christie dorfling
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Tellurium precipitation fromcopper sulfate leach solutionsYusuf Bello and Christie Dorfling
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Introduction
• Impurities such as Se, Te have to be removed
from Cu leach solution
–Reduced electrowinning efficiency
– Poor Cu cathode quality
• Sulfurous acid often used for impurity
precipitation
– Se removal as Cu2Se satisfactory
– Te removal remains challenging
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Background
• Te precipitation reactions
– 4Cu + H2TeO3 + 2H2SO4 → Cu2Te + 2CuSO4 + 3H2O
–5Cu + H6TeO6 + 3H2SO4 → Cu2Te + 3CuSO4 + 6H2O
• Copper formation reactions
– 2CuSO4
+ H2
SO3
+ H2
O → Cu2
SO4
+ 2H2
SO4
– Cu2SO4 → CuSO4 + Cu
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Aim and objectives
• Investigate the effects of Cu addition on Te
precipitation behavior at different operating
conditions
– Improved understanding of Te precipitation
– Conditions for Te removal with minimal Cu losses
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Experimental conditions
SO2 only SO2 + Cu powder SO2 + Cu plate
Cu addition N/A1 g/L
2 g/L
203 mm2/L,
405 mm2/L
Temperature65°C
95°C
65°C
95°C
65°C
95°C
SO2 flow rate4.4 mL/min
5.8 mL/min
4.4 mL/min
5.8 mL/min
4.4 mL/min
5.8 mL/min
Agitation rate250 rpm
500 rpm
250 rpm
500 rpm
250 rpm
500 rpm
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Experimental setup
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Agitation(65°C, 4.4 mL SO2/min)
0
20
40
60
80
100
0 100 200 300 400 500
SO2
250 rpm
500 rpm
%
T e p r e c i p i t a t e d
Time (minutes)
0
20
40
60
80
100
0 100 200 300 400 500
SO2 + Cu plate
250 rpm
500 rpm
Time (minutes)
%
T e p r e c i p i t a t e d
0
20
40
60
80
100
0 100 200 300 400 500
SO2 + Cu powder
250 rpm500 rpm
Time (minutes)
%
T e p r e c i p i t a t e d
% Te precipitation
SO2
SO2 + Cu
plates
SO2 + Cu
powder
65°C 95°C 65°C 95°C 65°C 95°C
250 rpm 80.0 93.0 87.8 91.8 91.5 94.0
500 rpm 73.0 95.5 77.3 92.5 92.0 94.0
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SO2 flow rate(65°C, 250 rpm)
0
20
40
60
80
100
0 100 200 300 400 500
SO2
4.35mL/min
5.80mL/min
Time (minutes)
%
T e p r e c i p i t a t e d
0
20
40
60
80
100
0 100 200 300 400 500
SO2 + Cu plate
4.35mL/min
5.80mL/min
Time (minutes)
%
T e p r e c i p i t a t e d
0
20
40
60
80
100
0 100 200 300 400 500
% T e p r e c
i p i t a t e d
Time (minutes)
SO2 + Cu powder
4.35mL/min5.80mL/min
% Te precipitation
SO2
SO2 + Cu
plates
SO2 + Cu
powder
65°C 95°C 65°C 95°C 65°C 95°C
4.4 mL/min 69.0 93.5 76.8 91.8 91.3 93.8
5.8 mL/min 84.0 95.0 88.3 92.5 92.3 94.3
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Temperature(250 rpm, 4.4 mL SO2/min)
0
20
40
60
80
100
0 100 200 300 400 500
SO2
65˚C
95˚C
%
T e p r e c i p i t a t e d
Time (minutes)
0
20
40
60
80
100
0 100 200 300 400 500
SO2 + Cu plate
65°C
95˚C
%
T e p r e c i p i t a t e d
Time (minutes)
0
20
40
60
80
100
0 100 200 300 400 500
%
T e p r e c i p i t a t e d
Time (minutes)
SO2 + Cu powder
65°C
95°C
% Te precipitation
SO2
SO2 + Cu
plates
SO2 + Cu
powder
65°C 76.5 82.5 91.8
95°C 94.3 92.1 94.0
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Solid characterization
SEM image of precipitate
obtained at 65°C
SEM image of precipitate
obtained at 95°C
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Cu addition(250 rpm, 4.4 mL SO2/min)
0
20
40
60
80
100
0 100 200 300 400 500
%
T e p r e c i p i t a t e d
Time (minutes)
65°C
SO₂ only
SO₂ & 202.5 mm² Cu plateSO₂ & 405.0 mm² Cu plate
SO₂ & 1g Cu powder
SO₂ & 2g Cu powder
0
20
40
60
80
100
0 100 200 300 400 500
% T e p r e c i p i t a t e d
Time (minutes)
95°C
SO₂ only
SO₂ & 202.5 mm² Cu plateSO₂ & 405.0 mm² Cu plate
SO₂ & 1g Cu powder
SO₂ & 2g Cu powder
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Concluding remarks
• Large Cu specific surface area
– Te precipitation not dependent on Cu2+ reduction
–Fast Te precipitation exceeding 90%
• Small Cu specific surface area
– Te precipitation dependent on Cu2+ reduction
– Cu2+ reduction rate highly dependent on
temperature