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
3DB– September, 2007
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
4DB– September, 2007
Guideline
Motivations and objectivesMaterials and methods
• Laboratory flotation test procedure• Data analysis and process simulation
Results• Laboratory flotation tests• Process simulation
Conclusions
5DB– September, 2007
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
6DB– September, 2007
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
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
7DB– September, 2007
Materials and methodsLaboratory flotation test procedure
Air
Pulp chest
Floated pulp
Froth collection
To vacuum pump
Adjustable froth removal
Pulp aeration line
High consistencypulping
• Furnish:50% OMG/50%ONP
• Consistency: 13%
• Temperature: 45°C
• Pulping time: 15 min
• Ca2+: 150 mg/L
Laboratory continuous flotation• Consistency: 0.8% • Temperature: ~40°C• Ca2+: 150 mg/L
8DB– September, 2007
Materials and methodsLaboratory flotation test procedure
Air
Pulp chest
Floated pulp
Froth collection
To vacuum pump
Adjustable froth removal
Pulp aeration line
High consistencypulping
• Furnish:50% OMG/50%ONP
• Consistency: 13%
• Temperature: 45°C
• Pulping time: 15 min
• Ca2+: 150 mg/L
Laboratory continuous flotation• Consistency: 0.8% • Temperature: ~40°C• Ca2+: 150 mg/L
• Pulp feed flow: 2 L/min
9DB– September, 2007
Materials and methodsLaboratory flotation test procedure
Air
Pulp chest
Floated pulp
Froth collection
To vacuum pump
Adjustable froth removal
Pulp aeration line
High consistencypulping
• Furnish:50% OMG/50%ONP
• Consistency: 13%
• Temperature: 45°C
• Pulping time: 15 min
• Ca2+: 150 mg/L
Laboratory continuous flotation• Consistency: 0.8% • Temperature: ~40°C• Ca2+: 150 mg/L
• Pulp feed flow: 2 L/min • Air flow: 4 L/min
10DB– September, 2007
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
Laboratory continuous flotation• Consistency: 0.8% • Temperature: ~40°C• 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
Adjustable froth removal
Pulp aeration line
11DB– September, 2007
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
Laboratory continuous flotation• Consistency: 0.8% • Temperature: ~40°C• 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
Adjustable froth removal
Pulp aeration line
12DB– September, 2007
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
Laboratory continuous flotationPulp characterization• ERIC, Brightness• Ash content (475°C), fibre content• Mass flow
Air
Pulp chest
Floated pulp
Froth collection
To vacuum pump
Adjustable froth removal
Pulp aeration line
13DB– September, 2007
Motivations and objectivesMaterials and methods
• Laboratory flotation test procedure• Data analysis and process simulation
Results• Laboratory flotation tests • Process simulation
Conclusions
Guideline
14DB– September, 2007
Materials and methodsData analysis and process simulation
Flotation de-inking modelling
ngnn c
SQK
dtdc α
−=
SQK
k gnn
α⋅=
Air
Pulp chest
d
Adjustable froth removal
Pulp aeration line
S cell cross sectionQg air flowcn particle concentrationKn experimental flotation rate
Flotation
15DB– September, 2007
Materials and methodsData analysis and process simulation
nfn c
VQ
dtdc 0⋅
−=φ
Air
Pulp chest
d
Adjustable froth removal
Pulp aeration line
V cell volumeQf
0 water upstream flowcn particle concentrationφ entrainment coefficient
Flotation de-inking modelling
Entrainment
16DB– September, 2007
Materials and methodsData analysis and process simulation
gf
f
QQQ+
=ε
FRTLde ⋅−⋅= 0εεAir
Pulp chest
d
Adjustable froth removal
Pulp aeration line
Flotation de-inking modelling
Frothing
ε water holdupε0 water holdup at the froth/pulp interfaceQf water upstream flowQg gas flowFRT froth retention timeLd water drainage coefficient
17DB– September, 2007
Materials and methodsData analysis and process simulation
dnff Qc
dtdM
⋅⋅−= δ
Air
Pulp chest
d
Adjustable froth removal
Pulp aeration line
Flotation de-inking modelling
Drainage
dMf /dt particle drainage rateδ particle drainage coefficientcnf particle concentration in the frothQd water drainage flow
18DB– September, 2007
Materials and methodsData analysis and process simulation
Air
Pulp chest
d
Adjustable froth removal
Pulp aeration line
Flotation de-inking modelling
Laboratoryflotation tests
Experimentaldata fitting with
model equations
Extraction of transport
coefficients
Process scale-up and design usingmodel equations
Industrial line simulation
19DB– September, 2007
Materials and methodsData analysis and process 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
20DB– September, 2007
Materials and methodsData analysis and process simulation
Industrial pre-flotation line
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
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
21DB– September, 2007
Guideline
Motivations and objectivesMaterials and methods
• Laboratory flotation test procedure• Data analysis and process simulation
Results• Laboratory flotation tests• Process simulation
Conclusions
22DB– September, 2007
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
23DB– September, 2007
)
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
Comparison of fatty acid soap and fatty acid-surfactant blend
Fines consistency in the frothAsh consistency in the froth
ResultsLaboratory flotation tests
24DB– September, 2007
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
Comparison of fatty acid soap and fatty acid-surfactant blend
Water loss vs. froth removal thickness Water holdup in the froth vs. FRT
ResultsLaboratory flotation tests
25DB– September, 2007
Flotation yield of tested deinking chemicals
a)
0
5
10
15
20
25
0 1 2 3 4 5 6
Froth thickness (cm)
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
Froth thickness (cm)
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
Froth thickness (cm)
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
Froth thickness (cm)
Tota
l los
s (%
)
Soap, 2% Silicate
Soap, 1% silicate
Blend, 2% silicate
Blend, 1% silicate
26DB– September, 2007
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
ResultsLaboratory flotation tests
27DB– September, 2007
Guideline
Motivations and objectivesMaterials and methods
• Laboratory flotation test procedure• Data analysis and process simulation
Results• Laboratory flotation tests• Process simulation
Conclusions
28DB– September, 2007
Process yield
ResultsProcess simulation
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
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
29DB– September, 2007
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 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
Air
Pulp chest
d
Adjustable froth removal
Pulp aeration line
Lab flotation column
Industrial pre-flotation line
30DB– September, 2007
Guideline
Motivations and objectivesMaterials and methods
• Laboratory flotation test procedure• Data analysis and process simulation
Results• Laboratory flotation tests• Process simulation
Conclusions
31DB– September, 2007
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
Adjustable froth removal
Pulp aeration line
32DB– September, 2007
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 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