Platinum-modified-?NiAl is a bond coat (BC) material for thermal barrier coatings (TBCs) applications applied on aero-engine hardware to reduce their surface temperatures. However, it is desirable to minimize its production and material costs by the low-cost alternatives of similar performance. As, it has been acknowledged that the small concentration of the reactive elements (REs), such as Zr, Hf, and Y, could tremendously enhance the oxide adhesion even in some cases better than Pt modified counterparts. The present study aims to design and fabricate the Zr-modified-?NiAl bond coat on CMSX-4 superalloy using an aluminizing method. Moreover, the study focuses on the development of a systematic understanding of underlying mechanisms behind the beneficial effects of REs. Initially, three sets of BCs were prepared: Zr-free ?NiAl (undoped), Al and Zr co-deposited in a single-step process (1SP), and Zr and Al, which were individually deposited in two processing steps (2SP): zirconizing and aluminizing. Such three sets of BCs help to understand the processing, as well as Zr and Al effects on scale adhesion. In particular, 1SP/2SP BCs showed uniformity of Zr in the form of precipitates and networks that caused hardness enhancement. All BCs were isothermally oxidized at 1150oC for 100 hours wherein 2SP revealed the best spallation resistance, microstructural stability and its Zr-oxide pegs were extended to substrates. In addition to the Zr effect, BC Al content was found to affect the oxide adhesion equally. Under identical Zr contents (of 1SP and 2SP = 1at %), the higher Al showed the better spallation resistance while lower Al caused the inverse effect of Zr owing to its reactive nature that is termed as over doping. Moreover, it has been established that over-doping either local or into entire BC, accelerates the Al depletion that destabilizes the ?NiAl into ??-Ni3Al phase. An extensive discussion is presented in the light of observed results.
{"title":"Processing, characterisation and oxidation resistance of βNiAl bond coat: Al and Zr effects","authors":"A. Chandio, A. Shaikh, W. Salman, H. A. Ahmed","doi":"10.2298/JMMB201108026C","DOIUrl":"https://doi.org/10.2298/JMMB201108026C","url":null,"abstract":"Platinum-modified-?NiAl is a bond coat (BC) material for thermal barrier coatings (TBCs) applications applied on aero-engine hardware to reduce their surface temperatures. However, it is desirable to minimize its production and material costs by the low-cost alternatives of similar performance. As, it has been acknowledged that the small concentration of the reactive elements (REs), such as Zr, Hf, and Y, could tremendously enhance the oxide adhesion even in some cases better than Pt modified counterparts. The present study aims to design and fabricate the Zr-modified-?NiAl bond coat on CMSX-4 superalloy using an aluminizing method. Moreover, the study focuses on the development of a systematic understanding of underlying mechanisms behind the beneficial effects of REs. Initially, three sets of BCs were prepared: Zr-free ?NiAl (undoped), Al and Zr co-deposited in a single-step process (1SP), and Zr and Al, which were individually deposited in two processing steps (2SP): zirconizing and aluminizing. Such three sets of BCs help to understand the processing, as well as Zr and Al effects on scale adhesion. In particular, 1SP/2SP BCs showed uniformity of Zr in the form of precipitates and networks that caused hardness enhancement. All BCs were isothermally oxidized at 1150oC for 100 hours wherein 2SP revealed the best spallation resistance, microstructural stability and its Zr-oxide pegs were extended to substrates. In addition to the Zr effect, BC Al content was found to affect the oxide adhesion equally. Under identical Zr contents (of 1SP and 2SP = 1at %), the higher Al showed the better spallation resistance while lower Al caused the inverse effect of Zr owing to its reactive nature that is termed as over doping. Moreover, it has been established that over-doping either local or into entire BC, accelerates the Al depletion that destabilizes the ?NiAl into ??-Ni3Al phase. An extensive discussion is presented in the light of observed results.","PeriodicalId":51090,"journal":{"name":"Journal of Mining and Metallurgy Section B-Metallurgy","volume":"60 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77366664","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
J. Guo, D. Fu, Jibiao Han, Zonghui Ji, Y.-S. Wang, T.-A. Zhang
