Peter Amelunxen

7/30/2019 Peter Amelunxen

1/20

The Use of Column Flotation in MolyPlants

Why it Works and Why it Doesnt

Peter Amelunxen

Director of Metallurgy, Aminpro Chile


2/20

Relevance

20%

25%

30%

35%

40%45%

Percent of World Mine Production (2009)Andacollo

Andina Phase 2

Caserones

Chuquicamata Subterraneo

Collahuasi Expansion

El Abra Sulfide

Some Chilean Greenfields orBrownfields Projects with

Moly Production Potential

0%

5%

10%

15%Esperanza & Sierra Gorda DistrictLomas Bayas

Los Bronces

Radimiro Tomic Sulfide

Relincho

Quebrada BlancaSierra Gorda (Quadra)Source: USGS Minerals Resource Program, 2009


3/20

Moly Flotation in Cu/Mo Columns12.1 %Cu

2.49 %Mo

23.1 %Cu

0.59 %Mo

7.5 %Cu

Conc.

18.8 %Cu

0.26 %Mo

from Rougher Conc

2nd Cleaners% Cu Rec = 56%

% Mo Rec = 7%

Ca = 1.7 t/hm2Cleaner Circuit (Overall)

% Cu Rec = 99.1%

% Mo Rec = 92.7%.

6.9 %Cu

0.75 %Mo7.4 %Cu

2.63 %Mo

from regrind

to regrind

Tails

9.5 %Cu

3.36 %Mo

1.9 %Cu

1.9 %Mo

0.338 %Cu

0.068 %Mo

1st Cleaners% Cu Rec = 98%

% Mo Rec = 97%


4/20

Mechanical Cells (1st Cleaner)

0

5

10

15

20

25

30

stCell

dC

ell

hC

ell

hC

ell

hC

ell

hC

ell

hC

ell

hC

ell

hC

ell

hC

ell

TPH Cu over Lip

1.5

2.0

2.5

3.0

TPH Mo over Lip

Carry Rate (TPH/m2)1

2n

3

4

5

6

7

8

9

10

0.0

0.5

.

1stCell

2ndC

ell

3thC

ell

4thC

ell

5thC

ell

6thC

ell

7thC

ell

8thC

ell

9thC

ell

10thC

ell

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

1stCell

2ndC

ell

3thC

ell

4thC

ell

5thC

ell

6thC

ell

7thC

ell

8thC

ell

9thC

ell

10thC

ell

Crowding of slower floating species in

the froth zone of column cell? If so,

this would not apply to Cu/Mo Sep!


5/20

Copper Moly Separation

Reference Point

Use of NaHS as depressant (no CN, no Nokes)

I will refer to a Typical moly circuit

Mechanical roughers, 1st cleaners

Co umn Ce s or 2n

-4 c eaners Counter-current cleaners

Cleaner-scavenger tails returned to the bulk thickener

Oxygen-depleted air or nitrogen in roughersAir-sparged columns


6/20

Redox Potential

Below -450 mV Ag/AgCl, copper sulfides are completelydepressed3

Predominant recovery mechanism is entrainment

Mineral Recovery in a Batch Test

70

80

90

100

(%)

Molybdenite Recovery

0

10

20

30

40

50

0 5 10 15 20 25 30 35

Time (minutes)

Recovery

Chalcopyrite and Gangue Recovery

Rcol = Rmax (1 e-kt)

R = RcolRf/ ( 1 Rcol + RcolRf)


7/20

pH

NaHS oxidation drives the pH up, depressingMoly

Rmax

90

100K

3.0MoS2 K MoS2 K

CuFeS2 K CuFeS2 K

2NaHS 2Na+ + 2HS-

2HS- + O2(aq) OH- + S2(s)Global: 2NaHS + O2(aq) OH

- + S2(s)

0

10

20

30

40

50

6070

7 8 9 10 11 12 13 14pH (eH=-536 mV; P80=24.3 m)

Rmax(%)

MoS2 Rmax MoS2 Rmax

CuFeS2 Rmax CuFeS2 Rmax

FeS2 Rmax FeS2 Rmax

Insol Rmax Insol Rmax

0.0

0.5

1.0

1.5

2.0

.

