O processo AD(EO)D – um novo conceito.

In this study, cooking of the wood had been investigated until kappa numbers 17 and 14 for a process kinetically modified, elimination of oxygen delignification from the fiber line, and application of AD(EO)D and AD(PO)D techniques for pulp of kappa 17 and AD(EO)D and DHT(EPO)DP for pulp of kappa 14 for the bleaching at 90% ISO. As references, cookings had been carried out until kappa number 17 and 14, oxygen delignification in simple stage and conventional bleaching with sequences A/D(EO)D, A/D(EPO)D, A/D(EO)DP and A/D(EPO)DP for the kappa number 17 pulp and oxygen delignification in simple stage and conventional bleaching sequence DHT(EPO)DP for pulp of kappa 14. For the pulp of kappa 17, one concluded that processes AD(EO)D and AD(PO)D produced pulp of brightness 90% ISO with good viscosity and brightness stability, using TAC´s (totally active chloro) relatively low, and it’s not necessary the oxygen delignification. Amongst these two processes, the first one revealed to be more attractive to reach the level of 90% ISO brightness. However, comparatively to the reference processes, with oxygen delignification, for example O-A/D(EPO)DP, process AD(EO)D results in increase of the operational cost of the order of US$7-8/odt, including wood and reagents. For the kappa number 14 pulp, process AD(EO)D also revealed to be attractive, but the sequence DHT(EPO)DP was the one that used lower TAC`s; however, when compared with the reference (O-DHT(EPO)DP), it resulted in an increase of operational cost of the order of US$5/odt. Therefore, it can be concluded that the alternative process, without the deslignification with oxygen, is viable only for pulps of lower kappa number.Nesse estudo, investigaram-se cozimentos da madeira até números kappa 17 e 14 por um processo cineticamente modificado, eliminação da deslignificação com oxigênio da linha de fibras, e aplicação das técnicas AD(EO)D e AD(PO)D para polpa de kappa 17 e AD(EO)D e DHT(EPO)DP para polpa de kappa 14 para o branqueamento até 90% ISO. Como referências, foram realizados cozimentos até números kappa 17 e 14, deslignificação com oxigênio em simples estágio e branqueamento convencional pelas seqüências A/D(EO)D, A/D(EPO)D, A/D(EO)DP e A/D(EPO)DP para a polpa de kappa 17 e deslignificação com oxigênio em simples estágio e branqueamento convencional pela seqüência DHT(EPO)DP para polpa de kappa 14.  Para a polpa de kappa 17, concluiu-se que os processos AD(EO)D e AD(PO)D produzem polpa de alvura 90% ISO com boa viscosidade e estabilidade de alvura, utilizando TAC´s (Cloro Ativo Total) relativamente baixos, e dispensam completamente a deslignificação com oxigênio. Dentre esses dois processos, o primeiro se mostrou mais atrativo para atingir o nível de alvura de 90% ISO. Porém, comparativamente aos processos de referência, contendo a deslignificação com oxigênio, ex. O-A/D(EPO)DP, o processo AD(EO)D resulta em aumento do custo operacional da ordem de US$7-8/tas, inclusos madeira e reagentes. Para a polpa de número kappa 14, o processo AD(EO)D também se mostrou atrativo, sendo que a seqüência DHT(EPO)DP foi a que utilizou o menor TAC`s, porém quando comparada com a referência (O-DHT(EPO)DP) resultou num aumento de custo operacional da ordem de US$4/tas.  Portanto, pode se concluir que o processo alternativo, sem a deslignificação com oxigênio, é viável somente para polpas de números kappa mais baixos

