基于磷酸铁锂提锂渣的电池级磷酸铁制备工艺研究  

Study on the technology for preparation of battery grade iron phosphate based on lithium iron phosphate slag

作　　者：姚家涛 张勇[1] 韩培林 桑子容 汪思琪 Yao Jiatao;Zhang Yong;Han Peilin;Sang Zirong;Wang Siqi(School of Materials Science and Engineering,Wuhan Institute of Technology,Wuhan Hubei 430205,China)

机构地区：[1]武汉工程大学材料科学与工程学院,湖北武汉430205

出　　处：《化工矿物与加工》2023年第9期1-5,共5页Industrial Minerals & Processing

基　　金：青海省科技计划(2020-GX-103);海西州科技计划(2019-101);武汉工程大学研究生教育创新基金(CX2022268)。

摘　　要：目前在磷酸铁锂电池正极材料回收时往往仅回收其中经济价值高的锂元素,而产生的提锂渣中大量磷酸铁因杂质中的铝元素脱除困难导致无法回收利用,造成了巨大的资源浪费。为此,提出了一种使用硝酸浸提磷酸铁的方法。首先在浸出液中加入甲醇电解还原浸出液中的铁离子,再向还原液中加入氢氟酸作为沉淀剂脱除酸浸液中的铝离子,脱铝后的酸浸液用过氧化氢将亚铁离子氧化为铁离子,再加入甲醛并加热沉淀出电池级磷酸铁。研究结果表明:在浸取温度70℃、硝酸浓度5 mol/L、酸浸40 min的条件下,Fe的浸出率为92.7%;经电解还原亚铁后脱铝制备出了Al质量分数仅为72 mg/kg的磷酸铁,满足HG/T 4701-2021《电池用磷酸铁》的Ⅱ型标准。该方法为磷酸铁锂提锂渣的回收利用提供了一条新思路。At present,only the lithium element of high value is usually able to be recycled when we try to reclaim the cathode material of lithium iron phosphate battery,but a large amount of iron phosphate remained in the lithium extraction slag because of the difficulty in removing the aluminum element from the impurities,resulting in a huge waste of resources.Therefore,an approach to extracting iron phosphate with nitric acid was proposed.Firstly,methanol was added to the leaching solution for electrolysis and reduction of the iron ions contained,and then addition of hydrofluoric acid as a precipitant to the solution to remove the aluminum from the acid leaching solution after which was subject to oxidization with hydrogen peroxide to transform ferrous ions into iron ions,finally heating the solution with addition of formaldehyde facilitated the precipitation of battery-grade iron phosphate.The results show that the leaching rate of Fe was up to 92.7%as the acid leaching was operated at a temperature of 70℃with nitric acid dosage of 5 mol/L and lasted for 40 min.The iron phosphate containing only 72 mg/kg Al was obtained after removing aluminum by electrolysis-reduction of ferrous iron,of which the quality meet the specifications for iron phosphate of Grade B for battery purpose as stated in standard HG/T 4701-2021.This approach provides a new solution to the recovery and utilization of lithium iron phosphate slag.

关 键 词：磷酸铁 正极材料 酸浸 脱铝 电解 硝酸 

分 类 号：X705[环境科学与工程—环境工程]