PROCESS FOR THE PRE-TREATMENT OF CHIPS

摘要

In view of the environment requirements of today it is essential to be able to delignify cellulose pulp to a low kappa number prior to the bleaching of the pulp. According to the invention, this is achieved in that the wood raw material in the form of chips is subjected to a pre-treatment with sulphur dioxide. According to the invention, this is carried out by using the sulphur dioxide at the treatment in gaseous state at an overpressure of 0-5 bar.