At present, the production of magnesium is mainly carried out semi-continuously with ferrosilicon as reducing agent under high temperature and high vacuum. In order to continuously produce magnesium, anew method of extracting magnesium from low-grade magnesite and calcium carbonate by silicothermal method in flowing inert gas was proposed. The effects of calcium fluoride(CaF2)on decomposition rate, decomposition kinetics, reduction rate of magnesia and crystal type of dicalcium silicate in reduction slag were investigated in the paper. The experimental results showed that calcium fluoride could accelerate the decomposition of carbonate, and had no side effect on the calcined products. In addition, the analysis results of DTA curves showed that calcium fluoridecould reduce the decomposition reaction activation energy and the reaction temperature of carbonatein the prefabricated pellets. The results of reduction experiments showed that proper calcium fluoridecould promote the reduction rate of magnesia, and in the temperature range of 1250? ~ 1350?, with same timeframe, the corresponding calcium fluoride contents were5%, 3% and 1% respectively when the reduction rate reached the maximum. Excessive calcium fluoride could reduce the reduction rate of magnesia, but it couldpromote the transformation of dicalcium silicate to ? phase in the reduction slag.
{"title":"The effect of calcium fluoride on extracting magnesium from magnesite and calcium carbonate by silicothermal reduction in flowing argon","authors":"J. Guo, D. Fu, Jibiao Han, Zonghui Ji, Y.-S. Wang, T.-A. Zhang","doi":"10.2298/jmmb210318045g","DOIUrl":"https://doi.org/10.2298/jmmb210318045g","url":null,"abstract":"At present, the production of magnesium is mainly carried out semi-continuously with ferrosilicon as reducing agent under high temperature and high vacuum. In order to continuously produce magnesium, anew method of extracting magnesium from low-grade magnesite and calcium carbonate by silicothermal method in flowing inert gas was proposed. The effects of calcium fluoride(CaF2)on decomposition rate, decomposition kinetics, reduction rate of magnesia and crystal type of dicalcium silicate in reduction slag were investigated in the paper. The experimental results showed that calcium fluoride could accelerate the decomposition of carbonate, and had no side effect on the calcined products. In addition, the analysis results of DTA curves showed that calcium fluoridecould reduce the decomposition reaction activation energy and the reaction temperature of carbonatein the prefabricated pellets. The results of reduction experiments showed that proper calcium fluoridecould promote the reduction rate of magnesia, and in the temperature range of 1250? ~ 1350?, with same timeframe, the corresponding calcium fluoride contents were5%, 3% and 1% respectively when the reduction rate reached the maximum. Excessive calcium fluoride could reduce the reduction rate of magnesia, but it couldpromote the transformation of dicalcium silicate to ? phase in the reduction slag.","PeriodicalId":51090,"journal":{"name":"Journal of Mining and Metallurgy Section B-Metallurgy","volume":"26 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85907610","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Q. Gao, J. Wang, Yong Du, S. Shang, Zi-kui Liu, Y. J. Liu
Atomic structure, diffusivity and viscosity of Al1-xMgx (x=0, 0.0039, 0.1172, 0.9180, 0.9961, 1)melts at 875, 1000, 1125, and 1250K were investigated by the ab initio molecular dynamics (AIMD) simulations. The simulated results are compared with available experimental and calculated data in the literature with reasonable agreements. Considering the results of pair correlation function g(r), it can be observed that Mg atoms in Al0.8828Mg0.1172 melt aggregate more obviously at 1000 and 1250K. For Al0.0820Mg0.9180, Al atom segregation is more obvious at 875 and 1000K. The tracer diffusion coefficients of Al or Mg in Al1-xMgx (x=0.1172, 0.9180) melts, and interdiffusion coefficients of Al0.8828Mg0.1172 and Al0.0820Mg0.9180 melts are all close to the self-diffusion coefficients of Al or Mg. With the increasing temperature, the diffusivity increases linearly. In dilute melts, the tracer diffusion coefficients of solute atom and the interdiffusion coefficients increase nonlinearly with the increasing temperature. For Al0.8828Mg0.1172 and Al0.0820Mg0.9180 melts, the viscosities ? are comparatively higher than pure melts. The viscosities of all melts decrease with the increasing temperature, then increase at 1250K. The results obtained in the present work provide an insight into the design of Al and Mg alloys.
