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Method for linked preparation of sodium aluminate and production of silica-based material by means of high-alumina fly ash low-temperature liquid-phase alkali dissolving

A high-alumina fly ash, low-temperature liquid phase technology, applied in the preparation of alkali metal aluminate/alumina/aluminum hydroxide, silicon oxide, silicon dioxide, etc., can solve the problems of high energy consumption, complicated operation, etc. Achieve the effect of high added value of products, fewer operation steps and less slag amount

Active Publication Date: 2013-09-18
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

[0007] The purpose of the present invention is to provide a new method for the comprehensive utilization of high-alumina fly ash in view of the shortcomings of the above methods, such as complicated operation and high energy consumption, and the products are activated silica, sodium aluminate and desodiumized slag

Method used

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  • Method for linked preparation of sodium aluminate and production of silica-based material by means of high-alumina fly ash low-temperature liquid-phase alkali dissolving
  • Method for linked preparation of sodium aluminate and production of silica-based material by means of high-alumina fly ash low-temperature liquid-phase alkali dissolving
  • Method for linked preparation of sodium aluminate and production of silica-based material by means of high-alumina fly ash low-temperature liquid-phase alkali dissolving

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Experimental program
Comparison scheme
Effect test

Embodiment 1

[0031] 1) Use dry magnetic separator to separate iron oxide from 1# high alumina fly ash. The magnetic field strength is 1000-1300 Oersted, and the content of iron oxide in the obtained iron concentrate is close to 45%.

[0032] 2) The high-aluminum fly ash after iron removal and 10% sodium hydroxide solution are uniformly mixed in a ratio of 1:2, put into a high-pressure reactor, and react at 70°C for 0.5h. Filter and separate the reaction product to obtain desiliconization liquid and desiliconization fly ash, SiO 2 The removal rate is 23%.

[0033] 3) The desiliconization solution is kept at 60°C, and 50% (volume concentration) of CO is introduced 2 , with the pH of the solution = 7.5 as the end point. Filter the separated silicic acid colloid, wash and dry to obtain active SiO 2 .

[0034] 4) Desiliconized fly ash, Ca(OH) 2 Mix it with NaOH solution according to a certain ratio, and add it to the autoclave. Among them, NaOH concentration is 45%, Ca(OH) 2 The ratio o...

Embodiment 2

[0039] 1) The magnetic separation process is the same as in Example 1.

[0040] 2) Mix the iron-removing fly ash with 30% sodium hydroxide solution at a ratio of 1:5, add to the reactor, and react at 130°C for 3 hours. The reaction product is separated by filtration to obtain desiliconization liquid and desiliconization fly ash. Among them, SiO 2 The removal rate is 38%.

[0041] 3) The desiliconization solution is kept at 90°C, and 100% (volume concentration) of CO is introduced 2 , with the pH of the solution = 10.5 as the end point. The separated silicic acid colloid was filtered, washed and dried to obtain active SiO 2 .

[0042] 4) Desiliconized fly ash, Ca(OH)2 Mix it with NaOH solution according to a certain ratio, and add it to the autoclave. Among them, NaOH concentration is 65%, Ca(OH) 2 The ratio of calcium to silicon in the desiliconized fly ash is 1.2:1 (molar ratio), the reaction temperature is 300°C, and the reaction time is 3h. After the reaction was co...

Embodiment 3

[0047] 1) The magnetic separation process is the same as in Example 1.

[0048] 2) Mix the iron-removing fly ash with 15% sodium hydroxide solution evenly at a ratio of 1:3, add to the reactor, and react at 110°C for 1.5h. The reaction product is separated by filtration to obtain desiliconization liquid and desiliconization fly ash. Among them, SiO 2 The removal rate is 34%.

[0049] 3) The desiliconization solution is kept at 90°C, and 85% (volume concentration) of CO is introduced 2 , with the pH of the solution = 9.5 as the end point. The separated silicic acid colloid was filtered, washed and dried to obtain active SiO 2 .

[0050] 4) Desiliconized fly ash, Ca(OH) 2 Mix it with NaOH solution according to a certain ratio, and add it to the autoclave. Among them, NaOH concentration is 55%, Ca(OH) 2 The ratio of calcium to silicon in desiliconized fly ash is 0.8:1 (molar ratio), the reaction temperature is 280°C, and the reaction time is 1.5h. After the reaction was ...

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Abstract

The invention discloses a method for linked preparation of sodium aluminate and production of silica-based material by means of high-alumina fly ash low-temperature liquid-phase alkali dissolving. The method comprises the following steps of: 1) obtaining fine iron ore sand and iron-removed fly ash by separation; (2) reacting the iron-removed fly ash with a dilute NaOH solution to obtain desiliconized fly ash and a desilication solution; (3) reacting the desiliconized fly ash with calcium hydroxide and the NaOH solution to obtain a crude solution of sodium aluminate and calcium silicate slag; (4) diluting the crude solution of sodium aluminate, adding calcium oxide into the diluted solution, and desiliconizing the resulting solution to obtain a refined solution of sodium aluminate; (5) adding a sodium aluminate crystal into the refined solution of sodium aluminate, and decomposing the seed crystal to obtain a sodium aluminate crystal hydrate and a seed precipitation mother solution; (6) introducing CO2 into the desilication solution for carbonation to obtain active silicon dioxide; (7) reacting calcium silicate slag with water to obtain sodium-removed slag. The method disclosed by the invention is wide in raw material resources, mild in reaction condition, less in operation step, capable of fully utilizing the raw materials, less in slag amount, high in product added value, and wide in purpose.

Description

technical field [0001] The invention relates to the field of solid waste utilization, in particular to a method for preparing sodium aluminate and co-producing silicon-based materials by utilizing high-aluminum fly ash in a low-temperature liquid-phase alkali dissolution method. Background technique [0002] Fly ash is the fine ash collected by pulverized coal furnaces or fluidized bed boiler dust collectors in large and medium-sized coal-fired power plants. It is one of the solid wastes with the largest emissions in my country. 2 o 3 The content is relatively high, generally more than 30%. my country's fly ash is mainly used as cement and concrete, but the utilization rate is low, and most of the fly ash is still piled up and discarded, which wastes resources and pollutes the environment. Compared with ordinary fly ash, high-alumina fly ash has higher alumina content, and its aluminum-silicon ratio is close to that of low-grade bauxite, which is suitable for resource util...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01F7/04C01B33/12B09B3/00
Inventor 李会泉回俊博李少鹏孙振华包炜军李勇辉
Owner INST OF PROCESS ENG CHINESE ACAD OF SCI
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