,,/ THE PROPERTIES OF PULPS BLEACHED IN. LOW-CHLORINE AND NON-CHLORINE COMPOUNDS BLEACHING SEQUENCES by

Transcription

1 ,,/ THE PROPERTIES OF PULPS BLEACHED IN LOW-CHLORINE AND NON-CHLORINE COMPOUNDS BLEACHING SEQUENCES by Norman Liebsrgott SPECIAL CONSULTANT TO DUPONT CANADA INC.

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4 SUMMARY OF H AND/OR D STAGES IN NORTH AM WICAN BLEACH PLANTS Total 159 CEW, CEHH, CEHP CEHD, ~ CEDH, -_ CEHBED, CHDED CEHED, CECHED CEDED, ODED, O(DC)ED 21% 28% 2% 31%

5 PRODUCTION OF PULPS USA PULP MILLION TONS/YEAR Bleached Sulphite Bleached Kraft 8i Soda 1.3 _ out of 44.1

6 PRODUCTION OF PULPS COUNTRY CHEMICAL $6 OF BLEiACHED PULP WORLD % MILLION CAPACITY TONS USA CANADA $

7 WOOD SPECIES Softwoods Pines Spruce Balsam Fir Douglas Fir Hemlock Cedar Larch Hardwoods Aspen Birch Maple Beech Oak Gums

8 TYPICAL YIELDS OF KRAFP PULPS TOTAL YIELD, % SPRUCE PINES 45 = 48 W. HEMLOCK FIR 4% - 46 at 3 kappa POPLAR we BIRCH MAPLE = 52 a% 17 kappa

9 PHYSICAL & OPTICAL PROPERTIES OF KRAFT PULPS DIFFERENT PULP GRADES DIFFERENT WOOD SPECIES LIMITS TO STRENGTH

10 TYPICAL PULP STRENGTH CHARACTERISTICS Acid Bi- High Yield Alkaline Kraft Sulphite Sulphite Sulphite SulQhae Burst Index ,O - 1. kpa.m2/g Tear Index * ,o mn.m2/g Tensile 7,5-1,5-3,5 - I1,QOQ - 11, - meters $,5Q 1 9,5 6,5 72,8 13, all at freeness 388 CSF

11 Why are pulps bleached?

12 THE PURPOSE OF BLEACHING PULP To make the pulp whiter or brighter To remove lignin, resins, metal ions, etc. To alter pulp properties To make pulp suitable for desired end use To do the least mechanical damage to the fibres To inhibit the fsrmatin of carbonyl groups To bleach at reasonable cost

13 WHAT AFFECTS THE BLEACHING PROCESS? Chemical Pulp Residual lignin (317%) must be removed Bleaching is delfgnification followed by oxidation; brightness ranges from 8 to 9%

14 New bleaching processes are being developed because of challenges to protect the environment conserve energy a conserve raw material decrease costs

15 What is the best bleaching sequence?

16 The choice of a bleaching sequence depends ora Wood or non-wood species Cooking Desired bleached pulp quality chemical physical Qptkd

17 e Effluent quality no-detect dioxins or furans no low or no AOX/chloroform low COD, BOD, colour Availability of primary, secondary, tertiary treatments

18 I. I. Availability extra capacity in recovery boiler What is the present bleaching sequence? What equipment can still be used? How much new capital funds are available?

19 METHOOS TO DECREASE CHLORINE USAGE Extended detlgnification: MCC or ROH Oxygen pretreatment:, EO, EOP Enzyme pretreatment Low-chlorine bleaching, low Kappa "4w Factor e Slow and multi-stage addition of ch)orin+ - High CIOz substitution 5 to 1% Chlorine and chlorine dioxide additiorr strategy Oxygen pretreatment + high CIOz substitution Extended dellgnification + oxygen Pretreatment + high CIOa substitution e Combination of the above

20 Lignin Removal Before Bleaching * Extended Delignification in pulping Oxygen Delignification:, (EO), (EOP) Enzyme Treatment of Brownstock

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22 METHODS TO DECREASE CHLORINE USAGE Extended delignification: MCC or RWA * Oxygen pretreatment:, EO, EOP e Enzyme pretreatment

23 a I= 3 T, 3 x) 3 b 1 m d e9 (v T- 1 I CD v) d I I I I O

24 Lignin Removal Before Bleaching Extended Delignification in pulping Oxwen Delignification:, (EO), (EOP) Enzyme Treatment of Brownstock

