Transcript Presentation to [TITLE OF PRESENTATION]

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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