Evaluation of ECF Bleached SW Kraft Pulps From Mature and Thinning Softwood Resources A.J. Ragauskas, B.R. Carter, C.C. Courchene, D.H. Kim Institute of Paper Science and Technology, Georgia Institute of Technology
Background Georgia has the highest collection of non-industrial private forest landowners (NIPF) in the nation NIPF are a primary source of wood for many of Georgia s pulp mills. NIPF owners have begun to utilize short-rotation management options to improve the feasibility, profitability, and cash flow of production forestry enterprises. A valuable component in forestry management approaches is to cut immature trees to stimulate growth/yield of the remaining trees University of Georgia have demonstrated that thinning loblolly and slash pine stands increased internal rate of return for NIPF landowners by 1½% (slash) to 2% (loblolly) over unthinned stands. Hence economical factors will increase the availability of pine thinnings for kraft pulping operations Potential cost savings of 15 30%
Background The physical performance of kraft pulps bleached/unbleached from thinnings vs. mature wood remains an issue of practical importance Zobel, McGovern, and Koch documented (1970-81) that southern softwoods from fast-grown plantations are different from that from older, natural stands of the same species because of age, tree form and quality Hatton et al. (1996) demonstrated that kraft pulps prepared from black, Norway, red and white spruce thinnings exhibited reduced tear properties, but excellent tensile properties which were attributed to the thinner cell walls from the juvenile wood. Drost et al. reported (2004) on variations in fiber characteristics from mature and juvenile wood from whole-log and sawmill chips pulps from juvenile wood had superior beatability resulting from their lower coarseness, while pulps from mature wood exhibited higher tear as a result of their greater fiber lengths.
Program Objectives Assess the impact of SW thinnings for the production of bleached kraft pulp for modern southern SW pulp mill operations. Year 1: Examined SW kraft pulps Year 2: Examined ECF SW kraft pulps
Research Objectives Experimental: Kraft Cooking Process Ratio of Thinnings:Mature Wood Employed Conventional batch 100:0, 80:20, 40:60, 0:100 Simulated ITC 100:0, 60:40, 0:100 The kraft pulps will be bleached to TAPPI brightness ~85 via two bleaching sequences: OD(E+P+O)D D(E+P+O)DED The partially bleached pulps will be analyzed for kappa number, viscosity, and TAPPI brightness The fully bleached pulps will be analyzed for optical, chemical, and physical strength properties Fully bleached pulps will also be PFI refined with 2000, and 4,000 revs and the physical strength properties will be re-assessed at each point of refining
Wood Results Wood Chips Properties for Thinning vs. Mature Density Klason Lignin Extractives Earlywood:Latewood Thinning 0.423 29.8 2.77 1.0:0.89 Mature 0.448 28.5 1.93 1.0:1.53 Carbohydrate Profile (%) Gluc. Galact. Mann. Xylan. Arabinan Thinning 64.9 4.5 16.9 10.6 3.1 Mature 67.9 3.5 17.7 8.8 2.1
