In this paper, Ag containing in lead-silver slag was recovered during the melt-vaporization process, the existent state of Ag in soot was analyzed, the influence of reaction temperature, the carbon ratio, and reaction time on the removal rate of silver was explored, and process conditions were optimized by using the response surface methodology. Silver chloride, silver metal, silver sulfide, silver oxide, and silver sulfate are the main silver phases in the lead-silver slag, among which silver chloride and silver sulfide are major phases. The silver oxide (Ag2O) and silver chloride (AgCl) in the lead-silver slag volatilize into soot, the silver sulfide (Ag2S) is oxidized by oxygen to form silver sulfate (Ag2SO4), and elemental silver volatilizes with Pb and Zn to form alloys. The silver in the final exists as Ag, AgCl, Ag2O and Ag2SO4 in the soot. The removal rate of silver increases gradually with increasing reaction temperature and tends to remain stable at 1300?C. With a gradual increase in the carbon ratio, the removal rate of silver first increases and then decreases, and the highest value is 80.12 wt% when the carbon ratio is 16.30 wt%. With increasing holding time, the removal rate of silver increases gradually and then stabilizes about 79.97 wt% even at the holding time of 150 min. The optimum process conditions for silver removal are a reaction temperature of 1340?C, a carbon ratio of 16.10 wt%, and a holding time of 165 min, and the average removal rate of silver under these conditions is 80.42 wt%. The research in this paper lays a theoretical foundation for the removal and utilization of silver from lead and silver residue.
{"title":"Existent state and removal rate of silver in lead-silver slag during the melt-vaporization process","authors":"Y.-Y. Shen, X.-S. Zhao, F.-J. Zhang, W.-X. Ma, X.-F. Wang, X.-Y. Du","doi":"10.2298/jmmb230519030s","DOIUrl":"https://doi.org/10.2298/jmmb230519030s","url":null,"abstract":"In this paper, Ag containing in lead-silver slag was recovered during the melt-vaporization process, the existent state of Ag in soot was analyzed, the influence of reaction temperature, the carbon ratio, and reaction time on the removal rate of silver was explored, and process conditions were optimized by using the response surface methodology. Silver chloride, silver metal, silver sulfide, silver oxide, and silver sulfate are the main silver phases in the lead-silver slag, among which silver chloride and silver sulfide are major phases. The silver oxide (Ag2O) and silver chloride (AgCl) in the lead-silver slag volatilize into soot, the silver sulfide (Ag2S) is oxidized by oxygen to form silver sulfate (Ag2SO4), and elemental silver volatilizes with Pb and Zn to form alloys. The silver in the final exists as Ag, AgCl, Ag2O and Ag2SO4 in the soot. The removal rate of silver increases gradually with increasing reaction temperature and tends to remain stable at 1300?C. With a gradual increase in the carbon ratio, the removal rate of silver first increases and then decreases, and the highest value is 80.12 wt% when the carbon ratio is 16.30 wt%. With increasing holding time, the removal rate of silver increases gradually and then stabilizes about 79.97 wt% even at the holding time of 150 min. The optimum process conditions for silver removal are a reaction temperature of 1340?C, a carbon ratio of 16.10 wt%, and a holding time of 165 min, and the average removal rate of silver under these conditions is 80.42 wt%. The research in this paper lays a theoretical foundation for the removal and utilization of silver from lead and silver residue.","PeriodicalId":16479,"journal":{"name":"Journal of Mining and Metallurgy, Section B","volume":"2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135448863","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
C.-H. Wu, Y. Li, Y-D. Liu, X. Xie, G.-R. Wu, M. Zhang
During the continuous casting process, the remaining oxygen in the tundish can be significantly decreased by argon blowing from the tundish cover(ABTC). As a result, the effect of protective casting can be obviously improved, which helps decrease the reoxidation of molten steel in tundish. In the present work, numerical models for ABTC of a six-strand continuous casting machine were established and verified by the measured oxygen mass fraction in tundish during ABTC. The results indicate that the best conditions of ABTC are installing the argon pipes on either side of the tundish cover holes, sealing the baking holes, and keeping stopper rod holes open. The argon flow rate should be ?120m3/h during the period of empty tundish and ?60m3/h during the period of normal casting. Industrial trials of ABTC based on the calculation results were carried out. The results indicated that the increased nitrogen in steel(?w[N]) from the end of RH to tundish decreased by 21.5% from 8.78?10-6 to 6.89?10-6, and the amount of inclusions except for MnS in bloom (scanned size: 8mm?8mm) decreased by 21.3% from 13.43 to 10.57, and the average size of inclusions decreased by 19.0% from 9.27?m to 7.51?m.
