Subjects -> METALLURGY (Total: 59 journals)
Showing 1 - 10 of 10 Journals sorted alphabetically
Acta Metallurgica Slovaca     Open Access   (Followers: 2)
Advanced Device Materials     Open Access   (Followers: 6)
American Journal of Fluid Dynamics     Open Access   (Followers: 44)
Archives of Metallurgy and Materials     Open Access   (Followers: 9)
Asian Journal of Materials Science     Open Access   (Followers: 4)
Canadian Metallurgical Quarterly     Hybrid Journal   (Followers: 21)
Complex Metals     Open Access   (Followers: 2)
Energy Materials : Materials Science and Engineering for Energy Systems     Hybrid Journal   (Followers: 24)
Graphene and 2D Materials     Open Access   (Followers: 6)
Handbook of Ferromagnetic Materials     Full-text available via subscription   (Followers: 1)
Handbook of Magnetic Materials     Full-text available via subscription   (Followers: 2)
High Temperature Materials and Processes     Open Access   (Followers: 6)
Indian Journal of Engineering and Materials Sciences (IJEMS)     Open Access   (Followers: 11)
International Journal of Metallurgy and Alloys     Full-text available via subscription   (Followers: 2)
International Journal of Metals     Open Access   (Followers: 7)
International Journal of Minerals, Metallurgy, and Materials     Hybrid Journal   (Followers: 12)
International Journal of Mining and Geo-Engineering     Open Access   (Followers: 4)
Ironmaking & Steelmaking     Hybrid Journal   (Followers: 5)
ISIJ International - Iron and Steel Institute of Japan     Full-text available via subscription   (Followers: 26)
Izvestiya Vuzov. Poroshkovaya Metallurgiya i Funktsional’nye Pokrytiya (Proceedings of Higher Schools. Powder Metallurgy аnd Functional Coatings)     Full-text available via subscription   (Followers: 2)
JOM Journal of the Minerals, Metals and Materials Society     Hybrid Journal   (Followers: 35)
Journal of Advanced Joining Processes     Open Access  
Journal of Central South University     Hybrid Journal   (Followers: 1)
Journal of Cluster Science     Hybrid Journal  
Journal of Heavy Metal Toxicity and Diseases     Open Access  
Journal of Iron and Steel Research International     Hybrid Journal   (Followers: 11)
Journal of Materials & Metallurgical Engineering     Full-text available via subscription   (Followers: 2)
Journal of Materials Processing Technology     Hybrid Journal   (Followers: 21)
Journal of Metallurgical Engineering     Open Access   (Followers: 4)
Journal of Sustainable Metallurgy     Hybrid Journal   (Followers: 3)
Materials Science and Metallurgy Engineering     Open Access   (Followers: 7)
Metal Finishing     Full-text available via subscription   (Followers: 20)
Metallurgical and Materials Engineering     Open Access   (Followers: 7)
Metallurgical and Materials Transactions A     Hybrid Journal   (Followers: 42)
Metallurgical and Materials Transactions B     Hybrid Journal   (Followers: 32)
Metallurgical and Materials Transactions E     Full-text available via subscription   (Followers: 2)
Metallurgical Research & Technology     Full-text available via subscription  
Metallurgical Research and Technology     Full-text available via subscription   (Followers: 8)
Metallurgy and Foundry Engineering     Open Access   (Followers: 3)
Mining, Metallurgy & Exploration     Hybrid Journal  
Powder Diffraction     Full-text available via subscription   (Followers: 1)
Powder Metallurgy     Hybrid Journal   (Followers: 35)
Powder Metallurgy and Metal Ceramics     Hybrid Journal   (Followers: 7)
Powder Metallurgy Progress     Open Access   (Followers: 5)
Practical Metallography     Full-text available via subscription   (Followers: 6)
Rare Metals     Hybrid Journal   (Followers: 3)
Revista de Metalurgia     Open Access  
Revista del Instituto de Investigación de la Facultad de Ingeniería Geológica, Minera, Metalurgica y Geográfica     Open Access  
Revista Remetallica     Open Access   (Followers: 1)
Russian Metallurgy (Metally)     Full-text available via subscription   (Followers: 4)
Science and Technology of Welding and Joining     Hybrid Journal   (Followers: 8)
Soldering & Surface Mount Technology     Hybrid Journal   (Followers: 2)
Steel Times lnternational     Partially Free   (Followers: 19)
Transactions of the IMF     Hybrid Journal   (Followers: 14)
Transactions of the Indian Institute of Metals     Hybrid Journal   (Followers: 5)
Tungsten     Hybrid Journal  
Universal Journal of Materials Science     Open Access   (Followers: 3)
