Study on Efficient Fluoride Removal from Crude Sodium Tungstate Solution by Hydroxyapatite AITranslate

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Chinese Library Classification Number:TF111[冶金工程]

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The crude sodium tungstate solution obtained from scheelite decomposition contains a certain concentration of fluorine,which easily leads to the concentration of fluoride in smelting wastewater exceeding the national discharge standard.In this study,hydroxyapatite was used as a fluoride-removing reagent,which reacted with fluorine ions to form calcium fluorophosphate precipitate with very low solubility,so as to deeply remove fluoride from the crude sodium tungstate solution.The effects of hydroxyapatite dosage,reaction temperature,solution pH value,reaction time and initial fluoride concentration on the fluoride removal were investigated.The experimental results show that hydroxyapatite has an excellent fluoride-removing performance in the crude sodium tungstate solution.Under the conditions where the fluoride concentration is 0.5~5.5 g/L,the dosage of hydroxyapatite is 1.8 times of the theoretical amount,reaction temperature is 80℃,the solution pH value is 10.5,and reaction time is 60 min,the fluoride removal rate is more than 96%,and the tungsten loss rate in the precipitated slag is less than 0.27%,thereby realizing the high-efficiency removal of fluoride with low tungsten loss.After fluoride removal,the crude sodium tungstate solution is subjected to subsequent ion exchange treatment,and the fluoride concentration in the discharged smelting wastewater meets the national discharge standard.