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CONFERENCE: 6th Research Forum on Recycling

It seemed a natural coincidence: as the colours of the trees began to blaze in their autumn cycle, a conference on recycling was taking place in the Eastern Townships. Over a hundred delegates from ac...


December 1, 2001
By Pulp & Paper Canada

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It seemed a natural coincidence: as the colours of the trees began to blaze in their autumn cycle, a conference on recycling was taking place in the Eastern Townships. Over a hundred delegates from academia and industry gathered at the Manoir des Sables near Magog, October 1-4, to exchange ideas and the results of research and confirmation in a forum sponsored by the Pulp and Paper Technical Association of Canada (PAPTAC).

Conference chairman Gilles Dorris welcomed delegates this year by saying that, with fewer scientists specializing in recycling, fewer papers were being written on the subject. This meant that the conference committee had to look longer and harder to organize a forum that had an in-depth sampling of current recycling expertise. To further strengthen the scientific and technical content of the conference, four well-known researchers and practitioners from various recycling centres around the world joined the Program Committee, giving it an international flavour and expertise. The mix of research scientists and academics with the industry practitioners made for a diverse crowd, good information, new findings, as well as being a good size to encourage discussions. The objective of the Forum was to provide research engineers and scientists the opportunity to discuss the underlying fundamentals of recycling processes and how they impact recycling operations, and to identify future research needs of the recycling community.

Participants heard the latest in recycling research done world-wide, discussed and debated technical and operating issues, and toured one of two recycling facilities, the Kruger Bromptonville mill and the Cascades Kingsey Falls mill. It was a good balance between theory and practice, resulting in an efficient way for the academics to understand the problems faced by the industry. Question periods were not cross-examinations, but often helped the speakers with good suggestions for further research.

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Over the past five conferences, many theories had been explored and many new processes had been employed successfully. Experiments continue to test and retest these theories in a multitude of ways and some of the papers presented were further developments of previous research.

Changes over the past several years include the more frequent mention of ERIC, the measurement of Effective Residual Ink Concentration. And, indeed, the first paper introduced ERIC to this conference and it continued to be woven throughout the presentations of the day. Another concept that was continued from previous research was the “summer effect” (an increased amount of small ink particles attached to the fibres starting in mid-July and lasting throughout August).

Through in depth studies, theories change and sometimes even change back. As an example, in one of the first conferences a question was asked about why fibres float and the results of that year pinpointed the cause on an affinity between the fibres and oxygen. Through the years, other theories were postulated, noting that the fibres float because of entrainment. The latest theory postulates that it is due to both. Conflicting results from various trials were blamed on the difference between industry practice and academic research. Some numbers would be more comfortable to industry but university studies sometimes concentrate on specific phenomenon.

As always, in between papers and presentations, delegates met for informal discussions of their interests and were further entertained by several organized get-togethers, including a conference reception and banquet on Tuesday evening at the Cep d’Argent Winery. At the banquet, the entertainment took the form of an incredible routine by self-styled comedic “mentalist” Gary Kurtz, who mystified the audience through incredible feats of mind-over-matter. Engineers and scientists tried to find rational explanations for the amazing performance but came away with only a wry acknowledgment of how useful those talents would be in their industry.

Surveying mill operations

The first paper delved right into a comparative benchmarking study of the deinking performance of the DIP line in Norske Skog’s Skogn mill with a similar line in central Europe. Partly based on results obtained in Free Ink(r) Europe 2000, Anders Hestner (Eka Chemicals AB) and Aanon Rring (Norske Skog Research) studied how the physiochemical conditions, which included a high dosage of alkali, during pulping played a significant role when trying to obtain a good deinking performance.

Over the last seven years of mill surveys, R. Daniel Haynes (Akzo Nobel, Eka Chemicals) compiled the results from the deinking performance and presented an accumulation of data to be used to establish an industry benchmark.

Ink detachment and repulping

Frantisek Ruzinsky and Chad P.J. Bennington (Pulp & Paper Centre, UBC) showed that ink-fibre attachment force for aged magazines, advertisement inserts and xerography printed paper is significantly higher that that of newsprint grades. Various methods were explored to reduce the significant quantity of recalcitrant ink, including the adjustment of process temperature, addition of chemicals, increasing shear forces and extending the repulping time without redeposition of the ink.

The effect of initial repulping pH on the deflaking rate of recovered papers was studied by Franois Brouillette and Claude Daneault (Pulp & Paper Research Centre, UduQ, Trois-Rivires), using a helical repulper. They also established the effect of coating layers and mineral fillers on the deflaking rate, taking into consideration the volume concentration and viscosity of pulp.

