Canadian Forest Service Publications
Waste fatty acid addition to black liquor to decrease tall oil soap solubility and increase skimming efficiency in kraft mills pulping mountain pine beetle-infested wood. 2009. Uloth, V.; Shewchuk, D.; Guy, E.; van Heek, R. Natural Resources Canada, Canadian Forest Service, Pacific Forestry Centre, Victoria, BC. Mountain Pine Beetle Working Paper 2009-26. 24 p.
Issued by: Pacific Forestry Centre
Catalog ID: 31184
Means to economically increase soap recovery by increasing the fatty acid/resin acid ratio of the product tall oil were investigated. Lab tests showed that the addition of tall oil fatty acids, or waste fatty acids from canola processing, could decrease tall oil soap solubility and potentially increase soap skimming efficiency in the affected mills. Analyses indicated that adding waste fatty acids could be economical at fatty acid/resin acid ratios of up to 2.5, even when the recovered tall oil is simply burned in the mill's lime kiln, if natural gas and oil prices were high. Full-scale mill trials subsequently run over a 4-day period confirmed that waste fatty acid addition decreased tall oil soap solubility, increased tall oil soap skimming efficiency, and produced a higher-quality soap that was readily processed in the mill's tall oil plant.