Semiboiled Saponification

The semiboiled soap production process with neutral fat is advantageous when simple processing is required and no glycerin recovery is provided. Production rates of 15 to 20 tons of fat per day and more are required for economic glycerin recovery. Compared to the fully boiled process, semiboiled processing has lower investment costs, can be operated easily and no waste water is produced.

Raw Materials

Fat and oil (beef tallow, palm oil, coconut oil and palm kernel oil, etc.) are commonly supplied in barrels. They are melted by steam, drained out into an oil collecting tank, fed with a pump into storage tanks, heated to about 70 to 75°C for intermediate storage.

Impurities of fats could affect the quality of soap in this process because crude soap production is already finished with saponification.

A solution of caustic soda (concentration about 32% NaOH) is one more component needed. Crystalline caustic soda (100% NaOH) is supplied in barrels. After removing the barrel bottoms caustic soda is dissolved in hot water produced by direct steam injection. From the dissolving tank the caustic soda solution is fed with a centrifugal pump into a storage tank and diluted by adding water until the concentration needed for saponification is reached.

Fat and caustic soda barrels have a weight of approx. 200 kg and are moved to the melting and dissolving tanks by a lifting monorail trolley.

Salt (NaCl) is needed in little amounts. It can be added to the batch type process either in solid or dilutated state by hand. The salt solution is prepared by dissolving crystalline salt (NaCl) in water as saturated solution. Depending on the batch composition a little amount of water is required, too.