Effects of Mountain Pine Beetle Grey-stage Infestation and Chip Moisture Content on TMP Pulping of Lodgepole Pine, and Water Uptake Studies, 2008 Engineering, Pulping and Environmental Conference

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We performed pilot-plant thermomechanical pulping on green and dry, mountain pine beetle-infested, grey-stage lodgepole pine (LPP) sapwood chips with different moisture contents. The energy requirements and the tensile strength of the thermomechanical pulps (TMPs) from the dry, early-grey chips were similar to those from the green chips, while there was an indication of slightly higher energy requirements and lower tensile strength of the pulps from the late-grey chips. The late- or early-grey TMP had lower sheet density due to the lower moisture content of the chips, and lower ISO brightness and higher handsheet surface roughness than the green TMP.

Water-uptake studies indicated that it was possible to significantly increase the moisture content of the dry, early-grey LPP chips by soaking the chips for 8-10 min at optimal conductivity (~200 µS/cm) and pH (~6.0). The Environmental Scanning Electron Microscopy (ESEM)-Energy Dispersive Spectroscopy chemical tracer technique provided qualitative information on water movement within 10 min of water soaking of the green and late-grey LPP blocks. ESEM studies also showed the presence of fissures, fungal hyphae and incipient decay in the late-grey blocks.