Alkaline cooking, washing and delignification of cellulose shavings - for paper pulp in vertical three zone reactor (SW 27.12.77)

摘要

A process for the alkaline cooking and delignification of cellulosic materials using a vertical reactor under pressure comprising in order an alkaline cooking zone, a washing zone and a delignification zone with displacement of the liquor. The cellulose material in the form of shavings is introduced into the 1st zone with an alkaline liquor and contacted for a sufficient time. The cooked cellulosic material is then washed. An aq. alkaline medium in which oxygen has previously been dissolved is introduced into the delignification zone and the washed cellulosic material is contacted with this liquor. The liquor in the delignification zone is partly continuously displaced by continuously introducing fresh oxygen contg. liquor. The delignified cellulose material is then evacuated from the reactor. The process is used to make pulp for paper-making. The process has the advantage of reduced water pollution and nauseating smell. It gives a more efficient controlled delignification. It can be carried out in a single reactor giving a pulp of kappa value 7-10 without separate bleaching.