Energy consumption lowered by 10% with a corresponding increase in production, fewer shives, higher brightness and less demand for reinforcement pulp and a total savings amount to some USD 7 millions per year.

The reduction of energy consumption in mechanical pulping has long been an important field of research at PFI. In 2002, a research project was started jointly with Norske Skog. Plans existed for a rebuilding of the Norske skog Pisa Mill in Brazil.

Earlier trials had shown that the strength target could not be reached using native Loblolly pine as the single raw material. The mill had previously had lower strength targets and had also been allowed to mix in other raw materials. However, there had been a restriction on doing the latter, due to new governmental regulations that were indroduced.

A new process concept was tested on a pilot scale. This was a cooperation effort among Andritz, Norske Skog and PFI.

The tensile strength target could be easily reached on a pilot scale, with a 10% to 30% reduction in energy consumption.

Other benefits included increased brightness, fewer shives and the removal of extractives. These pormising results were followed up by several pilot-scale trials and plans for full scale trials were made.

Although several challenges had to be solved prior to the scaling-up, the full scale results were positive. The process was included in the rebuilding of Norske Skog Pisa. Even though the full process could not be introduced, the new refining line has produced very good results.

Energy consumption has been lowered by 10% with a corresponding increase in production. Other benefits are fewer shives, higher brightness and less demand for reinforcement pulp. The mechanical pulp is now solely based on native grown Loblolly pine. The total savings amount to some USD 7 millions per year.

Process development and implementation on a full scale in other mills is continuing, with PFI as a research partner.

Contact: Lars Johansson