The AD(EO)D process - a new concept

In this study, cooking of the wood had been investigated until kappa numbers 17 and 14 for a process kinetically modified, elimination of oxygen delignification from the fiber line, and application of AD(EO)D and AD(PO)D techniques for pulp of kappa 17 and AD(EO)D and DHT(EPO)DP for pulp of kappa 14 for the bleaching at 90% ISO. As references, cookings had been carried out until kappa number 17 and 14, oxygen delignification in simple stage and conventional bleaching with sequences A/D(EO)D, A/D(EPO)D, A/D(EO)DP and A/D(EPO)DP for the kappa number 17 pulp and oxygen delignification in simple stage and conventional bleaching sequence DHT(EPO)DP for pulp of kappa 14. For the pulp of kappa 17, one concluded that processes AD(EO)D and AD(PO)D produced pulp of brightness 90% ISO with good viscosity and brightness stability, using TAC\ub4s (totally active chloro) relatively low, and it\u2019s not necessary the oxygen delignification. Amongst these two processes, the first one revealed to be more attractive to reach the level of 90% ISO brightness. However, comparatively to the reference processes, with oxygen delignification, for example O-A/D(EPO)DP, process AD(EO)D results in increase of the operational cost of the order of US$7-8/odt, including wood and reagents. For the kappa number 14 pulp, process AD(EO)D also revealed to be attractive, but the sequence DHT(EPO)DP was the one that used lower TAC`s; however, when compared with the reference (O-DHT(EPO)DP), it resulted in an increase of operational cost of the order of US$5/odt. Therefore, it can be concluded that the alternative process, without the deslignification with oxygen, is viable only for pulps of lower kappa number.Nesse estudo, investigaram-se cozimentos da madeira at\ue9 n\ufameros kappa 17 e 14 por um processo cineticamente modificado, elimina\ue7\ue3o da deslignifica\ue7\ue3o com oxig\ueanio da linha de fibras, e aplica\ue7\ue3o das t\ue9cnicas AD(EO)D e AD(PO)D para polpa de kappa 17 e AD(EO)D e DHT(EPO)DP para polpa de kappa 14 para o branqueamento at\ue9 90% ISO. Como refer\ueancias, foram realizados cozimentos at\ue9 n\ufameros kappa 17 e 14, deslignifica\ue7\ue3o com oxig\ueanio em simples est\ue1gio e branqueamento convencional pelas seq\ufc\ueancias A/D(EO)D, A/D(EPO)D, A/D(EO)DP e A/D(EPO)DP para a polpa de kappa 17 e deslignifica\ue7\ue3o com oxig\ueanio em simples est\ue1gio e branqueamento convencional pela seq\ufc\ueancia DHT(EPO)DP para polpa de kappa 14. Para a polpa de kappa 17, concluiu-se que os processos AD(EO)D e AD(PO)D produzem polpa de alvura 90% ISO com boa viscosidade e estabilidade de alvura, utilizando TAC\ub4s (Cloro Ativo Total) relativamente baixos, e dispensam completamente a deslignifica\ue7\ue3o com oxig\ueanio. Dentre esses dois processos, o primeiro se mostrou mais atrativo para atingir o n\uedvel de alvura de 90% ISO. Por\ue9m, comparativamente aos processos de refer\ueancia, contendo a deslignifica\ue7\ue3o com oxig\ueanio, ex. OA/ D(EPO)DP, o processo AD(EO)D resulta em aumento do custo operacional da ordem de US7-8/tas, inclusos madeira e reagentes. Para a polpa de n\ufamero kappa 14, o processo AD(EO)D tamb\ue9m se mostrou atrativo, sendo que a seq\ufc\ueancia DHT(EPO)DP foi a que utilizou o menor TAC`s, por\ue9m quando comparada com a refer\ueancia (O-DHT(EPO)DP) resultou num aumento de custo operacional da ordem de US4/tas. Portanto, pode se concluir que o processo alternativo, sem a deslignifica\ue7\ue3o com oxig\ueanio, \ue9 vi\ue1vel somente para polpas de n\ufameros kappa mais baixos

Avaliação das propriedades físico-mecânicas de polpas produzidas por novas sequências de branqueamento.