8 9 10 11 12 13pH (eH=-536 mV; P80=24.3 m)

K(1/min)

FeS2 K FeS2 K

Insol K Insol K


8/20

P80 Finer P80s depress Moly

1.5

2.0

2.5

n)

0.0

0.5

1.0

20 25 30 35 40 45 50 55 60

P80 (m)

K(1/mi

MoS2 RoughersMoS2 Cleaners

CuFeS2

FeS2

Insol

As

Pb


9/20

% Solids

Lower % solids improves kinetics

Shorter residence times at lower % solids

80

90

100

Effect of Flotation Pulp Density on Mo 2nd Cleaner Kinetics

0

10

20

30

40

50

60

70

0 5 10 15 20 25 30 35

MoRecovered,

%

Lab Flot Time, minutes

5.6% solids

11% solids

22% solids

32.7% solids


10/20

Simple Moly Circuit

FeedTail

Roughers

H2O H2O

Cleaner Columns

O2-depleted air or N2


NaHS

1st Cleaners

Air Air

NaHS


11/20

Moly Section Recovery

40

50

60

70

80

90

100

ectionRecov

ery


0

1020

Jul-98 Dec-99 Apr-01 Sep-02 Jan-04 May-05

Mo

Month

Monthly Shift Average

Real, Unfiltered, Historical Production Data North American Cu/Mo Porphyry Plant

2.5 kg/ t NaHS Nitrogen roughers, air-sparged columns No pH control in the cleaners


12/20

What Can Also Happen

FeedTail

Roughers

H2O H2O

Cleaner Columns



NaHS

Operators Increase NaHS to

Reduce froth, control

spillage

Tails % Mo goes up as

operators try to control

spillage

Maybe they also shut offthe wash water

Poor cleaner performance

drives the moly rougher

head grade up

so they add more NaHS

1st Cleaners

Air Air

NaHS

This pump is not sized

properly for froth pumping

Increased NaHS leads to

higher pH in the columns

Higher pH leads to lower

column stage recovery

Operators increase air rate

to try to improve column

recovery

The pump speed is already at

100%, and the floor is full of

concentrate, so the operatorscant pull any harder


13/20


14/20


-20

0

20

40

60

80

100


-100

-80

-60

-40

06-ago-07 25-sep-07 14-nov-07 03-ene-08 22-feb-08 12-abr-08 Real, Unfiltered, Historical Production Data South American Cu/Mo Porphyry Plant

15 kg/ t NaHS Nitrogen roughers, air-sparged columns No pH control in the cleaners


15/20

What is the Solution?

FeedTail

Roughers

H2O H2O

Cleaner Columns



NaHS

Passive pH control in the

cleaners, through nitrogen

sparging and NaHS

reduction

1st Cleaners

Air Air

NaHS

Active pH control in the

cleaners through CO2 or

H2SO4

Eliminate the column cells

and replace them withmechanical cells operating

on N2 or O2-depleted air


16/20

Effect of CO2

pH 10.0

pH 12.4


17/20

Benefits of Columns

MoS2 Upgrading Profile - Column Cells

40

50

60

70

80

90

100

Grade(%MoS2) 54

3

2

MoS2 Upgrading Profile - Mechanical Cells

40

50

60

70

80

90

100

Grade(%MoS2) 8

7

6

5

4

(when operated properly)

0

10

20

30

0 10 20 30 40 50 60 70 80 90 100

Feed Grade (%MoS2)

Co

nc

Columns

y = x

Column Stages1

0

1020

0 10 20 30 40 50 60 70 80 90 100

Feed Grade, %MoS2

Con

Mechanical

y = x

Mech Stages1

32


18/20

Benefits of Columns(when operated properly)

Mineral Rmax vs pH

70

80

90

100

eledRmax(%)

H2O

50

60

8.0 8.5 9.0 9.5 10.0 10.5 11.0 11.5 12.0 12.5 13.0

pH

M

od

Model Curve

MM2 Tests (Sea Water)

MM1 Tests (Tap Water)


19/20

Summary Columns can negatively impact moly recovery

when

There is potential for froth crowding by hydrophicnon-molybdenum particles (bulk Cu/Mo circuits)

The are s ar ed with air and the cleaner H is

uncontrolled (Cu/Mo separation circuits) In most other cases, columns will offer superior

cleaning performance because they

Eliminate entrainment of other metal sulfidesEliminate entrainment of any salts


20/20

Thank You

Documents

Peter Amelunxen