Method for producing alumina from bauxite

A technology of bauxite and alumina, which is applied in the preparation of alkali metal aluminate/alumina/hydroxide, etc., can solve the problems of unindustrialized reports, low alumina concentration, and large water evaporation, and achieve Overcoming the harsh operating conditions, reducing the loss of lye, and the effect of easy operation

Inactive Publication Date: 2010-06-23
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

The improved Bayer process based on the treatment of medium and low-grade bauxite, such as the lime Bayer process, in addition to the requirements of high temperature and high pressure, also has the disadvantages of large red mud output and low resource utilization; High-pressure operating conditions, and due to the limitation of chemical reaction balance, the concentration of alumina in the stripping liquid phase is very low, resulting in large water evaporation and high cost. Although research has been started very early, it has not yet been industrialized. report

Method used

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  • Method for producing alumina from bauxite
  • Method for producing alumina from bauxite
  • Method for producing alumina from bauxite

Examples

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Embodiment 1

[0051] With the method for clean production of alumina by using low-grade diaspore bauxite of the present invention, a certain bauxite in Sanmenxia, ​​Henan is used as raw material to produce alumina, and the raw material composition of a certain bauxite in Sanmenxia, ​​Henan (mass percentage, wt%, the same below) as described in Table 1:

[0052] Table 1

[0053]

[0054] Its production process is as figure 1 The methods shown include:

[0055] 1. Mix a certain bauxite in Sanmenxia, ​​Henan Province, which is ground to 74-150 μm, with 40% by mass sodium hydroxide solution, and carry out dissolution reaction in a high-pressure reactor. The mass ratio of bauxite to sodium hydroxide solution is 1:3.5, the stripping reaction temperature is 200°C, the reaction pressure is 0.7MPa, and the stripping time is 1 hour to obtain a solid-liquid mixture of the stripping solution containing sodium aluminate and slag, and the relative stripping rate of alumina entering the solution is ...

Embodiment 2

[0062] With the method for the clean production of alumina by using low-grade diaspore bauxite of the present invention, a certain bauxite in Sanmenxia, ​​Henan Province as described in Table 1 is still used as a raw material for the production process of alumina. As described below:

[0063] 1. The dealumination circulating liquid of Example 1 is prepared with NaOH solution until the NaOH concentration is 50%, mixed with a certain bauxite in Sanmenxia, ​​Henan Province with a thickness of 74-150 μm, and stripping reaction is carried out in a high-pressure reactor, and the bauxite and hydrogen The mass ratio of the sodium oxide solution is 1:3, the stripping reaction temperature is 170°C, the reaction pressure is 0.45MPa, and the stripping time is 1 hour to obtain a solid-liquid mixture of the stripping solution containing sodium aluminate and slag, and the The relative dissolution rate of alumina is 99.4%;

[0064] 2. Cool the dissolved slag-containing suspension to 70°C for...

Embodiment 3

[0070] With the method for the clean production of alumina by using low-grade diaspore bauxite of the present invention, a certain bauxite in Sanmenxia, ​​Henan Province as described in Table 1 is still used as a raw material for the production process of alumina. As described below:

[0071] 1. The dealumination circulating liquid in Example 2 is prepared with NaOH solution until the NaOH concentration is 60%, mixed with a certain bauxite in Sanmenxia, ​​Henan Province of 74-150 μm, and stripping reaction is carried out in a high-pressure reactor, and the bauxite and hydrogen The mass ratio of the sodium oxide solution is 1:3, the stripping reaction temperature is 150°C, the reaction pressure is normal pressure, and the stripping time is 0.5 hours to obtain a solid-liquid mixture of the stripping solution containing sodium aluminate and slag, and the The relative dissolution rate of alumina is 93.2%;

[0072] 2. Cool the dissolved slag-containing suspension to 110°C for crys...

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Abstract

The invention relates to a method for producing alumina from bauxite. The method adopts sodium hydroxide solution in high molecular ratio, can efficiently extract alumina from indissolvable-diasporite type bauxite at low temperature under the normal/low pressure, is mild in operation conditions, and has actual dissolution rate up to over 90 percent. After stripped slag-containing suspension is subjected to flash evaporation cooling to crystallize and precipitate sodium aluminate hydrate crystals, the sodium aluminate hydrate crystals are dissolved in water or dilute alkali solution and then subjected to desilication, seed precipitation and calcination so as to obtain alumina meeting the requirements of metallurgical grade. Slag is dealuminized through sodium aluminate hydrate crystallization mother liquor and then is subjected to sodium removal so as to effectively reduce the content of sodium oxide and alumina in red mud, enable the composition, alkali content and other main indexes of obtained red mud physical phase to meet the requirements of raw materials for producing cement, reduce the loss amount of alkali solution and raise the resource utilization rate of bauxite. Dealuminized stripping solution can be recycled for stripping bauxite, so that industrial operability is greatly improved.

Description

technical field [0001] The invention relates to a method for producing alumina from bauxite, in particular to a method for cleanly producing alumina from middle and low grade diaspore type bauxite with an aluminum-silicon ratio of 3-7. Background technique [0002] With the continuous expansion of the production scale of the alumina industry, the consumption of bauxite mineral resources in my country is increasing day by day, and the situation of insufficient supply of high-grade bauxite has formed. Dissolved diaspore type bauxite (also known as medium and low grade bauxite). [0003] At present, the industrial production of alumina is basically produced by the alkaline method, including Bayer method, sintering method and Bayer-sintering combined method. The sintering method is mainly used to process bauxite with a low aluminum-silicon ratio. The process is complicated, the energy consumption is high, and the product quality is not as good as the Bayer method. More than 90%...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01F7/14
Inventor 张亦飞曹绍涛张懿郑诗礼钟莉孙旺
Owner INST OF PROCESS ENG CHINESE ACAD OF SCI
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