Study on Pulp Bleaching Hydrogen Peroxide Spray Bleaching of Unbleached Pulp and Bleached Pulp

Abstract

A laboratory scale study and experiments on the operating machine were made on bleaching many kinds of pulp by using Hydrogen Peroxide spray bleaching. Pulp sheet machine is quite conformable to Hydrogen Peroxide spray bleaching method. Basical conditions required for Hydrogen Peroxide bleaching process, such as low temperature, fairly long reaction period and high consistency were all satisfied with pulp sheet machine. Experiments have shown that much higher brightness is obtained by this method than with the equal rate of chemical cost. The presence of Hydrogen Peroxide residue in the finished pulp increased the brightness of the pulp while it was stored. However, this method was not available for stone groundwood pulp. Such as low temperature and long bleaching process time are not effective for stone groundwood pulp compared with the tower bleaching process. High charge of Hydrogen Peroxide is required for stone groundwood pulp, chemimechanical pulp and unbleached sulphite pulp compared with semibleached sulphite pulp and bleached sulphate pulp.