{"title":"Atomic structure, diffusivity and viscosity of Al1-xMgx melts from ab initio molecular dynamics simulations","authors":"Q. Gao, J. Wang, Yong Du, S. Shang, Zi-kui Liu, Y. J. Liu","doi":"10.2298/jmmb200807037g","DOIUrl":"https://doi.org/10.2298/jmmb200807037g","url":null,"abstract":"Atomic structure, diffusivity and viscosity of Al1-xMgx (x=0, 0.0039, 0.1172, 0.9180, 0.9961, 1)melts at 875, 1000, 1125, and 1250K were investigated by the ab initio molecular dynamics (AIMD) simulations. The simulated results are compared with available experimental and calculated data in the literature with reasonable agreements. Considering the results of pair correlation function g(r), it can be observed that Mg atoms in Al0.8828Mg0.1172 melt aggregate more obviously at 1000 and 1250K. For Al0.0820Mg0.9180, Al atom segregation is more obvious at 875 and 1000K. The tracer diffusion coefficients of Al or Mg in Al1-xMgx (x=0.1172, 0.9180) melts, and interdiffusion coefficients of Al0.8828Mg0.1172 and Al0.0820Mg0.9180 melts are all close to the self-diffusion coefficients of Al or Mg. With the increasing temperature, the diffusivity increases linearly. In dilute melts, the tracer diffusion coefficients of solute atom and the interdiffusion coefficients increase nonlinearly with the increasing temperature. For Al0.8828Mg0.1172 and Al0.0820Mg0.9180 melts, the viscosities ? are comparatively higher than pure melts. The viscosities of all melts decrease with the increasing temperature, then increase at 1250K. The results obtained in the present work provide an insight into the design of Al and Mg alloys.","PeriodicalId":51090,"journal":{"name":"Journal of Mining and Metallurgy Section B-Metallurgy","volume":"11 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84933464","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A. Amdur, E. Selivanov, S. Fedorov, V. Pavlov, S. Krasikov
Copper-nickel sulfide ores are one of the main sources of platinum. One of the ways to extract precious metals from such ores involves melting of a concentrate in electric ore smelting furnaces, where the melt is divided into matte and slag. Platinum is generally concentrated in matte; however, some its part remains in the slag, thus leading to metal losses. In order to reduce platinum losses, the forms of platinum in these phases should be studied. It was found that during the melting of this ore, iron, nickel, and copper are reduced. The mineral composition of matte has been studied. Platinum in matte is present in the form of intermetallics with Fe and Ni. The PtFe intermetallic is a dispersed needle formation with a length of 20 to 500 ?m and a thickness of up to 10 ?m. The size effect is revealed: the content of platinum in the PtFe intermetallic decreases with decreasing the thickness of needle formations. The decreases in the content of platinum in dispersed needle formations can be explained by an increase in the thermodynamic activity and changing properties of the dispersed substance and a corresponding increase in solubility. It was found that matte drops, together with their associated platinum-containing particles of no more than 5-7 ?m in size, were carried into the slag by gas bubbles using flotation. The conditions for the rise of a matte drop, together with a bubble in the slag, consist in the fact that the adhesive force of the drop with the bubble and the buoyancy force acting on the bubble must be greater than the gravity of the drop.
