Vanadium Slag Research Articles

A new process for extracting vanadium by direct calcification using the heat of molten vanadium slag

A novel technology for extracting vanadium from molten converter vanadium slag was studied at the laboratory scale by oxidation and calcification. The effect of the cooling method, CaO addition, and reaction time on the phases of calcified vanadium slag was studied. Under the action of oxygen and CaO, the molten vanadium slag underwent calcification reaction to form acid-soluble calcium vanadate phase and the feasibility of its main chemical reaction was calculated by Factsage8.1. The calcified vanadium slag was leached by H2SO4 solution and characterized by the XRF, XRD, SEM, and EDS techniques. Compared with the traditional process, the new process saved much energy, and it was faster and more efficient. The XRD results showed that CaV2O5, Ca7V4O17, and Ca3V2O8 were gradually formed in the molten vanadium slag with increasing CaO addition. However, when too much CaO was added, Ca2SiO4 and CaTiO3 were also formed. These phases wrapped part of the vanadium and reduced the leaching rate of vanadium. When the mass ratio of Ca to V was 0.75, under the optimal acid leaching conditions (particle size of calcified vanadium slag less than 0.075 mm, leaching temperature 90 ?, H2SO4 concentration 200 g.L-1, liquid-to-solid ratio 6:1 ml.g-1, leaching time 60 min, and stirring speed 300r.min-1), the leaching rate of vanadium from calcified vanadium slag could exceed 90%. The new process not only saved energy and reduced emissions, but also reached the average level of the existing vanadium extraction process.

High Purity Vanadium Oxysulfate Electrolyte for Vanadium Redox Flow Battery Prepared from Vanadium Slag Calcified Roasting Acid Leaching Solution by Two-Stage Solvent Extraction

High Purity Vanadium Oxysulfate Electrolyte for Vanadium Redox Flow Battery Prepared from Vanadium Slag Calcified Roasting Acid Leaching Solution by Two-Stage Solvent Extraction

Effect of Chromium Content on the Phase Composition, Crystallization and Components Extraction of Vanadium Slag

Effect of Chromium Content on the Phase Composition, Crystallization and Components Extraction of Vanadium Slag

From vanadium slag to multi-cation-intercalated V2O5·nH2O: low-cost direct synthesis and high-performance aqueous battery application

Multi-ion co-pre-intercalated hydrated vanadate microflowers with a robust crystal structure from vanadium slag waste are developed, which present highly reversible and ultrafast Zn2+ storage ability at room temperature and −20 °C.

Comparison and Evaluation of Vanadium Extraction from the Calcification Roasted Vanadium Slag with Carbonation Leaching and Sulfuric Acid Leaching

Comparison and Evaluation of Vanadium Extraction from the Calcification Roasted Vanadium Slag with Carbonation Leaching and Sulfuric Acid Leaching

Research of modification influence on cracking resistance of cast iron in moulds

The research is devoted to determination of influence of grey iron modification technology; this gray iron is used for manufacture of steel casting moulds. Difficult operating conditions stipulate strict requirements both on construction of moulds and on their materials. These moulds materials should reliably withstand to effect of cast steel with the temperature 1600–1700 °C, as well as to thermal shock which is directly proportional to this temperature, to essential cyclic thermal stresses and deformations. Peculiar operating conditions of moulds (such as high heating temperature, mounting on movable and stationary runners, intensive traffic routes etc.) hamper conduction of the required investigations directly during their operation. The research was carried out on physical models of moulds for consumable electrodes of vacuum arc remelting with geometrical similarity scale 1:10. The following mould models for consumable electrodes, cast of iron, were tested: modified by ferrosilicon FS65 (according to the GOST 1415-93), modified by primary aluminium A99 (according to the GOST 11069-2001), modified by vanadium slag ShVD-1 (according to the technical specification TU 14-11-178-86), modified by ferrosilicobarium FSB-30 and by silicomishmetal SIMISh-1. These modifiers were selected owing to their wide use at production facilities. Thereby, the conducted tests were aimed to examine the features of moulds walls deformation and stress-strain state on the models of gray and modified cast iron; they allowed to assess the advantages and disadvantages of obtained structure and graphite inclusions forms. They will also help to develop the most rational form of external surface for moulds designed for section and sheet metal, previously determining destruction features. Application of thinwalled moulds with rational form can provide substantial decrease of their specific consumption. Examination of metal quality which was cast in pilot (lightened) moulds with curved external surface displayed that metal macrostructure for pilot and usual ingots is the same.