Mature and Thinning Softwood Resources: Pulping Results Total and Screened Yields for Conventional Kraft Pulping Pulp Yields 46 45.8 45.6 45.4 45.2 45 44.8 44.6 44.4 Cook Type Conventional Kraft SW Chips Thinning: Mature 100:0 0:100 80:20 60:40 Final H-factor 1,436 1,445 1,438 1,434 44.2 44 Total Yield 40:60 1,433 Thinning (T) Mature (M) 80:20 T/M 60:40 T/M 40:60 T/M Screened Yield
Mature and Thinning Softwood Resources: Pulping Results Kappa # for Conventional Kraft Pulps 28 26 24 Kappa # 22 20 ` 18 16 Thinning (T) Mature (M) 80:20 T/M 60:40 T/M 40:60 T/M
Background Kappa Number for Lab-Simulated Continuous Kraft Cook Kappa # Screened Yield % Cook Type SW Chips Thinning : Mature Final H-factor 50 45 40 35 30 Modified Continuous Kraft 100:0 0:100 1,717 1,713 25 20 15 10 5 0 Screened Yield % 60:40 1,709 100% Thin. 100% Mature 60:40 Thin/Mat Kappa #
Mature and Thinning Softwood Resources: Pulp Results Tear Index (mnm 2 /g) Tensile Index (N/mm) TEA (J/m 2 ) Zero-Span Tensile Index (N/mm) Conventional Kraft 100% Thinning (T) 13.6 91.1 2098 163 100% Mature (M) 16.8 88.2 1748 174 80:20 (T:M) 14.6 92.2 1968 164 60:40 (T:M) 14.4 88.7 1707 173 40:60 (T:M) 15.7 90.1 1862 172 Modified continuous Kraft 100% Thinning (T) 15.6 85.4 1870 164 100% Mature (M) 19.9 73.2 1170 174 60:40 (T:M) 16.6 86.8 1860 171
Mature and Thinning Softwood Resources: Experimental Protocol OD(E+P+O)D O-Stage (Incoming brownstock kappa # 24-27) 60 min, 100 o C, 10% csc, 90 psig O 2 Caustic charge varied 1.0 1.8 preferred value ~1.5% NaOH to yield post-o kraft pulps with kappa # ~ 10 D o -Stage 45 min, 50 o C, 3.5% csc, Kf 0.25, terminal ph 2.1 2.3 (E+P+O)-Stage 60 min, 75 o C, 10% csc, 0.4% H 2 O 2, initial O 2 :65 psig 15 min; then vent12 psig/5 min, %NaOH 50% of Kf D 1 -Stage 180 min, 75 o C, 10% csc, ClO 2 charge 0.5 2.0%, terminal ph 3 Final TAPPI Brightness Values ~ 87
Bleaching Results OD(E+P+O)D TAPPI Brightness Properties Conventional ITC Mature 87.6 87.2 Thinning 87.2 87.5 60% Thin/40% Mature 87.4 40% Thin/60% Mature 87.3 80% Thin/20% Mature 87.7
Bleaching Results OD(E+P+O)D Fiber Properties: Fiber Length ITC 4.00 FQA Length (mm) 3.00 2.00 1.00 0.00 Mature 60% Thinning Thinning Weight Weighted Length Weighted
Bleaching Results OD(E+P+O)D Fiber Properties: Fiber Length Conventional FQA Length (mm) 4.00 3.50 3.00 2.50 2.00 1.50 1.00 0.50 0.00 Thinning 40% Thin 80% Thin. Mature Weight Weighted Length Weighted
Bleaching Results OD(E+P+O)D Fiber Properties: Fines 10.0 % Fines (Arithemetic) 8.0 6.0 4.0 2.0 0.0 ITC:Mature ITC: 60% Thinning ITC: Thinning Thinning 40% Thin 80% Thin. Mature
Bleaching Results OD(E+P+O)D Fiber Properties: Fiber Charge 0.0300 mmol Acid goup/gr pulp 0.0250 0.0200 0.0150 0.0100 0.0050 0.0000 ITC:Mature ITC: 60% Thinning ITC: Thinning Thinning 40% Thin 80% Thin. Mature
Bleaching Results OD(E+P+O)D Sheet Properties 70 14 60 12 Tensile Index (Nm/g) 50 40 30 Tear Index (mnm2/g) 10 8 6 4 20 2 ITC: Thin 10 4000 0 ITC 60% T 0 ITC:Mature ITC 60% T ITC: Thin 0 2000 Revolutions 0 1 2000 2 3 4000 ITC:Mature
