Chenyang Xu,Jianliang Zhang,Zhengjian Liu,Anjun Xu,Yaozu Wang,Liming Ma,Chuanhui Li
In order to study the change of each phase and the influence of single oxide during the consolidation of pellets. A systematic thermodynamic calculation was carried out through the phase diagram to study the influence of five oxides (CaO, SiO 2 , Fe 2 O 3 , Al 2 O 3 and MgO) on the phase equilibrium of the hematite pellet system. The results show that the content of CaO has the most significant effect on the content of liquid phase and SPINA. There are critical values for the influence of SiO 2 and CaO on the Ca 3 Fe 2 Si 3 O 12 phase, which are 3.5% and 3.0%, respectively. Through in-situ heating experiments, XRD-Rietveld and SEM-EDS, the macro morphology and phase composition of the hardened samples were compared and analyzed. Finally, a multiple regression model is used to predict the liquid content of hematite pellets, which is effective in predicting the phase component.
In recent years, lithium iron phosphate (LFP) batteries have been widely used in the electric vehicle industry. The recycling of spent LFP will be propitious to conserving resources and alleviating the environmental risks it poses. In this study, a selective extraction method for lithium from spent LFP was proposed using nitric acid . Lithium leached into the liquid phase, while P and Fe remained in the leaching residue. Under the conditions of 120°C, HNO 3 /Li molar ratio of 2, and time of 2 h, the leaching efficiency of lithium reached 99.5 %, with a selectivity reaching 82.1 %. Initially, LFP was decomposed to liberate Li, Fe, and P in the liquid phase. Subsequently, ferrous ions were oxidized to trivalent, high-valent iron ions re-precipitated as FePO 4 ·2 H 2 O. Thermodynamic calculations indicate that the temperature and pH value of the extraction system have significant influence on both the oxidation and reprecipitation steps. An imbalance of Fe/P ratio (<1) in the raw material hinders the selectivity of lithium extraction , and supplementing this portion of Fe can enhance the selectivity to over 90 %. Additionally, LiCO 3 and anhydrous FePO 4 were effectively regenerated from the leachate and residue. This study provides a novel approach for the recycling of spent LFP and probably contributes to the sustainability of the lithium ion battery industry.
危险品化学品经营许可证（带存储）