Method for preparing high-purity alumina
AssigneeHMR GmbH
InventorJae Hoon Hu
Life of this patent
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Abstract
The present invention relates to a method for preparing high-purity aluminum, the method comprising: a mother liquor preparing step for preparing a mother liquor by dissolving and aging ordinary aluminum hydroxide; a refining step for adding pulp to absorb impurities from the prepared mother liquor after the mother liquor preparing step; and an obtaining step for obtaining high-purity alumina by adding a seed into the mother liquor and precipitating a precipitate, and filtering, washing, and recrystallizing the precipitate, and calcining the precipitate. Thus, the present invention enables an environmentally-friendly and low-cost preparation of high-purity alumina.
Claims12
A method for high-purity alumina, the method comprising:
- a mother liquor preparing step of preparing a mother liquor by dissolving and aging aluminum hydroxide;
- a refining step of adding pulp to absorb impurities from the prepared mother liquor, after the mother liquor preparing step to form refined mother liquor;
- and
- an obtaining step of obtaining high-purity alumina, after the refining step,
- wherein the obtaining step is a step of obtaining the high-purity alumina by adding a seed to the refined mother liquor to form a precipitate, filtering, washing and dissolving the precipitate, recrystallizing the dissolved precipitate by neutralizing the dissolved precipitate, again filtering and washing the recrystallized precipitate, mixing a small amount of aluminum fluoride (AlF3) with the washed recrystallized precipitate, and then calcining the mixed precipitate.
A method for high-purity alumina, the method comprising:
- a dissolving step of preparing a mother liquor by adding a caustic soda (NaOH) solution and aluminum hydroxide into a dissolution bath and dissolving the aluminum hydroxide;
- an aging step of aging impurities while slowly decreasing a temperature of the mother liquor dissolved through the dissolving step during a predetermined aging time;
- a refining step of adding and dispersing an absorbent made of pulp into the mother liquor aged through the aging step, thereby absorbing the impurities in the mother liquor into the absorbent;
- a first filtering step of separating the pulp having the impurities absorbed thereinto, filtering the mother liquor and then providing the filtered mother liquor to a precipitation bath, after the refining step;
- a precipitating step of precipitating aluminum hydroxide by adding an aluminum hydroxide seed into the mother liquor of the precipitation bath, after the first filtering step;
- a polarizing step of separating a precipitate having a small particle size and a precipitate having a large particle size, after the precipitating step;
- a second filtering step of filtering the mother liquor containing the precipitate having the large particle size in the polarizing step, thereby recycling the filtered mother liquor as the caustic soda solution;
- a recrystalizing step of washing the precipitate remaining in the second filtering step, dissolving aluminum hydroxide in an acid and then neutralizing the dissolved aluminum hydroxide using alkali, thereby recrystalizing the precipitate;
- a third filtering step of collecting the recrystalized precipitate in the recrystalizing step and filtering and washing the collected precipitate;
- and
- a calcining step of mixing aluminum fluoride (AlF3) with the collected precipitate washed in the third filtering step and then calcining the mixed precipitate at 1050° C. or more for 1 hour or more.
Dependencies are inferred from the claim text.