Fine particles separation in recovered paper suspensions Wagner, - - PowerPoint PPT Presentation

• Abb. 1

8th Research Forum on Recycling Niagara Falls, ON Canada, 9/2007

Fine particles separation in recovered paper suspensions

Wagner, J.; Putz, H.-J.; Schabel, S.*

* Technische Universität Darmstadt Chair 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 paper 56% chemical pulp 20% mechanical pulp 7% fillers and coating pigments 13% chemical additives 4%

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

• f a stock preparation for graphic recycling paper

• Abb. 6
• Inorganic fines from fillers and coating pigments cause lower

strength properties

• Effect of organic fines depends on surface condition:

degree of fibrillation strength properties

• Flotation and washing

separate 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 virgin components

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 dazuschreiben

wimi, 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 distributions measured with laser diffraction

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 Volumen in % gestrichenes Papier gestrichenes Papier + Schliff Schliff TMP CaCO3

Size of equivalent sphere in µm

• Rel. frequency in %

Equivalent particle diameter in µm

GW Coated paper + GW Coated paper

• Abb. 11

Measuring sedimentation of components with a sedimentation balance

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 Mass distribution sum CaCO3 + Fines I CaCO3 + Fines II CaCO3 + Fines III CaCO3

• Chem. Pulp Fines

Difference should be Utilizable for separation

• Abb. 12

Uncoated paper fines’ settling velocities

Sinkgeschwindigkeit, Papier ungestrichen, normiert auf g 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-02 Sinkgeschwindigkeit [m/s] Q3

0,5 Ma% 50g 1 Ma% 50 g 2 Ma% 50 g 3 Ma% 50 g Sediwaage 3,7 Ma%

Normalised on acceleration due to gravity g

Mass distribution sum

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-02 Sinkgeschwindigkeit [m/s] Q3 1 Ma% 50 g 2 Ma% 50 g 3 Ma% 50 g Sediwaage 3,7 Ma%

Sedimentation velocity in m/s Mass distribution sum

sedimentation balance at 3.7 % consistency manometer centrifuge at x % consistency

• Abb. 14

Comparison of Sed. Balance and Sedigraph

10 20 30 40 50 60 70 80 90 100 0.1 1.0 10.0 100.0 Equivalent spheric diameter in µm Mass distribution sum in % Sedimentation balance Sedigraph

• Abb. 15

Image analysis for sedimentation evaluation

luminous source camera PCO 4000

• bservation 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

10 20 30 40 50 60 model suspension sediment

• verflow

ash content in %

model suspension (fitrate coated paper + filtrate groundwood)

• 10,6 %

+ 20,1 %

36,4% 25,8% 56,5%

• Abb. 19

Latest Results with Mechnical Treatment

10 20 30 40 50 60 70 80 90 startsuspension sediment ash content in % 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 is

complex and measurement difficult

• Combinations of measurement methods are

necessary for evaluating all relevant effects

• Most promising: combination of sedimentaion camera

(organic particles) with sedimentation device (all particles)

• Still open questions and unsolved problems

remaining – disintegration and stabilisation seems to be essential