查看更多>>摘要：Nickel metal hydride batteries find extensive use in many electronic devices. They contain a small amount of rare earth elements, such as, lanthanum and neodymium, which can be recovered from waste batteries, and reused. Hollow fiber supported liquid membranes (HFSLM) have been used for separation of different metal ions. In this work, a CFD model has been developed for a HFSLM to study the separation of lanthanum ion (La+3) and neodymium ion (Nd+3) from an aqueous solution. The model considers the effect of pH on distribution coefficient (D-M), which is a function of hydrogen ion (H+) concentration, and has a significant effect on extraction efficiency. The model was validated with the experimental data. An empirical model was fitted with the simulation data, and the parameters were optimized for the effective separation of La+3 and Nd+3. The maximum extraction of Nd+3 was predicted to be 44.97%, whereas extraction of La+3 was estimated to be 3.39%, at the optimized conditions of flow rate: 118.96 ml/min, feed pH: 3.41, and [PC88A]: 41.63 mol/m(3), in once-through mode. The proposed CFD model could be helpful in design as well as, scale-up of HFSLM for separation of metal ions, by changing the design and process parameters.
Alizadeh, ShahabAbdollahy, MahmoudDarban, Ahmad KhodadadiMohseni, Mehdi...
11页
查看更多>>摘要：The extraction behavior of two lanthanides (La3+ and Y3+) in the nitric acid solution was studied using a bifunctional ionic liquid, namely Trihexyl-tetradecyl-phosphonium Decanoate ([P-6,P-6,P-6,P-1,P-4] [Decanoate]). On comparative study on D2EHPA as a molecular extractant, the ionic liquid revealed remarkably higher extraction capacity of the total are earth elements. The ionic liquid had a separation factor for La/Y smaller than that of the molecular extractant. A high yttrium extraction with an efficiency of > 99% was observed for both extractants, even in low concentrations. The highest efficiency of D2EHPA (20%) equaled 75.04% in the extraction of lanthanum, while this magnitude was > 99% for lanthanum extraction by the ionic liquid. In this study, the Density Functional Theory (DFT) connected to Born Haber Thermodynamics was used along with the solvent effect, imported by the Conductor-like Screening Model (COSMO), for confirming and interpreting the selectivity results, which were observed in the laboratory during the extraction of lanthanum and yttrium. Calculation of the difference in the energy levels of the molecular orbitals of [P-6,P-6,P-6,P-1,P-4] [Decanoate] in the extraction of the neutral complexes of [La.(NO3)(3). (H2O)(3)] delta E-orbital = 0.16 eV) and [Y.(NO3)(3). (H2O)(2)] (delta E-orbital = 0.17 eV) with the neutral or ion pair exchange has shown that this ionic liquid was more efficient than D2EHPA with a cation exchange mechanism in the extraction of the ionic complexes of these elements.
Singh, PritamNikoloski, Aleksandar N.Phiri, Tina Chanda
14页
查看更多>>摘要：The mining industry faces a number of challenges that include rapid depletion of high-grade deposits, high energy cost for metal production, and growing environmental concerns associated with mining waste disposal. Copper slag is one of the mining wastes that is raising growing concern due to the huge volumes being produced and dumped annually worldwide. These huge quantities of slag not only cause environmental pollution and space problems for disposal, but they also waste valuable copper and cobalt. This is increasingly important due to the growing demand for these metals in emerging technologies, potentially resulting in a supply deficit from conventional mining production. To address these challenges, recycling and repurposing of copper slag waste using innovative technologies should be considered, creating a resource for a circular economy. This paper presents a review of copper slag production and its potential as a world resource for cobalt and copper metals. An overview of copper and cobalt production from ore reserves, and of global demand and supply risks for these metals is presented. The potential benefits of reprocessing copper slag waste using the circular economy model are discussed. This paper demonstrates that applying the circular economy principles to the copper slag waste has the potential to create additional economic value, improve the energy efficiency of the metal production, increase the supply of critical metals, and reduce the impacts of metal production on the environment.
