Reaction Mechanism of Calcium Vanadate Formation in V-slag/CaO Diffusion System

Yue, Hongrui; Xue, Xiangxin; Zhang, Weijun

doi:10.1007/s11663-021-02067-z

Cited by 10 publications

(5 citation statements)

References 29 publications

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“…The XRD pattern showed in Figure 1a shows that the main crystal structures in the HCVS were Fe 2 O 3 , FeCr 2 O 4 , MgFe 2 O 4 , Fe 2 VO 4 and Fe 2 SiO 4 [27,28,30]. The vanadium and chromium mainly existed as spinel structures (FeCr 2 O 4 and Fe 2 VO 4 ), which are hard to destroy.…”

Section: Characterization Of Hcvsmentioning

confidence: 99%

“…The roasting process is similar to the sodium-roasting process; the vanadium-containing ores are mixed with lime, limestone, and calcium salts at fixed mole ratios and then roasted at high temperatures, which are higher than with sodium roasting. During the roasting process, the vanadium spinel is decomposed and reacted with calcium salts to form different kinds of calciumvanadate, which are determined by the mole ratio of the vanadium to calcium salts [26][27][28][29][30]. Usually, some leaching enhancing processes or multiple roasting processes accompany this process to achieve high recovery [16,[31][32][33][34].…”

Section: Introductionmentioning

confidence: 99%

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Efficient Recovery of Vanadium from High-Chromium Vanadium Slag with Calcium-Roasting Acidic Leaching

Peng

Shi

et al. 2022

Minerals

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High-chromium vanadium slag (HCVS) is an important by-product generated during the smelting process of high-chromium-vanadium-titanium-magnetite. Direct acid leaching and calcium-roasting acid leaching technology were applied to recover vanadium and chromium from HCVS. The effects of experimental parameters on the leaching process, including concentration of H2SO4, reaction temperature, reaction time, and liquid-to-solid ratio, were investigated. The XRD and UV-Vis DRS results showed that vanadium and chromium existed in low valence with a spinel structure in the HCVS. The Cr-spinel was too stable to leach out; no more than 8% of the chromium could be leached out both in the direct acid leaching process and calcium-roasting acid-leaching process. Most low valence vanadium could be oxidized to high valence with calcium-roasting technology, and the leaching efficiency could be increased from 33.89% to 89.12% at the selected reaction conditions: concentration of H2SO4 at 40 vt.%, reaction temperature of 90 °C, reaction time of 3 h, liquid-to-solid ratio of 4:1 mL/g, and stirring rate of 500 rpm. The kinetics analysis indicated that the leaching behavior of vanadium followed the shrinking core model well, and the leaching process was controlled by the surface chemical reaction, with an Ea of 58.95 kJ/mol and 62.98 kJ/mol for direct acid leaching and roasting acid leaching, respectively.

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Section: Characterization Of Hcvsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Efficient Recovery of Vanadium from High-Chromium Vanadium Slag with Calcium-Roasting Acidic Leaching

Peng

Shi

et al. 2022

Minerals

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“…However, the reactions in roasting V-slag are carried out in the solid state, and the vacancy diffusion theory applicable to solid-solid reactions should be used to describe the reaction mechanism. In previous studies, [14,15] the analysis method of diffusion couple-EPMA was applied to V-slag/CaO system to explore the reaction mechanism that would be more suitable for the diffusion reactions in roasting V-slag. Herein, the authors continue to use the vacancy mechanism to describe the reactions in roasting V-slag with CaO 2 .…”

Section: Reaction Mechanism During Roastingmentioning

confidence: 99%

“…Most of the reactions during roasting V-slag contain solid phases, and the authors have studied the reaction mechanism through diffusion couple-electron probe microanalysis (EPMA) technology. [14,15] It was found that the diffusion of oxygen into the V-slag is the control process during the formation of vanadate. Moreover, even for the saturated oxide V 2 O 5 , the oxygen in the atmosphere can still promote the formation of vanadate in the diffusion system.…”

Section: Introductionmentioning

confidence: 99%

A Novel Method of Recovery Vanadium from Vanadium Slag through CaO₂‐Briquetting Roasting Process

Yue

Cheng

Liu

et al. 2022

steel research int.

