Subjects -> METALLURGY (Total: 58 journals)
 Showing 1 - 10 of 10 Journals sorted alphabetically Acta Metallurgica Slovaca Advanced Device Materials       (Followers: 3) American Journal of Fluid Dynamics       (Followers: 48) Archives of Metallurgy and Materials       (Followers: 9) Asian Journal of Materials Science       (Followers: 5) Canadian Metallurgical Quarterly       (Followers: 20) Complex Metals       (Followers: 2) Corrosion Communications Energy Materials : Materials Science and Engineering for Energy Systems       (Followers: 19) Handbook of Magnetic Materials       (Followers: 2) Indian Journal of Engineering and Materials Sciences (IJEMS)       (Followers: 10) International Journal of Metallurgy and Alloys       (Followers: 3) International Journal of Metals       (Followers: 6) International Journal of Minerals, Metallurgy, and Materials       (Followers: 8) International Journal of Mining and Geo-Engineering Ironmaking & Steelmaking       (Followers: 4) ISIJ International - Iron and Steel Institute of Japan       (Followers: 23) JOM Journal of the Minerals, Metals and Materials Society       (Followers: 32) Journal of Advanced Joining Processes Journal of Central South University       (Followers: 1) Journal of Cluster Science Journal of Iron and Steel Research International       (Followers: 7) Journal of Materials & Metallurgical Engineering       (Followers: 1) Journal of Materials Processing Technology       (Followers: 19) Journal of Metallurgical Engineering       (Followers: 2) Journal of Sustainable Metallurgy       (Followers: 3) Materials Science and Metallurgy Engineering       (Followers: 7) Metallurgical and Materials Engineering Metallurgical and Materials Transactions A       (Followers: 41) Metallurgical and Materials Transactions B       (Followers: 30) Metallurgical and Materials Transactions E       (Followers: 2) Metallurgical Research & Technology Metallurgical Research and Technology       (Followers: 6) Metallurgy and Foundry Engineering       (Followers: 1) Mining, Metallurgy & Exploration Powder Diffraction       (Followers: 1) Powder Metallurgy       (Followers: 33) Powder Metallurgy and Metal Ceramics       (Followers: 7) Powder Metallurgy Progress       (Followers: 5) Rare Metals       (Followers: 2) Revista de Metalurgia Revista del Instituto de Investigación de la Facultad de Ingeniería Geológica, Minera, Metalurgica y Geográfica Revista Remetallica Russian Metallurgy (Metally)       (Followers: 4) Science and Technology of Welding and Joining       (Followers: 4) Soldering & Surface Mount Technology       (Followers: 1) Stainless Steel World       (Followers: 17) Transactions of the IMF       (Followers: 14) Transactions of the Indian Institute of Metals       (Followers: 4) Tungsten Universal Journal of Materials Science       (Followers: 1) Welding in the World       (Followers: 4) Welding International       (Followers: 7) Вісник Приазовського Державного Технічного Університету. Серія: Технічні науки
Similar Journals
 Journal of Sustainable MetallurgyNumber of Followers: 3      Hybrid journal (It can contain Open Access articles) ISSN (Print) 2199-3823 - ISSN (Online) 2199-3831 Published by Springer-Verlag  [2469 journals]
• Acid-Free Leaching Nickel, Cobalt, Manganese, and Lithium from Spent
Lithium-Ion Batteries Using Fe(II) and Fe(III) Solution

Abstract: End-of-life lithium-ion batteries (LIBs) have received unprecedented consideration because of their potential environmental pollution and the value of decisive metal supplies. The dosage of over-stoichiometric amounts of acids, including all kinds of organic or inorganic acids, may result in corrosion of the equipment or production of toxic and harmful gases. Herein, an unconventional acid-free method—salt leaching to extract Ni, Co, Mn, and Li from a spent LiNi0.5Co0.2Mn0.3O2 cathode material using Fe(II) (reductant reagent) and Fe(III) (precipitation) is proposed. Under the condition with 0.2 mol/L Fe2(SO4)3, 0.36 mol/L FeSO4, 40 min, and 90 °C, the leaching efficiencies of Ni, Co, Mn, and Li are all higher than 96%. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM) characterizations are applied for revealing the phase changes in leaching process. This new type of acid-free slat-leaching method provides a new idea for the recycling of spent LIBs containing metals such as nickel, cobalt, and manganese. Graphical
PubDate: 2022-05-18