The efficiency of oxygen delignification is very low for pulps of low number kappa and with high concentrations of hexenuronic acids, therefore the oxygen does not react with these acids, so being minimum the elimination of these during the oxygen delignification (pre-O2) in simple or double stage. In this study, the physical-mechanical properties of pulp of kappa number 17 and 14, produced with modified cooks and with the application of AD(EO)D techniques for pulp of kappa 17 and DHT(EPO)DP for pulp of kappa 14 for the bleaching up to 90% ISO, had been investigated. The main objective of this study was to evaluate the physical-mechanical properties in pulps submitted to the bleaching sequences without oxygen in the beginning of the sequence. As references, cooks had been carried until numbers kappa 17 and 14, oxygen delignification and conventional bleaching for sequences A/D(EO)D for pulp of kappa 17 and DHT(EPO)DP for pulp of kappa 14. The alternative bleaching, without pre-O2, resulted in bleached pulps with bigger integrity that of the reference, what it was confirmed by the values significantly higher of bulk, tear index, opacity and air resistance of the pulp weakly refined (for tissue papers). However, the high integrity of the fibers from pulps bleached with alternative processes lowered their conformabilities and collapsibility, with consequent reduction of tensile index of the pulp weakly refined. Therefore, with more intensive beating (for printing and writing papers), the tensile index was recovered. The high integrity of the bleaching pulps without pre-O2 makes beating difficulty. To reach the draining degree of 35°SR with the pulps proceeding from alternative processes of bleaching, it was necessary to apply 30% more energy than the reference.A eficiência da deslignificação com oxigênio (pré-O2) é muito baixa para polpas de baixo número kappa e que contêm altas concentrações de ácidos hexenurônicos, pois o oxigênio não reage com esses ácidos, sendo mínima a eliminação destes durante a deslignificação com oxigênio em simples ou duplo estágio. Neste estudo, investigaram-se as propriedades físico-mecânicas de polpas produzidas por cozimentos cineticamente modificados até número kappa 17 e 14 e branqueadas pelas técnicas AD(EO)D, para polpa de kappa 17 e DHT(EPO)DP, para polpa de kappa 14. O objetivo principal do estudo foi o de avaliar as propriedades físico-mecânicas das polpas submetidas a sequências de branqueamento sem o oxigênio, no início da sequência. Como referências, foram produzidas polpas de número kappa 17 e 14 as quais foram posteriormente deslignificadas com oxigênio e branqueadas com sequências convencionais: A/D(EO)D, para polpa de número kappa 17 e DHT(EPO)DP, para polpa de kappa 14. O branqueamento alternativo, sem a pré-O2, resultou em polpas branqueadas de maior integridade que as da referência, o que foi comprovado pelos valores significativamente mais altos de VEA (bulk), índice de rasgo, opacidade e resistência à passagem de ar (RPA) da polpa fracamente refinada (polpa para produzir papel tissue). Por outro lado, a alta integridade das fibras oriundas das polpas branqueadas por processos alternativos diminuiu suas conformabilidades e colapsabilidades, com consequente diminuição do índice de tração da polpa fracamente refinada. Porém, mediante um refino mais intenso (polpa para produzir papel de imprimir e escrever - P&W) o índice de tração foi recuperado. A alta integridade das polpas branqueadas sem a pré-O2 dificulta o seu refino. Para alcançar o grau de drenagem de 35oSR com as polpas provenientes dos processos alternativos de branqueamento, foi necessário aplicar cerca de 30% a mais de energia em relação à referência

Physical-Mechanical Properties Evaluation Of Pulps Produced With Novel Bleaching Sequences

