A discussion on the leaching process of the ion-adsorption type rare earth ore with the electrical double layer model

Xiao, Yanfei; Gao, Guohua; Li, Huang; Feng, Zongyu; Fuguo, Lai; Long, Zhiqi

doi:10.1016/j.mineng.2018.02.015

Cited by 42 publications

(10 citation statements)

References 22 publications

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“…According to Arrhenius equation, the activation energy of the ion-exchange reaction of Al 3+ was 10.48 kJ/mol, which is presented in Figure 9B. Due to the higher valence state of hydrated Al 3+ , the charge density of hydrated Al 3+ is larger than that of calcium, so clay minerals have a greater adsorption ability on Al 3+ [5,31]. Therefore, the aluminum leaching process has a larger activation energy and a smaller leaching rate.…”

Section: Leaching Kinetics Of Aluminummentioning

confidence: 99%

“…The development of ICREO can solve the problem that bastnaesite and Baotou mixed rare earth ore can only produce light rare earth and lack medium and heavy rare earth elements [2]. According to the characteristics of the IEP-RE in ICREO being easily desorbed when encountering Na + , NH 4 + , and Mg 2+ and so on [5][6][7], a series of leaching agents and leaching technologies for ICREO have been put forward by scientists in China. Currently, rare earth is leached from ICREO by an in situ leaching process with ammonium sulfate leaching agent [2].…”

Section: Introductionmentioning

confidence: 99%

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Leaching Behaviors of Calcium and Aluminum from an Ionic Type Rare Earth Ore Using MgSO4 as Leaching Agent

Qiu

Rao

et al. 2021

Minerals

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During the leaching process of ionic rare earth ore (ICREO), ion-exchangeable phase calcium (IEP-Ca) and ion-exchangeable phase aluminum (IEP-Al) are leached along with rare earth, which causes many problems in the enrichment process, such as increasing the precipitant agent consumption and rare earth loss, etc. The agitation leaching kinetics and the column leaching mass transfer process of IEP-Ca and IEP-Al were studied to understand the leaching behavior of impurity in ICREO, which provides guides for the adjustment of the leaching process and to limit the co-leaching of impurities. IEP-Ca and IEP-Al were leached by ion exchange, with the leaching agent cations and the leaching kinetics described by an internal diffusion-controlled shrinking core model with an apparent activation energy of 8.97 kJ/mol and 10.48 kJ/mol, respectively. In addition, a significant reduction in the leaching efficiency of aluminum was caused by the hydrolysis reaction reinforced by the increase in MgSO4 concentration and temperature. The leaching kinetic data of IEP-Ca and IEP-Al was verified by the column leaching mass transfer process. There was a synchronous increase in the peak concentration of the outflow curve and leaching efficiency of calcium with the concentration of MgSO4 since IEP-Ca was easily leached. Therefore, as the leaching efficiency of calcium was already very high in the 0.20 mol/L MgSO4 leaching process, the leaching rate of calcium was limited by the leaching temperature and injection rate of MgSO4. For aluminum, the hydrolysis of Al3+ was promoted by increasing the MgSO4 concentration and the leaching temperature, thereby effectively reducing the content of aluminum in the leachate.

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Section: Leaching Kinetics Of Aluminummentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Leaching Behaviors of Calcium and Aluminum from an Ionic Type Rare Earth Ore Using MgSO4 as Leaching Agent

Qiu

Rao

et al. 2021

Minerals

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“…28 Oxidation of Ce(III) to Ce(IV) commonly occurs in the weathering process, and it is typically associated with the dissolution/precipitation, resulting in the formation of Fe−Mn−Ce oxide-bound components with low solubility and mobility. 29 Therefore, in this study, oxygen vacancy-driven Ce sulfation for enhancing the separation of REEs and transition metals (Fe and Mn) of the tailings is investigated. Mechanisms of selective transformation are systematically studied using in situ characterization, thermodynamic analysis, and density functional theory (DFT) calculation.…”

Section: Introductionmentioning

confidence: 99%

“…The low leaching efficiency during the ion-exchange process might result from the non-exchangeable REEs, especially the Fe–Mn–Ce oxide-bound components. − Among all REEs, Ce is the only element that can exist in the tetravalent state in nature . Oxidation of Ce(III) to Ce(IV) commonly occurs in the weathering process, and it is typically associated with the dissolution/precipitation, resulting in the formation of Fe–Mn–Ce oxide-bound components with low solubility and mobility . Therefore, in this study, oxygen vacancy-driven Ce sulfation for enhancing the separation of REEs and transition metals (Fe and Mn) of the tailings is investigated.…”

Section: Introductionmentioning

confidence: 99%

Insights into the Selective Transformation of Ceria Sulfation and Iron/Manganese Mineralization for Enhancing the Selective Recovery of Rare Earth Elements

Zhou

Xiao

Guo

et al. 2023

Environ. Sci. Technol.

