IUFRO All-Division-5 Conference “Forest Products and Environment – A Productive Symbiosis”

1Götz Martin, Institute of Forest Utilization and Work Science

Albert-Ludwigs-Universität Freiburg, Germany

IUFRO All-Division-5 Conference“Forest Products and Environment – A Productive

Symbiosis”October 29 – November 2, 2007

Taipei, Taiwan

Wood and Fibre properties of Norway spruce (Picea abies) and Scots pine (Pinus

sylvestris) and their impact on the quality of stone groundwood pulp

Götz Martin, Gero Becker, Heiner Grussenmeyer,

Leif Nutto, Peter Neukum



Introduction (1)

• difficult situation for the European pulp and paper industry

– increasing costs for energy and raw materials

– overcapacities on the paper market

– old machinery– very competitive pulp and

paper mills in South America and China

Preisentwicklung Papierindustrie

0

20

40

60

80

100

120

140

160

180

2000 2001 2002 2003 2004 2005 2006 2007

Pre

isin

de

x [

%]

Erzeugerpreis Holzpreis Energiepreis

price development pulp & paper industry

electricity pulpwood publication paper

Fig. 2: price development pulp & paper industry



Introduction (2)

• Picea abies pulpwood shortages on the German wood market

– booming sawing industry

– bioenergy– sivilcultural

management concepts

Is the utilization of alternative tree species like Pinus sylvestris a possible solution for this problem?

Fig. 3: empty woodyard at Stora Enso Reisholz Mill



State of knowledge – wood and fibre properties

• P. sylvestris has in average:– shorter average fibre length than P. abies (Duchesne et al.

1997; Sirviö 2000; Wilhelmsson et al. 2002) but also higher average fibre length is reported (Fengel & Grosser 1976)

– larger fibre diameter than P. abies (Ekenstedt et al. 2003)– larger cell wall thickness and coarseness than P. abies

(Sirviö 2000; Ekenstedt et al. 2003)– higher basic density than P. abies (Loskant 1983; Dinwoodie

1996; Ekenstedt et al. 2003; Fengel & Wegener 2003)– higher extractives content than P. abies (Brandal 1966;

Kamutzki 1983; Fengel & Wegener 2003)



State of knowledge – pulp and paper properties

• Groundwood (of scots pine)– higher yield per m³ due to higher

density– lower strength properties at a

given specific energy consumption (SEC) than P. abies (Blechschmidt et al. 1985; Kärna 1996; Putz & Göttsching 1988)

– slightly lower brightness than P. abies (Putz & Göttsching 1988)

– problems with resin can occur during the grinding and the papermaking process (Blechschmidt et al. 1985; Putz & Göttsching 1988)

Fig. 4: atmospheric chain grinder



State of knowledge – pulp and paper properties

• Thermo-mechanical pulp:– slightly lower strength properties than spruce

assortments (Duchesne et al. 1997)– for strength spruce fibres should be preferred

(Kärenlampi 1992)

• Chemical pulp– slightly lower strength properties than spruce

chemical pulp (Kärenlampi 1992)



Material and Methodology

• Mill scale grinding trials with an atmospheric chain grinder

• Laboratory scale oxidative (hydrogen peroxide) bleaching

• Fiber maceration with acetic acid and hydrogen peroxide (fibre analysis with Mezzo Fibre Lab 3)

Fig. 5: Pinus sylvestris pulpwood



Material and Methodologylogging

storage on wood yard

cut to length/ debarking

marking

stem selction

grinding

pulp sampling

pulp and paperanalysis bleaching

stem selection

fiber macceration

wood analysis

data analysis

Fig. 4: Trial layout



Material and Methodology – wood and fibre properties of Pinus sylvestris and Picea abies

Age Moisture content (%)

Density (g/cm³)

Ring width (mm)

Pinus sylvestris

36 42,1 0,45 1,96

Standard deviation

7 4,1 0,03 0,72

Picea abies 22 47,7 0,40 3,12

Standard deviation

7 7,1 0,04 0,95



Material and Methodology – wood and fibre properties of Pinus sylvestris and Picea abies

Latewood (%)

Juvenile wood (%)

Fibre length (mm)

Fibre width (µm)

Pinus sylvestris

19,5 37,2 3,19 26,0

Standard deviation

3,3 13,3 - -

Picea abies 13,9 71,3 2,86 22,3

Standard deviation

4,7 21,1 - -



Results – pulp and paper propertiesFreeness (Schopper-Riegler)

Relationship between specific energy consumption and freeness (Schopper-Riegler)

68

70

72

74

76

78

80

82

84

1000 1100 1200 1300 1400 1500 1600

specific energy consumption (kWh/t)

free

nes

s (S

R)

Pinus sylvestris Picea abies

Logarithmisch (Pinus sylvestris) Logarithmisch (Picea abies)



Results – pulp and paper propertiesFreeness (SR)

Freeness (Schopper-Riegler) at specific energy consumption of 1.200 kWh/t

71,5

72,0

72,5

73,0

73,5

74,0

74,5

75,0

75,5

Pinus sylvestris Picea abies Picea abies_high density

Fre

enes

s (S

R)



