Submitted by (ana.araujo@ufrpe.br) on 2016-08-17T12:29:26Z No. of bitstreams: 1 Ulisses Vieira Guimaraes.pdf: 877634 bytes, checksum: cafb89d2c3ac8722437ff1ee2a838a65 (MD5) / Made available in DSpace on 2016-08-17T12:29:26Z (GMT). No. of bitstreams: 1 Ulisses Vieira Guimaraes.pdf: 877634 bytes, checksum: cafb89d2c3ac8722437ff1ee2a838a65 (MD5) Previous issue date: 2010-02-10 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / The objective of this study was to assess the magnitude of the interaction between genotypes of cane sugar and environments and the adaptability and stability to the character of total sugar recovered (TSR) using the methodology proposed by Wricke (1965), Eberhart and Russell (1966), Cruz, Torres and Vencovsky (1989) and Annic-chiarico (1992). It was evaluated eight genotypes of sugar cane cultivated in Usina Trapiche in the State of Pernambuco and Usina Serra Grande in the State of Ala-goas. The experimental design was a randomized block design with four blocks during the period 2004 to 2008, referring to cuts, sugarcane, ratoon, second ratoon cane and fourth leaf, respectively. It was observed differences among genotypes within each environment. The evaluation of genotypes, has highlighted the G8 genotype to obtain the average productivity of TSR above the overall average, adaptable and suitable for all types of environments, according to Eberhart and Russell (1966), Cruz et al. (1989) and Annichiarico (1992), and high stability by the methods listed above and Wricke (1965). The G5 was the most productive, adaptable to all types of envi-ronments, but as it presents low stability, its behavior is unpredictable. At unfavorable environments, the genotype G4 was the best, with high productivity and good rre-sponse to environmental changes. It was noted a strong association between the results of the methods Eberhart and Russell (1966) and Cruz et al. (1989), which are based on linear regression analysis and simple linear regression bissegmented re-spectively. The use of methods of adaptability and stability in combination can be interesting and add information about the performance of genotypes evaluated, how-ever, the use of these methods, based on the same statistic is not recomendable. / O objetivo deste trabalho foi o de avaliar a magnitude da interação entre genótipos de cana-de-açúcar e ambientes e a adaptabilidade e estabilidade para o caráter açúcares totais recuperados (ATR) por meio dos métodos propostos por Wricke (1965), Eberhart e Russell (1966), Cruz, Torres e Vencovsky (1989) e Annicchiarico (1992). Foram avaliados oito genótipos de cana-de-açúcar cultivados na Usina Trapiche no Estado de Pernambuco e Usina Serra Grande no Estado de Alagoas. O delineamento estatístico utilizado foi o de blocos ao acaso com quatro repetições durante o período de 2004 a 2008, referentes aos cortes: cana-planta, cana-soca, cana-ressoca e quarta folha, respectivamente. Verificou-se a existência de diferenças significativas entre os genótipos dentro de cada ambiente. Dos genótipos avalia-dos, tem-se em destaque o genótipo G8 por obter a média de produtividade de ATR acima da média geral, adaptável e recomendado para todos os tipos de ambientes, segundo os métodos Eberhart e Russel (1966), Cruz et al. (1989) e Annichiarico (1992), e alta estabilidade segundo os métodos já citados e Wricke (1965). O G5 foi o mais produtivo, adaptável a todos os tipos de ambientes, no entanto apresenta baixa estabilidade, isto é, seu comportamento é imprevisível. Em ambientes desfavoráveis, se destaca o genótipo G4, com alta produtividade e responde bem às mu-danças ambientais. Notou-se uma forte associação entre os resultados dos métodos Eberhart e Russell (1966) e Cruz et al. (1989), sendo estes baseados em análise de regressão linear simples e regressão linear bissegmentada, respectivamente. A utilização de métodos de análise de adaptabilidade e estabilidade de forma combinada pode ser interessante e agregar informações a respeito do comportamento dos genótipos avaliados, no entanto, o uso desses métodos, baseados em mesma estatística, é desaconselhável.