Welding in the World     Hybrid Journal   (Followers: 8)
Welding International     Hybrid Journal   (Followers: 11)
Вісник Приазовського Державного Технічного Університету. Серія: Технічні науки     Open Access  
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Journal of Sustainable Metallurgy
Number of Followers: 3  
  Hybrid Journal Hybrid journal (It can contain Open Access articles)
ISSN (Print) 2199-3823 - ISSN (Online) 2199-3831
Published by Springer-Verlag Homepage  [2656 journals]
  • Extraction of Nickel from Magnesia–Nickel Silicate Ore
    • Abstract: In this study, magnesia–nickel silicate ore was investigated, which contained 0.83% Ni and antigorite, chlorite, magnetite (Fe3O4), quartz, and mica as the main minerals. Chloride roasting and magnetic separation were used to treat the ore. The addition of red mud enhanced the transformation of nickel silicate to a strongly magnetic mineral mainly comprising metallic Ni and that of hematite to Fe3O4 and metallic Fe. Test results showed that a Ni concentrate with a Ni content of 11.41% and Ni recovery of 92.77% was achieved under the following optimal conditions: roasting temperature: 1373.15 K; roasting time: 120 min; CaCl2 dosage: 20%; coke dosage: 14%; red mud dosage: 30%; magnetic field intensity = 0.14 T; and grinding fineness: 90% < 0.05 mm. The major minerals in the Ni concentrate were Fe3O4, metallic Fe, and metallic Ni. Sc entered the magnetic separation tailings, creating a favorable condition for the further extraction of Sc by hydrometallurgy. The thermodynamic calculation results are in good agreement with the test results. Graphical
      PubDate: 2021-04-29
  • Rapid Leaching of Valuable Metals from Spent Lithium-Ion Batteries with
           Microwave Irradiation Using Organic and Inorganic Acid
    • Abstract: Microwave-assisted leaching of valuable metals of cobalt (Co), lithium (Li), and manganese (Mn) from cathode powder of spent lithium-ion batteries (LIBs) was investigated. Higher leaching efficiency of Co, Li, and Mn was found using ascorbic acid than hydrochloric acid (HCl). The leaching reaction was rapid (5 min) and effective (100%) for Co, Li, and Mn using 0.5 N of ascorbic acid of solid-to-liquid ratio (S/L) of 10 g/L, at microwave power of 300 W. The efficiency decreased to 52.19%, 59.23%, and 57.98% for Co, Li, and Mn, respectively, as solid concentration increased to 40 g/L. Both pseudo-first-order and pseudo-second-order models described the reaction kinetics well. The conventional leaching using 0.5 N of ascorbic acid at 65 °C required 90 min to reach > 95% leaching efficiency for Co, Li, and Mn. Compared with conventional leaching, microwave irradiation accelerates yet enhances the leaching process of valuable metals from spent LIBs. Graphical
      PubDate: 2021-04-29
  • Modeling of Powder Production During Centrifugal Atomization
    • Abstract: Centrifugal atomizer has been widely used to produce metal powders, slag granules through dry slag granulation process. In this process, liquid is poured at the center of the spinning disc, which disintegrates to form droplets, and becomes solid granules/powders on cooling. In this study, a numerical simulation has been carried out to estimate powder size considering phase change into the model, and the obtained results are validated with experimental measurements. Different mechanisms of powder production viz., direct powder formation, ligament to powder formation, and film to powder formation have been captured at various liquid flow rates and angular disc speed. The effect of composition of the model liquid slag and its properties like viscosity, density, surface tension, etc. has been studied using this mathematical model. Further, the effect of superheat on solidification was also considered. Finally, powder size distribution has been correlated with properties of the slag, superheat of the liquid, and process variables. Graphical
      PubDate: 2021-04-28
  • Laser Ablation Inductive Coupled Plasma Mass Spectroscopy (LA-ICP-MS)
           Analysis on Lead-Acid Battery System: Development of Evaluation Method of
           Sub-ppm Metal Impurity Elements
