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Deinking chemistry performance: from laboratory flotation tests to the

simulation of an industrial pre-flotation lineD. Beneventi, B. Carré, T. Hannuksela and S. Rosencrance

Air Air Air Air Air Air

Air Air

Froth 1ry stage

Froth 2ry stage

Cell 1

Cell 2

Cell 3

Cell 4

Cell 5

Cell 6

Cell 1

Cell 2

Floated pulp

Pulp feed

2ry stage

1ry stage

2DB– September, 2007

Guideline

Motivations and objectivesMaterials and methods

• Laboratory flotation test procedure• Data analysis and process simulation

Results• Laboratory flotation tests• Process simulation

Conclusions


Extrapolation of laboratory flotation tests to the industrial scale difficult/misleading

Absence of a laboratory test/data analysis procedure to interpret and simulate the action of deinking chemicals at lab and industrial scale

Motivations and objectives

To develop a lab test procedure and a simulation tool to predict the influence of process chemistry on deinking selectivity in industrial lines

Lab benchmark test

Data analysis and process simulation

Selectivity in industrial lines


Guideline




Conclusions


Materials and methodsLaboratory flotation test procedure

High consistencypulping

• Furnish:50% OMG/50%ONP

• Consistency: 13%

• Temperature: 45°C

• Pulping time: 15 min

• Ca2+: 150 mg/L








• Ca2+: 150 mg/L

Re-pulping chemistry NaOH (%) Silicate (%) Peroxide (%) Collector (%) Soap, 2% silicate 0.7 2 0.7 0.45 Soap, 1% silicate 0.7 1 0.7 0.45 Blend, 2% silicate 0.7 2 0.7 0.15 Blend, 1% silicate 0.7 1 0.7 0.15

Re-pulping chemistries tested in this study Re-pulping chemistry NaOH (%) Silicate (%) Peroxide (%) Collector (%) Soap, 2% silicate 0.7 2 0.7 0.45 Soap, 1% silicate 0.7 1 0.7 0.45 Blend, 2% silicate 0.7 2 0.7 0.15 Blend, 1% silicate 0.7 1 0.7 0.15

Re-pulping chemistries tested in this study



Air

Pulp chest

Floated pulp

Froth collection

To vacuum pump

Adjustable froth removal

Pulp aeration line






• Ca2+: 150 mg/L

Laboratory continuous flotation• Consistency: 0.8% • Temperature: ~40°C• Ca2+: 150 mg/L



Air

Pulp chest

Floated pulp

Froth collection

To vacuum pump


Pulp aeration line






• Ca2+: 150 mg/L


• Pulp feed flow: 2 L/min



Air

Pulp chest

Floated pulp

Froth collection

To vacuum pump


Pulp aeration line






• Ca2+: 150 mg/L


• Pulp feed flow: 2 L/min • Air flow: 4 L/min








• Ca2+: 150 mg/L


• Pulp feed flow: 2 L/min • Air flow: 4 L/min• Cell volume: 14.5 L

Air

Pulp chest

Floated pulp

Froth collection

To vacuum pump


Pulp aeration line








• Ca2+: 150 mg/L


• Pulp feed flow: 2 L/min

• Froth removal thickness: 1, 2, 3, 5 cm

• Air flow: 4 L/min• Cell volume: 14.5 L

Air

Pulp chest

Floated pulp

Froth collection

To vacuum pump


Pulp aeration line








• Ca2+: 150 mg/L

Laboratory continuous flotationPulp characterization• ERIC, Brightness• Ash content (475°C), fibre content• Mass flow

Air

Pulp chest

Floated pulp

Froth collection

To vacuum pump


Pulp aeration line




Results• Laboratory flotation tests • Process simulation

Conclusions

Guideline


Materials and methodsData analysis and process simulation

Flotation de-inking modelling

ngnn c

SQK

dtdc α

−=

SQK

k gnn

α⋅=

Air

Pulp chest

d


Pulp aeration line

S cell cross sectionQg air flowcn particle concentrationKn experimental flotation rate

