Challenge of Bringing Bleaching Results from Lab to Full Scale, 1997 Recycling Symposium Proceedings

All recycled pulps are unique due to several factors such as the mix of waste paper, collection area, sorting etc. Each mill is also unique depending on process design, chemicals in use and the quality requirements for the end product. Due to the above mentioned factors, each mill has to be treated as an individual when trying to find the best solution for reaching their targets on product quality, cost efficiency and environmental impact. Lab bleaching and pilot plant trials are conducted under strictly controlled conditions which are not always achievable in mill scale. A more holistic view is then needed to cope with the set mill requirements. Fluctuations in the raw material quality as well as in the ink removal efficiency will greatly influence the observed post bleaching brightness. Generally, it is possible to reduce the light absorption arising from the fibres, but this effect is often shaded by residual ink and dyes. Light absorption caused by residual ink and dyes often limits the bleachability of a pulp.