Method for re-use of aqueous co-product from manufacture of sodium dithionite

摘要

Aqueous co-product, produced by distillation of reaction filtrate from a batch reaction for manufacturing sodium dithionite by reacting sodium formate, sodium hydroxide, and sulfur dioxide in aqueous methanol solution, is rapidly evaporated to remove about 80% of its water content, so that only the determined quantity of water remains with its determined contents of alkali metal compounds, and is utilized as an admixed component of a succeeding batch.