Christie Dorfling

7/23/2019 Christie Dorfling

http://slidepdf.com/reader/full/christie-dorfling 1/13

Tellurium precipitation fromcopper sulfate leach solutionsYusuf Bello and Christie Dorfling



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



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



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



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



Experimental setup



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)

%


0

20

40

60

80

100

0 100 200 300 400 500

SO2 + Cu powder

250 rpm500 rpm

Time (minutes)

%


% 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



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)

%


0

20

40

60

80

100

0 100 200 300 400 500

SO2 + Cu plate

4.35mL/min

5.80mL/min

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

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



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

%


Time (minutes)

0

20

40

60

80

100

0 100 200 300 400 500

SO2 + Cu plate

65°C

95˚C

%


Time (minutes)

0

20

40

60

80

100

0 100 200 300 400 500

%


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



Solid characterization

SEM image of precipitate

obtained at 65°C

SEM image of precipitate

obtained at 95°C



Cu addition(250 rpm, 4.4 mL SO2/min)

0

20

40

60

80

100

0 100 200 300 400 500

%


Time (minutes)

65°C

SO₂ only

SO₂ & 202.5 mm² Cu plateSO₂ & 405.0 mm² Cu plate

SO₂ & 1g 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





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



THANK YOU

Christie Dorfling

Documents

Transcript of Christie Dorfling