Sulphate Soap Separation from Wood Mixture Cooking Black Liquor

The sulphate soap separation from black liquor is influenced by a large number of factors: wood species composition, physical properties and composition of liquor components. The bases of the process are widely researched, but the influence of some factors requires additional research. Meanwhile, due to the diversity of the processed wood species composition and different cooking conditions, the composition and properties of the liquor may differ significantly, and the soap separation at different mills does not always follow the patterns established in previous studies. The purpose of this research is to determine the optimal parameters for the sulphate soap separation from semi-steamed black liquor from the mixed wood cooking, as well as the consumption of additives to increase the sulphate soap yield. The research is based on the principles of mathematical modeling of processes and was carried out in laboratory conditions. We used the method of a planned experiment in the form of a second-order rotatable compositional uniform plan in order to obtain a mathematical model of the soap skimming process, depending on the chosen variables and to determine the optimal values of the process parameters. In the experiment, the following factors were varied: temperature, soap settling time and liquor density. The optimal values of these factors for sulphate soap separation from black liquor were determined, a mathematical model of the process was developed, and the optimal parameters for the effective sulphate soap settling were determined as results of the experiment. Adjusting the soap skimming production conditions to the optimal can increase soap skimming from semi-steamed liquors by 20 %. As a result of evaluating the effect of adding surfactants of different nature to black liquor of different density on the completeness of sulphate soap separation, we have found their optimal dosages, which give the maximum positive effect – an increase in soap yield by 15 %. For citation: Starzhinskaya E.V., Kryazhev A.M., Tret’yakov S.I., Gluhanov A.A. Sulphate Soap Separation from Wood Mixture Cooking Black Liquor. Lesnoy Zhurnal = Russian Forestry Journal, 2022, no. 6, pp. 178–192. (In Russ.). https://doi.org/10.37482/0536-1036-2022-6-178-192