易葵, 陈伟(通讯作者). 锂钠冰晶石的沉淀溶解平衡研究[J]. 工程科学学报. DOI: 10.13374/j.issn2095-9389.2023.12.01.002
引用本文: 易葵, 陈伟(通讯作者). 锂钠冰晶石的沉淀溶解平衡研究[J]. 工程科学学报. DOI: 10.13374/j.issn2095-9389.2023.12.01.002
Study on Precipitation Dissolution Equilibrium of Lithium Sodium Cryolite[J]. Chinese Journal of Engineering. DOI: 10.13374/j.issn2095-9389.2023.12.01.002
Citation: Study on Precipitation Dissolution Equilibrium of Lithium Sodium Cryolite[J]. Chinese Journal of Engineering. DOI: 10.13374/j.issn2095-9389.2023.12.01.002

锂钠冰晶石的沉淀溶解平衡研究

Study on Precipitation Dissolution Equilibrium of Lithium Sodium Cryolite

  • 摘要: 本文以硫酸铝、硫酸锂、硫酸钠和氟化铵为原料,通过调控氟铝配位合成锂钠冰晶石(Na3Li3Al2F12),研究其沉淀溶解平衡行为,为废旧 LiFePO4 粉料酸浸液氟化配位除Al 提供依据。系统考察了配位沉淀过程中F-/Al3+ 摩尔比、Na+/Al3+ 摩尔比、Li+/Al3+ 摩尔比、反应初始 pH、反应温度以及反应时间的影响。得出优化的沉淀条件:F-/Al3+ 摩尔比为 7、Na+/Al3+ 摩尔比为1.5、Li+/Al3+摩尔比为2、反应温度70 ℃、反应pH为4.5以及反应时间3 h。在最佳工艺条件下,氟化剂配位沉Al 后,滤液中各离子浓度趋于稳定,其中Al3+ 浓度为75.43 mg/L。在温度30℃,pH小于3时,酸度越大,Na3Li3Al2F12 的溶解度越大,pH大于3时,pH值对Na3Li3Al2F12 溶解度影响不大。为验证其具有指导意义,在实际应用中,废旧 LiFePO4 正极材料酸浸液 NaF 配位沉 Al 后,Al3+ 沉淀率达 99.4%,实现深度除 Al。

     

    Abstract: This article uses aluminum sulfate, lithium sulfate, sodium sulfate, and ammonium fluoride as raw materials to synthesize lithium sodium cryolite (Na3Li3Al2F12) by regulating the coordination of fluorine and aluminum. The precipitation dissolution equilibrium behavior of Na3Li3Al2F12 is studied, providing a basis for the fluorination coordination and removal of Al from waste LiFePO4 powder acid leaching solution. The system investigated the effects of F-/Al3+ molar ratio, Na+/Al3+ molar ratio, Li+/Al3+ molar ratio, initial reaction pH, reaction temperature, and reaction time on the coordination precipitation process. Obtain optimized precipitation conditions: F-/Al3+ molar ratio of 7, Na+/Al3+ molar ratio of 1.5, Li+/Al3+ molar ratio of 2, reaction temperature of 70 ℃, reaction pH of 4.5, and reaction time of 3 hours. Under the optimal process conditions, after the fluorinating agent coordinates and precipitates Al, the concentrations of various ions in the filtrate tend to stabilize, with an Al3+ concentration of 75.43 mg/L. When the temperature is 30 ℃ and the pH is less than 3, the higher the acidity, the greater the solubility of Na3Li3Al2F12. When the pH is greater than 3, the pH value has little effect on the solubility of Na3Li3Al2F12. To verify its guiding significance, in practical applications, the precipitation rate of Al3+ reached 99.4% after NaF coordination precipitation of waste LiFePO4 cathode material acid leaching solution, achieving deep removal of Al.

     

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