废旧磷酸铁锂粉料综合回收中试研究

doi:10.11949/0438-1157.20240004

摘要/Abstract

摘要：

为研究废旧磷酸铁锂粉料（LFP/C）经高温煅烧-中和沉淀除杂后实现电池级磷酸铁和碳酸锂综合回收的效能，本研究以氟/铝含量较高的废旧LFP/C为对象，构建了年处理规模为500 t的中试平台，从工艺稳定性、产品性能表征、初步经济评估及二次废渣再利用等角度进行研究。结果显示，通过此法可实现高于85%铝去除和94%钛去除，除铝液中铁铝质量比由200增加至1077，为废旧LFP/C综合回收奠定基础。所制备的FePO₄及Li₂CO₃符合电池级标准，再生的LFP/C正极材料在0.1C条件下首次充放电库伦效率可达95.2%，1C条件下经过250圈循环后容量保持率达97.1%，展现出较好的电化学性能。此外，经济评估进一步凸显了该工艺在经济和环境效益方面的优越性。

关键词: 废旧磷酸铁锂, 前驱体, 电化学性能, 中试规模, 经济分析

Abstract:

This work aims to evaluate the efficiency of comprehensive recovery of battery-grade iron phosphate (FePO₄) and lithium carbonate (Li₂CO₃) from spent lithium iron phosphate cathode powder (LFP/C) with high fluorine/aluminum content following high-temperature calcination-neutralization precipitation. A pilot-scale platform with an annual processing capacity of 500 tons was established. The investigation includes process stability, product performance characterization, preliminary economic assessment, and the reutilization of secondary slag. The results demonstrate that over 85% aluminum removal and 94% titanium removal can be achieved through this process, with the Fe/Al mass ratio in the purified liquid increasing from 200 to 1077, laying a foundation for comprehensive recycling of spent LFP/C. The prepared FePO₄ and Li₂CO₃ met the standards for battery-grade materials. The regenerated LFP/C cathode material exhibits a first-cycle coulombic efficiency of 95.2% at 0.1 C, and a capacity retention of 97.1% after 250 cycles at 1 C, indicating its favorable electrochemical performance. Additionally, economic assessment underscores the superiority of this process in terms of economic and environmental benefits.

Key words: spent LiFePO₄/C, precursors, electrochemical performance, pilot-scale, economic analysis

中图分类号:

X703

江洋, 彭长宏, 陈伟, 周豪, 马忠彬, 李洪博, 邱在容, 张国鹏, 周康根. 废旧磷酸铁锂粉料综合回收中试研究[J]. 化工学报, DOI: 10.11949/0438-1157.20240004.

Yang JIANG, Changhong PENG, Wei CHEN, Hao ZHOU, Zhongbin MA, Hongbo LI, Zairong QIU, Guopeng ZHANG, Kanggen ZHOU. Pilot-scale comprehensive recovery of spent LiFePO₄/C materials[J]. CIESC Journal, DOI: 10.11949/0438-1157.20240004.

