Experimental Research on Fluoride Removal with Zirconia-Based Reagent Combined with Amorphous Aluminum Hydroxide
An experimental study was carried out on fluoride removal from the wastewater after acid leaching process in one enterprise.In the experiment,zirconia was used in the 1st-stage reaction and amorphous aluminum hydroxide was adopted in the 2nd-stage reaction for fluoride removal,and effects of reaction temperature,reaction time and adding amount of zirconia-based reagent on the fluoride removal effect were explored.It is found that both higher temperature and longer reaction time can promote fluoride reduction effect of fluoride removing reagent.1st-stage reaction ran for 50 min at 75 ℃ with an addition of 50 g/L zirconia-based reagent,the fluoride reduction rate was up to 96％and fluoride mass concentration in the wastewater was reduced from 600 mg/L to 25 mg/L.After that,2nd-stage reaction at 70 ℃ ran for 60 min,by adding 5 g/L amorphous aluminum hydroxide,the fluoride mass concentration in the wastewater was down from 25 mg/L to 6.5 mg/L.It is shown that the residue left after fluoride removal process has a good crystal structure and obvious diffraction peak.XRD analysis shows that Na3AlF6 is the main component in the residue.
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