• Fused Calcium Aluminate Production from Aluminum White Dross Residue

Abstract: Despite the numerous advantages of using and recycling aluminum, inevitable by-products in the form of non-metallic residues (NMR) of aluminum white dross (AWD) can be environmentally harmful. The aim of this study was to find a solution regarding aluminum treatment via pyrometallurgical methods and, ultimately, to obtain calcium aluminate (CA) flux for the iron and steel industries. The optimum parameters, such as temperature, duration, and particle size of the limestone, for CA production from the NMR of AWD were investigated. Calcination experiments were divided into two categories. The aim of the first set of experiments was to increase alumina (Al2O3) purity and remove nitrogen (N) in the rotary furnace. N content was reduced to 0.25 wt% at 1150 °C and 2 h duration, while Al2O3 purity reached 94.67 wt% as the optimum results for the calcination experiments. The obtained results were also compatible with thermodynamic simulations. In the second set of experiments, NMR of AWD was synthesized via the addition of limestone to obtain CA. It was observed that the crushed limestone favors the forming of CA phases. Last, in order to determine the optimum fusing condition, the fusion process was applied 1350, 1450, and 1550 °C to mixture of limestone and NMR. It was observed that the material completely melted at 1550 °C and phases containing CA were formed. The produced samples were characterized by X-ray diffraction (XRD), atomic absorption spectroscopy (AAS), and N analyzer. Graphical
PubDate: 2022-05-17

• Simulation of Simultaneous Leaching of Copper and Cobalt Minerals in
Acid-Reductive Media: Sensitivity Analysis and Optimization

Abstract: In this study, an ASPEN Plus model in steady state, based on experimental studies, was developed to investigate the leaching behavior of copper and cobalt minerals in sulfuric acid-sodium metabisulfite media. The experimental results indicated that copper and cobalt dissolution efficiencies reach 91 and 72%, respectively. The integration of experimental parameters set-up in the ASPEN Plus simulator allowed the reliability of the developed model. The sensitivity analysis performed highlighted the relative effect of acid concentration, leaching time, temperature, and sodium metabisulfite on the leaching process. Moreover, it revealed that the dissolution of copper minerals was mainly enhanced by the increasing sulfuric acid mass flow rate. The dissolution of cobalt from asbolane was promoted by increasing sulfuric acid mass flow rate, while the extraction of cobalt contained in heterogenite highly depended on sodium metabisulfite (Na2S2O5) mass flow rate. However, a marginal decrease in copper recovery was observed by increasing the mass flow rate of sodium metabisulfite. ASPEN Plus simulated results showed that the leaching recovery could reach 99.77% and 97.92% for copper and cobalt under optimized operating conditions, respectively. Graphical
PubDate: 2022-05-16

• Correction to: Analysis of the Theoretical and Practical Energy
Requirements to Produce Iron and Steel, with Summary Equations that Can Be
Applied in Developing Future Energy Scenarios

PubDate: 2022-05-13

• Circular Economy Applied to Metallurgical Waste: Use of Slags and Fly Ash
from the Ferronickel Industry in the Production of Eco-Friendly Composites

Abstract: The aim of this paper is studying the use of industrial, solid waste materials from the ferronickel industry (fly ash—FA, electric furnace slag—EFS and converter slag—CS) as a reinforcing component in new value-added polymer-based composite: eco-friendly, functional geo-membranes. The studied geo-membranes were produced by film-casting method using polyvinyl chloride (PVC) matrix reinforced by the previously mentioned metallurgical waste materials, as-obtained and modified in acid (HCl) and alkaline (NaOH) medium. The study of the produced systems was done through observation and analysis of the effect on their: (i) morphology and internal structure (SEM and FTIR analysis), (ii) thermal stability (TG/DTA/DTG analysis) and (iii) moisture stability (the swelling kinetics was followed and the ultimate rate of swelling after 24 h was determined). The morphology of the waste materials is of spherical and polygonal non-regular shape. The morphology and microstructural properties of the obtained FA/PVC composites confirmed region of well dispersed particles where the particles were tightly embedded and mechanically interlocked in the PVC matrix indicating strong interfacial interaction with the polymer matrix. All waste materials were thermally stable with minimal 0.8% weight loss, EFS has been shown as the most stable with weight loss of 0.1% near 350 °C. Generally, all the studied composites have shown a higher swelling degree in comparison with PVC, where the composites reinforced with FA have shown the best performances in adsorption test. Graphical
PubDate: 2022-05-13

