New Pulping Strategy for DIP in Tissue Mills, 2005 Engineering, Pulping & Environmental Conference

Actual deinking processes use more and more complex processes that often include a secondary deinking loop and sometimes a third one, which induce an increase in production costs (chemical, energy, investment, maintenance) and an increase in losses (sludge). A rationalisation of the deinking process is required to reduce this increase in complexity. As the pulper is the first step of regeneration of secondary fibres, it should be considered as the key point of the rationalisation of the overall process. For this reason, rationalisation of the pulping process should therefore be proposed in order to find the best compromise allowing the quality improvement of tissue paper based on recycled fibres. In a first part, the rationalisation taking into account optical properties and stickies contamination is proposed, based on analyses of pulping stage in a tissue mill and pilot plant trials. A reduction in pulping time is then suggested based on reduction in stickies fragmentation, energy saving and deinking line production increase. However, this solution induces some drawbacks such as a reduction in ink detachment and an increase in speck contamination. A solution is then proposed and the results coming from pilot trials are presented in comparison to conventional process.