图/表 12

表1 该工艺各步骤涉及的反应方程式

Table 1 The reaction equations involved in each step of the process

反应步骤	化学反应
煅烧脱氟	$L i P F 6 + H 2 O ⟶ 2 H F ↑ + L i F + P O F 3$ $L i F + H 3 P O 4 ⟶ H F ↑$
煅烧脱氟	$P O F 3 + 3 H 2 O ⟶ 3 H F ↑ + H 3 P O 4$
浸出过程	$2 L i F e P O 4 + 2 H 2 S O 4 ⟶ L i 2 S O 4 + F e S O 4 + F e (H 2 P O 4) 2$
浸出过程	$2 A l + 3 H 2 S O 4 ⟶ A l 2 (S O 4) 3 + 3 H 2 ↑$ $T i O 2 + 2 H 2 S O 4 ⟶ T i (S O 4) 2 + 2 H 2 O$ $2 A l P O 4 · x H 2 O + 3 H 2 S O 4 ⟶ A l 2 (S O 4) 3 + 2 H 3 P O 4 + x H 2 O$
中和除杂	$A l 2 (S O 4) 3 + 2 H 3 P O 4 + 3 F e + x H 2 O ⟶ 2 A l P O 4 · x H 2 O ↓ + 3 F e S O 4 + 3 H 2 ↑$ $T i (S O 4) 2 + 3 H 2 O ⟶ H 2 T i O 3 ↓ + 2 H 2 S O 4$
沉磷酸铁	$2 F e S O 4 + H 2 O 2 + H 2 S O 4 ⟶ F e 2 (S O 4) 3 + 2 H 2 O$ $F e 2 (S O 4) 3 + 2 N a H 2 P O 4 + 4 H 2 O ⟶ 2 F e P O 4 · 2 H 2 O ↓ + N a 2 S O 4 + 2 H 2 S O 4$ $A l 2 (S O 4) 3 + 2 H 3 P O 4 + 2 x H 2 O ⟶ 2 A l P O 4 · x H 2 O ↓ + 3 H 2 S O 4$
深度除杂	$F e 2 (S O 4) 3 + 6 N a O H ⟶ 2 F e (O H) 3 ↓ + 3 N a 2 S O 4$ $M e S O 4 + 2 N a O H ⟶ M e (O H) 2 ↓ + 2 N a 2 S O 4$ （Me为二价金属离子）
回收锂	$L i 2 S O 4 + N a 2 C O 3 ⟶ L i 2 C O 3 ↓ + 3 N a 2 S O 4$ $L i 2 C O 3 + C O 2 + H 2 O ⟶ 2 L i H C O 3$ $2 L i H C O 3 ⟶ L i 2 C O 3 ↓ + C O 2 ↑ + H 2 O$ $3 L i 2 S O 4 + 2 N a H 2 P O 4 + 4 N a O H ⟶ L i 3 P O 4 ↓ + 3 N a 2 S O 4 + 4 H 2 O$

表1 该工艺各步骤涉及的反应方程式

Table 1 The reaction equations involved in each step of the process

反应步骤	化学反应
煅烧脱氟	$L i P F 6 + H 2 O ⟶ 2 H F ↑ + L i F + P O F 3$ $L i F + H 3 P O 4 ⟶ H F ↑$
煅烧脱氟	$P O F 3 + 3 H 2 O ⟶ 3 H F ↑ + H 3 P O 4$
浸出过程	$2 L i F e P O 4 + 2 H 2 S O 4 ⟶ L i 2 S O 4 + F e S O 4 + F e (H 2 P O 4) 2$
浸出过程	$2 A l + 3 H 2 S O 4 ⟶ A l 2 (S O 4) 3 + 3 H 2 ↑$ $T i O 2 + 2 H 2 S O 4 ⟶ T i (S O 4) 2 + 2 H 2 O$ $2 A l P O 4 · x H 2 O + 3 H 2 S O 4 ⟶ A l 2 (S O 4) 3 + 2 H 3 P O 4 + x H 2 O$
中和除杂	$A l 2 (S O 4) 3 + 2 H 3 P O 4 + 3 F e + x H 2 O ⟶ 2 A l P O 4 · x H 2 O ↓ + 3 F e S O 4 + 3 H 2 ↑$ $T i (S O 4) 2 + 3 H 2 O ⟶ H 2 T i O 3 ↓ + 2 H 2 S O 4$
沉磷酸铁	$2 F e S O 4 + H 2 O 2 + H 2 S O 4 ⟶ F e 2 (S O 4) 3 + 2 H 2 O$ $F e 2 (S O 4) 3 + 2 N a H 2 P O 4 + 4 H 2 O ⟶ 2 F e P O 4 · 2 H 2 O ↓ + N a 2 S O 4 + 2 H 2 S O 4$ $A l 2 (S O 4) 3 + 2 H 3 P O 4 + 2 x H 2 O ⟶ 2 A l P O 4 · x H 2 O ↓ + 3 H 2 S O 4$
深度除杂	$F e 2 (S O 4) 3 + 6 N a O H ⟶ 2 F e (O H) 3 ↓ + 3 N a 2 S O 4$ $M e S O 4 + 2 N a O H ⟶ M e (O H) 2 ↓ + 2 N a 2 S O 4$ （Me为二价金属离子）
回收锂	$L i 2 S O 4 + N a 2 C O 3 ⟶ L i 2 C O 3 ↓ + 3 N a 2 S O 4$ $L i 2 C O 3 + C O 2 + H 2 O ⟶ 2 L i H C O 3$ $2 L i H C O 3 ⟶ L i 2 C O 3 ↓ + C O 2 ↑ + H 2 O$ $3 L i 2 S O 4 + 2 N a H 2 P O 4 + 4 N a O H ⟶ L i 3 P O 4 ↓ + 3 N a 2 S O 4 + 4 H 2 O$

