O2 Delig

DualOx® Enhanced Oxygen Delignification

GL&V is the world leader in oxygen delignification, having supplied over one hundred forty medium consistency oxygen delignification installations worwide.

Oxygen delignification has been done in several ways, high consistency, meduim consistency, one stage or two stage. The state of the art design today is the GL&V DUALOX® system which delignification with oxygen is primarily intended to facilitate your next stage of the process, i.e. bleaching. More effective delignification enables you to reduce the use of hazardous and expensive chemicals in the bleach plant.


Extended delignification feasible
More selective delignification
A simple design
Optimum conditions for the delignification process
Flexibility to adjust pressure and temperature in both reactors

Technical Information

The GL&V patented DUALOX® design with a short retention time pre-reactor followed by a booster pump and a second stage 60 minute reactor. This concept offers to enhance performance of a two stage system with a lower investment cost. The oxygen delignification system is of the GL&V patented DUALOX type in two-reactors. The process was designed using reaction kinetic equations, which were translated into a mill context. The equations state that the oxygen delignification process proceeds via two different phases, a very rapid initial phase and a slow final phase. As a consequence, the retention time is divided unequally between the two reactors, with a short retention time of 5-10 minutes designed in the first reactor and a longer retention time of 60 minutes in the second reactor.

The temperature in the first reactor is kept at a lower level to treat the pulp more mildly here in order to retain as high a final viscosity as possible. In the second reactor a higher temperature to ensure that the desired outgoing kappa number is reached. In this second kinetic phase the temperature does not affect the selectivity of the process meaning that the temperature level does not compromise the high final viscosity. The pressure is kept at a high level throughout the whole of the system in order to make the oxygen dissolve easily stay in solution for as long as possible. In order to maintain a high pressure in the second reactor apart from a mixer also a booster-pump is placed between the two reactors. This way the pressure is increased to a high level again.

The DUALOX system is a compact two-reactor oxygen delignification system setting a standard for the state-of-the-art technology. It allows a high delignification degree to go hand in hand with a good selectivity.

Customer Testimonials

  • I always know that when I contact the team at Bancroft Western, I will get the information I need in a timely fashion. They are extremely knowledgeable about the products they represent and truly understand the concept of customer service. A great company to deal with.
    - W.J. (Bill) Davidson, Senior Buyer
    Canfor Pulp Limited Partnership
  • I have worked with Bancroft Western and Al Parsons for the last 6 years with new mechanical equipment and refurbishing of existing equipment. I have been completely satisfied with the quality of work, timelines, knowledge, and the fast efficient service we at Zellstoff Celgar have received.
    - Murray Sloan, Mechanical Rebuild Specialist, Zellstoff Celgar
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