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Stratified forming for lightweight grades is a promising concept, which has the potential to improve the mechanical properties of the sheet. The inner and outer layers of the stratified sheet may consist of deinked pulps fractions... more
Stratified forming for lightweight grades is a promising concept, which has the potential to improve the mechanical properties of the sheet. The inner and outer layers of the stratified sheet may consist of deinked pulps fractions mixtures, with various mechanical and optical properties. The objective of this study is to optimise the sheet structure by stratification to maximise bending stiffness properties. Four DIP fractions either rich in fibres or in fine elements were produced through a fractionation/deinking process. Their intrinsic physical properties were identified from mono-layer handsheets measurements. Then models for the stratified handsheet properties are proposed and validated against multi-layer handsheets measurements. Finally, optimised stratified sheet structure is investigated, while using the entirety of the available DIP fractions mass flows from the fractionation/deinking process.
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The stabilization of air bubbles and foaming in the presence of nonyl phenol ethoxylate surfactants and sodium dodecyl sulphate were investigated by using a laboratory bubble column. Images of air bubbles were taken at increasing... more
The stabilization of air bubbles and foaming in the presence of nonyl phenol ethoxylate surfactants and sodium dodecyl sulphate were investigated by using a laboratory bubble column. Images of air bubbles were taken at increasing surfactant dosage and corresponding bubble size distributions were correlated with surfactant type and concentration, showing that the longer the PEO chain the more pronounced bubble stabilization. Model equations proposed in the literature were used to explain the influence of surfactants molecular structure on liquid film drainage and bubble stabilization. The foaming behaviour of surfactant solutions was evaluated by measuring the thickness of the foam layer generated at the top of the bubble column after 1 min bubbling. Bubble size distributions and bubble retention time in the column were used to interpret the foaming behaviour of tested surfactants, to define a foaming criterion and to draw some conjectures on the role of surfactant structure during flotation de-inking.
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This study pursued two objectives related to deinking. The first objective deals with the application of fractionation for deinking operations rationalization, which requires all free ink separation in one fraction and treatment in ink... more
This study pursued two objectives related to deinking. The first objective deals with the application of fractionation for deinking operations rationalization, which requires all free ink separation in one fraction and treatment in ink removal operations. Following accomplishment of the first objective, the second objective was fractions generation for stratified sheet formation. The first objective requires separation based on length, and the second requires separation by development of surface characteristics. The experimental plan was focused on selective fines separation and further valorization of fiber and fines fractions. It was shown that fractionation by a pressure screening system equipped with a smooth hole basket with 0.25mm perforations was very selective towards fines (free ink, fillers, cellulosic fines) separation in the accepts. Long fibers, as well as specks, were retained in the rejects fraction. Due to the higher selectivity of the micro-hole screen, fibers are r...
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Environmental and economic concerns are driving tissue paper manufacturers to improve understanding of the relationships between fibres, the networks they form, the forming process, and the final tissue paper properties. This work... more
Environmental and economic concerns are driving tissue paper manufacturers to improve understanding of the relationships between fibres, the networks they form, the forming process, and the final tissue paper properties. This work investigated how pulp fractionation, refining, or addition of microfibrillated cellulose (MFC) affect the compromise between absorbency and strength of 33 ± 2 g/m² model papers made of bleached eucalyptus kraft pulp. The results showed that the compromise of properties was better when fibres were refined than when MFC was added. The absorbency capacity of 2%wt MFC-paper was almost 20% lower than the capacity of the refined paper at the same dry strength. The calculated additional storage capacity due to water-induced deformations of the fibre network was 40% lower in the same range of bulk. By forming a high viscosity gel at inter-fibre contacts, MFC could limit the occurrence of major fibre and network deformation mechanisms when water was imbibing the pa...