查看更多>>摘要：In this research, the leaching of complex gold ore was studied using cyanide and glycine. In the absence of glycine, the gold dissolution increases from 6.47 to 62.21% with increasing the cyanide concentration from 250 to 4500 g/t. The ore contains sulfide minerals and base metals, such as copper, zinc, and silver, which are high cyanide consumers. At 2000 g/t cyanide concentration, the gold dissolution significantly increases from 30 to 92% with adding 0.5 mol/L of glycine. A further increase in the glycine concentration has no significant effect on the dissolution of gold. At 2000 g/t cyanide and 0.5 mol/L glycine concentrations in the absence of H2O2, the dissolution of gold is 78%, which increases to 88% and 93% with increasing the H2O2 concentration to 1 and 1.5%, respectively. The solid content is very effective in the range of 20-25%. Further increases in the solid content to 30, 35, and 40% do not have a significant effect on the gold dissolution. When only glycine is in the system, the gold dissolution is very low, and when only cyanide is in the system, the gold and copper dissolutions are almost the same. The solubility of copper in the presence of cyanide and glycine is the same, but the solubility of gold in cyanide is much higher than glycine.
查看更多>>摘要：Combination of the alpha-hydroxyoxime and the carboxylic acids results in synergistic extraction of nickel and cobalt and exhibits excellent performance of separating nickel and cobalt from manganese, magnesium and calcium, but they have the drawbacks of slow nickel stripping kinetics. In this study, trioctylphosphine oxide (TOPO), as an accelerator, was used to improve the nickel stripping kinetics of the Mextral 6103H/naphthenic acid system. The results showed that the addition of 0.35 M TOPO to 0.35 M Mextral 6103H/0.5 M naphthenic acid system significantly improved the nickel stripping kinetics. After mixing for 3 min, 96% stripping efficiency was obtained with 15 g/L H2SO4 at an O/A ratio of 1:1 and 25 degrees C. The extraction pH isotherms revealed that more than 99.0% copper, 99% cobalt, 97% nickel and 86% zinc were extracted at pH 5.5, and only 6% manganese, 0.08% magnesium and 0.24% calcium were co-extracted. At pH 5.0, 87% calcium, 96% manganese and 97% magnesium can be scrubbed, resulting in 5.3 mg/L manganese and less than 0.5 mg/L magnesium and calcium remained in the scrubbed organic solution. Full stripping of nickel and cobalt could be achieved in two stages with 50 g/L nickel and 150 g/L H2SO4 at an O/A ratio of 10:1 and 25 degrees C. Thus, compared with TBP, TOPO was more efficient for improving the nickel stripping kinetics at room temperature, which can reduce the power consumption and lead to clear production.
查看更多>>摘要：In the light of the adsorption difference of cationic collectors on quartz and apatite, an additional hydrogen bond functional group can be introduced into the traditional collector molecule-dodecylammoniu m acetate (DDA) to achieve high-efficient separation of minerals. In this study, a new surfactant-N-(2-hydroxy-1, 1-dimethylethyl) dodecylamine (HDMEA) was synthesized in ou r laborator y and acted as a new-type amine collector in the reverse flotation separation of apatite from quartz. The results of micro-flotation tests indicated that the separation performance of HDMEA was significantly better than that of DDA . When the concentration of HDMEA was 20 mg/L at pH 6.43, the apatite with 38.57% grade and 95.8% recover y could be achieved in mixed-flotation tests. The adsorption mechanism of DDA and HDMEA on quartz and apatite was comparably explored by the mea-surements of zeta potential , FTIR, contact angle, and AFM as we l l as the DFT calculations. These results demonstrated that improving the hydrogen bonds adsorption on quartz (by -NH-and -OH groups) and increasing the steric-hindrance effect on apatite help to achieve efficient flotation separation of quartz and apatite.
查看更多>>摘要：Recent studies on calcite have shown that newly precipitated clusters of amorphous calcium carbonate (ACC) and vaterite in pulp change the inherent reactivity of the calcite surface. The flotation recovery and surface zeta potential of calcite undergo rapid changes during the initial reaction time but are slightly altered after 60 min. In order to further understand the adverse effects of newly precipitated CaCO3 on the flotation of calcite, the relationship between the recrystallization process of nascent calcium carbonate (CaCO3) and the flotation behavior of calcite was explored under different time conditions in this study. Accordingly, during the recrystallization process, the intensity of the chemical reaction between ACC-vaterite-calcite and hexametaphosphate (SH) was found to gradually weaken through the flotation test, SEM, XRD and FTIR. Furthermore, due to the difference in crystal structure, ACC and vaterite were shown to strengthen the reactivity of SH and Ca2+ on the surface of calcite in flotation through the zeta potential test and X-ray photoelectron spectroscopy (XPS), thereby weakening the ability of oleate (OL-) in collecting the mineral.
