Fine particles separation in recovered paper suspensions · sedimentation evaluation l u m i n o u...
Transcript of Fine particles separation in recovered paper suspensions · sedimentation evaluation l u m i n o u...
Abb. 1
8th Research Forum on RecyclingNiagara Falls, ON Canada, 9/2007
Fine particles separation inrecovered paper suspensions
Wagner, J.; Putz, H.-J.; Schabel, S.*
* Technische Universität DarmstadtChair for Paper Science and Mechanical Process Engineering (PMV)
Abb. 2
Introduction:Why separating organic from anorganic fines?
How to quantify progress:Why lack of measurement techniques is a major problem
Our approach for measurement:- particle size distribution- settling velocity- image analysis
Separation results
Overview
Abb. 3
recovered paper56%
chemical pulp20%
mechanical pulp7%
fillers and coating pigments
13%
chemical additives4%
Raw materials for paper production
Raw material consumption in 2005 in Germany:25.5 million tons for 21.7 million tons paper production
Abb. 4
Recovered paper suspensions to be considered
• Packaging paper- Pulp - Filtrate from thickeners- Filtrate from paper machine wire
• Graphic paper- Flotation foam and sludge
• Tissue paper- Washer filtrate
Abb. 5
Inorganic and organic components in a flotation foam of a stock preparation for graphic recycling paper
Abb. 6
• Inorganic fines from fillers and coating pigments cause lowerstrength properties
• Effect of organic fines depends on surface condition:
degree of fibrillation strength properties
• Flotation and washingseparate both components from longer fibre material
low selectivity, losses during paper production
Fines in recovered paper suspensions
binding area inorganic components
fibre
Abb. 7
How to quantify progress
• Sedimentation-Balance
• Sedi-Graph (X-Ray)
• Manometer-Centrifuge
• Laser-Diffraction
• FiberLab
h
Abb. 8
Observing sedimentation of virgincomponents
250 ml
120 ml
38 ml
Cylinder height in ml
chemical pulp fines chemical pulp fines+
calcium carbonate
calcium carbonate
w3
Slide 8
w3 Sedimentationsgeschwindigkeiten ausrechnen und dazuschreibenwimi, 11/18/2006
Abb. 9
Sedimentation balance
coated paper fines
80 % inorganic
uncoated paper fines
50 % inorganic
mechanical pulp fines
0 % inorganic
Abb. 10
Particle size distributionsmeasured with laser diffraction
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
5
0.1 1 10 100 1000 10000
äquivalenter Kugeldurchmesser in micrometer
Volu
men
in %
gestrichenes Papiergestrichenes Papier + SchliffSchliffTMPCaCO3
Size of equivalent sphere in µm
Rel
. fre
quen
cy in
%
Equivalent particle diameter in µm
GWCoated paper + GWCoated paper
Abb. 11
Measuring sedimentation of componentswith a sedimentation balance
0
0,1
0,2
0,3
0,4
0,5
0,6
0,7
0,8
0,9
1
0,001 0,01 0,1 1 10
Sedimentation velocity in mm/s
Mas
s di
strib
utio
n su
m
CaCO3 + Fines I
CaCO3 + Fines II
CaCO3 + Fines III
CaCO3
Chem. Pulp Fines
Difference should beUtilizable forseparation
Abb. 12
Uncoated paper fines’ settling velocities
Sinkgeschwindigkeit, Papier ungestrichen, normiert auf g
0,00,10,20,30,40,50,60,70,80,91,0
1,00E-07 1,00E-06 1,00E-05 1,00E-04 1,00E-03 1,00E-02Sinkgeschwindigkeit [m/s]
Q3
0,5 Ma% 50g1 Ma% 50 g2 Ma% 50 g3 Ma% 50 gSediwaage 3,7 Ma%
Normalised on acceleration due to gravity g
Mas
s di
strib
utio
nsu
m
Sedimentation velocity in m/s
sedimentation balance at 3.7 % consistency
manometer centrifuge at x % consistency
Abb. 13
Coated paper fines’ settling velocities
0,0
0,1
0,2
0,3
0,4
0,5
0,6
0,7
0,8
0,9
1,0
1,00E-07 1,00E-06 1,00E-05 1,00E-04 1,00E-03 1,00E-02Sinkgeschwindigkeit [m/s]
Q3 1 Ma% 50 g
2 Ma% 50 g
3 Ma% 50 g
Sediwaage 3,7 Ma%
Sedimentation velocity in m/s
Mas
s di
strib
utio
n su
m
sedimentation balance at 3.7 % consistency
manometer centrifuge at x % consistency
Abb. 14
Comparison of Sed. Balance and Sedigraph
0102030405060708090
100
0.1 1.0 10.0 100.0
Equivalent spheric diameter in µm
Mas
s di
strib
utio
n su
m in
% SedimentationbalanceSedigraph
Abb. 15
Image analysis forsedimentation evaluation
lumino
usso
urce
cameraPCO 4000
observation window:• width: 30 mm• height: 20 mm
sedimentation cell
single picture → particle size
series of pictures → sedimentation velocity
technical data camera:•resolution: 4008 x 2672•frame rate: 5 frames/s•illumination time: 5 µs –
5 days
Abb. 16
Sequence
Abb. 17
Sedimentation test rig
Abb. 18
Separation results
0
10
20
30
40
50
60
model suspension sediment overflow
ash
cont
ent i
n %
model suspension (fitrate coatedpaper + filtrate groundwood)
-10,6 %
+ 20,1 %
36,4
%
25,8
%
56,5
%
Abb. 19
Latest Results with MechnicalTreatment
0
10
20
30
40
50
60
70
80
90
startsuspension sediment
ash
cont
ent i
n %
filtrate flotation sludge untreated filtrate flotation sludge treated with ultrasonic
81,3 %
74,8
%
70,5
%
Abb. 20
Latest Results: Visual Impression
Abb. 21
Conclusions
• Sedimentation of fines in pulp suspensions iscomplex and measurement difficult
• Combinations of measurement methods arenecessary for evaluating all relevant effects
• Most promising: combination of sedimentaion camera(organic particles) with sedimentation device (all particles)
• Still open questions and unsolved problemsremaining – disintegration and stabilisation seems to be essential