Abstract: A semi-continuous acidulation process for converting tall oil soap to crude tall oil is disclosed. Reactants are continuously mixed, and the product mixture is continuously transferred to a settling tank having a conical lower section and a capacity at least 25 times that of the mixer. Batches settle to give a solid phase comprising calcium sulfate, a clean spent acid phase, a dirty spent acid phase, and a crude tall oil phase. Each phase is removed sequentially through a port at or near the bottom of the settling tank. Compared with traditional batch acidulation, continuous mixing minimizes the corrosive environment and enables the use of less expensive materials for the settling tank. Sequential removal of four phases from one port allows calcium sulfate to be purged from every batch, permits clean separation of clean spent acid from dirty spent acid, and enables clean recovery of tall oil.

Abstract: A method for producing crude tall oil from black liquor soap while removing calcium carbonate and lignates is disclosed. Black liquor soap is first combined with an alkaline ash medium having a lower concentration of lignates and inorganic solids than the black liquor soap, to form washed tall oil soap, fortified brine, lignates, and calcium carbonate. The washed tall oil soap is then separated from the fortified brine, lignates, and calcium carbonate, by centrifugation, decantation, filtration, settling, or a combination of these techniques. Acidification of the washed tall oil soap gives crude tall oil and a spent acid mixture. The crude tall oil is separated from the spent acid. The spent acid is made alkaline, and at least a portion of it is returned for use as alkaline wash medium. The method avoids accumulation of calcium sulfate in acidulation units.

Abstract: A method for producing crude tall oil from black liquor soap while removing calcium carbonate and lignates is disclosed. Black liquor soap is first combined with an alkaline ash medium having a lower concentration of lignates and inorganic solids than the black liquor soap, to form washed tall oil soap, fortified brine, lignates, and calcium carbonate. The washed tall oil soap is then separated from the fortified brine, lignates, and calcium carbonate, by centrifugation, decantation, filtration, settling, or a combination of these techniques. Acidification of the washed tall oil soap gives crude tall oil and a spent acid mixture. The crude tall oil is separated from the spent acid. The spent acid is made alkaline, and at least a portion of it is returned for use as alkaline wash medium. The method avoids accumulation of calcium sulfate in acidulation units.