Vanadium Leaching Research Articles

Influence of iron content of chemically and mineralogically modified electric arc furnace slag on the hydration and environmental behaviour of composite cements

This work investigates the influence of the iron content of tailored electric arc furnace slag (EAFS) on hydration and strength development as well as associated heavy metal leaching properties of Portland composite cement. Further, the impact of limestone additions was investigated. EAFS from scrap smelting plant was used as starting material. Tailored EAFS was produced by re-melting, conditioning, and water quenching. By that, a glassy material with defined chemistry was obtained. The tailored EAFS strongly contributed to the compressive strength development between 7 and 28 days. Composite cements containing 35 wt.-% EAFS reached an activity index above 85 % after 28 days. The addition of limestone and amine-based quality improvers resulted in an increase of the reached compressive strength at all tested ages. That is linked to the accelerated and increased AFm phase formation. This effect is more pronounced for EAFS with high iron content. Contrary, C-S-H formation was promoted if EAFS with low iron content was used. Chromium leaching was not critical despite the high content in the tailored EAFS. The lowest vanadium leaching was observed for EAFS with low iron content.

Phase Transition and Vanadium Leaching Mechanism during Roasting of Vanadium‐Bearing Rock Coals

The phase transformation and vanadium leaching mechanism of stone coal during two blank calcined stages are systematically studied. Composition, structure, and morphology of the materials are analyzed by ICP‐AES, BPMA, XRD, FTIR, and SEM. The results show that the main components of stone coal are SiO2, C, aluminosilicate and FeS2, V2O5 is 0.70%. Two‐stage roasting is a process of deformation, melting, and reconstruction of stone coal, the oxidation of pyrite, decomposition of aluminosilicate, sulfation of calcite, combustion of carbon and the formation of calcium vanadate occur in the first stage, the oxidation of low‐price vanadium occurs in the second stage. At −0.074 mm ≥90%, liquid solid ratio 1.5:1, 10% sulfuric acid reaction at room temperature for 3 h, the vanadium leaching rate in each material is in the order of roasting slag>decarbonized slag>stone coal.

Mechanism and kinetics study of vanadium leaching from landfilled metallurgical residues by ultrasonic with ozonation enhancement in a low-acid medium

Landfilled metallurgical residues are valuable raw materials for the recovery of strategic vanadium resources. However, efficient separation of vanadium from these residues is challenging due to its strong oxidation resistance and coating within silicate inclusions. To address this issue, this study proposes an enhanced leaching process utilizing the synergistic effect of O3-catalyzed ultrasonic field in a low concentration sulfuric acid system. Results show that following a 10-minute O3 and ultrasonic treatment, the direct leaching rate of vanadium experienced a remarkable 46.7 % increase. Quenching experiments revealed a hierarchical order of active species within the reaction process:⋅OH >⋅O2−> H+, with⋅OH oxidation exhibiting the most pronounced capacity for disrupting the inclusion structure. Electron Paramagnetic Resonance analysis indicated that the highest⋅OH yield arose from the combined application of ultrasound and ozone. Kinetic investigations demonstrated that the vanadium leaching process is governed by interfacial chemical reactions. The activation energy of vanadium oxidation leaching under ultrasonic-O3 conditions was determined to be 40.41 kJ/mol, representing a 20.19 % reduction compared to ultrasonic conditions alone. Through the integration of analysis, characterization, and comparative evaluations, it was discerned that the synergistic impact of ultrasonic and ozone treatments significantly enhances the breakdown of silicate inclusions by low-concentration HF, particularly in the conversion of SiOSi bonds into SiOH bonds and SiF bonds. In summary, the refined leaching methodology incorporating ozone catalysis in conjunction with ultrasonic treatment provides a new idea for the separation and extraction of refractory residual vanadium.

Oxidative Leaching of Vanadium and Chromium from Vanadium Slag via a Mechanochemical Activation─Assisted Microbubbles Method

Oxidative Leaching of Vanadium and Chromium from Vanadium Slag via a Mechanochemical Activation─Assisted Microbubbles Method

Promoting the Calcified Roasting of Vanadium Slag Based on the CeO2-Catalytic Oxidation Mechanism.

