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Xuewei Lv - One of the best experts on this subject based on the ideXlab platform.

  • A Multi-step Process for the Cleaner Utilization of Vanadium-Bearing Converter Slag
    Rare Metal Technology 2019, 2019
    Co-Authors: Junyi Xiang, Qingyun Huang, Wei Lv, Mingrui Yang, Kai Hu, Xuewei Lv
    Abstract:

    A multi-step process has been developed for the recovery of metal values from vanadium-bearing Converter Slag. A beneficiation process combined with grinding, sieving and magnetic separation steps was firstly utilized to recover metallic iron from the vanadium-bearing Converter Slag. Then a calcification roasting–acid leaching process was developed to recover vanadium from the vanadium Slag, forming vanadium-bearing solution and vanadium tailings. The vanadium-bearing solution can be further used to recover vanadium, and the vanadium tailings were treated by a carbothermic reduction–magnetic separation process, which generated two products, viz. ferroalloy and titanium concentrate. The ferroalloy can be used as raw materials for the steelmaking process whereas the titanium concentrate can be taken for Ti recovery. The results showed that the majority of iron, vanadium, chromium, and titanium in the vanadium-bearing Converter Slag can be fully recycled in such a comprehensive recovery process.

  • Mineralogical characterisation and magnetic separation of vanadium-bearing Converter Slag.
    Waste Management & Research, 2018
    Co-Authors: Junyi Xiang, Qingyun Huang, Wei Lv, Xuewei Lv
    Abstract:

    : The recycling of metallic iron is commonly the first step to fully use the Converter Slag, which is the biggest waste discharge in the steelmaking process. This study presents a proposed improved process of separating metallic iron from vanadium-bearing Converter Slag more efficiently. The mineralogical and morphological characteristics of the Converter Slag were first investigated, and the results showed that most of the iron was incorporated in the spinel and olivine. Grinding, sieving and magnetic separation were combined to recover metallic iron from the Converter Slag, and yielded approximately 41.5% of iron in which the iron content was as high as 85%, and the non-magnetic concentrate contains 8.56% vanadium with a yield of 95.3% and 8.63% titanium with a yield of 85.3%. The magnetic part can be used as the raw materials in the steel making process, whereas the non-magnetic part can be used as the raw materials for the further extraction of vanadium.

  • extraction of vanadium from Converter Slag by two step sulfuric acid leaching process
    Journal of Cleaner Production, 2018
    Co-Authors: Junyi Xiang, Qingyun Huang, Xuewei Lv
    Abstract:

    Abstract Because of its potential to achieve a high recovery rate of vanadium, the mechanical activation pretreatment of vanadium-bearing Converter Slag followed by calcification roasting at low temperature and a two-step leaching process may be a viable alternative to the present roasting and one-step leaching process for vanadium extraction. The object of this study is to enhance the leaching efficiency of vanadium by mechanical activation and two-step leaching methods. The effects of solution acidity, liquid/solid ratio, particle size of the roasted Slag, stirring speed, leaching temperature and time were investigated. The first stage leaching liquor was recycled in order to improve vanadium content in the leaching solution and reduce leaching solution consumption and wastewater discharge. Experimental results showed that approximately 81.8% vanadium was dissolved in the first stage of the leaching process with a solution pH of 2.5, and approximately 8.1% vanadium was dissolved in the second stage of the leaching process with a solution pH of 0. In the first stage, the vanadium leaching efficiency was significantly hindered by long recycle times, though this property also increased the content of vanadium in the leaching solution and greatly decreased the water consumption. In addition, mineralography and microstructures of the solid samples were studied by X-ray powder diffraction (XRD) and scanning electron microscopy (SEM) to help understand the mechanism.

