A Comparison of the kraft pulp properties of P.elliottiiand theP. elliottiixP. caribaeavar.hondurensishybrid grown in Queensland, Australia
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SYNOPSIS The interspecific hybrid between P. elliottii var. elliottii and P. caribaea var. hondurensis has recently been accepted for planting operationally as an alternative to P. elliottii by Sappi in South Africa. Some concerns have been expressed as to the suitability of the hybrid for the production of pulpwood; these stein from the observed inferiority of P. caribaea var. hondurensis, one of tile parents of this hybrid, as a source of pulpwood in South Africa. As part of a collaborative project with the Queensland Forestry Research Institute (QFRI) in Australia, who felled and supplied chips from 4 individual trees of a suitable age of each of 4 families of each taxon. The kraft pulp yield and pulp properties of P. elliottii var. elliottii and the P. elliottii x P. caribaea var. hondurensis hybrid were compared using laboratory scale pulping. Keywords: P. elliottii var elliottiiP. caribaea var. hondurensis hybrid kraft pulping laboratory scale pulping pulp yield wood density kappa burst tearAbstract BACKGROUND: Increasing the yield of the wood pulping process allows the reduction of specific wood costs. Process modifications with a great impact on pulp yield are the profiling of chemical charges and addition of anthraquinone (AQ). The aim of the present work is to investigate the influence of effective alkali (EA) profiling and addition of anthraquinone on E. globulus kraft pulping performance. The impact of such process modifications on the ECF bleaching process and on the papermaking properties of the resulting bleached pulps is also evaluated. RESULTS: An EA profiling cook may lead to a pulp yield gain, which is more significant as the total EA charge used in the kraft cook increases. AQ addition to kraft pulping leads to a significant yield increase. The ClO 2 charge required to fully bleach the pulps is lower for EA profiling and higher for kraft + AQ unbleached pulps. Bleached AQ pulp presents a high beatability due to high pulp xylan retention. CONCLUSION: A low total EA charge is the key parameter for high polysaccharide retention on pulp. AQ addition constitutes a feasible strategy to increase pulp yield. Bleaching performance and papermaking properties of pulps produced with the three different methods may be affected by the kraft pulping modifications. Copyright © 2008 Society of Chemical Industry
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Four Modified kraft (extended delignification) pulpings of plantation eucalyptus wood were carried out in laboratory. The results demonstrate that modified kraft pulping has higher pulping selectivity than conventional kraft pulping. Modified kraft pulping can produce very low Kappa number pulp with good pulp strength. Compared with the conventional kraft pulp, the Kappa number of modified kraft pulp of eucalyptus wood is 5～6 units lower, but its viscosity is more than 2.8 mPa·s higher. Modified kraft pulp has higher yield and lower rejects than its corresponding conventional kraft pulp. However, due to the slow reaction, modified kraft pulping needs greater H_factor value than conventional kraft pulping to achieve a given Kappa number.
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Paper sheets from Iranian olive tree produced by soda, sulphite and kraft pulping.Then the influence of pulp beating on properties of paper sheets was studied. Kraft pulp exhibited the highest holocellulose/yield -cellulose/yield ratios and the sulphite pulp the soda pulp the highest lignin/yield ratio. Paper sheets from kraft with the breaking length 5851 m, stretch 4.61%, Burst index 4.48 KN/g and tear index 2.03 mNm /g, exhibited the 2 highest resistance. Sulphite pulp showed the highest brightness (41%). The brightness difference between Kraft and soda pulp was not significant. Soda pulp required more intensive beating than did kraft or sulphite pulps; in fact, the PFI beater had be operated at about 50% higher number of beating revolutions to obtain soda pulp with 80-85° SR.
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Kraft pulping of bamboo under ultrasonic treatment was studied and compared with traditional kraft pulping.The obtained optimum process conditions for kraft pulping of bamboo under ultrasonic treatment was Na2O dosage 17.5 %,cooking time 120 min,and ultrasound initiating at the last 30 min of cooking.Compared with traditional kraft pulping,the dosage of Na2O decreased by 12.5 %,the cooking time shorted by 20 %,and the yield increased by 11.12 %.The properties of pulp obtained under ultrasonic treatment were close to that of pulp obtained by traditional kraft pulping.
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The authors explored the possibility of using persimmon byproducts as raw materials for obtaining kraft pulps. Various unbleached and bleached kraft pulps via pulping and bleaching processes were prepared. Then, their characteristics were determined and compared with those of commercial kraft pulps. For the highest screened yield of persimmon byproduct unbleached kraft pulps, the optimal pulping conditions were a liquid ratio of 5:1, an active alkali concentration of 25%, a sulfidity of 30%, and a cooking time of 3 h. Furthermore, the authors obtained persimmon byproduct bleached kraft pulps (PB-BKPs) with an ISO brightness of 73% via three-stage bleaching using 3% ClO2, 1.5% NaOH, and 3.5% ClO2. Moreover, PB-BKP prepared under optimal pulping and bleaching conditions had physical characteristics similar to those of commercial mixed-hardwood bleached kraft pulp, but with relatively low ISO brightness. Therefore, as raw materials, persimmon byproducts can be used for manufacturing a bleached kraft pulp.
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Kraft pulping process is the most dominant process used in paper industry. Extending delignification to a low kappa number is possible with the use of anthraquinone (AQ). The additions of AQ (0.1 per cent) results in a substantial increase in pulp yield and strength properties along with substantial decrease in kappa number. The present study deals with the kraft and kraft AQ pulping of Populus deltoides at various alkali doses, sulphidity and AQ doses. It has been found that anthraquinone (AQ) has a beneficial effect on both pulp yield and strength properties. Further kraft and kraft-AQ pulps were bleached with various conventional and nonconventional bleaching sequences including CEHH, OCEHED, OCEDED, and OCEDED to produce bleached pulp with ultra high brightness levels.
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A multistage continuous kraft pulping process that provides a more selective delignification than conventional kraft cooking is in commercial operation at a mill in Finland. This improved selectivity is used to lower the pulp's kappa number, which has contributed to reductions in the consumption of bleaching chemicals, to reductions in the effluent load of the bleach plant, and to an increase in the bleach plant's production capacity. When compared at the same kappa number, the modified pulp has a high viscosity, better strength, and consumes less bleaching chemicals than a conventional kraft pulp. Operating experiences, consumption data, and pulp-quality data for hardwood and softwood kraft pulps are reported. 6 references.
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