The effect of zeolite on value-added paper manufacturing

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schematic of the proposed process is presented in. Fig. 1. ... the other hand, traditional acidic papermaking .... Simplified schematic diagram of the proposed.
PA P E R P R O P E R T I E S

The effect of zeolite on value-added paper manufacturing

2002 JOHN S. BATES AWARD FOR BEST BRANCH PAPER

By E. Loranger and B. Chabot Abstract: Kaolin clay is extensively used in supercalendered papers. To improve paper optical properties, clay can be replaced by calcium carbonate fillers. However, it is dissolved in acidic environment generating free calcium ions and carbon dioxide in the white water system. Calcium ions react with wood materials promoting the formation of deposits which can affect paper machine operation and paper quality. We have used a zeolite to chelate free calcium ions in white water. The addition of zeolite had no detrimental effects on retention and drainage properties of pulp furnishes. Sheet properties were only slightly affected. RINTERS’ REQUIREMENTS for supercalendered (SC) papers are continuously increasing. They are specifically looking for higher optical and printability properties. Therefore, it is necessary to use higher quality fillers. Calcium carbonate is an interesting alternative to kaolin clay, which is normally used in those grades. Calcium carbonate has better optical properties at a very similar cost compared to clay. Calcium carbonate is mainly used in wood-free papermaking. However, it is not commonly used in wood-containing grades due to the high alkalinity of calcium carbonate suspension which promotes pulp darkening. On the other hand, traditional acidic papermaking conditions used in these grades are not suitable for calcium carbonate since it will completely dissolve carbonate filler, generating free calcium ions and carbon dioxide in white water systems [8]. The free calcium ions can then react with dissolved and colloidal substances found in mechanical pulps to form various precipitates that could affect paper machine runnability and paper quality [9]. To minimise both phenomena, the pH of the system must be maintained between 6.5 and 7.2. Therefore, a suitable pH control is essential. In order to run properly under these conditions, an acid tolerant precipitated calcium carbonate (AT-PCC) has been developed [7,4]. This technology is based on a buffer effect between a conjugated base (sodium hexametaphosphate) and a weak acid (phosphoric acid) [7]. This technonology is currently used at several mechanical pulp printing grades paper mills but its acceptance is still limited. White water management in multiple paper machines mills is another important issue. Excess white water from paper machines is used for pulp dilution at the machine and storage chests but also at the TMP pulp plant. The acid conditions prevailing there would completely dissolve calcium carbonate filler contained in the white water. This would increase the concentration of free calcium ions in the TMP pulp going to paper machines. It is therefore essential to remove the free calcium ions to limit their harmful effects. The chelation of free calcium ions has been used for a long time in the detergent industry. In

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the early 80’s, phosphates were successfully replaced by zeolites (type A) to control water hardness [10]. Zeolites have a high ion exchange capacity. They are used to remove free calcium ions that affect detergent’s performance in hard water. Zeolites are also widely used for water softening using ions exchange resins systems [11]. Brigatti et al. [3] have used a similar approach for waste water treatment. We propose to use a synthetic zeolite to remove free calcium ions in the excess white water sent to the TMP plant. A schematic of the proposed process is presented in Fig. 1. In addition, both PCC and zeolite show similar brightnesses (>96-98 ISO). Therefore, the added zeolite should compensate for PCC loss in the system. Ivanov et al. [5] have recently studied the effect of a zeolite as a filler in paper. The removal efficiency of free calcium ions by zeolites is well known [10,11]. Preliminary experiments with white water containing PCC have shown very good calcium ion exchange capacity for this type of zeolite. In this study, we will determine the impact of zeolite A on several processes involved during papermaking. Our objectives are to establish the influence of zeolite A on retention, drainage, and on optical and physical properties of papers.

MATERIALS AND METHODS Pulp furnish Pulps were provided by an Eastern Canadian paper mill. Table I presents the furnish compositions for all experiments. Retention trials To determine both calcium carbonate (PCC) and zeolite retentions, two typical retention programs were studied. The first program was a dual components system consisting of a coagulant (polydadmac) and a flocculant (cationic polyacrylamide). The second program (triple components) was consisting of a coagulant (polydadmac), a phenolic resin and a flocculant (polyethylene oxyde/cationic polyacrylamide). Both systems were provided by a chemical supplier. Filler first pass retention (FPR) was determined using the method described in a previous study [2]. The rotational speed of the stirrer was set at 1400 RPM, and a 60 mesh screen was used. Retention

E. LORANGER Centre de recherche en pâtes et papiers Université du Québec à Trois-Rivières Trois-Rivières, QC

B. CHABOT Centre de recherche en pâtes et papiers Université du Québec à Trois-Rivières Trois-Rivières, QC [email protected] 105:3 (2004) ❘❘❘

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FIG. 1. Simplified schematic diagram of the proposed papermaking process.

FIG. 2. Schematic diagram of the drainage device.

FIG. 3. First pass retention for zeolite and PCC with the dual components retention program.

