Vanadium Precipitation Research Articles

Fusion–Extraction Technique of Vanadium(III) Using Ammonium Phosphate Salt as Flux

This study presents an alternative fusion method for sample dissolution and extraction of vanadium from an inorganic (V2O3) compound and mineral ore sample (AMIS 0501) using phosphate salts as flux. Complete sample dissolution was achieved at 800 °C within ±20 min using both the sodium and ammonium phosphate flux. The precipitation of vanadium was subsequently achieved after the fusion of the sample using ammonium phosphate flux, and no precipitate was obtained using sodium phosphate flux. The differences in cations between the two fluxes (NH4+ and Na+) influenced the precipitation of vanadium. The XRD analysis of the precipitate from V2O3 using ammonium phosphate showed a monoclinic structure of vanadium (III) tris(metaphosphate) (V(PO3)3) compound, which belonged to the Ic space group with lattice parameters a = 10.6071, b = 19.0871 and c = 9.4230. A remarkable vanadium recovery of 98% was obtained from inorganic compounds, V2O3, and up to 70% from the AMIS mineral ore sample using the ammonium phosphate flux method. The vanadium precipitates from AMIS contained Fe (20.97%) and Ti (44.97%), which occurred as impurities in the recovery of vanadium using the ammonium phosphate flux method.

Vanadium precipitation from electrokinetic remediation effluent of catalytic cracking catalyst

Vanadium precipitation from electrokinetic remediation effluent of catalytic cracking catalyst

Exploration of process optimization for recovery of sodium and ammonium sulfate crystals from vanadium precipitation wastewater

In this paper, we have studied vanadium precipitation wastewater in two stages of the fractional crystallization process. In order to extract sodium sulfate and ammonium sulfate products with large particle size and uniform particle size distribution from the rear end vanadium precipitation wastewater and to realize the resource reuse of vanadium precipitation wastewater, the effects of various operating parameters (seeding amount, evaporation rate, stirring rate, growing time) on the particle size and particle size distribution of sodium sulfate and ammonium sulfate products were investigated. Better separation and crystallization conditions of sodium sulfate and ammonium sulfate were obtained. The optimized crystallization conditions of sodium sulfate are: the addition amount of ammonium sulfate seeding with a particle size of 40 μm is 1.17 %, the evaporation rate is 100 mL/h, the stirring rate is 80 rpm, the crystal growth time is 60 min, and the main particle size M.S. value of sodium sulfate crystals is 242.23 μm; The optimized crystallization conditions of ammonium sulfate were as follows: the addition amount of sodium sulfate seeding with a particle size of 80 μm was 0.68 %, the evaporation rate was 160 mL/h, the stirring rate was 150 rpm, and the crystal growth time was 30 min. The M.S. value of the final ammonium sulfate crystal was 880 μm.

Efficient recovery of vanadium using lysine

This study presents an environmental-friendly technique for vanadium precipitation using lysine. Experimental results indicate that 99.4 % of the vanadium is precipitated under the select reaction conditions within the lysine. During the precipitation process, the vanadium exists as negatively charged polyoxometalates, while the lysine is positively charged. The negative vanadium polyoxometalates precipitate out through electrostatic interactions. The results shown in this study introduce a new way to utilize lysine and a new treatment for polyoxometalates.

Separation of vanadium and chromium by selective adsorption by titanium-based microspheres

The separation and recovery of V(V) and Cr(VI) from solution can achieve the dual purpose of resource utilization and environmental protection. In this work, amorphous titanium-based microspheres with a large specific surface area of 574.86 m2/g were prepared by the simple hydrolysis of titanium alcohol. This adsorbent exhibited excellent adsorption of V(V) and Cr(VI), with maximum capacities of 153.2 and 54.21 mg/g, respectively. Most importantly, in V(V)/Cr(VI) mixed solution, selective adsorption of V(V) can be achieved by competitive adsorption. The Dubinin-Radushkevich isotherm model and Elovich kinetic model yielded the best fit for experimental data, which indicated the adsorption of V(V) and Cr(VI) onto titanium-based microspheres is a combination of chemical adsorption and physical adsorption. Selective adsorption can be achieved when sufficient V(V) was present in the V(V)/Cr(VI) mixed solution (pH 3), which is due to H3V10O283− has the more negative values of Eads (-188.12 kJ/mol) and ΔG0 (−40.72 kJ/mol). The column experiment showed promise for application in the continuous removal and separation of V(V) and Cr(VI) from wastewater to obtain qualified pure V(V) and Cr(VI) products. Through the adsorption of different concentrations of V(V)-Cr(VI) solutions, real vanadium leaching solution and real vanadium precipitation wastewater, the purification of high-concentration solutions and the treatment of low-concentration solutions could be realized.

