有色金属(选矿部分)

针对传统锂云母提锂工艺(高温焙烧高能耗、强酸浸出高污染)的核心痛点，本文以江西宜春锂云母精矿(Li_2O品位3.70%)为研究对象，系统探究草酸浓度、浸出时间、反应温度及液固比等关键参数对锂浸出行为的影响规律，构建高效、绿色、可循环的草酸浸出提锂工艺。通过单因素变量试验优化得出最佳工艺条件：草酸浓度4 mol/L、反应时间8 h、反应温度110℃、液固比7.5 mL/g，锂浸出率可以达到93.63%。为降低试剂消耗与环境负荷，采用冷却结晶法对浸出后液进行处理，单次草酸回收率为71.21%，经化学滴定法验证回收草酸纯度为96.92%，回用于新一轮浸出试验仍能保持93.12%的高锂浸出率，证实草酸具备优异的循环复用性能。借助XRD与XRF技术对浸出残渣进行系统分析，揭示了草酸浸出的核心机理，即通过“酸解—络合”协同作用破坏锂云母层状硅酸盐晶体结构，选择性溶出锂、铝、钾及稀有碱金属铷、铯等有价元素，而石英、钠长石等伴生矿物结构保持稳定，有效降低后续分离难度。该工艺无需高温焙烧预处理，避免了有害气体排放与强酸腐蚀问题，同时实现草酸闭路循环，显著降低试剂消耗与废液处理压力，为锂云母资源的高效资源化利用提供了理论支撑与技术参考。

Addressing the core challenges of traditional lithium extraction from lepidolite— namely,the high energy consumption of high-temperature roasting and the significant pollution caused by strong acid leaching— this study investigated an efficient,green,and recyclable oxalic acid leaching process using lepidolite concentrate from Yichun,Jiangxi Province,China(with a Li_2O grade of 3. 70%). The effects of key parameters— including oxalic acid concentration,leaching time,reaction temperature,and liquid-to-solid ratio— on the lithium leaching behavior were systematically examined. Through single-factor optimization experiments,the optimal process conditions were determined:an oxalic acid concentration of 4 mol/L,a reaction time of 8 hours,a temperature of 110 ℃,and a liquid-to-solid ratio of 7. 5 mL/g. Under these conditions,a lithium leaching efficiency of 93. 63% was achieved. To minimize reagent consumption and environmental impact,the leach liquor was treated via cooling crystallization,achieving a single-pass oxalic acid recovery rate of 71. 21%. Chemical titration confirmed the purity of the recovered oxalic acid at 96. 92%. When reused in subsequent leaching cycles,it maintained a high lithium extraction rate of 93. 12%,demonstrating its excellent recyclability. Systematic analysis of the leaching residues using XRD and XRF techniques elucidated the core mechanism of oxalic acid leaching:a synergistic “acid dissolution-complexation” action that disrupts the layered silicate crystal structure of lepidolite. This selectively dissolves lithium, aluminum,potassium,and valuable rare alkali metals such as rubidium and cesium,while stabilizing the structures of associated minerals like quartz and albite,thereby reducing subsequent separation difficulties. This process eliminates the need for high-temperature roasting pretreatment,avoiding harmful gas emissions and strong acid corrosion issues. Simultaneously,it achieves closed-loop oxalic acid recycling,significantly reducing reagent consumption and waste liquid treatment pressure. This study provides a theoretical foundation and technical reference for the efficient resource utilization of lepidolite.