{"title":"Behavior of platinum in the system of the matte-slag in the processing of copper-nickel ores","authors":"A. Amdur, E. Selivanov, S. Fedorov, V. Pavlov, S. Krasikov","doi":"10.2298/JMMB200312016A","DOIUrl":"https://doi.org/10.2298/JMMB200312016A","url":null,"abstract":"Copper-nickel sulfide ores are one of the main sources of platinum. One of the ways to extract precious metals from such ores involves melting of a concentrate in electric ore smelting furnaces, where the melt is divided into matte and slag. Platinum is generally concentrated in matte; however, some its part remains in the slag, thus leading to metal losses. In order to reduce platinum losses, the forms of platinum in these phases should be studied. It was found that during the melting of this ore, iron, nickel, and copper are reduced. The mineral composition of matte has been studied. Platinum in matte is present in the form of intermetallics with Fe and Ni. The PtFe intermetallic is a dispersed needle formation with a length of 20 to 500 ?m and a thickness of up to 10 ?m. The size effect is revealed: the content of platinum in the PtFe intermetallic decreases with decreasing the thickness of needle formations. The decreases in the content of platinum in dispersed needle formations can be explained by an increase in the thermodynamic activity and changing properties of the dispersed substance and a corresponding increase in solubility. It was found that matte drops, together with their associated platinum-containing particles of no more than 5-7 ?m in size, were carried into the slag by gas bubbles using flotation. The conditions for the rise of a matte drop, together with a bubble in the slag, consist in the fact that the adhesive force of the drop with the bubble and the buoyancy force acting on the bubble must be greater than the gravity of the drop.","PeriodicalId":51090,"journal":{"name":"Journal of Mining and Metallurgy Section B-Metallurgy","volume":"36 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76720798","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Mechanical soft reduction (MSR) is an effective method for elimination of the centerline segregation and porosity of the continuous casting steel slab, and the reduction amount is a key parameter that determines whether the MSR could be applied successfully. In the present work, a 2D heat transfer model was developed for predicting the non-uniform solidification of the wide-thick slab. The measured shell thickness by nail shooting experiment and the measured slab surface temperature by infrared camera were applied to validate the 2D heat transfer model. A new calculation method of theoretical reduction amount that could consider the influence of non-uniform solidification of the wide-thick slab was then derived. Based on the predicted temperature field by the 2D heat transfer model and the newly-proposed calculation method, the required theoretical reduction amount and reduction gradient/rate for the wide-thick slab were calculated and discussed. The difference between the newly-proposed method and the previous method, the influence of the casting speed and slab thickness on the required theoretical reduction amount and reduction gradient/rate were also investigated.
{"title":"A new method for determination of the theoretical reduction amount for wide-thick slab during the mechanical reduction process","authors":"C. Wu, J. Zeng, G.-R. Wu, X. Xie, M. Zhang","doi":"10.2298/JMMB200622010W","DOIUrl":"https://doi.org/10.2298/JMMB200622010W","url":null,"abstract":"Mechanical soft reduction (MSR) is an effective method for elimination of the centerline segregation and porosity of the continuous casting steel slab, and the reduction amount is a key parameter that determines whether the MSR could be applied successfully. In the present work, a 2D heat transfer model was developed for predicting the non-uniform solidification of the wide-thick slab. The measured shell thickness by nail shooting experiment and the measured slab surface temperature by infrared camera were applied to validate the 2D heat transfer model. A new calculation method of theoretical reduction amount that could consider the influence of non-uniform solidification of the wide-thick slab was then derived. Based on the predicted temperature field by the 2D heat transfer model and the newly-proposed calculation method, the required theoretical reduction amount and reduction gradient/rate for the wide-thick slab were calculated and discussed. The difference between the newly-proposed method and the previous method, the influence of the casting speed and slab thickness on the required theoretical reduction amount and reduction gradient/rate were also investigated.","PeriodicalId":51090,"journal":{"name":"Journal of Mining and Metallurgy Section B-Metallurgy","volume":"17 1","pages":"125-136"},"PeriodicalIF":1.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88766554","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
D. Wei, Xiaoyong Zhou, Fengkun Li, M. Li, Shuqin Li, Pingze Zhang
To improve the wear resistance of ?-TiAl alloy, Ta alloy layer was prepared on surface by double glow plasma surface alloying technique. The tribology behavior of Ta alloy layer against Si3N4 at 25?, 350? and 500? were comparatively studied. The results showed that Ta alloy layer comprised a deposition layer and a diffusion layer. The deposition layer played a role in protection as a soft film. With the increase of temperature, the wear mechanism of ?-TiAl changed from abrasive wear to coexistence of abrasive wear and oxidation wear. Ta alloy layer?s wear mechanism changed from adhesive wear to coexistence of adhesive wear and oxidation wear. Surface Ta alloying process significantly reduced the wear volume, the specific wear rate and the friction coefficient of ?-TiAl and improved the wear resistance properties of ?-TiAl.
