Effect of sodium sulfite charge in NSSC pulping of E. Globulus

PEREIRA, M.; KORDSACHIA, O.; PATT, R.
Madera: Ciencia y Tecnología 13:2 (2011) 225-234.

DOI: 10.4067/S0718-221X2011000200010

Abstract

This paper presents experimental results on the effect of adding high doses of sodium sulphite (Na₂SO₃) to replace other sources of alkali, such asNa₂CO₃ or NaOH, in high-yield Neutral Semichemical Pulping (NSSC) process. Sodium sulfite (Na₂SO₃) was used as delignification agent in the chemical stage of eucalyptus globulus pulping. A 12” Bauer refiner was employed in the mechanical stage. Pulp yields ranged within 70-90% and, results show that physical and mechanical properties increased significantly as yields decreased. Moreover, the defibration energy consumption and beatings energy also showed a significant decrease. Those pulps featuring yields near 80%, obtained with high sodium sulfite loads, presented similar physical and mechanical properties as chemical pulps. At the largest sulfide dose used here, no significant increase in chemical consumption was observed, especially at high yields. This study shows that physical and chemical properties are enhanced by high hemicelluloses content, and process selectivity to remove lignin from the middle lamella, which leads to a fiber integrity and reduced mechanical stress.