Wspólnotowy Serwis Informacyjny Badan i Rozwoju - CORDIS

EuroFiber - Applications at Norske Skog ASA

Norske Skog ASA has mills producing wood-containing printing papers in six European countries. In all countries Norway spruce is the dominating species for virgin fibre production. In addition a substantial amount of recovered paper is used in the Norske Skog paper production. The majority of the mechanical pulp fibres contained in the recovered paper originate from Norway spruce. Thus in all respects our European operations are dominated by the fibre properties derived from Norway spruce.

Prior to the EuroFiber project there was only fragmented knowledge about the variability of Norway spruce grown at different European locations. The early conclusions of the project that spruce can be characterised reasonably well by two variables, basic wood density and fibre length, regardless of growth location and conditions is important as such. This result may seem somewhat remarkable as relates to basic density as e.g. thin walled small fibres may have the same basic density as thick walled large fibres. The combination of basic wood density and fibre length has, however, proven to be sufficient for characterisation of wood within the European region studied in the project.

Thus this conclusion provides:
- A proper basis for assessing the potential of wood collected from different sites;

- A clarity on which wood variables to trace whether physically measured or calculated based on models generated in this project or elsewhere.

- An opportunity to select suitable wood for different end product demands

In practise there are several other conditions and constraints to be considered in this selection of wood such as:
- Costs of wood in different areas;

- Costs of transportation;

- Time from felling to fibre processing;

- Natural availability of different combinations of wood properties e.g. high density and short fibre length.

If all conditions are known this project has provided a fair basis for assessing the economical value of a particular type of wood supplied to a selected mill.

The cost of wood is and will most likely continue to be the dominating cost of virgin fibre production in Europe. Thus this information will be used for wood raw material cost optimisation.

Different grades of printing paper have different demands on the fibre furnish used to produce the paper. As an example super calandered magazine paper (SC) put higher demands on surface properties and optical properties than newsprint. Wood with short fibre length is to be preferred for SC paper. While wood with long fibre lengths is to be preferred for sheets where strength properties are prioritised. Some of this knowledge was available earlier but rarely quantified to the point that it can be used for comparison between wood cost and fibre processing costs. In particular the pilot plant trial runs of the project have contributed and have shown:
- The possibility to select wood with targeted properties when harvesting in the forests;

- The ability to predict certain paper properties based on basic density, fibre length and degree of refining;

- The possibility to select refining intensity and yet reach equivalent paper properties for given wood properties but at different specific energy applications.

The major contribution of this work is to provide information for optimisation of the combination of wood properties and fibre processing. For a particular mill the selection of a particular type of wood can be compared to further fibre development. The former will have an impact on logistics & transportation costs and the latter on capital & energy costs – less suitable wood will demand more fibre treatment i.e. increased specific energy input to reach desirable paper quality targets.

The results derived from the pilot plant trials were tested in full-scale operation at the Norske Skog Follum mill in Norway. Two different wood assortments were selected and run on a high intensity refining line and applied to one paper machine. The results of the two wood assortments were compared both to each other and to the yearly averages of this production line. There are some interesting observations:
- The results achieved in the pilot plant trials were confirmed in full scale operation for the two selected wood assortments.

- The uniformity of the pulp produced with selected wood assortments was superior to that of the mix normally used.

- The specific energy demands compared at equal drainage (CSF) of the two assortments were less than that of the yearly average of the wood mix normally used.

- There are good possibilities for selecting certain more suitable wood assortments – within the currently available wood to the mill – for certain paper grades.

- The targeted wood selection will achieve a better cost benefit ratio of the paper production than is currently the case.

The implementation has started in the Follum mill. We have already seen some promising results. Hopefully the full potential will be reached within a year.

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Norske Skog
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