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This study proposes a clean and effective routine and aims to solve the problems of material accumulation and hypoxia during roasting vanadium slag. The vanadium slag and CaO2 powders are mixed, briquetted, and roasted at different parameters. The generated phases are Fe2O3, Fe–Mg oxides, Fe–Ti oxides, Ca3(VO4)2, silicate, and SiO2 after roasting. The solid reaction between V2O5 and CaO is described using the vacancy diffusion mechanism. Ca2+ (or V5+) jumps and diffuses through the Ca2+ (or V5+) vacancies in the Ca3(VO4)2 layer and subsequently to the Ca3(VO4)2/V2O5 (or Ca3(VO4)2/CaO) interface and reacts with V2O5 (or CaO) and O2 (decomposed from CaO2 or transported from the air) to generate Ca3(VO4)2. The vanadium leaching rate is very sensitive to the roasting parameters of CaO/V2O5 molar ratio, temperature, time, and briquetting pressure. A maximum vanadium leaching rate of 98.31% is achieved with a CaO/V2O5 molar ratio of 3/1, with temperature, time, and briquetting pressure being maintained at 900 °C, 50 min, and 10 MPa, respectively. The present routine, which greatly shortens the roasting time, can be realized through a rotary hearth furnace, and is likely to be accepted by both iron works and the environment due to its effective and clean characteristics.

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“…[2] However, the production process for vanadium pentoxide includes sodium roasting of vanadium slag, leaching, ammonium precipitation, filtration, and fusion. [3][4][5][6] This cumbersome production process results in high costs and produces hazardous leaching waste containing highly toxic V 5þ and Cr 6þ ions, which leads to environmental pollution problems and is contrary to the requirements of a green metallurgical process. Hence, there is an urgent need to explore short process, low-cost, and green technologies for the production of FeV alloy.…”

Section: Introductionmentioning

confidence: 99%

Evolution of Viscosity and Structure Property during Aluminothermic Reduction of Vanadium‐Enriched Slag

Zhang

Chen

Sun

2022

steel research int.

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Aluminum dross is a promising reductant for extracting vanadium to enable the direct production of ferrovanadium alloy in pre-reduced vanadium-rich slag (PVS). The evolution of the viscosity of PVS is measured with various A/M ratios (w()), representing different reduction stages. The compositions and structural properties of the melts are analyzed using X-ray powder diffraction, scanning electron microscopy, and Raman spectroscopy. The results show that with an increase in the mass ratio of Al 2 O 3 to (FeOþCr 2 O 3 þMnOþV 2 O 3 þAl 2 O 3 ) in the slag transformed from a solid-liquid mixture to a single liquid phase at 1873 K. When A/M increases from 0.29 to 0.53, Q 0 and Q 1 polymerize into Q 2 , resulting in a slow increase in viscosity from 0.091 to 0.158 Pa s. As A/M further increased to 1.00, Q 0 disappeared, Q 3 appeared, and the fraction of Al-O-Si increased to 37.7%, indicating that the simple aluminosilicate structural units are polymerized into complex structural units. Meanwhile, the viscosity increases to 0.338 Pa s. Al 2 O 3 acts as a network former and strengthens the degree of polymerization of the melt. The variation ranges of the apparent activation energy, structural complexity, and the average number of non-bridging oxygen are 139.23-215.12 kJ mol À1 , 0.57-2.97, and 2.16-1.05, respectively.

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Reaction Mechanism of Calcium Vanadate Formation in V-slag/CaO Diffusion System

Cited by 10 publications

References 29 publications

Efficient Recovery of Vanadium from High-Chromium Vanadium Slag with Calcium-Roasting Acidic Leaching

Efficient Recovery of Vanadium from High-Chromium Vanadium Slag with Calcium-Roasting Acidic Leaching

A Novel Method of Recovery Vanadium from Vanadium Slag through CaO₂‐Briquetting Roasting Process

Evolution of Viscosity and Structure Property during Aluminothermic Reduction of Vanadium‐Enriched Slag

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Reaction Mechanism of Calcium Vanadate Formation in V-slag/CaO Diffusion System

Cited by 10 publications

References 29 publications

Efficient Recovery of Vanadium from High-Chromium Vanadium Slag with Calcium-Roasting Acidic Leaching

Efficient Recovery of Vanadium from High-Chromium Vanadium Slag with Calcium-Roasting Acidic Leaching

A Novel Method of Recovery Vanadium from Vanadium Slag through CaO2‐Briquetting Roasting Process

Evolution of Viscosity and Structure Property during Aluminothermic Reduction of Vanadium‐Enriched Slag

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A Novel Method of Recovery Vanadium from Vanadium Slag through CaO₂‐Briquetting Roasting Process