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Method for dissolving out alumina in bauxite by using sodium hydroxide

A sodium hydroxide and bauxite technology, applied in the direction of alumina/aluminum hydroxide, can solve the problem of high energy consumption and achieve the effect of improving the dissolution efficiency

Inactive Publication Date: 2010-12-15
BEIJING UNIV OF CHEM TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Since the decomposition rate of the seed fraction is only ~50%, the mass ratio of aluminum to sodium in the circulating mother liquor is about 0.5, and the circulating mother liquor contains a large amount of aluminum hydroxide, thus making it effective for the dissolution of alumina in bauxite and material circulation. Efficiency can only be exerted at about 50%, and energy consumption is relatively high

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0016] Example 1 Sodium hydroxide solution and Bayer method seed separation mother liquor are compared to the stripping performance of alumina in bauxite

[0017] Get the caustic alkali concentration as 194g / L (according to Na 2 O), the total alkalinity is 215g / L (according to Na 2 O meter), Al 2 o 3 The mother liquor of the Bayer method with a content of 96g / L is the dissolution agent, according to the Na content of the dissolution agent 2 O and Al of bauxite 2 o 3 The molar ratio is 1.29, and the bauxite with aluminum-silicon ratio A / S=5.07 is subjected to high-pressure stripping in a high-pressure vessel, and the stripping temperature is controlled at 240-280°C, and the stripping time is 40 minutes. The dissolution results show that the aluminum-silicon ratio of red mud is A' / S'=1.28, and the effect of circulating mother liquor on Al in bauxite 2 o 3 The dissolution rate η=[1-(A' / S') / (A / S)]×100%=74.8%, Al in the dissolution solution 2 o 3 The content rose to 190g / L...

Embodiment 2

[0019] Embodiment 2 The relationship between the concentration of sodium hydroxide solution and the aluminum-silicon ratio of bauxite and the dissolution rate of alumina

[0020] Respectively at a concentration of 100, 200 or 300g / L (as Na 2 The sodium hydroxide solution of O meter) is stripping agent, investigates its to aluminum-silicon ratio A / S and is respectively the stripping efficiency of aluminum oxide in the bauxite of 4.02,5.07 or 7.15, selects stripping agent and the sodium aluminum mole of bauxite The ratios are 1.0, 1.3 or 1.6, respectively. After pre-desilication treatment at low temperature, high-pressure dissolution was carried out in a high-pressure vessel at a temperature of 240-280°C for 60 minutes, and the alumina dissolution rate of bauxite was analyzed and calculated. The results are shown in the table below.

[0021] serial number

[0022] 1

[0023] From the data in the table above, it can be seen that with Na 2 Sodium hydroxide s...

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Abstract

The invention discloses a method for dissolving out bauxite to produce alumina by using sodium hydroxide solution as dissolving agent. Compared with a Bayer's method using seed separation mother liquor as dissolving agent, the method of the invention can greatly improve the dissolving capacity of unit alkali liquor, and can be used for the dissolution of the alumina in the low-grade bauxite afterpre-desilication treatment. The method reduces futile cycle of materials, and remarkably improves the production efficiency of equipment. The sodium hydroxide solution used by the method can be recycled by using film electrolytic sodium aluminate to decompose mother liquor, namely sodium carbonate solution.

Description

technical field [0001] The invention relates to the field of alumina production, in particular to a method for dissolving alumina in bauxite by using high-purity and high-concentration sodium hydroxide solution. technical background [0002] At present, the methods of alumina production at home and abroad mainly include Bayer method, sintering method and combined method. The combined process is simply a combination of the Bayer process and the sinter process. The Bayer process has low energy consumption and is currently a process method commonly used in countries all over the world to produce alumina. The sintering method has high energy consumption and is only used for alumina production of low-quality ores with high silicon content. The Bayer method process is: dissolve the alumina in the bauxite with the sodium hydroxide solution containing sodium aluminate, and then use the method of adding aluminum hydroxide seed crystals (seeds) to decompose and separate the dissolve...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C01F7/02
Inventor 钮因健吕子剑万平玉张吉龙吴钢张学英陈咏梅潘军青孟杰邓洁
Owner BEIJING UNIV OF CHEM TECH