ϕ–pH diagrams and kinetics of V2O3 prepared by solution-phase hydrogen reduction

Solution-phase hydrogen reduction (SpHR) was introduced into V2O3 preparation to overcome disadvantages of traditional reduction roasting, which include a long process, high energy consumption, and generation of pollution. The research mainly focuses on ϕ–pH diagrams and kinetics of SpHR. Thermodynamic analysis of ϕ–pH diagrams for the V–H2O system demonstrates that V2O3 preparation via SpHR requires a high temperature, a high vanadium concentration, and sufficient hydrogen in acidic solution. Kinetic analyses show that the activation energy of V2O3 preparation via SpHR is 38.0679 kJ/mol, indicating that the reduction is controlled by a combination of interfacial chemical reaction and internal diffusion. Effects of H2 partial pressure (slope K=0.05246) on the reaction rate is not as significant as the vanadium concentration (K=1.58872). V2O3 crystals with a purity of 99.59% and a vanadium precipitation rate of 99.83% were obtained under the following conditions: pH=5–6, c(V2O5)=0.5 mol/L, p(H2)=4 MPa, m(PdCl2)=10 mg, T=250 °C, and t=2.5 h.

A Sustainable Technique to Prepare High-Purity Vanadium Pentoxide via Purification with Low Ammonium Consumption.

The general preparation method for V2O5 is ammonium salt vanadium precipitation, which inevitably produces large amounts of ammonia nitrogen wastewater. In this paper, we propose an environmentally friendly method for preparing high-purity V2O5 with low ammonium consumption. The purity of the V2O5 product reaches more than 99% while reducing the level of ammonium consumption. The vanadium precipitation efficiency reaches 99.23% and the V2O5 purity of the product reaches 99.05% under the following conditions: precipitation time of 1.5 h, precipitation temperature of 98 °C, initial precipitation pH of 2, ammonium addition coefficient of 2, purification time of 5 min with purification performed twice, purification temperature of 65 °C. In this study, compared with the use of ammonia spirit for vanadium precipitation and ammonium salt vanadium precipitation, the ammonia consumption levels are reduced by 79.80% and 80.00%, and the purity levels are increased by 0.70% and 1.01%, respectively. The compositions of the precipitated (NaV3O8∙xH2O) and purified ((NH4)2V6O16·1.5H2O) hydrolysis products are characterized via XRD. The TGA results show that NaV3O8∙xH2O contains 1.5 times the amount of crystal water. The FTIR results explain that the two V3O8− layers are combined end-to-end to form a V6O162− layer. The change of the product image indicates that the purification process includes three stages. Firstly, heating and NH4+ attack expand the V3O8− layer. NH4+ diffuses more easily into the V3O8− layer. Secondly, NH4+ destroys the electrostatic interaction between Na+ with the V3O8− layer and replacing Na+. Finally, V3O8− is polymerized into V6O162− to keep the crystal structure stable.

Extraction and separation of chromium from the solution after hydrolysis precipitation of vanadium

ABSTRACT The qualified chromium oxide product was prepared successfully using acidic chromium solution after hydrolysis precipitation of vanadium based on sodium salt roasting-water leaching process in high chromium vanadium slag. The reduction conditions of sodium thiosulfate were provided. The influences of various factors on the filtration performance of chromium hydroxide were discussed, including precipitation agents, precipitation modes and precipitation temperature. The effects of chromium hydroxide calcination conditions and washing mode on the quality of chromium oxide were investigated. The results indicated that Na2S2O3 can completely reduce the acidic chromium solution, the reduction pH was less than 4.0, and the mass ratio of Na2S2O3 to Cr(VI) in the solution was 3.1. When the temperature was higher than 60°C, chromium hydroxide obtained by parallel flow precipitation using sodium carbonate as precipitant performed much better in filtration. The washed chromium hydroxide was calcined at 1200°C for 2 h. The final product of Cr2O3 with a purity of 98.76% was obtained after grinding and washing appropriately.