Bleaching Results Sheet Properties: Conventional Kraft Pulps 80 70 60 Tensile Index 50 40 30 20 10 4000 revs 0 2000 revs Thin 80% T 40% T Mature O Revs
Bleaching Results Sheet Properties: Conventional Kraft Pulps 2500 2000 TEA Index 1500 1000 500 4000 Revs 0 2000 Revs Thin 80% T 40% T Mature O Revs
Bleaching Results Sheet Properties: Conventional Kraft Pulps 16 14 12 10 Tear Index 8 6 4 2 0 80% T 40% T Mature 10 2000 2 40003 Thin
Experimental Protocol D(E+P+O)DED D-Stage (Incoming brownstock kappa # 24-27) K.f.:0.20, 45 min, 50 o C, 3.5% csc, terminal ph: 1.8 (E+P+O)-Stage 60 min, 90 o C, 10% csc, 0.4% H 2 O 2, initial O 2 :35 psig 15 min; then vent 12 psig/5 min, 3.2 %NaOH D 1 -Stage 180 min, 75 o C, 10% csc, 1.0% ClO 2, terminal ph 3 E-Stage 60 min, 75 o C, 10% csc, 0.5% NaOH, terminal ph 12 D 1 -Stage 180 min, 75 o C, 10% csc, 0.2% ClO 2, terminal ph 3 Final TAPPI Brightness Values ~ 88
Bleaching Results D(E+P+O)DED TAPPI Brightness Properties Conventional ITC Mature 87.8 88.1 Thinning 87.8 88.9 60% Thin/40% Mature 88.4 88.3 40% Thin/60% Mature 88.3 80% Thin/20% Mature 88.4
Bleaching Results Pulp Viscosity Properties (mpa.s) Conventional D(EPO)DED ITC D(EPO)DED Mature 18.7 33.0 Thinning 23.0 21.3 60% Thin/40% Mature 22.1 24.7 40% Thin/60% Mature 21.6 80% Thin/20% Mature 23.1 Physical Strength Properties Evaluated After 0, 2000, and 4000 revs PFI refining
Bleaching Results D(E+P+O)DED Fiber Properties: Fiber Length 4.50 4.00 3.50 3.00 2.50 2.00 1.50 1.00 0.50 FQA Fiber Length/mm ITC Pulps 0.00 Weight-Weighted Length-Weighted 100% Thinning 100% Mature 80% Thinning/20% Mature 60% Thinning/40% Mature 40% Thinning/60% Mature 100% Thinning-ITC Cooks 100% Mature-ITC Cooks Blend of Mature:Thinning-ITC Cooks
Bleaching Results D(E+P+O)DED Fiber Properties: Tensile Index 100 100% T 100% M 60% T 100% T 100% M 60% T 90 80 70 60 50 40 Tensile Index 30 20 ITC Pulps 10 0 100% Thinning 1. 0 revs. 2. 2,000revs. 3. 4,000revs. 100%-Mature 4. 0 revs. 5. 2,000revs. 6. 4,000revs. 80% Thinning/20% Mature 7. 0 revs. 8. 2,000revs. 9. 4,000revs. 60% Thinning/40% Mature 10. 0 revs. 11. 2,000revs. 12. 4,000revs. 40% Thinning/60% Mature 13. 0 revs. 14. 2,000revs. 15. 4,000revs. 100% Thinning-ITC 16. 0 revs. 17. 2,000revs. 18. 4,000revs. 100% Mature-ITC 16. 0 revs. 17. 2,000revs. 18. 4,000revs. 60% Thin/40% Mature ITC 19. 0 revs. 20. 2,000revs. 21. 4,000revs.
Optimizing the Bleaching of Georgia s SW Thinning Wood Resource: Results D(E+P+O)DED Fiber Properties: Burst Index 8 100% T 100% M 80% T 60% T 40%T 100% T 100% M 60% T 7 6 5 4 Burst Index 3 2 1 ITC Pulps 0 100% Thinning 1. 0 revs. 2. 2,000revs. 3. 4,000revs. 100%-Mature 4. 0 revs. 5. 2,000revs. 6. 4,000revs. 80% Thinning/20% Mature 7. 0 revs. 8. 2,000revs. 9. 4,000revs. 60% Thinning/40% Mature 10. 0 revs. 11. 2,000revs. 12. 4,000revs. 40% Thinning/60% Mature 13. 0 revs. 14. 2,000revs. 15. 4,000revs. 100% Thinning-ITC 16. 0 revs. 17. 2,000revs. 18. 4,000revs. 100% Mature-ITC 16. 0 revs. 17. 2,000revs. 18. 4,000revs. 60% Thin/40% Mature ITC 19. 0 revs. 20. 2,000revs. 21. 4,000revs.