Benjamin Fabry, Bruno Carr and Pierre Crmon (Centre Technique du Papier (CTP), Grenoble) investigated the different pulping parameters (mechanical, thermal and chemical) in terms of defibering, ink fragmentation, ink detachment, ink redeposition, speck contamination and also in terms of final pulp quality after flotation.

Jim Merza and R. Daniel Haynes (Akzo Nobel, Eka Chemicals) focused on the dinking or ink release properties of two pulping processes: batch and drum, and compared the two types with respect to season, deinking agent type and pulping time.

Separation unit operations

Strker T. Moe (Norwegian University of Science and Technology) and Aanon Rring (Norske Skog Research) concluded that the single most important parameter affecting the Norske Skog Skogn DIP mill was water hardness. Substituting emulsion by soap in the pulper had apparently no negative impact on flotation parameters.

Since bubble size as a parameter to characterize gas dispersion, C.O. Gmez, H. Hernndez, J. Torrealba and J.A. Finch (Dept. of Mining and Metallurgical Engineering, McGill University) tested sensors that had been developed for the minerals industry with a view to rating their performance for paper pulps.

Continuing the study of gas dispersion parameters, H. Herndez, C.O. Gmez and J. A. Finch used deinking in a flotation column to test the relationship between the collection zone flotation rate constant and the bubble surface area flux.

Frantisek Ruzinsky, Min-Hua Wang and Chad P.J. Bennington (Dept. of Chemical and Biological Engineering and Paprican, P&P Centre, U of BC) characterized dispersion in newsprint deinking operations following the refining theory of Miles and May. Ink detachment increased as the intensity of bar impacts increased.

To avoid changing the screening system configuration in a mill, Samuel Schabel (Voith Paper Fiber Systems) presented a tool for mathematical simulation of screens and screening systems in order to demonstrate the effects of screening system configuration parameters and screen operating.

Contaminants and stickies

C. Castro, G. Dorris (Paprican) F. Brouillette and C. Daneault (Centre de Recherche en Ptes et Papiers, UduQ Trois-Rivires) proposed a new thermogravimetric technique for the determination of synthetic polymers in pulp, paper, process, water and deposits.

Bangji Cao and Oliver Heise (Voith Paper) analyzed contaminants in OCC to promote the understanding of their respective impact on paperboar
d quality and proposed three quantitative methods to determine the contaminant level in OCC pulp.

Christiane Ackermann, Hans-Joachim Putz and Lothar Gttsching (Institute of Paper Science and Technology, Darmstadt University of Technology) established a test method to evaluate the behavior of recycling benign adhesive applications.

Marianne Lenes, Ingvild Andersen and Anne Marie Reitan (Norwegian P&P Research Institute) investigated the formation of stickies in process water using a stickies deposition tester to characterize the potential of the process water to produce secondary following the addition of the cationic polyelectrolyte polyethylene imine (PEI).

Thierry Delagoutte (Centre Technique du Papier), Ian J. McLennan and Steven Bloembergen (EcoSynthetix) developed a fluorescent labeling method to track PSA contaminants in laboratory paper recycling.

Jorge L. Yordan, Jordan Kortmeyer (Luzenac America) Ismail Yildirim and Roe-Hoan Yoon (Virginia Polytechnic Institute and State University) studied the interaction between four types of microstickies (adhesive, hot melt, wax and toner ink) and three minerals (talc, bentonite and ground calcium carbonate). The results explained why talc is the most effective mineral for removing the variety of microstickies found in recycled pulps.

Process watersystems

Christoph Mller-Mederer, Hans-Joachim Putz and Lothar Gttsching (Institute of Paper Science and Technology, Darmstadt University of Technology) studied red discolouration in deinked pulp under the influence of seven process and chemical conditions during recycled fibre processing simulated on a lab scale.

Theodore M. Garver (Aquantix, Alberta Research Council) studied the improvement of deinked pulp furnish using on-line analysis and control of dissolved substances.

John Mosbye (Norwegian P&P Research Institute), Margareth Holte (NTNU, Dept. of Chemical Engineering), Janne Laine (Swedish P&P Institute) and Strker Moe (NTNU Dept. of Chemical Engineering) studied the adsorption of model colloidal extractives to different types of fines, using chips from Norway spruce refined in a pilot refiner.

Yuxia Ben, Gilles Dorris, Geoff Hill and John Allen (Paprican) benchmarked the performance of dissolved air flotation (DAF) units for removal of contaminants from deinking process water in two Canadian deinking plants. From measurements of suspended, dissolved and colloidal substances in deinking process water, they established that, with bentonite/PAM chemistry, DAF units are very effective for removal of suspended solids; however, microflotation of DCS is negligible.