  • multistage utilization process for the gradient recovery of v fe and ti from vanadium bearing Converter Slag
    Journal of Hazardous Materials, 2017
    Co-Authors: Junyi Xiang, Qingyun Huang, Xuewei Lv
    Abstract:

    Abstract A multistage utilization process was developed to fully recover valuable metals from vanadium-bearing Converter Slag and reduce the content of hazardous elements, such as vanadium and chromium, in the tailings. A mechanical activation–calcification roasting–acid leaching process was firstly employed to recover vanadium. This process generated two products, viz. a V-bearing solution accounting for ∼95% V recovery and vanadium tailings with Fe and Ti contents of 31.85% and 8.94%, respectively. Then, based on theoretical calculations and physical measurements, a coal–based direct reduction–magnetic separation process and a hydrochloric acid leaching process were employed for the stepwise recovery of iron and titanium, respectively, from the vanadium tailings. Iron was recovered in the form of high chromium–vanadium iron with 81.53% Fe, 1.31% Cr, and 2.04% V, and titanium was recovered as titanium dioxide pigment with 85–90% yield. Such a comprehensive and clean utilization of vanadium-bearing Converter Slag has great potential for practical application.

  • Effect of Mechanical Activation Treatment on the Recovery of Vanadium from Converter Slag
    Metallurgical and Materials Transactions B-process Metallurgy and Materials Processing Science, 2017
    Co-Authors: Junyi Xiang, Qingyun Huang, Xuewei Lv
    Abstract:

    The high roasting temperature and low leaching efficiency of vanadium from vanadium-bearing Converter Slag are regarded as the main factors significantly influencing the application of calcification roasting–acid leaching processes in the cleaner production of vanadium. In this study, a mechanical activation treatment was performed to enhance the extraction of vanadium from Converter Slag. The enhancement effects obtained from mechanical activation were comprehensively evaluated through indices such as the roasting temperature and leaching efficiency. The effects of mechanical activation time, roasting temperature, leaching temperature, solid to liquid ratio, particle size, and acid concentration on the leaching efficiency were investigated. Microstructure morphology and elemental analyses of the raw materials and leaching residue were also investigated using scanning electron microscopy and energy-dispersive X-ray spectroscopy. The results demonstrated that the mechanical activation significantly decreased the optimum roasting temperature from 1173 K to 1073 K (900 °C to 800 °C) and increased the leaching efficiency from 86.0 to 90.9 pct.

Junyi Xiang - One of the best experts on this subject based on the ideXlab platform.

  • A Multi-step Process for the Cleaner Utilization of Vanadium-Bearing Converter Slag
    Rare Metal Technology 2019, 2019
    Co-Authors: Junyi Xiang, Qingyun Huang, Wei Lv, Mingrui Yang, Kai Hu, Xuewei Lv
    Abstract:

    A multi-step process has been developed for the recovery of metal values from vanadium-bearing Converter Slag. A beneficiation process combined with grinding, sieving and magnetic separation steps was firstly utilized to recover metallic iron from the vanadium-bearing Converter Slag. Then a calcification roasting–acid leaching process was developed to recover vanadium from the vanadium Slag, forming vanadium-bearing solution and vanadium tailings. The vanadium-bearing solution can be further used to recover vanadium, and the vanadium tailings were treated by a carbothermic reduction–magnetic separation process, which generated two products, viz. ferroalloy and titanium concentrate. The ferroalloy can be used as raw materials for the steelmaking process whereas the titanium concentrate can be taken for Ti recovery. The results showed that the majority of iron, vanadium, chromium, and titanium in the vanadium-bearing Converter Slag can be fully recycled in such a comprehensive recovery process.

  • Mineralogical characterisation and magnetic separation of vanadium-bearing Converter Slag.
    Waste Management & Research, 2018
    Co-Authors: Junyi Xiang, Qingyun Huang, Wei Lv, Xuewei Lv
    Abstract:

    : The recycling of metallic iron is commonly the first step to fully use the Converter Slag, which is the biggest waste discharge in the steelmaking process. This study presents a proposed improved process of separating metallic iron from vanadium-bearing Converter Slag more efficiently. The mineralogical and morphological characteristics of the Converter Slag were first investigated, and the results showed that most of the iron was incorporated in the spinel and olivine. Grinding, sieving and magnetic separation were combined to recover metallic iron from the Converter Slag, and yielded approximately 41.5% of iron in which the iron content was as high as 85%, and the non-magnetic concentrate contains 8.56% vanadium with a yield of 95.3% and 8.63% titanium with a yield of 85.3%. The magnetic part can be used as the raw materials in the steel making process, whereas the non-magnetic part can be used as the raw materials for the further extraction of vanadium.

