Method for aluminum-enhanced dealkalization of red mud and separation and recovery of aluminum and iron
The present invention discloses a method for aluminum-enhanced dealkalization of red mud and separation and recovery of aluminum and iron. The method includes: dissolving red mud in water, introducing excessive SO 2 , introducing O 2 for aeration, and refluxing part of alkaline leachate after filtering; when pH of a red mud mixture decreases to below 3, washing and filtering the red mud mixture, adding NaOH to acidic leachate to adjust its pH to a strongly alkaline level, aging and filtering the leachate, treating filter residue to recover Fe 2 O 3 , and refluxing part of alkaline leachate after filtering to the red mud mixture; and adjusting pH of the remaining alkaline leachate after filtering to a weakly acidic level, and conducting filtering to recover aluminum.
1. A method for aluminum-enhanced dealkalization of red mud and separation and recovery of aluminum and iron, comprising the following steps:
S1: grinding red mud and dissolving the red mud in slurry liquid, wherein the slurry liquid is water and/or alkaline leachate obtained after filtering; uniformly stirring the mixture to obtain red mud slurry; introducing SO 2 and O 2 for aeration oxidation to obtain a red mud mixture; and filtering the red mud mixture to obtain dealkalized red mud and acidic leachate; and
S2: adjusting pH of the acidic leachate obtained by filtering to a strongly alkaline level to obtain alkaline leachate; filtering the alkaline leachate to obtain alkaline leachate after filtering and filter residue; drying and sintering the filter residue, washing an obtained product with water, and conducting drying to recover Fe 2 O 3 ; returning ⅕-½ of the alkaline leachate after filtering to step (1) as the slurry liquid; and adjusting pH of the remaining alkaline leachate after filtering to a weakly acidic level, and conducting filtering to separate and recover Al(OH) 3 .
2. The method for aluminum-enhanced dealkalization of red mud and separation and recovery of aluminum and iron according to claim 1 , wherein in step (1), the red mud is ground into a particle size of 100-200 meshes.
3. The method for aluminum-enhanced dealkalization of red mud and separation and recovery of aluminum and iron according to claim 1 , wherein a liquid-solid ratio of the red mud slurry is 7:1.
4. The method for aluminum-enhanced dealkalization of red mud and separation and recovery of aluminum and iron according to claim 1 , wherein in step (1), SO 2 is introduced by allowing the SO 2 gas to be in reverse contact with the red mud slurry for absorption.
5. The method for aluminum-enhanced dealkalization of red mud and separation and recovery of aluminum and iron according to claim 1 , wherein in step (1), the introduction amount of the SO 2 gas is 1-12 L per m 3 of the red mud slurry.
6. The method for aluminum-enhanced dealkalization of red mud and separation and recovery of aluminum and iron according to claim 1 , wherein in step (1), an introduction volume ratio of the O 2 gas to the SO 2 gas is 1:(1-5).
7. The method for aluminum-enhanced dealkalization of red mud and separation and recovery of aluminum and iron according to claim 1 , wherein washing needs to be conducted 3-8 times after filtering.
8. The method for aluminum-enhanced dealkalization of red mud and separation and recovery of aluminum and iron according to claim 1 , wherein in step (1), pH of the red mud mixture needs to be below 3.
9. The method for aluminum-enhanced dealkalization of red mud and separation and recovery of aluminum and iron according to claim 1 , wherein in step (2), pH of the alkaline leachate needs to be above 13.
10. The method for aluminum-enhanced dealkalization of red mud and separation and recovery of aluminum and iron according to claim 1 , wherein in step (2), the weak acidity means that pH needs to be above 4.7.