Method for reclaiming alumina and sodium oxide in red mud of Bayer process

A Bayer process red mud and alumina technology, which is applied in the direction of alumina/aluminum hydroxide, alkali metal oxides, etc., can solve the problems of high energy consumption, restrictions on the recovery and comprehensive utilization of valuable metals in red mud, and low recovery rates. Achieve the effects of reducing production energy consumption, improving industrial operability, and simplifying the production process

Inactive Publication Date: 2009-12-23
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 above methods have problems such as high energy consumption or low recovery rate, which seriously restricts the recovery and comprehensive utilization of valuable metals from red mud.

Method used

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  • Method for reclaiming alumina and sodium oxide in red mud of Bayer process

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0018] Use the method of the present invention to reclaim the alumina of Bayer process red mud, take the Bayer process red mud of a factory in Henan as an example, the composition (wt%) of this Bayer process red mud is as follows:

[0019]

[0020] Its recycling steps are:

[0021] Mix the Bayer process red mud with 30% NaOH solution by weight and put it in the reaction kettle. After 1 hour, the mixed reaction product containing lye, sodium aluminate and dealuminated red mud was obtained. After the mixed reaction product was cooled to 100°C, the reaction kettle was taken out and kept in an oven at 100°C for heat preservation and suction filtration, and the alkali containing sodium aluminate was separated. solution and dealuminated red mud, A / S=0.49 (A is the weight percent of alumina and S is the weight percent of silicon oxide) in the dealuminated red mud components at this time, and the recovery rate of alumina from Bayer process red mud is 70.06%;

[0022] The alkali so...

Embodiment 2

[0025] Mix the Bayer process red mud with 45% NaOH solution by weight and place it in the reaction kettle. After 2 hours, the mixed reaction product containing lye, sodium aluminate and dealuminated red mud was obtained. After the mixed reaction product was cooled to 100°C, the reaction kettle was taken out and kept in an oven at 100°C for heat preservation and suction filtration, and the alkali containing sodium aluminate was separated. solution and dealuminated red mud, A / S=0.11 (A is the weight percent of alumina and S is the weight percent of silicon oxide) in the dealuminated red mud components at this time, and the recovery rate of alumina from Bayer process red mud is 93%;

[0026] The alkali solution (filter mother liquor) containing sodium aluminate obtained is put into the crystallization reactor, the caustic ratio of the crystallization mother liquor obtained by filtering after crystallization for 8 hours is raised to 32, and the caustic ratio of the hydrated sodium ...

Embodiment 3

[0029] Mix the Bayer process red mud with a NaOH solution with a concentration of 50% by weight, and add a certain amount of aluminum hydroxide, so that the caustic ratio in the resulting solution is 40, and the proportion by weight is Bayer process red mud: NaOH = 1:8, put it into the reaction kettle and heat up to 230°C, and react at 1.2MPa for 2 hours to obtain a mixed reaction product containing lye, sodium aluminate and dealuminated red mud, after the mixed reaction product is cooled to 100°C , take out the reaction kettle and heat-preserve and suction filter in an oven at 100°C, and separate the alkali solution containing sodium aluminate and the dealuminated red mud. At this time, A / S=0.49 in the dealuminated red mud composition (A is the weight percentage of alumina, S silicon oxide weight percent), the recovery rate of the alumina of Bayer process red mud is 68.79%.

[0030] The alkali solution (filter mother liquor) containing sodium aluminate obtained is put into th...

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Abstract

The invention relates to a method for reclaiming alumina and sodium oxide in red mud of Bayer process. The method comprises the following steps: carrying out leaching reaction of the red mud in 30 to 70 weight percent NaOH solution for 0.2 to 5 hours, according to the weight ratio of alkali solution to red mud being 4:1-8:1, at a leaching temperature between 180 and 250 DEG C, and under a pressure between 0.3 and 1.8MPa; obtaining alkali solution containing sodium aluminate and dealuminized red mud by filtration; crystallizing the alkali solution containing sodium aluminate at a temperature between 50 and 100 DEG C to obtain hydrated sodium aluminate macrocrystal and crystallized mother solution, and applying the crystallized mother solution in leaching reaction circularly; dissolving the hydrated sodium aluminate macrocrystal by water to return to Bayer process production, and obtaining alumina through desiliconization, seed separation and calcination; adding water and calcium oxide with the weight accounting for 5 to 20 percent of that of the dealuminized red mud in the dealuminized red mud to eliminate sodium at a temperature between 100 and 180 DEG C and a liquid-solid ratio ranging from 6:1 to 10:1; and after sodium elimination, the red mud is used for cement production, while the NaOH solution is used for leaching reaction. The method has the advantages of lower dissolution temperature and pressure and 90 percent dissolution rate of alumina.

Description

technical field [0001] The invention relates to the field of production methods of alumina and sodium oxide, in particular to a method for recycling alumina and sodium oxide in Bayer process red mud at low temperature and low pressure. Background technique [0002] At present, basic industries all over the world are facing global energy shortages, increasingly scarce resources, and more and more people's attention to environmental protection. For the alumina industry, these challenges are becoming more and more acute. [0003] my country's alumina production mainly uses insoluble diaspore bauxite as raw material. According to statistics, the ore with A / S>10 accounts for only 10%, the ore with A / S of 7-10 accounts for 20%, and the ore with A / S>10 accounts for 20%. The ore with / S of 4-7 accounts for more than 60%. High aluminum, high silicon, and low aluminum-silicon ratio are important characteristics of bauxite in my country. When using the pure Bayer process to treat...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01F7/02C01D1/02
Inventor 郑诗礼孙旺张亦飞钟莉张懿
Owner INST OF PROCESS ENG CHINESE ACAD OF SCI
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