{"title":"Numerical simulation and application of argon blowing from tundish cover for bloom continuous casting","authors":"C.-H. Wu, Y. Li, Y-D. Liu, X. Xie, G.-R. Wu, M. Zhang","doi":"10.2298/jmmb221027027w","DOIUrl":"https://doi.org/10.2298/jmmb221027027w","url":null,"abstract":"During the continuous casting process, the remaining oxygen in the tundish can be significantly decreased by argon blowing from the tundish cover(ABTC). As a result, the effect of protective casting can be obviously improved, which helps decrease the reoxidation of molten steel in tundish. In the present work, numerical models for ABTC of a six-strand continuous casting machine were established and verified by the measured oxygen mass fraction in tundish during ABTC. The results indicate that the best conditions of ABTC are installing the argon pipes on either side of the tundish cover holes, sealing the baking holes, and keeping stopper rod holes open. The argon flow rate should be ?120m3/h during the period of empty tundish and ?60m3/h during the period of normal casting. Industrial trials of ABTC based on the calculation results were carried out. The results indicated that the increased nitrogen in steel(?w[N]) from the end of RH to tundish decreased by 21.5% from 8.78?10-6 to 6.89?10-6, and the amount of inclusions except for MnS in bloom (scanned size: 8mm?8mm) decreased by 21.3% from 13.43 to 10.57, and the average size of inclusions decreased by 19.0% from 9.27?m to 7.51?m.","PeriodicalId":16479,"journal":{"name":"Journal of Mining and Metallurgy, Section B","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135448564","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The paper presents results of modeling and testing of a heavy weight part made of Cr-Mo, which was V-modified ultra-high strength steel grade AISI 4140, processed through a novel open-die forging schedule and two alternative routes of two-stage heat treatment cycles designed to meet requirements of high-duty components for energy sector. Taking advantage of unconventional forging conditions based on assumption of large feed and reduction ratios and the modification of chemical composition better control of austenite grain was achieved to minimize abnormal grain growth and/or strain uniformity problems. With aid of Finite Element Modeling of multi-stage sequence of upsetting and cogging strain distribution was optimized so as to minimize strain fluctuations on the length to range 2.2?2.7,and correlated with microstructure produced at every major stage on the large cross-sections of the shaft. Designed with aid of finite element method processing cycles was verified in full-scale physical modeling with use of 16 ton forging ingot, including two alternative quenching strategies: oil vs. water spray and air. Examination of material in as-forged, normalized and heat-treated condition was carried out to observe response of hot-worked material and the effect of cooling conditions on microstructure during final heat treatment. As observed, employing large feed ratios on cogging and varied cooling allowed suppress detrimental effect of inevitable abnormal grain growth which resulted in 1-2 ASTM grain in as-forged conditions to reach 6 ASTM in normalized and 8/9 ASTM after quenching in oil and water spray, respectively, which allows producing after tempering, correspondingly, 44?48 and 85?122 J/cm2 V-notch impact strength in the critical area of the forged shaft.