Analysis of Hydrometallurgical Methods for Obtaining Vanadium Concentrates from the Waste by Chemical Production of Vanadium Pentoxide.

The paper describes hydrometallurgical methods to recycle wastes of vanadium pentoxide chemical fabrication. Sludges containing a significant amount of V2O5 can be considered as an additional source of raw materials for vanadium production. We studied the one-stage leaching method using various iron-based reductants for converting V5+ to V4+ in a solution allowing to precipitate V when its concentration in the solution is low. As a result of the reduction leaching with further precipitation, we obtained concentrates with V2O5 content of 22–26% and a high amount of harmful impurities. Multistage counterflow leaching can be used to fabricate solutions with vanadium pentoxide concentration suitable for vanadium precipitation by hydrolysis and adding ammonium salts. The solutions with V2O5 content of ≈15 g/L can be obtained from the initial sludge by three-stage counterflow vanadium leaching. A concentrate with a content of 78 wt% V2O5 can be precipitated from these solutions at pH = 2.4 by adding ammonium chloride. Additionally, concentrate with V2O5 content of ≈94 wt% was precipitated from the solution with a concentration of >20 g/L V2O5 obtained from the roasted sludge. The concentrates were purified for increasing the vanadium content to 5–7%. The consumption and technological parameters of the considered processes are presented in the paper.

Effect of Hydrolysis on Vanadium Precipitation with Acidic Ammonium Salt from High Concentration of Alkaline Vanadium Solution

Effect of Hydrolysis on Vanadium Precipitation with Acidic Ammonium Salt from High Concentration of Alkaline Vanadium Solution

Exploration of Process Optimization for Recovery of Sodium and Ammonium Sulfate Crystals from Vanadium Precipitation Wastewater

Exploration of Process Optimization for Recovery of Sodium and Ammonium Sulfate Crystals from Vanadium Precipitation Wastewater

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%.

A novel method to prepare high-purity V2O5 from Na3VO4 solution

The current study presents a novel method to prepare high-purity V2O5 from Na3VO4 solution. This process characterizes Na3VO4 calcification separation, Ca10V6O25 ammoniation and solubilization, NH4VO3 crystallization, and vanadium precipitation, which achieves elemental V migration from the Na3VO4–Ca10V6O25–NH4VO3–V2O5 phase, finally obtaining high-purity V2O5. The influencing factors of the preparation process were investigated, and the results showed that vanadium was released from Na3VO4 solution to synthesize Ca10V6O25 in the first stage under the most suitable conditions (Ca/V molar ratio of 1.8, and a concentration of NaOH less than 160 g/L). In the second stage, the leaching efficiency of vanadium reached 95% at optimal conditions (NH4+/V molar ratio was 1.2, reaction temperature and time were 90 °C and 30 min, respectively). In the third stage, NH4VO3 yield and crystal size reached maximum values under optimal conditions (feed rate, crystallization temperature, and the power factor of the circulating pump were 6 m3/h, 30 °C, and 80% respectively). Finally, high-purity V2O5 was prepared via a series of large particle NH4VO3 post-treatments. In addition, the ICP analysis confirmed that the purity of the generated V2O5 was more than 99.5%.

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.