Flotation



nfn c

VQ

dtdc 0⋅

−=φ

Air

Pulp chest

d


Pulp aeration line

V cell volumeQf

0 water upstream flowcn particle concentrationφ entrainment coefficient


Entrainment



gf

f

QQQ+

=ε

FRTLde ⋅−⋅= 0εεAir

Pulp chest

d


Pulp aeration line


Frothing

ε water holdupε0 water holdup at the froth/pulp interfaceQf water upstream flowQg gas flowFRT froth retention timeLd water drainage coefficient



dnff Qc

dtdM

⋅⋅−= δ

Air

Pulp chest

d


Pulp aeration line


Drainage

dMf /dt particle drainage rateδ particle drainage coefficientcnf particle concentration in the frothQd water drainage flow



Air

Pulp chest

d


Pulp aeration line


Laboratoryflotation tests

Experimentaldata fitting with

model equations

Extraction of transport

coefficients

Process scale-up and design usingmodel equations

Industrial line simulation



Industrial pre-flotation line

Cell volume (L)

Cell cross section area (m2)

Pre-flotation feed flow (L/min)

Cell nominal flow (L/min)

Gas flow (L/min)

Number of 1ry cells

Number of 2ry cells

Recirculation rate on 2ry cells (%)

24000 12 30000 40000 20000 6 2 71

Parameters used to simulate an industrial pre-flotation unit





Air Air

Froth 1ry stage

Froth 2ry stage

Cell 1

Cell 2

Cell 3

Cell 4

Cell 5

Cell 6

Cell 1

Cell 2

Floated pulp

Pulp feed

2ry stage

1ry stage

Cell volume (L)

Cell cross section area (m2)

Pre-flotation feed flow (L/min)

Cell nominal flow (L/min)

Gas flow (L/min)

Number of 1ry cells

Number of 2ry cells

Recirculation rate on 2ry cells (%)

24000 12 30000 40000 20000 6 2 71

Parameters used to simulate an industrial pre-flotation unit


Guideline




Conclusions


Comparison of fatty acid soap and fatty acid-surfactant blend

100

200

300

400

500

600

700

800

900

1000

0 10 20 30 40 50

Time (min)

ERIC

(ppm

)

Soap, 1% silicate

Blend, 1% silicate

2 cm 1cm 3 cm 5 cm

b)

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

0 10 20 30 40 50Time (min)

Fibr

e co

nsis

tenc

y (g

/L)

Soap, 1% silicate

Blend, 1% silicate

2 cm 1cm 3 cm 5 cm

ERIC of floated pulp Fibre consistency in the froth

ResultsLaboratory flotation tests


)

0

1

2

3

4

5

6

7

8

9

0 10 20 30 40 50Time (min)

Ash

con

sist

ency

(g/L

)

Soap, 1% silicate

Blend, 1% silicate

2 cm 1cm 3 cm 5 cm

b)

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

5.5

6.0

0 10 20 30 40 50

Time (min)

Fine

s co

nsis

tenc

y (g

/L)

Soap, 1% silicate

Blend, 1% silicate

2 cm 1cm 3 cm 5 cm


Fines consistency in the frothAsh consistency in the froth



0

5

10

15

20

25

30

35

0 1 2 3 4 5 6

Froth thickness (cm)

Wat

er lo

ss (%

)

Soap, 2% silicate

Soap, 1% silicate

Blend, 2% silicate

Blend, 1% silicate

b)

0

0.02

0.04

0.06

0.08

0.1

0.12

0.14

0.16

0 2 4 6 8 10 12 14 16 18

Retention time (s)

Wat

er h

oldu

p (%

)

Soap, 2% silicate

Soap, 1% silicate

Blend, 2% silicate

Blend, 1% silicate


Water loss vs. froth removal thickness Water holdup in the froth vs. FRT



Flotation yield of tested deinking chemicals

a)

