Process for the production of dithionites

摘要

An improvement in the process for producing anhydrous dithionites by reacting formic acid or a formate with an alkali compound and sulfurous acid anhydride in a mixture of water and organic solvent; filtering dithionite crystals from the mother liquor; and washing the dithionite crystals with an organic solvent as a washing liquid and then drying the dithionite crystals. The improvement comprises dividing the washing liquid into two portions which are discharged as the washing liquid first discharged and the washing liquid discharged subsequently from the washing operation and treating the washing liquid first discharged to convert substances contained therein which inhibit the production of dithionite into harmless substances and recycling both the treated washing liquid first discharged and the washing liquid discharged subsequently which does not require treatment as a reaction solvent.