• Comprehensive Utilization of Al-Goethite-Containing Red Mud Treated
Through Low-Temperature Sodium Salt-Assisted Roasting–Water Leaching

Abstract: A combined low-temperature sodium salt-assisted roasting and water leaching process was investigated as a cleaning method for the treatment of Al-goethite-containing red mud (AGRM), which is conducive to aluminum recycling and iron mineral enrichment in leaching residue. In this work, the mineralogical characteristics and phase transformation of AGRM roasted at low temperature were evaluated by using an advanced mineral identification and characterization system, thermogravimetric analysis and differential scanning calorimetry, X-ray diffractometry, and backscatter scanning electron microscopy/energy dispersive spectrometry. In addition, the main factors, such as roasting temperature, sodium hydroxide dosage, leaching temperature, and time were investigated. Results revealed that the fraction of aluminum in Al-goethite is up to 73.59% of the total aluminum content in AGRM. The transformation of Al-goethite into Al-hematite occurred at approximately 360 °C, and adding sodium hydroxide can promote the conversion due to the formation of sodium aluminate. Compared with AGRM after roasting at 400 °C for 30 min followed by water leaching at 30 °C for 10 min, the leaching rate of aluminum increased from 0.36 to 90.21% and the grade of TFe in the leaching residue increased from 45.63 to 54.09 wt% after roasting with 25 wt% sodium hydroxide under the same conditions. Given that the enhanced transformation of Al-goethite significantly improved aluminum recovery and the obtained iron-rich leaching residue can be easily co-disposed in the steel industry, thus may achieve the almost zero-waste discharge of AGRM from the Bayer process. Graphical
PubDate: 2022-05-13

• Optimization of Gas–Steam–Electricity Network of Typical Iron
and Steel Enterprise

Abstract: Due to the fact that by-product gases constitute significant secondary energy sources in iron and steel enterprises, their reasonable distribution is critical for energy conservation and consumption reduction. In the current study, there is a lack of in-depth thinking about the impact on an entire system owing to the adjustment of single equipment in the process. In this paper, the model combined of gas distribution, steam, and electricity optimization is established based on the mechanism. By using a typical enterprise scene of adjusting the by-product gas combustion ratio of heating furnace, the impact of changes in surplus gas on the Gas–Steam–Electricity network is analyzed. When the ratio of coke-oven gas:blast furnace gas:basic oxygen furnace gas is 2:2:1, the lowest operating cost of the entire system is 95.511 CNY/t-cs, and thus, 5.2619 million CNY can be saved every year. Therefore, the rational allocation and use of by-product gas can bring considerable benefits to the whole enterprise. Graphical
PubDate: 2022-05-10

• Wettable TiB2 Cathode for Aluminum Electrolysis: A Review

Abstract: Titanium diboride (TiB2) is considered a promising material for wettable cathodes in aluminum electrolysis. The demand for wettable cathodes is associated with the development of inert anode technologies to eliminate CO2 emissions caused by the conventional aluminum reduction process. Titanium diboride has been given special attention due to its superior properties, such as high wettability, good electrical conductivity, wear resistance, and excellent chemical stability. In this paper, we discuss different synthesis techniques used for the preparation of TiB2 cathode material. The main methods are sintering, electrodeposition, and plasma spraying. Electrodeposition is considered to be the most reliable low-cost method for TiB2 preparation. The vertical anode–cathode distance can be reduced by introducing wetted TiB2 cathodes, through which specific energy consumption can be reduced significantly. For a longer lifetime, the TiB2 cathodes should be resistant to electrolyte penetration. Further research should be conducted to understand the electrochemical behavior of TiB2 in low-temperature electrolytes. Graphical
PubDate: 2022-05-02

• Hydrochlorination of Copper-Cobalt Alloy for Efficient Separation of
Valuable Metals

