Mill demonstration of TMP production from forest thinnings: Pulp quality, refining energy, and handsheet properties

High-value, large-volume utilization of forest thinning materials from U.S. National Forests is a potentially important contributor to sustainable forest health. This study demonstrated the utilization of wood chips produced from thinnings for the production of thermomechanical pulp (TMP). Both whole-log chips (primarily from small-diameter logs, tops, and reject logs) and sawmill “residue” chips from a HewsawTM system (Mäntyharju, Finland) were evaluated. The residue chips produced in this study were substituted for a TMP mill’s standard residue chips up to about 50%. The whole-log chips were substituted for the mill’s whole-log chips up to about 30%. The results show that substitution of chips produced from forest thinnings reduced refining energy in all trials. Pulp quality was maintained throughout all trials.