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

Abstract

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.

Description

technical field [0001] The invention belongs to the field of dye chemical raw material production, and is a technology for clean production and resource comprehensive utilization of vat dyes such as indigo. Background technique [0002] Indigo is an environmentally friendly primary color dye with a long history. It is widely used in the coloring of fabrics such as cotton, linen and viscose, especially in the warp dyeing of indigo denim. [0003] The current industrial production is to prepare indigo through the oxidation of 3-indoxyl salt, wherein the reaction process includes a certain amount of aniline acetate, sodium amide and a mixed alkali of sodium hydroxide and potassium hydroxide at 220 ~ 250 ° C Reaction to obtain 20-30% alkali melt of 3-indoxylate, which is dissolved in a large amount of water, oxidized by air, and then press-filtered, washed and granulated to obtain indigo. [0004] The molar ratio of KOH to NaOH in the oxidized dilute lye is about 0.6:1, which i...

AI Technical Summary

Problems solved by technology

[0008] In view of the serious imbalance of potassium-sodium ratio in the existing production, the potassium resources are not fully utilized, and the resources are seriously wasted. Therefore, the excess sodium hydroxide in the mixed alkali is separated and utilized through salt-forming and precipitation, and as much as possible Recovering the mixed alkali in washing water and alkali slag, so as to preserve and return the precious potassium hydroxide to the alkali system is our main direction