Search Results (35)

Compared with vanadium extraction by sodium roasting followed by water leaching, the calcification roasting–sulfuric acid leaching method is considered a promising approach for the comprehensive utilization of vanadium titanomagnetite, as it avoids the introduction of alkali metals. However, during vanadium extraction by sulfuric acid heap leaching, the diffusion of leaching reagents and leaching products was hindered by the deposition of leaching solid products. To address this issue, this study systematically investigated the leaching kinetics and the mechanisms underlying the deposition of leaching solid products. The results indicated that vanadium leaching was governed by a combination of liquid film diffusion and internal diffusion through solid-phase products during days 0–2, and by internal diffusion alone from day 2 to day 9. The primary solid products formed during leaching were calcium sulfate and silica gel. Calcium sulfate precipitated and grew within the pore via two-dimensional nucleation, while silicates formed silica gel through dehydration. By optimizing the sulfuric acid leaching conditions—specifically, maintaining an H⁺ concentration of 2 mol/L, a leaching temperature of 40 °C, and a liquid-to-solid ratio of 5:1—the formation of calcium sulfate and silica gel was effectively suppressed. Under these conditions, the vanadium leaching efficiency reached 75.82%. Full article

Hydrogen-based reduction followed by the electric furnace smelting of vanadium–titanium magnetite pellets offers notable advantages, including high reduction efficiency, reduced energy consumption, lower CO₂ emissions, and improved titanium recovery. However, the disintegration of pellets during the reduction process presents a major barrier to industrial application. In this study, the reduction disintegration behavior and underlying mechanisms under hydrogen-based conditions were systematically investigated. The most severe disintegration was observed at 500 °C in an atmosphere of H₂/(H₂ + CO) = 0.25, where titano–magnetite [(Fe,Ti)₃O₄] was identified as the dominant phase. The complete transformation from titano–hematite [(Fe,Ti)₂O₃] to titano–magnetite occurred within 30 min of reduction. Extended reduction (60 min) further intensified disintegration (RDI_−0.5mm = 81.75%) without the formation of metallic iron. Microstructural analysis revealed that the disintegration was primarily driven by volumetric expansion resulting from the significant increase in the titanium–iron oxide unit cell volume. Raising the reduction temperature facilitated the formation of metallic iron and suppressed disintegration. These findings provide essential guidance for optimizing reduction parameters to minimize structural degradation during the hydrogen-based reduction of vanadium–titanium magnetite pellets. Full article

The current intensive development of steelmaking is being impeded by a scarcity of pure scrap. The potential to replace pure scrap with metallized raw materials that are naturally alloyed with vanadium and titanium, such as annealed unfluxed titanomagnetite pellets, could facilitate the achievement of key objectives in metallurgical development, particularly in the smelting of electric steel. The objective of this research was to produce annealed and metallized pellets from titanomagnetite concentrate under laboratory conditions, with the intention of further processing them as a commercial product in a blast furnace or as an intermediate product for the production of hot briquetted iron (HBI). The results demonstrate that pellets derived from titanomagnetite concentrate exhibit sufficient compressive strength (up to 300 kg/pellet) and a degree of metallization exceeding 90%, which aligns with the requirements for electric steelmaking. The suitability of pellets derived from titanomagnetite concentrate for use in both blast furnaces and metallization processes has been corroborated. Full article

In this work, a complete beneficiation technical route combining physical and chemical methods, namely a roasting-flotation-leaching scheme, is proposed to produce a qualified grade Ti-concentrate from altered Vanadium titanomagnetite (VTM) ore. Based on the character of the ore sample, it is recommended to recover the Ti-bearing minerals, ilmenite and anatase, as composite mineral. Pretreatment experiments indicate that the oxidation roasting (800 °C) and acid washing methods increase the flotation indexes significantly. Flotation condition tests show that the optimal conditions are a grinding fineness of −0.045 mm 83%, sulfuric acid dosage of 2000 g/t, water glass dosage of 1500 g/t, oxalic acid dosage of 200 g/t, and EM328 dosage of 1500 g/t. An open flotation circuit test obtains a flotation concentrate with a TiO₂ grade and recovery of 38.30% and 25.99%, respectively. A leaching exploration test shows that the TiO₂ grade of the flotation concentrate can be improved to 53.90%. XRD analyses reveal that the ilmenite in the VTM ore is converted into anatase and rutile during the roasting process at 600–800 °C, but pseudobrookite begins to form at 900 °C. Compared to the flotation concentrate, it is confirmed that the content of Ti-bearing minerals is increased significantly in the leaching residue. Full article