Abstract The amount of printing ink in a pulp suspension produced from recovered paper and its impact on overall brightness is commonly estimated from the reflectance-based ink content measured at a wavelength of 700 nm or 950 nm. The method uses a light scattering coefficient that can be measured from a slightly translucent test medium, i.e. of an opacity less than 97%. This is the case with machine-made papers in most instances. Alternatively, suitable opacity can be achieved by preparing a standard low-grammage sheet on a wire screen, but this results in poor retention of fibre fines, mineral fillers and printing inks, which is especially detrimental to ink measurement when the pulp suspension contains substantial amounts of printing inks. Hence opaque pads are often prepared on filter paper to achieve high retention. Unfortunately their high opacity prevents measurement of the light scattering coefficient, and thus a constant coefficient must be used for the determination of ink content. The aim of this thesis was to clarify the effects of retention and fine material changes on the light scattering coefficient in ink content measurement. The results showed that the light scattering properties of pulp in the wavelength region used for ink content analysis do not remain constant when the fine material content varies. The grade of the recovered paper, hyperwashing and flotation alter the fine material content and thus affect the light scattering. Printing ink also affects light scattering, but its practical impact is smaller than that of fibre fines and mineral fillers. The light scattering coefficient used for each ink content measurement needs to be representative, otherwise a systematic bias in ink content measurements may result from changes in the nature of the fine material and in its content. It is recommended that the light scattering coefficient should be measured in order to avoid this. The measurement should preferably be performed from a low-grammage sheet prepared on filter paper, as this ensures high retention and a measured value that represents better the initial state of the pulp suspension. / Tiivistelmä Mustepitoisuusmittaus perustuu hajaheijastukseen joko 700 nm tai 950 nm aallonpituudella ja sitä käytetään usein arvioitaessa keräyspaperista valmistetun massasuspension soveltuvuutta painopaperien valmistukseen ja painomusteen vaikutusta massan vaaleuteen. Mustepitoisuuden mittauksessa käytetään valonsirontakerrointa, joka voidaan mitata hieman läpikuultavasta näytteestä eli näytteen opasiteetin on oltava pienempi kuin 97 %. Tämä opasiteettiraja toteutuu useimmiten paperikoneella tehdyille painotuotteille. Riittävän alhainen opasiteetti saavutetaan myös valmistamalla standardin mukainen matalaneliömassainen arkki viiralle, mutta tämä johtaa kuitumaisten hienoaineiden, mineraalisten täyteaineiden ja painomusteiden alhaiseen retentioon. Matala retentio on erityisen haitallinen piirre mustemittauksen kannalta massoilla, jotka sisältävät huomattavia määriä painomusteita. Siten usein valmistetaan läpikuultamattomia arkkeja suodatinpaperin päälle, joiden retentio on korkea. Korkeasta opasiteetista johtuen näistä arkeista ei voida määrittää valonsirontakerrointa, jolloin mustepitoisuuden määritys perustuu vakiokertoimeen. Tämän väitöskirjan tavoitteena oli selvittää retention ja hienoaineiden muutoksien vaikutuksia valonsirontakertoimeen ja mustemittaustulokseen. Tutkimuksen tulokset osoittivat että valonsirontakerroin, joka mitataan mustepitoisuuden yhteydessä, ei pysy vakiona hienoainepitoisuuden muuttuessa. Hienoainepitoisuuteen ja siten valonsirontakertoimeen vaikuttavat keräyspaperin laji, hyperpesu ja vaahdotus. Myös painomuste vaikuttaa valonsirontakertoimeen, mutta käytännössä vaikutuksen suurusluokka on pienempi kuin hieno- ja täyteaineilla. Mustepitoisuuden määrityksessä käytetyn valonsirontakertoimen on oltava edustava, muutoin arvot voivat olla systemaattisesti virheellisiä hienoainemäärän tai laadun muuttuessa. Virheen välttämiseksi olisi suositeltavaa määrittää valonsirontakerroin mustepitoisuusanalyysin yhteydessä. Tämä olisi mahdollista tehdä suodatinpaperin päälle valmistetusta matalaneliömassaisesta arkista, jolloin saavutetaan korkea retentio ja näin mitattu arvo edustaa paremmin massasuspension alkuperäistä tilaa.