25 7 r I I 6 -\ Spruce-Fir-Pine Kraft Kappa NO, Unbl. 3,Q 5 4 m - - m v 16,6 3 2 D \\ 1 I I I I I I I I Percent CIO, substitution in C-stage

26 Total CI-phenolics in CEO effluents, g/metric ton pulp (OD basis) N P 6, / ;o" a - E d 8

27 LOW CHLORINE BLEACHING Low Kappa Number Factor (ACM) Multistage Addition of Chlorine High Chlorine Dioxide Substitution: 5 to 1% Enzyme Pretreatment

28 1 ano Dioxin found mil9 Active chlorine multiple m

29 / TO ACCOMPLISH LOW CHLORINE BLEACHING It is necessary to improve the efficiency of the extraction stage by: raising the temperature. e reinforcing the Eo stage with Peroxide (EoP). adding MgS4 to the Peroxide Solution.

30 EFFECT OF MgS4 Softwood Kraft Pulp Kappa No. 3.1: Viscosity 3.4 mpa.s E Stages NaOH added, % H22 added, %.45 MgS4 added, % -me.5 End ph Kappa No Brightness, % Viscosity, mpa.s

31 Varying the Act. Chlorine Multiple in Tn Kappa No ViSCOSitY, 41.1 mh.s Properties after "C" Eo Kappa No, AOX, kg/adtbp m

32 clb cz Ip 'CI 8

33 EFFECT OF MgS4 Hardwood Kraft Pulp kppa No. 17.2: Viscosity 23.8s E Stages NaOH added, H22 added, % MgSO4 added, % ".25 End ph Kappa No Brightness, % Viscosity, mpa.s

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36 XYLANASE TREATMENT In chlorine compound In non-chlorine compound bleaching.

37 XYLANASE TREATMENT Questions outstanding: e cost a Purity Loss of pulp yield? (P Reliable domestic supply.

38 ENZYME PRETREATMENT QF KRAFT PULP Unbleached Kappa No., 32.; Viscosity, 3.7 mpa.s Enzyme Stage No Yes _p1 PH _o Xylanase Charge --.D Time, hrs. Temperature, OC.-.I, Kappa No. 32. Viscosity, m Pa. s units kg/pulp

39 ENZYME PRETREATMENT OF KRAFT PULP Unbleached Kappa No., 32.; Viscosity, 3.7 mpa.s Enzyme Stage No Yes '*C" and Eo Stage Effluent Properties, kg/t AOX 2.2 CQlQUt' 135 BOD 15 coo I1 62

40 ENZYME PRETREATMENT OF KRAFT PULP Unbleached Kappa No., 32.; Viscosity, 3.7 mpa.s Enzyme Stage Kappa No. NO 32. Yes 31.3 D7C3 Stage Active CI,, kg/tp

41 "i 3 r I- 22 EFFECT OF X PRE-TREATMENT Pretreatment Kappa factor none 2 o yes 16 yes A yes" 2 * yes* I I I I I I 1 I I I I I I J Breaking length, km

42 Brightness 9% a, 12 U c" - a I- 1 a.d &D,,(EQ~)DEO I) V / / A boo( Eop)DED.22 XD,W(Eop)DED.16 PP I I I 1 // Breaking Lengt I I

43 Using oxygen and peroxide (and sometime a little chlorine dioxide) to bleach chemical pulp

44 FOR LOW CHLORINE BLEACHING To control shives and dirt: e D, stage must have a residual. a Terminal ph should be

45 OPTIMIZATION OF VARIOUS BLEACHING STAGES (contd) c 1 c A. Lodgepole Pine-Spruce Kraft Pulp, C$,D Treated. 74 t w m M p n B. Black Spruce Softwood Pulp, (DC)EoD Treated m c,,,,,,,, -pn -m C. Eastern nixed hardwood Kraft Pulp, C$,IID Treated Figure 1. The relationship between the pe (measured at the end of the chlorine dioxide stage) on the properties of pulps. C12 Bleaching Conditions: consistency, 1%; temperature, 6 to 7.C; retention time, 18 minutes; chlorine dioxide charge,.9 to.7% C12 on pulp.

