Separation and recovery of vanadium from a sulfuric-acid leaching solution of stone coal by solvent extraction using trialkylamine

Bao

et al. 2019

Minerals

Self Cite

NaV2O5 mesocrystals were successfully synthesized from an alkaline-stripped pentavalent vanadium solution through a novel hydrothermal hydrogen reduction process. The optimal conditions for the hydrogen partial pressure, reaction temperature, initial solution pH value, and reaction time for the pure-phase NaV2O5 synthesis were ascertained to be 4 MPa, 200 °C, 4.0, and 2 h, respectively. The synthesis time (only 2 h) was greatly shortened, by nine times, compared with the most time-saving (18 h) hydrothermal process at present. X-ray diffraction (XRD) analysis revealed that the as-prepared powders demonstrated a typical layered orthorhombic structure of NaV2O5. The purity of the as-prepared NaV2O5 reached up to 99.98%. An electrochemical test showed that the as-prepared NaV2O5 has a potential application in sodium ion batteries. According to scanning electron microscopy (SEM) and transmission electron microscopy (TEM) analyses, the as-prepared NaV2O5 powders were identified to have rod-like mesocrystals consisting of small rods which preferentially grow along the (010) direction. Furthermore, the phase transformation mechanism and crystal growth mechanism in NaV2O5 preparation were discussed systematically, based on which the synthesis mechanism of NaV2O5 was proposed as pentavalent vanadates pre-sedimentation, hydrogen reduction with dehydration, sodium ions insertion, and finally self-assembly oriented attachment. The synthesis process is characterized as time-saving and low-cost, and thus it may have great application prospects.

Section: Materials and Reagentsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

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A Novel Process for the Synthesis of NaV2O5 Mesocrystals from Alkaline-Stripped Vanadium Solution via the Hydrothermal Hydrogen Reduction Method

Bao

et al. 2019

Minerals

Self Cite

“…The process flow sheet for preparing the stripped V (V) solution from the vanadium-bearing shale is proposed in Figure 3 [29]. First, the vanadium-bearing shale was roasted at 1123 K for 1 h in air.…”

Section: Preparation Of Stripped V (V) Solutionmentioning

confidence: 99%

A Novel Eco-Friendly Vanadium Precipitation Method by Hydrothermal Hydrogen Reduction Technology

Bao

et al. 2017

Minerals

Self Cite

Abstract:In view of the serious pollution problems caused by the traditional vanadium precipitation process, the eco-friendly technology of hydrothermal hydrogen reduction was first applied to precipitate phase pure vanadium sesquioxide (V 2 O 3 ) products from stripped pentavalent vanadium (V (V)) solution extracted from vanadium-bearing shale. Thermodynamic analysis demonstrate the method of hydrothermal hydrogen reduction is feasible for precipitating V 2 O 3 from V (V) solution at a suitable pH range, and the reduction should better be carried out at a lower pH under the pH range in which V 2 O 3 can exist stably. The V 2 O 3 products of 99.92% in purity and a high vanadium precipitation percentage of 99.25% were achieved under a facile reaction condition of initial solution pH of 6, reaction temperature of 523 K, H 2 partial pressure of 4 MPa and reaction time of 2 h. Based on the analysis of XRD and FE-SEM with EDS for the precipitation products obtained at serial reaction times, the phase transformation mechanism was summarized to serial reductions with the phase transformation ofCompared with the two-step traditional method of precipitating vanadium with ammonium salt and roast-reduction (react at above 773 K for more than 3 h) for preparing V 2 O 3 , this method only experiences one-step reduction under a green atmosphere of H 2 gas with a lower reaction temperature of 523 K and a shorter reaction time of 2 h. Therefore, this method for vanadium precipitation is characterized by being eco-friendly, having a short process and being low-energy consumption, which has great significance for the sustainable development of vanadium industry.

“…A number of extractants have been investigated for the extraction of vanadium (IV) and vanadium (V) from their solutions, including acidic extractants such as di-(2-ethylhexyl) phosphoric acid (D2EHPA), 2-ethylhexyl phosphoric acid mono-2-ethylhexyl ester (EHEHPA), and bis(2,4,4-trimethylpentyl)-phosphinic acid (Cyanex272) [10]; basic extractants such as primary aliphatic amine Primene JM-T [11], trialkylamine (N235) [12,13], and methyltrialkyl ammonium chloride (N263) [14]; neutral extractants such as tri-n-butylphosphate (TBP) [15], trioctyl-phosphine oxide (TOPO) [16], and tri-n-octyl phosphine oxide (Cyanex 923) [17]; and chelating extractants like 5,8-diethyl-7-hydroxy-6-dodecanone oxime (LIX63) [18]. Among them, EHEHPA has been extensively studied for separating vanadium from other metal ions.…”

Section: Introductionmentioning

confidence: 99%

Preparation of Highly Pure Vanadyl Sulfate from Sulfate Solutions Containing Impurities of Iron and Aluminum by Solvent Extraction Using EHEHPA

Chen

et al. 2017

Metals

Abstract:The preparation of highly pure vanadyl sulfate from sulfate solutions containing impurities of iron and aluminumwas investigated by solvent extraction with 2-ethylhexyl phosphoric acid mono-2-ethylhexyl ester (EHEHPA) and tri-n-butyl phosphate (TBP) as the phase modifier. The extraction and stripping conditions of vanadium (IV) and its separation from iron and aluminum were optimized. Under the optimal extraction conditions, the extraction of vanadium (IV) and iron were 68% and 53%, respectively, while only 2% aluminum was extracted in a single contact, suggesting good separation of vanadium (IV) from aluminum. Sulfuric acid solution was used for the stripping. Nearly 100% vanadium (IV) and 95% aluminum were stripped, while only 10% iron was stripped under the optimal stripping conditions in a single contact, suggesting good separation of vanadium (IV) from iron. After five stages of extraction and stripping, highly pure vanadyl sulfate containing 76.5 g/L V (IV) with the impurities of 12 mg/L Fe and 10 mg/L Al was obtained, which is suitable for the electrolyte of a vanadium redox flow battery. Organic solution was well regenerated after stripping by oxalic acid solution to remove the remaining iron. The mechanism of vanadium (IV) extraction using EHEHPA was also discussed based on the Fourier transform infrared spectroscopy (FT-IR) analysis.