Due to energy deficiency and high energy costs, there is a large interest in reducing energy consumption in production of mechanical pulp. Studies have shown that the energy required to liberate a single fiber from wood is very low.

The theoretical energy consumption for defibration is very small compared to that observed in mill operations. Thus there is a huge potential to reduce the energy consumption during refining.

Laboratory results have been very promising, suggesting that removal of extractives can be positive both for the energy consumption during refining to a given strength and for the final paper properties. In the present project these ideas will be further tested in pilot and full scale, and the mechanisms behind the promising results will be further investigated.

The basic idea of this project is to develop and support mill scale implementation of technology for achieving minimum 10% reduction in energy consumption for production of mechanical pulp while maintaining pulp quality and avoiding negative environmental impacts.

Wood extractives cause other severe production problems in addition to the negative effects on the fibre development during refining. As much as 7-40 tons native extractives, depending of raw material, enters the pulp mill every day, forming a colloidal dispersion in the process waters. The wood extractives in the process waters are causing severe runnability problems in later process stages of the mill.

Hence, the need for extractive handling strategies are a significant consequence of improved fibrillation and deresination of wood fibres. In the project the focus is directed towards extractives removal from chips and handling of the water in order to remove extractives from process water with flotation techniques.

The project is partly funded by the Research Council of Norway, and is a cooperation between partners from industry, institutes and universities.

R&D-partners:
  Paper and Fibre Research Institute (PFI). 
  Mid Sweden University, Sweden
  Norwegian University of Science and Technology

Contact Person: Lars Johansson