The Experts below are selected from a list of 16953 Experts worldwide ranked by ideXlab platform
M Saba - One of the best experts on this subject based on the ideXlab platform.
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a new approach for direct leaching of vanadium from ld converter slag
Chemical Engineering Research & Design, 2015Co-Authors: S M J Mirazimi, Fereshteh Rashchi, M SabaAbstract: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.
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vanadium removal from roasted ld converter slag optimization of Parameters by response surface methodology rsm
Separation and Purification Technology, 2013Co-Authors: S M J Mirazimi, Fereshteh Rashchi, M SabaAbstract: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.
S M J Mirazimi - One of the best experts on this subject based on the ideXlab platform.
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Optimization and dissolution kinetics of vanadium recovery from LD converter slag in alkaline media
Russian Journal of Non-Ferrous Metals, 2016Co-Authors: S M J Mirazimi, Fereshteh Rashchi, Ehsan Vahidi, Navid MostoufiAbstract: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.
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a new approach for direct leaching of vanadium from ld converter slag
Chemical Engineering Research & Design, 2015Co-Authors: S M J Mirazimi, Fereshteh Rashchi, M SabaAbstract: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.
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vanadium removal from roasted ld converter slag optimization of Parameters by response surface methodology rsm
Separation and Purification Technology, 2013Co-Authors: S M J Mirazimi, Fereshteh Rashchi, M SabaAbstract: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.
Karine Anselme - One of the best experts on this subject based on the ideXlab platform.
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Statistical approach of chemistry and topography effect on human osteoblast adhesion
Journal of Biomedical Materials Research Part A, 2010Co-Authors: Sylvain Giljean, Arnaud Ponche, Maxence Bigerelle, Karine AnselmeAbstract:Our objective in this work was to determine statistically the relative influence of surface topography and surface chemistry of metallic substrates on long‐term adhesion of human bone cell quantified by the adhesion power (AP). Pure titanium, titanium alloy, and stainless steel substrates were processed with electro‐erosion, sandblasting, or polishing giving various morphologies and amplitudes. The surface chemistry was characterized by X‐ray photoelectron spectroscopy (XPS) associated with an extensive analysis of surface topography. The statistical analysis demonstrated that the effect on AP of the material composition was not significant. More, no correlation was found between AP and the surface element concentrations determined by XPS demonstrating that the surface chemistry was not an Influencing Parameter for long‐term adhesion. In the same way, the roughness amplitude, independently of the process, had no influence on AP, meaning that roughness amplitude is not an intrinsic Parameter of long‐term adhesion. On the contrary, the elaboration process alone had a significant effect on AP. For a same surface elaboration process, the number of inflexion points, or G Parameter, was the most pertinent roughness Parameter for describing the topography influence on long‐term adhesion. Thus, more the inflexion points, more the discontinuities, higher the long‐term adhesion. © 2010 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2010
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Improvement in the morphology of Ti-based surfaces: a new process to increase in vitro human osteoblast response
Biomaterials, 2002Co-Authors: Maxence Bigerelle, Karine Anselme, B. Noël, I. Ruderman, P. Hardouin, A. IostAbstract:Surface roughness has been shown to be an Influencing Parameter for cell response. In this experience we attempted to compare the effect of roughness organization of Ti6Al4V or pure titanium substrates on human osteoblast (hOB) response (proliferation, adhesion). Surface roughness was extensively analyzed at scales above the cell size (macro-roughness) or below the cell size (micro-roughness) by calculation of relevant classic amplitude Parameters (Ra, Rt) and original frequency Parameters (Order, Delta). We developed a new process to prepare isotropic surfaces (electro-erosion), which were compared to isotropic surfaces obtained by polishing and anisotropic surfaces obtained by machine-tooling. The hOB response on electro-eroded (EE) Ti6Al4V surfaces or pure titanium (Ti) surfaces was largely increased when compared to polished or machine-tooled surfaces after 21 days of culture. Moreover, the polygonal morphology of hOB on these EE surfaces was very close to the aspects of hOB in vivo on human bone trabeculae. By a complete description of the surface topography of EE surfaces, we concluded that when the topography was considered below the cell scale, hOB appreciated their isotropic smooth aspect, although when the topography was considered above the cell scale they appreciated their rough isotropic ‘landscape’ formed by many ‘bowl-like nests’ favouring cell adhesion and growth. Electro-erosion is a promising method for preparation of bone implant surfaces, as it could easily be applied to preparation of most biomaterials with complex geometries.
Erion Luga - One of the best experts on this subject based on the ideXlab platform.