The Baima vanadium titanomagnetite deposit, located in the Panzhihua-Xichang (Panxi) metallogenic belt in China, is one of the super-large deposits in the region. The titanomagnetite upgrading process involves grinding the raw ore followed by magnetic separation. To determine the processing characteristics of the ore and assess the upgrading process, this study employs various methods and techniques, including the X-ray fluorescence spectrometer (XRF), chemical element analysis, the electron probe microanalyzer (EPMA), and the advanced mineral identification and characterization system (AMICS). The results show that the Fe grades in the upgraded raw ore, upgraded concentrate, and upgraded tailings are 55.68%, 57.89%, and 15.62%, respectively. After upgrading, the titanomagnetite content increased from 77.41% to 82.10%, and the Fe distribution in titanomagnetite also increased from 91.05% to 93.14%. In the upgraded raw ore, titanomagnetite particles followed a normal distribution, with 50.44% in the 38–74 μm range. In the upgraded concentrate, titanomagnetite was concentrated in the 19–38 μm range. Based on EPMA data, the theoretical Fe grade in titanomagnetite was calculated to be 65.08%, indicating the potential for further improvement through the upgrading process. This study elucidates the mineralogical characteristics during the vanadium titanomagnetite upgrading, providing a theoretical basis to further enhance the Fe recovery rate. Full article

The traditional roasting technique using sodium salts in vanadium production has been disadvantageous due to the large consumption of energy and the emission of harmful gases. A modified process using molten salt roasting and water leaching to extract vanadium and titanium from domestic titanomagnetite concentrate was investigated. The roasting process was performed under optimal conditions: the weight ratio between the sample and NaOH of 1:1, the temperature of 400 °C, and the experiment time 90 min, and the conversion of vanadium could be maximized to 90%. The optimization of water leaching (at 60 °C for 90 min with a pulp density of 0.05 g/mL) could extract 98% of the vanadium from the roasted products into the solution, leaving titanium and iron remaining in the residue. Further purification of vanadium and titanium using the precipitation/hydrolysis process followed by calcination obtained the final products V₂O₅ and TiO₂ with high purities of 90% and 96%, respectively. A potential approach with modification of the roasting stage using NaOH was proposed, which was not only efficient to selectively extract the value metals from the titanomagnetite but also eco-friendly based on the reduction in energy consumption and emission of harmful gases. Full article

Vanadium is a significant metal, and its derivatives are widely employed in industry. One of the essential vanadium compounds is vanadium pentoxide (V₂O₅), which is mostly recovered from titanomagnetite, uranium–vanadium deposits, phosphate rocks, and spent catalysts. A smart method for the characterization and recovery of vanadium pentoxide (V₂O₅) was investigated and implemented as a small-scale benchtop model. Several nondestructive analytical techniques, such as particle size analysis, X-ray fluorescence (XRF), inductively coupled plasma (ICP), and X-ray diffraction (XRD) were used to determine the physical and chemical properties, such as the particle size and composition, of the samples before and after the recovery process of vanadium pentoxide (V₂O₅). After sample preparation, several acid and alkali leaching techniques were investigated. A noncorrosive, environmentally friendly extraction method based on the use of less harmful acids was applied in batch and column experiments for the extraction of V₂O₅ as vanadium ions from a spent vanadium catalyst. In batching experiments, different acids and bases were examined as leaching solution agents; oxalic acid showed the best percent recovery for vanadium ions compared with the other acids used. The effects of the contact time, acid concentration, solid-to-liquid ratio, stirring rate, and temperature were studied to optimize the leaching conditions. Oxalic acid with a 6% (w/w) to a 1/10 solid-to-liquid ratio at 300 rpm and 50 °C was the optimal condition for extraction (67.43% recovery). On the other hand, the column experiment with a 150 cm long and 5 cm i.d. and 144 h contact time using the same leaching reagent, 6% oxalic acid, showed a 94.42% recovery. The results of the present work indicate the possibility of the recovery of vanadium pentoxide from the spent vanadium catalyst used in the sulfuric acid industry in Jordan. Full article

