Isoconversional kinetic analysis of decomposition of bastnaesite concentrates with calcium hydroxide

Cen, Peng; Bian, Xue; Wu, Wenyuan

doi:10.1016/j.jre.2020.01.006

Cited by 8 publications

(5 citation statements)

References 52 publications

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“…Mechanism Analysis of Ce(III) Not being Oxidized to Ce(IV). The reason why Ce(III) was not oxidized to Ce(IV) is the following three mechanisms: [1] cerium oxide underwent carbothermal reduction reactions to reduce Ce(IV) to Ce(III).…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…According to thermodynamics calculation and analysis, the carbothermal reduction reactions 4 and 5 can be carried out at 1100 °C but reaction 6 cannot be carried out at 1200 °C, and therefore, mechanism [2] is excluded; reactions 7 and 8 are thermodynamically easy. Therefore, mechanisms [1] and [3] may coexist.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…Bastnaesite (REFCO 3 ) is one of the most critical light rare earth resources and provides approximately 70% rare earth production in China and also in the world. , The oxidative roasting hydrochloric acid leaching process is a mature industrial process of decomposing bastnasite concentrate . Bastnaesite can be easily decomposed to rare earth oxides during the roasting process .…”

Section: Introductionmentioning

confidence: 99%

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Nonoxidative Microwave Radiation Roasting of Bastnasite Concentrate and Kinetics of Hydrochloric Acid Leaching Process

Zheng

Cui

et al. 2020

ACS Omega

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Herein, a new clean extraction technology for the decomposition of bastnasite concentrate by utilizing the microwave radiation is proposed, which prevented Ce(III) from being oxidized to its tetravalent form. The process includes microwave radiation roasting to nonoxidatively decompose the bastnasite concentrate, mechanism analysis of Ce(III) not being oxidized to Ce(IV), hydrochloric acid leaching of the nonoxidative roasted ore, and kinetics analysis of the leaching process. The experiments were carried out concentrating on the effect of roasting temperature and holding time on the decomposition rate of the bastnasite concentrate and the oxidation rate of cerium and the effect of acidity, liquid–solid ratio, leaching temperature, and stirring rate on the leaching kinetics of the nonoxidative roasting ore. When the roasting temperature is 1100 °C, the holding time is 20 min, and the m (C)/ m (REFCO 3 ) ratio is 0.2, the results show that the leaching efficiency of rare earths can reach 85.45% under the conditions 3 mol/L HCl, 90 °C, 60 min, 9 mL/g liquid–solid ratio, and 300 rpm stirring rate. The X-ray diffraction and scanning electron microscopy analyses of the samples before and after acid leaching show that the rare earth oxides were completely leached and Ce(III) was not oxidized to its tetravalent form. The apparent activation energies of leaching rare earths were calculated as 14.326 kJ/mol, and the HCl leaching process can be described by a new variant of the shrinking-core model, in which both the interfacial transfer and the diffusion through the product layer influenced the reaction rate. Furthermore, a semiempirical rate equation was created to describe the leaching process of the nonoxidative roasted ore.

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Section: ■ Results and Discussionmentioning

confidence: 99%

Section: ■ Results and Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Nonoxidative Microwave Radiation Roasting of Bastnasite Concentrate and Kinetics of Hydrochloric Acid Leaching Process

Zheng

Cui

et al. 2020

ACS Omega

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“…It could be seen from the figure that pure TPU has two degradation peaks, and TPU/APP/MIT composites showed three degradation peaks, indicating that the reaction was a three‐step reaction, which were the degradation of hard segment, soft segment, and carbon layer of polyurethane, respectively. Pyrolysis kinetics analysis using Coats–Redfern for each of the three stages 26 …”

Section: Resultsmentioning

confidence: 99%

“…Pyrolysis kinetics analysis using Coats-Redfern for each of the three stages. 26 The Arrhenius equation for the temperature dependence of the reaction rate was commonly used for thermal analysis reactions. The Arrhenius equation was expressed as…”

Section: Pyrolysis Kinetics Of Tpu/app/mit Compositesmentioning

confidence: 99%

Metallurgical solid waste modified thermoplastic polyurethane composites: The thermal stability and combustion properties

Yang

Liu

Tao

et al. 2022

J of Applied Polymer Sci

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As a kind of bulk industrial solid waste, the massive accumulation of iron tailings has caused serious waste of resources and environmental pollution. In this study, a silane coupling agent (KH550) was used to modify the surface of iron tailings to produce MIT, and it was compounded with ammonium polyphosphate (APP) on thermoplastic polyurethane (TPU) to prepare a series of TPU/APP/MIT composites. Thermogravimetric (TG), cone calorimetric (CCT), thermogravimetric infrared, scanning electron microscopy, and Raman techniques were also used to analyze the combustion performance, smoke toxicity, and microscopic morphology. The TG test results showed that the compounding of APP and MIT significantly improved the residual carbon value of TPU composites at 700 C. CCT test results showed that the TPU/APP/MIT composites exhibited excellent flame retardancy and smoke suppression. Compared with pure TPU, PHRR, THR, and TSR of TPU/APP15/MIT10 composite decreased by 85.56%, 87.83%, and 86.17%, respectively, the peak release rates of CO and CO 2 decreased by 69.26% and 90.34%, respectively. The above studies showed that APP and MIT have excellent flame retardant and smoke suppression effect on TPU materials, providing more opportunities for the study of TPU composites and metallurgical solid waste utilization.

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Reaction characteristics and kinetics of phosphogypsum decomposition via synergistic reduction effect of composite reducing agent

Liu

Chen

et al. 2022

J Mater Cycles Waste Manag

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Isoconversional kinetic analysis of decomposition of bastnaesite concentrates with calcium hydroxide

Cited by 8 publications

References 52 publications

Nonoxidative Microwave Radiation Roasting of Bastnasite Concentrate and Kinetics of Hydrochloric Acid Leaching Process

Nonoxidative Microwave Radiation Roasting of Bastnasite Concentrate and Kinetics of Hydrochloric Acid Leaching Process

Metallurgical solid waste modified thermoplastic polyurethane composites: The thermal stability and combustion properties

Reaction characteristics and kinetics of phosphogypsum decomposition via synergistic reduction effect of composite reducing agent

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