Quiz 22 OCT 08

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Quiz 22 OCT 08
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• A process developed to treat minerals containing
  4000 ppm of tetravalent uranium (UO2) is based on
  the following conditions
• Consumption of H2SO4 25 kg/t
• Consumption of NaClO3 2 kg/t
• Volume of attacking solution/ mineral mass 1
  m3/t
• This treatment is used to solubilize 96 of
  uranium content.

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• You are asked to
• Write the oxidation equation of U(IV) by ClO3-
  ions
• Determine the efficiency of the oxidizing
  treatment
• Determine the composition in uranium and H2SO4,
  of the solutions after attack (by making the
  following hypothesis that the variation of H
  is negligible during the reaction period)

4

• The purification of uranium is performed by
  chromatography on anion exchange resins columns (
  with an exchange capacity for one monovalent ion
  3 eq/kg)
• Determine, by using Figure 1, the distribution
  coefficient of U(VI) between the attacking
  solution and the resin ( consider that an excess
  of resin is used per unitary volume of solution)
• Determine the volume of uraniferous solution that
  you can transfer on a column composed of 100 kg
  of resins where we want to saturate to 70
  maximum the exchange sites, knowing that the
  extraction reaction is
• The extraction of 1 U(VI) is saturating 4 sites
  of the resin

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Distribution Ration KD
Concentration (NH4)2SO4 or H2SO4 in Mol/L
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CORRECTION

• Write the oxidation equation of U(IV) by ClO3-
  ions

OXIDATION
REDUCTION
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Determine the efficiency of the oxidizing
treatment (1)

• Number of moles of U solubilized
• 4000 ppm of U is equal to 4000 g/t of U
• Knowing that the molar mass M of U is 238 g /
  mole, 4000g of U represents 4000/238 16.8067
  moles/t. Since 96 of U is solubilized, we will
  have 0.9616.8067 16.13 moles/t of U
  solubilized.
• Number of moles of NaClO3 used
• M of NaClO3 is 106.5 g/mole
• Consumption is 2 kg/t, 2000g/t 2000/106.5
  18.78 moles/t

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Determine the efficiency of the oxidizing
treatment (2)

• Number of moles of NaClO3 necessary to the
  process
• After Eq 1, 1 mole of NaClO3 reacts with 3 moles
  of UO2
• If we have 16.13 moles of U, we need 16.13/3
  5.37 moles of NaClO3
• The efficiency will be 5.37/ 18.78 0.286

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Composition Solution

• Uranium
• Mass of U solubilized
• 4000 g 96 3840g/t or 3.840g/L, knowing that
  the volume is 1 m3 1000L.
• U is 3.840/238 0.016M/L
• H2SO4
• 25kg/t 25000g/t or 25 g/L, knowing that the
  volume is 1 m3 1000L.
• M 98g/mole
• H2SO4 25/98 0.255moles/L

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Distribution Coefficient
H2SO4 0.25M Kd U(VI) 200
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Volume of the uraniferous solution

• Exchange capacity of the resin
• 3 eq/kg 100 kg of resin 300 eq/kg in
  monovalent ion
• In uranium we will have 300/4 75 moles of
  U/column
• The saturation is 70 so 7570 52.5 moles of U
• The total volume of the uraniferous solution is
• 52.5 moles/0.016 3254.8 liters