Abstract The aim of the deinking process is to produce deinked pulp from recovered papers (RCPs) with sufficient brightness and cleanliness to fulfil the quality requirements set by the paper grade to be produced. Due to the excessive production costs and material losses of modern deinking processes, there is a need to simplify deinking lines. A prerequisite for this action is that ink content bound to fibres, dirt content and ink fragmentation are minimised in the pulping stage. Thus, it is important to recognise the factors affecting ink behaviour in pulping, to search for new ways to improve ink detachment from RCPs in pulping and to search pulping methods that could efficiently process RCPs printed with various inks. The aim of this thesis was to obtain new information on how the environmental conditions that prevail during the storage and transportation of RCPs affect ink behaviour in subsequent pulping and to find out whether there is further potential to decrease ink content bound to fibres, not only by treating recovered papers chemically before the actual pulping process, but also by removing the detached ink particles during the pulping process. The results show that if some RCPs are very moist and exposed to high temperatures for a reasonable time before the pulping process, the problems in releasing ink from the fibres in pulping become more pronounced and the pulp is dirtier compared to pulp from RCPs that are thermally aged but dry. Properly wetting some RCPs with conventional alkaline deinking chemicals in suitable conditions ahead of the pulping process reduces the ink content that remains bound to the fibres after the pulping process. The efficiency of the pre-wetting treatment in aiding ink detachment from fibres in subsequent pulping is highly dependent on the alkalinity, temperature and duration of the treatment. Semi-continuous ink removal during the pulping process offers the possibility to continue defibering, ink detachment from fibres and dirt fragmentation in pulping without fear of ink redeposition into or onto the fibres, thus resulting in fully disintegrated pulp with lower ink content bound to fibres than in conventional pulping. This enables efficiently simultaneous processing of, for example, papers printed with water-based inks and toners. / Tiivistelmä Siistausprosessin tavoitteena on tuottaa keräyspapereista valmistettua vaaleaa ja puhdasta massaa, jota voidaan käyttää uusien paperituotteiden valmistamiseen. Siistausprosesseja pyritään yksinkertaistamaan nykyisten monimutkaisten prosessien korkeiden tuotantokustannusten ja materiaalitappioiden vuoksi. Eräs edellytys siistausprosessien yksinkertaistamiselle on, että kuiduissa kiinni olevan musteen pitoisuus, massan likapitoisuus ja musteen liiallinen pilkkoutuminen minimoidaan siistausprosessin ensimmäisessä vaiheessa, pulpperoinnissa. Täten on tärkeää tunnistaa musteen käyttäytymiseen pulpperoinnissa vaikuttavat tekijät, etsiä uusia mahdollisuuksia parantaa musteen irrotusta keräyspapereista sekä kehittää pulpperointimenetelmiä, joilla voitaisiin prosessoida tehokkaasti eri painomenetelmillä painettuja papereita. Tämän työn tavoitteena oli saada uutta tietoa siitä miten ympäristöolosuhteet, joille keräyspaperit voivat altistua varastoinnin ja kuljetuksen aikana, vaikuttavat musteen käyttäytymiseen pulpperoinnissa. Lisäksi tavoitteena oli selvittää voitaisiinko kuituihin kiinni jääneen musteen pitoisuutta vähentää esiliottamalla keräyspapereita sopivissa kemiallisissa olosuhteissa ennen pulpperointia ja poistamalla irronneet mustepartikkelit massan seasta pulpperoinnin aikana. Tulokset osoittavat, että jos tietyt keräyspaperit ovat erittäin kosteita ja altistuvat korkealle lämpötilalle riittävän pitkän ajan ennen pulpperointia, tulee musteen irrottaminen kuiduista pulpperoinnissa vaikeammaksi ja tuotettu massa likaisemmaksi, kuin sellaisista keräyspapereista, jotka ovat altistuneet kuivina korkealle lämpötilalle. Kuituihin kiinnittyneen musteen pitoisuutta voidaan vähentää esiliottamalla tiettyjä keräyspapereita alkalisilla siistauskemikaaleilla sopivissa olosuhteissa ennen pulpperointia. Esiliotuksen kyky parantaa musteen irrotusta kuiduista pulpperoinnissa riippuu voimakkaasti esiliotusvaiheen alkalisuudesta, lämpötilasta ja kestosta. Kun irronneet mikroskooppiset mustepartikkelit poistetaan massasta useassa vaiheessa pulpperoinnin aikana, voidaan paperin kuidutusta, musteen irrottamista kuiduista ja likapilkkujen hajottamista jatkaa ilman että haitallista musteen takaisin kiinnittymistä kuituihin tapahtuu. Tämä mahdollistaa esimerkiksi vesipohjaisten musteiden ja lasertulosteiden samanaikaisen prosessoinnin.

