硫酸亚铁的重结晶对其水热法制备α-Fe_2O_3粒子的影响

Effect of recrystallization on formation of α-Fe_2O_3 particles prepared from ferrous sulphate by hydrothermal process

以钛白副产物硫酸亚铁为原料,采用重结晶法对其除杂后,得到精制硫酸亚铁与氨水反应制备Fe（OH）3胶体为前驱体,经水热反应合成α-Fe2O3粒子。考察重结晶对硫酸亚铁的杂质去除及其水热法制备α-Fe2O3粒子的影响。采用电感耦合等离子体光谱仪分析硫酸亚铁和水热产物中的杂质元素含量,通过X线衍射仪、扫描电镜和激光粒度仪分析水热产物物相、形貌和粒径。研究结果表明：当结晶温度在0~30℃时,随着温度的升高,硫酸亚铁中杂质Ti,Zn和Al的去除率变化不大,杂质Mg和Mn的去除率略有增大,经过2次重结晶,Mg,Ti,Mn,Zn和Al的最大去除率分别可达到60.15%,94.87%,70.44%,50.90%和71.36%;随着结晶数的增加,所得水热法α-Fe2O3产品纯度更高、杂质含量更低,颗粒结晶更完整、粒径越小、粒径分布范围越窄,结晶数为0,1和2时所得球形α-Fe2O3粒子的纯度分别为96.32%,98.40%和98.80%,它们的中位粒径分别为0.66,0.62和0.58？m。

Iron oxide particles Were synthesized by hydrothermal process, using ferric hydroxide gel as precursor. The precursor was prepared by the reaction of ammonia and refined ferrous sulfate which was obtained by recrystallization from a byproduct of TiO2 industry. The effects of recrystallization on impurities removal of ferrous sulphate and formation of α-Fe2O3 particles synthesized from ferrous sulphate by hydrothermal process were studied. The impurity elements of ferrous sulphate and iron oxide samples were analyzed by inductively coupled plasma optical emission spectrometer （ICP-OES）, and the phase, shape and particle size of the synthesized iron oxide were characterized by X-ray diffraction （XRD）, scanning electron microscope （SEM） and laser particle size analyzer （LPSA） respectively. The results show that ferrous sulphate is purified by recrystallization method. With the increase of crystallization temperature, when it is in the range of 0-30 ~C, the removal rates of impurity Ti, Zn and A1 change little and those of impurity Mg and Mn increase slightly. After double recrystallization, the maximum removal rates of impurity Mg, Ti, Mn, Zn and A1 reach 60.15%, 94.87%, 70.44%, 50.90% and 71.36%, respectively. With the increase of crystallization times, α-Fe2O3 particles with higher purity, lower impurity content, better crystallization, smaller particle size and narrower particle size distribution are obtained. The Fe203 purity of spherical iron oxide particles prepared at 0, 1 and 2 times crystallization are 96.32%, 98.40% and 98.80%, respectively, and the median particle sizes are 0.66, 0.62 and 0.58μm, respectively.