Green liquor and anthraquinone modified kraft pulping for improved manufacture of Linerboard

A study of modified kraft pulping for manufacture of Linerboard was carried out in the laboratory. In this study, the synergistic effect of green liquor and anthraquinone (AQ) pretreatment on pulp yield, kappa number and strength properties was evaluated. The process with 25% MGL/0.05% AQ along with 3% (A. A) kraft cooking can increase 2.7% Pulp yield and save 23% similar to 26% active alkali charge as compared to the conventional kraft cooking (9% A. A) at kappa number range of 107 similar to 110. The increase in yield with 25% GL pretreatment and with 25% MGL pretreatment is respectively 0.9% and 1.4% over the conventional kraft cooking (9% A. A). The physical strength of the modified kraft pulp is similar to conventional kraft pulp. The effect of sulfidity on the impact of AQ and MGL was investigated. The effectiveness of adding 0.05% AQ into 25% MGL along with low sulfidity kraft cook is better than with high sulfidity. The increase in yield with 25% MGL/0.05% AQ pretreatment along with 15% sulfidity kraft cook is 2% similar to 2.5% as compared to without AQ, while the increase in yield with 35% sulfidity is less than 1%.