Four stage alkaline peroxide mechanical pulpings

摘要

A process for applying chemicals, such as an alkaline peroxide pretreatment (1) to lignocellulosic material before chemical refining and at the primary refiner (3). The preferred embodiment comprises (i) preconditioning at temperatures below 95° C., especially below 80° C., (ii) limiting the time and/or temperature in the refiner, (iii) reaction quench to maintain temperatures below 80° C., and (iv) subsequent high consistency bleaching (4).