed on oxide/fluoride Calcium reductant Tantalum Crucible Atmosphere Ca & F: Reductant and incomplete reduction (10% excess Ca is used in Rx) Insufficient vacuum casting Fe, Co, Ni & Cu: Tantalum Crucible Impurities in oxide & HF Contamination of oxide during handling Foundry vs Chip Fab
How Pure? Ames Commercial 150 175 555 660 3105 2100 N/T 99.996 99.99 99.99 99.96 99.9 99.2
Anlaysis of three commercial Tb samples and MPC Tb (ppm at). Source A Source D MPC Impurity Ingot DistilledDistilled Distilled H 7400 6800 22200 945 C n.a. n.a. n.a. 132 N 810 8000 1070 91 O 10900 28800 34400 665 Fe 156 117 60 14 La 200 120 35 1 Ta 5000 9 0 11 Total mag. RE 68 86 112 17 at% pure <97.5 <95.6 <94.2 <99.81 Semiquantitative MS for 25 elements (H,N and O by vacuum fusion) High purity Rare Earth Metals – Do We Need Them? Proc. of the first Symposium Rare Metals Forum, Extra-High Purification Technology and New Functional Materials Creation of Rare Earth Metals, Society of Non-Traditional Technology, Tokyo, Japan (1989) pp 13-29 K.A. Gschneidner, Jr.
Why do we need High Purity Metals? Impurities affect the basic properties of pure metals (and alloys) Lattice parameters Crystal structure Melting point Hardness Strength Resistivity Susceptibility Grain growth Magnetic domain wall motion Stoichiometry of alloy is shifted Second phase can form and change the properties. Crystal Growth Oxygen as impurity in crystal growth of intermetallics, D. Souptel, W. Lo¨ ser, W. Gruner, G. Behr, Journal of Crystal Growth 307 (2007) 410–420 Impurities may mask the INTRINSIC behavior of the pure metal or alloy material
Why do we need High Purity Metals? V. K. Pecharsky and K. A. Gschneidner, Jr. Giant Magnetocaloric Effect in Gd5Si2Ge2 Physical Review Letters 78 (1997) No. 23 T. Zhang , et. Al (Sichuan University) The structure and magnetocaloric effect of rapidly quenched Gd5Si2Ge2alloy with low-purity gadolinium Materials Letters 61 (2007) 440–443 K. A. Gschneidner, Jr., et al. Method of Making Active Magentic Refrigerant, Colossal Magnetostriction and Giant Magentoresistive Materials Based on Gd-Si-Ge Alloys US Patent: 6,589,366 B1 (2003) -ΔSm(J/kg K) Impurities are suppressing a structural transition from orthorhombic to monoclinic Gd5Si2Ge2: 0 – 5 T Temperature (K)
Why do we need High Purity Metals? Y. Matsumoto,et al. Quantum Criticality Without Tuning in the Mixed Valence Compound -YbAlB4. Science, 2011; 331 (6015) S. Nakatsuji, et al. Superconductivity and quantum criticality in the heavy-fermion system –YbAlB4 Nature Physics 4, 603 - 607 (2008) Robin T. Macaluso, et. al Crystal Structure and Physical Properties of Polymorphs of LnAlB4 (Ln = Yb, Lu) Chem. Mater., 2007, 19 (8), pp 1918–1922 An exotic new superconductor based on the element ytterbium displays unusual properties that could change how scientists understand and create materials for superconductors and electronics. Beta-YbAlB4, can reach a quantum critical, without being subject to massive changes in pressure, magnetic fields, or chemical impurities.
Inputs: Oxides High Purity Oxides Y2O3 La2O3 CeO2 Pr6O11 Nd2O3 Sm2O3 Eu2O3 Gd2O3 Tb4O7 Dy2O3 Ho2O3 Er2O3 Tm2O3 Yb2O3 Lu2O3 III / IV III / IV III / IV GARBAGE IN = GARBAGE OUT Praseodymium Oxide Pr6O11 99.999% pure <10 ppm REM
Inputs: Calcium Reductant Triple Distilled commercial Ca has ~2000 – 5000 ppm oxygen
Distilled under He pp to remove oxygen Distilled under He ppto remove oxygen 6 Days 900 g/run Ce 1900g Ca Lu 505g Ca • Oxygen content is lowered <10 ppm • Glove box protected • Ca readily picks up O from H2O • >1000 ppm from air in 5 minutes • The effect of handing the Ca in air results in a 30-fold increase in O content in Cerium metal (BJB)
Inputs: Tantalum 10” x 14” x 0.030” = $1081.00 X Alumina Magnesia Quartz Zirconia Graphite Iron X X X X X
Inputs: Tantalum ASTM B708 – 05R05200, unalloyed tantalum, electron-beam furnace or vacuum-arc melt, or both ASTM B708 – 05R05400, unalloyed tantalum, powder-metallurgy consolidation Element R05200 R05400 C 0.010 0.010 O 0.015 0.03 N0.010 0.010 H0.0015 0.0015 Fe 0.010 0.010 Mo0.020 0.010 Nb0.100 0.010 Ni0.010 0.010 Si0.005 0.010 Ti 0.010 0.010 W 0.05 0.010 Cleanest Ta: Pickled Annealed 2000ºC degassed
Inputs: Hydrofluoric Acid (HF) Purity range from 99% to 99.99% Parameter Level † HF 99.95 wt% H2SO4 100 wt ppm SO2 50 wt ppm H2O 200 wt ppm As 25 wt ppm Hydrofluosilicic0.05 mol %* †Honeywell Specifications *Handbook of Compressed Gasses, 4th ed. (1999) H2SiF6 Nasty Stuff Not a lot of impurities to worry about…but…..