Abstract: Global demand for cobalt is proliferating owing to the transition towards a low carbon economy. Recovery of cobalt from copper-cobalt alloy ensures the sustainability of the cobalt resources as it contains significant amounts of cobalt. This paper proposes a method for hydrochlorination roasting of copper-cobalt alloy with HCl gas followed by water leaching. The influences of the main factors (roasting temperature, roasting time, HCl gas flow rate, and leaching time) on the separation efficiency of the process were investigated. During the hydrochlorination roasting process, the dense structure of copper-cobalt alloy was destroyed, the Si, Cu, Fe, and Co volatilization efficiencies of 72.73%, 8.47%, 0.44%, and 0.07% were obtained. In addition, the Co, Fe, Cu, and Si in the copper-cobalt alloy were mostly transformed into CoCl2, FeCl2, Cu, and SiCl4. This is exceptionally conducive to the subsequent selective water leaching of Co and Fe and reduces the difficulty of subsequent purification. It was also confirmed by the leaching experiments. For the leaching process, Co and Fe were selectively extracted from roasted product, and Cu retained in the residue mainly in the form of metallic copper. The water leaching efficiencies of Co, Fe, and Cu in the roasted product were 87.76%, 93.25%, and 4.85% under optimized conditions. Graphical
PubDate: 2022-04-26

• Hydrometallurgical Recovery of Manganese from Ferruginous Manganese Ore by
Reductive-Acid Leaching with Sodium Dithionite

Abstract: The leaching behavior of manganese from ferruginous manganese ore in sulphuric acid solution using sodium dithionite as a reducing agent was investigated. The optimum sulphuric acid concentration, leaching time, temperature, pulp density and agitation speed for leaching of manganese was determined. Complete manganese leaching was observed under the optimized conditions of 0.6 M H2SO4, 0.49 M sodium dithionite, 200 g/L pulp density, 60 °C leaching temperature, 600 rpm stirring rate and 120 min reaction time. The leaching kinetics and dissolution process have also been analyzed by model fitting and microstructural observation. The kinetics of reductive leaching of manganese ores by sodium dithionite in dilute sulphuric acid did not follow a shrinking core kinetic model. The Avrami model was used successfully to explain the kinetic data. The positive values of both ∆H and ∆S indicates that the leaching process is endothermic and random while the negative values of ∆G indicate that manganese dissolution process is spontaneous in nature. After removal of impurities from the leach solution by precipitation, a high purity (99.2%) α-Mn2O3 was synthesized from the concentrated Mn solution. The as-synthesized manganese oxide powder was characterized by chemical analysis, SEM–EDS and XRD analysis. The present process would be a key technology for reductive leaching of manganese oxide ores in an economical and efficient way. Graphical
PubDate: 2022-04-25

• Kinetic Study on Volatilization of the SnO–SiO2 and
SnO–SiO2–CaO Systems

Abstract: The high-temperature volatilization behavior of the SnO–SiO2 and SnO–CaO–SiO2 slag systems was studied by simultaneous thermal analysis. The volatilization characteristics of the two systems with different SnO contents and different heating rates were discussed, and the kinetic parameters, reaction mechanism, and thermodynamic parameters of the volatilization reaction of the slag system at high temperature were calculated. The results of thermal analysis show that the volatilization of tin slag at high temperature is related to the activity of SnO and the decomposition of stannous silicate in tin slag. The slag system has obvious volatilization effect when the content of SnO is more than 60% in the SnO–SiO2 binary slag system. When CaO is added into the binary slag system, the volatilization of slag system becomes easier. The volatilization rate decreases with increasing heating rate. The volatilization kinetic parameters and mechanism functions of the SnO–SiO2 and SnO–CaO–SiO2 systems were calculated by Coats–Redfern and Achar–Brindley–Sharp–Wendworth methods. It is concluded that the volatilization of tin slag at high temperature is controlled by three-dimensional diffusion mechanism. The mechanism function is Jander equation with integral form of [1 − (1 − α)1/3]2 and the differential form of 3/2(1 − α)2/3[1 − (1 − α)1/3]−1. The rate constants of the SnO–SiO2 and SnO–CaO–SiO2 systems are $$k\, = \,1.36\, \times \,10^{16} \,\exp \,\left( {{{ - \,61408.61} \mathord{\left/ {\vphantom {{ - \,61408.61} T}} \right. \kern-0em} T}} \right)$$ and $$k\, = \,1.61\, \times \,10^{17} \,\exp \,\left( {{{ - \,64869.66} \mathord{\left/ {\vphantom {{ - \,64869.66} T}} \right. \kern-0em} T}} \right)$$ , and the isokinetic temperatures are 1174.4 and 1208.3 °C, respectively. Finally, the thermodynamic parameters of the slag system in the high-temperature volatilization process are discussed. The activation enthalpy ΔH of the SnO–SiO2 and SnO–CaO–SiO2 systems is 498.33 and 526.96 kJ/mol, respectively. The activation Gibbs free energy ΔG is 436.56 and 433.87 kJ/mol, and the activation entropy ΔS is 42.66 and 62.84 J/(mol K), respectively. Graphical
PubDate: 2022-04-25