Hydrothermal precipitation of V3+ ions in V-bearing oxalic acid leachate to prepare V2O3

In our previous study, a novel method of direct leaching of V3+ ions in iron vanadate spinel minerals by oxalic acid synergized with Fe powder under hydrothermal conditions was developed. In the present study, we attempted to prepare V2O3 from this V-bearing oxalic acid leachate. First,the dissolution and precipitation behavior of V3+ ions in the V2O3-H2C2O4-H2O system were investigated at various mass ratios of V2O3 to H2C2O4 and temperatures. Then, according to the hydrothermal features of this system, two routes of preparing V2O3 were designed. In Route A, a certain amount of pure V2O3 reagent was added into the pregnant leachate as a nucleating agent and to adjust the ratio of V3+ to C2O42− ions in solution, and V2O3 was prepared from the V-bearing oxalic acid leachate by a one-step hydrothermal process. In Route B, a precursor composed of hybrid vanadium oxides was initially obtained from the V-bearing oxalic acid leachate by hydrothermal precipitation, and then the precursor was reduced in a 95% Ar + 5% H2 atmosphere at 700 °C to prepare the V2O3 product. Whether by route A or B, a V2O3 product with high crystallinity was obtained from the V-bearing oxalic acid leachate, and a higher extent of vanadium precipitation was achieved.

Controlled Hydrothermal Precipitation of Alunite and Natroalunite in High-Aluminum Vanadium-Bearing Aqueous System

During the acid leaching process of black shale, with the destruction of the aluminosilicate mineral structure, a large amount of aluminum (Al) is leached, accompanied by the release of vanadium (V). To separate aluminum from the vanadium-containing solution, the precipitation behavior of aluminum ions (Al3+) was investigated under hydrothermal conditions with the formation of alunite and natroalunite. In the solution environment, alunite and natroalunite are able to form stably by the Al3+ hydrolysis precipitation process at a temperature of 200 °C, a pH value of 0.4 and a reaction time of 5 h. When Al3+ was precipitated at a K/Al molar ratio of 1, the aluminum precipitation efficiency and the vanadium precipitation efficiency were 64.77% and 1.72%, respectively. However, when Al3+ was precipitated at a Na/Al molar ratio of 1, the precipitation efficiency of the aluminum decreased to 48.71% and the vanadium precipitation efficiency increased to 4.36%. The thermodynamics and kinetics results showed that alunite forms more easily than natroalunite, and the reaction rate increases with increasing temperature, and the precipitation is controlled by the chemical reaction. Vanadium loss increases as the pH value increases. It can be deduced that the ion state of tetravalent vanadium (VO2+) was transformed into the ion state of pentavalent vanadium (VO2+) in the hydrothermal environment. The VO2+ can be adsorbed on the alunite or natroalunite as a result of their negative surface charges, ultimately leading to vanadium loss.

Thermodynamic and Kinetic Studies on Adsorption of Vanadium with Glutamic Acid.

Many hydrometallurgy methods, including chemical precipitation, ion exchange, solvent extraction, and adsorption, have been used to recover vanadium from vanadium solution, but the final step of these methods involved precipitation with ammonium salts, high concentrations of which are harmful to the environment. The key point is to find a new compound to replace ammonium salts without reducing the vanadium precipitation efficiency. The adsorption process of vanadium with glutamic acid is investigated. The effects of experimental factors, including dosage of glutamic acid, reaction temperature, concentration of H2SO4, and reaction time, on the adsorption process are investigated. The results show that nearly 91.66% vanadium is adsorbed under the following reaction conditions: reaction temperature of 90 °C, H2SO4 concentration of 20 g/L, glutamic acid dosage at n(glu)/n(V) = 3.0:1, and reaction time of 60 min. The response surface methodology is applied to optimize the reaction conditions. The analysis results indicate that the reaction temperature has the greatest effect on the adsorption efficiency of vanadium and the influence of experimental factors follows the order: reaction temperature > dosage of glutamic acid to vanadium > reaction time > concentration of H2SO4. The pseudo-second-order model is selected to describe well the adsorption kinetic behavior, and the thermodynamic analysis results indicate that the adsorption process of vanadium is unspontaneous and exothermic. The results will be useful for further applications of glutamic acid, and they provide a bright future for vanadium recovery.