    • Abstract: In Lead-acid batteries, there are significant efforts to enhance battery performance, mainly by reducing metal impurities that negatively affect battery performance. Currently implemented impurity analysis requires significant time and effort. Wet chemical preparation method is not only hazardous due to the extensive use of acids, but generates environmental pollutants and hazardous waste which require more costly and comprehensive disposal processes. In industry, it is desirable to reduce sample processing and analysis time to improve productivity and efficiency. Laser ablation inductively coupled plasma mass spectroscopy (LA-ICP-MS) is a technique that has the potential to overcome the above issues. In this work, we demonstrate an analysis of impurities (Cu, As, Cd, Co, Se, and Te) in lead-based samples at the ppm/sub-ppm level by the LA-ICP-MS method and verify with matrix matching an accurate quantification of the impurity concentrations of interest. The resulting data, which determines to reduce analysis time more than 50% due to simple preparation step while not as accurate concentration as traditional ICP-MS with at least two times increment of relative standard deviation, provides a reasonable level of accuracy and precision in a substantially quick, cost-effective method that is viable for a high throughput industrial setting. Graphical
      PubDate: 2021-04-28
  • Using Gold-Silver Tailings on the Elaboration of Ceramic Foams
    • Abstract: Ceramic foams were elaborated from gold-silver tailings and sodium silicates as foaming agent. The effects of the temperature and sintering time in a range of 850–880 °C and 30–45 min, respectively, were evaluated. The foams obtained were characterized determining their apparent density, porosity percentage, volumetric expansion, mean pore size, and mechanical strength. The results show that the sintering time had a greater impact on the properties of the foamed material than the sintering temperature, since it was observed that the characteristics of the studied foams as a function of time had a bigger variation. In addition, an almost direct linear trend with porosity, pore diameter, volumetric expansion, and an inverse linear trend with apparent density and mechanical strength was observed. The ceramic foams obtained in the investigation achieved commercial properties at certain conditions, showing uniform pore distribution, apparent densities lower than 1.0 ton/m3, pore size lower than 1.0 mm, and mechanical strength greater than 0.4 MPa. Regarding these features, the parameters that achieved the best characteristics of ceramic foams from gold-silver tailings were obtained at temperatures of 850 ºC and 860 ºC and sintering times from 45 and 35 min, respectively. Graphical
      PubDate: 2021-04-28
  • Recovery of Copper from Ammoniacal Leachates by Ion Flotation
    • Abstract: Sulfidic copper–lead–zinc tailings can pose a significant environmental threat, ranging from generation of acid mine drainage (AMD) to dam failures. On the other hand, they can also be considered as low-grade ore resources for zinc and copper provided that novel economically feasible metal extraction and metal recovery techniques are developed. Due to the low metal concentrations in these resources, the leaching will generate dilute leachates from which metal recovery is a challenge. Ion flotation is a foam separation technique capable of recovering metal ions from dilute aqueous leachates. In this paper, ion flotation was applied to separate copper from ammoniacal leachates of microwave-roasted sulfidic tailings samples. The sulfidic tailings were first roasted at 550 °C for 60 min, for the oxidation of sulfide minerals to more easily soluble sulfates using microwave-assisted irradiation as heating source. The microwave-roasted material was then leached with a mixture of ammonia and ammonium carbonate solutions. The optimum leaching efficiencies of zinc (86%) and copper (75%) were obtained under the following conditions: liquid-to-solid ratio = 10 mL g−1, T = 90 °C, [NH3 + NH4+] = 4 mol L−1, NH3:NH4+ = 2:1, t = 5 h. From the generated pregnant leach solution, it was possible to selectively separate 85% of copper to the foam phase by ion flotation, with sodium dodecyl sulfate (SDS) surfactant, as colloidal copper(II) tetraamine dodecyl sulfate under the optimized conditions: [SDS]total = 5.85 mmol L−1, [EtOH] = 0.5 % (v/v), ttotal = 5 h, flotation stages = 3. The zinc that remained in the solution after ion flotation was recovered by precipitation (95%) as basic zinc carbonate. Graphical Copper and zinc extraction by ammoniacal leaching from microwave-roasted Cu-Zn-Pb sulfidic tailings followed by recovery of copper and zinc by ion flotation and precipitation.