• Rheological Properties and Structures of CaO–Al2O3–La2O3–B2O3 Slags
with Various B2O3 Contents

Abstract: Aiming at the problem of severe steel-flux reaction and fluorine pollution occurred in the process of continuous casting La-bearing FeCrAl alloy with conventional CaO–SiO2–Na2O–CaF2-based mold fluxes, the low-reactive and environmentally friendly CaO–Al2O3–La2O3–B2O3 slag system was designed, and rheological behavior of the slags with different B2O3 contents was studied. Results showed that with the increase of B2O3 from 0 to 15 wt%, the slag viscosity and activation energy decreased gradually. Structural analysis indicated that B3+ mainly existed in the form of planar [BO3]-triangular structure with the addition of B2O3. With increasing B2O3 contents, [BO3] units entered into the initial aluminate network structure via destroying AlIV–O–AlIV linkages to form more AlIV–O–BIII and B–O–B linkages, resulting in the increase of bridging oxygen and the polymerization of slag structure. Due to the layered structure of [BO3] units, the molecular attraction of B–O bonds between the layers was weak, which reduced the overall slag structural strength, thus, leading to the decrease of viscosity. The break temperature decreased gradually on the whole with the addition of B2O3. The precipitated amount of CaAl2O4 reduced with increasing B2O3 content, which resulted from the decrease of high-polymerized [AlO4]-tetrahedral structure. In this study, Ca2+ played the charge compensation effect owning to its small cationic field strength, while La3+ mainly interacted with NBOs for balancing charges. Graphical
PubDate: 2022-04-25

• Characterization and In Situ Abatement of SOx, NOx, and PCDD/Fs in Iron
Ore Sinter Machine Wind Legs

Abstract: It was observed that the oxides of sulfur and nitrogen (SOx and NOx), in large concentrations, were getting released from certain wind boxes of the sinter machine. The deposits in the wind legs were characterized and particulates with spherical, cubical, needle, and bar-like morphologies containing K, Na, and Cl were noticed. Nitrogen-based solids were found in clutter-like morphology. Some particles had a mixture of the above, SOx and NOx. These deposits were dissolved at room temperature in the solutions of sodium bicarbonate, urea, and di-sodium borate deca-hydrate (borax) in water to estimate the absorbance of K, Na, Cl, Ca, Mg, S, and N-based compounds. The solution of sodium bicarbonate did not capture NOx. SOx and NOx were not present in the filtrates of urea and borax. A solution of sodium bicarbonate in water 1% v/v was sprayed into a wind box and found that SOx had got reduced by 90% and NOx by about 55%. To maximize the capture of SOx and NOx, the solution was optimized at 2% v/v and found that both SOx and NOx had got reduced by 90%. A deposit from the electrostatic precipitator (ESP) was dissolved in acetone, hexane, and toluene and found that polychlorinated dibenzo para-dioxins and polychlorinated dibenzofurans (PCDD/Fs) have got broken down. Injecting nitrogen where PCDD/Fs are released is also suggested as an economical solution. Graphical
PubDate: 2022-04-20

• Kinetic Investigation of Initial Oxidative Dissolution of Pyrite in
Alkaline Media (pH 9–12) and Influence of Ca and Mg: A Fundamental Study
for Pyrite Depression in Froth Flotation

Abstract: Froth flotation is a common mineral processing technique that is used to remove low economic gangue minerals, such as pyrite, from ore. The main hydrophilization mechanism on the pyrite surface is explained by the formation of hydrophilic iron (Fe) hydroxide and its complexation with calcium (Ca) and magnesium (Mg) ions; however, few quantitative results are available to determine the best physico-chemical condition to depress pyrite floatability. Fe-hydroxide formation, i.e., oxidative dissolution on a pyrite surface, is a kinetically control reaction; thus, this study investigated the short-term pyrite oxidation rate (~ 360 min) and the influence of the copresence of Ca and Mg under alkaline pH conditions (9, 10.5, and 12) as a fundamental study to establish optimal flotation and/or pre-treatment conditions for pyrite depression. The oxidative dissolution rates of pyrite increased after 120–150 min of reaction compared with the first reaction time: the rate constant (log k) increased from − 10.08 to − 9.5 in the absence of Ca and Mg. X-ray photoelectron spectroscopy analysis results showed that the formation of Fe1−xS2 became the dominant reaction in the first reaction stage; thereafter, S–S bond cleavage in the second reaction stage resulted in the acceleration of pyrite decomposition. Smaller rate constants resulted for the Ca and Mg solutions because of the formation of Ca and Mg hydroxides under alkaline conditions. However, this decrease in oxidation rate could influence the pyrite surface hydrophilization less, and hydrophilization has become the main reason for pyrite depression enhancement. Graphical
PubDate: 2022-04-19

