摘要
针对磷铁渣资源化过程中存在的铁磷综合利用率低、铝杂质深度脱除难等问题,基于Na_(3)PO_(4)和NaAlO_(2)的溶解特性差异,开展钠碱浸出—冷却结晶深度脱铝后再生电池级磷酸铁的研究。研究结果表明:对铁磷铝分离体系进行热力学分析,在浸出液pH>12.47的条件下,Fe(OH)3可选择性沉淀进入固相,而可溶性Na_(3)PO_(4)进入液相;控制冷却结晶,液相中的Na_(3)PO_(4)优先结晶析出,而NaAlO_(2)保持溶解状态。在优化参数(NaOH浓度为3.0 mol/L、液固比为11꞉1 mL/g、温度为60℃、浸出时间为4 h)下浸出,浸出参数符合铁磷铝分离热力学条件,磷回收率可达89.42%,Al质量分数低至0.0019%,实现铁-磷-铝三元素的高效分离。以回收的磷源与酸浸铁源为原料,优化液相沉淀工艺(Fe^(3+)浓度为0.7 mol/L、反应温度为95℃、初始pH为0.6、原料P与Fe物质的量比n(P)/n(Fe)为0.8),制备出高纯度磷酸铁产品。产物中Al质量分数仅为0.016%,Fe与P物质的量比n(Fe)/n(P)为0.996,满足HG/T 4701—2021《电池用磷酸铁》标准要求。
To address the challenges of low comprehensive iron/phosphorus utilization and difficult deep aluminum removal in the recycling of lithium-extraction iron-phosphorus slag,a sodium alkali leaching-cooling crystallization process was proposed based on the solubility differences between Na_(3)PO_(4)and NaAlO_(2)to achieve deep aluminum removal and regenerate battery-grade iron(III)phosphate(FePO_(4)).The thermodynamic analysis of the Fe-P-Al separation system was carried out.The results demonstrate that under the condition of pH>12.47,Fe(OH)3 can selectively precipitate into the solid phase,while soluble Na_(3)PO_(4)enters the liquid phase.By controlling the cooling crystallization,Na_(3)PO_(4)in the liquid phase is preferentially crystallized,while NaAlO_(2)remains dissolved.With the optimized parameters(NaOH concentration 3.0 mol/L,liquid-solid ratio 11:1 mL/g,60℃,4 h),the leaching conforms to the thermodynamic conditions of Fe-P-Al separation.The phosphorus recovery rate can reach 89.42%,and the mass fraction of Al is as low as 0.0019%,which realizes the efficient separation of Fe-P-Al tri-element separation.Using the recovered phosphorus source and acid-leached iron source,high-purity FePO_(4)is synthesized via an optimized liquid-phase precipitation process(0.7 mol/L Fe^(3+),95℃,initial pH 0.6,P and Fe molar ratio 0.8).The product exhibits an Al content of only 0.016%and molar ratio of Fe and P of 0.996,fully complying with the battery-grade FePO_(4)standards(HG/T 4701—2021).
作者
杨卫春
姜梅
赵思颖
禹林
姜智
YANG Weichun;JIANG Mei;ZHAO Siying;YU Lin;JIANG Zhi(School of Metallurgy and Environment,Central South University,Changsha 410083,China;Zhongye Changtian International Engineering Co.Ltd.,Changsha 410205,China)
出处
《中南大学学报(自然科学版)》
北大核心
2025年第8期3502-3512,共11页
Journal of Central South University:Science and Technology
基金
国家自然科学基金资助项目(52274170)
中冶长天国际工程有限责任公司科技项目(2024JCYJ10)。
关键词
磷铁渣
碱浸
磷酸铁
脱铝
lithium-extraction iron-phosphorus slag
alkali leaching
iron(III)phosphate(FePO_(4))
aluminum removal
