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Method for firstly extracting silicon and secondly extracting aluminum from fly ash

A technology of fly ash and sintering method, which is applied in the preparation of silicon oxide, aluminum oxide/hydroxide, etc., can solve uneconomical problems, achieve low product cost, simple process flow, and increase the value of resource utilization

Active Publication Date: 2008-02-20
PINGSHUO INDAL
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the Bayer process requires a relatively high aluminum-silicon ratio of raw ore, which needs to be ≥ 7. For bauxite with a ratio of 3 2 o 3 It is uneconomical, and it is necessary to sinter the ore powder with alkali and calcium, or use other complicated methods to extract

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0021] 100kg average particle size ≤ 20μm, Al 2 o 3 After the fly ash with content ≥40% is dried below 400°C, move it into a reaction kettle, add 150L of 80% NaOH solution, stir and soak at 115-125°C for 1 hour, then add 200L of water or dilute lye to dilute Filter to get SiO 2 310L of sodium silicate solution with a concentration of 118g / L and 65kg of alkali leaching residue with an aluminum-silicon ratio of about 3.25.

[0022] After diluting the 118g / L sodium silicate solution to 60g / L, move it to the carbon separator, and introduce CO 2 Gas, stir the carbon at 70-85°C to pH = 9, stop the carbon, filter and separate, and get about 35kg of white carbon black, its SiO 2 Content > 98.5%.

[0023] The carbonized filtrate is mixed with CaO, causticized at 75°C, then concentrated by evaporation to make its concentration reach the concentration used in alkali leaching, and then returned to the alkali leaching process for recycling.

[0024] Alkali leaching residue after silic...

Embodiment 2

[0028] The average particle size of 100kg dried at 200°C is ≤20μm, Al 2 o 3 Put the fly ash with 41% content into the reaction kettle, add 160L of 70% NaOH solution, stir and soak at 120°C for 2 hours, then add 200L of water or dilute lye to dilute and filter to obtain SiO 2 300L of sodium silicate solution with a concentration of 113g / L and 66kg of alkali leaching residue with an aluminum-silicon ratio ≥ 3.

[0029] The subsequent treatment of the sodium silicate solution and the alkali leaching residue is the same as in Example 1.

Embodiment 3

[0031]Take 100kg of fly ash with a particle size of ≤20μm, dry it at 850°C and remove C, then transfer it to an alkaline leaching kettle, add 220L of 60% NaOH solution, stir and soak at 125°C for 2.5h, and dilute with 200L of dilute lye Filter to get SiO 2 350L of sodium silicate solution with a content of 110g / L, and about 65kg of alkali leaching residue with an aluminum-silicon ratio>4.

[0032] The subsequent treatment of the sodium silicate solution and the alkali leaching residue is the same as in Example 1.

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Abstract

The invention relates to a method to withdraw silicon and aluminum in sequence from coal ash; a NaOH solution with a mass concentration larger than 40 percent is used for leaching the coal ash, the silicon of the coal ash is dissolved in the form of sodium silicate, and after being separated, sodium silicate solutions and alkaline leaching residues with a ratio between aluminum and silicone more than or equal to 2 are produced; the dissolved sodium silicate solution is condensed into sodium silicate solutions of different concentrations, or used for preparing white carbon through a carbonation method; the alkaline residues are used for producing Al(OH)3 through a sodalime sintering method or limestone sintering method and further producing Al2O3, and the residues after the aluminum being extracted are made into stuff or used for producing concrete. The invention breakthroughs the original idea of directly extracting Al2O3 from the coal ash, and adopts the wholly novel technical route of extracting silicon first and aluminum secondly, thereby enhancing the aluminum silicon ratio of the alkali leached residues, simplifying the technique of extracting Al2O3, and increasing the extracting rate of aluminum from the coal ash.

Description

technical field [0001] The invention belongs to the resource comprehensive utilization of fly ash, and relates to a method for extracting silicon dioxide and alumina from fly ash, in particular to a method for extracting silicon dioxide from fly ash to make the remaining ash The aluminum-silicon ratio of the slag is ≥ 2, and the lime or soda lime sintering method is used to produce metallurgical grade alumina, and the residue is used as a filler or a method for preparing cement. Background technique [0002] A large amount of fly ash emitted by coal-fired power plants has caused serious pollution and damage to the surrounding agricultural production and natural ecology. The comprehensive utilization of fly ash has become an urgent problem to be solved. [0003] Fly ash is also a mineral resource. Fly ash generally contains Al 2 o 3 About 15-40%, containing SiO 2 Most of them are above 40%, and the fly ash in some places contains Al 2 o 3 Above 40%, containing SiO 2 Ab...

Claims

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Application Information

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IPC IPC(8): C01B33/113C01F7/30
Inventor 秦晋国顾松青
Owner PINGSHUO INDAL
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