Enhanced bleaching of wood pulp suspensions - contg. dissolved organic cpds. using addition first of chlorine di:oxide and chlorine then of chlorine alone

摘要

Bleaching of cellulosic fibrous material e.g. wood pulp, is claimed in an aq. suspension, using chlorine dioxide and chlorine. The chlorine dioxide constitutes 20-95% of the total available chlorine used. The suspension is subjected to a first bleaching step using an aq. soln. of chlorine dioxide and chlorine. Without an intermediate washing step the suspension is subjected to a second bleaching step using chlorine. Method is partic. useful for bleaching of wood pulp suspensions contg. dissolved organic material as a contaminant. By use of the sequential addn. of bleaching chemicals enhanced bleaching of the pulp is obtd. In practice, however, the method facilitates the use of less overall bleaching agent.