{"title":"Effects of plasma surface Ta alloying on the tribology behavior of γ-TiAl","authors":"D. Wei, Xiaoyong Zhou, Fengkun Li, M. Li, Shuqin Li, Pingze Zhang","doi":"10.2298/JMMB200617002W","DOIUrl":"https://doi.org/10.2298/JMMB200617002W","url":null,"abstract":"To improve the wear resistance of ?-TiAl alloy, Ta alloy layer was prepared on surface by double glow plasma surface alloying technique. The tribology behavior of Ta alloy layer against Si3N4 at 25?, 350? and 500? were comparatively studied. The results showed that Ta alloy layer comprised a deposition layer and a diffusion layer. The deposition layer played a role in protection as a soft film. With the increase of temperature, the wear mechanism of ?-TiAl changed from abrasive wear to coexistence of abrasive wear and oxidation wear. Ta alloy layer?s wear mechanism changed from adhesive wear to coexistence of adhesive wear and oxidation wear. Surface Ta alloying process significantly reduced the wear volume, the specific wear rate and the friction coefficient of ?-TiAl and improved the wear resistance properties of ?-TiAl.","PeriodicalId":51090,"journal":{"name":"Journal of Mining and Metallurgy Section B-Metallurgy","volume":"3 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88259423","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Slag viscosity is essential in high-temperature metallurgical processes. However, a slag viscosity model is difficult to exactly interpret as it has a strong nonlinear relation with its composition and temperature. In this paper, genetic programming (GP) was employed to derive a CaO-SiO2-Al2O3slag viscosity equation. The equation was automatically described as a simple algebraic equation with the basicity and content of Al2O3and temperature. The average relative error between the values obtained by the equation and the experimental data used for its derivation was as low as 17.1%. Computer simulations were performed to evaluate the accuracy of the derived viscosity equation and were then compared with many experimental viscosities and calculated values of other researchers. Slag compositions and temperatures for simulation calculations were the experimental data which were not used for deriving aviscosity equation. Our results showed that the viscosity equation was relatively exact. The viscosities of CaO-SiO2-Al2O3system slag could be simply and expediently predicted with in the wide range of compositions and temperatures by using the derived viscosity equation.
{"title":"Derivation of CaO-SiO2-Al2O3system slag viscosity equation by GP","authors":"Shen Ri, Junghwa Ra, K. Ryom, U.-D. Kim","doi":"10.2298/JMMB190919027R","DOIUrl":"https://doi.org/10.2298/JMMB190919027R","url":null,"abstract":"Slag viscosity is essential in high-temperature metallurgical processes. However, a slag viscosity model is difficult to exactly interpret as it has a strong nonlinear relation with its composition and temperature. In this paper, genetic programming (GP) was employed to derive a CaO-SiO2-Al2O3slag viscosity equation. The equation was automatically described as a simple algebraic equation with the basicity and content of Al2O3and temperature. The average relative error between the values obtained by the equation and the experimental data used for its derivation was as low as 17.1%. Computer simulations were performed to evaluate the accuracy of the derived viscosity equation and were then compared with many experimental viscosities and calculated values of other researchers. Slag compositions and temperatures for simulation calculations were the experimental data which were not used for deriving aviscosity equation. Our results showed that the viscosity equation was relatively exact. The viscosities of CaO-SiO2-Al2O3system slag could be simply and expediently predicted with in the wide range of compositions and temperatures by using the derived viscosity equation.","PeriodicalId":51090,"journal":{"name":"Journal of Mining and Metallurgy Section B-Metallurgy","volume":"164 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86742761","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Using a reduced pressure during the smelting and refining of alloys removes dissolved gasses, as well as impurities with a high vapor pressure. When smelting is carried out in vacuum induction furnaces, the intensification of the discussed processes is achieved by intensive mixing of the bath, as well as an enhanced mass exchange surface (liquid metal surface) due to the formation of a meniscus. This is due to the electromagnetic field applied to the liquid metal. This study reports the removal of arsenic from blister copper via refining in an induction vacuum furnace in the temperature range of 1423-1523 K, at operating pressures from 8 to 1333 Pa. The overall mass transfer coefficient kAs determined from the experimental data ranged from 9.99?10-7 to 1.65?10-5 ms-1. Arsenic elimination was largely controlled by mass transfer in the gas phase. The kinetic analysis indicated that the arsenic evaporation rate was controlled by the combination of both liquid and gas-phase mass transfer only at a pressure of 8 Pa.