Calcification roasting-acid leaching is a clean, efficient, and environmentally friendly process, but in the roasting process, the local temperature is often too high, the heat release is not timely, and the heat transfer is blocked. Furthermore, the material is easy to sinter, which affects the final vanadium extraction effect. In this paper, a small amount of CeO2 was introduced in the roasting process of vanadium slag to promote the calcified roasting. The results showed that the vanadium leaching rate reached 93.17% with the addition of 0.1 wt % CeO2 at a roasting temperature of 750 °C, which was higher than that obtained without CeO2 addition (90.00%). The results of XPS, XRD, and SEM-EDS analyses confirmed that adding CeO2 to the roasted clinker significantly increased the proportion of pentavalent vanadium to the total vanadium by up to 28.64%. O2-TPD analysis revealed an enhanced chemisorbed oxygen with the CeO2-assisted roasting, indicated the activation of oxygen by CeO2, and resulted in an enhanced oxidation of vanadium. The work in this paper establishes an alternative route for catalytic oxidation-enhanced vanadium slag roasting, which can improve the utilization of vanadium slag at relatively lower temperatures under the action of CeO2 and is of positive significance in solving the problems of sintering and energy consumption in the roasting process.

Leaching Vanadium from the Spent Denitration Catalyst in the Sulfuric Acid/Oxalic Acid Combined Solvent.

Huge amounts of spent denitration catalysts are produced annually as waste from the flue gas denitration process, which will cause resource waste and environmental pollution. It is important to develop an efficient method for the recovery of metals from spent denitration catalysts. In this work, the leaching of vanadium (V) from the spent denitration catalyst by the sulfuric acid/oxalic acid combined solvent was investigated. Factors that influence the leaching rate of V have been studied. Results showed that the optimal leaching rate was 95.65% by 20 wt % sulfuric acid and 0.3 mol·L-1 oxalic acid with a liquid-to-solid ratio of 20 mL·g-1 at 140 °C for 7 h. For further study of the leaching process, the leaching mechanism of V was explored subsequently. Results indicated that sulfuric acid provided a strongly acidic environment, which was beneficial to transformation, complexation, and redox reactions of V in the mixed acid leaching system. Meanwhile, oxalic acid with excellent complexation and reducing-dissolving properties promoted the formation of stable water-soluble VO2+. The "complex effect" generated from the combined acids was greatly favored for leaching V from the spent denitration catalyst.

Two-stage leaching of calcium and vanadium from high-calcium steelmaking slag

ABSTRACT Vanadium (V) is a critically important element in many industries. A widely used recovery process is a combination of roasting and leaching. However, roasting is an energy-intensive stage. Generally, basic oxygen furnace (BOF) slag is high in calcium (Ca) but low in V. Ca content and its chemical nature can prevent V leaching. This study presents a potential two-stage leaching process for Ca and V from BOF slag. The method is environmentally friendly using low temperatures and enabling leachate recycling. Furthermore, the utilisation rate of the slag can be higher due to Ca recovery. Ca is first leached using ammonium nitrate and nitric acid solution. The V-containing residue is directed to the second stage, where V is leached using ammonium carbonate ((NH4)2CO3). Ca leaching efficiency was 71% achieved with a low temperature (40°C) and in 20 min. > 99% of the dissolved element was Ca. Increasing the total nitrate concentration increased the leaching efficiency. Reducing the L/S ratio improved selectivity. The solid material was analysed after the leaching stages and a clear change was observed after the Ca-stage. The V leaching efficiency was 50%. > 88% of dissolved element was V (L/S 8, [(NH4)2CO3] 200 g/L, 60°C, and 60 min). Increasing [(NH4)2CO3] and L/S ratio slightly improved the leaching efficiency but decreased selectivity. The studied process implements circular economy principles and has been developed for side streams with low V concentrations. However, further optimisation and developments are required regarding the effectiveness of the process.

Supported H8PV5Mo7O40 on activated carbon: Synthesis and Investigation of influencing factors for catalytic performance.