  • extraction of vanadium from Converter Slag by two step sulfuric acid leaching process
    Journal of Cleaner Production, 2018
    Co-Authors: Junyi Xiang, Qingyun Huang, Xuewei Lv
    Abstract:

    Abstract Because of its potential to achieve a high recovery rate of vanadium, the mechanical activation pretreatment of vanadium-bearing Converter Slag followed by calcification roasting at low temperature and a two-step leaching process may be a viable alternative to the present roasting and one-step leaching process for vanadium extraction. The object of this study is to enhance the leaching efficiency of vanadium by mechanical activation and two-step leaching methods. The effects of solution acidity, liquid/solid ratio, particle size of the roasted Slag, stirring speed, leaching temperature and time were investigated. The first stage leaching liquor was recycled in order to improve vanadium content in the leaching solution and reduce leaching solution consumption and wastewater discharge. Experimental results showed that approximately 81.8% vanadium was dissolved in the first stage of the leaching process with a solution pH of 2.5, and approximately 8.1% vanadium was dissolved in the second stage of the leaching process with a solution pH of 0. In the first stage, the vanadium leaching efficiency was significantly hindered by long recycle times, though this property also increased the content of vanadium in the leaching solution and greatly decreased the water consumption. In addition, mineralography and microstructures of the solid samples were studied by X-ray powder diffraction (XRD) and scanning electron microscopy (SEM) to help understand the mechanism.

  • multistage utilization process for the gradient recovery of v fe and ti from vanadium bearing Converter Slag
    Journal of Hazardous Materials, 2017
    Co-Authors: Junyi Xiang, Qingyun Huang, Xuewei Lv
    Abstract:

    Abstract A multistage utilization process was developed to fully recover valuable metals from vanadium-bearing Converter Slag and reduce the content of hazardous elements, such as vanadium and chromium, in the tailings. A mechanical activation–calcification roasting–acid leaching process was firstly employed to recover vanadium. This process generated two products, viz. a V-bearing solution accounting for ∼95% V recovery and vanadium tailings with Fe and Ti contents of 31.85% and 8.94%, respectively. Then, based on theoretical calculations and physical measurements, a coal–based direct reduction–magnetic separation process and a hydrochloric acid leaching process were employed for the stepwise recovery of iron and titanium, respectively, from the vanadium tailings. Iron was recovered in the form of high chromium–vanadium iron with 81.53% Fe, 1.31% Cr, and 2.04% V, and titanium was recovered as titanium dioxide pigment with 85–90% yield. Such a comprehensive and clean utilization of vanadium-bearing Converter Slag has great potential for practical application.

  • Effect of Mechanical Activation Treatment on the Recovery of Vanadium from Converter Slag
    Metallurgical and Materials Transactions B-process Metallurgy and Materials Processing Science, 2017
    Co-Authors: Junyi Xiang, Qingyun Huang, Xuewei Lv
    Abstract:

    The high roasting temperature and low leaching efficiency of vanadium from vanadium-bearing Converter Slag are regarded as the main factors significantly influencing the application of calcification roasting–acid leaching processes in the cleaner production of vanadium. In this study, a mechanical activation treatment was performed to enhance the extraction of vanadium from Converter Slag. The enhancement effects obtained from mechanical activation were comprehensively evaluated through indices such as the roasting temperature and leaching efficiency. The effects of mechanical activation time, roasting temperature, leaching temperature, solid to liquid ratio, particle size, and acid concentration on the leaching efficiency were investigated. Microstructure morphology and elemental analyses of the raw materials and leaching residue were also investigated using scanning electron microscopy and energy-dispersive X-ray spectroscopy. The results demonstrated that the mechanical activation significantly decreased the optimum roasting temperature from 1173 K to 1073 K (900 °C to 800 °C) and increased the leaching efficiency from 86.0 to 90.9 pct.

Qingyun Huang - One of the best experts on this subject based on the ideXlab platform.

