OXYGEN DELIGNIFICATION OF PULP

摘要

A medium consistency oxygen delignification process and apparatus, utilizing one or more substantially horizontal agitated tubular reaction zones (10). The use of rotary screws or paddles (24) in the reaction zone or zones provides the agitation required to enable good mixing of oxygen with the medium consistency pulp and alkaline chemicals as well as the control of the pulp retention time in each reaction zone (10). In one embodiment of the invention, pulp is transported from the cooking stage through line (54) to screens (56) where oversize slivers, shivers, knots and other impurities are removed. The accepted pulp passes through line (58) into pulp washer (50) while the rejected material is sent to refiner (52) for further fiberization before being recombined with the main pulp stream through line (60). This combined pulp stream is then washed and oxygen-delignified as described above to yield a bleachable grade pulp.