E. Savu, S. Sarrailh (Dpartement de gnie chimique, cole Polytecnique, Montral), F. Marchal ( Laboratoire d’analyse et de synthse des systmes chimiques, Universit de Lige) et J. Paris (Dpartement de gnie chimique, cole Polytecnique, Montral) ont developp des stratgies de rduction de la consommation d’eau frache dans un atelier de dsencrage de vieux papiers journauz par la rutilization de l’eau blanch excdentaire d’un papier voisin.

Bleaching

Goda Rangamannar (Rohm and Haas), Yves Dionne (Bowater P&P Canada) and Robert Bellemare (Rohm and Haas) investigated the effect of residual ink on hydrosulphite bleaching for Bowater Gatineau. The goal of the study was to understand the effect of residual ink on bleachability of deinked pulps using borohydride generated hydrosuphite process (BGH).

The objective of the study by C. Leduc, A.M. Launois, B. Chabot, C. Daneault (Centre de recherche en ptes et papiers, UduQ Trois Rivires) was to determine the feasibility of using activated peroxide and sodium perborate at the pulping stage of the deinking process of old papers and the impact on the environment.

Luc Lapierre, Diane Pitre and Jean Bouchard (Paprican) determined that the cause of the poor response of DIP fines to bleaching agents could be attributed to two factors coming from external contamination: high effective residual ink and high level of transition metals, specifically iron.

Mill operation and uses

L. Ferguson, R. Shaw, R. DeBerry and C. Henriksson (American Fiber Resources) asked, and answered, whether deinked pulp dare compete with virgin pulp. They stated that high quality deinked pulp is finding increased acceptance as a hardwood substitute.

Corinne Le Ny, Marko Haveri (UPM_Kymmene, R&D DIP Center) and Heikki Pakarinen (UPM-Kymmene, Valkeakoski Research Center) presented an investigation of the impact of RCF raw materials quality on deinking performance pilot and mill scale study.

Kate Cathie and Graham Appleby (M-real New Thames) studied the effect of recycled fibre processing conditions compared to virgin fibre on paper machine performance.

As a solution to the deinking problems for small mills, Steve Kittelberger (Steve Kittelberger Consultants) and Guerino Sacripante (Xerox Research Centre of Canada) studied a new deinking process based on a toner reformulation with toner binder resin with weak acidic properties.

P. Sterner and L. Ferguson (American Fiber Resources) demonstrated the beneficial re-use of deinked sludge, benefiting the environment through land reclamation, energy generation and other possible products.

Mill operations panel

Before the last session of presentations, time was set aside for one of the favourite sections of the recycling forum — the roundtable discussion. “Not only is it interesting,” as Roger Hare said, “but we might even learn something.”

Dan Orlando, mill manager for Newstech Recycling, stated that ERIC meters have been very important for the industry, with a “very tangible” benefit, since a lot of money has been saved through more precise measurement of results and he believed that such benefits would continue.

“The approach changed a lot with all the information that has become available,” said Yves Deraiche, plant manager, adding that he thought improvement of equipment was the greatest gain.

Erwin Krauthauf, former mill manager for Haindl Papier GmbH, agreed, stating that this was the time that information between academics and industry people was shared as to which developments in technology meshed with the needs of production.

He also spoke of changing flexo-inks. “The more you get into recycling, the more you have to talk to ink-producers, magazine and adhesive manufacturers. It’s necessary to seek the cooperation of the various participants in the paper chain.”

Roger Hare issued a challenge to de-trashing systems for recycled fibres. Gilles Dorris asked what would the panel like to see in chemistry. One of his suggestions was to lower amounts of salts used in the various processes, due to high environmental pressures. He recommended thinking outside-of-the box for a solution to make this work.

Chad P.J. Bennington asked if there was a method fir fines extraction so that there can be more concentration where it is needed before it is recombined.

Despite the narrow and specific interests of many of the participants, there was a generous give and take between the presenters and the audience. Occasionally when the presenter could not answer a specific question, a member of the audience would volunteer with an answer or a suggestion of where to look for it.

Those attending seemed quite satisfied. “It was great teamwork,” said Chad P.J. Bennington, program chairman. “It met all my expectations.”

Steve Kittelberger, (Steve Kittelberger Consultants) specialist in both the deinking and recycling fields, was one of those satisfied with information gleaned from both the delegates and participants. It confirmed his impression that, as he said, “This conference has always been mentioned as one of the best in the business.”

R. Daniel Haynes (Akzo Nobel Eka Chemicals) who had developed the Free Ink project, called the conference “the best ever”. “The level of papers was very good,” he said, “and people asked some very hard questions. It was good mix of mill people and academia.”

The true success of this forum will be seen through the implementation of the technology and programs discussed. The nuts-and-bolts type of questions and answers seemed to indicate that many of the industry peop
le were preparing to utilize knowledge gleaned at this conference.

Which would, in turn, generate questions and discussions at the next research forum on recycling.