  • A Multi-step Process for the Cleaner Utilization of Vanadium-Bearing Converter Slag
    Rare Metal Technology 2019, 2019
    Co-Authors: Junyi Xiang, Qingyun Huang, Wei Lv, Mingrui Yang, Kai Hu, Xuewei Lv
    Abstract:

    A multi-step process has been developed for the recovery of metal values from vanadium-bearing Converter Slag. A beneficiation process combined with grinding, sieving and magnetic separation steps was firstly utilized to recover metallic iron from the vanadium-bearing Converter Slag. Then a calcification roasting–acid leaching process was developed to recover vanadium from the vanadium Slag, forming vanadium-bearing solution and vanadium tailings. The vanadium-bearing solution can be further used to recover vanadium, and the vanadium tailings were treated by a carbothermic reduction–magnetic separation process, which generated two products, viz. ferroalloy and titanium concentrate. The ferroalloy can be used as raw materials for the steelmaking process whereas the titanium concentrate can be taken for Ti recovery. The results showed that the majority of iron, vanadium, chromium, and titanium in the vanadium-bearing Converter Slag can be fully recycled in such a comprehensive recovery process.

  • Mineralogical characterisation and magnetic separation of vanadium-bearing Converter Slag.
    Waste Management & Research, 2018
    Co-Authors: Junyi Xiang, Qingyun Huang, Wei Lv, Xuewei Lv
    Abstract:

    : The recycling of metallic iron is commonly the first step to fully use the Converter Slag, which is the biggest waste discharge in the steelmaking process. This study presents a proposed improved process of separating metallic iron from vanadium-bearing Converter Slag more efficiently. The mineralogical and morphological characteristics of the Converter Slag were first investigated, and the results showed that most of the iron was incorporated in the spinel and olivine. Grinding, sieving and magnetic separation were combined to recover metallic iron from the Converter Slag, and yielded approximately 41.5% of iron in which the iron content was as high as 85%, and the non-magnetic concentrate contains 8.56% vanadium with a yield of 95.3% and 8.63% titanium with a yield of 85.3%. The magnetic part can be used as the raw materials in the steel making process, whereas the non-magnetic part can be used as the raw materials for the further extraction of vanadium.

  • extraction of vanadium from Converter Slag by two step sulfuric acid leaching process
    Journal of Cleaner Production, 2018
    Co-Authors: Junyi Xiang, Qingyun Huang, Xuewei Lv
    Abstract:

    Abstract Because of its potential to achieve a high recovery rate of vanadium, the mechanical activation pretreatment of vanadium-bearing Converter Slag followed by calcification roasting at low temperature and a two-step leaching process may be a viable alternative to the present roasting and one-step leaching process for vanadium extraction. The object of this study is to enhance the leaching efficiency of vanadium by mechanical activation and two-step leaching methods. The effects of solution acidity, liquid/solid ratio, particle size of the roasted Slag, stirring speed, leaching temperature and time were investigated. The first stage leaching liquor was recycled in order to improve vanadium content in the leaching solution and reduce leaching solution consumption and wastewater discharge. Experimental results showed that approximately 81.8% vanadium was dissolved in the first stage of the leaching process with a solution pH of 2.5, and approximately 8.1% vanadium was dissolved in the second stage of the leaching process with a solution pH of 0. In the first stage, the vanadium leaching efficiency was significantly hindered by long recycle times, though this property also increased the content of vanadium in the leaching solution and greatly decreased the water consumption. In addition, mineralography and microstructures of the solid samples were studied by X-ray powder diffraction (XRD) and scanning electron microscopy (SEM) to help understand the mechanism.

  • multistage utilization process for the gradient recovery of v fe and ti from vanadium bearing Converter Slag
    Journal of Hazardous Materials, 2017
    Co-Authors: Junyi Xiang, Qingyun Huang, Xuewei Lv
    Abstract:

    Abstract A multistage utilization process was developed to fully recover valuable metals from vanadium-bearing Converter Slag and reduce the content of hazardous elements, such as vanadium and chromium, in the tailings. A mechanical activation–calcification roasting–acid leaching process was firstly employed to recover vanadium. This process generated two products, viz. a V-bearing solution accounting for ∼95% V recovery and vanadium tailings with Fe and Ti contents of 31.85% and 8.94%, respectively. Then, based on theoretical calculations and physical measurements, a coal–based direct reduction–magnetic separation process and a hydrochloric acid leaching process were employed for the stepwise recovery of iron and titanium, respectively, from the vanadium tailings. Iron was recovered in the form of high chromium–vanadium iron with 81.53% Fe, 1.31% Cr, and 2.04% V, and titanium was recovered as titanium dioxide pigment with 85–90% yield. Such a comprehensive and clean utilization of vanadium-bearing Converter Slag has great potential for practical application.

