Wood resin is released from chips during mechanical pulping and distributed throughout the mill process waters. For mills with relatively closed white-water loops, resins can build up in the process to a level where deposits form in pipes and paper machine components causing product quality issues and increased maintenance. Current resin removal technologies effectively reduce extractive levels in mill waters, however they do not enable easy recovery of the resin products. Recovery of this resin could have multiple benefits for mechanical pulp mills, such as improved product quality, reduced effluent treatment requirements and new biochemical product (revenue) opportunities. De-oiling hydrocyclones are commonly used in the oil and gas industry to remove low levels of oil contaminants from process waters. Similarly, this technology could be adapted to pulp mills for the removal and recovery of colloidal resin. The potential for using a de-oiling hydrocyclone to recover wood resin was investigated using model systems and pulp mill pressates with a range of processing conditions. Up to 97% separation efficiency was achieved using model systems, however negligible separation was achieved using pulp mill pressates.
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