We consider a posteriori error estimators that can be applied to anisotropic tetrahedral finite element meshes, i.e. meshes where the aspect ratio of the elements can be arbitrarily large. Two kinds of Zienkiewicz-Zhu (ZZ) type error estimators are derived which are both based on some recovered gradient. Two different, rigorous analytical approaches yield the equivalence of both ZZ error estimators to a known residual error estimator. Thus reliability and efficiency of the ZZ error estimation is obtained. Particular attention is paid to the requirements on the anisotropic mesh. The analysis is complemented and confirmed by several numerical examples.

Selon la European Tyre Recycling Association (ETRA), plus de 3 millions de tonnes de pneus en fin de vie sont à traiter en Europe chaque année et sont directement concernés par les mesures législatives visant le réemploi et la valorisation de 95 % de la masse totale des véhicules hors d'usage. Malgré les différentes possibilités de valorisation des pneus usagés (applications dans le secteur du bâtiment et travaux publics, valorisation matière, valorisation énergétique), une partie du gisement français n’est pas répertorié, ni valorisé, et aucune des voies citées auparavant ne s’intéresse à la récupération du noir de carbone, qui est un constituant essentiel du pneu. Ce produit, à forte valeur ajoutée, est principalement utilisé comme charge de renfort dans l'industrie du caoutchouc et des plastiques. Il existe deux types de procédés thermiques industrialisés permettant de récupérer le noir de carbone d’un pneumatique en fin de vie : la pyrolyse et la vapo-thermolyse. La vapo-thermolyse, actuellement industrialisée par Alpha Recyclage Franche Comté (ARFC), est une variante innovante de la pyrolyse, qui utilise la vapeur d’eau surchauffée à pression atmosphérique. La solution qui consiste à substituer un noir de carbone issu d’un procédé de fabrication conventionnel par un noir de carbone issu de vapo-thermolyse de pneus repose sur la qualité du noir de carbone récupéré et, en particulier, sur ses propriétés physico-chimiques intrinsèques et de surface. L'objectif de ce travail de thèse est de proposer et mettre en place une méthodologie adéquate afin de récupérer et caractériser les propriétés physico-chimiques du noir de carbone recupéré (rCB) par vapo-thermolyse à partir d'une formulation de pneu, d'évaluer l'impact des conditions de fonctionnement du procédé sur les propriétés du rCB, et enfin de valoriser le rCB en tant que charge de renfort alternative pour l'élaboration d'un produit final. / According to the European Tyre Recycling Association (ETRA), more than 3 millions tonnes of waste tires are to be treated in Europe each year and are subject to legislation and regulation policies for the re-use and recycling of 95 % of the total mass of end-of-life vehicles. Despite the various opportunities for recycling used tires (civil engineering applications, material recovery, energy recovery), a part of the French available resource remains unvalued and none of the applications just mentioned focuses specifically on the recovery of carbon black, which is one of the main component of a tire. This high added value product is mainly used as reinforcing filler in the rubber and plastics industries. There are two types of industrialized thermal processes for recovering the carbon black from an end-of-life tire : pyrolysis and steam thermolysis. Steam thermolysis, currently industrialized by Alpha Recyclage Franche Comté (ARFC), is an efficient pyrolysis alternative which uses superheated steam at atmospheric pressure. The substitution of carbon blacks produced from a conventional manufacturing process by carbon blacks recovered from the steam thermolysis treatment is based upon the quality of the recycled product, especially regarding its physicochemical properties (intrinsic and surface). The objective of this work is to propose and implement an adequate methodology to recover and characterize the physicochemical properties of recovered carbon black (rCB) from steam thermolysis of a tire, to assess the impact of the process operating conditions on the properties of the rCB, and finally to valorize the rCB as an alternative reinforcing filler for the elaboration of a final product.

