1. IMPROVING BLEACHING PERFORMANCE OF SULPHITE DISSOLVING PULPS
XXII TECNICELPA – International Forest, Pulp and Paper Conference
IMPROVING BLEACHING PERFORMANCE OF SULPHITE DISSOLVING PULPS
Leonardo Lourenço de Jesus (CICECO-UA)
Professor Dmitry V. Evtyugin (CICECO-UA)
Engineer António F. d. S. Prates (CAIMA S.A.)
Tomar, 3th October 2013

2. 2
CONTENTS
Introduction;
Objectives;
Experimental methodology;
Results and discussions;
Main conclusions

3. 3 INTRODUCTION Cellulose (Beyond paper) Main applications: Textiles;
Cellophane;
Rayon;
Composites;
Films;
Varnish;
Plastics
Produced from:
Cotton;
Dissolving pulp of wood species
Main cellulosic derivatives:
Viscose;
Cellulose acetates

4. 4 INTRODUCTION Source: textileworld.com Source: apparel.edgl.com
Source: Indexmundi

5. 5
INTRODUCTION
To be considered as dissolving pulps, cellulosic pulps must satisfy these requisites:
High α-cellulose content (≥ 91%);
Less Kappa number (≈ 1);
Moderate intrinsic viscosity ([ ] cm3/g)
Low amount of hemicelluloses and extractives compounds;
High reactivity (> 60%)

6. 6 INTRODUCTION At CAIMA S.A: Where:
Cooking process: Acid sulphite with Mg base
Bleaching sequence: EOPEP
Where:
EOP Stage :
Delignification and bleaching action;
Actually works as unique delignificant stage;
EP Stage:
Bleaching action

7. 7
INTRODUCTION
Table 1- Characteristics of conventionally EOPEP bleached sulphite pulp
Stage EOP
Stage EP IK
9,1
8,5
[η] (cm3/g)
1150
1120
Pentosans (%)
Not applicable
5,8
Lignin (%)
1,6
Brightness ISO (%)
80,4
87,2
This E. globulus pulp obtained from TCF sulphite pulp cannot be classified as dissolving pulp.

8. 8
OBJECTIVES
Study the modification of CAIMA’s bleaching sequence to obtain dissolving pulp as final product (EEOPEP vs EOEP);
Characterize this pulp to study the ability for cellulosic derivatives production (namely viscose and cellulose acetate)

9. EXPERIMENTAL METHODOLOGY9
EXPERIMENTAL METHODOLOGY
Parameter caractherized
Significance
Standard/Test
Moisture
Determination of moisture on different pulps
TAPPI T 412 om-06
Consistency
Determination of pulp’s consistency
TAPPI T 240 om-07
Neutral sugars
Amount of neutral sugars
Analysis of neutral sugars by acid hydrolisis
Kappa number
Extension of pulp’s delignification
TAPPI T 236 om-09
Intrinsic viscosity
Extension of pulp’s degradation
SCAN-CM 15:88
Hemicelluloses
Determination of maximum percentage of solubilized cellulose and hemicelluloses (R10);
Determination of total percentage of solubilized hemicelluloses (R18)
TAPPI T 235 cm-00
Chemical oxygen demand
Degree of organic compounds oxidation
ASTM D (reflux method)
α-cellulose
Determination of α-cellulose amount on final pulps (R17,5)
TAPPI T203 cm-99
Reactivity
Ability of reaction of final pulps with CS2
Fock method
Brightness
Degree of cromophores compounds elimination
ISO 2470:1999
Pentosans
Determination of pentosans by bromite-bromade method
TAPPI T223 cm-10
Extractives
Determination of extractive compounds with acetone
TAPPI T207 cm-97

10. RESULTS AND DISCUSSION10
RESULTS AND DISCUSSION
Characterization of Pulp 1 and Pulp 2
Table 3- Results of Pulp 1 and Pulp 2 characterizations
Parameter caractherized
Pulp 1
Pulp 2
Kappa number
11,0
6,6
Intrinsic viscosity (cm3/g)
740
585

11. RESULTS AND DISCUSSION Intrinsic viscosity (cm3/g)11
RESULTS AND DISCUSSION
E stage optimization (EEOPEP vs EOEP)
Table 5- Results on Pulp 1 after treatment in E stage
Table 6- Results on Pulp 2 after treatment in E stage
Table 4- Operation parameters applied in E stage
Temperature (⁰C)
Alkali charge (% odp)
Yield (%)
Kappa number
Intrinsic viscosity (cm3/g)
R10 (%)
R18 (%)
COD (mg O2/ Kg odp) 70 2
97.5
5.7
730
89.5
90.0
20500 3
5.2
725
90.2
91.6
21500 80
5.5
90.5
92.1
25500
96.0
5.1
715
89.7
92.3 4
92.5
710
90.8
93.4
31500 5
700
89.2
90.9
46500 90
5.8
720
90.7
87.7
Temperature (⁰C)
Alkali charge
(% odp)
Yield (%)
Kappa number
Intrinsic viscosity
(cm3/g)
R (%)
R (%) 90 4
89.0
2.4
675
91.9
94.7 6
85.0
2.3
690
92.1
94.8
110
77.5
710
95.8
75.0
2.7
730
94.0
95.9
Sample
Temperature (⁰C)
Alkali charge
(% odp)
Pulp 1
70; 80; 90
2-5
Pulp 2
90;110
4.0; 6.0
Criteria to choose optimal conditions:
High yield;
Low Kappa number;
High R10 and R18;
Low intrinsic viscosity