      PubDate: 2021-04-27
  • Fundamental Study on the Re-utilization of Waste Magnesia-Carbon Bricks as
           MgO Additive for Iron Ore Sintering
    • Abstract: Waste magnesia-carbon bricks (MCB) exhibit great potential for being reutilized as MgO additive for iron ore sintering due to their main composition of high activity magnesia and extra carbon content. In this paper, the combustion characteristics of the carbon component of waste MCB were first studied by thermogravimetric, derivative thermogravimetric and differential scanning calorimetry thermal analysis. The influence of waste MCB utilization as MgO additive on the mineralization of sinter raw materials was also systematically investigated. The main conclusions are shown as below: (1) Compared with anthracite, the carbon component of waste MCB has relatively worse flammability and combustibility, and its combustion heat per unit mass is less; (2) As the MgO content of sinter increases from 2.0 to 3.0 wt%, the advantage of using waste MCB, compared with dolomite, as MgO additive in the crystallinity degree of sinter gradually appears; (3) At the MgO content of 3.0 wt%, the sinter using the combination of waste MCB and dolomite as MgO additive has higher content of calcium ferrite, and the distributions of main mineral compositions and pores are more uniform than the sinter totally using dolomite or waste MCB as MgO additive. Graphical
      PubDate: 2021-04-23
  • Influence of Glass Structure on the Dissolution Behavior of Fe from Glassy
           Slag of CaO–SiO 2 –FeOx System
    • Abstract: Glassy slag of CaO–SiO2–FeOx systems is an important mineral phase of steelmaking slag when being used as a fertilizer for paddy fields, because this glassy phase can easily dissolve Fe and can stabilize hydrogen sulfide and suppresses over reduction. Structural analysis using Raman spectroscopy and 29Si NMR was performed to clarify the mechanism of dissolution of the glassy slag of CaO–SiO2–FeOx systems in aqueous solutions, similar to the soil conditions of a paddy field. These results were then compared to the leaching results reported previously. The structural unit of SiO4 tetrahedra in the glassy oxide showed a decrease in the fraction of Q2 and Q3 and an increase in the fraction of Q0 and Q1 with increasing basicity and FeO content. Both the Raman and NMR spectra showed a significant decrease in Q0 and Q1 peaks after leaching, indicating that the Q0 and Q1 in the glassy slag were selectively dissolved. A comparison between the average number of bridging oxygens measured by Raman spectroscopy and the amount calculated by composition showed that a deviation occurs and increases when the basicity and FeO content are high. Based on this, it was assumed that some FeO started to bond to bridging oxygens. Graphical
      PubDate: 2021-04-23
  • Equilibrium Distributions of Pb, Bi, and Ag between Fayalite Slag and
           Copper-Rich Metal, Calcium Ferrite Slag and Copper-Rich Metal.
