关键词: 磷酸铁, 磷铁渣, 沉淀, 结晶, 溶解, 纳米, 制备

Abstract:

Ferro-phosphorus was used as the iron source and the phosphorus source and the ferro-phosphorus was dissolved in the mixture of nitric acid and sulfuric acid, and battery-grade nano-iron phosphate was prepared by precipitation method. The influence of the concentration of nitric acid, the reaction time and temperature on the dissolving rate of ferro-phosphorus was studied. The effects of the ratio of iron and phosphorus, reacting temperature and pH on the performance of the FePO₄ were also explored. The crystal morphology, structure and chemical composition of the prepared nanoscale iron(Ⅲ) phosphate were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), thermogravimetric, differential scanning calorimetry (TG-DSC), infrared spectrometer, and inductively coupled plasma atomic emission spectrometer(ICP-AES). Experimental results show that the optimum experimental conditions for the dissolving of ferro-phosphorus areas follows: nitric acid concentration 1.5mol/L, reaction time 4h, reaction temperature 90℃, under which the dissolution rate of iron phosphate is 95.1%. The optimal conditions for the preparation of iron phosphate are: iron-phosphorus ratio 1∶1, reaction temperature 60℃, reaction pH 1.0. XRD and SEM analysis showed that the prepared FePO₄ had high crystallinity, and regular morphology, uniform particle dispersion, its primary particle size is around 100nm. The iron and phosphorus content test shows that the molar ratio of iron to phosphorus was 0.97. The content of impurity elements meets the requirement of battery grade FePO₄ precursor.

Key words: iron(Ⅲ) phosphate, ferro-phosphorus, precipitation, crystallization, dissolution, nano, preparation