A efici\ueancia da deslignifica\ue7\ue3o com oxig\ueanio (pr\ue9-O2) \ue9 muito baixa para polpas de baixo n\ufamero kappa e que cont\ueam altas concentra\ue7\uf5es de \ue1cidos hexenur\uf4nicos, pois o oxig\ueanio n\ue3o reage com esses \ue1cidos, sendo m\uednima a elimina\ue7\ue3o destes durante a deslignifica\ue7\ue3o com oxig\ueanio em simples ou duplo est\ue1gio. Neste estudo, investigaram-se as propriedades f\uedsico-mec\ue2nicas de polpas produzidas por cozimentos cineticamente modificados at\ue9 n\ufamero kappa 17 e 14 e branqueadas pelas t\ue9cnicas AD(EO)D, para polpa de kappa 17 e DHT(EPO)DP, para polpa de kappa 14. O objetivo principal do estudo foi o de avaliar as propriedades f\uedsico-mec\ue2nicas das polpas submetidas a sequ\ueancias de branqueamento sem o oxig\ueanio, no in\uedcio da sequ\ueancia. Como refer\ueancias, foram produzidas polpas de n\ufamero kappa 17 e 14 as quais foram posteriormente deslignificadas com oxig\ueanio e branqueadas com sequ\ueancias convencionais: A/D(EO)D, para polpa de n\ufamero kappa 17 e DHT(EPO)DP, para polpa de kappa 14. O branqueamento alternativo, sem a pr\ue9-O2, resultou em polpas branqueadas de maior integridade que as da refer\ueancia, o que foi comprovado pelos valores significativamente mais altos de VEA (bulk), \uedndice de rasgo, opacidade e resist\ueancia \ue0 passagem de ar (RPA) da polpa fracamente refinada (polpa para produzir papel tissue). Por outro lado, a alta integridade das fibras oriundas das polpas branqueadas por processos alternativos diminuiu suas conformabilidades e colapsabilidades, com consequente diminui\ue7\ue3o do \uedndice de tra\ue7\ue3o da polpa fracamente refinada. Por\ue9m, mediante um refino mais intenso (polpa para produzir papel de imprimir e escrever \u2013 P&W) o \uedndice de tra\ue7\ue3o foi recuperado. A alta integridade das polpas branqueadas sem a pr\ue9-O2 dificulta o seu refino. Para alcan\ue7ar o grau de drenagem de 35oSR com as polpas provenientes dos processos alternativos de branqueamento, foi necess\ue1rio aplicar cerca de 30% a mais de energia em rela\ue7\ue3o \ue0 refer\ueancia.The efficiency of oxygen delignification is very low for pulps of low number kappa and with high concentrations of hexenuronic acids, therefore the oxygen does not react with these acids, so being minimum the elimination of these during the oxygen delignification (pre-O2) in simple or double stage. In this study, the physical-mechanical properties of pulp of kappa number 17 and 14, produced with modified cooks and with the application of AD(EO)D techniques for pulp of kappa 17 and DHT(EPO)DP for pulp of kappa 14 for the bleaching up to 90% ISO, had been investigated. The main objective of this study was to evaluate the physical-mechanical properties in pulps submitted to the bleaching sequences without oxygen in the beginning of the sequence. As references, cooks had been carried until numbers kappa 17 and 14, oxygen delignification and conventional bleaching for sequences A/D(EO)D for pulp of kappa 17 and DHT(EPO)DP for pulp of kappa 14. The alternative bleaching, without pre-O2, resulted in bleached pulps with bigger integrity that of the reference, what it was confirmed by the values significantly higher of bulk, tear index, opacity and air resistance of the pulp weakly refined (for tissue papers). However, the high integrity of the fibers from pulps bleached with alternative processes lowered their conformabilities and collapsibility, with consequent reduction of tensile index of the pulp weakly refined. Therefore, with more intensive beating (for printing and writing papers), the tensile index was recovered. The high integrity of the bleaching pulps without pre-O2 makes beating difficulty. To reach the draining degree of 35\ub0SR with the pulps proceeding from alternative processes of bleaching, it was necessary to apply 30% more energy than the reference

