Alumina Adsorbent Modified And Fluorine Removal Performance Research

In the process of hydrometallurgy,it's very negative for electrolytic process with high fluorine ion content in zinc sulfate solution and the industrial production cannot be normal.At present,the fluorine content requirement of zinc sulfate electrolyte is less than 50mg/L,and the fluoride removal methods that are applied currently have defects in different degrees.Therefore,it has become a research focus in the smelting industry that to explore efficient and economical fluorine removal methods and to solve the problem of fluorine removal in the zinc sulfate solution effectively.In this paper,the author learned that adsorption method has little effect on the original process and has some advantages than traditional method through the literature and investigation,such as widely adapt to conditions,convenient operation and low cost,so we selected the adsorption method for fluorine removal.It is able to meet the needs of smelting enterprises through the selection and modification of adsorbent.We identified three adsorbents that have good de-fluoridation effect as the research object by comparing the various adsorbents de-fluoridation test,including natural zeolite,bentonite and aluminum hydroxide.Adsorption performance for three kinds of adsorbent after the modification to fluorine ion was studied by static experiments.X-ray diffraction(XRD),X-ray absorption spectroscopy(EDX),infrared spectra(FTIR)and specific surface area(BET)were used to characterize structures and properties of three kinds of adsorbent.The impact of the amount of adsorbent,adsorption time,temperature and p H in adsorption performance were studied.Moreover,the adsorption model and dynamics mechanism for the de-fluoridation process were studied.There is a different de-fluoridation effect in the actual solution and the simulation solution.So we explored and analyzed thepossible influencing factors through the experimental research.Natural zeolite and bentonite are modified by load lanthanum and aluminum hydroxide is modified by roasting.The results show that the adsorption capacity of three kinds of adsorbent is improved after modification.We can know that the de-fluoridation effect of modified aluminum hydroxide is the best in the actual solution by de-fluoridation test.The best de-fluoridation conditions of modified aluminum hydroxide as follows: the content of 5?10 g/L,temperature is 40 ?,p H is 4.The adsorption of the modified aluminum hydroxide to fluorine ion is conducted by Freundlich adsorption model.In the process of adsorption,physical adsorption occupied a dominant position.The adsorption rate for the fluoride ion on the modified aluminum hydroxide is external diffusion.The main reason of impact de-fluoridation effect is complexation with F and Zn ions,the content of other ions is very few and it is almost no impact to de-fluoridation.In the actual solution,the amount of free fluorine contained less than simulation solution,so the maximum adsorption capacity of adsorbent is difficult to achieve and adsorption effect is inadequate in the actual solution.