department of earth resources engineering, faculty of

Conclusions

Department of Earth Resources Engineering, Faculty of Engineering,

Kyushu University, Japan

Email address: [email protected]

Towards SDGs: the improvement of copper processing

using flotation for safe and sustainable copper productionGde Pandhe Wisnu Suyantara, Tsuyoshi Hirajima, Hajime Miki, Keiko Sasaki

Flotation is a water intensive process:

• Stringent regulation on using freshwater and freshwater restriction.

• CO2 emission from desalination plant for producing freshwater

from seawater in the desert area.

Flotation is chemical based separation

• Usage of hazardous chemical reagent for separation.

Natural contamination from hazardous minerals

• Processing of low grade copper ore usually contains

arsenic-bearing copper minerals, which might create

environmental, health, and economic problem.

Introduction

Copper Processing

Flotation challenges

Sodium Hydrosulfide (NaHS)

Copper depressant.

Harmful to the environment

Producing H2S, a toxic gas.

Results and Discussion

100

80

60

40

20

0

Recove

ry, %

111098.3pH

(A) 0 ppm kerosene Chalcopyrite Molybdenite

100

80

60

40

20

0

Rec

ove

ry, %

111098.3pH

(B) 104 ppm kerosene Chalcopyrite Molybdenite

Flotation of Cu-Mo in Seawater

Addition of kerosene

emulsion

Chalcopyrite (CuFeS2)

Molybdenite (MoS2)

in seawater

pH adjustment

Flotation experiments

100

80

60

40

20

0

Recove

ry, %

5004003002001000

Concentration of emulsified kerosene, mg/L

Molybdenite Chalcopyrite

Flotation of single minerals

without kerosene


with kerosene

Flotation of mixed minerals

with kerosene at pH 10

Surface images of chalcopyrite and molybdenite using

atomic force microscopy (AFM)

H2O2 for NaHS alternative


with H2O2 and 0 mM FeSO4

100

80

60

40

20

0

Recove

ry, %

0 0.1 1 10

H2O2 concentration, mM


(A) without FeSO4

Untreated

100

80

60

40

20

0

Recove

ry, %

0 0.1 1 10

H2O2 concentration, mM


(C) with 0.1 mM FeSO4

Untreated

CA: Contact angle

High CA value: hydrophobic

Low CA value: hydrophilic

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80

60

40

20

0

Cu r

ecove

ry, %

50403020100

Flotation time (min)

NaHS methodTreatment time (H2O2-Fe method):

5 min 60 min

100

80

60

40

20

0

Mo r

ecove

ry, %

50403020100

Flotation time (min)

NaHS methodTreatment time (H2O2-Fe method):

5 min 60 min

Copper

Molybdenum


with H2O2 and 0.1 mM FeSO4

Flotation of Cu-Mo

concentrate

Flotation: Separation process based

on the difference in surface

hydrophobicity of the minerals.

Air is used as separating agent.

• Hydrophobic minerals: water-

fearing love air bubble

• Hydrophilic minerals: water-

lovingwater

1. Mg(OH)2 and CaCO3

precipitates formed at pH

10 and 11 in seawater

can be used for

separating Cu-Mo using

kerosene

2. Oxidation treatment using

H2O2 and FeSO4 selective

oxidized chalcopyrite

separation of Cu-Mo is

possible.

Why? Proposed mechanism

1. Copper is essential for the development of clean energy. Flotation

can contribute to the clean production of copper by minimizing the

contaminant at the early stages of copper processing.

2. Seawater produces hydrophilic precipitates that can act as natural

copper depressants in the separation of Cu-Mo using flotation.

3. Seawater can be used to replace freshwater in Cu-Mo flotation

saving freshwater and reducing CO2 emission from the

desalination plant for mining operations in the desert area.

4. Oxidation treatment H2O2 with and without FeSO4 can be an

alternative for NaHS treatment as a copper depressant

reducing the exposure of harmful chemicals and protecting

the environment and the health of the employee.

Addition of H2O2 and

FeSO4

Chalcopyrite (CuFeS2)

Molybdenite (MoS2)

pH adjustment

Flotation experiments

Chalcopyrite

Molybdenite

Chalcopyrite

Molybdenite

Kerosene

addition at

pH 10

Kerosene adsorbed on molybdenite

preventing the adsorption of hydrophilic

Mg(OH)2 and CaCO3

Mg(OH)2 and

CaCO3 precipitate

Hydrophilic

surface

Hydrophobic

surface

Kerosene layer

Chalcopyrite

Molybdenite

Chalcopyrite

Molybdenite

H2O2

and

FeSO4

treatment

Chalcopyrite surface is covered by

various hydrophilic species. MoO2 and

MoO3 on the molybdenite surface is

easily dissolved into the solution.

Hydrophilic

surface

Hydrophobic

surface

MoO3 and MoO2

FeOOH and

Fe2(SO4)3

CuO and

Cu(OH)2

SO42-

S/S8

Flotation of Cu-Mo in Seawater H2O2 for NaHS alternative

Acknowledgement

department of earth resources engineering, faculty of

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