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HAL - hal.archives-ouvertes.fr, CCSd - Centre pour la Communication Scientifique Direct. Accueil; Dépôt: S'authentifier; S'inscrire. Consultation: Par domaine; Les 30 derniers dépôts; Par année de publication, rédaction, dépôt;... more
HAL - hal.archives-ouvertes.fr, CCSd - Centre pour la Communication Scientifique Direct. Accueil; Dépôt: S'authentifier; S'inscrire. Consultation: Par domaine; Les 30 derniers dépôts; Par année de publication, rédaction, dépôt; Par type de publication; ...
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Les procedes industriels papetiers sont des procedes complexes, qui mettent en œuvre un grand nombre d'appareils. Chacun de ces equipements contribue a produire un flot de pâte liquide a partir duquel la feuille de papier sera... more
Les procedes industriels papetiers sont des procedes complexes, qui mettent en œuvre un grand nombre d'appareils. Chacun de ces equipements contribue a produire un flot de pâte liquide a partir duquel la feuille de papier sera obtenue. Le nombre important de flux assurant le transport de matieres le long du procede, le re-bouclage de ces flux, le nombre de capacites de stockage et leur dimensionnement font qu'il est tres difficile d'analyser et de comprendre le fonctionnement de ces procedes, sans l'aide d'outils dedies a cet usage. L'evolution de l'informatique permet de developper des outils de simulation numerique des procedes industriels. Les operateurs disposent alors d'un procede virtuel qui reproduit plus ou moins precisement -en fonction du niveau de simplification retenu- le fonctionnement du procede reel, a partir duquel ils vont pouvoir tester et evaluer differentes strategies de conduite, sans aucun risque et tres souvent avec des temps de...
Research Interests: Computer Science and Art
A process for the production of paper by forming and dewatering a suspension of cellulose containing fibers and optional fillers on a wire. Three components are added to the suspension, a cationic starch, a cationic polyacrylamide and a... more
A process for the production of paper by forming and dewatering a suspension of cellulose containing fibers and optional fillers on a wire. Three components are added to the suspension, a cationic starch, a cationic polyacrylamide and a polymeric silicic acid, in order to improve retention and dewatering at paper production.
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The use of bleaching chemicals in deinking lines producing wood-containing deinked pulp (DIP) is discussed. An alkaline chemistry including hydrogen peroxide in the pulping stage is efficient as caustic soda helps to ink detachment and... more
The use of bleaching chemicals in deinking lines producing wood-containing deinked pulp (DIP) is discussed. An alkaline chemistry including hydrogen peroxide in the pulping stage is efficient as caustic soda helps to ink detachment and hydrogen peroxide prevents yellowing and increases the brightness. Various bleaching chemicals have been compared to bleach, after a prior deinking, wood-containing DIP, the best bleaching results are obtained with conventional agents such as hydrogen peroxide, sodium hydrosulfite and FAS. Chlorine dioxide, ozone and oxygen induce yellowing and are not suitable. After pulping in alkaline conditions, similar brightness gains are obtained for the reductive agents or the hydrogen peroxide while after pulping in neutral conditions, hydrogen peroxide is more efficient than reducing agents. When bleaching wood-containing DIP with a high content of coloured papers (coloured directories and coloured newspapers), it is not possible in a single bleaching stage ...
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Process waters in deinking mills often feature a strong coloration, due to dyes and pigments released from the recovered paper. This can usually be remediated by pulp bleaching treatment with appropriate chemicals. However, the red shade... more
Process waters in deinking mills often feature a strong coloration, due to dyes and pigments released from the recovered paper. This can usually be remediated by pulp bleaching treatment with appropriate chemicals. However, the red shade (from rhodamine dye) is resistant to conventional bleaching treatments. This largely limits the use of deinked pulp in white paper grades. In this review, the available technologies for process water decolorization are discussed (chemical methods, physico-chemical methods and biological treatments). Ozonation of the process water appears to be the most promising technique for decolorization of process water in deinking mills. Other emerging technologies such as photo-catalytic treatment or mineralization by white-rot fungi (after adsorption on low-cost agricultural residues) should be considered as well.