The Rare Earths - Physical Properties 1 2 3 4 Vapor Pressure at Melting Point Tm 73.4 mm Hg Ce 3.6(10)-12 mm Hg
Ames Process – Flow Diagram 1 4 2 3
Ames Process – Flow Diagram • Sm, Eu, Tm and Yb • Low Boiling Points • Reduction by Lanthanum from Oxide • Easily purified by Sublimation • Sm, Eu, Tm and Yb can be melted in Ta crucibles without Ta contamination • Tm is very difficult to arc melt due to ~74mm vapor pressure at its melting point
Ames Process – Procedure • Sm, Eu, Tm and Yb • Dry Oxide Removes H2O and CO2 • Machine lanthanum chips • Mix oxide and La chips (in dry box) • Pack in crucible (in dry box) • Load into induction furnace • Heat under vacuum. • Hold for 8 hours • Perform a low temp sublimation. • Strip Ta from sublimate mass • Europium is extruded.
Ames Process – Flow Diagram • La, Ce, Nd and Pr • Low Melting but high Boiling Points • Volatile impurities (Ca & F) can be quantitatively removed by vacuum casting without loss of metal • Ta solubility at M.P. is low therefore Ta dissolved during vacuum casting can be removed by precipitation.
Ames Process – Procedure • La, Ce, Nd and Pr • Dry Oxide • LT/HT Fluorination of oxide • Heat mixture of Ca& REF3 • Cool, remove slag • Total of three reductions in same crucible • Vacuum cast at high temperature • Cool to just above melting point. • Hold to precipitate tantalum • Decant or “pour” RE into thin wall crucible • Machine off crucible • Arc cast into ingots
Ames Process Reduction Step
Ames Process Post Reduction
Ames Process Pour/Decant Step
Ames Process – Flow Diagram • Sc, Dy, Ho and Er • High Melting and low to intermediate Boiling Points. • To remove F impurity thru vacuum casting, must loose up to 30% of metal • Easily purified with respect to O, N, C, Ta and other non-volatile impurities by sublimation.
Ames Process – Procedure • Sc, Dy, Ho and Er • Dry oxide • LT Fluorination of oxide • Heat mixture of Ca& REF3 • Cool, remove slag • Total of three reductions in same crucible • Excluding Sc • Vacuum cast Metal loss occurs • Sublimate to purify • Machine off crucible • Arc cast into ingots
Ames Process Reduction Step
Ames Process Sublimation Step
Ames Process – Flow Diagram • Y, Gd, Tb and Lu • High Melting and High Boiling Points. • Volatile impurities (Ca & F) can be removed by vacuum casting without significant loss of metal • Ta solubility at MP is high, but can be removed by distillation. • Slow distillations will reduce O, N, C slightly
Erosion of Ta by Refluxing During Distillation Scandium At MP ~ 3.2 at.% Ta (11.8 wt%) Cerium, At MP ~ 0.10 at% Ta
Ames Process – Flow Diagram Hey! What about me!
High Purity Fluorides YF3 LaF3 CeF3 PrF3 NdF3 SmF3 EuF3 GdF3 TbF3 DyF3 HoF3 ErF3 TmF3 YbF3 LuF3 Praseodymium Fluoride PrF3 “Topped”
High Purity Fluorides 450ºC Commercial: R2O3 + 6NH4HF2 2RF3 + 3NH3 + 3H2O • 1000 to 5000 ppm residual O • Also a source of N impurity 650ºC R2O3 + 6HF(anhydrous) + Ar 2RF3 + 3H2O + Ar Ames LT: • 10 to 1000 ppm residual O • Pt lined furnace eliminated source of transition metal impurities. M.P. RF3 + HF(anhydrous) RF3 + H2O Ames HT “Topped”: • <10 ppm residual O • Some reduction of transition metals La – Nd, Gd, Tb, Lu
High Purity Fluorides M.P. RF3 + HF(anhydrous) RF3 + (H2O, other trace) Metal T Al Si Cr Fe Ni Cu La - 20 60 9.5 66 15 2.9 Yes 0.5 3 0.1 15 1.0 0.5 Ce - 4.0 30 1.1 40 105.1 Yes 0.5 <9 0.6 10 6.6 2.6 Tb - 2 10 1 19 4 3.6 Yes 0.5 <0.20.31835.0 Beaudry, B.J. & P.E. Palmer
Oxygen content in AT PPM of selected REM prepared from various grades of fluorides and calcium. La CePrNdGd Tb Lu Y (1) 7800 5020 7000 9000 12770 27500 (2) 3040 2900 2500 2700 (3) 3040 3070 (4) 204 260 254 480 735 745 1145 2170 (5) 304 130 260 307 245 440 430 145 (1) Typical commercial purity (2) Fluoride prepared by NH4HF2 and reduced with purified calcium (3) Topped fluoride, purified calcium, handled in air (4) Low-temp fluoride, purified calcium, handled in glove box (5) Topped fluoride, purified calcium, handled in glove box Beaudry, B.J. & P.E. Palmer