Extractive Met RE

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    Extractive Metallurgy of

    the Rare EarthsFathi Habashi

    Department of Mining, Metallurgical, andMaterials Engineering

    Laval University, Quebec [email protected]

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    Rare Earths in the Periodic Table

    Pr Nd Pm Sm Eu Gd Tb D y Ho Er Tm Yb LuLa Ce57 58 59 60 61 62 63 64 65 66 67 68 69 70 71

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    1 2

    H He3 4 5 6 7 8 9 10

    Li Be B C N O F Ne11 12 13 15 16 17 18

    Na g Al Si P S Cl Ar19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36

    K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54

    Rb Sr Y Zr Nb Mo Tc Ru Rh Pd g Cd In Sn Sb Te I Xe55 56 57 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86

    Cs Ba a Hf Ta W Re Os Ir Pt Au g Tl Pb Bi Po At Rn87 88 89

    Fr Ra c

    58 59 60 61 62 63 64 65 66 67 68 69 70 71

    Ce Pr Nd Pm Sm Eu Gd Tb y Ho Er Tm Yb Lu90 91 92 93 94 95 96 97 98 99 100 101 102 103

    Th Pa U p Pu Am Cm Bk Cf Es Fm Md No Lw **Actinides

    INNER TRANSITION METALS

    PERIODIC TABLEMonatomic

    LESS TYPICAL

    *Lanthanides

    Vertical & Horizontal

    METALS

    MET LLOI S

    m ar ty

    MET LS NONMET LS

    Vertical Similarity

    CovalentTRANSITION METALS

    Horizontal Similarity

    TYPICAL METALS

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    RAW MATERIAL

    Monazite and xenotime: phosphates

    Bastnasite: fluorocarbonate

    Phosphate rock

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    Other complex minerals

    Euxenite (Y,Ce)(Nb,Ta,Ti)2O6 Samarskite (Y,Ce)4(Nb,Ta,Ti)2O6 Fergusonite (Y)(Nb,Ti,Ta)O4 Betafite (U,Ca,Y,Ce2(Nb,Ta,Ti)2O6(OH)

    Pyrochlor (Na,Ca,Ce)2(NbTa,Ti)2(O,OH,F)7

    Loparite (Na,Ca, Ce)2(Nb,Ta,Ti)

    2O

    6

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    Rare earths in China

    [1] Associated with iron ore in Baotou, Inner

    Mongolia Autonomous Region, northern

    China

    [2] Associated with clay in Guandzhou,

    Guandong Province in southern China

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    Home of rare earths welcomes you

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    Relative abundance

    Rare earths 10-4 %

    Similar to arsenic, antimony, molybdenum,

    tungsten, beryllium, tantalum, and

    germanium

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    Monazite and Xenotime

    The minerals monazite and xenotime are lanthanidephosphate containing some thorium and small amountsof uranium. They differ slightly in crystal structure andthe individual lanthanides occur in different proportions.

    Monazite is widely distributed in the Earths crust andoccurs in small proportions in granites. When such rocksare weathered, grains of monazite are carried by waters,then deposited at the mouths of rivers, together with theheavier constituents of the parent rock, to form black

    sands. Monazite occur mainly in Brazil, India, Australia, and

    USA, xinotime occurs mainly in South East Asiaassociated with alluvial tin deposits.

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    Physical properties of lanthanide minerals

    Monazite Xinotime

    Color Yellow to red

    brown

    Pale yellow to

    brownish green

    Specific gravity 4.95.5 4.54.6

    Hardness, Mohs 5 4.5

    Crystal structure Monoclinic Tetragonal

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    Lanthanide

    oxide

    Monazite

    %

    Xenotime

    %

    Bastnasite

    %

    Light La2O3CeO2Pr6O11Nd2O3

    23.0

    46.5

    5.1

    18.4

    93

    0.5

    5.0

    0.7

    2.2

    8.4

    32.0

    49.0

    4.4

    13.5

    98.9

    Heavy Sm2O3Eu2O3Gd2O3Tb4O7Dy2O3Ho2O3

    Er2O3Tm2O3Yb2O3Lu2O3Y2O3

    2.3

    0.07

    1.7

    0.16

    0.52

    0.09

    0.130.013

    0.061

    0.006

    2

    7

    1.9

    0.2

    4.0

    1.0

    8.7

    2.1

    5.40.9

    6.2

    0.4

    60.8

    91.6

    0.5

    0.1

    0.3

    0.01

    0.03

    0.01

    0.010.2

    0.01

    0.1

    0.1

    1.37

    Composition of lanthanides in monazite, xenotime, and bastnasite

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    RECOVERY: Monazite, xenotime

    Monazite

    concentrate

    Digestion

    H2SO4

    Dissolution

    Filtration

    Residue

    SiO2TiO2ZrSiO4

    Leaching

    NaOH

    Filtration

    Crystallization Na3PO4 10H2O

    Residue :

    hydroxides of

    U, Th, R.E.

    Monazite

    concentrate

    H2O

    Solution

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    Acid method:

    2LnPO4+ 3H2SO4 Ln2(SO4)3+ 2H3PO4

    Alkali method:LnPO4+ 3NaOH Ln(OH)3+ Na3PO4

    Hydroxides of uranium, thorium, and

    lanthanides, containing small amounts ofphosphate; it is dissolved in acid for furtherseparation.

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    Bastnasite

    Bastnasite is a fluorocarbonate:

    Ln2(CO3)3, LnF3

    or LnFCO3.

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    Bastnasite

    In the Molycorp process, the mineral is

    concentrated to 60% by flotation and thencalcined, converting the cerium to the

    tetravalent state.

    It is then treated with hydrochloric acid,

    which causes only the trivalent rare earth

    elements to go into solution, leavingbehind 6580% CeO2

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    Bastnasite

    The scheme of separation of the lanthanides from leachsolution of bastnasite concentrates by extraction withD2EHPA.

    Cerium is already separated in the leaching step since it

    is transformed into soluble cerium(IV) compound and isrecovered from the residue.

    Each extraction step includes numerous stages ofcontact with the extractant and the stripping agent undercertain conditions of organic/aqueous ratio, and

    extractant and stripping agent concentrations. The plant is computerized and is fully automated.

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    MolyCorp process

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    Production

    Tonnage wise, phosphate rock is the most

    important source of rare earths as

    compared with the other material.

    About 18 million tons of igneous rock are

    treated annually while only 30 000 tons of

    monazite and xenotime.

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    During the manufacture of phosphoric acidabout 70% of the rare earths is lost in thegypsum.

    However, if acidulation is conducted by nitric

    acid all will go into solution and can berecovered by organic solvents.

    In Finland, the lanthanides were recoveredcommercially by Kemira Oy from phosphate rock

    during 19651972 using organic solvents. It is believed that a similar operation is inexistence in Russia.

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    Nitric acid leaching

    Norsk Hydro

    BASF

    Etc. ================================

    Can be conducted in heaps

    ================================

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    New separation technology

    No more fractional crystallization

    Ion exchange

    Solvent extraction

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    Rare earths and nuclear reactors

    Rare earths arefission products

    [atomic weight140]

    They absorbneutrons andmust be removed

    Ce 144 product ofatomic bombs

    [t 285 days]

    N f th

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    New uses of rare earths

    TV screens

    Special magnets

    Special alloys

    Catalysts

    ElectronicsGlass and ceramics

    h k

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    Thank

    s

    athi Habashi