The kraft pulping process purpose is to individualize cellulosic fibers and remove lignin by white liquor, which main components are sodium hydroxide and sodium sulfide. This process is known to produce high strength papers, but causes odorous pollution and increases costs of the black liquor recovery system. The soda process is an alternative of pulp production without sulfur compounds. This study carried out a comparison between Soda-control pulp, Sodapulp with additives (AQ, Surfac. and AQ+Surfac.) and Kraft-control pulp. Anthraquinone made available a higher pulping yield for the Soda-process than that of the Kraft-control pulping, but also increased rejects content for the same kappa number. The surfactant did not produce good yield results as AQ did, but it kept shives content at low level. AQ decreases the alkali charge and residual in soda pulping, especially for AQS mixtures. No additive tested has got better viscosity results than those of Kraft-control pulp.

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Anthraquinone and surfactant effect on soda pulping

The purpose of this paper was to evaluate the effect of temperature, alkali charge, anthraquinone and ethanol additives in oxygen delignification for kraft pulp of Eucalyptus grandis vs. Eucalyptus urophylla with high kappa number and rejects content. In pulp production, the conventional kraft cooking was used with 13% alkaline charge, 25% sulfidity, in addition to H factor of 580. To reduce the rejects content, the pulp was subjected to two passages through the disc refiner. The oxygen delignification occurred in medium consistency (10%) and oxygen pressure of 5 kgf·cm-2, in addition to the delignification with the combination of four alkaline charges (15, 30, 45 and 60 kg·t-1) and four temperatures (80, 100, 120 and 140oC). The additives effect evaluation was made with 0.05% of anthraquinone and ethanol separately, just like the treatments with no additives as a reference. The brown pulp kappa number produced was 63.9 with 8.7% of rejects content. The comparison between the alkaline charge and temperature factors shows that the first is more influential in the oxygen delignification process. However, by increasing the temperature it was possible to reduce the kappa number with lower drop in selectivity. In addition, the temperature is the activating agent of the process reactions, given that for any alkaline charge applied, the residual alkali concentration decreases with the temperature increase. Also, there was no great drop in yield with the increased alkali charge and temperature. Simultaneously, the conversion of rejects into pulp ensured the yield maintenance. The anthraquinone addition showed no gains in the yield and in the kappa number results, but the process became more selective. The addition of ethanol showed positive results in terms of kappa number and rejects reduction, and also an increased yield. The total of solids generated had no significant influence of additives action.

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The effects of temperature, alkali charge and additives in the oxygen delignification in high kappa number eucalyptus pulp kraft

Evaluation of soda-antraquinone and magnesium base bisulfite pulping processes with bamboo The present study had as objective evaluates and to compare the soda-antraquinone and magnesium base bisulfite pulping processes for Bambusa vulgaris Schrad. with 2 years old originating from commercial plantings in Maranhão – Brazil seeking the production of bleachable and unbleachable cellulosic pulp grade's (kappa numbers 30±2 and 50±2 respectively). The raw material was characterized regarding the basic density, chemical composition and dimensions of fibers; for to the pulping processes was evaluated the total time of cooking, H factor, total yield, screened yield, rejects, load of chemical reagents and physicalmechanical properties of the pulps. The obtained results show that the raw material presented typical values for the species in subject in what says respect to the basic density, dimensions and morphologic indexes of the fibers and chemical composition. For the soda-antraquinone pulping process the certain levels of delignification (kappa numbers) were obtained with alkaline loads of 15 and 19% (NaOH base) respectively and a H factor of 1218; for the magnesium base bisulfite process the cellulosic pulps with the established levels of delignification were obtained with a fix load of chemical reagents 26% (SO2 base) and H factor of 1218 for pulps with kappa number 30±2 and 828 for pulps with kappa number 50±2; the necessary total time of cooking to the sodaantraquinone process to obtain the wanted cellulosic pulps are, on average, 3,82 time less when compared with the bisulfite process. Additionally the screened yields were 3 and 4,63 percent superior for the pulps with numbers kappa 30±2 and 50±2 respectively in the soda-antraquinone process. The physical-mechanical tests show the differences among the pulps in what says respect to the used pulping process as in the delignification level, being this last one a factor of differentiation of the products (paper) that can be obtained starting from the cellulosic pulps. Comparing the pulping processes as what concerns of physical-mechanical properties the superiority of the soda-antraquinone pulps is observed except in freeness and density parameters. The results obtained in this work show that for the production of cellulosic pulp from Bambusa vulgaris the soda-antraquinone process it is superior than the magnesium base bisulfite process as much in the aspects of engineering process (quantitative) as in the aspects related to the quality of the obtained pulp.

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Avaliação dos processos de polpação soda-antraquinona e bissulfito-base magnésio para bambu

Tese (doutorado) - Universidade de Sao Paulo, Escola Superior de Agricultura "Luiz de Queiroz", Piracicaba, 2015

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J.L Gomide

Papers

Antraquinona - um eficiente aditivo para a polpacao alcalina de madeira