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Method for alumina separation in chromium salt clean production

A technology of clean production and separation method, applied in the directions of alumina/aluminum hydroxide, liquid solution solvent extraction, etc., can solve the problems of unsuitable economical application in the extraction industry, unsuitable high-potassium alkali system, difficult stripping, etc.

Inactive Publication Date: 2013-07-10
INST OF PROCESS ENG CHINESE ACAD OF SCI
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

But its technical scheme is not very applicable to the high potassium alkali system of the present invention, and specific reason is: (1) fluoroalcohol and macrocyclic crown ether cost are high, are not suitable for economical application in extraction industry; (2) selected alkylphenol extracts The agent is suitable for treating low-concentration potassium hydroxide solution. Since extraction and back-extraction are reverse processes, extraction is easy but back-extraction is difficult, and vice versa. If the extraction agent is highly acidic, it can extract potassium hydroxide in a system with a lower alkali concentration. , but stripping can only obtain low-concentration lye; therefore, the potassium hydroxide solution obtained after the selected alkylphenol extractant extraction / stripping treatment will bring additional evaporation when it is connected with the sub-molten salt chromium salt cleaning process energy consumption

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0023] 2.5mol / L 2-tert-butyl-4-ethoxyphenol (CAS: 25762-84-9) diluted with C10-C11 aliphatic alcohol and C7-C8 alkane is used as extractant, and recycled lye (hydrogen Potassium oxide concentration is 500g / L, caustic ratio is 2.5) According to the oil-water ratio of 10:1, it is subjected to single-stage extraction at 40°C, the extraction time is 10 minutes, the concentration of potassium hydroxide in the extracted water phase is 343g / L, and the caustic ratio is 1.37 , to meet the requirements of species classification; the dilute lye with potassium hydroxide concentration of 170g / L for organic loading is subjected to single-stage back extraction at 60°C according to the oil-water ratio of 10:1, and the back extraction time is 10 minutes. Potassium concentration is 327g / L, return to sub-molten salt chromium salt cleaning process system.

Embodiment 2

[0025] 0.5mol / L of 2-tert-butyl-5-pentadecylphenol (CAS: 32360-03-5) diluted with n-octanol is used as the extractant, and the circulating lye (potassium hydroxide concentration is 600g / L) , the caustic ratio is 3.0) according to the oil-water ratio of 5:1 at 20 ℃ through three-stage countercurrent extraction, the extraction time is 20 minutes, the concentration of potassium hydroxide in the extracted flowing water phase is 310g / L, and the caustic ratio is 1.55, which meets the requirements of species classification; The dilute lye with a potassium hydroxide concentration of 50g / L for organic loading is subjected to three-stage countercurrent stripping at 50°C according to the oil-to-water ratio of 4:1, and the stripping time is 20 minutes. L, return to sub-molten salt chromium salt cleaning process system.

Embodiment 3

[0027] 1.5mol / L 2-tert-butyl-4-(3-hydroxypropyl)phenol (CAS: 95970-34-6) diluted with C6-C8 fatty alcohol and C12-C14 alkane is used as extractant, and the The lye (potassium hydroxide concentration is 450g / L, caustic ratio is 2.5) is subjected to 5-stage countercurrent extraction at 30°C according to the oil-water ratio of 7:1, the extraction time is 15 minutes, and the concentration of potassium hydroxide in the extracted water phase is 321g / L , the caustic ratio is 1.78, which meets the requirements of species classification; the dilute lye with a potassium hydroxide concentration of 160g / L for organic loading is subjected to 5-stage countercurrent stripping at 60°C at an oil-to-water ratio of 7:1, and the stripping time is 15 minutes. The concentration of potassium hydroxide in the aqueous phase of the extraction flow is 287g / L, which is returned to the sub-molten salt chromium salt cleaning process system.

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Abstract

The invention relates to a method for separating potassium hydroxide from a circulating potash solution with a high caustic ratio and high caustic potash concentration by a liquid-liquid extraction technology to adjust the caustic ratio of the circulating potash solution to a caustic ratio meeting aluminum hydroxide seed precipitation requirements (below 1.8) and to obtain a high-concentration potassium hydroxide alkali solution simultaneously. The method adopts an alkylphenol as an extractant, transfers a part of potassium in a circulating potash system to an oil phase through a liquid-liquid extraction technology, and then transfers potassium loaded by the oil phase to a water phase by dilute potassium hydroxide alkali solution, wherein the adopted alkylphenol is dissolved in a fatty alcohol, an alkane or a mixture of the fatty alcohol and the alkane; ortho-positions of a phenolic hydroxyl group of the alkylphenol are displaced by tert-butyl groups; and other meta-positions and para-positions are displaced by alkoxy groups, hydroxyalkyl groups or alkyl groups. After back extraction, the extractant can be recycled. The circulating potash solution adjusted on a caustic ratio can be subjected to further seed precipitation to obtain aluminum hydroxide. The back extraction can be carried out in an alkali concentration range of a circulating alkali solution adopted by a chromium salt cleaning process. A use of the method provides an effective approach for aluminum impurity recovery in chromium salt clean production adopting a sub-molten salt.

Description

technical field [0001] A method for separating alumina in a chromium salt clean production process, involving a liquid-liquid extraction technology to separate potassium hydroxide from circulating potassium lye with high caustic ratio and high caustic potassium concentration, thereby adjusting the caustic ratio of lye to hydrogen Alumina can be planted according to requirements, and at the same time obtain high-concentration potassium hydroxide lye. technical background [0002] Chromium is an important strategic metal resource in my country, and the chromium salt industry is a key industry intersecting inorganic chemicals and metallurgical materials. Due to the backwardness of traditional technology, the recovery rate of chromium is only 75%, and 2.0-2.5 tons of highly toxic chromium slag is produced per ton of product. In order to reduce the emission of highly toxic chromium slag from the source, the Institute of Process Engineering, Chinese Academy of Sciences has indepe...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C01F7/02B01D11/04
Inventor 郑诗礼张盈王晓辉马淑花王少娜杜浩张懿
Owner INST OF PROCESS ENG CHINESE ACAD OF SCI