           Thermodynamic Assessment and Experimental Study at 1250 °C
    • Abstract: Rising concentrations of impurities are expected at copper fire-refining stage due to lower availability of high-quality copper concentrates and due to increasing recycling of electronics and other secondary materials in primary copper smelting. Extra steps involving the removal of impurities from copper into the slag phase may provide a solution, but better understanding of thermochemistry is needed to evaluate the feasibility of changes in the process. In the present study, the distribution coefficients of Pb, Bi, and Ag between the fayalite or calcium ferrite slags and copper-based metal at 1250 °C were measured experimentally, using high-temperature equilibration, rapid quenching, and electron probe X-ray microanalysis (EPMA). The experiments were undertaken in a closed system using a modified substrate support technique, at relatively high oxidizing conditions typical for copper refining. The improved substrate technique enables the measurement of distributions coefficients for slags in equilibrium with solid spinel (Fe3O4) or dicalcium ferrite (Ca2Fe2O5). Experimental results of the present study and the literature data were analyzed together using thermodynamic modeling. As a result, thermodynamic database has been developed and used to predict the effects of oxygen partial pressure, wt% Cu in slag, temperature, and Fe/SiO2 and Fe/CaO in slags on the distribution coefficients of Pb, Bi, and Ag for the fayalite and calcium ferrite slag systems. Graphical
      PubDate: 2021-04-19
  • Effects of (CaO + BaO)/Al 2 O 3 Ratio on the Melting, Crystallization,
           and Melt Structure of CaO–Al 2 O 3 -10 wt% SiO 2 -Based Mold Fluxes for
           Advanced High-Strength Steels
    • Abstract: Advanced high-strength steels (AHSSs) have been applied to the automobile industry due to the advantages of low energy consumption and high safety. The non-reactive CaO–Al2O3-based mold fluxes with low/no SiO2 content have been proposed for developing the efficient casting technology of sustainable AHSSs, due to the occurrence of the reaction between AHSSs and conventional CaO–SiO2-based mold flux. Then, the effects of (CaO + BaO)/Al2O3 ratio on the melting, crystallization, and melt structure of a designed non-reactive CaO–Al2O3-10 wt% SiO2-based mold flux system have been studied. Results suggested that a higher (CaO + BaO)/Al2O3 ratio would lower the melting temperatures of the mold fluxes, and the slag system showed a good thermal stability during the melting process with the evaporation less than 5.10%. Besides, the crystallization behavior was promoted with the increase of (CaO + BaO)/Al2O3 ratio, which is associated with the reduction of the polymerization degree of the melt structure, because of the high polymerization degree of Q2(Si) structural units, and the symmetric and asymmetric [AlO4]5−-tetrahedral structures were destroyed by the released O2− ions. Thus, the migration resistance of ions and atom groups was reduced, and then the growth kinetics of LiAlO2 and Ca2SiO4 crystals were improved. When 7.42 wt% BaO was added to Sample D with (CaO + BaO)/Al2O3 ratio at 1.75, the crystallization was promoted with the decomposition of melt structure, and the Ba-bearing phase of Ba3Al2O6 crystal was precipitated to replace the main crystalline phase of LiAlO2 due to the tight junction of Ba2+ and [AlO4]5− for compensating the Al3+ charge. Graphical
      PubDate: 2021-04-15
  • Study of the Hydration Behavior of Synthetic Ferropericlase with Low Iron
           Oxide Concentrations to Prevent Swelling in Steel Slags
    • Abstract: Steel slags generally swell when subjected to water or humidity, which prevents proper recycling in the cement or asphalt industries. The MgO and CaO phases in steel slags are responsible for this phenomenon, as both minerals easily absorb water to form their respective hydroxides. MgO is often present in steel slags in a solid solution with several oxides, constituting the so-called RO phase. This study investigates the hydration rate of an RO phase consisting of FeO and MgO called ferropericlase. The material was synthesized in a laboratory furnace by sintering a FeO–MgO powder mixture with varying initial FeO contents (approximately 10, 15, and 20 wt%). Thereafter, electron probe micro-analyzer (EPMA) and X-ray diffraction (XRD) spectroscopies were used to characterize the structure of the samples, which