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Addition of organic acids to dilute hydrochloric acid solution can improve the extraction of rare earth elements by single cationic extractants. However, the correlation between the chemical structure of organic acids and the extraction of REEs as well as the variation in equilibrium pH has not been elucidated. In this study, we investigated the extraction of Tb(III) from dilute HCl solutions containing an organic acid like formic, lactic, fumaric, or maleic acid. As extractants, single Cyanex 272, a mixture of Cyanex 272 and Alamine 336 (Ala336-Cy272), and an ionic liquid (ALi-Cy272) synthesized by Cyanex 272 and Aliquat 336 were used. The speciation of Tb(III) in dilute HCl solutions containing organic acids was analyzed. In extraction of Tb(III), organic acids showed two roles as complexing and buffering agent, which depended on the chemical structure of the acids. There was some difference in the extraction of Tb(III) between single Cyanex 272 and ionic liquid, ALi-Cy272. During extraction with ALi-Cy272, formic and lactic acid negatively affected the extraction of Tb(III). The fact that the chemical structure of organic acids affected the extraction of Tb(III) from dilute HCl solution by the studied extractants can provide important information on the selection of suitable extraction systems.

The recovery of valuable metals such as cobalt, nickel, and lithium from spent lithium-ion batteries (LIBs) has attracted much attention. In this study, a hydrometallurgical process for the recovery of high-purity lithium compounds like Li2CO3 and Li3PO4 from dust containing Li, Co, Ni, Cu, Fe, Mn, and Si produced during the smelting reduction of spent LIBs was investigated. The separation of Li over other metals from the dust was achieved by two methods. The first method was to leach metals from the dust with distilled water and then to precipitate the dissolved metal ions from the leaching solution at pH 10. The second one was to mix the dust with solid NaOH, following the dissolution of the mixture with distilled water. Optimum conditions for the second method were a 1:0.17 weight ratio of dust to NaOH, 50 g/L pulp density for 120 min at 22oC. These two methods resulted in a solution containing only Li(I) and Na(I). The precipitation of Li(I) to Li2CO3 from the leaching solution by Na2CO3 with the addition of acetone or ethanol was optimized a 1:0.5 molar ratio of Li(I) to Na2CO3, 6:5 volume ratio of solvent to Li(I) solution for 30 min at 22oC. Under the optimum conditions, the precipitation percentage of Li(I) was higher than 92.0% with above 99.0% purity. Additionally, using Na3PO4, 97.1 % Li(I) was precipitated from the leaching solution to Li3PO4 with 93.1% purity. An optimized process for the recovery of lithium compounds from the dust is proposed.

With increasing consumption of lithium-ion batteries (LIBs), recycling of spent LIBs has attracted much attention owing to their potential environmental impacts and metal values. In this work, a hy...

Numerical modeling for the safety-related equipment used in a nuclear power plant (i.e., cabinet facilities) plays an essential role in seismic risk assessment. A full finite element model is often time-consuming for nonlinear time history analysis due to its computational modeling complexity. Thus, this study aims to generate a simplified model that can capture the nonlinear behavior of the electrical cabinet. Accordingly, the distributed plasticity approach was utilized to examine the stiffness-degradation effect caused by the local buckling of the structure. The inherent dynamic characteristics of the numerical model were validated against the experimental test. The outcomes indicate that the proposed model can adequately represent the significant behavior of the structure, and it is preferred in practice to perform the nonlinear analysis of the cabinet. Further investigations were carried out to evaluate the seismic behavior of the cabinet under the influence of the constitutive law of material models. Three available models in OpenSees (i.e., linear, bilinear, and Giuffre-Menegotto-Pinto (GMP) model) were considered to provide an enhanced understating of the seismic responses of the cabinet. It was found that the material nonlinearity, which is the function of its smoothness, is the most effective parameter for the structural analysis of the cabinet. Also, it showed that implementing nonlinear models reduces the seismic response of the cabinet considerably in comparison with the linear model.

