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1、49Pulpingreferstoanyprocessbywhichwood(orotherfibrousrawmaterial)isreducedtoafibrousmass.Basically,itisthemeansbywhichthebondsaresystematicallyrupturedwithinthewoodstructure.Thetaskcanbeaccomplishedmechanically,thermally,chemically,orbycombinationsofthesetreatments.Existingc
2、ommercialprocessesarebroadlyclassifiedasmechanical,chemicalorsemichemical.ThegeneralcharacteristicsoftheseprocessesaresummarizedinTable4-1.CurrentannualpulpproductionbyeachmajorprocessisshowninTable4-2.Chemicalpulpingaccountsfor70%ofNorthAmericanproduction,ofwhich95%isproduc
3、edbythedominantkraftprocess.Thetabulationshowsthatsemichemicalpulpingaccountsforonlyabout5%ofproduction;however,"high-yieldkraft"and"high-yieldsulfite"tonnagenowincludedinthetotalsforunbleachedkraftandsulfiteshouldmoreappropriatelybeincludedundersemichemical.table4-2.NorthAm
4、ericanpulpproduction1990(000000shorttons).Sources:API&CPPA.USACanadaDissolving1,293221Chemicalpulp,papergradesTotalsulfite1,5611,603Bleachedhardwoodkraft1,764Bleachedsoftwoodkraft7,006Totalbleachedkraft27,5628,770Unbleachedkraft22,1881,503Totalkraft49,75010,273Semimechanical
5、4,219514Mechanical6,45211,637Total63,27525,234AtallyofNorthAmericanforest-basedpulpmillssituatedintheprincipalpulp-producingstatesandprovinces(Table4-3)helpstoprovideageographicalperspective.Itisofinteresttonotethatmostofthesulfitemillsarelocatedintraditionalpulp-producingar
6、eas(e.g.,Washington.Wisconsin.Ontario,Quebec),whilemore-recentlyexploitedareas(e.g.,Alabama.Georgia,Louisiana.BritishColumbia)arerelyingprincipallyonthekraftprocessforchemicalpulping.table4-3.Geographicaldistributionofpulpmills,1990(Lockwood'sDirectory).,Semi-Mech-.KraftSulf
7、itechemanicalTotalUnitedStatesAlabama14-2420Georgia12-125Louisiana10-4317Maine71-1018Oregon7-31117Washington763723Wisconsin4611122CanadaBrit.Columbia181-1534Ontario9421530Quebec10824161Acompletelistingofpulpmillswouldalsoincludethecategory,"secondaryfiber".Underthisheadingar
8、etheoperationsthatrecoverusablepulpfiberfromvariouswastepapersources.Thisfi
