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Method for producing aluminum hydroxide from sodium aluminate solution

A technology of aluminum hydroxide and sodium aluminate, which is applied in the field of production of aluminum hydroxide, can solve the problems of long crystallization decomposition time, low material circulation efficiency, low decomposition rate, etc., achieve shortened reaction time, increase unit production capacity, and decomposition rate Improved effect

Inactive Publication Date: 2008-08-06
INST OF PROCESS ENG CHINESE ACAD OF SCI
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  • Summary
  • Abstract
  • Description
  • Claims
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Problems solved by technology

[0005] The purpose of the present invention is to overcome a series of problems such as long decomposition time of traditional seed fraction crystallization, large seed ratio, low decomposition rate and low material circulation efficiency, so as to provide an aluminum Method for producing aluminum hydroxide from sodium acid solution

Method used

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  • Method for producing aluminum hydroxide from sodium aluminate solution
  • Method for producing aluminum hydroxide from sodium aluminate solution
  • Method for producing aluminum hydroxide from sodium aluminate solution

Examples

Experimental program
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Embodiment 1

[0028] This embodiment includes the following steps:

[0029] 1) to Al 2 o 3 Concentration is 50g / L, in the sodium aluminate solution that caustic ratio is 1.4, add methanol, wherein, the volume ratio of two kinds of solutions is sodium aluminate solution: methanol=1: 0.6;

[0030] 2) Put the above-mentioned mixed solution in a reaction vessel kept at 30° C. for airtight stirring, and stop the reaction after half an hour;

[0031] 3) Liquid-solid separation of the reaction product in step 2) to obtain aluminum hydroxide solid phase and mother liquor; the content of sodium oxide in the mother liquor is 35g / L, and the caustic ratio is 13; the solid phase is washed in 50°C washing water for 3-5 times Dry at 60°C after slurry washing to obtain aluminum hydroxide product, and the decomposition rate of sodium aluminate in this example is 89%.

[0032] The scanning electron microscope of example 1 gained aluminum hydroxide is as figure 1 As shown, the particle size of the product...

Embodiment 2

[0034] In this example, Al in the sodium aluminate solution 2 o 3 The concentration is 100g / L, the caustic ratio is 1.4, the volume ratio of each solution in the initial mixed liquid sodium aluminate solution:methanol=1:1.5, the reaction temperature is 60°C, the reaction time is 8 hours, the washing water temperature is 90°C, and the drying temperature It is 110 DEG C, and all the other conditions and steps are the same as in Example 1. After the reaction, the concentration of sodium hydroxide in the mother liquor was 45g / L, the caustic ratio was 50, and the decomposition rate of alumina was 94%.

[0035] The mother liquor obtained above is subjected to vacuum fractionation at 65° C., and the obtained low boiling point component is methanol, which can be returned to step 1) and reused for preparing sodium aluminate solution.

Embodiment 3

[0037] Al in the sodium aluminate solution in the present embodiment 2 o 3 The concentration is 150g / L, the caustic ratio is 2.6, the mixed liquid is configured according to the volume ratio of sodium aluminate solution:methanol=1:3, the reaction time is 12 hours, the washing water temperature is 70°C, and the drying temperature is 80°C. The rest of the conditions and steps are the same Example 1. After the reaction, the concentration of sodium hydroxide in the mother liquor was 50 g / L, the caustic ratio was 13, and the decomposition rate of alumina was 80%.

[0038] The mother liquor obtained above is subjected to vacuum fractionation at 80° C., and the obtained low boiling point component is methanol, which can be returned to step 1) and reused for preparing sodium aluminate solution.

[0039] The scanning electron microscope of example 3 gained aluminum hydroxide is as figure 2 As shown, the particle size of the product is around 500nm.

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Abstract

The invention provides a method for producing aluminum hydroxide by using sodium aluminate solution, which inculdes the following steps: 1) the sodium aluminate solution with alumina concentration of 50-250g / L and caustic ratio of 1.4-2.6 is evenly mixed with methanol; 2) mixed liquid of the step 1) is closed under 30-80 DEG C and stirred for 0.5-24 hours to precipitate crystal of the aluminum hydroxide; 3) the reacted liquid is carried out solid-liquid separation to obtain solid phase and mother liquor; the solid phase is washed in 3-5 level slurry countercurrent; temperature of washing water is 50-90 DEG C; then the solid phase is dried under 60-110 DEG C to obtain product of the aluminum hydroxide. The method for producing the aluminum hydroxide of the invention has rapid reaction speed and can greatly shorten the reaction time and do not need to add crystal seed of the aluminum hydroxide, thus solving the problem of low productivity of the device caused by that a great deal of the crystal seed occupies the decomposer, the method greatly improves the total efficiency of the preparation method; as the method has a decomposition rate of sodium aluminate solution largely more than that of Bayer process; the method can improve the decomposition rate of the prior rate to more than 90 percent from 50 percent and greatly increase cycle efficiency of the mother liquor.

Description

Technical field: [0001] The invention relates to a method for producing aluminum hydroxide, in particular to a method for producing aluminum hydroxide using sodium aluminate solution. Background technique: [0002] Aluminum hydroxide is an important chemical metallurgical raw material, 90% of which is used for roasting alumina as a raw material for electrolytic aluminum, and it is also widely used in medicine, catalyst, plastic, papermaking, refractory material, abrasive and electronic products. [0003] The Bayer process is the main method for the industrial production of alumina. The essence of the Bayer process is to make the alumina in the bauxite react under high temperature and high pressure through the Bayer cycle to dissolve it in the form of sodium aluminate solution. The sodium aluminate solution is cooled and diluted, separated from the red mud, and the solution is decomposed by adding seeds Aluminum hydroxide can be obtained by calcining to obtain alumina. Wher...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01F7/14
Inventor 郑诗礼王雪张亦飞张懿
Owner INST OF PROCESS ENG CHINESE ACAD OF SCI
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