Polyoxometalates (POMs), in particular the Keggin-type HPA-5 (H8PV5Mo7O40) are widely established as effective catalysts for acid- and redox-catalyzed reactions. Yet, they are mainly used as homogeneous catalysts, which poses challenges regarding catalyst separation. This study explores the synthesis of supported HPA-5, and its application as a heterogeneous catalyst for biomass conversion, focusing on activated carbons with diverse chemical and physical properties as support materials. Characterization of these carbons gives insights into the influence of surface area, oxygen content, and acidity on HPA adsorption and stability. Activated carbon CW20, was found to be the best support due to its high vanadium loading and effective preservation of the HPA-5 structure. It underwent various pre- and post-treatments, and the obtained supported catalysts were evaluated for their catalytic performance in converting glucose under both oxidative (OxFA process) and inert (Retro-Aldol condensation) conditions. Notably, HPA-5 supported on CW20 emerged as an exceptional catalyst for the retro-aldol condensation of glucose to lactic acid, achieving a selectivity of 15% and a conversion rate of 71%, with only minimal vanadium leaching.

Preventing Dissolution of Cathode Active Materials by Ion‐anchoring Zeolite‐based Separators for Durable Aqueous Zinc Batteries**

AbstractAqueous zinc batteries have emerged as promising energy storage devices due to their safety and low cost. However, they face challenges such as anodic dendrite formation and cathodic compound dissolution. Here, we present the development of a polymer‐matrixed zeolite separator (SZ) by synthesizing zeolite materials on a flexible polymeric membrane. This separator acts as an effective ionic barrier, preventing the leaching and shuttling of vanadium from the cathode, while significantly inhibiting the formation of by‐products and zinc dendrites. The SZ cells demonstrate stable operation for more than 400 cycles at 0.5 A g−1, with an initial capacity of 375.4 mAh g−1, and over 10,000 cycles at 15 A g−1. Notably, when pre‐anchored with vanadium ions, the SZ‐V cells exhibited excellent capacity retention of up to 94.6 % over 1000 cycles. The SZ separator featuring an ion barrier represents a crucial advancement towards the commercialization of zinc storage devices.

Preventing Dissolution of Cathode Active Materials by Ion-anchoring Zeolite-based Separators for Durable Aqueous Zinc Batteries.

Aqueous zinc batteries have emerged as promising energy storage devices due to their safety and low cost. However, they face challenges such as anodic dendrite formation and cathodic compound dissolution. Here, we present the development of a polymer-matrixed zeolite separator (SZ) by synthesizing zeolite materials on a flexible polymeric membrane. This separator acts as an effective ionic barrier, preventing the leaching and shuttling of vanadium from the cathode, while significantly inhibiting the formation of by-products and zinc dendrites. The SZ cells demonstrate stable operation for more than 400 cycles at 0.5 A g-1 , with an initial capacity of 375.4 mAh g-1 , and over 10,000 cycles at 15 A g-1 . Notably, when pre-anchored with vanadium ions, the SZ-V cells exhibited excellent capacity retention of up to 94.6 % over 1000 cycles. The SZ separator featuring an ion barrier represents a crucial advancement towards the commercialization of zinc storage devices.

Vanadium Leaching Kinetics from Calcification-Roasted Vanadium Slag in Ammonium Carbonate

Vanadium Leaching Kinetics from Calcification-Roasted Vanadium Slag in Ammonium Carbonate

Efficient recovery of vanadium from calcification roasted-acid leaching tailings enhanced by ultrasound in H2SO4-H2O2 system

Residual vanadium accounts for about 1% of calcification roasted-acid leaching tailings after industrial vanadium extraction. Vanadium pollution is primarily induced by the stacking of tailings. In this study, the conventional leaching process based on sulfuric acid is compared with the ultrasound-H2O2 synergistic enhanced process in the extraction of residual vanadium from calcification roasted-acid leaching tailings. Besides, the experimental process parameters are also optimized. Under the optimal conditions, the vanadium leaching rate increases by 63.64%, and the energy consumption decreases by 50%. The experimental enhancement mechanism is clarified by exploring the decomposition patterns of H2O2 under ultrasound in combination with the characterization results based on electron paramagnetic resonance (EPR). Under the action of ultrasound, H2O2 is effectively decomposed into •OH radicals to provide higher oxidation potential, which accelerates the reaction process. Through the characterization and analysis of the samples before and after the experiment, it is found that H2O2 enhances the cavitation effect of ultrasound. This effectively destroys the composite oxide structure on the surface of tailing particles, thus increasing the reaction area. In conclusion, the ultrasound-H2O2 synergistic vanadium leaching process exhibits broad application prospects in the management and recovery of industrial tailings.