12. RESULTS AND DISCUSSION Intrinsic viscosity (cm3/g)12
RESULTS AND DISCUSSION
EOP stage vs O stage (EEOPEP vs EOEP)
In order to select the second stage with less modification of actual CAIMA’s bleaching sequence, 2 alternatives were studied with Pulp 1:
EOP (Actual delignificant and bleaching stage at current CAIMA’s EOPEP bleaching sequence);
O (Alternative stage)
Table 8- Results on pulps’ delignification in EOP and O stages
Table 7- Operation parameters for EOP and O stages
EOP O
Temperature (°C) 80
105
Alkali charge (% NaOH)
2.1
2.5
H2O2 charge (% H2O2)
1.2
Not applicable
O2 (bar) 3 6
Time (h) 1
Stage
Yield (%)
Kappa number
Intrinsic viscosity (cm3/g)
R10 (%)
R18 (%)
EOP
87.5
2.7
455
95.3
97.2 O
92.5
2.6
710
95.6
98.7
Due to low intrinsic viscosity, the EOP stage was excluded and the O stage was selectionated as delignificant stage

13. RESULTS AND DISCUSSION13
RESULTS AND DISCUSSION
Optimization of O stage (EOEP)
Table 10- Results on oxygen delignification of Pulp 1 (105 °C)
Table 9- Conditions applied in O stage
Table 11- Results on oxygen delignification of Pulp 2 (oxygen pressure 5 bar)
Time
(h)
Alkali charge (% odp)
Temperature
(°C)
Yield
(%)
Kappa number
Intrinsic viscosity (cm3/g)
R10 (%)
R18 (%)
0.5
2.8 95
85.5
1.5
655
93.1
95.2
1.0
80.5
1.2
630
95.1
97.6
105
79.5
1.6
690
93.0
96.0
2.3
76.6
2.1
620
92.4
94.0
Temperature (⁰C)
Alkali charge (% odp)
O2 pressure (bar)
Time (h)
Pulp 1
105
2.5; 2.8
6; 8
1; 1.5
Pulp 2
95;105
2.3; 2.8 5
0.5; 1
Time (h)
O2 pressure (bar)
Alkaline charge (% odp)
Yield (%)
Kappa number
Intrinsic viscosity
(cm3/g)
R10 (%)
R18 (%) 1 6
2.5
92.5
2.6
710
96.6
98.7
2.8
92.0
2.2
680
96.7
98.9 8
90.0
670
89.5
1.6
640
95.4
98.4
1.5
87.5
87.0
570
95.9
98.5
Criteria to choose optimal conditions:
High yield;
Low Kappa number;
High R10 and R18;
Low intrinsic viscosity

14. RESULTS AND DISCUSSION14
RESULTS AND DISCUSSION
Study of EP stage (EOEP)
Table 13- Results on the bleaching of Pulp 1 in the last EP stage (H2O2 load of 1.0%)
Table 14- Results on the bleaching of Pulp 2 in the last EP stage
Table 12- Conditions applied in EP stage
H2O2 charge
(wH2O2/wodp)
Yield
(%)
Kappa number
Intrinsic viscosity
(cm3/g)
R10
R18
1.0
84.5
1.3
520
91.3
94.5
1.4
77.5
1.1
470
91.8
95.2
Temperature
(⁰C)
Alkali charge
(% odp)
H2O2 charge
Time
(h) 80
1.0
1.0; 1.4
2.5
Yield
(%)
Kappa number
Intrinsic viscosity
(cm3/g)
R10
R18
89.5
0.9
500
96.7
98.9

15. RESULTS AND DISCUSSION15
RESULTS AND DISCUSSION
Final pulp characterization
Table 15- Results of analysis of pulps bleached by EOEP
Fully bleached pulp
Pentosans (%)
Extractives (%)
α-cellulose (%)
Brightness (%)
Reactivity index
Pulp 1
2.0 -
96.8
89.4
72.2
Pulp 2
3.2
0.40
93.2
90.1
68.0

16. 16
CONCLUSIONS
For incoming sulfite E. Globulus pulps with Kappa number between 6-11, the bleaching sequence EOEP showed best results than EEOPEP ;
At first E stage, the optimal conditions are:
Temperature: 80-90°C;
Time: 1h;
Alkali load: 3-4%
On this first stage, ca % of residual lignin and cooking-degraded low molecular weight polysaccharides were removed without significative loss of pulp viscosity;
On O stage, the optimal conditions for Pulp 1 (T=105 °C, t=1 h, P(O2)=8 bar) were more drastic than Pulp 2 (T=95 °C, t=0,5 h, P(O2)=5 bar);
The main consequence was a major delignification on Pulp 1 (ca. 70%) than on Pulp 2 (ca. 40%);

17. 17
CONCLUSIONS
At EP stage, the optimal conditions are very similar relatively the conditions that are used on actual CAIMA’s EOPEP bleaching sequence. The optimal conditions are:
Temperature= 80°C;
Time= 2.5h;
Alkali load= 1.0% odp;
H2O2 charge= 1.0% odp
Both pulps (Pulp 1 and Pulp 2) bleached from EOEP can be classified as dissolving pulps because:
Kappa number ≈ 1;
Intrinsic viscosty ≈ 500 cm3/g;
Brightness ≈ 90 % ISO;
Low pentosans content (2-3 %);
High amount of α-celulose (93-95 %);
Reactivity ≈ 70 %

18. Thanks for your attention18
FINALLY…
Thanks for your attention