The recovery of valuable metals such as Co, Cu, and Ni from spent lithium-ion batteries has attracted much attention due to environmental issues and economic values. Separation of these metals from the synthetic metallic mixtures was investigated by employing nonaqeous solvent. In this work, the mixture of HCl in ethylene glycol (EG) and Aliquat 336 in kerosene was employed as nonaqeous solvents and the leaching conditions were optimized. Under the optimum condition, Ni was completely leached and remained in the EG phase with 99.8% purity. Meanwhile, the leaching percentage of Co(II) and Cu(II) was 62.3% and 18.3% and most of the two dissolved metal ions were extracted into Aliquat 336 phase. After complete stripping of Co(II) and Cu(II) from the loaded Aliquat 336 phase with 2.0 mol L−1 H2SO4, Cu(II) was selectively extracted over Co(II) by 0.1 mol L−1 Cynanex301 and then stripped by 50% aqua regia solution with >99.9% purity. The purity of Co(II) in the raffinate was 99.6%. Besides, Co from the leaching residue was selectively dissolved over Cu by 5.0 mol L−1 H2SO4 with 99.6% purity. A process was proposed for the separation of Co, Cu and Ni from metallic mixtures. The process showed some advantages in terms of the high purity of the metal solutions recovered and a decrease in the number of steps for the metal recovery. Thus, the application of this process to real operation can be considered.

This study presents the Probabilistic Seismic Demand Model (PSDM) and explores optimal intensity measures (IMs) for nuclear power plant (NPP) equipment when subjected to ground motions having high-...

Predicting the behavior of concrete in a Concrete-Filled Steel Tubular (CFST) column is challenging due to the sensitivity to input parameters such as the size of the cross-section, the material modeling, and the boundary conditions. The present paper proposes a new modified finite element model to predict the behavior and strength of a CFST subjected to axial compression. The development is based on the concrete damaged plasticity model, with its stress-strain relationship revised from the available model. The predicted accuracy of the modified model is verified via a wide range of experimental tests. The proposed model has more accuracy than the available models in predicting the ultimate compression strength. The results show good agreement with the test data, allowing its use in modeling CFST columns.

Lithium-ion batteries (LIBs) are employed in various electronic devices and industries. The recovery of valuable metals from spent LIBs has attracted much interest due to potential environmental is...

The dissolution behavior of Co, Ni, and Cu and the metallic mixture in acid solutions like HCl, H2SO4, CH3SO3H, and CH3COOH and their mixture with H2O2 was investigated. The effect of parameters su...

Ionic liquids have emerged in hydrometallurgy as potential extractants for metals. In this work, the interactions of ALiCY (R4N+A-) synthesized by Aliquat336 and Cyanex272, and a mixture of ALiCY and TBP, were analyzed using extraction data and FT-IR spectroscopy. Co(II) and Ni(II) were extracted from two HCl concentrations (1.0×10-4 and 6.8 mol·L-1) using ALiCY and its mixture with TBP. The extraction results indicated that ALiCY has a dual function, as a cationic extractant at low HCl concentration and an anionic extractant at high HCl concentration depending on the types of metal complexes. The addition of TBP to ALiCY had a negative effect on the extraction of Co(II) from the 6.8 mol·L-1 HCl, while the effect was negligible from the 1.010-4 mol·L-1 HCl. The solvation of R4N+ by TBP significantly affected the extraction behavior of ALiCY for metal ions. The formation of hydrogen bonding between TBP and Cyanex272 was verified. These findings shed light on the behavior and interaction occurring between bif-ILs and solvating extractants for the extraction of metals in acidic media.

