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Optimizing ECF Bleaching Technologies with a Poor Man’s O Lucian A. Lucia T. J. Dyer, D. Johnston, A.J. Ragauskas Institute of Paper Science and Technology

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Optimizing ECF Bleaching Technologies with a Poor

Man’s O

Lucian A. LuciaT. J. Dyer, D. Johnston, A.J. Ragauskas

Institute of Paper Science and Technology

Oxygen Delignification

0

50

100

150

200Million

Tons

1983 1986 1994 2000

Chemical Usage of North American Bleach Plants

Chlorine Chlorine Dioxide O Delign.

Improved environmental and operating cost performance

O Delignification: Background

0

100

200

300

400

500

600

700

Cita

tions

1965

-7019

70-75

1975

-8019

80-85

1985

-9019

90-95

1995

-99

Literature• 1960/70s

– basic engineering & chemistry• 1980/early 90s

– process parameters, energy, environmental, pretreatments, fundamental chemistry, pulp properties

• Late 1990’s – yield, selectivity, process

parameters, lignin/carbohydrate chemistry, catalysts

Oxygen DelignificationIncreased interest in one and two-stage oxygen delignification

38394041424344454647484950

0 10 20 30 40 50 60

Pulp

Yiel

d, %

.

30 ECF

30 (O)40 (OO)

50 (OO)

Kraft

KAPPA

DEopD

DEopD

Yield and Operating Benefits

An Alternative Approach

• Mini-O– Removes less lignin– Less capital– Easily retrofitted

• Enhanced Mini-O– Greater lignin removal– Multiple stages– H2O2 and/or ClO2

Mill Application• McKenzie

– Cook to normal target• Reduce lignin with O2

– Sodium hydroxide instead of oxidized white liquor

• Low AOX pulps– No production loss– No recovery bottleneck– 25% delignification

Recent Studies• Chakar, et al.

– Compared O systems

• O, OO, mini-O

– Split the caustic charge in a (E+O)D(E+O)

– Delignification • Lowest for mini-O

– 13-25%, depending on caustic addition

BS

NaOH: 1

.5%

NaOH:2.

5%

NaOH:3.

5%

OO

O(E+O)D((E+O)

(E+O)

0

5

10

15

20

25

30

Kap

pa #

Recent Studies• Chakar, et al.

– Viscosities• O vs. (E+O)D(E+O)

– Same delignification at 3.5% as O at 1.5%

• Improved viscosity

Low Kap

pa BS

L-1.5%

L-2.5%

L-3.5%

BS

OOO(E+O)D(E+O)

0

5

10

15

20

25

30

Vis

cosi

ty/c

P

Recent Studies• Chakar, et al

– Does not mimic actual bleach plant conditions

– Need to investigate impact of interstagewashing and carryover on mini-O system

(E+O)(E+O+P)

(E+O)D(E+O)* Delignification Results

Mini-O Delignification Studies

Research Objective

• Examine impact of carryover• 26.3 Kappa SW kraft• Determine

– Physical properties– Selectivity

• Contribute to future mini O-delignification road map to improve performance

Mini-O Delignification: Experimental Design

Bleaching Sequences

• (E+O)(E+O)• D(E+O)• (E+O)D(E+O)• D(E+O)(E+O)

BL Carryover

• No carryover• 2 kg/ton• 10 kg/ton

Experimental Conditions

7080/70/801.25/0/1.2590/0/90(E+O)D(E+O)

3070--D0.05, 0.20

20801.2590(E+O)

Time/min.Temp./oC% NaOHO-Press./psiStage

10% consistency

MgSO4: 0.10%

Impact of Carryover

• Carryover decreases delignification

• Increased levels– Decreased

response

• Splitting (E+O)– Improved

response

D0.20(E

+O)(E+O)

(E+O

)D0.2

0(E+O)

D0.20(E

+O)

D0.05(E

+O)(E+O)

(E+O

)D0.0

5(E+O)

D0.05(E

+O)(E

+O)(E

+O)

10 kg/ton2 kg/ton

no carryover30

40

50

60

70

80

90

100

% D

elig

nific

atio

n

Impact of Carryover

• Viscosity loss– Increases as

function of carryover

• Carryover– May introduce

transition metals

• Placement of (E+O)– Affects viscosity

loss

D0.20(E

+O)(E

+O)

(E+O

)D0.2

0(E+O

)D0.2

0(E+O

)

D0.05(E

+O)(E

+O)