Vanadium titanomagnetite is an important mineral resource. It is a raw material for ironmaking, vanadium extraction, strategic metal titanium production, and titanium dioxide production. In this study, high chromium vanadium titanomagnetite (High-Cr VTM) and ordinary iron ore were used as raw materials for pelletizing. The effect of V₂O₅ on the preparation and properties of High-Cr VTM pellets was studied. The influence of V₂O₅ on the properties of the green pellets, the compressive strength of oxidized pellets, the reduction swelling index and reduction degree, softening-melting behavior, and the migration law of Fe, Ti, and Cr in the reduction process were studied by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results show that with the increase in V₂O₅ content, the properties of the green pellets basically showed a trend of first decreasing and then increasing but all met the basic requirements of pelletizing. When the added amount of V₂O₅ in the pellet was 6%, the compressive strength of the oxidized pellet was the lowest at only 2565 N/pellet but it still met the quality requirements for pellets in blast furnace production. As the dosage of V₂O₅ increased, the reduction swelling index and reduction degree of the pellets showed a trend of first increasing and then decreasing. The addition of V₂O₅ can increase the softening initial temperature, softening final temperature, melting start temperature, and dripping temperature of the High-Cr VTM pellets, narrowing the softening interval, and expanding the melting dripping interval. The experimental results provided a data reference for revealing the influence of V₂O₅ on High-Cr VTM pellets during the blast furnace smelting process. Full article

In order to pursue the goal of low-carbon ironmaking, a new type of humic acid (HA)-based binder was applied to the preparation of oxidized pellets from vanadium-bearing titanomagnetite (VTM) in this work. Effects of the HA binder (or with limestone) on the balling, preheating, and roasting behaviors of VTM were comparatively studied with bentonite. The embedded features of each mineral phase in sintered pellets, especially the crystallization and growth state of hematite grains, were deeply investigated by XRD, optical microscopy, and SEM–EDS measures. The binder dosage can be cut down by 50% when HA was used instead of bentonite. Fine hematite grains in HA pellets evolved into plump interlocking grains with ~5% of limestone addition. Pseudobrookite and magnesioferrite spinel phase formed at the optimal sintering temperature of 1250 °C, which could hinder the crystallization of hematite and affect the strength of final pellets. Full article

As the byproduct in the smelting process of vanadium titano-magnetite, titanium-bearing blast furnace slag (TBFS) can be converted to a titanyl sulfate (TiOSO₄) solution containing MgSO₄ and Al₂(SO₄)₃ impurities via dissociation by concentrated H₂SO₄ (80–95%) at 80–200 °C, followed by leaching with H₂O at 60–85 °C. In this study, hydrated TiO₂ was prepared by hydrothermal hydrolysis of a Mg/Al-bearing TiOSO₄ solution at 120 °C and the hydrolysis law was investigated. The experimental results indicate that MgSO₄ and Al₂(SO₄)₃ accelerated the hydrolysis and significantly affected the particle size (increasing the primary agglomerate size from 40 to 140 nm) and dispersion (reducing the aggregate size from 12.4 to 1.5 μm) of hydrated TiO₂. A thermodynamic equilibrium calculation showed TiOSO₄ existed as TiO²⁺ and SO₄²⁻ in the solution, and MgSO₄ and Al₂(SO₄)₃ led to little change of [TiO²⁺], but an obvious decrease of [H⁺], which favored the hydrolysis process. At the same time, the coordination–dissociation mechanism of SO₄²⁻ and Al(SO₄)₂⁻ facilitated the lap bonding of Ti-O-Ti, promoting the growth of hydrated TiO₂ synergistically. Full article

After decades of development of the vanadium titanomagnetite (VTM) ore in the Panzhihua district changes have taken place to the ore characteristics. In addition, preliminary research carried out in this area mainly focused on the separation and extraction of iron resources and lacked a systematic research focus on the process mineralogy of ilmenite, resulting in a low grade and yield of the separated ilmenite. Therefore, the present study investigates the compositions, textures, element distributions, and particle size characteristics of VTM ores in Panzhihua were studied via mineral dissociation analysis (MLA), electron microscope–microprobe analysis (EPMA), scanning electron microscopy (SEM), and X-ray diffraction (XRD). The results show that the chemical and mineral compositions of the VTM ore samples were basically stable. However, the size of the embedded particles of ilmenite and titanomagnetite was smaller than that reported previously. In addition, the olivine content was found to have significantly increased, and a large number of altered minerals (such as chlorite and sphene) were also present, as a result of which the degrees of monomer dissociation of ilmenite and titanomagnetite reached 85% when the fraction of particles with size in the range of 0.04–0.15 mm was 75%. Full article