were mainly composed of ferropericlase and an exsolution of magnesioferrite. Also, Mössbauer spectra showed that the total ferrous iron proportion (Fe2+/ΣFe) of the sintered samples was in the range of 0.55–0.72. To measure the hydration behavior, the samples in powder form were cured in an autoclave at an H2O partial pressure of 2 atm. Thereafter, thermal gravimetric analysis (TGA) was performed to measure the amount of water absorbed during the autoclave curing from the mass drop associated with the dehydration of the hydroxide. The study found a linear correlation between the initial FeO content and the weight loss after TGA, with a reduction down to 6% in the sample with an initial FeO content of 20 wt% content compared to pure MgO. Graphical
      PubDate: 2021-04-12
  • Optimization of Multistage Precipitation Processes for Rare Earth Element
           Purification from Indonesian Zircon Tailings
    • Abstract: This study investigated the effects of temperature, pH, and stirring speed of multistage precipitation processes. The purification process consists of uranium and thorium precipitation, oxalate precipitation, calcination, HNO3 leaching, and oxidation; finally, multistage precipitation is performed using Na2CO3 and NH4OH. The precipitation efficiencies of light rare earth elements (LREEs) and heavy rare earth elements (HREEs) reached 88% and 74%, respectively, during precipitation with 15% Na2CO3 at a temperature of 50 °C, pH of 4.5, and 200 rpm. The precipitation process was continued by adding 10% NH4OH to the first precipitation raffinate. A total of 45% of the LREEs were recovered at a temperature of 30 °C, pH of 8, and 300 rpm. Meanwhile, 72% of the HREEs were recovered at a temperature of 30 °C, pH of 7, and 200 rpm. It was observed that Na2CO3 was effective in precipitating rare earth elements (REEs) at higher temperatures, whereas NH4OH was better at precipitating the HREEs from an REE-nitrate solution under the same processing conditions. Graphical
      PubDate: 2021-04-09
  • Determination of the Fe 3+ / $${\varvec{\Sigma}}$$ Σ Fe Ratio in
           Synthetic Lead Silicate Slags Using X-Band CW-EPR
    • Abstract: The oxidation balance is arguably one of the most important parameters during pyrometallurgical processes. In many cases, iron is the most abundant multivalent element present in silicate slags. Within these molten oxide mixtures, the oxygen balance is dominated by the relative fractions of Fe3+ and Fe2+ present. Measuring the concentration of ferrous and ferric iron in quenched slags can provide useful information about the oxidation state of the liquid slag at the moment of freezing. These measurements are not always straightforward, especially in lead-rich slags, as present in modern secondary smelting processes. Building on previous work, this article aims towards a practical and reliable methodology for determining the Fe3+ concentration in lead-rich silicate slags using continuous wave electron paramagnetic resonance (CW-EPR). The method is demonstrated for different Fe3+/ \(\Sigma \) Fe ratios and a basic model is proposed that relates the slag composition to the EPR spectrum, optimized for a high-lead ternary PbO–SiO2–Fe2O3 slag. Graphical
      PubDate: 2021-04-08
  • Investigation of Formation and Shedding Behavior of Slag Crust in a Large
           Blast Furnace with Copper Stave: Flow Properties and Crystallization
    • Abstract: The damage of the copper stave will affect the sustainable production of the blast furnace and is not conducive to improving the economic efficiency of the blast furnace. The formation of a stable slag crust is crucial for the longevity of the copper stave. In this study, the flow properties and crystallization characteristics of the slag crust in a blast furnace with the copper stave running for 10 years without damage in China were analyzed. The phase precipitation during the cooling process was calculated by FactSage software. The phase composition and micromorphology of the slag crust were studied in detail by XRD and SEM–EDS. The results show that the slag phase in the slag crust is a CaO-SiO2-Al2O3-MgO-FeO slag system with high alumina content (33.62 ~ 35.72%) and low magnesium oxide content (2.68 ~ 3.84%). The melting characteristic temperature of the slag crust in the belly and the bosh is between 1127–1303 °C and 1287–1500 °C, respectively, and the characteristic temperature of the cold side of the slag crust is higher