La diminution de la qualité des collectes des papiers récupérés ainsi que l’accumulation de substances dissoutes dans les eaux de procédés affecte l’efficacité des lignes de désencrage industrielles et contamine davantage les effluents liquides. Dans ce contexte, le LGP2 a développé depuis quelques années un procédé innovant de désencrage, la flottation réactive à l’ozone, afin de dégrader chimiquement les polluants dissouts en parallèle de l’élimination de l’encre. Afin de mieux comprendre les mécanismes mis en jeu, des essais de flottation à l’air et à un mélange ozone/oxygène, sur trois contaminants modèles, sélectionnés après une étude bibliographique préalable, ont été réalisés dans un milieu diphasique gaz/liquide, en l’absence de fibres cellulosiques. Les expérimentations ont été conduites sur deux pilotes de laboratoire instrumentés : une colonne à bulles fonctionnant avec de l’air uniquement, pour l’étude du comportement hydrodynamique (taille et distribution de bulles, rétention gazeuse) en présence des contaminants dissouts, et une deuxième colonne à bulles, similaire mais conçue avec des matériaux résistants aux gaz corrosifs, dédiée à l’étude des réactions d’oxydation en présence d’ozone. L’examen du comportement hydrodynamique montre que les conditions de débit de gaz et d’injection retenues conduisent à des tailles de bulles optimales pour une flottation efficace, que ce soit en présence ou absence de contaminants. Ces conditions obtenues avec de l’air ont été transposées en première approximation au système ozone/oxygène. L’étude du transfert de l’ozone et de sa réactivité avec les trois contaminants modèles, à différentes températures et concentrations en ozone, a conduit à la détermination des constantes cinétiques de réaction et a montré que les contaminants étaient, selon leur nature, oxydés ou dépolymérisés. Bien que la DCO des solutions traitées diminue très peu après la flottation réactive à l’ozone, la qualité des effluents est améliorée sur le plan de leur biodégradabilité. / The decrease of the recovered paper collection quality and the accumulation of dissolved substances in process water affect the deinking line efficiency and contaminate more and more the liquid effluents. In this context the LGP2 has developed an innovative deinking process, the ozone reactive flotation, to chemically degrade dissolved pollutants in parallel with ink removal. To better understand the mechanisms involved, air and ozone/oxygen flotation trials have been conducted on three model contaminants selected in a preliminary bibliographic review, in a two-phase gas/liquid system, in the absence of fibers. Experiments have been carried out on two instrumented laboratory pilots: a bubble column operating only with air for the study of the hydrodynamics of the reactor (bubbles size and distribution, gas hold-up) in the presence of dissolved contaminants, and a second one, similar in its conception but built using materials resistant to corrosive gas, dedicated to the study of the oxidation reactions with ozone. The evaluation of the hydrodynamics related to gas flow and injection system selected, studied with air but supposed to be the same with ozone/oxygen gas mixture, shows that the bubble size, with or without contaminants, is optimal for an efficient flotation process. The study of ozone mass transfer and reactivity with the three model contaminants, for several temperatures and ozone concentrations, leads to the calculation of kinetic constants and shows that the contaminants, depending on their nature, have been oxidized or depolymerized. Although the COD of the treated solutions does not decrease a lot after the ozone reactive flotation, the effluent quality has been improved in terms of biodegradability since contaminants are partially degraded.

The Japanese paper and paperboard industry has grown to be one of the largest in the world. It manufactures a range of products for sale primarily within Japan, and consumes organic fibre for these products from dispersed domestic and foreign forests, plantations and cities. This dissertation examines the links between the development and structure of the industry and its use of papermaking fibre. It takes a political ecology perspective and uses an industrial structure/consumption-production chain approach to show how the industry’s development and structure continue to depend on company control over fibre flows and the restructuring of products, product distribution and manufacture, the fibre supply chain and fibre resources. As with the modern global paper/board industry, the recent growth of the Japanese industry has been characterised by cycles of capacity expansion, market collapse, excess capacity and low prices and profits. Manufacturers and general trading companies involved in the industry have tried to support growth in the use of paper/board and counter these cycles by restructuring production, distribution, ownership and fibre supply. This restructuring helps protect the flow of fibre through the industry and concentrated it in particular companies. Obtaining increasing quantities of suitably-priced fibre has been at the base of the industry’s development.

The Japanese paper and paperboard industry has grown to be one of the largest in the world. It manufactures a range of products for sale primarily within Japan, and consumes organic fibre for these products from dispersed domestic and foreign forests, plantations and cities. This dissertation examines the links between the development and structure of the industry and its use of papermaking fibre. It takes a political ecology perspective and uses an industrial structure/consumption-production chain approach to show how the industry’s development and structure continue to depend on company control over fibre flows and the restructuring of products, product distribution and manufacture, the fibre supply chain and fibre resources. As with the modern global paper/board industry, the recent growth of the Japanese industry has been characterised by cycles of capacity expansion, market collapse, excess capacity and low prices and profits. Manufacturers and general trading companies involved in the industry have tried to support growth in the use of paper/board and counter these cycles by restructuring production, distribution, ownership and fibre supply. This restructuring helps protect the flow of fibre through the industry and concentrated it in particular companies. Obtaining increasing quantities of suitably-priced fibre has been at the base of the industry’s development.