(E+O

)D0.0

5(E+O

)D0.0

5(E+O

)(E

+O)(E

+O)

no carryover

2 kg/ton

10 kg/ton10

15

20

25

30

35

% V

isco

sity

Los

s

Impact of Carryover

• Selectivity– Decreases as

function of carryover

• Carryover– May introduce

transition metals

• Placement of (E+O)– Affects

selectivity

D0.20(E+O

)(E+O

)

(E+O)D

0.20(E+O

)D0.20(E

+O)

D0.05(E+O

)(E+O

)

(E+O)D

0.05(E+O

)D0.05(E

+O)

(E+O)(E

+O)

10 kg/ton

2 kg/ton

no carryover0123456

Sele

ctiv

ity

Mini-O with H2O2 Studies

Research Objective

• Examine impact of carryover• Three SW kraft pulps

– 26.3 Kappa pre-O2

– 24.3 Kappa pre-O2

– 8.9 Kappa post-O2

• Determine – Physical properties– Selectivity

• Contribute to future mini O-delignification road map to minimize capital and enhance performance

Mini-O with H2O2 Delignification: Experimental Design

Bleaching Sequences

• O• D(E+O)• D(E+O+P)• (E+O)*D(E+O)*• D(E+O)*(E+O)*

Pulps

• Pre-Oxygen– 26.3 kappa

• Pre-Oxygen– 24.2 kappa

• Post-Oxygen– 8.9 kappa

Experimental Conditions

20801.2590(E+O+P)

7080/70/801.25/0/1.2590/0/90(E+O)*D(E+O)*

3070--D0.05, 0.20

20801.2590(E+O)

Time/min.Temp./oC% NaOHO-Press./psiStage

10% consistency BL carryover: 10 kg/ton

H2O2 : 0.5% MgSO4: 0.10%

Mini-O Reinforced with H2O2• Carryover at 10

kg/ton– Decreased

response

• Pre-O2 vs. Post-O2– Decreased

response in post-O2

• Delig. Response– Proportional to

H2O2

• (EO)*D0.05(EO)*

D0.20(E

OP)D0.2

0(EO)

(EOP)D

0.05(E

OP)

(EOP)D

0.05(E

O)

(EO)D

0.05(E

OP)

(EO)D

0.05(E

O)D0.0

5(EOP)

D0.05(E

O)

O

post-O2 w ith c/opre-O2 w ith c/opre-O2

20

30

40

50

60

70

80

90

100

% D

elig

nific

atio

n

Mini-O Reinforced with H2O2

• Carryover at 10 kg/ton– Generally

decreases viscosity loss

• Pre-O2 vs. Post-O2– Greater loss for

pre-O2 pulp

• Increased H2O2– Increased

viscosity loss

D0.20(E

OP)D0.2

0(EO)

(EOP)D

0.05(E

OP)

(EOP)D

0.05(E

O)

(EO)D

0.05(E

OP)

(EO)D

0.05(E

O)D0.0

5(EOP)

D0.05(E

O)

O

post-O2 w ith c/opre-O2 w ith c/o

pre-O25

10

15

20

25

30

35

% V

isco

sity

Los

s

Mini-O Reinforced with H2O2

• Carryover at 10 kg/ton– Generally

decreases selectivity

• Pre-O2 vs. Post-O2– Greater

selectivity for pre-O2 pulp

D0.20(

EOP)D0.2

0(EO)

(EOP)D

0.05(E

OP)

(EOP)D

0.05(E

O)

(EO)D

0.05(E

OP)(E

O)D0.0

5(EO)

D0.05(E

OP)D0.0

5(EO)

O

post-O2 w ith c/opre-O2 w ith c/o

pre-O20

1

2

3

4

5

6

Sel

ecti

vity

Mini-O Reinforced with H2O2

• Carryover at 10 kg/ton– Generally

decreases brightness response

• (EO) vs. (EOP)– Exiting

bleaching stage

D0.20(E

OP)D0.2

0(EO)

(EOP)D

0.05(E

OP)

(EOP)D

0.05(E

O)

(EO)D

0.05(E

OP)

(EO)D

0.05(E

O)D0.0

5(EOP)

D0.05(E

O)

O

post-O2 w ith c/opre-O2 w ith c/o

pre-O20

20

40

60

80

100

120

140

160

180

% B

right

ness

Gai

n

Conclusions

Mini-O Delignification:Implications

• Superior performance with pre-O2 pulps when compared to post-O2pulps

• Benefits of enhanced poor man’s O

• H2O2 in last stage of (EO)*D(EO)*– Increased bleaching

performance

• Promising technology

IPST Member CompaniesU.S. Department of Energy

Cooperative Agreement DE-FC07-00ID13870

[email protected]