The compromise between reaching pulp target brightness and guaranteeing a high-quality bleached pulp is often difficult to manage because of the nature of the last chromophores present. This study reports the performance of either hydrogen peroxide or chlorine dioxide in a final bleaching stage applied to three eucalypt D0EOPD1 kraft pulps to reach a target ISO brightness of 90±0.5%. The D1 pulps had ISO brightness values of 84.7%, 86.9%, and 88.7% (pulps A, B, and C, respectively). The experimental results revealed that while chlorine dioxide charge was linearly correlated with D1 brightness, a much higher hydrogen peroxide charge was needed to bleach pulp A compared with pulps B and C. All P pulps had lower brightness reversion and better beatability than D2 pulps. In addition, we observed better physical and optical papermaking properties in P pulps (except for tear index for pulp A), although these pulps exhibited lower intrinsic viscosity. Therefore, the best choice for completing that particular ECF sequence is to push chlorine-dioxide bleaching action in D1 until at least 87% ISO brightness is reached, with the purpose of degrading phenolic units as much as possible, and then to advance with peroxide to boost brightness at the cost of quinone destruction.
{"title":"Performance of a final hydrogen peroxide stage in the ECF bleaching of Eucalypt D0EOPD1 kraft pulps","authors":"M. Carvalho, N. M. V. Carvalho, P. Loureiro","doi":"10.32964/tj7.8.8","DOIUrl":"https://doi.org/10.32964/tj7.8.8","url":null,"abstract":"The compromise between reaching pulp target brightness and guaranteeing a high-quality bleached pulp is often difficult to manage because of the nature of the last chromophores present. This study reports the performance of either hydrogen peroxide or chlorine dioxide in a final bleaching stage applied to three eucalypt D0EOPD1 kraft pulps to reach a target ISO brightness of 90±0.5%. The D1 pulps had ISO brightness values of 84.7%, 86.9%, and 88.7% (pulps A, B, and C, respectively). The experimental results revealed that while chlorine dioxide charge was linearly correlated with D1 brightness, a much higher hydrogen peroxide charge was needed to bleach pulp A compared with pulps B and C. All P pulps had lower brightness reversion and better beatability than D2 pulps. In addition, we observed better physical and optical papermaking properties in P pulps (except for tear index for pulp A), although these pulps exhibited lower intrinsic viscosity. Therefore, the best choice for completing that particular ECF sequence is to push chlorine-dioxide bleaching action in D1 until at least 87% ISO brightness is reached, with the purpose of degrading phenolic units as much as possible, and then to advance with peroxide to boost brightness at the cost of quinone destruction.","PeriodicalId":179766,"journal":{"name":"August 2008","volume":"81 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114568772","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We investigated the influence of refining conditions (refiner tackle type and specific edge load) on bulk softness, absorbency, tensile strength, and wet tensile strength of bleached pulp. Commercial elemental chlorine free (ECF) and totally chlorine free (TCF) bleached sulfite and kraft spruce, birch, and eucalypt pulps were used in this investigation. We found that refiner tackle type and specific edge load had a significant influence on the evaluated properties. Higher specific edge load when using a universal tackle increases softness and absorbency of hard-wood kraft pulps. The highest tensile index of bleached hardwood kraft and spruce sulfite pulps was achieved by fibrillation refining at low specific edge load (under 0.70 J/m). The wet tensile strength index of the tested pulps beaten to 30°SR increased 3-4 times. Pulp refining increases wet tensile index and reduces water absorbency of paper. Hardwood kraft pulps are suitable for production of tissue paper with high softness and absorbency. Spruce sulfite pulps are suitable to achieve high bulk softness and low tissue paper absorbency. Birch kraft pulp is a good choice if a higher tensile strength is required in addition to softness and absorbency. To manufacture tissue papers with deep embossing, softwood kraft pulp is required because of its high strength properties.
{"title":"Influence of pulp refining on tissue paper properties","authors":"J. Gigac, M. Fišerová","doi":"10.32964/tj7.8.27","DOIUrl":"https://doi.org/10.32964/tj7.8.27","url":null,"abstract":"We investigated the influence of refining conditions (refiner tackle type and specific edge load) on bulk softness, absorbency, tensile strength, and wet tensile strength of bleached pulp. Commercial elemental chlorine free (ECF) and totally chlorine free (TCF) bleached sulfite and kraft spruce, birch, and eucalypt pulps were used in this investigation. We found that refiner tackle type and specific edge load had a significant influence on the evaluated properties. Higher specific edge load when using a universal tackle increases softness and absorbency of hard-wood kraft pulps. The highest tensile index of bleached hardwood kraft and spruce sulfite pulps was achieved by fibrillation refining at low specific edge load (under 0.70 J/m). The wet tensile strength index of the tested pulps beaten to 30°SR increased 3-4 times. Pulp refining increases wet tensile index and reduces water absorbency of paper. Hardwood kraft pulps are suitable for production of tissue paper with high softness and absorbency. Spruce sulfite pulps are suitable to achieve high bulk softness and low tissue paper absorbency. Birch kraft pulp is a good choice if a higher tensile strength is required in addition to softness and absorbency. To manufacture tissue papers with deep embossing, softwood kraft pulp is required because of its high strength properties.","PeriodicalId":179766,"journal":{"name":"August 2008","volume":"10 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128355765","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Lipase hydrolysis of ester linkages on the surface of hydrophobic fines was suggested in a previous paper as a new method to promote hydration of the fines and to prevent the unwanted loss of these fines during froth flotation. Lipase was added before the secondary flotation stage of old newspapers (ONP) such that concentrated hydrophobic fine components were subjected to selective lipase hydrolysis. As a result, secondary flotation rejects were reduced, while the brightness and the effective residual ink concentration (ERIC) of secondary flotation accepts were maintained at the same level as the nontreated case. The application of lipase in secondary stage flotation results in fewer rejects from the low alkaline or neutral deinking of ONP by the enhancement of flotation deink-ing selectivity.
