Factors responsible for yield gains from Lo-Solids((R)) pulping of Eucalyptus species

Two investigations of the effects of the alkali profile during Lo-Solids (R ) cooking of eucalypt chips are described. One study pulped mixed Eucalyptu s species from New Zealand using liquors collected from a commercial digest er and compared the yields with those from conventional continuous and conv entional batch cooking. The second study pulped E. urophylla and E. leizhou from China under a range of alkali and temperature conditions. The studies confirm the importance of maintaining an optimum alkali profile during kra ft pulping of Eucalyptus species. Alkali concentration changes as small as 2 g/L during the early stages of pulping had a substantial effect on pulp y ield. When the alkali profile during Lo-Solids (R) simulations was optimise d for a particular species, yield gains of up to 4 percentage units compare d with batch or sub-optimal Lo-Solids (R) cooks were obtained. The yield ga in resulted from better retention of both cellulose and xylan due to the un ique alkali profile and low cooking temperature of these cooks.