PURPOSE: To manufacture efficiently boric acid by treating sea water in a specified stage using an ion exchange resin.
CONSTITUTION: (1, 2) Sea water is treated to adjust the pH to 8W10, the CO2 content to ≤40ppm and the content of solid fine particles to ≤10ppm, and (3) the sea water is brought into contact with an ion exchange resin to allow contained boric acid to be adsorbed on the resin. (4) A mineral acid contg. boric acid is brought into contact with the resin to desorb the boric acid from the resin, (5) 1/5W3/5 of the boric acid contained in the mineral acid is recovered, and at the same time, the mineral acid contg. the remaining boric acid is recovered. (6, 7, 8) The recovered boric acid is dissolved in an aqueous soln. contg. boric acid, the soln. is brought into contact with an alkalifying agent, and the reaction product of the mineral acid with the agent is separated and removed. (9) Part of boric acid is separated and recovered from the aqueous soln. contg. boric acid, and at the same time, the aqueous soln. contg. the remaining boric acid is recovered. The mineral acid contg. boric acid recovered in the stage 5 is used in the stage 4, and the aqueous soln. contg. boric acid recovered in the stage 9 is used in the stage 6.
KANEYASU AKIRA
YAMAMOTO SHINICHI
