Reaserch On Reduction Behavior Of Iron Ion In Digestion Liquor Of FeTiO₃by Electrochemical Methods

Domestic and overseas resources of titanium, genetic types of titanium deposit and the beneficiation methods of ilmenite were reviewed in this thesis. The distribution and processing methods of ilmenite were found out. In recent years, as an energy-saving and environment-friendly process, alkali fusion processing of ilmenite has many advantages.Titanium resources is enriched in Pan-Xi Region of China, where is the largest base of producing Ti material in China. In order to realize comprehensive utilization of ilmenite in Pan-Xi Region and provide effective guidance to the separation of iron and titanium, FeTiO3was synthesized, which is the main component of ilmenite. The digestion liquor is gained after the process of NaOH alkali activation at600℃and acid leaching by sulfuric acid, the main component of which is Fe2(SO4)3and TiOSO4In order to effectively achieve the separation of iron and titanium, Fe(Ⅲ) need reduce to Fe(Ⅱ), then adjust the pH value, and iron ions were precipitated in the form of Fe(OH)2. Titanyl sulfate solution was concentrated and calcined to synthesize rutile. In order to electrochemically reduce Fe(Ⅲ) to Fe(Ⅱ) priorly in the FeTiO3digestion liquor, the reduction behavior of Fe(Ⅲ) is investigated by electrochemical method in this thesis. The results are the foundations of the further separation of iron and titanium.In this thesis, the electrochemical reduction behaviors of Fe(Ⅲ)/Fe(Ⅱ) and Ti(IV)/Ti(Ⅲ) in the FeTiO3digestion liquor have been respectively studied by cyclic voltammetry, AC impedance spectroscopy and rotating disk electrode measurements. The effect of temperature, the concentration of FeTiO3digestion liquor, the concentration of Fe(Ⅲ) and the concentration of sulfuric acid in the leaching process have been studied respectively.The experimental results showed that:in the FeTiO3digestion liquor, with increasing temperature,increasing concentration of FeTiO3digestion liquor, decreasing concentration of Fe(Ⅲ), decreasing concentration of sulfuric acid in the leaching process respectively, Fe(Ⅲ)/Fe(Ⅱ) and Ti(Ⅳ)/Ti(Ⅲ) reduction peak potential difference gradually increased, which indicated that Fe(Ⅲ) can be reduced to Fe(Ⅱ) preferentially; with increasing temperature, decreasing concentration of sulfuric acid in the leaching process respectively, the polarized impedance of the electrochemical reduction reaction of Fe(Ⅱ)/Fe(Ⅱ) decreased, and the speed of reduction reaction of Fe(Ⅲ)/Fe(Ⅱ) increased. It showed that Fe(Ⅲ) can be priorly reduced to Fe(Ⅱ) by electrochemical method, thus achieving the ultimate separation of iron and titanium by adjusting the pH value. The correlation analysis showed that Fe(Ⅲ)/Fe(Ⅱ) in the FeTiO3digestion liquor was a quasi-reversible process under mixed control of electrochemical reaction and diffusion. The diffusion coefficient of Fe(Ⅲ) is2.5×10-7cm2·s-1.