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

摘要：

以磷铁废渣为原料提供磷源和铁源，用硝酸和硫酸混合溶液浸出磷铁渣中的铁和磷元素，并通过沉淀法制备电池级纳米磷酸铁。探究了硝酸浓度、反应时间、反应温度对磷铁渣溶解率的影响，并研究了反应过程中铁磷比、温度和pH对制备的磷酸铁性能影响。利用X衍射分析仪、扫描电子显微镜、热重分析仪、红外光谱仪和电感耦合等离子体发射光谱仪等分析手段对磷酸铁的形貌、晶体结构与化学成分进行了表征。实验结果表明，磷铁渣浸出最佳的实验条件为：硝酸浓度1.5mol/L，反应时间4h，反应温度90℃，此条件下磷铁的溶解率为95.11%；磷酸铁制备过程中的最佳实验条件为：铁磷比1∶1，反应温度60℃，反应pH=1.0，所制备的FePO₄结晶度高，颗粒形貌规整，分散均匀，一次颗粒粒径为100～200nm，铁磷摩尔比为0.97，杂质元素含量符合电池级磷酸铁的要求。

关键词: 磷酸铁, 磷铁渣, 沉淀, 结晶, 溶解, 纳米, 制备