Chlorine di:oxide bleaching process for paper pulp

摘要

A process for bleaching paper pulp using a chlorine dioxide bleaching step has this step separated into the following three stages: (1) gaseous chlorine dioxide is added to the pulp to carry out bleaching at an acidic pH and a pulp consistency of 25-45 ; (2) the pre-bleached pulp is diluted to a consistency of 8-16 % and rendered alkaline to a pH of at least 6; and (3) the alkaline pulp is acidified to give an acidic pH and then bleached at 8-16 % consistency with chlorine dioxide.