图1 中试工艺流程图和实物图

Fig. 1 Pilot process flow diagram and physical image

表2 废旧LFP/C煅烧前后有价元素浸出率的变化

Table 2 Variations in leaching rates of valuable elements in spent LFP/C before and after calcination

浸出率 /%	Fe	P	Li	Al	F	Ti	Mn	Ni	Co
煅烧前	97.7	96.5	99.8	83.1	75.2	67.3	95.4	95.8	75.9
煅烧后	90.4	87.8	97.6	42.3	0.03	57.5	94.8	93.7	63.3

表3 除铝后溶液中离子浓度变化

Table 3 Alterations in ionic concentrations in solution upon aluminum removal

元素	Fe g/L	P g/L	Li g/L	Al /mg/L	Ti /mg/L	Mn /mg/L	Ni /mg/L	Co /mg/L
沉降率 /%	10.67	13.22	0.03	85.63	94.70	—	—	—
浸出液中浓度	77	41.8	10.7	380	315	82	55	20
净化液中浓度	82.9	38.4	12.4	77	22	80	12	14

表4 电池用磷酸铁产品组成成分

Table 4 Chemical analysis of battery-grade iron phosphate products

元素	Fe	P	Li	Al	Ti	Mn	Ni	Cu	Co	Ca	F
含量 /%	36.02	20.31	0.004	0.011	0.002	0.003	0.002	0	0	0	0

图2 磷酸铁产品物化性能表征

Fig. 2 Characterization of iron phosphate products

图3 碳酸锂产品的物相和微观形貌分析

Fig. 3 Phase composition and microscopic morphology of Li2CO3 products

图4 再生LFP/C电化学性能研究

Fig. 4 Electrochemical performance of regenerated LFP/C materials

图5 二浸渣的物相分析

Fig. 5 Phase composition of secondary leaching residue

表5 陶瓷用磷酸铁成分分析

Table 5 Chemical analysis of FePO4 for ceramic applications

元素	Fe	P	Li	Al	Ti	Mn	Ni	Cu	Co	Ca	F
含量 /%	36.18	20.48	0.005	0.071	0.026	0.003	0.001	0	0	0	0

表6 实验过程中各元素的平衡计算

Table 6 Balancing calculations of each element from the expending test

投加/产出 /kg	Fe	P	Li
平衡率 /%	99.35	98.64	99.94
废旧LFP/C粉料	-638.6	-390.6	-87.8
浓磷酸	0	-51.5	0
工业铁粉	-90.3	0	0
磷酸二氢钠	0	-29.1	0
副产亚铁	-55.5	0	0
磷酸铁	+751.9	+416.2	+0.06
碳酸锂	0	0	+71.8
磷酸锂	0	+15.5	+10.4
难溶渣	+16.9	+13.7	+0.96
二浸渣	+4.8	+9.6	+0.43
提锂液	0	0	+0.3
洗涤水（系统循环）	+5.7	+9.8	+3.8

表7 回收2.0吨废旧LFP/C的投入与产出量

Table 7 The input and output for processing 2.0 t of spent LFP/C

序号	消耗/产生	参考价格	消耗/产出量	费用/CNY
17	总利润			+14013
1	废旧LFP/C粉料	￥13000/t	-2.0 t	-26000
2	硫酸	￥200/t	-2.0 t	-400
3	磷酸	￥6800/t	-170 kg	-1156
4	工业铁粉	￥2500/t	-110 kg	-275
5	自来水	￥4.1/m³	-10 m³	-41
6	磷酸二氢钠	￥5800/t	-150 kg	-870
7	双氧水	￥1250/m³	-1.2 m³	-1500
8	氢氧化钠	￥3500/t	-3.2 t	-11200
9	碳酸钠	￥2950/t	-750 kg	-2212
10	副产亚铁	￥400/t	-270 kg	-108
11	一般固废处理	￥300/t	1.0 t	-300
12	危废处理	￥3000/t	300 kg	-900
13	电池用磷酸铁	￥11000/t	1.20 t	+13200
14	陶瓷用磷酸铁	￥6000/t	840 kg	+5040
15	电池级碳酸锂	￥93000/t	385 kg	+35805
16	磷酸锂	￥85000/t	58 kg	+4930

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