Alternative methods of xylans deposition onto eucalyptus pulps

Polpas kraft de eucalipto são amplamente utilizadas para papéis de imprimir e escrever (P&W). Papéis P&W necessitam de resistência para suportar o processo de produção e também de uso final. Não só a qualidade do produto final é importante, mas também se busca constantemente aumento na produção. O objetivo deste estudo foi avaliar uma nova técnica que alia ganhos de rendimento com ganhos em propriedades da polpa. Foi estudada a deposição de xilanas em polpas de eucalipto durante a deslignificação com oxigênio. Foram utilizadas três polpas industriais de eucalipto (duas polpas marrons e uma branqueada). As xilanas foram extraídas de polpa marrom ou branqueadas pelo processo CCE (Cold Caustic Extraction = Extração Cáustica a Frio). Os extratos contendo xilanas foram aplicados a uma amostra de polpa marrom na etapa de deslignificação com oxigênio. Estudaram-se os mais importantes parâmetros da deslignificação com oxigênio (tempo, temperatura e carga de álcali) e suas influências na deposição de xilanas. Foram realizados estudos estruturais das xilanas isoladas e seus efeitos na refinabilidade da polpa. Obtiveram-se altos níveis de deposição das xilanas extraídas de polpas branqueadas (WXL White Xylans Liquor), independentemente das condições operacionais utilizadas na deslignificação com oxigênio. O nível de deposição das xilanas extraídas de polpa marrom (BXL Brown Xylans Liquor) foi influenciado negativamente pelo aumento do pH da deslignificação com oxigênio. As polpas que receberam as xilanas WXL apresentaram melhores desempenhos nas operações de branqueamento e refino e melhores propriedades físicas em relação às extraídas de BXL. As xilanas WXL apresentam menos grupos laterais, o que influenciou positivamente as suas deposições e estabilidade durante o branqueamento e refino, resultando menores perdas em relação às xilanas BXL. Foi concluído que a deposição de xilanas na deslignificação com oxigênio apresenta viabilidade técnica, pois é efetiva e não requer grandes instalações/mudanças na linha de fibras. Porém a viabilização econômica depende da disponibilidade de xilanas de baixo custo, extraídas, por exemplo, de resíduos agrícolas ou rejeitos fibrosos da indústria de polpa.Eucalyptus kraft pulps are widely used for printing and writing (P & W). P & W papers need strength to support the production process and also end-use. Not only the quality of the final product is important, but also the constantly search to increase the production. The aim of this study was to evaluate a novel technique that combines yield gains with paper properties gains. Xylans deposition onto eucalyptus pulp fibers during oxygen delignification was studied. Three industrial eucalyptus pulps (two Brown and one bleached). The xylans were extracted from brown and bleached pulps by the CCE process (Cold Caustic Extraction). The liquor containing large amounts of xylan was used instead of water in the oxygen delignification. The most important parameters of oxygen delignification (time, temperature and alkali) and their influence on deposition of xylans were studied. Structural studies of isolated xylans and its influence on the deposition levels and pulp refinability were carried out. High deposition levels of the xylans extracted from bleached pulp (WXL White Xylans Liquor), regardless of the operational conditions used in the oxygen delignification. The deposition levels of the xylans extracted from brown pulp (BXL Brown Xylans Liquor) was negatively influenced by increasing pH of oxygen delignification. The pulps treated with WXL showed better performance on bleaching and refining operations, as well as in paper properties. WXL xylans had less side groups, which positively influenced deposition levels and stability across bleaching and refining operations, resulting in lower losses comparing to the BXL xylans. It was concluded that xylans deposition during oxygen delignification shows technical feasibility, because it is effective and there is no need of big changes/additions to the fiberline. However, the economic viability depends on low-cost xylans availability, for example, from agricultural wastes or mill fibrous rejects

Effect of fiber wall chemistry on pulping processes of novel Eucalyptus hybrids

This thesis investigates relevant issues regarding the use of Eucalyptus wood: the factors affecting energy consumption during wood defibration, with focus on fiber wall chemistry and the assessment of wood quality from a wide range of novel Brazilian Eucalyptus hybrids. The obtained results are reflected to mechanical and traditional chemical processes. Wood refining experiments were carried out in laboratory scale, with and without chemical pretreatment: alkaline peroxide mechanical pulping (APMP) and thermomechanical pulping (TMP) processes, respectively. The most important finding was the direct influence of the lignin structure on the defibration energy. Especially, the relative contents of the guaiacyl moieties in the wood lignin seem to play a crucial role. The results showed that the higher the amount of guaiacyl structures in the lignin, especially in the middle lamella between the fibers, the higher the specific energy consumption (SEC) in the APMP process. However, for the TMP process the correlation was not as clear. This is most probably due to the fact that in the APMP process the defibration takes place in the middle lamella while in the TMP process other mechanism prevails. However, in the samples with very low amount of guaiacyl structures, SEC decreased substantially also in the TMP process. A different approach was promoting fiber wall deconstruction via autohydrolysis of wood. The autohydrolysis process changed notably the mechanical properties of the Eucalyptus chips, with impressive SEC decrease. Although autohydrolysis was performed under mild temperature (120 oC), lignin structure was changed. This assumption was based on the characterization of the fiber surfaces via x-ray photoelectron spectroscopy (XPS). Results showed high coverage of the fiber surfaces with lignin, indicating that the defibration of autohydrolyzed Eucalyptus wood chips takes place along the middle lamella. This behavior differs from the traditional thermomechanical pulping, where the rupture occurs mostly in the fiber wall (especially in the S1 layer), being similar to chemimechanical processes. As a final step, traditional kraft pulping was performed, alongside with soda-anthraquinone (NaOH-AQ) pulping, with focus on the surface properties of the produced fibers, analyzed by SEM and XPS. The surface lignin content of NaOH-AQ pulp fibers was lower than that of the kraft counterpart. However, kraft pulp handsheets showed better physical and mechanical properties. XPS data (C2/C3 ratio) strongly suggested, together with the pulp bulk chemical composition that xylan is more abundant on the surface of kraft fibers, probably enhancing their mechanical properties

