| PATENT ASSIGNEE'S COUNTRY | Finland |
| UPDATE | 01.00 |
| PATENT ASSIGNEE | Ahlstrom Machinery Corp |
| PATENT CLAIMS |
Method of processing cellulose pulp having a consistency 5-18% contg undesirable heavy metals without the use of Cl bleach chemicals - Cooking & delignifying comminuted cellulosic fibrous ma terial to produce cellulose pulp having a consistency 5-18% & kappa no. < 14 & contg heavy metals - Bleaching said pulp using a (ZT) stage having a Z-portion & T-portion, said (ZT) stage practiced by (i) if the pH of pulp is not within range 2-7, adjusting pH so that it is within eange 2-7; (ii) bleaching the pulp with O3 in Z-portion, & then removing gas from pulp, & then adding alkali & com plexing agent; & (iii) in the T-portion immediately after the degassing, alkali addition, & complexant addition following O3 bleaching in substep (ii), without intervening washing, removing undesirable heavy metals from pulp by using complexant in T-portion - Washing the pulp - Bleaching the pulp in at least one additional stage with pero xide alone |
| PATENT PHOTOCOPY | Available on request |
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