Exothermic processes in mixtures of TBP with nitric acid

Nazin, E. R.; Zachinyaev, G. M.; Белова, Е. В.; Tkhorzhnitskii, G. P.; Myasoedov, Β. F.

doi:10.1134/s1066362217050125

Cited by 9 publications

(2 citation statements)

References 8 publications

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“…At the studied temperatures (35–55 °C for a maximum of 2 h), the TBP–HNO 3 complex was expected to be stable. , However, careful safety precautions must be taken while handling this system because, in a pressure vessel, there is a risk of exothermic reactions between TBP and HNO 3 . Depending on the pressure, acid concentration, and residence time, the onset temperature for exothermic self-accelerating oxidation processes in TBP–HNO 3 mixtures is 117 °C and potentially lower depending if alcohols are present, which could result in hazardous reactions under certain reaction conditions. , As such, particular care and caution must be taken to ensure that experiments are carried out within safe operating parameters.…”

Section: Methodsmentioning

confidence: 99%

Aeriometallurgical Extraction of Rare Earth Elements from a NdFeB Magnet Utilizing Supercritical Fluids

Zhang¹,

Anawati²,

Yao³

et al. 2018

ACS Sustainable Chem. Eng.

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There is a global need for efficient and environmentally sustainable processes to close the life cycle loop of waste electrical and electronic equipment (WEEE) through recycling. Conventional WEEE recycling processes are based upon pyrometallurgy or hydrometallurgy. The former is energy-intensive and generates greenhouse gas (GHG) emissions, while the latter relies on large volumes of acids and organic solvents, thus generating hazardous wastes. Here, a novel “aeriometallurgical” process was developed to recycle critical rare earth elements, namely, neodymium (Nd), praseodymium (Pr), and dysprosium (Dy), from postconsumer NdFeB magnets utilized in wind turbines. The new process utilizes supercritical CO2 as the solvent, which is safe, inert, and abundant, along with the tributyl-phosphate–nitric acid (TBP–HNO3) chelating agent and 2 wt % methanol as a cosolvent. Nd (94%), Pr (91%), and Dy (98%) extraction was achieved with only 62% iron (Fe) coextraction and minimal waste generation. Fundamental investigations into the extraction mechanism demonstrated that metal ion charge has an important impact on the extraction efficiency. Fundamental investigations indicate that extraction proceeds by corrosion of the magnet particle’s surface layer. This work demonstrates that supercritical fluid extraction would find widespread applicability as a cleaner, a more sustainable option to recycle value metals from end-of-life products to enable the circular economy.

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Section: Methodsmentioning

confidence: 99%

Aeriometallurgical Extraction of Rare Earth Elements from a NdFeB Magnet Utilizing Supercritical Fluids

Zhang¹,

Anawati²,

Yao³

et al. 2018

ACS Sustainable Chem. Eng.

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“…Smitha et al reported the reaction of TBP with nitric acid at different acid concentrations [12][13][14][15]; the influences of diluents on the reactions and the behaviors of heat emission were also studied previously [5,[16][17][18][19][20][21][22][23]. Nazin et al reported thermal explosions in mixtures of TBP with nitric acid [14,24]. And Gordon et al studied the decomposition of red oil by simulating these accidents conditions experimentally [1,7].…”

Section: Introductionmentioning

confidence: 99%

Theoretical Study on the Mechanism for the Formation of Nitro Compounds in Red Oil

Tian

Tang

et al. 2020

Journal of Chemistry

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The mechanisms involved in reactions between methane, n-hexane, n-butanol, cyclohexane, and nitric acid were explored by density functional theory calculations. All the calculations in gas phase and n-tributyl phosphate (TBP) solvent were performed at the B3LYP/6–311++G ∗ ∗ and CCSD(T)/6–311++G ∗ ∗ levels of theory. The results showed that TBP has an important effect on the reactions between nitric acid and alkanes or butanol. The reactions were considered as that the radicals (·NO2 and ·NO3 radicals are formed via the HNO3 decomposition under irradiation) initiate the H-atom depletion of the reactants (R), and the produced radicals in red oil combine with ·NO2 radical to form the nitro compounds spontaneously. The rate constants of reactions R + ·NO2 and R + ·NO3 differ substantially, the rate constants of the latter being much larger than those of the former. In the reactions of R + ·NO3, the transition states and products are 20 kJ/mol and 100 kJ/mol or more stable than the reactants, respectively, but the reactions of R + ·NO2 need to overcome energy barriers over 25 kJ/mol. The formations of products mainly depend on the reactions of R + ·NO3. For the same type of alkanes (either chain or cyclic ones), the lower the relative stabilities of carbon-centered radicals are, the more reactive the alkanes are. Cyclohexane is the most competitive species, followed by n-butanol, n-alkanes, and methane which are the least competitive.

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Thermal stability of the extraction system “TODGA in Isopar M with n-decanol” at above atmospheric pressure

Skvortsov

Smirnov

Белова

2020

J Therm Anal Calorim

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Exothermic processes in mixtures of TBP with nitric acid

Cited by 9 publications

References 8 publications

Aeriometallurgical Extraction of Rare Earth Elements from a NdFeB Magnet Utilizing Supercritical Fluids

Aeriometallurgical Extraction of Rare Earth Elements from a NdFeB Magnet Utilizing Supercritical Fluids

Theoretical Study on the Mechanism for the Formation of Nitro Compounds in Red Oil

Thermal stability of the extraction system “TODGA in Isopar M with n-decanol” at above atmospheric pressure

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