Advanced Fractionation of Kraft Lignin by Aqueous Hydrotropic Solutions

Lignin is an underutilized high-potential biopolymer that has been extensively studied over the past few decades. However, lignin still has drawbacks when compared with well-known petroleum-based equivalents, and the production of tailored lignin fractions is highly in demand. In this work, a new method for the fractionation of Lignoboost Kraft Lignin (LKL) is proposed by using two different hydrotropes: sodium xylenesulfonate (SXS) and sodium cumenesulfonate (SCS). The different fractions are obtained by sequentially decreasing the hydrotropic concentration with the addition of water. Four and three different fractions were retrieved from the use of SXS and SCS, respectively. The LKL and respective fractions were analysed, and compared by GPC, FTIR-ATR, 1H-NMR, 13C-NMR, 31P NMR, 2D HSQC and SEM. The fractions showed different molecular weights, polydispersity, and amount of functional groups. Our water-based lignin fractionation platform can potentially be combined with different lignin extraction and processing technologies, with the advantage of hydrotrope recycling

The AD(EO)D process - a new concept

Nesse estudo, investigaram-se cozimentos da madeira até números kappa 17 e 14 por um processo cineticamente modificado, eliminação da deslignificação com oxigênio da linha de fibras, e aplicação das técnicas AD(EO)D e AD(PO)D para polpa de kappa 17 e AD(EO)D e DHT(EPO)DP para polpa de kappa 14 para o branqueamento até 90% ISO. Como referências, foram realizados cozimentos até números kappa 17 e 14, deslignificação com oxigênio em simples estágio e branqueamento convencional pelas seqüências A/D(EO)D, A/D(EPO)D, A/D(EO)DP e A/D(EPO)DP para a polpa de kappa 17 e deslignificação com oxigênio em simples estágio e branqueamento convencional pela seqüência DHT(EPO)DP para polpa de kappa 14. Para a polpa de kappa 17, concluiu-se que os processos AD(EO)D e AD(PO)D produzem polpa de alvura 90% ISO com boa viscosidade e estabilidade de alvura, utilizando TAC´s (Cloro Ativo Total) relativamente baixos, e dispensam completamente a deslignificação com oxigênio. Dentre esses dois processos, o primeiro se mostrou mais atrativo para atingir o nível de alvura de 90% ISO. Porém, comparativamente aos processos de referência, contendo a deslignificação com oxigênio, ex. OA/ D(EPO)DP, o processo AD(EO)D resulta em aumento do custo operacional da ordem de US$7-8/tas, inclusos madeira e reagentes. Para a polpa de número kappa 14, o processo AD(EO)D também se mostrou atrativo, sendo que a seqüência DHT(EPO)DP foi a que utilizou o menor TAC`s, porém quando comparada com a referência (O-DHT(EPO)DP) resultou num aumento de custo operacional da ordem de US$4/tas. Portanto, pode se concluir que o processo alternativo, sem a deslignificação com oxigênio, é viável somente para polpas de números kappa mais baixos.In this study, cooking of the wood had been investigated until kappa numbers 17 and 14 for a process kinetically modified, elimination of oxygen delignification from the fiber line, and application of AD(EO)D and AD(PO)D techniques for pulp of kappa 17 and AD(EO)D and DHT(EPO)DP for pulp of kappa 14 for the bleaching at 90% ISO. As references, cookings had been carried out until kappa number 17 and 14, oxygen delignification in simple stage and conventional bleaching with sequences A/D(EO)D, A/D(EPO)D, A/D(EO)DP and A/D(EPO)DP for the kappa number 17 pulp and oxygen delignification in simple stage and conventional bleaching sequence DHT(EPO)DP for pulp of kappa 14. For the pulp of kappa 17, one concluded that processes AD(EO)D and AD(PO)D produced pulp of brightness 90% ISO with good viscosity and brightness stability, using TAC´s (totally active chloro) relatively low, and it’s not necessary the oxygen delignification. Amongst these two processes, the first one revealed to be more attractive to reach the level of 90% ISO brightness. However, comparatively to the reference processes, with oxygen delignification, for example O-A/D(EPO)DP, process AD(EO)D results in increase of the operational cost of the order of US$7-8/odt, including wood and reagents. For the kappa number 14 pulp, process AD(EO)D also revealed to be attractive, but the sequence DHT(EPO)DP was the one that used lower TAC`s; however, when compared with the reference (O-DHT(EPO)DP), it resulted in an increase of operational cost of the order of US$5/odt. Therefore, it can be concluded that the alternative process, without the deslignification with oxygen, is viable only for pulps of lower kappa number

