Influence of Refining Temperature and Intensity (Disc Rotating Speed) on TMP Energy Consumption and Pulp and Fibre Fraction Properties, 1999 International Mechanical Pulping Conference Proceedings

Ilkka.Nurminen@kcl.fi

KCL (The Finnish Pulp and Paper Research Institute)

Pilot trials at KCL showed that in first-stage refining the bonding ability of long fibres increased with increasing refining intensity (increased disc speed) and at the same time the refining energy decreased. Too high a refining intensity, however, caused increased fibre cutting and the fibre bonding ability started to decrease. Raising the temperature in the first stage improved long fibre bonding ability. This was reflected as a dramatic decrease in shive content. The higher the temperature, the lower the brightness. The middle fraction fibres and fines had the best bonding ability at a certain freeness when refined at low intensity (low disc speed) Refining at high intensity led to extensive fibre cutting, which had a disastrous effect on the bonding and scattering abilities of the different

fibre fractions.

In second-stage refining the long fibres developed differently, as low refining intensity and high energy consumption seemed to result in high bonding ability. The poorly bonding but probably largely unbroken long fibres after the first stage seemed to have even higher potential to develop into strongly bonding long fibres than those refined at high intensity in the first stage. Higher refining intensity (higher disc speed) had a greater tendency to cut fibres without any major decrease in energy consumption when a dense plate pattern was used.