A hot chlorine dioxide process for bleaching of hardwood kraft pulps. It offers many advantages compared to a conventional first dioxide stages.
The DualD™ technology is positioned in the first D-stage in the bleach plant to remove the Hexenuronic acid (HexA) in pulp that shows up as kappa number in pulp. If not removed earlier on in the bleaching process, HexA consumes oxidants such as chlorine dioxide or hydrogen peroxide that results in high bleaching chemical consumptions. The process was developed a few years ago and has become common in many bleach plants especially for production of hardwood and specifically eucalyptus pulps.
Benefits compared to conventional D0 stage, the DualD™ concept is more cost efficient with respect to:
- Reduced total chlorine dioxide consumption
- Reduced brightness reversion
- Increased brightness ceiling
- Studies indicate that a reduction of 20-30% can be expected when replacing a conventional D0-stage with a DualD™ stage.