Abstract: A process for adjusting the pH of a cellulosic pulp in a pulp and/or paper mill, and to the production of pulp, paper or board from so treated cellulosic pulp is disclosed. In the process, the pH of an alkaline cellulosic pulp is adjusted at least twice with carbon dioxide before a neutral treatment and at least once with a strong acid before a subsequent acidic treatment. Between the first and the second carbon dioxide induced pH adjustment there is provided a (bi)carbonate removal step, which reduces the buffering capacity of the pulp. Also provided for is the use of (bi)carbonate removal for reducing the consumption of acid in the treatment of a cellulosic pulp.

Abstract: The invention relates to a process for the deresination of pulp as well as to the use of carbon dioxide or a (bi)carbonate compound for the deresination of pulp. The process concerns the removal of wood extractives or resin from an aqueous pulp suspension in an alkaline process stage of the pulping process, such as an oxygen delignification stage, at a pH above 10. Carbonate ions are provided in the pulp at the high pH for solubilizing a significant part of the wood extractives in the pulp. The alkaline pulp is dewatered to remove solubilized extractives and for providing a deresinated pulp.

Abstract: A method of treating cellulose pulp which is subjected to an oxygen-delignification stage (3), a washing stage (4), an ozone-bleaching stage (1) and a further bleaching stage, for instance a peroxide-bleaching stage (7). A gas mixture of oxygen and ozone is delivered to the ozone-bleaching stage (1). The used gas mixture is regenerated, i.e. freed from carbon dioxide, and returned to the oxygen-delignification stage (3) and/or to a bleaching stage (7).