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very high strength 120 mpa class f fly ash geopolymer mortar activated at different naoh amount heat curing temperature and heat curing duration
Construction and Building Materials, 2015Co-Authors: Cengiz Duran Atis, Ela Bahsude Gorur, Okan Karahan, Cahit Bilim, Serhan Ilkentapar, Erion LugaAbstract:Abstract In this laboratory work, high compressive and flexural tensile strength of alkali activated fly ash geopolymer mortars were presented. Class F fly ash was used throughout the study. NaOH was used as alkali medium that provides high pH value. Also, the factors Influencing the compressive and flexural tensile strength were investigated. A total of 216 fly ash geopolymer mortar samples were prepared. Heat curing temperature, heat curing duration and alkali (Na) concentration were chosen as the Influencing Parameters of strengths. Mortar mixture Parameters were 3 and 1/3 for sand–binder ratio, and water–binder ratio, respectively. Na concentrations of the mortar mixtures were changed from 4% to 20% with 2% increment step. Heat curing temperatures were changed from 45 to 115 °C with 10 °C increment step. Heat curing durations were chosen as 24, 48 and 72 h. For each combination of Influencing Parameter, three prismatic specimens with 40 mm × 40 mm × 160 mm dimensions were prepared using a three-cell mortar cast. After heat curing period in a laboratory oven, the samples were left to cool down to room temperature, then compressive and flexural strengths were measured as described in its respective standard. Very high compressive and flexural tensile strength obtained, which were as high as 120 and 15 MPa respectively.
Maxence Bigerelle - One of the best experts on this subject based on the ideXlab platform.
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Statistical approach of chemistry and topography effect on human osteoblast adhesion
Journal of Biomedical Materials Research Part A, 2010Co-Authors: Sylvain Giljean, Arnaud Ponche, Maxence Bigerelle, Karine AnselmeAbstract:Our objective in this work was to determine statistically the relative influence of surface topography and surface chemistry of metallic substrates on long‐term adhesion of human bone cell quantified by the adhesion power (AP). Pure titanium, titanium alloy, and stainless steel substrates were processed with electro‐erosion, sandblasting, or polishing giving various morphologies and amplitudes. The surface chemistry was characterized by X‐ray photoelectron spectroscopy (XPS) associated with an extensive analysis of surface topography. The statistical analysis demonstrated that the effect on AP of the material composition was not significant. More, no correlation was found between AP and the surface element concentrations determined by XPS demonstrating that the surface chemistry was not an Influencing Parameter for long‐term adhesion. In the same way, the roughness amplitude, independently of the process, had no influence on AP, meaning that roughness amplitude is not an intrinsic Parameter of long‐term adhesion. On the contrary, the elaboration process alone had a significant effect on AP. For a same surface elaboration process, the number of inflexion points, or G Parameter, was the most pertinent roughness Parameter for describing the topography influence on long‐term adhesion. Thus, more the inflexion points, more the discontinuities, higher the long‐term adhesion. © 2010 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2010
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Improvement in the morphology of Ti-based surfaces: a new process to increase in vitro human osteoblast response
Biomaterials, 2002Co-Authors: Maxence Bigerelle, Karine Anselme, B. Noël, I. Ruderman, P. Hardouin, A. IostAbstract:Surface roughness has been shown to be an Influencing Parameter for cell response. In this experience we attempted to compare the effect of roughness organization of Ti6Al4V or pure titanium substrates on human osteoblast (hOB) response (proliferation, adhesion). Surface roughness was extensively analyzed at scales above the cell size (macro-roughness) or below the cell size (micro-roughness) by calculation of relevant classic amplitude Parameters (Ra, Rt) and original frequency Parameters (Order, Delta). We developed a new process to prepare isotropic surfaces (electro-erosion), which were compared to isotropic surfaces obtained by polishing and anisotropic surfaces obtained by machine-tooling. The hOB response on electro-eroded (EE) Ti6Al4V surfaces or pure titanium (Ti) surfaces was largely increased when compared to polished or machine-tooled surfaces after 21 days of culture. Moreover, the polygonal morphology of hOB on these EE surfaces was very close to the aspects of hOB in vivo on human bone trabeculae. By a complete description of the surface topography of EE surfaces, we concluded that when the topography was considered below the cell scale, hOB appreciated their isotropic smooth aspect, although when the topography was considered above the cell scale they appreciated their rough isotropic ‘landscape’ formed by many ‘bowl-like nests’ favouring cell adhesion and growth. Electro-erosion is a promising method for preparation of bone implant surfaces, as it could easily be applied to preparation of most biomaterials with complex geometries.