Direct Vanadium Alloying of Liquid Steel with Self‐Reduction Vanadium Slag Briquette

Herein, a green and innovative direct alloying technology of liquid steel with self‐reduction vanadium slag briquette is proposed. This method with resource‐conserving, energy‐saving, and environment‐friendly, provides an alternative of the compact process for producing vanadium‐bearing steel. Thermodynamic and experimental investigations are carried out to illustrate the selective reduction tendency of oxide components in vanadium slag, recovery yield of vanadium and reaction mechanism during the direct alloying process. The reduction order of oxide components in vanadium slag briquette is FeO, Cr2O3, V2O3, and MnO, and after 20 min alloying time, the mass fraction of [V] in liquid steel climbs dramatically up to 0.56%. With increasing alloying temperature from 1520 to 1600 °C, the recovery yield of vanadium increases from 70.23% to 84.54%, and the highest vanadium recovery yield could reach 90.04% under the optimal conditions, indicating that higher temperature is essential to enhance self‐reduction reaction and mass transfer in liquid steel. The direct alloying process is controlled by the diffusion of vanadium element from the reaction interface into liquid steel through the slag‐metal boundary layer. In addition, smaller‐size vanadium slag briquette and intensified mixing of liquid steel are recommended to ensure rapid alloying and high vanadium recovery in applicable industrial production.

A novel process to prepare high-purity vanadyl sulfate electrolyte from leach liquor of sodium-roasted vanadium slag

The leach liquor of sodium-roasted vanadium slag in vanadium industry is an alkaline solution containing vanadium, sodium, chromium, and other impurities, and preparing high-purity vanadyl sulfate electrolyte (used in vanadium redox flow battery) directly from this solution is challenging but cost-effective. A novel process consisting of selective reduction–precipitation of chromium and solvent extraction of vanadium was proposed and optimized in this study. Approximately 90% of Cr(VI) in the solution was reduced to Cr(III) and precipitated after adding sodium sulfite at a pH of 5.77 and 25 °C, while V(V) remained in this process and needed a further reduction to V(IV) prior to extraction. More than 99.9% of V(IV) remained in the solution was extracted by two-stage extraction using the “P507 + TBP + kerosene” extractant system at a pH of 2.00 and an organic-to-aqueous phase ratio of 1.5:1. Sodium entrained in the organic phase was washed off through three-stage scrubbing. A high-purity vanadyl sulfate solution of 2.1 mol L−1 was prepared by two-stage stripping using 5.5 mol L−1 sulfuric acid. According to the slope analysis and infrared spectra, the extraction of V(IV) by P507 follow the cation exchange mechanism. This study provides a feasible way to remove chromium and recover vanadium in the form of vanadyl sulfate from the industrial leach liquor of sodium-roasted vanadium slag.

A green and efficient route for simultaneous recovery of low valence of vanadium and chromium, titanium and iron from vanadium slag

Traditional methods to recover vanadium from vanadium slag by oxidizing V(III) in slag to V(V) at above 800 °C, result in discharge of significant amount of residue containing Cr, Ti, Fe, and wastewater containing highly toxic V(V) and Cr(VI). Then V2O5 was reduced to low valence vanadium (LVV) for applications, such as vanadium flow battery, vanadium alloy. It is necessary to effectively utilize vanadium slag for the sustainable development of vanadium metallurgy industry. In present work, a clean method was developed to directly recover LVV from vanadium slag and valuable elements such as Cr, Ti, Fe were retrieved simultaneously, without producing V(V) and Cr(VI) bearing hazardous wastewater and residue. Vanadium slag was roasted with sulfuric acid under low temperature and then leached with water, while the volatile roasting tail gas was stripped with water. During the roasting, metal ions, V(III), Cr(III), Fe(II), Ti(IV) converted to their corresponding sulfates subsequently leached out into the leachate. Almost all of vanadium and chromium retained in the form of low valence during the process. By optimizing the roasting-leaching conditions, the best recovery of V, Cr, Ti, Fe reached 96.20%, 94.39%, 90.60%, 90.13%, respectively. This low temperature roasting process provides a new route to recover useful elements from vanadium slag without discharging wastes, it is an environmentally benign and clean technology.

