R. Khoshhal, M. Soltanieh, M. A. Boutorabi,
Volume 13, Issue 1 (3-2016)
Abstract
Al2O3/TiC composites are used as cutting tools for machining gray cast iron and steels. The addition of iron improves the toughness of Al2O3/TiC composites. Ilmenite, aluminum and graphite can be used to produce in-situ Al2O3/TiC–Fe composites. However, the formation mechanism and reaction sequences of this system are not clear enough. Therefore, the present research is designed to determine the reactions mechanism of the first step of reactions that may be occurred between raw materials. In this research, pure ilmenite was synthesized to eliminate the effects of impurities available in the natural ilmenite in the system. The milled and pressed samples, prepared from the synthesized ilmenite, aluminum and graphite mixture with a molar ratio of 1:2:1, were heat treated at 720°C for 48h. In addition, two samples one containing ilmenite and aluminum with a molar ratio of 1:2 and ilmenite and graphite with a molar ratio of 1:1 were heat treated at 720°C for 48h. The final products were analyzed with XRD. It was found that at 720°C, aluminum reacts with FeTiO3, forming Fe, TiO2 and Al2O3. Since the aluminum content used in the mixture was more than the stoichiometry for reaction of ilmenite and aluminum, some unreacted aluminum remains. Therefore, the residual aluminum reacts with the reduced Fe to form Fe2Al5.
N. Alavifard, H. Shalchian, A. Rafsanjani-Abbasi, J. Vahdati Khaki, A. Babakhani,
Volume 13, Issue 3 (9-2016)
Abstract
In the present work, iron recovery from a low-grade hematite ore (containing less than 40% iron), which is not applicable in common methods of ironmaking, was studied. Non-coking coal was used as reducing agent. Reduction experiments were performed under various coal to hematite ratios and temperatures. Reduction degree was calculated using the gravimetric method. Reduced samples were subjected to magnetic separation followed by X-ray diffraction analysis. Total iron content, degree of metallization and recovery efficiency in magnetic part were determined by quantitative chemical analysis, which were obtained about 82%, 95% and 64% respectively under optimal conditions. CaO as an additive improved ore reducibility and separation efficiency. The microstructure of reduced samples and final products were analyzed by scanning electron microscopy. Final product with a high degree of metallization can be used in steel making furnaces and charging of blast furnaces which can improve production efficiency and decrease coke usage.
M. Monzavi, Sh. Raygan,
Volume 17, Issue 3 (9-2020)
Abstract
Low-grade iron ores contain many impurities and are difficult to upgrade to make appropriate concentrates for the blast furnace (BF) or direct reduction (DR) technologies. In this study, the beneficiation of an Oolitic-iron ore (containing 45.46wt% Fe2O3) with magnetization roasting by non-coking coal (containing 62.1wt% fixed carbon) under a stream of argon gas was investigated. Then, a 2500 Gaussian magnet was used for dry magnetic separation method. The effects of roasting time, ore particle size and reaction temperature on the amount of separated part and grade of the product were examined. It was found out that the hematite inside of ore could almost be completely converted into magnetite by stoichiometric ratio of coal to ore at the roasting temperature of 625 °C for 25 min. Under the optimum condition, a high amount of magnetic part of the product (72.22 wt%) with a grade of 92.7% was separated. The most important point in this process was prevention of reduced ore from re-oxidation reaction by controlling roasting atmosphere, time and temperature. In addition, different analytical methods such as X-ray fluorescence (XRF), X-ray diffraction (XRD), differential thermal analysis (DTA), thermogravimetric analysis (TG) and scanning electron microscopy (SEM) were applied to investigate and expound the results.
Hamed Tavakoli, Mohammad Reza Aboutalebi, Seyed Hosein Seyedein, Seyed Nezameddin Ashrafizadeh,
Volume 18, Issue 1 (3-2021)
Abstract
Separation of samarium and lutetium was investigated through solvent extraction from their mixed aqueous species using commercial extractants of D2EHPA and PC88A. The Response Surface Method (RSM) was utilized to design the solvent extraction experiments. In which, a Central Composite Design (CCD) was applied to set the optimum conditions for highest separation factors between Sm and Lu. Design of Experiments (DOE) was conducted by making use of four operating variables, namely initial pH of the aqueous solutions (A: 0.2–2.6), extractant concentration (B: 0.01-0.09 molar), mole fraction of D2EHPA in the extractant mixture (C: 0 - 0.8) and a type of acidic solution (D: sulfuric and nitric acid) at three levels. The results indicated that the initial pH was the most paramount variable in solvent extraction of samarium and lutetium, while in the case of lutetium, the molar fraction of D2EHPA in the mixed extractants was non-influential. The statistical model predictions were confirmed by experiments for both samarium and lutetium extraction with high validity parameter of 97 and 98%, respectively. The optimum conditions for samarium and lutetium separation were identified as: A=0.8, B= 0.05, C= 0.2 and D= sulfuric acid. According to the findings of the model, the desirability value at the optimum conditions was evaluated as about 0.93, in which 71% of lutetium was extracted while the amount of extracted samarium was only less than 1%.
