Sodium borohydride assisted hydrogen peroxide bleaching process for mechanical pulps

Sodium borohydride can assist in improving the performance of peroxide bleaching of mechanical pulps. In this paper, we report the P-R process, in which a small amount of sodium borohydride, along with sodium silicate is added to the pulp for a pretreatment, followed by the addition of hydrogen peroxide. It has been demonstrated that the P-R process gives significantly higher brightness than the conventional peroxide process under otherwise the same conditions. The P-R process is of particular interest for mills to produce mechanical pulps of very high brightness.