Preparation of Battery-Grade FePO·2HO Using the Stripping Solution Generated from Resource Recycling of Bauxite Residue.

A novel process for the high-value-use of iron from bauxite residue was proposed in this work. The process was trying to use the iron-containing stripping solution generated during resource recycling of bauxite residue to produce battery-grade FePO·2HO product. Thermodynamics calculation indicates that Fe and P in the stripping solution mainly existed in the form of FeHPO, and the theoretical pH for the conversion reaction from FePO·2HO to Fe(OH) was 1.72. The optimal condition for the synthesis of FePO·2HO using the stripping solution was determined as: reaction pH of 0.8, reaction temperature of 90°C, Fe/P ratio of 1, and reaction time of 24 h. XRD result showed that the synthesized FePO·2HO was well-crystallized and perfectly matched with the characteristic peaks of FePO·2HO. Moreover, all the parameters of the synthesized iron phosphate meet the quality requirements of battery precursor.