Operating Results of New Twindrum Pulping Concept at SP Newsprint Co., Newberg, Oregon, 2002 Fall Technical Conference

SP Newsprint placed an order with VOITH PAPER to replace their wash deinking plant with a one loop deinking line for a design accept production of 550 BDMTPD.

The deinking plant improvement includes the first installation worldwide where the TwinDrum™ drum pulper concept is used to disintegrate ONP/ OMG furnish for production of premium newsprint paper grades. The deinking plant furthermore includes high density cleaning, coarse screening, EcoCell flotation, fine screening using C-bar screening technology, wash deinking for flexo ink removal and final thickening with screw presses before storage.

The usable fiber loss with the drum pulper is close to zero, while OCC fiber flakes are being rejected. The ink detachment (ID) is 92% over a pulping consistency range of 19-33% determined according to INGEDE (Internationale Forschungsgemeinschaft Deinking-Technik e.V.). The maximum ID achievable was 94% measured on sorting drum accept pulp, which was also lab disintegrated. The higher ID after lab disintegration, relative to the sorting drum accept pulp, indicates that the remaining ink after pulping is not irreversibly ”smeared” onto the fiber surface.

The fine screening sticky removal efficiency is 92% with a total plant removal efficiency of 95%, which leads to 150 mm2/ kg of stickies in the final pulp. Comparing the plant sticky removal efficiency with seventeen North American paper mills reveals that Newberg lies substantially above the nationwide average, which is 65%. The brightness gained during the deinking process is 13.2 points. The final pulp brightness including hydrosulphite bleaching is 61%. The ERIC value of the final pulp is below 250 ppm.

With the new drum pulping concept, the papermaker has an attractive alternative to existing pulping systems. The concept distinguishes itself from other systems with high operating reliability at pulping consistencies between 19- 33%. The sorting drum reject is virtually free of usable fiber. Brown fiber originating from OCC grades is effectively rejected. The specific power consumption is 15 kWh/BDMT.