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Application of titration techniques for analysis of hydrometallurgical solutions

Application of titration techniques for analysis of hydrometallurgical solutions. By Volha Bazhko Senior Scientist. reliable results even in field condition s . Titration. Advantages of titration methods : Do not require complicated and expensive equipment Simple and fast method

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Application of titration techniques for analysis of hydrometallurgical solutions

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  1. Application of titration techniques for analysis of hydrometallurgical solutions By Volha Bazhko Senior Scientist reliable results even in field conditions

  2. Titration Advantages of titration methods: • Do not require complicated and expensive equipment • Simple and fast method • Reliable results even under plant conditions

  3. Titration Types of titration: • Acid-base titration • determination of acidity of solutions • determination of alkalinity of solutions • neutralisation tests • titration of mixtures of acid • Precipitation titration • determination of Cl- • determination of CN- • determination of S2O32-

  4. Titration Types of titration: • Complexometric titration • determination of base metals with EDTA • Redox titration • determination of base metals and PGMs • dissolved O2, H2O2 and anions • determination of the oxidation state of Fe, Mn and other elements in solution

  5. Milled ore Co bleed product H2SO4 Fe2+ / Fe3+ Leach SO2 1 tails 2 3 S/L Cu SX 5 4 Cu EW Cu0 • PLS (Fe2+, Fe3+ and acid titration) • SX feed (Fe, Cu2+ and acid titration) • SX raffinate (Cu2+, Fe2+, Fe3+ and acid titration) • Advanced electrolyte (Cu2+ and acid titration) • Spent electrolyte (Cu2+ and acid titration) • Cu/Co processing

  6. SO2, Fe2+ and Fe3+ determination • Titration1: Back dichromatometric titration of the amount of Fe2+ and SO32-: 6 Fe2+ + Cr2O72- + 14 H+ = 2 Cr3+ + 6 Fe3+ + 7 H2O • 3 SO32-+ Cr2O72- + 8 H+ = 2 Cr3+ + 3 SO42- + 4 H2O • Mixed acid (H2SO4+ H3PO4) • Indicator: diphenylamine. • Titration 2: Fe3+ titration with EDTA. pH < 2 Indicator: sulphosalicylic acid

  7. Titration 3: Total iron determination with EDTA. Pre-oxidation of Fe2+ with H2O2 pH < 2 Indicator: sulphosalicylic acid CFeIII (mol/L) = CEDTA * V2 / Vsample CFeII (mol/L) = CEDTA * (V3 - V2) / Vsample CSO2(mol/L) = 3(CK2Cr2O7 * VK2Cr2O7 – - (CFeSO4 * V1 + CEDTA * (V3 - V2)) / 6 ) / Vsample SO2, Fe2+ and Fe3+ determination

  8. Cu and Fe determination • 1 Titration: Determination of the amount of copper and iron • Fe2+ pre-oxidation • Reduction of Fe3+ and Cu2+ with excess of KI Fe2(SO4)3 + 2 KI = 2 FeSO4 + K2SO4 + I2 • 2CuSO4 + 4 KI = 2 CuI↓ + 2 K2SO4+ I2 • Titration of I2 liberated I2+ 2 Na2S2O3 = Na2S4O6 + 2 NaI Indicator: starch. Fe3+ can be masked by addition of fluoride.

  9. Cu and Fe determination • 2 Titration: Determination of copper • Masking of Fe3+ with fluoride • Reduction of Cu2+ with excess of KI • Titration of I2 liberated • CCu (mol/L) = CNa2S2O3 * V2 / Vsample • CFe (mol/L) = CNa2S2O3 * (V1 - V2) / Vsample

  10. Sulphuric acid determination • H2SO4 + Na2CO3 = Na2SO4 + H2O + CO2 • Mixed indicator • Use the solution remaining after the iron and copper titration or mask Fe3+ by addition of excess of KI and Na2S2O3 CH2SO4(mol/L) = CNa2CO3 * VNa2CO3 / Vsample

  11. Milled ore H2SO4 Leach oxidant 1 tails 2 3 S/L SX or IX 1- PLS (U, Fe2+, Fe3+, Cl- and acid titration) 2- feed (U and acid titration) 3- loaded strip liquor (U and acid titration) U ore processing

  12. Step 1: Pre-reduction of Uranium UO22+ + 2 Fe2+ + 4 H+ = U4+ + 2 Fe3+ + 2 H2O Strong phosphoric acid medium Step 2: Destruction of Fe(II)excess 4 Fe2+ + 2 HNO3 + 4 H+ = 4 Fe3+ + NO↑ + NO2↑ + 3 H2O Catalyst: ammonium molybdate U determination: redox titration

  13. Step 3: Destruction of NO or NO2 with sulphamic acid 2 (NH2)HSO3 + NO↑ + NO2↑= 2 H2SO4 + 2 N2↑+ H2O Step 4: Dilution with H2SO4 Step 5: Oxidation of U(IV) into U(VI) U4+ + 2VO2+ = UO22+ + 2V3+ or U4+ + 2 Fe3+ + 2 H2O = UO22+ + 2 Fe2+ + 4 H+ U determination: redox titration

  14. Step 6: Dichromatometric titration Cr2O72- + 6 V3+ + 2 H+ = 2 Cr3+ + 6 VO2+ + H2O or Cr2O72- + 6 Fe2+ + 14 H+ = 2 Cr3+ + 6 Fe3+ + 7 H2O Indicator: diphenylamine or Potentiometric titration C U(mol/L) = 3 * CK2Cr2O7* VK2Cr2O7 / Vsample U determination: redox titration

  15. Ag+ + Cl– = AgCl↓ Indicator: potassium chromate or dichromate 2 Ag+ + CrO42– = Ag2CrO4↓ Fe2+ pre-oxidation pH from 6.5 and 10 CCl(mol/L) = CAgNO3 * VAgNO3 / Vsample Cl determination: precipitation titration

  16. Thank you www.mintek.co.za

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