Structural modification in the electrical cabinet is investigated by a proposed procedure that comprises of an experimental, analytical and numerical solution. This research emphasizes the linear dynamic analysis of the cabinet that is studied under the seismic excitation to demonstrate the real behavior of the cabinets in NPP. To this end, an actual electric cabinet is experimentally tested using an impact hammer test which reveals the fundamental parameters of the cabinet. The Frequency-domain decomposition (FDD) method is used to extract the dynamic properties of the cabinet from the experiment which is then used for numerical modeling. To validate the dynamic properties of the cabinet an analytical solution is suggested. The calibrated model is analyzed under the floor response obtained from the Connecticut nuclear power plant structure excited by Tabas 1978 (Mw 7.4) earthquake. Eventually, the grouping effect of the cabinets is proposed which represents the influence on the dynamic modification. This grouping of the cabinets is described more sophisticatedly by the theoretical understating, which results in a significant change in the seismic response. Considering the grouping effects will be helpful in the assessment of the real seismic behavior, design, and performance of cabinets.

This study investigates the fragility assessment of the electrical cabinet facility, a steel structural form that exhibits behavior and response patterns distinct from the normal structure. To eval...

This study provides an insight of the nonlinear behavior of the Offshore Wind Turbine (OWT) structure using the distributed plasticity approach. The fiber section beam-column element is applied to construct the finite element model. The accuracy of the proposed model is verified using linear analysis via the comparison of the dynamic characteristics. For collapse risk assessment of OWT, the nonlinear effects considering the earthquake Incident Angle (IA) have been evaluated first. Then, the Incremental Dynamic Analysis (IDA) has been executed using a set of 20 near-fault records. Lastly, fragility curves are developed to evaluate the vulnerability of structures for different limit states. Attained results justify the accuracy of the proposed approach for the structural response against the ground motions and other environmental loads. It indicates that effects of static wind and wave loads along with the earthquake loads should be considered during the risk assessment of the OWT structure.

This paper proposes a simplified approach for assessing and predicting the seismic risks for electrical cabinets in nuclear power plants (NPPs). The method is a combination of fragility analysis an...

Fe(III) can be easily extracted from weak acidic solutions by organophosphorus extractants, but stripping a large amount of Fe(III) from the loaded extractants is very difficult. The extraction and stripping of Fe(III) from 2 pH chloride and sulfate solutions was performed with ionic liquids(ILs) and organophosphorus acidic extractants, and the behaviors compared. As ionic liquids, two succinimides ([N88SA][C4min] and ([N88SA][C4Py]) were used, and bi-functional ionic liquids (Bif-ILs) synthesized from Aliquat336 and the organophosphorus acids Cyanex272, D2EHPA, and PC88A were employed. The extraction of Fe(III) by the ILs and extractants employed in this work was in the following order: organophosphorus extractants > Bif-ILs > succinimide ILs. The extraction of Fe(III) by succinimide ILs and Bif-ILs was higher from the chloride solution than from the sulfate one, while the nature of the medium had little effect on the extraction of Fe(III) by the organophosphorus extractants. FT-IR spectra confirmed the ion exchange mechanism of Fe(III) by the succinimide ILs. There was little difference in the stripping of Fe(III) by H2SO4 from the loaded Bif-ILs and the organophosphorus acids. However, stripping of Fe(III) from the loaded Bif- ILs using HCl did not readily occur. Fe(III) was readily stripped from the loaded [N88SA][C4min] and [N88SA][C4Py], and the HCl solution was more effective for stripping than H2SO4. [N88SA][C4min] is considered a promising new extractant for the recovery of Fe(III) based on its Fe(III) extraction and stripping behavior from weak acidic solution. (Received September 18, 2019; Accepted October 29, 2019)

This study presents a simple, efficient, accurate method for nonlinear time-history earthquake analysis of spatial steel frames. The proposed new fiber plastic hinge method simulating only one element for each member captures the time-history dynamic behavior of steel frames as accurately as sophisticated plastic zone methods. Stability functions and the geometric stiffness matrix are employed for predicting the second-order effects that aim to minimize computational time and computer resources. Residual stresses are considered through two fiber plastic hinges by assigning initial stress values. A numerical integration procedure using Newmark integration combined with the Newton-Raphson balanced iteration algorithm is developed to find a solution to nonlinear dynamic equilibrium equations of the structural system. Shear deformation effects are also considered in the dynamic analysis. The proposed software, named Direct Advanced Analysis and Design (DAAD), is proved to be accurate and reliable as compared with the analysis results generated by expensive commercial Finite Element Analysis (FEA) software packages. The proposed DAAD program can be improved for performance-based direct design and analysis., Earthquakes; Fiber plastic hinges; Geometric nonlinearity; Inelasticity; Stability functions; Steel frames.

