METHOD FOR SEPARATING AND PURIFYING AN AQUEOUS MIXTURE, WHOSE MAIN COMPONENTS ARE ACETIC ACID AND FORMIC ACID

摘要

The invention relates to a method for separating and purifying an aqueous mixture, whose main components are acetic acid, formic acid and high-boiling components, by extraction using a solvent in a cyclic process. According to said method, the raffinate stream is fed with a large portion of the water to a solvent stripping column (11) in order to remove the water and the extract stream is supplied to a solvent distillation column (8). From said column, in a first step, a mixture (A) consisting of water and solvent is separated at the head and a mixture (B) consisting of acetic acid, formic acid and high-boiling components is separated at the bottom. After separation of the formic acid in a column (29) using an auxiliary agent in a type of azeotropic distillation, mixture (B) is subsequently separated in an acetic acid distillation column into pure acetic acid and high-boiling components and mixture (A) is fed to a phase separator (25), the aqueous phase with residual solvent thus obtained being re-supplied to the solvent stripping column (11) and the organic phase being re-supplied to the extractor (7).