Patent ID: 8257550

Claim:
A method for bleaching an oxygen delignified and washed pulp having a consistency of between 8 and 20% comprising: (i) subjecting said pulp to a first chlorine dioxide bleaching step at a temperature of between about 80 to 95° C. and a pH of between about 2 and 4 to obtain a bleached pulp; (ii) washing said bleached pulp to obtain a washed pulp; (iii) subjecting said washed pulp at a consistency of between 8 and 20% to an alkaline extraction step to obtain an alkali-containing pulp; (iv) adding chlorine dioxide to said alkali-containing pulp and adjusting the pH to obtain a second chlorine dioxide bleaching step, wherein step (iv) is performed directly after step (iii) without any intermediate washing step; and (v) subjecting said pulp to a peroxide treatment step directly after or after an intermediate wash following said second chlorine dioxide bleaching step.