Effect of roasting temperature on vanadium extraction, kinetics, phase transformation, and microstructure evolution of vanadium-bearing shale during suspension oxidation roasting process

Suspension oxidation roasting is an efficient method for enhancing vanadium extraction from shale ore, however, the mechanism research of the process in extracting vanadium is not complete. In this work, vanadium extraction, kinetics, phase transformation, and microstructure evolution of vanadium-bearing shale during the suspension roasting process were systematically investigated. 900 °C was the optimum roasting temperature. The higher temperature caused materials sintering and hindered vanadium leaching. The mechanical function of the thermal decomposition process of vanadium shale was the nucleation model (A1/4): f(α) = 1/4(1 − α)[−ln(1 − α)]−3 and G(α) = [−ln(1 − α)]4; Eα = 243.7362 kJ/mol and As = 16.8559 s−1. According to the X-ray diffraction (XRD) analysis results, the lattice of main vanadium-bearing minerals, such as muscovite, kaolinite, and limonite, was destroyed at 900 °C. A better vanadium leaching efficiency could be obtained at this temperature. Meanwhile, the result of Scanning electron microscope (SEM) analysis indicated that the dense layered structure transformed into a loose porous structure after the roasting at 900 °C. However, material sintering occurred and it hindered vanadium leaching when the temperature was above 950 °C. The results of XRD and SEM explained the reason for vanadium leaching rate changes with roasting temperature.

The oxidation behavior of MnO2 on the surface of a shale vanadium ore

As a typical oxidative leaching aid in the experimental study of vanadium extraction, MnO2 has a strong destructive effect on the lattice of vanadium-containing minerals. Therefore, the effect of manganese dioxide on vanadium leaching was studied by leaching test of shale vanadium ore. Firstly, the phase change, microstructure and possible structure of the compounds during the condition test were studied by EPMA, FT-IR and SEM-EPS. Then the effect of MnO2 on the leaching rate was studied by kinetics. The results show that under the action of manganese dioxide, the leaching control type is changed from chemical reaction control to mixed control type, and the activation energy is greatly reduced. Secondly, the adsorption of shale vanadium ore by manganese dioxide was characterized, and the density of states, the differential charge density under the action of MnO2 and the dissolution behavior of MnO2 on vanadium in minerals during leaching were studied. Based on the simulation results, it is found that there is a molecular orbital interaction between manganese ions and oxygen and hydrogen on the surface of minerals, which will seriously destroy the lattice of vanadium-containing minerals. The strong oxidation of manganese ions will destroy the structure and stability of the whole tetrahedron and accelerate the leaching trend. Under the action of high-valent manganese ions, Al (S7) -O (S1) bond breaks, Al (S7-O) bond breaks, and vanadium is more easily dissociated from minerals. In this paper, the leaching of vanadium from manganese dioxide was studied by the combination of leaching test, kinetics and quantum chemistry. Through the analysis of kinetics, density of states and charge distribution, the leaching process which could not be characterized by the test was analyzed in detail. It also provides a feasible reference for future research.

Upgrading the catalytic activity recovery capacity of a Ni–Mo/γ–Al2O3 catalyst via a modified remanufacturing process for residue hydrodesulfurization: Effect of acid leaching conditions and process sequence