• Recovery of Some Rare-Earth Elements by Sorption Technique onto Graphene
Oxide

Abstract: In this work, graphene oxide (GO), prepared using the Hummers method, is physically characterized and used for rare-earth metals recovery from monazite ores. Batch study for sorption of 152+154Eu radionuclide onto GO carried out to assess the optimum reaction parameters for recovery process. The optimum pH is 2.09, the equilibrium time achieved after 5 h, humic acid enhances the sorption efficiency but if its concentration increases it opposes the sorption process. The kinetic reaction mechanism is regulated by pseudo-2nd order and the sorption isotherms show Langmuir applicability. The maximum sorption capacity for 152+154Eu at 20 °C is 59.81 mg g−1. Desorption studies were performed to determine a proper eluent with a suitable concentration for the recovery process and 0.1 M HCl was selected as an efficient eluent. The sorption process is favorable and endothermic. Finally, GO is used as a sorbent for rare-earth elements accumulated in monazite ore. The sorption efficiency of REE is 69.03% with initial concentration 1149.57 mg L−1 at monazite leachate and the recovery percentage is 20.32%. These results promised the use of GO for REE recovery from monazite ore. Graphical
PubDate: 2022-04-19

• Sustainable Low-Cost Method for Production of High-Entropy Alloys from
Alloy Scraps

Abstract: In this communication, we propose a sustainable way to produce high-entropy alloys (HEAs) from alloy scraps called “alloy mixing”. We successfully demonstrate the method's feasibility at a lab scale using a near-equimolar CrCuFeMnNi HEA. Alloy scraps (304L stainless steel (SS), Nichrome 80, and electrical wire grade Copper) obtained from various sources were melted together using vacuum arc melting along with minor additions of Mn and Cr to achieve the equiatomic composition. The alloy was characterized using X-ray diffraction (XRD) and scanning electron microscopy (SEM), which confirmed that the alloy produced through “alloy mixing” exhibits a microstructure similar to that of the alloy with the same composition produced through conventional melting of pure elements. Property calculation module on ThermoCalc was used to compare the yield strength of the conventional alloy and the alloy with impurities which indicated a 50% increase in yield strength. An uncertainty quantification analysis with 1000 alloy compositions with varying impurity contents indicates that the yield strength is strongly dependent on the impurity content. The cost analysis revealed that "alloy mixing" would lead to a significant reduction in fabrication costs. The results of this study are promising in the context of the commercialization of HEAs. Graphical
PubDate: 2022-04-11

• The Investigation of Removal and Occurrence State of Impurity Elements
During Crude Tin Vacuum Distillation

Abstract: The present research investigates the purification of crude tin by vacuum distillation. In this paper, the saturated vapor pressure of elements in crude tin was calculated, the activity coefficients of tin-based alloy at 1473 K were predicted by molecular interaction volume model, the separation coefficients (Pb, Bi, Sb, Zn, Cu, Fe) were calculated, and the Sn–Me (Pb, Bi, Sb, Zn) vapor–liquid equilibrium phase diagrams were established. The occurrence state of impurity elements in crude tin, vacuum distillation volatiles, and residues were detected by EPMA. The results show that the impurity element Pb in crude tin occurs in the form of small particles of Pb phase, Bi occurs in the Pb phase, As and Fe will form intermetallic compound AsFe, impurity elements Ni and Cu occur in the form of solid solution (Ni,Cu) or Ni–Cu–Fe–As, and Sb exists in the tin base. In the volatile, S, Zn, and Sn are present together in the areas close to the condenser, and As, Sn, Pb, and Sb are present in the areas far away from the condenser. Fe–As, Ni–Cu, and Ni–Fe phases exist in the residue. The equilibrium concentration and separation coefficient experiments show that when distillation time was extended to 150 min, the purity of tin in the residue increased from 91.55 to 96.18%; the impurity elements Pb, Bi, and Zn can be effectively removed; and the effective separation coefficients of As and Sb are far less than the calculated values. Graphical
PubDate: 2022-04-05