Iman Babaei Nezhad, Hossein Aghajani, Seyed Hossein Seyedein, Mohammad Reza Aboutalebi,
Volume 21, Issue 0 (3-2024)
Abstract
The Mo-30 wt% W solid solution is a well-established molybdenum-based alloy. A recent approach to alloying Mo and W involves the simultaneous reduction of their oxides by hydrogen. Several studies have reported the production of Mo-W alloys via the reduction of mixed oxides. But the alloying mechanism and the effects of key reduction parameters on alloy formation remain uninvestigated. In the present study, the simultaneous hydrogen reduction of MoO₃–WO₃ mixed oxides was investigated as a potential route for producing pre-alloyed Mo–W powders. In this study pre-alloyed Mo-30 wt% W is. The effects of reduction temperature and holding time on phase evolution, morphology, and alloy formation were systematically examined. The chosen temperature range is 600-1050°C. The influence of time on phase formation and morphology during the hydrogen reduction of molybdenum and tungsten oxides is examined over a 30-360 minute period. Other parameters such as heating rate (20℃min
), bed height (10mm), H₂ flow rate (500mlmin
), and material weight (14.3g) were kept constant. The reduced samples are analyzed using X-ray diffraction (XRD) and scanning electron microscopy (SEM). The effects of temperature and time on the reduction processes are closely linked. Results indicate the formation of MoO₂ and WO₂ phases at 600°C after 60 minutes of hydrogen reduction. No Oxide phases were detected in XRD analysis of the sample that was reduced at 800°C for 180 minutes. Therefore, tungsten and molybdenum coexist in all particles of the samples. Mass transfer between Mo and W takes place during the reduction of oxides to the metallic phase. But isothermal reduction does not yield a homogeneous alloy. In these studies, for T > 800°C, increasing time has minimal effect on alloying these elements. At T=800°C, a significant change in morphology occurs at t>180 min. At T=800°C, a notable morphological change occurs after t>180 min. These changes are caused by the CVT mechanism. The optimal conditions for achieving chemical homogeneity in the alloy powder particles after reduction were identified as: 600°C for 60 min, 600 to 1050 for 240 min, and 180 min at 1050°C. This cycle leads to the formation of homogeneous alloy powder particles. The achieved homogeneity is attributed to providing sufficient time for mass transport between molybdenum and tungsten oxide particles through gaseous chemical species formed within this temperature range.
Daniela Grigorova, Gyunver Hodjaoglu, Feyzim Hodzhaoglu,
Volume 23, Issue 2 (6-2026)
Abstract
Producing high-purity iron powders with controlled particle morphology is essential for advanced powder metallurgy, additive manufacturing, and functional materials. However, achieving precise morphological control in environmentally benign, additive-free electrolytes remains challenging. This study systematically investigates the galvanostatic electrodeposition of iron powder from sulfate-based electrolytes containing 10.0 and 50.0 g·L⁻¹ Fe²⁺, focusing on the interplay between current density, pH evolution, deposition efficiency, and particle structure. A clear transition from compact, adherent deposits at low current densities to dendritic, easily detachable powders at higher values was observed. SEM analysis revealed well-defined dendritic aggregates at 7 A·dm⁻² (30–80 μm), whereas highly fragmented, porous agglomerates formed at 10 A·dm⁻², accompanied by fine-scale fragmentation driven by intense hydrogen evolution. XRD confirmed pure α-Fe for current densities up to 7 A·dm⁻², while partial oxidation to Fe₃O₄ occurred at 10 A·dm⁻²; EDX mapping further supported this surface oxidation. The deposited mass increased linearly with current density for both Fe²⁺ concentrations, with regression models yielding R² values above 0.96. Current efficiency decreased at high current densities due to enhanced parasitic reactions. Overall, the results demonstrate that galvanostatic electrodeposition in additive-free sulfate media enables controlled synthesis of iron powders, with tunable morphology and phase purity governed primarily by current density and electrolyte composition.
