By Rafael Giner, University Assistant, Scientist-Technical University of Graz. This was presented during the New Ideas for the Paper Industry: Young Researchers' Presentations session, organised as part of European Paper Week 2015. More at http://www.cepi.org/epw

1. u www.tugraz.at
Fractionated treatment and
separate refining of pulp to reduce
energy consumption
17.11.2015
Rafael Giner Tovar
Institute of Pulp, Paper and Fibre Technology
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2. Outline
• Introduction
• Fractionation and separate refining
• Results
• Conclusions
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3. Introduction
Why refining?
• Refining
 Process engineering → milling process
 Pulp and paper industry → forming process
• Through refining, fibres are…
 internally fibrillated → higher flexibility
 externally fibrillated → fines production, higher bonding area
 long fibres are shortened
 ideally, short fibres are not affected
 better fibre-fibre bonding
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4. • Refining needed in stock preparation, improving
 fibre-fibre bonding ability
 sheet formation
 physical properties of the final product
• Unrefined pulp
 lower sheet strength
 rough surface
• Chemical and mechanical pulp need to be refined before they
become suitable for papermaking
Refining can represent up to 60% of the total power consumption
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Introduction
Why refining?

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Introduction
Thermomechanical Pulp (TMP) Plant

6. Outline
• Introduction
• Fractionation and separate refining
• Results
• Conclusions
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7. Fractionation and separate refining
• Fractionation is used to separate pulp into fine and coarse fraction
• Fine fraction
 can have higher tensile strength than the coarse fraction
 their properties do not improve through refining
• Coarse fraction
 only the coarse fraction needs to be refined
 refining only coarse fraction energy consumption could be
reduced
• Different types of fractionation devices available
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8. Fractionation and separate refining
Types of refiners
• Lab scale
 Jokro mill
 PFI Mill
 Valley Beater
• Industrial refiner (e.g)
 Voith Sulzer Twinflo E
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(PFI Mill, Frank-PTI)
(Valley Beater, Frank-PTI)
(Jokro Mill, Frank-PTI)

9. Fractionation and separate refining
Fractionation on the lab scale
Preparation of the sample
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Mesh
16
Mesh
30
Mesh
50
Mesh
200
Fines
Fine fraction
Coarse
fraction
Bauer McNett

10. 1. Refining of the entire sample (reference)
2. Refining of the coarse fraction
3. Refining of the fine fraction
• Refining performed using a Jokro Mill
 600 rpm in desintegrator
 20 minutes, 150 rpm
 240 rpm in desintegrator
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Fractionation and separate refining
Refining on the lab scale

11. • Preparation of handsheets (Rapid-Köthen)
• Determination of properties such as thickness/density, tensile
strength, beating degree (°SR), air permeability
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Coarse
Mesh (16)
Fine Mesh
(30,50,200)
Fines
(<200) BrittJar
Jokro-
mill
Mixture
representing
whole pulp
Sheet-
forming
Fractionation and separate refining
Sheet forming and mechanical testing
Refining of the coarse fraction

12. Outline
• Introduction
• Fractionation and separate refining
• Results
• Conclusions
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0
20
40
60
80
100
120
140
160
180
Thickness(µm)
Thickness
Unrefined
Entire sample
Coarse fraction refined
Fine fraction refined
0
1000
2000
3000
4000
5000
6000
7000
8000
9000
10000
Breakinglengh(m)
Breaking length
Unrefined
Entire sample
Coarse fraction refined
Fine fraction refined
0
2
4
6
8
10
12
14
16
18
°SR
Schopper-Riegler
Unrefined
Entire sample
Coarse fraction
Fine fraction
0
1000
2000
3000
4000
5000
6000
Airpermeability(ml/min)
Air permeability
Unrefined
Entire sample
Coarse fraction refined
Fine fraction

14. Outline
• Introduction
• Fractionation and separate refining
• Results
• Conclusions
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15. Conclusions
• Refining improves the paper properties
• Promising results when the coarse fraction is refined compared to
refining the whole sample
 Similar effect on dewatering
 Comparable results on thickness
 Comparable results on air permeability
 40% less material refined → similar increase in breaking length → energy
savings
• Future trials using different pulps and coarse/fine fraction ratios
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