46 e D(EP)PDP.25% MgSO, in B.5% MgS4 in P 2 15 IO 5-2 m I m I a I * I * I m Breaking :length, km 14

47 BLEACHING TECHNOLOGY: e Near future: stages in sequence will include oxygen peroxide chlorine dioxide ozone

48 Alternatives to Chlorine Compounds Oxygen Peroxide Ozone Peracetic Acid H ydrosul phite Chelating Agents Thiourea dioxide

49 Peroxide Bleaching of Kraft Pulp Kappa No. before QP a QP OQP A EopQP

50 e. && QCP. w w 4a P, 88 E O

51 Peroxide Bleaching of Sulphite Pulp I 9 c I=' m Kappa No. before QP

52 12 Effect of Cooking Kappa No. and, Delignification on Tear Index at 12 km Breaking Length cv E i E X a U C d / I I I I I C Kappa Nom

53 ~ Unbleached 2 Kappa Kappa No. No QOQPP Brightness, Viscosity, % mpa.s AT Breakin 8, km rear Index mn.m*/g

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55 ~ ~~ ~~ ~ Comparing OP and OQP Kraft- Pulp; kappa no. 13.6; Brightness, 32.3 Q-stage P-stage *2O,, % added no % cons a 4 Temp, OC Time, hrs IS Bright., % Vise., mpa.s -- =I Q-stage:.6% EDTA; ph 6.6; 3 min; 9 C P-stage: NaOH to ph 11.7:.5% MgSO,;.2% DTPA

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57 4 1 cv f E 25 x" ) 2 IOI C =- 15 z g 1 QEopQP * F.Blchd 5 I I I I I I I I I I a Breaking length, km

58 9. [XED HARDWO OD KRAFT PULP A CDEQDED QOQP e QEopQPP I 1 I I I Breaking Len

59 STRENGTH PROPERTIES OF PULPS Kraft PUlP White Spruce/ CDEoDED Lodgepole Pine DEopPDP QfipQPDP QEopQPDP Spruce/Pine DlOOEopDE D Q~PQP Q(P)QP Q(bp)QPQ P Mixed Hardwoods CDEoDED QOQP QbPQPP *ml CSF Bulk Gm3/g 5* Burst kpa.m2/g Tear M"2/g km Breaking Length

60 Burst kpa a m2/g 3 9 $ llt

61 Using Ozone in a Sequence Sequence -2-E-P -( PZ)-E-P -( PZE)-P Brightness, %

62 13 12 Treatment i E 11 1 I AO(2PE)PY TEAR VS. ViSCOSlTV Tear Index at a Breaking Length of 13 km 1 I I I Viscosity, mpa.s

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64 .I, O(ZE)QP Bleaching of Alcell and Kraft Hardwood Pulps 9' 8 a o+!/ I) P / Pulp Kappa No. H Kraft 18. Alcell 32. I I II I I 1 I IO g length, km

65 z a> 16 c= L CI t3 fl Pulp Bleaching of Spruce Kraft and ASAM Pulps Yield, % Kappa No. H *ASAM / II I I I I m I I I I II a Tensile strength, km

66 p" Q) I+-- a en I e.a c

67 . O(PZE)QP Bleaching of Kraft and Soda-AQ Spruce Pulps 4 1 Pulp Yield, % Kappa No. Kraft I I I I I I I Breaking length, km

68 IO Pulp ZE)PY Bleaching of Kraft and Soda-AQ Mixed Hardwood Pulps Yield, % Kappa No. Breaking length, km

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71 OXYGEN-PEROXIDE BLEACHING TRIALS DATE PULP MILL BRIGHTNESS, TOTAL LWC LOCATION % PRODUCTION, PAPER tonnes QUALITY 199 Aspa Bruk, 742 Sweden 9, poor strength 1991 Metsa-Serla, 75 3,5 satisfactory Kaskinen, (enzyme treated strength Finland after oxygen) 1991 Aspa Bruk, TPD satisfactory Sweden strength?

72 BLEACHING TECHNOLOGY: Major thrust: cutting back on chlorine usage Chlorine compound-free - oxygen-peroxide combination maximum brightness around 8 - stringent control of each stage good quality pulp at low kappa number entering bleach p!ant

73 * m P 3 P m C B I v) CI 3 W L P I rc c 9- b r G.E...

74 OXYGEN-PER XIDE BLEA HING TRIALS DATE PULP MILL BRIGHTNESS, TOTAL LWC LOCATION % PRODUCTION, PAPER tonnes QUALITY 199 Aspa Bruk, 7-92 Sweden 9, poor streflgth a

75 OXYGEN-PEROXIDE BLEACHING TRIALS DATE PULP MILL BRIGHTNESS, TOTAL LWC LOCATION % PRODUCTION, PAPER tonnes QUALITY 199 Aspa Bruk, 7-72 Sweden 9, poor strength 1991 Metsa-Serla, 75 3,5 satisfactory Kaskinen, (enzyme treated strength Finland after oxygen)

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