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Publication of NL117054BpublicationCriticalpatent/NL117054B/xx
D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
D21C3/00—Pulping cellulose-containing materials
D21C3/04—Pulping cellulose-containing materials with acids, acid salts or acid anhydrides
D21C3/06—Pulping cellulose-containing materials with acids, acid salts or acid anhydrides sulfur dioxide; sulfurous acid; bisulfites sulfites