Separation of vanadium and chromium in solution after vanadium precipitation by co-extraction with N263 and selective stripping with NaOH solution

The conventional process of extracting vanadium from vanadium slag produces a large amount of V-Cr-bearing residue (VCBR) and wastewater containing sulfate and ammonium salt. Through the research of the co-extraction and selective stripping of vanadium and chromium, this work proposes a novel process for extracting vanadium and chromium from vanadium slag to avoid the issues mentioned above. Methyl tri octyl ammonium carbonate (N263) can co-extract vanadium and chromium from solution after vanadium precipitation. Vanadium can be selectively stripped by NaOH solution from the loaded organic solution containing V and Cr. Under the most suitable conditions, including NaOH concentration of 3 mol/L, stripping temperature of 25 °C, O/A ratio of 3:1, the stripping of vanadium and chromium reached more than 99% and less than 8%, respectively, after five-stage counter current stripping. Chromium in the loaded organic solution can be stripped in the form of PbCrO4·PbO precipitate using the stripping system of PbCO3 + NaOH solution. Under the most suitable conditions, including PbCO3 addition with a Pb/Cr molar ratio of 5, NaOH concentration of 0.5 mol/L, O/A ratio of 1:1, stripping temperature of 25 °C, stripping time of 50 min, the stripping of chromium reached 99.1%.

Element Migration Behaviors During the Reduction of Vanadium Slag for Iron‐Removal and Vanadium‐Enrichment

The lengthy production procedures of FeV alloy from vanadium slag (VS) presently may cause high production costs and hazardous leaching liquor waste containing toxic V5+ and Cr6+ ions. A two‐step direct reduction technology is considered a short and environmental‐friendly process to solve the aforementioned problems. Solar grade silicon cutting slurry waste (SoG‐Siw) containing Si and SiC is regarded as an effective reductant to achieve comprehensive resource utilization and control reductant cost. The element migration behaviors during the reduction process are clarified from phase transitions and microcosmic features. The results showed that 78.7 wt% of Fe and 38.6 wt% of Cr migrated from slag to the metal phase with a mass ratio of pretreated SoG‐Siw (Si‐SiCmixt) to VS (S/V) of 0.15 after soaking at 1823 K for 60 min. The content of V2O3 is enriched from 12.14 to 16.13 wt%. The mass ratio of V to Fe increased from 0.28 to 1.40, satisfying the composition goal of the production of FeV60 alloy (50–65 wt% V). With an increase of S/V to 0.20, 4.6 wt% of V migrated from slag to the metal phase, causing the loss of vanadium. The reduction path is FeO → Fe2TiO4 → (Mn, Fe)(V, Cr)2O4 → (V, Cr)2O3.

Mechanisms and kinetics of a new cleaner single cyclic roasting-leaching process for the extraction of vanadium from Linz–Donawitz converter slag using CaCO3 and H2SO4

Prevailing alternative technologies of vanadium extraction from vanadium slag that suffer from high production costs, energy consumption and serious environmental pollution due to the large production of toxic solid-liquid-gaseous effluents are that non-environmental-friendly. This study implemented a new, cleaner, more effective and environmentally-friendly method of the single cyclic roasting-acid leaching, where vanadium clinker, residue and liquor can be recycled as roasting additive and leaching agent to enhance the roasting-leaching effect. The complete single cyclic roasting-acid leaching process of the chemicals, mechanisms and the maximum roasting conversion efficiency achieved in the case of vanadium is 88.86%–92.39% and leaching efficiency of 93.77%–97.61%. Herein, the recycling and reuse of all the liquor and leaching residue result in the zero-liquid discharge, solid waste reduction, significant cleanliness, and high resource utilization. This work has opened a new pathway of establishing a significantly cleaner production process for environmental sustainability via design and incorporation of inner recycling of wastes into the process in which these wastes are produced. In addition, the thermodynamics and kinetics of the whole single cyclic roasting-acid leaching process analysis can help us understand the mechanisms. All results and conclusions have guiding significance to industrial production of V2O5 from vanadium slag.