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Production of lightweight coated paper (LWC) utilises more and more deinked pulp (DIP), for both economical and environmental reasons. A critical requirement on DIP quality for such grades is the cleanliness of the pulp. Indeed, the... more
Production of lightweight coated paper (LWC) utilises more and more deinked pulp (DIP), for both economical and environmental reasons. A critical requirement on DIP quality for such grades is the cleanliness of the pulp. Indeed, the coating layer may not fully cover specks in the base paper. The objective of this work was to determine the required specifications of the coating layer to produce LWC with DIP base paper. The specks masking phenomena by the coating layer was studied from both optical measurements on coated handsheets made from DIP, and computer simulations of specks contrast reduction. The impact of coating layer parameters (coat weight and optical properties), base paper parameters (grammage and optical properties) and specks nature (grammage and optical properties) on specks masking is studied.
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ABSTRACT With increasing utilisation rate of recycled raw material in newsprint and graphic paper grades, dirt specks contamination is becoming critical. Predicting sheet contamination from pulp contamination level is not straigthforward,... more
ABSTRACT With increasing utilisation rate of recycled raw material in newsprint and graphic paper grades, dirt specks contamination is becoming critical. Predicting sheet contamination from pulp contamination level is not straigthforward, as only a fraction of the specks are actually visible in a thick sheet. We propose a specks extinction model to predict the visible contamination in sheets of paper made of deinked pulp. The modelling makes use of the optical properties of the sheet material, and the size distribution of the specks population. The model can be used for multi-layer sheets as well. We demonstrate that it is possible to minimise visible specks contamination through a combination of stratified forming and deinked pulp fractionation.
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ABSTRACT The floc size distribution of pulp suspensions flowing in a flat channel is determined by image analysis (binary morphology). Among tested statistical distributions, the Weibull distribution is the best descriptor for floc size... more
ABSTRACT The floc size distribution of pulp suspensions flowing in a flat channel is determined by image analysis (binary morphology). Among tested statistical distributions, the Weibull distribution is the best descriptor for floc size distribution, over a wide range of papermaking conditions: hardwood/softwood mixtures with consistency ranging from 3.5 to 9.5 g/L and estimated shearing level ranging from 240 to 960 s-1. Results are analysed in terms of shape and scale factor of the model distribution and floc coverage in the image. Then, the corresponding sheet formation index is calculated, using the Farnood et al floc layering model at various inspection sizes. It is shown that the relationship between the flocculation index and the calculated sheet formation index is not expected to be linear.
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Résumé/Abstract Five retention systems were studied to compare increases in fiber flocculation. Fiber flocculation, filler retention, and drainage efficiency were measured in a pilot-scale flow loop with industrial-like furnishes. Fiber... more
Résumé/Abstract Five retention systems were studied to compare increases in fiber flocculation. Fiber flocculation, filler retention, and drainage efficiency were measured in a pilot-scale flow loop with industrial-like furnishes. Fiber flocculation was evaluated with an ...
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Pour ameliorer les proprietes optiques du papier et diminuer son prix de revient, le papetier a actuellement tendance a incorporer de plus en plus de charges minerales dans sa composition. Neanmoins, les agents de retention actuels ne se... more
Pour ameliorer les proprietes optiques du papier et diminuer son prix de revient, le papetier a actuellement tendance a incorporer de plus en plus de charges minerales dans sa composition. Neanmoins, les agents de retention actuels ne se revelent pas assez performants pour retenir les charges minerales dans la structure de la feuille lors de l'etape de filtration, ceci pour trois raisons essentielles. La premiere reside dans le fait qu'il est necessaire de disposer d'un systeme floculant selectivement les charges sur les fibres sans floculer les fibres entre elles, sous peine de detruire la formation de la feuille. La seconde raison est que les papetiers sont amenes a consommer le moins d'eau possible. Ceci se traduit par un enrichissement important des eaux de process en matieres minerales et organiques, enrichissement nuisible a la bonne efficacite des agents de retention classiques. Enfin, la troisieme raison est que les vitesses de production du papier augmentent...
