Optimized ECF
Bleaching Sequence Studies
Softwood Kraft Brownstock
Art J. Ragauskas
Project Goals
Sequences Examine
D/C(EO)DED*
D/Z(EOP)DED
D/Z(EOP)D/Z(EP)D
ZQ(PHT)Z(PHT)
OZQ(PHT)
-softwood
OD(EOP)D*
OZ/D(PHT)D
OZ/D(PHT)D/Z
OZ(PHT)D
OZQ(PHT)Z(PHT)
Results D/C(EO)DED: Softwood
Bleaching Conditions
D/C - 50% ClO2 Substition
KF 0.20, SW Kappa# 33.3
10% Black liqour carryover
3.5% csc, 50C, 45 min.
EO - 3.6% NaOH, 75C, 75 min
O2=35 psi 15 m in, 10% carryover
D1 - 1.0% ClO2, 75C,180 min
10% carryover, 10% csc
E - 75C, 60 min, 10% carryover, 10%csc
0.5% NaOH
D2
0.4%, 0.6%, 0.8%, 1.0% ClO2
75C, 180 min., 10% csc
TAPPI Brightness
Results D/C(EO)DED: Softwood
Bleaching Results
100
90
80
70
60
50
40
30
20
10
0
D/C
(EO)
D1
D2 (0.4%)
D2 (0.6%)
D2 (0.8%)
D2 (1.0%)
Results OD(EOP)D: Softwood
Bleaching Conditions
02
- initial washed kappa # 30.4
carryover
2.0% NaOH, 110C
30 min, 60 psi O2
D1 - 0.22 KF (incoming kappa#=15.0)
O2=35 psi 15 m in, 10% carryover
50C, 60 min
(EOP) - 1.82% NaOH, 0.4% H2O2
90C, 60 min., 10% carryover
35 psi O2/15m in
D2- 75C, 180 min, 10% carryover, 10%csc
0.6%, 0.8%, 1.0%, 1.2% ClO2
D2
0.4%, 0.6%, 0.8%, 1.0% ClO2
75C, 180 m in., 10% csc
Results OD(EOP)D: Softwood
Bleaching Results
TAPPI Brightness
90
80
70
60
50
40
D1
(EOP)
D2 (0.6%)
D2 (0.8%)
D2 (1.0%)
D2 (1.2%)
Results OD(EOP)D: Softwood
Bleaching Results
89
TAPPI Brightness
88
87
86
85
84
83
82
81
80
D2 (0.6%)
D2(0.6%) D(0.25%)
D2(0.6%) D(0.5%)
D2(0.8%)
D2(0.8%) D(0.25%)
D2(0.8%) D(0.5%)
D2(1.0%)
D2(1.0%) D(0.25%)
D2(1.0%) D(0.5%)
D2(1.2%)
D2(1.2%) D(0.25%)
D2(1.2%) D(0.5%)
Results (D/Z) vs. (Z/D):
Softwood before O2
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General Bleaching Conditions
– 50oC
– 0.20 KF
» 50% Z subst.
» pHinitial:2.5
» 10% carryover
Kappa #
Results (D/Z) vs. (Z/D) at 3.5% CSC:
Softwood before O2
35
33
31
29
27
25
23
21
19
17
15
Brownstock
D/Z after D
D/Z
Brownstock
Z/D after Z
Z/D
Kappa #
Results (D/Z) vs. (Z/D) at 10% CSC:
Softwood before O2
35
33
31
29
27
25
23
21
19
17
15
Brownstock
D/Z after D
D/Z
Brownstock
Z/D after Z
Z/D
Research Issues
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Direction on D/Z
– pre-O2 >> D/Z
– post-O2 >> Z/D
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Secondary Z stages to be at 10%
csc
Brightness target
– OD(EOP)DD
Studies Directed on
D/Z(EOP)DED & D/Z(EOP)Z/D(EP)D
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D/Z(EO)DED
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D/Z(EOP)Z/D(EP)D
– D/Z 0.2 kf
– D/Z 0.2 kf
» 50% Z sub
» 50% Z sub
– EOP
» 0.4 & 0.8% P
– D1 0.8% charge
– E
– D2
» 0.2, 0.4, 0.6, 0.8%
» charge
– EOP
» 0.5 & 1.0% P
– Z/D
» 0.2% consumed
» 0.5% ClO2
– D2
» 0.2, 0.4, 0.8% ClO2
Kappa and ISO Brightness After D/Z (0.20 kf, 50% Sub., 50C, 10kg/ton carryover) &
Eop (%NaOH=0.5 TAC, 90C, 10% carryover, 20 psi O2 at 15 min, 0 psi at 60 min)
7.7
51
Kappa #
Brightness
50
49
7.4
48
7.3
47
7.2
46
7.1
45
Kappa #
7.5
0.4% P
0.5% P
0.8% P
Charge of P in (EOP)
1.0% P
ISO Brightness
7.6
Brightness Changes for Bleaching Four (D/Z)(EOP) Pulps with DED
D1 employed 0.8% ClO 2 and D 2 employed either 0.6% or 0.8% ClO 2
90
ISO Brightness
85
80
75
Eop 0.4%P
70
Eop 0.5% P
Eop 0.8%P
Eop 1.0% P
65
Bleaching Stage
60
(D1 Charge= 0.8%
ClO2)E
D2 Charge=0.6% ClO2
D2 Charge=0.8% ClO2
Brightness Changes for Bleaching (D/Z)(EOP) Pulps with DED
D1 employed 1.2% ClO2 and D2 employed either 0.6% or 0.8% ClO2
90
85
ISO Brightness
80
75
70
Eop 0.5% P
Eop 1.0% P
65
60
(D1 Charge=
1.2% ClO2)E
D2
Charge=0.6%
ClO2
Bleaching Stage
D2
Charge=0.8%
ClO2
Studies Directed on
OZ(PHT)D & OZQ(PHT)Z(PHT)
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OZ(PHT)D
– Z
» 0.3 & 0.5% Z
consumed
– PHT
» 1.0 & 2.0% P
– D
» 0.2, 0.4, 0.6, 0.8%
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OZQ(PHT)
– Z
» 0.3% consumed
– PHT
» 1.0 & 2.0% P
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OZQ(PHT)Z(PHT)
– Z
» 0.3% Z consumed
– Q
– PHT
» 1.0 2.0% P
– Z
» 0.3% Z consumed
– PHT
» 1.0, 1.5% P
OZ(PHT)Z(PHT) Studies
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O-stage
Z-stage - 0.3% consumed, pH 2.2
– 50C
Q - DTPA
1.0% H2O2 - 1.3%NaOH
K
– term. pH 9.4
a
– ISO bright. 42.3
p
2.0% H2O2 - 2.6% NaOH
p
a
– term. pH 9.4
– ISO bright. 46.1
#
Z-stage 0.3% consumed pH 2.2
1.5% H2O2 - 2.0% NaOH
– term. pH 9.2
– ISO brightness 70
35
30
25
20
15
10
5
0
OZ(PHT)D Studies
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O-stage
Z-stage
– 0.3% consumed, pH 2.2
– 50C
1.0% H2O2 - 1.0%NaOH
– term. pH 9.2
– ISO bright. 41.3
2.0% H2O2 - 2.0%NaOH
– term. pH 9.2
– ISO bright. 43.6
35
30
K
25
a
p 20
p
a 15
#
10
5
0