Co-extraction of Vanadium Titanium and Chromium from Vanadium Slag by Oxalic Acid Hydrothermal Leaching with Synergy of Fe Powder

Co-extraction of Vanadium Titanium and Chromium from Vanadium Slag by Oxalic Acid Hydrothermal Leaching with Synergy of Fe Powder

Evaluation of a green-sustainable industrialized cleaner production for FeV50 and FeV80 alloys from vanadium slag by calcification roasting–ammonia on-line cycle

Conventional calcification roasting–ammonium precipitate for ferrovanadium preparation have been exposed many technical problems such as roasting temperature control, leaching kinetics problem, precipitating vanadium liquor loss, reducing-melting vanadium evaporation loss and smelting vanadium evaporation loss in the process of industrialization. Therefore, a green-sustainable industrialized cleaner production for FeV50 and FeV80 alloys from vanadium slag by calcification roasting–ammonia on-line cycle is discussed. This process involves several steps including vanadium pretreatment and Fe recycling, pre-calcified vanadium slag circulating roasting, two-step circulating leaching, continuous vanadium precipitating and wastewater recycling, reducing-melting and NH3 recycling, three-stage ferrovanadium smelting. According to the theoretical base about conventional chemical, thermodynamics principles, phase diagram, dissolution kinetics, solution state diagram, separation gravity, problems, challenges and reasons analysis, the several steps including six cycles of FeV50 and FeV80 preparation were designed and industrialized. Through before and after process optimization and heat discharge, TG–DSC, XRD, SEM–EDS analysis, the mechanisms from vanadium slag to ferrovanadium help understand the increasing of the whole process vanadium yield from 57.21% to 80.81%, including vanadium oxide yield increased from 59.90% to 82.88%, ferrovanadium yield increased from 95.50% to 97.50%, respectively. All results and conclusions had guiding significance and demonstration effect on vanadium industry.

Cyclic metallurgical process for extracting V and Cr from vanadium slag: Part II. Separation and recovery of Cr from vanadium precipitated solution

Cyclic metallurgical process for separation and recovery of Cr from vanadium precipitated solution by precipitation with PbCO3 and leaching with Na2CO3 was investigated. The concentration of Cr residue in the solution decreases from 2.360 to 0.001 g/L by adding PbCO3 into vanadium precipitated solution according to Pb/Cr molar ratio of 2.5, adjusting the pH to 3.0 and stirring for 180 min at 30 °C. Then, the precipitates were leached with hot Na2CO3 solution to obtain leaching solution containing Na2CrO4 and leaching residue containing PbCO3. The leaching efficiency of Cr reaches 96.43% by adding the precipitates into 0.5 mol/L Na2CO3 solution with the mass ratio of liquid to solid (L/S) of 10:1 mL/g and stirring for 60 min under pH 9.5 at 70 °C. After filtration, leaching residue is reused in Cr precipitation and leaching solution is used to circularly leach the Cr precipitates until Na2CrO4 approaches the saturation. Finally, the product of Na2CrO4·4H2O is obtained by evaporation and crystallization of leaching solution.

A clean metallurgical process for vanadium precipitation from chromium-containing vanadate solution

The conventional process of sodium carbonate roasting-water leaching for vanadium extraction cannot be applied to high chromium bearing vanadium slag, and the production process will produce a large amount of V-Cr-bearing reducing slag and wastewater containing sulfate and ammonium salt. To avoid these questions, this work proposes a novel process for the extraction of vanadium and chromium from vanadium slag. In the current research, the vanadium precipitation part of the novel process was studied in detail. The experiment results show that weak basic ammonium bicarbonate precipitation method can realize the selective precipitation of vanadium from chromium-containing vanadate solution. The presence of Cr(VI) in the solution has a great influence on precipitation, crystallization as well as product purity of NH4VO3. Chromium can increase the solubility of NH4VO3 and reduce the supersaturation degree of NH4VO3. Furthermore, it can change the crystal morphology of NH4VO3 and affect the precipitation of NH4VO3. The precipitation of NH4VO3 increased with the increase of N/V molar ratio, but decreased with the increase of chromium concentration in the solution. The content of chromium in V2O5 increased with the increase of N/V molar ratio as well as the chromium concentration in solution. For vanadate solutions containing 2.0, 5.0, 10, 20 and 25 g/L Cr, under the most suitable vanadium precipitation conditions, the precipitation of vanadium is 83.5%, 80.1%,73.8%, 61.2% and 60.3%, respectively.