Les usines récupérées par les ouvriers en Argentine sont devenues un mouvement social emblématique symbolisant l'un des aspects de la révolte sociale entourant la crise économique de 2001-2002. Les usines récupérées sont des entreprises abandonnées par leurs propriétaires originaux ou déclarées faillite, laissant derrières elles des salaires et des dettes impayés. Par conséquence, les ouvriers ont commencé à récupérer leurs usines; reprenant la production sans leurs anciens patrons, sous, et au profit de la gestion collective des ouvriers. Le mouvement est remarquable pour sa rémunération égalitaire et sa gestion horizontale. Ce travail examine la continuité des usines récupérées et ceci à travers l'évolution sociale, politique et économique du paysage de l'Argentine. Il évalue également l'impact du mouvement en tant que défi aux modes économiques de production hégémoniques et orientés vers le marché. En supposant que l'avenir du mouvement dépend de deux ensembles de facteurs, le rapport analyse les facteurs internes à travers le prisme de la théorie de mobilisation des ressources, ainsi que les facteurs externes à travers la perspective de la théorie de la structure de l'opportunité politique. Le travail conclut que la situation actuelle se trouve dans une impasse dans laquelle le mouvement a gagné l'acceptation institutionnelle, mais a échoué d'effectuer le changement structurel favorisant ses pratiques et garantissant la sécurité à long terme. Il argumente que le mouvement doit consolider certains aspects combatifs. Il doit consolider sa nouvelle identité en tant que mouvement social et forger des alliances stratégiques et tactiques tout en préservant son autonomie. / The worker-recovered factories of Argentina became an emblematic social movement symbolizing one of the aspects of the social upheaval surrounding the economic crisis of 2001-2002. The recovered factories are enterprises abandoned by their original owners or declared bankrupt, leaving behind unpaid wages and trailing debts. In response, workers began recuperating their factories; resuming production without their former bosses, under, and for the benefit of, a collective worker management. The movement is remarkable for its egalitarian remuneration and its horizontal management. This paper examines the continuity of the recovered factories through the evolving social, political and economic landscape of Argentina. It also assesses the impact of the movement as a challenge to the hegemonic, market-oriented, economic modes of production. Assuming that the future of the movement depends on two sets of factors, the paper analyses internal factors through the prism of resource mobilization theory and external factors from the perspective of political opportunity structure theory. The work concludes that the current situation is one of stalemate, in which the movement gained institutional acceptance, but failed to effect structural change favouring its practices and guaranteeing long-term security. It argues that the movement needs to consolidate certain combative aspects. It must consolidate its new identity as a social movement and forge strategic and tactical alliances while preserving its autonomy.

La desintegració és una etapa important en la recuperació de paper vell, ja que té importants conseqüències en consum d'energia i en el comportament de les etapes posteriors.Per això els objectius es centren en analitzar la desintegració des del punt de vista del temps de desintegració, els aspectes energètics, modelització de la màquina de desintegració utilitzada i anàlisi dels factors de cisallament calculats com a mesura global de les forces implicades en la desintegració. Els autors que hi han treballat donen diferents explicacions a aquestes forces. Fins avui només s'ha pogut avaluar qualitativament la influència que tenen cada un dels mecanismes en el temps necessari per a desintegrar i en el consum energètic. Les característiques reològiques de les suspensions papereres, i el seu comportament no newtonià tenen una clara influència en el consum energètic i les forces de desfibrat en el desintegrador.Els experiments de desintegració s'han realitzat en un púlper convencional, amb tres tipus de paper recuperat: paper estucat d'alta qualitat imprès offset (PQ), paper revista estucat imprès en color (PR), paper blanc imprès en impresora làsser (PF).Anàlisi del temps de desintegracióPer cada un del papers estudiats (PQ, PR i PF), les fraccions màssiques des de 0.06 fins a la màxima que estat possible per cada paper (de 0.14 a 0.18), i a dues velocitats d'agitació diferents, s'ha determinat el temps de desintegració (tD) fins a aconseguir un índex de Sommerville de 0.01%. S'obté que en augmentar la fracció màssica disminueix potencialment el temps de desintegració. S'ha estudiat la velocitat de desintegració, la producció