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The invention relates to a deinking process comprising at least one step of separating the surface-active substances by dispersed air flotation, as well as the inking device suitable for implementing such a method.
Digital printing technologies are gaining more and more market shares. In a near future, several of these prints will end up in the recovered paper collection from households and offices, becoming part of the raw material to be recycled... more
Digital printing technologies are gaining more and more market shares. In a near future, several of these prints will end up in the recovered paper collection from households and offices, becoming part of the raw material to be recycled by papermakers. But the deinkability of several digital prints could turn out to become a threat for paper recy-cling systems of today some of these prints deink rather easily while some others lead to severe problems, which may endanger all the deinking process. Only a few of the digital printing machine suppliers joined the workshop on Digital Print Deinking recently held at CTP in Grenoble, where the results of recent research regarding the deinkability of digital prints were presented.The workshop was organised by CTP and supported by INGEDE who represents the major European deinkers, and the French Agency of Environment and Energy Management (ADEME). Problems are especially created when recycling waterbased, pigment based ink-jet inks more and m...
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High and uncontrolled surface active substances (SAS) concentrations in deinking line process waters strongly disturb flotation deinking. Indeed, their adsorption at air/water and ink/water interfaces stabilizes air bubbles and ink... more
High and uncontrolled surface active substances (SAS) concentrations in deinking line process waters strongly disturb flotation deinking. Indeed, their adsorption at air/water and ink/water interfaces stabilizes air bubbles and ink particles, reducing ink collection during flotation. In addition, foam stabilization promoted by SAS reduces froth drainage and consequently enhances suspended solids losses. All in all, selectivity of flotation is negatively affected by excessive SAS concentrations. Floating process water with adapted technology, a patented solution, is an efficient way to decrease SAS concentration and thereby recover flotation deinking selectivity. This concept was tested at industrial scale with success. First loop clear filtrates of a deinked pulp line (for newsprint production) were floated. At steady state, this treatment allows a 20% reduction of the SAS concentration in first loop process water. Evaluation of ink removal selectivity at pre-flotation and post-flot...
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Surfactants are largely present in papermaking/recycling processes. They are added intentionally or come with raw materials or process/functional additives. Once they have reached the process, they build-up in the circuits and, depending... more
Surfactants are largely present in papermaking/recycling processes. They are added intentionally or come with raw materials or process/functional additives. Once they have reached the process, they build-up in the circuits and, depending on their surface activity and concentration, they can have adverse effects on deinking and on the whole papermaking process, such as excessive frothing, depression of ink floatability, and paper sizing/retention difficulties. In this paper, the removal of apparent surface active chemicals (ASAASAASAC) is first evaluated in different flotation deinking mills through mass balances using surface tension measurements and a specific methodology. Mill data show that, in two-stage deinking lines, ASAASAASAC are slightly concentrated in the second stage, contributing to an increase in pulp frothing behavior, in flotation loss, and in some cases to a low ink removal efficiency. Trends observed in deinking mills are then interpreted using experimental data ob...
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The fraction of deinked pulp for coated paper production is continually increasing, with some mills using 100% deinked pulp for the base paper. The brightness of the coated paper made from deinked pulp may be reached through a combination... more
The fraction of deinked pulp for coated paper production is continually increasing, with some mills using 100% deinked pulp for the base paper. The brightness of the coated paper made from deinked pulp may be reached through a combination of more or less extensive deinking, compensated by appropriate coating, to optimize costs overall. The authors proposed general optimization methods combined with Kubelka-Munk multilayer calculations to find the most economical combination of deinking and coating process that would produce a coated paper made from DIP, at a given target brightness, while maintaining mechanical properties.