二次铝灰中氟离子湿法去除机制的研究

Study on Wet Removal Mechanism of Fluoride Ion from Secondary Aluminum Ash

探索了铝灰常温常压下湿法脱氟的可行性。通过对二次铝灰的XRD分析,判断氟元素可能的来源为氟铝酸铵和六氟铝酸钠。对照实验表明,铝灰的水溶液中无氟离子溶出,判断氢氧化铝对氟离子溶解有一定的影响。通过研究pH对氢氧化铝形态的影响和氢氟酸电离平衡常数的计算,表明pH<5或pH>8且有适量的铝离子条件下,氟离子能溶解于水中。验证实验表明,pH=3的三氯化铝的路易斯酸水溶液能高效溶解铝灰中的氟元素。

At present,the mainstream aluminum ash defluorination at home and abroad is a high-temperature dry method,and this study explores the feasibility of aluminum ash removed fluorine at room temperature and atmospheric pressure with wet process.Through the XRD analysis of secondary aluminum ash,the possible sources of fluorine elements were ammonium fluorinate and sodium hexafluoroaluminate.The control experimental results show that there is no dissolution of fluorine ions in the general aqueous solution of aluminum ash,and it is judged that aluminum hydroxide has a certain effect on the dissolution of fluorine ions.By studying the effect of pH on the morphology of aluminum hydroxide and the calculation of the ionization equilibrium constant of hydrofluoric acid,the results show that under the condition of pH<5 or pH>8 and an appropriate amount of aluminum ions,fluoride ions can be dissolved in water,and the experimental results show that the Louis acid aqueous solution of pH=3 aluminum trichloride can efficiently dissolve the fluorine element in aluminum ash.