2023 Fiscal Year Final Research Report
Thermochemical studies of phosphates for recycling battery material and removing phosphorus from molten iron
| Project/Area Number |
21K04737
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Multi-year Fund |
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| Section | 一般 |
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| Review Section |
Basic Section 26060:Metals production and resources production-related
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| Research Institution | Kyoto University |
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Principal Investigator |
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| Project Period (FY) |
2021-04-01 – 2024-03-31
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| Keywords | リン酸 / 電池材料 / 再資源化 / 鉄鋼プロセス |
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| Outline of Final Research Achievements |
Although phosphorus is one of impurities in liquid steel, phosphorus is expected to be recovered as a raw material for fertilizer and battery. Both of dephosphorization slag in steelmaking process and LiFePO4, which is one of the cathode materials in Lithium-ion batteries, are considered to be basic oxide-P2O5-FeO systems. Based on this consideration, this study has been aimed at determining chemical properties of phosphate in basic oxide-P2O5-FeO systems. In this study, the P2O5 activities in these systems could be measured in the wide temperature range. When FeO in LiFePO4 was reduced and removed as metallic iron, 86% of Li could be recovered. In dephosphorization slags, the P2O5 activity decreased drastically when Ca2+ in Ca2SiO4-Ca3P2O5 solid solutions was replaced with Fe2+. In order to realize carbon neutrality, I would like to continue to investigate the chemical properties of phosphate using the present results.
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| Free Research Field |
化学熱力学
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| Academic Significance and Societal Importance of the Research Achievements |
鉄鋼精錬スラグは塩基性酸化物-酸性酸化物-FeO系であるが、リチウムイオン電池正極材料LiFePO4も塩基性酸化物Li2O-酸性酸化物P2O5-FeO系と言える。LiFePO4リサイクルから鉄鋼精錬までの幅広い温度域におけるリン酸塩の活量測定法を確立でき、リン酸塩に関する測定値や文献値の精度を考察した。本研究課題ではLiFePO4からのLi回収反応と溶鉄からの脱リン反応に関わるデータの測定・解析を行った。今後、自動車や再生可能エネルギー向けの蓄電池の需要が増加し、水素還元鉄では不純物除去での負荷が増大すると予想される。カーボンニュートラル社会実現に向け、本研究成果を活用しさらに発展させたい。
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