In this study, the improvement of catalytic activity recovery capacity of a modified catalyst remanufacturing process for Ni–Mo/γ–Al2O3 catalysts in residue hydrodesulfurization (RHDS) is evaluated by comparing it with our previous study. The enhancement of catalytic activity recovery is achieved by modifying the sequence and conditions of the acid leaching process in the catalyst remanufacturing process. The proposed improved process successfully restored the collapsed pore structure caused by contaminant deposition, a major deactivation factor identified in our previous study. The selective leaching of vanadium through the addition of ferric nitrate in the acid leaching process effectively addresses the issue of simultaneous removal of active species caused by excessive leaching. Consequently, the remanufactured catalyst exhibited an impressive catalytic activity recovery of 99% compared to the fresh catalyst at a reaction temperature of 395 °C, approaching a near-perfect state. Notably, the reducibility of the catalyst emerges as a key factor influencing catalytic activity recovery. The restored pore structure and selective removal of vanadium using ferric nitrate application increase the contact area between reactants and active precursors, enhancing reducibility and leading to a higher number of active sites. Additionally, a threshold effect is observed in the recovery of catalytic activity through improved specific surface area, where the enhancement of pore diameter resulting from vanadium removal on the exterior of catalyst surface becomes crucial. These findings contribute to advancing catalyst remanufacturing processes and understanding the factors influencing catalytic activity recovery.

Photoactive TiO2-V2O5-WO3 film composites immobilized in titanium phosphate matrix by plasma electrolytic oxidation

V-, W-containing oxide-phosphate layers on titanium were obtained by plasma electrolytic oxidation (PEO) for 5 min at anode current density i = 0.08 A/cm2 in electrolytes containing 0.05 mol/L Na6P6O18 and 0.1 mol/L (Na2WO4 + NaVO3). The effect of replacing vanadate with tungstate (NaVO3:Na2WO4 = 0:1, 1:3, 1:1, 3:1, and 1:0) was studied on voltage–time responses, PEO coatings surface morphology, composition, optical and photocatalytic properties. The coatings were investigated by X-ray diffraction analysis, scanning electron microscopy, energy-dispersive X-ray microanalysis, X-ray photoelectron spectroscopy, and diffuse reflectance spectroscopy. Under experimental conditions, amorphous coatings with a thickness of 18–27 μm and a surface porosity of 1.5–3.6% were formed. Results show that vanadium (up to 10.5 at. %) and tungsten (up to 5.2 at. %) are incorporated into surface layers in proportion to their concentrations in electrolyte. The main mechanism for the incorporation of V and W into coatings is assumed to be thermolysis of vanadungstophosphate heteropolyoxoanions, while high concentrations of polyphosphate species contribute to the amorphization of coatings and the formation of a titanium phosphate matrix. The band gap of V-containing composites decreases from 2.22 to 1.97 eV as tungsten replaces vanadium. For W-containing composites (V-free ones), the band gap is 3.19 eV. All formed coatings exhibit photocatalytic activity in the degradation of methyl orange (10 mg/LMO, 10 mmol/L H2O2) in a neutral medium (pH 6.8) under visible and UV irradiation. The gradual substitution of vanadium for tungsten in the coatings leads to a decrease in MO degradation (from 87 to 50% and from 32 to 9% under 3-h UV and visible irradiation) with a simultaneous increase in their durability due to a decrease in vanadium leaching. An electrolyte with Na2WO4:NaVO3 = 1:3 is optimal for the formation of photoactive and stable composites. When using composites obtained in this electrolyte, MO conversions are 83 and 31% under UV and visible irradiation, respectively. The mechanism of the photocatalytic action of WO3-V2O5-TiO2 composites is considered, and the role of hydrogen peroxide is discussed.

Vanadium–Titanium Magnetite Concentrate, Calcium–Magnesium Composite Roasting and Sulfuric Acid Leaching for Vanadium Extraction from Pellets

This paper investigated a pellet ore production process in which vanadium was extracted from vanadium and titanium magnetite concentrates using sulfuric acid leaching. Calcium and magnesium were added to the iron ore concentrate during pellet production to produce calcium vanadate and magnesium vanadate after roasting. The pellets were leached with sulfuric acid solution to extract V5+. The resulting pellets had a compressive strength of 3375 N after primary roasting, a good pellet morphology after acid leaching, and simple liquid–solid separation. Under the optimal experimental conditions, the vanadium leaching rate in the pellets reached 77.86%, while the iron leaching rate was only 1.17%. The pellets did not fragment, which was an improvement upon existing vanadium extraction methods. The strength of the pellets after vanadium extraction decreased to 563 N, but after secondary roasting, the compressive strength of the pellets reached 2578 N, which was suitable for blast furnace ironmaking. The roasting and acid leaching experiments showed that the vanadium extraction process resulted in suitable pellet properties. The use of low compound additives can effectively improve the leaching effect, while avoiding the previous problems of too many additives, pellet iron grade reduction, or the pursuit of high vanadium extraction rate pellet breakage and serious high secondary use process costs.

