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A method for extracting alumina from fly ash with a sulfammonium salt mixed medium system

A technology of mixed media and sulfur-based ammonium salt, applied in the direction of alumina/aluminum hydroxide, etc., can solve the problems of large consumption of sulfur-based ammonium salt, difficult separation of impurities, difficulty in ammonia recovery, etc., to avoid high-temperature calcination and high energy consumption process, improving extraction efficiency, and the effect of efficient utilization

Active Publication Date: 2017-03-29
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

[0006] The technical problem to be solved in the content of the present invention is: to provide a method for extracting alumina from fly ash with a sulfammonium salt mixed medium system, and to effectively solve the energy consumption in the sintering or evaporation concentration process in the existing method of extracting alumina from fly ash high, impurity separation is difficult, and the consumption of sulfur-based ammonium salt is large, and ammonia recovery is difficult, so as to realize the efficient and clean extraction of alumina in fly ash

Method used

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  • A method for extracting alumina from fly ash with a sulfammonium salt mixed medium system
  • A method for extracting alumina from fly ash with a sulfammonium salt mixed medium system
  • A method for extracting alumina from fly ash with a sulfammonium salt mixed medium system

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Experimental program
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Embodiment 1

[0056] The fly ash of a coal-fired power plant selected in this embodiment has an alumina content of 47.58% and a silicon oxide content of 44.30%. The specific process is as follows:

[0057] 1) Mechanically pulverize and sieve the fly ash to a particle size smaller than 100 mesh;

[0058] 2) Prepare NH 4 + The concentration is 5mol / L, H + A mixed medium system of ammonium sulfate and sulfuric acid with a concentration of 15mol / L;

[0059] 3) According to the liquid-solid ratio of 10 / 3 (ml / g), add 33.3g of the fly ash obtained in step 1) and 100ml of the mixed medium solution obtained in step 2) into the closed reactor with stirring , carry out alumina leaching reaction;

[0060] 4) Heat the closed system in step 3) to 220°C, the pressure is about 0.25MPa, and react for 6h;

[0061] 5) Cool the system after the reaction in step 4) to 90°C, and filter to obtain the primary filtrate and primary filter residue;

[0062] 6) Cool the primary filtrate obtained in step 5) to 10...

Embodiment 2

[0071] The fly ash of a coal-fired power plant selected in this embodiment has an alumina content of 25.58% and a silicon oxide content of 67.12%. The specific process is as follows:

[0072] 1) Mechanically pulverize and sieve the fly ash to a particle size smaller than 200 mesh;

[0073] 2) Prepare NH 4 + The concentration is 20mol / L, H + A mixed medium system of ammonium sulfate and sulfuric acid with a concentration of 20mol / L;

[0074] 3) Add 50.0g of the fly ash obtained in step 1) and 100ml of the mixed medium solution obtained in step 2) into a closed reactor with stirring at a liquid-solid ratio of 10 / 2 (ml / g) , carry out alumina leaching reaction;

[0075] 4) Heat the closed system in step 3) to 240°C, the pressure is about 0.4MPa, and react for 0.5h;

[0076] 5) Cool the system after the reaction in step 4) to 95°C, and filter to obtain the primary filtrate and primary filter residue;

[0077] 6) Cool the primary filtrate obtained in step 5) to 15°C, a large a...

Embodiment 3

[0086] The fly ash of a coal-fired power plant selected in this embodiment has an alumina content of 32.29% and a silicon oxide content of 60.06%. The specific process is as follows:

[0087] 1) Mechanically pulverize and sieve the fly ash to a particle size smaller than 300 mesh;

[0088] 2) Prepare NH 4 + The concentration is 15mol / L, H + A mixed medium system of ammonium sulfate and sulfuric acid with a concentration of 25mol / L;

[0089] 3) According to the liquid-solid ratio of 10 / 4 (ml / g), add 25.0g of the fly ash obtained in step 1) and 100ml of the mixed medium solution obtained in step 2) into the closed reactor with stirring , carry out alumina leaching reaction;

[0090] 4) Heat the closed system in step 3) to 120°C, the pressure is about 0.2MPa, and react for 6h;

[0091] 5) Cool the system after the reaction in step 4) to 75°C, and filter to obtain the primary filtrate and primary filter residue;

[0092] 6) Cool the primary filtrate obtained in step 5) to 20...

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Abstract

The invention relates to a method for extracting alumina from fly ash through a sulfo ammonium salt mixing medium system. The method comprises: adopting solid waste fly ash discharged from coal-fired power plant or boiler as a raw material, and carrying out strengthening leaching in a sulfo ammonium salt mixing medium system at a high temperature of 120-240 DEG C, wherein the leaching time is 0.5-6 h; maintaining the system at a temperature of 75-95 DEG C after the leaching, and filtering to obtain the primary filtrate and the primary filtration residue; cooling the primary filtrate to a temperature of 10-30 DEG C by using the characteristic of the large change of the ammonium aluminum sulfate solubility along with the temperature change so as to precipitate the ammonium aluminum sulfate solid; washing the primary filtration residue at a temperature of 85-95 DEG C, and filtering to obtain the secondary filtrate and the secondary filtration residue; carrying out evaporation concentration on the secondary filtrate, and cooling to a temperature of 10-30 DEG C so as to precipitate the ammonium aluminum sulfate solid; and carrying out sectional high-temperature calcination (600-800 DEG C and 1000-1200 DEG C) on the obtained ammonium aluminum sulfate solid so as to obtain the white alumina powder, and recovering the sulfo ammonium salt mixing medium. With the method of the present invention, the efficient cleaning extraction of the alumina from the fly ash can be achieved, the impurity is easily removed, and good economic benefits and broad industrial application prospects are provided.

Description

technical field [0001] The invention belongs to the field of resource utilization of bulk solid waste, and particularly relates to a method of using fly ash discharged from coal-fired power plants or coal-fired boilers as a raw material, and using a sulfur-based ammonium salt mixed medium system to leach the fly ash, thereby efficiently extracting the fly ash. A method of alumina in coal ash. Background technique [0002] Fly ash is the fine ash collected from the flue gas of coal combustion. The annual discharge of fly ash in my country has reached 500 million tons, and the cumulative amount has reached 3.5 billion tons, of which the discharge of fly ash from coal-fired power plants is the largest. The fly ash collected by coal-fired power plants is currently mainly stored in ash yards and piled up in the open air. If it is not disposed of in time or improperly, it will not only occupy a large amount of land, but also cause serious harm to the environment and even human su...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C01F7/02
Inventor 李会泉许德华包炜军王晨晔孙振华回俊博
Owner INST OF PROCESS ENG CHINESE ACAD OF SCI
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