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To cope with the urgent and unprecedented demands for rare earth elements (REEs) in sophisticated industries, increased attention has been paid to REE recovery from recycled streams. However, the similar geochemical behaviors of REEs and transition metals often result in poor separation performance due to nonselectivity. Here, a unique approach based on the selective transformation between ceria sulfation and iron/ manganese mineralization was proposed, leading to the enhancement of the selective separation of REEs. The mechanism of the selective transformation of minerals could be ascribed to the distinct geochemical and metallurgical properties of ions, resulting in different combinations of cations and anions. According to hardsoft acid-base (HSAB) theory, the strong Lewis acid of Ce(III) was inclined to combine with the hard base of sulfates (SO 4 2− ), while the borderline acid of Fe(II)/Mn(II) prefers to interact with oxygen ions (O 2-). Both in situ characterization and density functional theory (DFT) calculation further revealed that such selective transformation might trigger by the generation of an oxygen vacancy on the surface of CeO 2 , leading to the formation of Ce 2 (SO 4 ) 3 and Fe/Mn spinel. Although the electron density difference of the configurations (CeO 2−x -SO 4 , Fe 2 O 3−x -SO 4 , and MnO 2−x -SO 4 ) shared a similar direction of the electron transfer from the metals to the sulfate-based oxygen, the higher electron depletion of Ce (Q Ce = −1.91 e) than Fe (Q Fe = −1.66 e) and Mn (Q Mn = −1.64 e) indicated the higher stability in the Ce−O−S complex, resulting in the larger adsorption energy of CeO 2−x -SO 4 (−6.88 eV) compared with Fe 2 O 3−x -SO 4 (−3.10 eV) and MnO 2−x -SO 4 (−2.49 eV). This research provided new insights into the selective transformation of REEs and transition metals in pyrometallurgy and thus offered a new approach for the selective recovery of REEs from secondary resources.

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“…The use of (NH 4 ) 2 SO 4 and NH 4 HCO 3 has generated serious ammonia–nitrogen pollution. High ammonium–nitrogen contamination in both groundwater (3500–4000 mg/L) and surface water (80–160 mg/L) has been reported, , which leads to eutrophication and biodiversity decline in streams. To solve the above problems, nonammonia leaching agents, − such as magnesium sulfate, iron sulfate, and aluminum sulfate, and nonammonia precipitants, − such as sodium carbonate, magnesium oxide, and calcium oxide, have been widely studied.…”

Section: Introductionmentioning

confidence: 99%

Removal of Sulfate Ions from Calcium Oxide Precipitation Enrichment of a Rare Earth Leaching Liquor by Stirring Washing with Sodium Hydroxide

Fuguo

Lai

et al. 2021

ACS Omega

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The use of calcium oxide as a precipitant can achieve a nonammonia enrichment of a rare earth leaching liquor. However, an alkaline rare earth sulfate forms during the precipitation process, thus resulting in excessive SO 4 2− content in the mixed rare earth oxides. Therefore, a stirring washing process for precipitation enrichment, which was obtained from calcium oxide precipitation, was investigated using a sodium hydroxide solution. It was determined that the Gibbs free energy of the stirring washing reaction, which was calculated by a group contribution method, was between −60 and −300 kJ/mol, depending on the different rare earth elements. The above results indicated that the reaction was thermodynamically feasible. The optimum conditions of the washing process were obtained, namely, a feed ratio of 2.85, a liquid−solid ratio of 6.5 mL/g, a stirring washing temperature of 35 °C, and a stirring washing time of 20 min. Under the optimal conditions, the purity and the SO 4 2− content of the mixed rare earth oxides were 94.38% and 3.48%, respectively, and the stirring washing process with the sodium hydroxide solution had good recyclability. Moreover, the washing product was tested using thermogravimetry-differential thermal analysis (TG-DTA), X-ray diffraction (XRD), and scanning electron microscopy-energy-dispersive spectrometry (SEM-EDS), which verified that the stirring washing process with NaOH could effectively remove SO 4 2− from the precipitation enrichment into solution. On this basis, a new extraction process of the ion-adsorption-type rare earth ore by magnesium salt leaching−calcium oxide precipitation−sodium hydroxide stirring washing is proposed. This new process can eliminate the traditional aluminum-removal process and effectively reduces the rare earth loss in the process. It can also solve the problem of the excessive SO 4 2− content in the mixed rare earth oxides caused by the calcium oxide precipitation process. The research in this paper can have great significance for green, efficient extraction of the ion-adsorptiontype rare earth ore and the improvement of resource utilization.

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A discussion on the leaching process of the ion-adsorption type rare earth ore with the electrical double layer model

Cited by 42 publications

References 22 publications

Leaching Behaviors of Calcium and Aluminum from an Ionic Type Rare Earth Ore Using MgSO4 as Leaching Agent

Leaching Behaviors of Calcium and Aluminum from an Ionic Type Rare Earth Ore Using MgSO4 as Leaching Agent

Insights into the Selective Transformation of Ceria Sulfation and Iron/Manganese Mineralization for Enhancing the Selective Recovery of Rare Earth Elements

Removal of Sulfate Ions from Calcium Oxide Precipitation Enrichment of a Rare Earth Leaching Liquor by Stirring Washing with Sodium Hydroxide

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