{"title":"Application of lipase to reduce ONP flotation rejects. Part 2. Reduction of flotation rejects","authors":"Jeong-yong Ryu, B. Song, J. Song","doi":"10.32964/tj7.8.3","DOIUrl":"https://doi.org/10.32964/tj7.8.3","url":null,"abstract":"Lipase hydrolysis of ester linkages on the surface of hydrophobic fines was suggested in a previous paper as a new method to promote hydration of the fines and to prevent the unwanted loss of these fines during froth flotation. Lipase was added before the secondary flotation stage of old newspapers (ONP) such that concentrated hydrophobic fine components were subjected to selective lipase hydrolysis. As a result, secondary flotation rejects were reduced, while the brightness and the effective residual ink concentration (ERIC) of secondary flotation accepts were maintained at the same level as the nontreated case. The application of lipase in secondary stage flotation results in fewer rejects from the low alkaline or neutral deinking of ONP by the enhancement of flotation deink-ing selectivity.","PeriodicalId":179766,"journal":{"name":"August 2008","volume":"7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127939242","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The rate of gravity drainage from a papermaking stock suspension is highly dependent on the initial consistency of the stock, and on the presence of cellulosic fines. In this study, we fitted the results of testing to a model based on different linear contributions to drainage resistance from fibers and each type of fines. Deviations from the model at relatively high consistency were tentatively attributed to flocculation phenomena. Substantially higher rates of dewatering were achieved by selectively treating the fines, the fibers, or the combined furnish with cationic polyelectrolytes. Results were consistent with several mechanisms, which might act in parallel during ordinary papermaking. Attachment of cellulosic fines to fiber surfaces can prevent those fines from migrating to choke points within a wet web. Agglomeration of fines to each other can reduce their effective surface area. Flocculation of the fibers can make the fiber mat less uniform, thus providing larger channels for water to flow from the mat.
{"title":"Water release from fractionated stock suspension. Part 2. Effects of consistency, flocculants, shear, and order of mixing","authors":"M. Hubbe, J. Heitmann, Cedric A. Cole","doi":"10.32964/tj7.8.14","DOIUrl":"https://doi.org/10.32964/tj7.8.14","url":null,"abstract":"The rate of gravity drainage from a papermaking stock suspension is highly dependent on the initial consistency of the stock, and on the presence of cellulosic fines. In this study, we fitted the results of testing to a model based on different linear contributions to drainage resistance from fibers and each type of fines. Deviations from the model at relatively high consistency were tentatively attributed to flocculation phenomena. Substantially higher rates of dewatering were achieved by selectively treating the fines, the fibers, or the combined furnish with cationic polyelectrolytes. Results were consistent with several mechanisms, which might act in parallel during ordinary papermaking. Attachment of cellulosic fines to fiber surfaces can prevent those fines from migrating to choke points within a wet web. Agglomeration of fines to each other can reduce their effective surface area. Flocculation of the fibers can make the fiber mat less uniform, thus providing larger channels for water to flow from the mat.","PeriodicalId":179766,"journal":{"name":"August 2008","volume":"40 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114784350","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Carla A. F. Ventura, F. Garcia, P. Ferreira, M. Rasteiro
The transport between different equipment and unit operations plays an important role in pulp and paper mills because fiber suspensions differ from all other solid-liquid systems, due to the complex interactions between the different pulp and paper components. Poor understanding of the suspensions’ flow dynamics means the industrial equipment design is usually conservative and frequently oversized, thus contributing to excessive energy consumption in the plants. Our study aim was to obtain additional knowledge about the dynamic behavior of industrial pulp suspensions in order to evaluate the relative importance of the factors that influence pressure drop. To obtain mathematical correlations to quantify pressure drop for the transport of pulp suspensions, we studied four different industrial pulp suspensions (recycled pulp, eucalypt bleached kraft pulp, pine unbleached kraft pulp, and eucalypt [90%] + pine [10%] bleached kraft pulp) in a pilot rig specially designed and built for the effect.
{"title":"Flow dynamics of pulp fiber suspensions","authors":"Carla A. F. Ventura, F. Garcia, P. Ferreira, M. Rasteiro","doi":"10.32964/tj7.8.20","DOIUrl":"https://doi.org/10.32964/tj7.8.20","url":null,"abstract":"The transport between different equipment and unit operations plays an important role in pulp and paper mills because fiber suspensions differ from all other solid-liquid systems, due to the complex interactions between the different pulp and paper components. Poor understanding of the suspensions’ flow dynamics means the industrial equipment design is usually conservative and frequently oversized, thus contributing to excessive energy consumption in the plants. Our study aim was to obtain additional knowledge about the dynamic behavior of industrial pulp suspensions in order to evaluate the relative importance of the factors that influence pressure drop. To obtain mathematical correlations to quantify pressure drop for the transport of pulp suspensions, we studied four different industrial pulp suspensions (recycled pulp, eucalypt bleached kraft pulp, pine unbleached kraft pulp, and eucalypt [90%] + pine [10%] bleached kraft pulp) in a pilot rig specially designed and built for the effect.","PeriodicalId":179766,"journal":{"name":"August 2008","volume":"112 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131843241","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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