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Council for Mineral Technology
reliable results even in field conditions
Application of titration techniques for analysis
of hydrometallurgical solutions
By Volha Bazhko
Senior Scientist
Titration
Advantages of titration methods:
Do not require complicated and expensive
equipment
Simple and fast method
Reliable results even under plant conditions
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-
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
Cu/Co processing
Milled ore
H2SO4
SO2
Fe2+ /
Leach
Co bleed
product
Fe3+
1
tails
S/L
2
Cu SX
5
4
Cu EW
Cu0
1 PLS (Fe2+, Fe3+ and acid titration)
2 SX feed (Fe, Cu2+ and acid titration)
3 SX raffinate (Cu2+, Fe2+, Fe3+ and acid titration)
4 Advanced electrolyte (Cu2+ and acid titration)
5 Spent electrolyte (Cu2+ and acid titration)
3
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
SO2, Fe2+ and Fe3+ determination
Titration 3: Total iron determination
with EDTA.
Pre-oxidation of Fe2+ with H2O2
pH < 2
Indicator: sulphosalicylic acid
CFe III (mol/L) = CEDTA * V2 / Vsample
CFe II (mol/L) = CEDTA * (V3 - V2) / Vsample
CSO (mol/L) = 3(CK Cr O * VK Cr O –
- (CFeSO * V1 + CEDTA * (V3 - V2)) / 6 ) / Vsample
2
2
4
2
7
2
2
7
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
2 CuSO4 + 4 KI = 2 CuI↓ + 2 K2SO4 + I2
• Titration of I2 liberated
I2+ 2 Na2S2O3 = Na2S4O6 + 2 NaI
Indicator: starch.
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) = CNa S O * V2 / Vsample
2 2
3
CFe (mol/L) = CNa S O * (V1 - V2) / Vsample
2 2
3
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
CH SO (mol/L) = CNa CO * VNa CO / Vsample
2
4
2
3
2
3
U ore processing
Milled ore
H2SO4
oxidant
Leach
1
tails
S/L
2
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)
3
U determination: redox titration
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
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
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 * CK Cr O * VK Cr O / Vsample
2
2
7
2
2
7
Cl determination: precipitation titration
Ag+ + Cl– = AgCl↓
•Indicator: potassium chromate or dichromate
2 Ag+ + CrO42– = Ag2CrO4↓
•Fe2+ pre-oxidation
•pH from 6.5 and 10
CCl (mol/L) = CAgNO * VAgNO / Vsample
3
3
Thank you
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