FIG. 4. First pass retention for zeolite and PCC with the triple components retention program.

tests were carried out at 55°C. The pH of the suspension was set at 7. Drainage trials Drainage trials were carried out using the experimental set up shown in Fig. 2. The methodology was described by Fournier et al [1]. The device measures the vacuum vs time (drainage curves) during mat formation. Optical and physical properties of sheets Paper properties were determined using standard handsheets. The pH of the pulp suspension was adjusted to 7 with hydrochloric acid. A coagulant (polydadmac at 1 kg/ton) and a cationic polyacrylamide (0.5 kg/ton) were used for sheet making. Dried handsheets were calendered on a Beloit Wheeler laboratory calender. Calendering conditions are presented in Table II.

RESULTS AND DISCUSSION Fillers retention First pass retentions for PCC and zeolite fillers for both retention programs are shown in Figs. 3 and 4, respectively. Results indicate that zeolite and PCC retentions are very similar. It is suggested that zeolite particles retained in the sheet should compensate for the PCC lost at the TMP plant resulting from the white water acidification process. Drainage of fiber suspensions Drainage of fiber suspensions containing PCC and zeolite fillers are shown in Figs. 5 and 6, respectively. Polymeric systems used were the same as in retention tests. Results clearly show the effect of the retention polymer on drainage. Polymers increased the drainage capacity of the pulp suspension compared to trials

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TABLE I. Furnish compositions.

Bleached TMP TMP Kraft Fillers

Retention

Drainage

Handsheets

60 30 10 10

60 30 10 10

67 25 8 11

TABLE II. Calendering conditions. Calender speed Nip pressure Roll temperature Number of nips Nip configuration

0.135 m/s 52.5 kN/m 66°C 4 Hard roll – Soft roll

without polymer (blank), as shown by the time required to reach the minimum in absolute pressure. Drainage curves show that water removal from the pulp suspension (before mat formation) was faster when polymers were used, suggesting that water trapped within the fiber mat was more easily removed compared to trials without chemicals. The final level for the absolute pressure (plateau) is also an indication of the amount of water remaining in the mat. The closer the level to the atmospheric pressure (dotted line), the lower final water content in the mat. The amount of remaining water is closely related to the drainage resistance of the mat. It is thus clearly evident that drainage resistance was lower when polymers

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FIG. 5. Drainage of fiber suspensions containing PCC and zeolite for the dual components program.

FIG. 6. Drainage of fiber suspensions containing PCC and zeolite for the triple components program.

FIG. 7. Effect of PCC and zeolite on brightness and opacity.

FIG. 8. Effect of PCC and zeolite on gloss.

were used. Filler type did not have any influence on drainage properties of fiber suspensions as shown by the very similar curves obtained for PCC and zeolite filler containing furnishes. Optical and physical properties Optical and physical properties were determined on handsheets containing 11% PCC and/or zeolite fillers. The effect of PCC and zeolite on brightness and opacity is shown in Fig. 7. The effect on gloss is presented in Fig. 8. Brightness of zeolite containing sheets was slightly higher than PCC containing handsheets due to the higher brightness of the zeolite filler (98%) compared to PCC (96%). However, a significant reduction of the opacity was observed. Although handsheets were prepared with 11% zeolite, it is clear that a lower amount of zeolite will not affect as much optical properties of sheets containing mixtures of PCC and zeolite fillers. Figure 8 presents the effect of both fillers on gloss. Gloss was slightly higher for zeolite containing handsheets. This higher gloss can be attributed to a better calendering response of handsheets containing zeolite compared to handsheets containing PCC. This effect is probably related to significant differences in structural properties of zeolite and PCC particles.

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The effect of filler on PPS roughness and porosity of handsheets is shown in Fig. 9. Results show very similar roughness for handsheets containing PCC and zeolite. However, the porosity of handsheets containing zeolite filler was slightly higher. This could lead to higher ink penetration on a printing press. Figure 10 presents the effects of PCC and zeolite on breaking length and tear. Figure 11 shows the effects on burst. Results indicate that the zeolite filler reduced breaking length and tear compared to PCC, Fig. 10. However, burst was less affected by the zeolite. The reduction of strength properties with filler content is a well known phenomenon [6]. Fiber bounding interference increases with filler content. However, it seems that the zeolite filler has a higher detrimental effect on strength properties for handsheets at the same ash level. This can probably be attributed to the different structural morphology of zeolite compared to PCC.

clusions have been established. The retention of zeolite filler was very similar to PCC retention, for both commercial retention programs studied. Therefore, mixtures of PCC and zeolite fillers would not affect paper machine first pass retention. It is also concluded that the zeolite added could easily replace the PCC lost during white water acidification. Drainage properties of furnishes containing PCC or zeolite fillers were very similar. Therefore, the presence of zeolite particles would not affect drainage rate of the paper machine. The zeolite filler improved the brightness of calendered handsheets compared to PCC containing handsheets at the same ash level. However, opacity decreased significantly. PPS roughness was similar, while porosity of handsheets containing zeolite slightly decreased. Breaking length and tear were slightly lower for zeolite containing handsheets compared to PCC containing handsheets, while burst was increased.

