硅酸盐学报

退役LiFePO₄电池拆解得到的正极粉一般通过酸浸进行回收，但酸浸后还含有大量杂质，需再次进行除杂才能回收利用。本工作采用废LiFePO₄含锂浸出液，通过还原除铜、中和除铁铝磷、碱化除镍钴锰、树脂除钙和吸附除氟，进行杂质的去除，得到可进行沉锂的净化液。结果表明：铁粉加入量为理论量的1.1倍，铜回收率达到99.95%。在最优实验条件下，用Ca(OH)₂可将Fe、Al、P大部分除去，去除率分别为86.11%、70.75%和99.27%。同时，贵重金属Ni、Co、Mn损失低于5%。采用纯碱除杂，Ni、Co、Mn、Cu和Al等金属几乎沉淀完全，沉淀率均达99.5%以上，可以除到5 mg/L以下。50℃下HP4040树脂对Ca的单级吸附达91.6%以上。以廉价的β锂辉石为原料，制备的MgO修饰β锂辉石可进行除氟，对F的单次吸附率可达85.8%以上，为开发低成本深度除氟材料提供一条路径。

Introduction The complexity of lithium iron phosphate waste sources dictates the intricate composition of the solution after acid leaching. Particularly during the pretreatment process, lithium iron phosphate waste can become mixed with anode materials and may contain trace amounts of nickel, cobalt, and manganese. Therefore, in addition to the characteristic impurities of lithium iron phosphate, such as iron, aluminum, and phosphate, the acid leach solution obtained from lithium iron phosphate waste through high-pressure oxidation leaching is typically accompanied by small amounts of copper, nickel, cobalt, manganese, fluorine, and other impurity elements. On one hand, regarding product purity, if these impurity elements are not adequately removed, they may lead to the deterioration of lithium carbonate quality, adversely affecting subsequent processing. On the other hand, considering recycling value, metals like copper, nickel, and cobalt have significant market value, necessitating their recovery to improve the economic viability of the entire process. Methods Remove Cu, Fe, Al, P, Ni, Co, Mn and other impurities by chemical method. Removal of calcium impurities by HP4040 resin. The adsorption process of Ca²⁺ was correlated using kinetic equations, confirming that the adsorption process of HP4040 resin for calcium removal aligns more closely with a pseudo-second-order kinetic model. This indicates that the adsorption reaction between calcium ions and the resin is predominantly governed by chemical adsorption. Thermodynamic analysis revealed that the adsorption process of calcium ions on the resin conforms to the Langmuir isotherm model. Removal of fluorine impurities by modification of Mg O-modified β-spodumene, both pseudo-first-order and pseudo-second-order kinetic equations were employed to describe the adsorption of fluoride ions onto the adsorbent. The fitting results suggest that the fluoride adsorption process largely adheres to the pseudo-second-order kinetic model. Thermodynamic analysis further indicated that the adsorption of fluoride by the defluorination agent aligns better with the Langmuir model, suggesting a preference for monolayer adsorption. Results and discussion The main conclusions of this study are summarized as follows. This research systematically investigates the purification and decontamination processes of waste LiFePO₄ lithium-containing leach solutions, focusing on the reduction and removal of copper, neutralization of iron, aluminum, and phosphorus, alkalization for nickel, cobalt, and manganese removal,resin-based calcium removal, and adsorption for fluoride removal. The distribution of impurity ions in the acid leach solution, including Fe, Al, Cu, Ni, Co, Mn, Ca, and F, has been analyzed throughout the decontamination process, and the entire flow of acid leach solution decontamination has been experimentally validated. The findings are as follows: To effectively reduce and remove copper, the optimal addition of iron powder is 1.1 times the theoretical amount, achieving a recovery rate of 99.95% and a copper sponge purity of 95.02%. For neutralization to remove iron, aluminum, and phosphorus, the optimal reaction conditions are a temperature of 30 ℃, an endpoint p H value of 4, and a reaction time of 30 min. Under these conditions, the impurity elements Fe, Al, and P are predominantly removed, while the loss of valuable metals like Ni, Co, and Mn is minimal. In the alkalization process for removing Ni, Co, and Mn, precipitation occurs at pH 12, with precipitation rates exceeding 99.5% for all target metals. The resin-based calcium removal process studies and compares the advantages of three commercially available calcium removal resins, ultimately selecting HP4040 resin, which demonstrates a maximum adsorption capacity of 35.28 mg/g for calcium, achieving over 91.6% single-stage calcium adsorption. Meanwhile, the synthesized Mg O-modified β-spodumene adsorbent material achieves a single-stage adsorption rate of over 85.8% for fluoride, providing a pathway for developing low-cost deep fluoride removal materials. Conclusions This study systematically investigates the purification and decontamination process for waste LiFePO₄ lithium leach solutions. After the reduction to remove copper, neutralization to eliminate iron, aluminum, and phosphorus, alkalization for nickel, cobalt, manganese removal, resin-based calcium removal, and adsorption for fluoride removal, the purification of the liquid obtained allows for lithium carbonate recovery.