Vanadium titanomagnetite (VTM) is an important mineral for developing titanium resources, but the comprehensive recovery of ilmenite separation is extremely poor, resulting in the low-efficiency utilization of titanium resources. Here, the separation of ilmenite from VTM ore is studied by combining magnetic separation and flotation technologies. In particular, the floatability of mixed MOH/PG-1 collectors is thoroughly investigated. The results show that a concentrate with a TiO₂ grade of 9.90% can be separated via weak magnetic separation and coarse particle tailing dumping. The concentrate grade is then increased to 14.32% via strong magnetic separation and floating separation of sulfur minerals. Finally, a TiO₂ grade of 46.34% is obtained through closed-circuit flotation using mixed MOH/PG-1 collectors. The mixed collectors are very efficient and can enhance the chemical adsorption of the Ti⁴⁺, Fe³⁺, and Fe²⁺ ions in the ilmenite concentrate compared with the MOH collector, thereby increasing the TiO₂ grade and recovery by 3.31% and 1.20%, respectively. This is beneficial for improving the comprehensive utilization of titanium resources in VTM ores. Full article

Blast furnace–basic oxygen furnace (BF–BOF) process is the predominant method for smelting vanadium titano-magnetite (VTM) in China. Hydrogen-rich (H₂-rich) gas injection in BF is considered as an important way to reduce CO₂ emission under the background of low carbon metallurgy. In this paper, the softening–melting behaviors of VTM sinter in H₂–rich gases were investigated by the method of determination of its reduction softening drippinger performance under load. The experimental results indicated that the permeability of VTM sinter during the softening–melting process was improved by increasing the H₂ content of the reducing gases. The maximum pressure drop of the burden decreased gradually from 29.76 kPa to 19.97 kPa, and the total characteristic value (representing the comprehensive softening–melting property) also decreased obviously from 2357.52 kPa·°C to 630.94 kPa·°C with the increase in H₂ content. The softening interval of the samples was widened, while the melting–dripping interval increased firstly and then decreased. In that case, the position of the melting–dripping zone in BF would move downwards, which was beneficial to smelting smoothly. The thermodynamic analysis indicated that Ti- and Fe-bearing phases were more difficult to be reduced than iron oxides, and H₂-rich gas is beneficial to the reduction of that kind of oxides. Titano-magnetite will be reduced stepwise to form Fe₂TiO₄, and then in the order of FeTiO₃→TiO₂→Ti(C,N). Wustite (FeO) was an important component during the slag-forming process, whose content increased firstly and then decreased. Perovskite and silicate were the main phases in the dripping slag samples. Full article

V-bearing molten iron was obtained by adding Na₂CO₃ in the smelting process of vanadium titanomagnetite at low temperature. Two forms of V-rich carbides ((Fe,V)₃C, VC) were detected in the V-bearing pig iron products. Once the smelting temperature was above 1300 °C, most of the V in the raw ore was reduced into molten iron. Owning to the high content of V, the unsteady (Fe,V)₃C solid solution decomposed along with the precipitation of graphite and VC during the solidification process. The presence of VC cluster and VC precursor in (Fe,V)₃C was detected by transmission electron microscopy, which confirmed the possibility of this transition process at the atomic perspective. The transformation dramatically affected the compositions and properties of V-bearing pig iron and had important guiding significance for the actual production process. Full article

The iron and steel industry is a major CO₂ emitter and an important subject for the implementation of carbon emission reduction goals and tasks. Due to the complex ore composition and low iron grade, vanadium–bearing titanomagnetite smelting in a blast furnace consumes more coke and emits more carbon than in an ordinary blast furnace. Injecting hydrogen–rich gas into blast furnace can not only partially replace coke, but also reduce the carbon emission. Based on the whole furnace and zonal energy and mass balance of blast furnace, the operation window of the blast furnace smelting vanadium–bearing titanomagnetite is established in this study on the premise that the thermal state of the blast furnace is basically unchanged (raceway adiabatic flame temperature and top gas temperature). The effects of different injection amounts of hydrogen–rich gases (shale gas, coke oven gas, and hydrogen) on raceway adiabatic flame temperature and top gas temperature, and the influence of blast temperature and preheating temperature of hydrogen–rich gases on operation window are calculated and analyzed. This study provides a certain theoretical reference for the follow–up practice of hydrogen–rich smelting of vanadium–bearing titanomagnetite in blast furnace. Full article