{"title":"Removal of arsenic from liquid blister copper during remelting in an induction vacuum furnace","authors":"J. Łabaj, L. Blacha, A. Smalcerz, B. Chmiela","doi":"10.2298/jmmb210108033l","DOIUrl":"https://doi.org/10.2298/jmmb210108033l","url":null,"abstract":"Using a reduced pressure during the smelting and refining of alloys removes dissolved gasses, as well as impurities with a high vapor pressure. When smelting is carried out in vacuum induction furnaces, the intensification of the discussed processes is achieved by intensive mixing of the bath, as well as an enhanced mass exchange surface (liquid metal surface) due to the formation of a meniscus. This is due to the electromagnetic field applied to the liquid metal. This study reports the removal of arsenic from blister copper via refining in an induction vacuum furnace in the temperature range of 1423-1523 K, at operating pressures from 8 to 1333 Pa. The overall mass transfer coefficient kAs determined from the experimental data ranged from 9.99?10-7 to 1.65?10-5 ms-1. Arsenic elimination was largely controlled by mass transfer in the gas phase. The kinetic analysis indicated that the arsenic evaporation rate was controlled by the combination of both liquid and gas-phase mass transfer only at a pressure of 8 Pa.","PeriodicalId":51090,"journal":{"name":"Journal of Mining and Metallurgy Section B-Metallurgy","volume":"12 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87421426","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The present work represents a comparative study on the impurities removal from pig iron melt by addition of partially reduced highly fluxed direct reduced iron (DRI) to make steel in a 2 kg capacity electric arc furnace (EAF). Three types of fluxed DRI (30, 50, 80% Reduction (%R) with similar basicity-8) were used to maintain different level of oxidizing potential on the bath for studying the kinetic behaviour of impurities removal from melt. Results showed that the rate of removal of impurities (i.e. C, Si, Mn, P, S etc.) was increased initially up to 5 minutes of reaction time then decreased afterwards. Phosphorus (~64%), sulfur (~16%) and carbon (~94%) were removed simultaneously up to 25 minutes of reaction time using 30%R fluxed DRI. Similarly, phosphorus (~33%), sulfur (~50%) and carbon (~62%) were removed simultaneously using 50%R fluxed DRI while highly reduced (80%R) flux DRI removed sulfur (~58%), carbon (~56%) with a small fraction of phosphorus (~18%) from pig iron. It was observed in all the cases that silicon (>99%) and manganese (>80%) were removed. From the present study, it can be concluded that ~30%R DRI is favorable for effective phosphorus removal whereas ~80%R is favorable for sulfur removal. The significant removal of impurities could be achieved by charging ~50%R fluxed DRI in the pig iron melt.