Results – pulp and paper propertiesSheet density (g/cm³)

Relationship between specific energy consumption and sheet density

0,4

0,42

0,44

0,46

0,48

0,5

0,52

0,54

0,56

1000 1100 1200 1300 1400 1500 1600


shee

t d

ensi

ty (

g/c

m³)

Pinus sylvestris Picea abies Linear (Picea abies) Linear (Pinus sylvestris)



Results – pulp and paper propertiesSheet density g/cm³)

Sheet density at specific energy consumption of 1.200 kWh/t

0,380

0,400

0,420

0,440

0,460

0,480

0,500

0,520


Sh

eet

den

sity

(g

/cm

³)



Results – pulp and paper propertiesTensile Index (Nm/g)

Relationship between specific energy consumption and tensile index

20

25

30

35

40

45

50

1000 1100 1200 1300 1400 1500 1600


ten

sile

ind

ex (

Nm

/g)

Pinus sylvestris Picea abies Linear (Picea abies) Linear (Pinus sylvestris)



Results – pulp and paper propertiesTensile Index (Nm/g)

Tensile index at specific energy consumption of 1.200 kWh/t

0,0

5,0

10,0

15,0

20,0

25,0

30,0

35,0

40,0

45,0


Ten

sile

ind

ex (

Nm

/g)



Results – pulp and paper propertiesPorosity (Bendtsen)

Porosity (Bendtsen) at specific energy consumption of 1.200 kWh/t

0

50

100

150

200

250

300

350


Po

rosi

ty (

ml/m

in)



Results – pulp and paper propertiesISO-brightness

ISO-brigthness at specific energy consumption of 1.200 kWh/t

61,0

62,0

63,0

64,0

65,0

66,0

67,0

68,0


ISO

-bri

gh

tne

ss



Results – pulp and paper propertiesBleachability with hydrogen peroxide

Bleachability of Pinus sylvestris and Picea abies groundwood pulp

0

10

20

30

40

50

60

70

80

90

ISO-Brightness(unbleached)

ISO-Brightness (bleached) delta

ISO

-Bri

gh

tnes

s (%

)

(Bleaching with 4% hydrogen-peroxide, bulk density 25%, bleaching duration 2 hours)

(Bleaching experiment with frozen groundwood - lower ISO brightness because of this)



Results – pulp and paper propertiesSpecific energy consumption (kWh/t)

Specific energy consumption required to reach freeness 75 SR

1000

1100

1200

1300

1400

1500

1600

1700

68 70 72 74 76 78 80 82 84

Freeness (SR)

spec

ific

en

erg

y c

on

sum

pti

on

(k

Wh

/t)

Pinus sylvestris Picea abies

Exponentiell (Pinus sylvestris) Exponentiell (Picea abies)



Results – pulp and paper propertiesSpecific energy consumption (kWh/t)

Specific Energy Consumption at Freeness 75 SR

1100

1150

1200

1250

1300

1350


Sp

ecif

ic E

ner

gy

Co

ns

um

pti

on

(kW

h/t

)



Discussion

• pulp and paper quality of Pinus sylvestris pulpwood can be explained due to:

– fibre morphology– chemical properties

• lignin content• extractives



Discussion

• fibre morphology– fibre width

• reduced tensile index with increasing fibre width (Kärenlampi 1992; Corson 1999)

• higher porosity with increasing fibre width (Kärenlampi 1992; Corson 1999)

– cell wall thickness• fibres of P. sylvestris are stiffer than fibres of P. abies and

break in a earlier stage in the grinding process and result in low pulp fibre length and low tear strength



Discussion

• chemical properties– lignin content

• due to the higher lignin content a higher amount of energy and/or heat is required during the grinding process (Sundholm et al. 1999)– the grinding process has to be adjusted for P. sylvestris– differences between P. sylvestris and P. abies diminish when

using the PGW process (Kärna 1986)

– extractives• high amount of extractives cause low strength properties

(Brandal 1966)• extractives (Pinosylvin) induce lower pulp brightness

(Blechschmidt et al. 1985)



Conclusion

• P. sylvestris can be used as a raw material for the groundwood process but the pulp and paper quality is lower than using P. abies

• due to the different fibre morphology and the different chemical properties the process technology should be adjusted

• the utilization of P. sylvestris pulpwood can be advantageous as a result of:

– better availability– lower purchasing price– higher yield



Thanks for your attention

Götz Martin

Institute of Forest Utilization and Work Science


Tel: 0049-761 - 203 9242

E-Mail: [email protected]




Fig. 5: Marked (spruce) pulpwood




Fig. 6: Log saw

Fig. 7: Debarking drum




Fig. 8: Stem selection




Fig. 9: Atmospheric chain grinders at Stora Enso Reisholz mill




Fig. 10: Pulp sampling




Fig. 11: Pulp and paper analysis

Documents

IUFRO All-Division-5 Conference “Forest Products and Environment – A Productive Symbiosis”