Optimizing the Bleaching of Georgia s SW Thinning Wood Resource: Results D(E+P+O)DED Fiber Properties: Tear Index 25 100% T 100% M 100% T 100% M 60% T 20 15 Tear Index 10 5 ITC Pulps 0 100% Thinning 1. 0 revs. 2. 2,000revs. 3. 4,000revs. 100%-Mature 4. 0 revs. 5. 2,000revs. 6. 4,000revs. 80% Thinning/20% Mature 7. 0 revs. 8. 2,000revs. 9. 4,000revs. 60% Thinning/40% Mature 10. 0 revs. 11. 2,000revs. 12. 4,000revs. 40% Thinning/60% Mature 13. 0 revs. 14. 2,000revs. 15. 4,000revs. 100% Thinning-ITC 16. 0 revs. 17. 2,000revs. 18. 4,000revs. 100% Mature-ITC 16. 0 revs. 17. 2,000revs. 18. 4,000revs. 60% Thin/40% Mature ITC 19. 0 revs. 20. 2,000revs. 21. 4,000revs.
Optimizing the Bleaching of Georgia s SW Thinning Wood Resource: Results D(E+P+O)DED Fiber Properties: Dry Zero Span 180 100% T 100% M 100% T 100% M 60% T 160 140 120 100 80 Dry Zero Span 60 40 20 ITC Pulps 0 100% Thinning 1. 0 revs. 2. 2,000revs. 3. 4,000revs. 100%-Mature 4. 0 revs. 5. 2,000revs. 6. 4,000revs. 80% Thinning/20% Mature 7. 0 revs. 8. 2,000revs. 9. 4,000revs. 60% Thinning/40% Mature 10. 0 revs. 11. 2,000revs. 12. 4,000revs. 40% Thinning/60% Mature 13. 0 revs. 14. 2,000revs. 15. 4,000revs. 100% Thinning-ITC 16. 0 revs. 17. 2,000revs. 18. 4,000revs. 100% Mature-ITC 16. 0 revs. 17. 2,000revs. 18. 4,000revs. 60% Thin/40% Mature ITC 19. 0 revs. 20. 2,000revs. 21. 4,000revs.
Optimizing the Bleaching of Georgia s SW Thinning Wood Resource: Results D(E+P+O)DED Fiber Properties: Wet Zero Span 160 100% T 100% M 100% T 100% M 60% T 140 120 100 80 Wet Zero Span 60 40 20 ITC Pulps 0 100% Thinning 1. 0 revs. 2. 2,000revs. 3. 4,000revs. 100%-Mature 4. 0 revs. 5. 2,000revs. 6. 4,000revs. 80% Thinning/20% Mature 7. 0 revs. 8. 2,000revs. 9. 4,000revs. 60% Thinning/40% Mature 10. 0 revs. 11. 2,000revs. 12. 4,000revs. 40% Thinning/60% Mature 13. 0 revs. 14. 2,000revs. 15. 4,000revs. 100% Thinning-ITC 16. 0 revs. 17. 2,000revs. 18. 4,000revs. 100% Mature-ITC 16. 0 revs. 17. 2,000revs. 18. 4,000revs. 60% Thin/40% Mature ITC 19. 0 revs. 20. 2,000revs. 21. 4,000revs.
Bleaching Results Conclusions: Observe differences in Thin. vs. Mature wood and kraft pulp samples are maintained in fully bleached pulps Trends observed for conventional kraft pulps observed in continuous kraft Differences in tensile vs. tear less than some northern species
Bleaching Results Conclusions: Experimental results between 40:60 and 60:40 blends of Thinning and Mature are very small and would most likely not be observed in commercial practice Depending on product grade thinnings will provide distinct cost saving with little impact on product performance
Evaluation of ECF Bleached SW Kraft Pulps From Mature and Thinning Softwood Resources Acknowledgements GA TIP3 Mill Personnel From Georgia Pacific International Paper Weyerhaeuser Rayonier