  • Effect of Mechanical Activation Treatment on the Recovery of Vanadium from Converter Slag
    Metallurgical and Materials Transactions B-process Metallurgy and Materials Processing Science, 2017
    Co-Authors: Junyi Xiang, Qingyun Huang, Xuewei Lv
    Abstract:

    The high roasting temperature and low leaching efficiency of vanadium from vanadium-bearing Converter Slag are regarded as the main factors significantly influencing the application of calcification roasting–acid leaching processes in the cleaner production of vanadium. In this study, a mechanical activation treatment was performed to enhance the extraction of vanadium from Converter Slag. The enhancement effects obtained from mechanical activation were comprehensively evaluated through indices such as the roasting temperature and leaching efficiency. The effects of mechanical activation time, roasting temperature, leaching temperature, solid to liquid ratio, particle size, and acid concentration on the leaching efficiency were investigated. Microstructure morphology and elemental analyses of the raw materials and leaching residue were also investigated using scanning electron microscopy and energy-dispersive X-ray spectroscopy. The results demonstrated that the mechanical activation significantly decreased the optimum roasting temperature from 1173 K to 1073 K (900 °C to 800 °C) and increased the leaching efficiency from 86.0 to 90.9 pct.

Fereshteh Rashchi - One of the best experts on this subject based on the ideXlab platform.

  • Optimization and dissolution kinetics of vanadium recovery from LD Converter Slag in alkaline media
    Russian Journal of Non-Ferrous Metals, 2016
    Co-Authors: S M J Mirazimi, Fereshteh Rashchi, E. Vahidi, N. Mostoufi
    Abstract:

    Alkaline roasting-alkaline leaching process was used to recover vanadium from LD (Linz Donawitz) Converter Slag. The independent leaching parameters investigated were liquid to solid ratio (L/S) (10–20 mL/g), temperature (40–60°C), NaOH concentration (1.0–3.0 M), and time (60–120 minutes). Response surface methodology (RSM) was utilized to optimize the leaching parameters and as a result, the most influencing parameter was found to be liquid to solid ratio. Based on the results, the optimum recovery condition (approx. 99%) was obtained with L/S ratio of 20, temperature of 40°C, NaOH concentration of 3.0M, and leaching time of 100 minutes, respectively. Furthermore, the kinetics of alkaline leaching process was investigated using shrinking core model (SCM) equations. It was found that the rate of vanadium leaching is controlled by a mixed controlling mechanism which is comprised of chemical reaction and diffusion through the solid product layer.

  • vanadium removal from ld Converter Slag using bacteria and fungi
    Journal of Environmental Management, 2015
    Co-Authors: S M J Mirazimi, Z Abbasalipour, Fereshteh Rashchi
    Abstract:

    Abstract Removal of vanadium from Linz-Donawits (LD) Converter Slag was investigated by means of three different species of microbial systems: Acidithiobacillus thiooxidans (autotrophic bacteria), Pseudomonas putida (heterotrophic bacteria) and Aspergillus niger (fungi). The bioleaching process was carried out in both one-step and two-step process and the leaching efficiencies in both cases were compared. Formation of inorganic and organic acids during the leaching process caused mobilization of vanadium. In order to reduce toxic effects of the metal species on the above mentioned microorganisms, a prolonged adaptation process was performed. Both bacteria, A. thiooxidans and P. putida were able to remove more than 90% of vanadium at Slag concentrations of 1–5 g L−1 after 15 days. Also, the maximum achievable vanadium removal in the fungal system was approximately 92% at a Slag concentration of 1 g L−1 after 22 days.

  • a new approach for direct leaching of vanadium from ld Converter Slag
    Chemical Engineering Research & Design, 2015
    Co-Authors: S M J Mirazimi, Fereshteh Rashchi, M Saba
    Abstract:

    Abstract Direct acid leaching process was used to recover vanadium from Linz Donawitz (LD) Converter Slag. The leaching parameters were studied to obtain conditions that vanadium can be leached without using a pyro metallurgical step since the roasting process requires high energy consumption. The independent leaching factors investigated were liquid to solid ratio (L/S) (10–20 mL/g), temperature (40–70 °C), acid concentration (1.5–3.0 M), stirring rate (500–700 rpm) and time (60–120 min). Response surface methodology (RSM) was used to optimize the process parameters. The most influencing parameter was found to be temperature and the less effective was acid concentration. It was shown that the optimum condition for recovery of ca. 98% can be obtained at L/S ratio of 17.52, temperature of 70 °C, acid concentration of 2.82 M and leaching time of 120 min. The shrinking core model (SCM) was used to describe the kinetics of the Slag acid leaching. A constrained multi-linear regression analysis using the least square technique was used to determine the rate controlling mechanism. This technique takes into account all three possible rate controlling mechanisms for leaching processes (i.e., chemical reaction, diffusion through product layer and liquid film mass transfer) simultaneously. Results of kinetic study by this method shown that the rate of the leaching is controlled by chemical reaction at low temperature whereas it is controlled by diffusion through the solid product layer in a long time, i.e., after 60 min from the start of the leaching process, at high temperature.

  • vanadium removal from roasted ld Converter Slag optimization of parameters by response surface methodology rsm
    Separation and Purification Technology, 2013
    Co-Authors: S M J Mirazimi, Fereshteh Rashchi, M Saba
    Abstract:

    Abstract Alkaline roasting-sulfuric acid leaching process was used to remove vanadium from LD (Linz Donawitz) Converter Slag. Leaching parameters were investigated and optimized in order to maximize the recovery of vanadium as the vanadium content in the Slag is low. The independent leaching factors investigated were liquid to solid ratio (L/S) (10–20 mL/g), temperature (40–70 °C), sulfuric acid concentration (1.5–3.0 M), stirring rate (500–700 rpm) and time (60–120 min). Response surface methodology (RSM) was used to optimize the process parameters. To choose the best model for describing the leaching process, Box–Cox power transformation technique was used which in turn was used to normalize the data. The most influencing parameter was found to be L/S and the less effective was stirring rate as well. Based on the results, optimum removal condition (approx. 96%) according to process parameters was obtained with L/S ratio of (19.99), temperature of (70 °C), sulfuric acid concentration of 2.05 M, rpm of (558) and leaching time of (60 min), respectively.

  • leaching of vanadium from ld Converter Slag using sulfuric acid
    Hydrometallurgy, 2010
    Co-Authors: M Aarabikarasgani, Fereshteh Rashchi, N. Mostoufi, E. Vahidi
    Abstract:

    Abstract In order to extract vanadium from LD (Linz–Donawitz) Converter Slag of steelmaking plant, an alkaline roasting–acid leaching study was carried out and the effect of different parameters on the kinetics of vanadium dissolution was determined. The leaching residue was characterized by XRD, XRF and SEM/EDX analyzer. The maximum vanadium recovery of ca. 95% was achieved at the optimum leaching condition of 70 °C, S/L: 1/15, acid concentration: 3 M and leaching time: 150 min. It was shown that particle size has a significant effect on the dissolution of vanadium and maximum extraction was achieved at the finest size of below 0.850 mm. Dissolution of vanadium in sulfuric acid showed that there are two stages in the kinetics of leaching. In the first 15 min, a sharp increase in the amount of vanadium extracted was observed and at longer times, leaching became slower. Shrinking core model (SCM) was used to describe the kinetics of the Slag acid leaching. SCM equations were modified to represent the long time leaching process in which the initial recovery of vanadium (at the beginning of long term period) is not zero. It was found that the kinetics of leaching at low temperature is controlled by chemical reaction for both short and long leaching periods. Rate of leaching is controlled by solid product diffusion regime at high temperature.

S M J Mirazimi - One of the best experts on this subject based on the ideXlab platform.

  • Optimization and dissolution kinetics of vanadium recovery from LD Converter Slag in alkaline media
    Russian Journal of Non-Ferrous Metals, 2016
    Co-Authors: S M J Mirazimi, Fereshteh Rashchi, E. Vahidi, N. Mostoufi
    Abstract:

    Alkaline roasting-alkaline leaching process was used to recover vanadium from LD (Linz Donawitz) Converter Slag. The independent leaching parameters investigated were liquid to solid ratio (L/S) (10–20 mL/g), temperature (40–60°C), NaOH concentration (1.0–3.0 M), and time (60–120 minutes). Response surface methodology (RSM) was utilized to optimize the leaching parameters and as a result, the most influencing parameter was found to be liquid to solid ratio. Based on the results, the optimum recovery condition (approx. 99%) was obtained with L/S ratio of 20, temperature of 40°C, NaOH concentration of 3.0M, and leaching time of 100 minutes, respectively. Furthermore, the kinetics of alkaline leaching process was investigated using shrinking core model (SCM) equations. It was found that the rate of vanadium leaching is controlled by a mixed controlling mechanism which is comprised of chemical reaction and diffusion through the solid product layer.