Optimization and kinetic analysis of direct acid leaching of vanadium from converter vanadium slag under atmospheric pressure

Converter vanadium slag is an important kind of raw material for the production of vanadium products. Not only does the atmospheric acid leaching of vanadium from vanadium slag without roasting avoid the pollution of exhaust gas generated from roasting, but also it reduces the threat of Cr(VI) and V(V) and is conducive to the vanadium products preparation with low valence state. In this paper, the optimization of leaching conditions by response surface methodology and the direct sulfuric acid leaching kinetics of vanadium from converter vanadium slag were investigated. In the consequence of experiments, the optimum atmospheric sulfuric acid direct leaching conditions were initial sulfuric acid concentration of 4 mol/L, reaction temperature of 90 °C, reaction duration of 8 h and liquid to solid ratio of 8 mL/g with the particle size of vanadium slag below 20 μm. Under the optimum conditions, the vanadium leaching efficiency was 86.09%. The kinetics analysis demonstrated both the chemical reaction and inner diffusion were the control steps of the leaching process. The calculated apparent activation energy of the leaching process was 17.63 kJ/mol and the reaction order of sulfuric acid was 0.78.

Microstructure and Mineral Phase Evolution of Vanadium Slag by Modulating the CaO/V2O5 Ratio

The slag mineral phase is reconstructed by adding CaO to the molten vanadium slag to obtain a slag with high metallurgical characteristics. In this paper, the effects of the CaO/V2O5 ratio on the microstructure of molten vanadium slag, the phase composition of vanadium slag, and the non-salt roasting-(NH4)2CO3 leaching performance of modified vanadium slag were comprehensively investigated. Molecular dynamics simulation was used to examine the microstructure of the simplified vanadium slag system (FeO-V2Ox-SiO2-CaO) at varied CaO/V2O5 ratios. The results show that V (3+, 4+, and 5+) in the molten vanadium slag is similar to the network former. The V-O structure is dominated by four-fold coordination, and V3+ and V5+ show rich coordination configurations. With the increased CaO content, the overall diffusivity of the system increases, and the network structure is destroyed by CaO. The addition of CaO realizes the mineral phase reconstruction of vanadium slag, and vanadium slag with a more concentrated vanadium distribution and a wider Ca distribution is obtained. The concentration of vanadium in vanadium spinel increases from 17% to 29.4%. A suitable CaO/V2O5 ratio reduces the dependence of the vanadium leaching recovery on the vanadium slag’s roasting temperature and duration.

Enhanced bioleaching efficiency of vanadium from stone coal vanadium ore by adding biochar and plasma treatment

To address the common problem of low vanadium bioleaching efficiency from stone coal, different enhanced bioleaching methods were used in this study. In the single enhancement treatment of adding biochar, plasma pretreatment, and adding sodium dodecyl sulfate (SDS), the addition of 1 g of biochar had the best effect on vanadium leaching by Bacillus mucilaginosus (B. mucilaginosus), with a 9.8% higher vanadium leaching rate compared to the blank group. While, the compound enhanced treatment method, including plasma treatment of stone coal for 6 min and adding 0.1 g/L biochar in bioleaching system, can further improve vanadium leaching. At 20 days of bioleaching, the vanadium leaching rate was 21.7% higher than that of the blank group. It was found that biochar can facilitate bacterial attachment through microbial immobilization and increase bacterial biomass. The flourier transform infrared (FTIR) spectroscopy results show that the plasma pretreatment can introduce oxygen-containing functional groups such as hydroxyl and carboxyl groups to modify the surface of the stone coal, which reduced the contact angle of the stone coal by 22.1° and improved its surface hydrophilicity and reactivity, enhancing the interface reaction between B. mucilaginosus and stone coal vanadium ore. Hence, this work significantly promoted the vanadium bioleaching performance through compound enhanced bioleaching mothed, which appears very promising for the development of practical applications.