{"title":"Effect of forging sequence and heat treatment on microstructure of high-duty power-plant shaft made of Cr-Mo ultra-high strength steel","authors":"P. Skubisz, Ł. Lisiecki","doi":"10.2298/jmmb221005026s","DOIUrl":"https://doi.org/10.2298/jmmb221005026s","url":null,"abstract":"The paper presents results of modeling and testing of a heavy weight part made of Cr-Mo, which was V-modified ultra-high strength steel grade AISI 4140, processed through a novel open-die forging schedule and two alternative routes of two-stage heat treatment cycles designed to meet requirements of high-duty components for energy sector. Taking advantage of unconventional forging conditions based on assumption of large feed and reduction ratios and the modification of chemical composition better control of austenite grain was achieved to minimize abnormal grain growth and/or strain uniformity problems. With aid of Finite Element Modeling of multi-stage sequence of upsetting and cogging strain distribution was optimized so as to minimize strain fluctuations on the length to range 2.2?2.7,and correlated with microstructure produced at every major stage on the large cross-sections of the shaft. Designed with aid of finite element method processing cycles was verified in full-scale physical modeling with use of 16 ton forging ingot, including two alternative quenching strategies: oil vs. water spray and air. Examination of material in as-forged, normalized and heat-treated condition was carried out to observe response of hot-worked material and the effect of cooling conditions on microstructure during final heat treatment. As observed, employing large feed ratios on cogging and varied cooling allowed suppress detrimental effect of inevitable abnormal grain growth which resulted in 1-2 ASTM grain in as-forged conditions to reach 6 ASTM in normalized and 8/9 ASTM after quenching in oil and water spray, respectively, which allows producing after tempering, correspondingly, 44?48 and 85?122 J/cm2 V-notch impact strength in the critical area of the forged shaft.","PeriodicalId":16479,"journal":{"name":"Journal of Mining and Metallurgy, Section B","volume":"16 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135448566","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
T. Radetic, M. Popovic, M. Novakovic, V. Rajic, E. Romhanji
The Fe-bearing intermetallic phases present in the as-cast state of an AA6026 alloy and their evolution during homogenization treatments at 480-550?C were studied by optical microscopy, SEM, and TEM techniques combined with EDS analysis. Besides the ?- Al(Fe,Mn)Si phase of dendritic morphology, two types of plate-like Fe-bearing microconstituents were revealed in the microstructure of the as-cast alloy. The EDS microanalysis and electron diffraction showed that one set of platelets represents just thin sections of ?-Al(Fe,Mn)Si microconstituent. The other set of plate-like microconstituents was identified as a tetragonal, silicon-rich ?-Al4(Fe,Mn)Si2 phase. The formation of the ?- Al4(Fe,Mn)Si2 phase has been attributed to the chemical composition of the alloy. During homogenization, metastable ?-Al4(Fe,Mn)Si2 transformed into the ?-Al(Fe,Mn)Si phase and fragmented. The dendritic ?-Al(Fe,Mn)Si microconstituents underwent fragmentation as well. However, whereas ?-Al(Fe,Mn)Si microconstituents preserve b.c.c. crystal lattice throughout the process, the product of the transformation of the ?-Al4(Fe,Mn)Si2 phase exhibited primitive cubic lattice.
