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 produced, and a new process
route with characteristics of alkali resource comprehensive utilization and delicate potassium and sodium balance is developed. With the present invention, characteristics of low investment,
resource saving, cleaning,
environmental protection, economy, novelty, strong practicality and wide generalization application value are provided, significant theory and application values are provided for the
circular economy and
sustainable development strategy, ??and wide
social benefits,
economic benefits and ecological benefits are provided.