{"title":"Effect of partially reduced highly fluxed DRI pellets on impurities removal during steelmaking using a laboratory scale EAF","authors":"R. K. Dishwar, O. P. Sinha","doi":"10.2298/jmmb210319050d","DOIUrl":"https://doi.org/10.2298/jmmb210319050d","url":null,"abstract":"The present work represents a comparative study on the impurities removal from pig iron melt by addition of partially reduced highly fluxed direct reduced iron (DRI) to make steel in a 2 kg capacity electric arc furnace (EAF). Three types of fluxed DRI (30, 50, 80% Reduction (%R) with similar basicity-8) were used to maintain different level of oxidizing potential on the bath for studying the kinetic behaviour of impurities removal from melt. Results showed that the rate of removal of impurities (i.e. C, Si, Mn, P, S etc.) was increased initially up to 5 minutes of reaction time then decreased afterwards. Phosphorus (~64%), sulfur (~16%) and carbon (~94%) were removed simultaneously up to 25 minutes of reaction time using 30%R fluxed DRI. Similarly, phosphorus (~33%), sulfur (~50%) and carbon (~62%) were removed simultaneously using 50%R fluxed DRI while highly reduced (80%R) flux DRI removed sulfur (~58%), carbon (~56%) with a small fraction of phosphorus (~18%) from pig iron. It was observed in all the cases that silicon (>99%) and manganese (>80%) were removed. From the present study, it can be concluded that ~30%R DRI is favorable for effective phosphorus removal whereas ~80%R is favorable for sulfur removal. The significant removal of impurities could be achieved by charging ~50%R fluxed DRI in the pig iron melt.","PeriodicalId":51090,"journal":{"name":"Journal of Mining and Metallurgy Section B-Metallurgy","volume":"42 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89108997","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The vanadium slag (V-slag) is generated from smelting vanadium titanomagnetite ore, which contains valuable elements, such as V, Ti, Cr, Fe and Mn. The traditional methods were mainly focused on the extractions of V and Cr by oxidation or reduction processes. In the present work, chlorination method was adopted to keep the valence state of each elements as original state. In order to speed up the diffusion of elements and reduce volatility of molten salt, microwave heating has been examined in the current paper. The results indicated that it only took 30 min to chlorinate V-slag at 800 ?C, and the chlorination ratios of V, Cr, Mn, Fe and Ti could reach to 82.67%, 75.82%, 92.96%, 91.66% and 63.14%, respectively. Compared with the results by conventional heating for 8 h, this extraction rate by microwave heating shows greater advantages. In addition, microwave heating can reduce effectively volatilization of AlCl3 by shortening the reaction time. The volatilization ratio of AlCl3 in this microwave heating was 3.92% instead of 8.97% in conventional heating (1h). The mechanism of efficient chlorination can be summarized as the enhancement of ions diffusion process and enhanced chemical reaction due to local high temperature.
{"title":"High efficiency extractions of V, Cr, Ti, Fe and Mn from vanadium slag by microwave heating","authors":"B. Tan, Wu Shun, Lijun Wang, K. Chou","doi":"10.2298/JMMB190827023T","DOIUrl":"https://doi.org/10.2298/JMMB190827023T","url":null,"abstract":"The vanadium slag (V-slag) is generated from smelting vanadium titanomagnetite ore, which contains valuable elements, such as V, Ti, Cr, Fe and Mn. The traditional methods were mainly focused on the extractions of V and Cr by oxidation or reduction processes. In the present work, chlorination method was adopted to keep the valence state of each elements as original state. In order to speed up the diffusion of elements and reduce volatility of molten salt, microwave heating has been examined in the current paper. The results indicated that it only took 30 min to chlorinate V-slag at 800 ?C, and the chlorination ratios of V, Cr, Mn, Fe and Ti could reach to 82.67%, 75.82%, 92.96%, 91.66% and 63.14%, respectively. Compared with the results by conventional heating for 8 h, this extraction rate by microwave heating shows greater advantages. In addition, microwave heating can reduce effectively volatilization of AlCl3 by shortening the reaction time. The volatilization ratio of AlCl3 in this microwave heating was 3.92% instead of 8.97% in conventional heating (1h). The mechanism of efficient chlorination can be summarized as the enhancement of ions diffusion process and enhanced chemical reaction due to local high temperature.","PeriodicalId":51090,"journal":{"name":"Journal of Mining and Metallurgy Section B-Metallurgy","volume":"1 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89820725","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：