Extraction of the Rare Element Vanadium from Vanadium-Containing Materials by Chlorination Method: A Critical Review

Vanadium as a rare element has a wide range of applications in iron and steel production, vanadium flow batteries, catalysts, etc. In 2018, the world’s total vanadium output calculated in the form of metal vanadium was 91,844 t. The raw materials for the production of vanadium products mainly include vanadium-titanium magnetite, vanadium slag, stone coal, petroleum coke, fly ash, and spent catalysts, etc. Chlorinated metallurgy has a wide range of applications in the treatment of ore, slag, solid wastes, etc. Chlorinating agent plays an important role in chlorination metallurgy, which is divided into solid (NaCl, KCl, CaCl2, AlCl3, FeCl2, FeCl3, MgCl2, NH4Cl, NaClO, and NaClO3) and gas (Cl2, HCl, and CCl4). The chlorination of vanadium oxides (V2O3 and V2O5) by different chlorinating agents was investigated from the thermodynamics. Meanwhile, this paper summarizes the research progress of chlorination in the treatment of vanadium-containing materials. This paper has important reference significance for further adopting the chlorination method to treat vanadium-containing raw materials.

Study on fluidized leaching of calcified vanadium slag clinker

The fluidized leaching process of calcified vanadium slag clinker was studied in a particulate fluidized bed reactor. The particle size distribution of the clinker was determined and seven size fractions were divided for the experiments. The critical velocity and entrainment velocity of different size fractions were firstly calculated. The effects of clinker particle size on the apparent fluidization velocity, residence time and vanadium leaching rate were investigated. The results show that the critical fluidization velocity and residence time distribution of different particle size fractions are quite different, and there exists significant short circuit or channeling which needs to be treated by stages. The best vanadium leaching efficiency of 94% can be obtained for particles lower than 39 μm, with the residual vanadium content of the tailing at 0.54%.

Deep understanding of sustainable vanadium recovery from chrome vanadium slag: Promotive action of competitive chromium species for vanadium solvent extraction

The complete separation of vanadium (V) and chromium (Cr) from chrome vanadium slag is still challenging. Many studies focus on the activity of vanadium, while the effect of the other element chromium and their mutual interaction are ignored. Here, we found that proper concentration of chromium can promote the extraction efficiency of vanadium. The extraction of V and Cr with various mass ratios ranging from 8:1–4:3 at different initial pH values using primary amine N1923 were studied. The extraction efficiency of V reached nearly 100%, while none of Cr was extracted when the mass ratio of Cr and V is 0.5 under proper pH. Through the dynamic monitoring of species evolutions during extraction, the transformation of the two metals and advantage extracted species were analyzed. Cr would transfer H+ for the combination of V3O93-/V4O124-, providing a great contribution to the continuous extraction of V. The real leachate was applied and 99.9% vanadium pentoxide was produced at a scale of 50 L/h. This paper offers deep insights of the separation of similar metal elements, and guide sustainable vanadium recovery from hazardous waste.

Green preparation of vanadium carbide through one-step molten salt electrolysis

Vanadium carbide (VC) as excellent ceramic and functional material is usually prepared by carbothermal reduction of V2O5 which must be extracted from a typical V slag by complex processes. Pollutants, such as ammonia-nitrogen wastewater, NH3 and CO2 are inevitably discharged. A novel and green method for VC preparation was proposed by one-step co-electrolysis of soluble NaVO3 and CO2 in molten salt. It was found that VC with high purity was easily obtained by reducing electrolysis temperature and CO2 flow rate to 600 °C and 10 mL min−1 at 3.0 V. Besides VC with particles and layered stacking structure in products, a small amount of carbon and oxygen elements existed. The atomic percentage contents of C, V, and O elements in VC were about 50.0%, 44.5% and 3.8%, respectively. During electrolysis, CO32− and VO3− was reduced at about −0.55 V (vs. Ag/AgCl) and −1.38 V (vs. Ag/AgCl), respectively. CO32− ions were more easily reduced than VO3−, and was firstly reduced to CO22− and then converted to C. Then, VC was prepared by two routes from CO2 and NaVO3. One route is that VO3− ions are firstly electroreduced to VO2− ions and then are further electroreduced to VC with C. Another route is that VO3− ions are electroreduced to V which in-situ reacted with C to VC. Both VO3− and CO32− ions are electroreduced by two-step process. In final, VC is in-situ deposited on cathode. It provides a novel and green way to prepare VC and also achieves the high value-added utilization of vanadium slag and CO2.