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| Preparation of iron red using reductive acid leaching solution from iron residue of NdFeB waste by crystal seed synthesis method |
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Received:March 07, 2023
Revised:March 15, 2023
Accepted:March 16, 2023
Published Online:June 25, 2023
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| DOI： |
| KeyWord:ammonia method; γ-FeOOH; seed crystal; acid leaching solution; iron red |
| Author | Institution |
| Zhang liping |
Nanchang University |
| Du haojie |
Ganjiang Innovation Academy, Chinese Academy of Sciences |
| Xiao wanhai |
Ganjiang Innovation Academy, Chinese Academy of Sciences |
| Qi tao |
Ganjiang Innovation Academy, Chinese Academy of Sciences |
| Wang Zhi |
Institute of Process Engineering, Chinese Academy of Sciences |
| Wang Dong |
Institute of Process Engineering, Chinese Academy of Sciences |
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| Abstract: |
| The iron residue was produced by the extraction of rare earth by hydrochloric acid from NdFeB waste. The residue contains a small amount of rare earth and cobalt valuable metals and a large amount of iron oxide, which has high recycling value. In the previous study of our group, the method of reducing acid leaching to extract rare earth and cobalt from iron tailings was proposed. It can effectively solve the problem of high residual rare earth in the residue. However, the abundant ferrous sulfate in the reduced acid leaching solution has not been effectively reused. Solution of waste with high iron content is generally used to prepare pigment grade iron red. At present, the ammonia process is an environmentally friendly and promising process. However, oxidation preparation γ-FeOOH has a narrow window, which is prone to problems such as mixed crystal and uneven morphology, and the process conditions are strictly controlled. In view of the complex influencing factors of the process and the difficulty in regulating the directional induced crystallization, it is necessary to further analyze the oxidation synthesis process. In this paper, the precursor γ-FeOOH active seeds were prepared by air oxidation method using reductive acid leaching solution from iron tailings of NdFeB waste as raw material and NH3·H2O as precipitant. Firstly, the impurity ion Al3+, which has a great influence on the morphology of the seed, was removed by adjusting the pH of the ammonia water to improve the activity of the seed. Secondly, the formation of heterogeneous Fe3O4 and α-FeOOH was inhibited by the thermodynamically stable region, and the active seeds with needle-like structure and uniform dispersion were prepared. Finally, the process parameters of oxidation synthesis of iron oxide red were clarified and the synthesis mechanism was discussed. The process realizes the regeneration of waste and produces value-added products. |
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