New process consisting of oxidative stripping of vanadium from loaded D2EHPA organic solution with H2O2 and direct precipitation with sulfuric acid

The traditional process of extracting V(IV) with di(2-ethylhexyl) phosphoric acid (D2EHPA) uses H2SO4 for V stripping and ammonium salt for V precipitation, leading to excessive consumption of H2SO4 and NH3·H2O, which results in a large volume of ammonia‑nitrogen wastewater. To solve this issue, a novel stripping reagent, H2O2, with the multifunction of oxidation and stripping, and a new method of precipitating vanadium from a solution of vanadium peroxy compounds were introduced to replace the traditional stripping reagent and ammonium salt precipitation, which requires separate stripping, oxidation, neutralisation and precipitation steps. The oxidative stripping of V from the loaded organic system consisting of 10% D2EHPA and 5% tri-butyl phosphate (TBP) in sulfonated kerosene using H2O2 was systematically investigated. The results indicated that 98.7% of the vanadium was stripped by three-stage cross-flow stripping under mild optimal conditions. Moreover, it was found that VO(O2)2–in the strip solution decomposed into VO(O2)+under oscillating conditions and the cation was synergistically re-extracted by D2EHPA and TBP, which resulted in a significant decrease in the stripping of vanadium and poisoning of the organic phase. The use of D2EHPA alone as the extractant can effectively prevent the problems encountered when H2O2 is used as the stripping reagent. The strip liquor could be used for direct precipitation of vanadium. A precipitation efficiency of 87% was obtained by adding a small amount of H2SO4. This new process combines oxidation, stripping and direct precipitation and exhibits the advantages of a short process flowsheet, with reagent savings (~95% decrease in H2SO4 consumption and no NH3·H2O consumption compared with traditional processes), and wastewater that is free of ammonia /nitrogen.

Effect of mechanical activation on extraction of vanadium from chromium-containing vanadate solution by calcification and carbonization

The effect of mechanical activation on extraction of vanadium from chromium-containing vanadate solution by precipitation with calcium salt and leaching with sodium carbonate salt was investigated. The whole process including selective precipitation of vanadium, alkali leaching of vanadium and cyclic utilization of calcium. Compared with stirring, ball milling is more effective for vanadium precipitation under the same experiment conditions. This is because the calcium vanadate formed on the surface of Ca(OH)2 can be peeled off by mechanical activation, which can also be confirmed by SEM image, EDS spectra and XRD patterns of the precipitation. The effect of temperature ranging from 20 °C to 50 °C on vanadium leaching efficiency was studied with the other reaction conditions fixed as stirring speed of 400 r/min, NaHCO3/V molar ratio of 2.80, L/S ratio of 4:1 ml/g. It is observed that vanadium leaching efficiency exceeding 99% was obtained after only 6 min of reaction as well as leaching temperature had little influence on vanadium leaching efficiency. After filtration, the leach solution was used to prepare crystals of NH4VO3 and the leach residue was calcined to obtain CaO. The precipitation efficiency of V was 99.34% by adding CaO into chromium-containing vanadate solution according to Ca/V molar ratio 1.80 and ball milling for 90 min with 140 rpm at room temperature. Mechanical activation can not only increase the vanadium precipitation efficiency and improve the leaching performance of the precipitate, but also to realize the cyclic utilization of calcium salt and crystallization solution.

A clean method of precipitation vanadium from the vanadium bearing oxalic acid leaching solution

To achieve the clean extraction of vanadium from iron vanadate spinel minerals, vanadium has been successfully leached as [V(C2O4)3]3− complex by using oxalic acid as a leaching agent in our previous study. However, the precipitation of vanadium from the V-bearing oxalic acid leaching solution has never been reported. Therefore, an environment-friendly hydrothermal precipitation method was applied in vanadium precipitation process in this study. Firstly, vanadium was effectively precipitated from the V-bearing oxalic acid leaching solution by hydrothermal decomposition of [V(C2O4)3]3− complex ions at the temperature above 200 °C to obtain a mixture of vanadium oxides. Based on the vanadium precipitation, to further obtain high purity vanadium oxide product, the hydrothermal precipitation of VO2 from the V-bearing oxalic acid leaching solution was investigated. Before the hydrothermal reaction, an excess hydrogen peroxide solution was employed to oxidize the [V(C2O4)3]3− complex ions to form VOC2O4 in advance. Then, the effect of temperature, the quantity of added V2O5, and reaction time on the VO2 product preparation and vanadium precipitation extent were investigated. Finally, the uniform and well-crystallized VO2 (B) with 97% purity was obtained, and higher than 99% of vanadium precipitation extent was achieved under the optimum precipitation conditions.