teòrica del púlper en cada cas, i la seva relació amb les forces d'impacte i de fregament que produeixen la desintegració.Aspectes energèticsEl consum específic d'energia (SEC), definit com l'energia consumida per a desintegrar 1 kg de paper recuperat, disminueix molt en augmentar Xm, ja que a més de disminuir l'energia consumida en cada desintegració, el contingut en paper és més elevat. Pel disseny de desintegradors, cal tenir en compte que en augmentar Xm i en augmentar la velocitat, sempre augmenta la potència consumida. Però així com els beneficis de treballar a Xm alt són de 10 vegades en termes de SEC i de producció, l'augment de potència és només de l'ordre de 2 vegades la necessària respecte de la Xm baixa. Viscositat aparent i energia de fluiditzacióS'estudia la relació entre el temps de desintegració, les forces de fregament i els valors de viscositat aparent de la bibliografia. Per cada paper i velocitat s'ha observat que el consum específic d'energia disminueix en funció de la viscositat aparent.Reologia del púlperUtilitzant el mètode de Metzner i Otto (1957) per determinar la viscositat aparent mitjana de les suspensions papereres, modificat per Roustan, s'ha caracteritzat el pulper mitjançant el model: Np= K· Rex·Fry S'han utilitzat dissolucions de glicerina com a fluid newtonià per a calcular les constants d'ajust, i a partir d'aquí, aïllar la viscositat aparent en funció de la potència neta i els paràmetres d'agitació.La viscositat aparent, d'acord amb Fabry (1999) es substitueix pel concepte de factor de cisallament.Factor de cisallamentCalculat el factor de cisallament per a cada paperot i condicions d'agitació, s'ha relacionat amb Xm, SEC, tD, consum de potència, potència instal·lada i fracció cel·lulòsica. El factor de cisallament és un paràmetre útil per a quantificar les forces globals implicades en la desintegració. / Disintegration is an important stage in paper recovery and it has important consequences in energy consumption and in the following stages.The objectives of this thesis are focussed in analyzing disintegration considering disintegration time, power aspects, modelisation of the disintegration machine and analysis of the calculated shear factors as a global measurement of the forces implied in the disintegration.Until now, it has only been possible a qualitative evaluation of the influence of every mechanism in the time necessary to disintegrate the pulp, and in the power consumption.Rheological characteristics of suspensions and their non-Newtonian behaviour it is known that clearly influence power consumption and defibering forces acting during repulping. Disintegration experiments have been made in a conventional pulper, with three types of recovered paper: high quality coated printed offset paper, magazine coated colour printed paper and white laser printed paper.Analysis of disintegration timeTime necessary to achieve a Somerville index of 0.01%, was determined for each paper studied, at mass fractions ranging from 0,06 until the maximum possible for each type of paper (0,14 or 0,18) and at two different agitation speeds. It has been found that when increasing the mass fraction, disintegration time decreases potentially. Disintegration speed and theoretical production of pulp have been studied in each case, and they have been related with friction and impact forces.Power aspects Specific energy consumption (SEC) defined as the energy consumed during disintegration of 1 kg of recovered paper, was reduced with increasing mass fraction (Xm), because the energy consumed during disintegration decreases and the pulp contend in the pulper is higher. And increase of Xm and pulper agitation speed always increases the power consumed. An increase of only 2 times of power consumption (due to working at high Xm) produces benefits in SEC and production of 10 times.Apparent Viscosity and fluidisation energy Relation between disintegration time, friction forces and apparent viscosity were studied. For each paper and speed it has been observed that SEC was reduced when increasing apparent viscosity.Rheology of pulper Using Metzner and Otto methodology to determine average apparent viscosity of suspensions, modified by Roustan, pulper was characterized by means of model Np=K·Rex·Fry. Glycerine dissolutions have been used as Newtonian fluid to calculate constants of adjustment, and from here, apparent viscosity was determined from net power and agitation parameters. Apparent viscosity, in agreement with Fabry, is replaced by the concept of shear factor.Shear FactorOnce calculated the shear factor for each type of paper and conditions of agitation, the values obtained have been related to Xm, SEC, td, power consumption, installed power and cellulose fraction. Shear factor is a useful parameter to quantify the global forces acting in disintegration process.