CONCLUSIONS

ACKNOWLEDGEMENTS

We have studied the effects of zeolite addition in a fiber suspension. Comparisons were carried out with PCC filler. Although the goal of this study was not to fully replace PCC by zeolite, the following con-

The authors gratefully acknowledge the Natural Sciences and Engineering Research Council of Canada (NSERC) for their financial support. Thanks are also offered to LPM Technologies (retention 105:3 (2004) ❘❘❘

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FIG. 9. Effect of PCC and zeolite on PPS roughness and porosity.

FIG. 10. Effect of PCC and zeolite on breaking length and tear index.

polymers), Specialty Minerals (AT-PCC), PQ Corporation (Zeolite A) and Kruger Trois-Rivières (pulps) for providing various samples required for this work.

LITERATURE

FIG. 11. Effect of PCC and zeolite on burst.

1. FOURNIER, F., MORNEAU, D., CHABOT, B., DANEAULT, C., ARIAL, M., Rétention et drainage dans la fabrication du papier journal et annuaire, Congrès francophone du papier, ATPPC, Québec, pp.61-66 (2001). 2. BARIL, J., CHABOT, B., DANEAULT, C., MONTPLAISIR, D., ARHIRE, O., Comparaison de programmes de rétention pour la fabrication des papiers d’impression à base de pâtes mécaniques, Conférence technologique estivale 2000, ATPPC, Québec, pp. 21-27 (2000). 3. BRIGATTI, M.F., FRANCHINI, G., FRIGIERI, P., GARDINALI, L.M., POPPI, L., Treatment of Industrial Wastewater Using Zeolitite and Sepiolite, Natural Microporous Materials, Can. J. Chem. Eng., 77(1):163-168 (1999). 4. AIN, R.L., LALEG, M., Mill Experiences with AT Precipitated Calcium Carbonate (PCC) in Papers Containing Mechanical Pulp, Pulp & Paper Canada, 98(12):172-176 (1997). 5. IVANOV, K., GRUBER, E., SCHEMPP, W., KIROV, D., Possibilities of Using Zeolite as Filler and Carrier for Dyestuffs in Paper, Papier, 50(7/8):456-460 (1996). 6. GILL, R.A., HAGEMEYER, R.W., Fillers for Paper, Pulp and Paper Manufacture, Vol. 6: Stock Preparation (Hagemeyer, R. W., Manson, D. W., and Kocurek, M. J., ed.), Chap. 2: 19-38 (1992). 7. PASSARETTI, J.D., Acid-Stabilized Calcium Carbonate, Process for its Production and Method for its Use in the Manufacture of Acidic Paper, U. S. patent, 5156719, 20 October 1992. 8. EVANS, D.B., DRUMMOND, D.K., KOPPELMAN, M.H., PCC Fillers for Groundwood Papers, Tappi Papermakers Conf. Proc., pp. 321-330 (1991). 9. ALLEN, L.H., The Importance of pH in Controlling Metal-Soap Deposition, Tappi J., 71(1):61-64 (1988). 10. KURZENDORFER, C.P., LIPHARD, M., RYBINSKI, W., SCHWUGER, M.J., Sodium-Aluminium-Silicates in the Washing Process. Part. IX: Mode of Action of Zeolite A Additive Systems, Colloid & polymer Sci., 265:542-547 (1987). 11. JAMES, G.V., Water Treatment: A Guide to the Treatment of Water and Effluent Purification, 3rd edition, Edinburg, pp. 107-127 (1965).

Résumé: La glaise est grandement utilisée dans la fabrication des papiers surcalandrés. Celle-ci peut être remplacée par le carbonate de calcium pour améliorer la qualité de ces grades. Cependant, il se dissout en milieu acide pour produire des ions calcium et du gaz carbonique dans les eaux blanches. Ceux-ci peuvent réagir avec les composés du bois favorisant la formation de dépôts, ce qui peut affecter l’opération de la machine à papier et diminuer la qualité du papier produit. Nous avons utilisé une zéolite pour séquestrer les ions calcium libres dans les eaux blanches. L’incorporation de la zéolite n’a eu aucun effet négatif sur la rétention et le drainage. Les propriétés du papier n’ont été que partiellement affectées.

Reference: LORANGER, E., CHABOT, B., The effect of zeolite on value-added paper manufacturing. Pulp & Paper Canada 105(3): T53-56 (March, 2004). Paper presented at the 89th Annual Meeting in Montreal, QC, January 28-30 2003. Not to be reproduced without permission of PAPTAC. Manuscript received September 12, 2003. Revised manuscript approved for publication by the Review Panel September 16, 2003. Keywords: ZEOLITES, ION EXCHANGERS, CHELATING AGENTS, WHITE WATER, CALCIUM, RETENTION, DRAINAGE, PAPER PROPERTIES.

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