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

[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...

[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.

[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.