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Method for recycling mixed alkali liquor in indigo production

A technology of mixing alkali and indigo, which is applied in the direction of organic dyes and carbonate preparations, can solve the problems of high processing and production costs, difficult biochemical treatment of inorganic salts, waste of alkali resources, etc., to prevent waste of potassium resources and save recycling Process, water saving effect

Inactive Publication Date: 2014-02-05
JIANGSU TAIFENG CHEM
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

According to tracking statistics and analysis, during the post-treatment and washing process of indigo, the filter cake washing causes a large amount of alkali loss, and a large amount of tap water is required to dilute and wash the material. After the lost alkali enters the sewage treatment device, a large amount of acid is required. For neutralization, the treatment cost and production cost are high, and the formed inorganic salt is difficult to biochemically treat, which wastes alkali resources and causes large environmental pollution

Method used

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Embodiment Construction

[0014] The present invention will be further described below.

[0015] A method for producing and recovering mixed lye from indigo includes the following steps:

[0016] (1) After the indigo oxidation process, it is sent to the filter press for pressure filtration, the press filter filtrate is concentrated and filtered to obtain the alkali residue, and the press filter concentrate is sent to the reactor;

[0017] (2) Washing step (1) After pressing and filtering the indigo, add the alkali residue in step (1) to the washing water, increase the temperature and stir until the alkali residue is completely dissolved, and then naturally cool to room temperature for filtration. The filtrate is concentrated into a concentrated alkali solution and sent to the reaction Kettle; filter residue adopts saturated Na 2 CO 3 Na is filtered after washing 2 CO 3 Solid, the filtrate is concentrated into concentrated lye and sent to the reactor;

[0018] (3) Pass CO into the reactor 2 When the reaction te...

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Abstract

The invention relates to a method for recycling mixed alkali liquor in indigo production, and the method comprises the following steps: feeding indigo into a filter press so as to be filter-pressed after an oxidation process, concentrating a filter-pressing filtrate to obtain caustic sludge, and feeding a filter-pressing concentrated liquor into a reaction still; washing the indigo filter-pressed in the step (1), adding the caustic sludge of the step (1) into washing water, warming and stirring until the caustic sludge is completely dissolved, naturally cooling to room temperature, filtering, concentrating the filtrate as a concentrated alkali liquor, and then feeding the concentrated alkali liquor into the reaction still; washing filter residue by using saturated Na2CO3, filtering to obtain a Na2CO3 solid, concentrating the filtrate as the concentrated alkali liquor, and then feeding the concentrated alkali liquor into the reaction still, introducing CO2 into the reaction still, stopping introducing CO2 when the reaction temperature is at 60-70 DEG C, cooling to room temperature, stirring for 1-2 hours, crystallizing, filtering to obtain mother liquor and crude product Na2CO3, concentrating the filtrate as the concentrated alkali liquor, and then feeding the concentrated alkali liquor into the reaction still in the step (3). By adopting the method of circularly recycling, the filter-pressed filtrate, the washing water and the KOH in the caustic sludge are effectively recycled.

Description

Technical field [0001] The invention belongs to the technology for the recovery of dye chemical raw materials, in particular to a method for producing and recovering mixed lye from indigo. Background technique [0002] Indigo is a green and environmentally friendly vat dye with a long history. It is widely used in the dyeing of cotton fabrics, especially the warp yarn of indigo denim products. [0003] The current industrial production is to prepare indigo through the oxidation of 3-indoxylate. The reaction process includes a certain amount of anilinoacetate, sodium amide, and a mixed alkali of sodium hydroxide and potassium hydroxide at 220~250℃. After the reaction, 20-30% of the alkali melt of 3-indoxylate is obtained. The alkali melt is dissolved in a large amount of water, oxidized by air, and then filtered, washed and dried to obtain indigo. [0004] In the alkali fusion, oxidation and post-treatment processes of indigo synthesis, the alkali is mainly used in the alkali fusion ...

Claims

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Application Information

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IPC IPC(8): C09B67/28C01D7/07
Inventor 吴德生李留德毛永生常青
Owner JIANGSU TAIFENG CHEM
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