{"title":"Identification of Fe-bearing phases in the as-cast microstructure of AA6026 alloy and their evolution during homogenization treatment","authors":"T. Radetic, M. Popovic, M. Novakovic, V. Rajic, E. Romhanji","doi":"10.2298/jmmb230611028r","DOIUrl":"https://doi.org/10.2298/jmmb230611028r","url":null,"abstract":"The Fe-bearing intermetallic phases present in the as-cast state of an AA6026 alloy and their evolution during homogenization treatments at 480-550?C were studied by optical microscopy, SEM, and TEM techniques combined with EDS analysis. Besides the ?- Al(Fe,Mn)Si phase of dendritic morphology, two types of plate-like Fe-bearing microconstituents were revealed in the microstructure of the as-cast alloy. The EDS microanalysis and electron diffraction showed that one set of platelets represents just thin sections of ?-Al(Fe,Mn)Si microconstituent. The other set of plate-like microconstituents was identified as a tetragonal, silicon-rich ?-Al4(Fe,Mn)Si2 phase. The formation of the ?- Al4(Fe,Mn)Si2 phase has been attributed to the chemical composition of the alloy. During homogenization, metastable ?-Al4(Fe,Mn)Si2 transformed into the ?-Al(Fe,Mn)Si phase and fragmented. The dendritic ?-Al(Fe,Mn)Si microconstituents underwent fragmentation as well. However, whereas ?-Al(Fe,Mn)Si microconstituents preserve b.c.c. crystal lattice throughout the process, the product of the transformation of the ?-Al4(Fe,Mn)Si2 phase exhibited primitive cubic lattice.","PeriodicalId":16479,"journal":{"name":"Journal of Mining and Metallurgy, Section B","volume":"25 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135448563","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
There has been a significant increase in research and development efforts to meet the growing demand for environmentally friendly magnesium (Mg) alloys. Studies are currently exploring various alloying element combinations to meet demanding specifications. In this study, it was aimed to examine the usability of aluminum (Al), calcium (Ca), and zinc (Zn) elements together with barium (Ba), and to investigate the mechanical and thermodynamic properties of the obtained multicomponent alloy system. SEM and hardness tests were used to examine the microstructural and mechanical features of Mg alloys. In the SEM analysis, the alloy was determined to consist of an ?-Mg matrix, a blocky compact structure containing Ba (Mg17Ba2), a regional eutectic structure (Ca2Mg6Zn3), and independently growing lamellae (Al2Ca). The general hardness analysis results of the alloy, measured with Brinell and Vickers tests, were determined to be ~77 and ~82, respectively. The indentation test also revealed that stress transfer to the Al2Ca laves phase is possible, depending on the orientation of the slip plane between the matrix and the Al2Ca phase. It was also observed that cracks developed in the indentation test on the Mg17Ba2 intermetallic phase were only formed in the high-stress regions of the structure, and their propagation was limited. According to thermodynamic analysis, the ?Hmix value is -2.73 kJ/mol, the ?Smix value is 5.95 J/molK, the ? value is 34%, the ?? value is 0.14, and the ? value is 2.03. The obtained thermodynamic data were found to be compatible with the microstructural development of the alloy.
{"title":"Microstructural, mechanical and thermodynamic properties ınvestigation of the novel rare earth-free multicomponent Mg-15Al-8Ca-3Zn-2Ba alloy","authors":"Y. Türe","doi":"10.2298/jmmb230308029t","DOIUrl":"https://doi.org/10.2298/jmmb230308029t","url":null,"abstract":"There has been a significant increase in research and development efforts to meet the growing demand for environmentally friendly magnesium (Mg) alloys. Studies are currently exploring various alloying element combinations to meet demanding specifications. In this study, it was aimed to examine the usability of aluminum (Al), calcium (Ca), and zinc (Zn) elements together with barium (Ba), and to investigate the mechanical and thermodynamic properties of the obtained multicomponent alloy system. SEM and hardness tests were used to examine the microstructural and mechanical features of Mg alloys. In the SEM analysis, the alloy was determined to consist of an ?-Mg matrix, a blocky compact structure containing Ba (Mg17Ba2), a regional eutectic structure (Ca2Mg6Zn3), and independently growing lamellae (Al2Ca). The general hardness analysis results of the alloy, measured with Brinell and Vickers tests, were determined to be ~77 and ~82, respectively. The indentation test also revealed that stress transfer to the Al2Ca laves phase is possible, depending on the orientation of the slip plane between the matrix and the Al2Ca phase. It was also observed that cracks developed in the indentation test on the Mg17Ba2 intermetallic phase were only formed in the high-stress regions of the structure, and their propagation was limited. According to thermodynamic analysis, the ?Hmix value is -2.73 kJ/mol, the ?Smix value is 5.95 J/molK, the ? value is 34%, the ?? value is 0.14, and the ? value is 2.03. The obtained thermodynamic data were found to be compatible with the microstructural development of the alloy.","PeriodicalId":16479,"journal":{"name":"Journal of Mining and Metallurgy, Section B","volume":"28 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135448568","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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