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ANDRITZ kraft pulp refining

State-of-the-art solutions for sack paper applications

Blowline refining

Blowline refining defibrates chips after the continuous digester. Modern chemical pulping systems for linerboard use continuous digesters and diffusion washers with no screening systems at all. The cook is completed at high kappa (>100) and yields over 60%, which is achieved by ANDRITZ blowline refining combined with deshive refining. This combination results in low installed cost, low operational costs, and high-strength, low-shive pulp.

Deshive refining

Deshive refining is atmospheric refining that follows the washing step in kraft or semi-chemical pulping. The refiner is fed at medium consistency with a conveyor or MC pump. The objective is to reduce the shives in excess of 70% (Pulmac 2.5 mm, 0.010”) from a higher yield cook. Deshive refining can be used on batch or continuous digester systems. The deshive refiner is an atmospheric HC refiner with gravity discharge.

Benefits of deshive refining

  • Efficient shive reduction
  • High fiber length and high tear index preserved due to low intensity refining
  • Improved bonding strength, Tensile Energy Absorption (TEA), concora, and ring crush results
  • Very little freeness reduction
  • Optimized pulp washing and minimum chemical losses due to split between blowline refining and deshive refining

Sack paper refining

Higher Tensile Energy Absorption (TEA) at higher air permeability is a key quality target for sack paper producers. ANDRITZ HC sack kraft refining technology achieves these targets through:

  • High refining consistency with the ANDRITZ Twin Wire Press
  • Even refiner feeding with the unique ANDRITZ shredder
  • Large refining area provided by the ANDRITZ 60” refiner

Benefits of sack paper refining

  • High refining consistency, ideally 35%+, leads to better pulp quality
  • Higher Tensile Energy Absorption (TEA)
  • Higher air permeability
  • Higher production rate on the paper machine due to higher pulp drainability (less refining at the required TEA and air permeability)

A unique shredder following the Twin Wire Press ensures uniform feeding of the refiner and a constant refiner load. This helps achieve the pulp strength targets at a higher freeness level.

A large area inside the refiner allows better fibrillation of fibers and leads to better stretch. It also ensures lower refining intensity because of a wider plate gap. This contributes to less bar-to-fiber contacts and more fibrillation which results in:

  • Higher tear and tensile strength
  • Better shrinking/stretch potential
  • Superior tensile energy absorption values
Twin Wire Press

Twin Wire Press




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