查看更多>>摘要：Plenty of research articles on developing methods to recover metals from secondary sources have been published. These methods are optimized for a specific source and have poor reproducibility when used for different sources. However, the composition of the source changes with time, manufacturer, and geography, making designing the recovery process a tedious endeavor. A modeling framework that captures the source variation and suggests the process parameters was developed and employed to design a process for copper recovery from the printed circuit board (PCB). Data collected from 23-research articles was visualized using four-dimensional plots. Plots show that the leaching time required for Cu recovery is inversely proportional to hydrogen peroxide concentration, acid concentration, and source % Cu. Recovery is amplified and faster when all these parameters are set to high value, which may not be feasible commercially. Five supervised machine-learning algorithms (support vector machine, random forest, gradient boost machine, XG Boost, and AdaBoost) were trained on 1200 data points as classification and regression problems and validated using a 10-fold cross-validation procedure. Models were tested on 120 data points and compared for predicting accuracy; the gradient boost machine model performs best with an MAE of 10.83% and an F1 score of 0.72. Feature importance analysis based on LIME and permutation importance is used to evaluate the contribution of each feature on recovery, and reduced parameter ranges for high recovery are obtained. Our modeling framework is generic, which can be used for designing any recovery process.
Abdollahy, MahmoudKhalesi, Mohammad RezaRezai, BahramKhatir, Mehdi Zakeri...
7页
查看更多>>摘要：In this study, fluorine ion was applied as a chelating agent to separate selectively neodymium ion from aluminum ion by ion flotation. The interactions of neodymium and aluminum ions with fluorine ions at different fluorine concentrations and pHs were investigated to determine species ions formed in solution. The results showed that the presence of fluorine ions increased the selective separation of neodymium ion, enhancing the selectivity coefficient during the process. A decrease in the selectivity coefficient was obtained with increasing the concentration of fluorine ion. As the fluorine ion concentration increased from 3.5 to 10 mM, there was an increase in the selectivity coefficient from 2.91 to 30.2 and then decreased using more fluorine. Selective ion flotation results indicated that neodymium ion recovery was higher than that of aluminum ions, indicating the ion recovery order based on the enhancing order of crystal ionic radius. Also, the scanning electron microscope (SEM), energy-dispersive X-ray spectroscopy (EDAX) and Fourier-transform infrared spectroscopy (FTIR) analyses results confirmed higher interaction of fluorine ions with neodymium ions compared to that of the aluminum ions in the solution.
查看更多>>摘要：Extracting mineral ores to produce mineral concentrates and finally metals that enter the value chains of different sectors is a waste intensive activity. In particular, mineral processing activities generate yearly and globally several billion tons of wastes called tailings. Tailings storage is associated with significant environmental risks due to different sources such as releases to groundwater. Yet, these environmental impacts are poorly taken into account in the environmental life cycle assessment of a concentrate or metal production, in particular due to a lack of representative data in the inventory.This paper aims at coupling geochemical modelling geochemical modelling with life cycle assessment to quantify releases from tailings and the associated environmental impacts. In the present work, reactive transport modelling was implemented to quantify more accurately short-term (100-year timeframe) and long-term (10,000 year-timeframe) tailings releases. Reactive transport modelling allows modelling and estimating the distributions in space and in time of chemical reactions occurring in a specific environment. The resulting tailings releases are compared with those calculated through the approach, based on a first order law of kinetics, used in the ecoinvent database. The results from the ecoinvent approach are calculated both with generic and site specific parameters. These different approaches are applied on the case-study of a polymetallic sulphidic ore from a mine in Northern Europe.The tailings releases obtained through the different approaches differ. Overall, the reactive transport model leads to quantities released at both short-term and long-term timeframes being smaller than those calculated with the ecoinvent approach. As a result, the impacts on ecotoxicological and toxicological categories show differences between two to eight orders of magnitude. Each approach used to model the tailings releases differ in the nature and amount of data needed as well as in the sophistication of the model used. While the approach based on reactive transport modelling is exhaustive and presumably provides a more accurate prediction for the releases from tailings, it also requires massive computational resources and much larger volumes of data, some of which being difficult to obtain on-site. Consequently, a consensus has to be found between the complexity of the model used, the data availability and the expected reliability of the results.
NSTL
Elsevier