Low Consistency Refining of Oxalic Acid Pretreated Wood Shavings

The objective of this study was to evaluate the potential use of wood shavings as a raw material for the low consistency (LC) refining at the primary refining state to significantly reduce electrical energy consumption. It was possible to produce wood shavings with longer fibre length than wood chips. Oxalic acid, followed by alkaline peroxide, was applied to both wood shavings and wood chips before LC refining. LC refined wood shavings were found to be a low energy raw material. The refining energy was reduced by about 33% using wood shavings compared to wood chips at a given freeness, and oxalic acid pretreatment of wood shavings further reduced the refining energy by approximately 57%. Tensile strength and brightness of LC refined wood shavings was found to be higher than high consistency refined wood chips. Oxalic acid pretreatment further improved the tensile strength of LC refined wood shavings, but not the brightness. This study demonstrates the potential to develop a novel mechanical pulping process that products high tensile, high brightness pulp with half the electrical energy consumption.