than that of the hot side, which was mainly resulted from the tendency of gehlenite and magnesia-aluminum spinel in the slag phase to precipitate during the cooling process. With the increase of the basicity of the slag phase, the precipitation temperature and amount of gehlenite increase, resulting in the characteristic temperature of the slag crust in the bosh significantly higher than that in the belly. The increase of FeO content reduces the initial precipitation temperature of crystals, and the increase of cooling strength is beneficial to the slagging on the copper stave, which provides a theoretical basis for the stable operation of the slag crust on copper stave blast furnace. Graphical
      PubDate: 2021-04-05
  • Recovery of Cu(II) by Acorga M5640 After Leaching of Malachite Ore in
           Perchloric Acid Solutions
    • Abstract: In the present study, the recovery of Cu2+ from the resulting actual leach solution after the leaching of malachite ore in perchloric acid solutions was examined by applying the solvent extraction method. The organic phase was prepared using Acorga M5640 and kerosene. The effects of the initial pH of solution, extractant concentration, Cu2+ concentration, temperature, and stirring speed on the extraction process were investigated. It was determined that the extraction yield increased with an increase in the extractant concentration, initial pH of aqueous solution, stirring speed, and temperature, and with a decrease in the concentration of Cu2+. To prevent or minimize Zn2+ transfer to the organic phase and to ensure maximum Cu2+ extraction from the aqueous phase, the optimal values for the initial pH of the aqueous phase, initial concentration of Cu2+, extractant concentration, temperature, and stirring speed were selected to be 1, 0.152 g/L, 4% (v/v), 25 °C, and 400 rpm, respectively. The stoichiometry and mechanism of the extraction process were determined applying the equilibrium slope method. The changes in the Gibbs free energy, enthalpy, and entropy were determined. The changes in these thermodynamic parameters were calculated to be − 3.87 kJ/mol, 64.67 kJ/mol, and 0.23 kJ/(mol K), respectively. Graphical The extraction percentage of Cu2+ increases substantially when the initial pH of the leach solution increases from 0.1 to 1. The further increase in the initial pH above 1 does not create an increase in the extraction extent of Cu2+. When the initial pH of the leach solution is higher than 1, the amount of Zn2+ transferred from the aqueous phase to the organic phase increases significantly.
      PubDate: 2021-04-02
  • Sodium Thiosulfate and Natural Sulfur: Novel Potential Additives for
           Selective Reduction of Limonitic Laterite Ore
    • Abstract: The diminution of sulfide ore deposit as the main source of nickel extraction initiates the development of alternative methods to maximize the processing of low-grade nickel ore including limonitic laterites. Aiming to produce ferronickel with high nickel content and recovery, the study used sodium thiosulfate and natural sulfur as novel additives to be employed in selective reduction techniques. The reduction process was conducted at 1400 °C for 6 h in a coal–limestone bed. Ores and the as-reduced products were characterized by Emission Dispersive X-Ray (EDX) and X-Ray Diffraction (XRD) to determine the elemental composition in the product and examine the phase transformation of ores. Results showed that utilization of 10%wt Na2S2O3 resulted in a product with 14.31% Ni content and 93.22% recovery, while the employment of 10%wt natural sulfur yielded a product with 13.62% Ni content and its recovery reaching 97.91%. Phase identification of slag product using XRD pointed out that both Na2S2O3 and natural sulfur additives assisted the transformation of ore mineralogy in which the kamacite and taenite phases of metal products confirm the successful formation of ferronickel (Fe, Ni). Furthermore, slag products showed a large amount of iron compound, confirming the fact of low iron recovery. Graphical
      PubDate: 2021-03-23
  • Leaching Kinetics of Mo, Ni, and Al Oxides from Spent Nickel–Molybdenum
           Hydrodesulfurization Catalyst in H 2 SO 4 Solution