0

5

10

15

20

25

0 1 2 3 4 5 6


Fibr

e lo

ss (%

)

Soap, 2% silicate

Soap, 1% silicate

Blend, 2% silicate

Blend, 1% silicate

b)

0

5

10

15

20

25

30

35

40

0 1 2 3 4 5 6


Fine

s lo

ss (%

)

Soap, 2% silicate

Soap, 1% silicate

Blend, 2% silicate

Blend, 1% silicate

c)

0

10

20

30

40

50

60

70

0 1 2 3 4 5 6


Ash

loss

(%)

Soap, 2% silicate

Soap, 1% silicate

Blend, 2% silicate

Blend, 1% silicate

d)

0

5

10

15

20

25

30

35

40

0 1 2 3 4 5 6


Tota

l los

s (%

)

Soap, 2% Silicate

Soap, 1% silicate

Blend, 2% silicate

Blend, 1% silicate


Ink removal efficiency

62

64

66

68

70

72

74

76

78

0 1 2 3 4 5 6Froth thickness (cm)

Ink

rem

oval

(%)

Soap, 2% silicate

Soap, 1% silicate

Blend, 2% silicate

Blend, 1% silicate



Guideline




Conclusions


Process yield

ResultsProcess simulation


Air Air

Froth 1ry stage

Froth 2ry stage

Cell 1

Cell 2

Cell 3

Cell 4

Cell 5

Cell 6

Cell 1

Cell 2

Floated pulp

Pulp feed

2ry stage

1ry stage

36.4

44.3

33.8

41.4

7.8

13.1

7.6

12.2

2.64.2

1.1

15.2

35.6

20.3

36.3

5.9 5.85.5 5.46.6

3.23.1

7.52.9

0

5

10

15

20

25

30

35

40

45

50

Soap, 2% silicate Soap, 1% silicate Blend, 2% silicate Blend, 1% silicate

Loss

(%)

Total loss 1ry

Total loss 2ry

Fibre loss

Ash loss

Fines loss

Water loss


Laboratory and pre-flotation line flotationselectivity

ResultsProcess simulation

60

63

66

69

72

75

78

81

84

87

5 10 15 20 25 30 35

Total loss (%)

Ink

rem

oval

(%)

Soap, 2% silicate

Soap, 1% silicate

Blend, 2% silicate

Blend, 1% silicateSoap, 2% silicate

Soap, 1% silicate

Blend, 1% silicate

Blend, 2% silicate


Air Air

Froth 1ry stage

Froth 2ry stage

Cell 1

Cell 2

Cell 3

Cell 4

Cell 5

Cell 6

Cell 1

Cell 2

Floated pulp

Pulp feed

2ry stage

1ry stage

Air

Pulp chest

d


Pulp aeration line

Lab flotation column



Guideline




Conclusions


ConclusionsLaboratory flotation tests

Silicate decreases fibre loss by depressing fibre entrainment and promoting fibre drainage in the froth

A decrease in ink removal due to more intense ink drainage in the froth was also observed when increasing silicate dosage from 1 to 2%.

The fatty acid-surfactant blend gave a higher ink removal selectivity than that obtained with fatty acid soap

Air

Pulp chest

Floated pulp

Froth collection

To vacuum pump


Pulp aeration line


ConclusionsProcess simulation

The performance scale determined during laboratory trials was respected and further emphasized by the layout of the simulated line

The presence of a secondary stage in modern deinking lines boosts the ink removal selectivity

The fatty acid-surfactant blend used with 2% silicate demonstrated the most favourable deinkingperformance


Air Air

Froth 1ry stage

Froth 2ry stage

Cell 1

Cell 2

Cell 3

Cell 4

Cell 5

Cell 6

Cell 1

Cell 2

Floated pulp

Pulp feed

2ry stage

1ry stage

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