Two-stage oxygen delignification system at Veracel Celulose S.A. mill, Brazil

ANDRITZ oxygen delignification systems

Environmentally sound solutions for chemical pulp bleaching

The combination of intelligent reactor designs, advanced mixing technology, and innovations in process control brought to the industry by ANDRITZ enables pulp producers to have oxygen delignification systems with superior levels of kappa reduction without negatively impacting chemical pulp quality.

Two-stage oxygen delignification system at Veracel Celulose S.A. mill, Brazil


A reduced environmental load while maintaining pulp quality

The use of oxygen-based systems to remove lignin from pulp significantly reduces the biological load (AOX, COD, and BOD) in a pulp mill compared to systems utilizing chlorine. The trade-off in using oxygen delignification in the past has been an increase in fiber damage, and a resulting loss in fiber strength. ANDRITZ has developed and enhanced its oxygen delignification technology to not only efficiently reduce the environmental load, but also maintain pulp quality.

Single- or two-stage reactor systems

ANDRITZ technology provides highly efficient oxygen delignification using one or two reactors, depending upon process requirements. The reactors are pressurized and operate in the medium consistency range.

 The ANDRITZ process ensures a significant reduction in kappa with low variation (uniform pulp quality). In the ANDRITZ oxygen delignification process, screening is performed after the oxygen stage, prior to washing and bleaching, to increase the wood yield since a considerable fraction of shives is converted into good pulp.

Processes and technologies available from ANDRITZ

  • Pressurized oxygen delignification reactors: one or two stages depending on process requirements
  • Fluidizing blow tube design: less volume, smaller footprint, smoother operation
  • AMix AC chemical mixer
  • DD-Washer drum displacer washer
  • COMPACT PRESS wash press and GasFree Filter vacuum drum washer for some special applications

ANDRITZ also supplies Dualmix chemical mixers and DualOx reactor technology for upgrades where there is an existing Dualmix and DualOx installed base if the existing technology is not to be replaced entirely.

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