Oxygen-alkaline pulping is a sulphur-free chemical pulping process, which has a potential to replace the kraft process as an environmentally more viable alternative. However, there are some drawbacks to the process, which have so far prevented it from commercialization. The penetration of oxygen into the structure of wood chips and rather severe degradation of carbohydrates are the main problems that result in high reject contents and low pulp strengths. In this study, wood chips, after presoaking in a 0.2% solution of alkali, were mechanically treated in a compression screw feeder with the aim to facilitate the penetration of oxygen. Mechanically pretreated wood chips produced oxygen alkali pulps with screened yields that were almost 13% higher than those without mechanical treatment. At the same time, the total yields of both pulps were comparable. To improve the strength of the oxygen-alkaline pulps, the pH of the pulping liquor was kept constant between 7 and 8 throughout the pulping process. This resulted in a pulp that has a viscosity 3 times greater than that of the control oxygen-alkaline cook, thus indicating an improvement in strength properties.

Berk, Dimitrios (Supervisor)

Kubes, George (Supervisor)