An approach for collapse risk assessment is proposed to evaluate the vulnerability of electric cabinet in nuclear power plants. The lognormal approaches, namely maximum likelihood estimation and linear regression, are introduced to establish the fragility curves. These two fragility analyses are applied for the numerical models of cabinets considering various boundary conditions, which are expressed by representing restrained and anchored models at the base. The models have been built and verified using the system identification (SI) technique. The fundamental frequency of the electric cabinet is sensitive because of many attached devices. To bypass this complex problem, the average spectral acceleration (Sa¯) in the range of period that cover the first mode period is chosen as an intensity measure on the fragility function. The nonlinear time history analyses for cabinet are conducted using a suite of 40 ground motions. The obtained curves with different approaches are compared, and the variability of risk assessment is evaluated for restrained and anchored models. The fragility curves obtained for anchored model are found to be closer each other, compared to the fragility curves for restrained model. It is also found that the support boundary conditions played a significant role in acceleration response of cabinet. Keywords: Fragility curve, Seismic intensity measure, System identification, Lognormal assumption, Average spectral acceleration, Linear regression

Site response is a function of the soil profile, and the probable distribution of the soil profile has a significant effect on the seismic site response. In the present study, the influence of random variations in soil characterizations on the site response is investigated using different probabilistic distributions. The important characteristics of the local soil, corresponding to the layering, the shear wave velocity ( V s ), the decrease in the nonlinear modulus, and the damping (MRD) curves, are considered when carrying out these random variations. Stochastic processes are generated by using different distribution models and keeping in mind the effect of the coefficients of the variations. In this research, a proposed procedure is developed and coded to perform the variations in soil characterizations. The coding of this new procedure is based on the original SHAKE91 framework. However, instead of using the fixed soil properties and profile, the uncertainties of the MRD curves, the layer thickness, and V s are generated as the input data. This analysis shows that the use of median V s , obtained from all the possible inputs under the different stochastic processes, yields good agreements with the baseline profile. Modelling the variabilities in the layering and the V s profile is seen to have a slight effect on the performance of the site response. Additionally, the results of these analyses indicate that the variabilities in nonlinear soil properties have a significant impact on the median surface response spectrum and the amplification spectrum of the surface motions.

Cabinet facility is known as a high-frequency nonstructural component, and its failure is directly affected by dynamic characteristics of ground motions (i.e., frequency content, amplitude, and duration). This study aims to investigate the seismic vulnerability of a nonstructural component in the nuclear power plant (NPP) induced by the predominant frequency of the ground motions. Time history analysis is performed for eighty ground motions of low- and high-frequency motions. The results indicate that the high-frequency ground motions significantly increase the peak acceleration at the top of the cabinet. In contrast, the low-frequency content motions have less impact on structural seismic behavior.

The geotechnical properties of soil deposit and the variability associated with their probable distributions have a profound impact on the seismic response of a site. In the present work, t...

The study investigates the collapse probability of a cabinet facility with a tuned mass damper (TMD) subjected to high- and low-frequency earthquakes. For this aim, a prototype of the cabinet in Korea is utilized for the numeric simulation. The accuracy of the finite element model is evaluated via the impact hammer tests. To mitigate the seismic response of the structure, a TMD system is developed whose properties are designed based on the outcomes from the modal analysis (i.e., modal frequencies and mode shapes). Furthermore, the influences of earthquake frequency contents on the seismic response are evaluated. The numeric analyses are conducted using a series of eighty earthquakes that are classified into two groups corresponding to low- and high-frequency motions. Finally, fragility curves are developed for the cabinet subjected to different ground motion sets. The results quantify the seismic vulnerability of the structure and demonstrate the influences of earthquake frequency contents and the vibration control system on the seismic response of the cabinet.