Recovery, balance adjustment and comprehensive utilization technology for mixing alkali in indigo blue production

A purpose of the invention is to achieve sodium reduction, potassium retention, and no use or less use of potassium hydroxide based on recovery utilization of mixing alkali and potassium-sodium balance adjustment in an indigo blue production process. According to the present invention, waste alkali residue, washing alkali water and surplus sodium hydroxide in oxidation alkali in the existing production are utilized, bicarbonate or carbon dioxide, and a plurality of ways are applied and introduced to the concentrate, and difference between dissolubility of sodium carbonate and potassium carbonate and a common ion effect are delicately utilized to generate sodium carbonate precipitate and separate, such that removal of surplus sodium hydroxide in the liquid alkali is achieved without introduction of new impurities, the sodium carbonate product is co-produced, about 0.5 ton of the potassium hydroxide is saved and about 1 ton of the sodium carbonate is by-produced when per ton of the indigo blue product is produc