O PROCESSO AD(EO)D - UM NOVO CONCEITO

In this study, cooking of the wood had been investigated until kappa numbers 17 and 14 for a process kinetically modified, elimination of oxygen delignification from the fiber line, and application of AD(EO)D and AD(PO)D techniques for pulp of kappa 17 and AD(EO)D and DHT(EPO)DP for pulp of kappa 14 for the bleaching at 90% ISO. As references, cookings had been carried out until kappa number 17 and 14, oxygen delignification in simple stage and conventional bleaching with sequences A/D(EO)D, A/D(EPO)D, A/D(EO)DP and A/D(EPO)DP for the kappa number 17 pulp and oxygen delignification in simple stage and conventional bleaching sequence DHT(EPO)DP for pulp of kappa 14. For the pulp of kappa 17, one concluded that processes AD(EO)D and AD(PO)D produced pulp of brightness 90% ISO with good viscosity and brightness stability, using TAC's (totally active chloro) relatively low, and it's not necessary the oxygen delignification. Amongst these two processes, the first one revealed to be more attractive to reach the level of 90% ISO brightness. However, comparatively to the reference processes, with oxygen delignification, for example O-A/D(EPO)DP, process AD(EO)D results in increase of the operational cost of the order of US$7-8/odt, including wood and reagents. For the kappa number 14 pulp, process AD(EO)D also revealed to be attractive, but the sequence DHT(EPO)DP was the one that used lower TAC's; however, when compared with the reference (O-DHT(EPO)DP), it resulted in an increase of operational cost of the order of US$5/odt. Therefore, it can be concluded that the alternative process, without the deslignification with oxygen, is viable only for pulps of lower kappa number

EFFECTS OF XYLAN IN EUCALYPTUS PULP PRODUCTION

The search for a better use of wood in the pulp industry has fuelled interest in a more rational use of its components, particularly xylans. The impact of xylans removal and of xylans redeposition on pulp properties for tissue and P&W paper grades are discussed in this paper. Kraft pulp (15.6% xylans) treatment with 10-70 g.L-1 NaOH resulted in pulps of 14.5-5.9% xylans. The treatments decreased pulp lignin and HexA contents and caused significant positive impact on subsequent oxygen delignification and ECF bleaching. Xylan removal decreased pulp beatability, water retention value and tensile index but increased drainability, water absorption capacity, capillarity Klemm and bulk. Overall, xylan depleted pulps showed almost ideal properties for tissue paper grade pulps. In a second step of the research, xylans extracted from unbleached (BXL) and bleached eucalyptus pulps (WXL) by cold caustic extraction (CCE) were added to a commercial brown pulp in the oxygen delignification (O-stage) and further bleached. Xylans deposition occurred at variable degree (up to 7% on pulp weight) depending upon the O-stage reaction pH. Pulp bleachability was not impaired by WXL xylan deposition but slightly negatively affected by BXL xylans. Pulp beatability was improved by xylan deposition. The deposited xylans were quite stable across bleaching and beating, with the WXL xylans being more stable than the BXL ones. At low energy consumption, the deposited xylans improved pulp physical and mechanical properties. Xylans extraction by CCE with subsequent deposition onto pulp in the O-stage proved attractive for manufacturing high xylan P&W paper grades. \u