Method for preparing low-sodium and high-activity aluminum hydroxide seed crystal by Bayer process
A technology of aluminum hydroxide and high activity, applied in the field of alumina, can solve problems such as low whiteness, high sodium content, imperfect grain structure, etc., and achieve the effect of excellent decomposition rate and excellent dispersion performance
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Embodiment 1
[0064] S1. Add lime milk to the sodium aluminate solution overflowing from the second tank at the end of settling, the dosing ratio is 15g / L, wherein the available calcium of lime milk reaches more than 90%, and the residence time is 2 hours. After the causticization process is completed , which is pumped to a vertical leaf filter for filtration to obtain semen, in which the A / S value is ≥180 and the mass concentration of floating matter is ≤0.015g / L;
[0065] S2. The temperature of the semen is raised to 72°C, and then the temperature is gradually lowered to 52°C with an isothermal difference of 2.5°C to obtain the first slurry;
[0066] S3, aging the first slurry at a temperature of 43° C. for 18 hours to obtain an aluminum hydroxide seed crystal slurry;
[0067] The temperature-lowering treatment and the aging are carried out under stirring conditions with a rotation speed of 450 r / min.
[0068] S4. Mix the aluminum hydroxide seed crystal slurry with the semen at a mass ra...
Embodiment 2
[0070] S1. Add milk of lime to the sodium aluminate solution overflowing from the second tank at the end of settling, the dosing ratio is 5g / L, the available calcium of the milk of lime reaches more than 90%, and the residence time is 1.5 hours. After the causticization process is completed , which is pumped to a vertical leaf filter for filtration to obtain semen, in which the A / S value is ≥180 and the mass concentration of floating matter is ≤0.015g / L;
[0071] S2. The temperature of the semen is raised to 70°C, and after the temperature is raised, the temperature is gradually lowered to 50°C with an isothermal difference of 2°C to obtain the first slurry;
[0072] S3, aging the first slurry at a temperature of 40° C. for 16 hours to obtain an aluminum hydroxide seed crystal slurry;
[0073] The temperature-lowering treatment and the aging are carried out under stirring conditions with a rotation speed of 400 r / min.
[0074] S4. Mix the aluminum hydroxide seed crystal slurr...
Embodiment 3
[0076] S1. Add milk of lime to the sodium aluminate solution overflowing from the second tank at the end of settling. , which is pumped to a vertical leaf filter for filtration to obtain semen, in which the A / S value is ≥180 and the mass concentration of floating matter is ≤0.015g / L;
[0077] S2. The temperature of the semen is raised to 74°C, and after the temperature is raised, the temperature is gradually lowered to 54°C with an isothermal difference of 3°C to obtain the first slurry;
[0078] S3, aging the first slurry at a temperature of 45° C. for 20 hours to obtain an aluminum hydroxide seed crystal slurry;
[0079] The temperature-lowering treatment and the aging are carried out under stirring conditions with a rotation speed of 500 r / min.
[0080] S4. Mix the aluminum hydroxide seed crystal slurry with the semen at a mass ratio of 1:6.5, decompose in one stage, and obtain a solid through solid-liquid separation, wash and dry the solid to obtain low-sodium high-activi...
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