This work analyzed the effect of five tree plantation spacings for Eucalyptus dunnii species (3 m x 1 m; 3 m x 1.5 m; 3 m x 2 m; 3 m x 4 m and 3 m x 4 m). The aim was the production of a kraft-antraquinone pulp. Eucalyptus grandis and Eucalyptus saligna pulps obtained from commercially grown stands (at fixed 3 m x 2 m spacing) were also tested, as a comparison. The basic density and chemical characterization of the wood samples were analyzed through dichloromethane extractives, pentosans, lignin, 8% alkali solubility and ash content. The chips were submitted to typical kraft-antraquinone pulping conditions to reach 17 ± 1.5 kappa number (active alkali was varied from 18.5 to 21%, 8% sulphidity, 0.05% antraquinone, 4:1 wood: liquor ratio, 60 minutes to reach maximum temperature, 45 minutes at maximum temperature). The unbleached pulps were chemically and physically characterized (yield, rejects, kappa number, viscosity, brightness, 5% alkali solubility). The unbeaten pulps were submitted to refination in a Jökro mill under 35° SR, and with the beaten pulps, were submitted to physical-mechanical and optical testing (tensile strength, stretch, burst strength, tear strength, bulk, brightness, Gurley air resistance and Klemm capillary rise). The highest alkali consumption has occurred for the wood from the 3 m x 4 m tree spacing test, hence degrading the pulp. The woods from all tree spacing tests are viable for pulp production. The potential for cost reduction is overseen due to lower alkali and wood consumption, compared to Eucalyptus grandis and Eucalyptus saligna. The Eucalyptus dunnii pulp is a viable source for papermaking. Some potential problems such as encrustations and the closing of the circuit may arise due to the high values of extractives and ash contents during the industrial process.
Kraft pulp; pulp of quality; pulp of Eucalyptus