  • vanadium removal from ld Converter Slag using bacteria and fungi
    Journal of Environmental Management, 2015
    Co-Authors: S M J Mirazimi, Z Abbasalipour, Fereshteh Rashchi
    Abstract:

    Abstract Removal of vanadium from Linz-Donawits (LD) Converter Slag was investigated by means of three different species of microbial systems: Acidithiobacillus thiooxidans (autotrophic bacteria), Pseudomonas putida (heterotrophic bacteria) and Aspergillus niger (fungi). The bioleaching process was carried out in both one-step and two-step process and the leaching efficiencies in both cases were compared. Formation of inorganic and organic acids during the leaching process caused mobilization of vanadium. In order to reduce toxic effects of the metal species on the above mentioned microorganisms, a prolonged adaptation process was performed. Both bacteria, A. thiooxidans and P. putida were able to remove more than 90% of vanadium at Slag concentrations of 1–5 g L−1 after 15 days. Also, the maximum achievable vanadium removal in the fungal system was approximately 92% at a Slag concentration of 1 g L−1 after 22 days.

  • a new approach for direct leaching of vanadium from ld Converter Slag
    Chemical Engineering Research & Design, 2015
    Co-Authors: S M J Mirazimi, Fereshteh Rashchi, M Saba
    Abstract:

    Abstract Direct acid leaching process was used to recover vanadium from Linz Donawitz (LD) Converter Slag. The leaching parameters were studied to obtain conditions that vanadium can be leached without using a pyro metallurgical step since the roasting process requires high energy consumption. The independent leaching factors investigated were liquid to solid ratio (L/S) (10–20 mL/g), temperature (40–70 °C), acid concentration (1.5–3.0 M), stirring rate (500–700 rpm) and time (60–120 min). Response surface methodology (RSM) was used to optimize the process parameters. The most influencing parameter was found to be temperature and the less effective was acid concentration. It was shown that the optimum condition for recovery of ca. 98% can be obtained at L/S ratio of 17.52, temperature of 70 °C, acid concentration of 2.82 M and leaching time of 120 min. The shrinking core model (SCM) was used to describe the kinetics of the Slag acid leaching. A constrained multi-linear regression analysis using the least square technique was used to determine the rate controlling mechanism. This technique takes into account all three possible rate controlling mechanisms for leaching processes (i.e., chemical reaction, diffusion through product layer and liquid film mass transfer) simultaneously. Results of kinetic study by this method shown that the rate of the leaching is controlled by chemical reaction at low temperature whereas it is controlled by diffusion through the solid product layer in a long time, i.e., after 60 min from the start of the leaching process, at high temperature.

  • vanadium removal from roasted ld Converter Slag optimization of parameters by response surface methodology rsm
    Separation and Purification Technology, 2013
    Co-Authors: S M J Mirazimi, Fereshteh Rashchi, M Saba
    Abstract:

    Abstract Alkaline roasting-sulfuric acid leaching process was used to remove vanadium from LD (Linz Donawitz) Converter Slag. Leaching parameters were investigated and optimized in order to maximize the recovery of vanadium as the vanadium content in the Slag is low. The independent leaching factors investigated were liquid to solid ratio (L/S) (10–20 mL/g), temperature (40–70 °C), sulfuric acid concentration (1.5–3.0 M), stirring rate (500–700 rpm) and time (60–120 min). Response surface methodology (RSM) was used to optimize the process parameters. To choose the best model for describing the leaching process, Box–Cox power transformation technique was used which in turn was used to normalize the data. The most influencing parameter was found to be L/S and the less effective was stirring rate as well. Based on the results, optimum removal condition (approx. 96%) according to process parameters was obtained with L/S ratio of (19.99), temperature of (70 °C), sulfuric acid concentration of 2.05 M, rpm of (558) and leaching time of (60 min), respectively.