    • Abstract: Spent Ni–Mo hydrodesulfurization catalyst (HDS) includes a considerable amount of Mo, Ni, and Al and is used as an important secondary resource for the recovery of valuable metals. The effect of grinding, stirring speed, H2SO4 concentration, and temperature on the leaching rate of spent catalyst was investigated. Leaching behavior of MoO3, NiMoO4, Al2O3, and AlPO4 from spent catalyst was determined. Leaching kinetics of MoO3, NiMoO4, Al2O3, and AlPO4 was explained by Avrami Kinetic Model. Kinetic parameters such as apparent activation energy, pre-exponential factor, order of acid concentration, and Avrami coefficient were calculated and model equations were derived. Apparent activation energy values were calculated for the leaching of MoO3, NiMoO4, Al2O3, and AlPO4 from spent catalyst in H2SO4 solutions as 22.02, 41.74, 57.80, and 42.32 kJ mol−1. Graphical
      PubDate: 2021-03-19
  • Phosphorous Recovery from Ca 2 SiO 4 –Ca 3 P 2 O 8 Solid Solution By
           Carbothermic Reduction
    • Abstract: Steelmaking slag is considered as a promising phosphorus resource as it contains the phosphorus in a condensed phase of Ca2SiO4–Ca3P2O8 solid solution (C2S–C3P)ss. In the present study, the carbothermic reduction of (C2S–40 mol% C3P)ss at 1573 K was carried out to understand the phosphorus removal mechanism by varying reduction temperature, external gas flow rate, amount of graphite, and concentration of Ca3P2O8 in (C2S–C3P)ss. The carbothermic reduction proceeded as a zero-order reaction when the temperature was 1573 K, despite the P2O5 concentration decrease with the reduction time. At temperatures less than 1473 K, the reduction did not occur. Based on the XRD analysis of the reduced (C2S–C3P)ss samples, it was found that carbothermic reduction of the C2S–C3P solid solution proceeded by the decomposition of the C2S–C3P solid solution into CaO and C2S with the removal of phosphorus, but not by a uniform decrease of the phosphorous throughout the C2S–C3P solid solution. The overall reduction degrees were found to be independent of the reduction rate (zero-order reaction) and the P2O5 concentration in the (C2S–C3P)ss. From these independencies, the rate-controlling step of the carbothermic reduction of (C2S–C3P)ss was concluded to be the Boudouard reaction. Graphical
      PubDate: 2021-03-18
  • Study of the Processing of a Recycled WC–Co Powder: Can It Compete with
           Conventional WC–Co Powders'
    • Abstract: Cemented carbide tools suffer from many issues due to the use of tungsten and cobalt as raw materials. Indeed, those are listed by the European Commission as “critical raw materials” since 2011 and by the US Department of Interior as “critical minerals” in 2018. To remain competitive with the conventional high-speed steels, less performant but cheaper, WC–Co tools can be recycled. In the present paper, a WC–7.5Co powder, recycled by the “Coldstream” process, has been sintered with vacuum sintering. As preliminary experiments have shown that the sinterability of the powder is low, the sintering temperature was set at 1500 °C to achieve full density. In parallel, the influence of ball milling conditions (rotation speed and milling medium) on the reactivity of the recycled powder has been studied in terms of grain size distribution, hardness, and fracture toughness. The optimized milling conditions were found to be 6 h wet milling, leading to a hardness of about 1870 HV30 and a toughness of about 10.5 MPa√m after densification. The recycled powder can thus totally compete with conventional powders, opening avenues for the recycling of cemented carbide tools. Graphical
      PubDate: 2021-03-17
  • Weathering Behavior of Newly Developed Highly Fluxed DRI
    • Abstract: The weathering behavior of highly fluxed and reduced iron ore pellet (DRI-Direct Reduced Iron) having 4, 6, and 8 basicity and 65–98% R (R-reduction) are given in this paper. The primary objective has been to solve weathering issues related to DRI and fresh lime used in the secondary steelmaking process. Experimental studies indicated that the addition of lime during pellet making and its subsequent reduction in coal bed yielded weather-resistant fluxed DRI with lime present in combined state. Such fluxed DRI exposed to 10 days open air (85% humidity) resulted in only 2 wt% moisture adsorption. The 30 days of air exposure caused 6 wt% moisture adsorption within acceptable limits for industrial acceptance. This low moisture adsorption by fluxed DRI was perhaps due to the presence of lime in combined form. Graphical
      PubDate: 2021-03-12
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Heriot-Watt University
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