| 摘要 |
PURPOSE:To produce boric acid and sodium sulfate with small consumption of energy by dissolving borax in sulfuric acid, depositing boric acid from the resulting soln. by cooling and bringing the remaining soln. into liq.-liq. contact with an extracting reagent for boric acid. CONSTITUTION:Borax, sulfuric acid and water are fed to a stage for dissolving and stirring starting material and the borax is dissolved by heating to prepare a mixed soln. contg. boric acid and sodium sulfate. This soln. is cooled (a) to deposit boric acid, which is separated and purified. The remaining mixed soln. is successively passed through a first extracting stage consisting of a stirring stage bI and a separating stage dI, a second extracting stage consisting of a stirring stage bII and a separating stage dII, and a third extracting stage consisting of a stirring stage bIII and a separating stage dIII. In the extracting stages, the soln. is brought into liq.-liq. contact with an org. extracting reagent for boric acid such as 2-ethyl-1,3-hexanediol to extract and separate boric acid from sodium sulfate. The extracting reagent contg. the boric acid is introduced into a back extracting stage consisting of stirring stages cI, cII and separating stages eI, eII. In the back extracting stage, the reagent is mixed with dil. sulfuric acid to back-extract the boric acid and this boric acid is returned to the dissolving and stirring stage. The resulting sodium sulfate soln. is sent to a stage for producing sodium sulfate.
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