• Metal Recovery from Spent LiMn2O4 Cathode Material Based on Sulfating
Roasting with NaHSO4·H2O and Water Leaching

Abstract: The reuse of waste materials helps to alleviate the pressure on sustainable economic development caused by the rapid consumption of natural resources. In this paper, a new process for the recovery of Li and Mn from spent LiMn2O4 cathode materials was studied. LiMn2O4 was mixed with NaHSO4·H2O according to a certain mass ratio and roasted, and then the roasted products were leached with deionized water. The chemical changes during roasting were studied by thermogravimetric analysis, differential scanning calorimetry, X-ray diffraction, X-ray photoelectron spectroscopy, and scanning electron microscopy. After roasting, Li exists in the form of LiNaSO4, while the form of Mn is affected by the content of NaHSO4·H2O in the mixture. Within the corresponding temperature range, the chemical reaction between LiMn2O4 and NaHSO4·H2O can proceed spontaneously. During the reaction, the following reactions will occur in the II and IV stages: NaHSO4⋅H2O → NaHSO4 + H2O(g), Na2S2O7 → Na2SO4 + SO3(g) and reaction of different metal oxides with SO3, and their average activation energies are 153.07 kJ/mol and 533.81 kJ/mol, respectively, and the restrictive link is three-dimensional diffusion. The roasted products were leached with deionized water, the extraction rate of Li and Mn elements increases with the decrease of mixing mass ratio, when the mass ratio of LiMn2O4 to NaHSO4·H2O is 1:1.07, the roasting temperature is 873 K, the roasting time is 0.5 h, under the condition of water leaching temperature of 333 K, the extraction rates of Li and Mn were 96.6% and 9.7%, respectively. Graphical
PubDate: 2022-03-28

• Thiourea Leaching: An Update on a Sustainable Approach for Gold Recovery
from E-waste

Abstract: Electronic waste is a dominant global issue with over 50 million tons generated annually. Still, as an amalgamation of precious and rare raw materials, electronic waste is a considerable economic resource with the most valuable components located on the printed circuit boards. Gold is widely used in electronics in numerous applications, although principally for contact points and external connectors. The recovery of gold, due to its high value, is one of the main motivations for recycling e-waste. Although pyrometallurgy and hydrometallurgy processing are still the preferred modes of recovery for gold, the use of high-energy consuming pyro-methods, and the use of gold cyanidation that uses harmful lixiviants are increasingly discouraged. Thiourea has received attention as an alternative lixiviant for gold leaching due to its fast reaction kinetics and less harmful nature. This review aims to provide an up-to-date evaluation of thiourea-gold leaching studies from electronic waste, with emphasis on the recent progression from the classic chemical method to a more sustainable hybrid bioleaching-based system, while its challenges are highlighted. The complementary methods applied for gold retrieval from the pregnant solution are also described with a focus on sustainable methods that have the potential to provide a closed-loop system, the key objective for material recovery in a circular economy. Graphical
PubDate: 2022-03-18

• Development and Characterization of Blue-Colored Mg2Si-Based Recycled
Alloys Using Scrap Light Metals

Abstract: Currently, major issues in the mobile and information and communications technology industries are consumer demands stimulated by emotion and environmental pollution issues. In the case of such consumer demand, many companies are using a demand increase model that involves the application of success stories through the convergence of design and technology, and a significant improvement has been realized. The environmental pollution caused by various dyes or resins used to realize a specific color of metal exterior materials to stimulate consumer sensibility has reached a serious level. In this study, we tried to minimize the environmental pollution that occurs due to external painting by realizing the color for the metal itself rather than through an external color coating. In addition, in the case of metal materials, the desired metal atomic ratio was similarly realized by utilizing waste scraps of the Al alloy ADC12 and the Mg alloy AZ91 that had already been used, and a study on realizing a specific color of the metal itself through recycling was conducted. Through this study, we tried to solve both environmental and consumer demand issues through recycling of metal waste materials and development of ecofriendly metal materials that do not use paint or resin. Graphical
PubDate: 2022-03-16

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