J.-W. Wang, D. He, X. Wu, X. Guo, Z. Tan, Z. Zhou, W. Shao
In this research, the characteristics of Nickel-titanium (NiTi) powders produced by electrode induction melting inert gas atomization (EIGA) technique for additive manufacturing (AM) technology are investigated using various powder characterization technologies. The results show that the particle size distribution (PSD) of pre-alloyed NiTi powders prepared by EIGA has the range of 10 ?m to 180 ?m. The mean particle size distribution (D50) of the powder is 75 ?m. The oxygen increase of the powder is only 0.005% compared to the raw rod. According to the requirements of the characteristics of the metal powder material used for AM, the powders are sieved into three categories, P1 (15-63 ?m), P2 (63-150 ?m), and P3 (>150 ?m), respectively. The flow rates of P1, and P2 are 19.3 and 17.5 s?(50 g)-1, respectively. The surface, cross- sectional microstructure, phase structure and martensitic transformation temperature of the pre-alloyed NiTi powders with different particle sizes are investigated. The results show that powders of different particle sizes are primarily spherical or nearly spherical. The grain size of powders reduces with the decreasing of particle size. Both the bar stock and the powders of P1, P2, and P3 mainly exhibit the B2 phase. Comparing the powders P1, P2 and P3, the transformation temperature reduces with the decrease of particle size. A high density (99.55%) pre-alloyed NiTi specimen is successfully produced by selective laser melting (SLM) technology using P1 powders. The results indicate that the pre-alloyed NiTi alloy powder is appropriate for AM, which also has a good reference value for researchers producing AM powders.
{"title":"Characterization of pre-alloyed NiTi powders produced by electrode induction-melting inert gas atomization for additive manufacturing","authors":"J.-W. Wang, D. He, X. Wu, X. Guo, Z. Tan, Z. Zhou, W. Shao","doi":"10.2298/jmmb211019006w","DOIUrl":"https://doi.org/10.2298/jmmb211019006w","url":null,"abstract":"In this research, the characteristics of Nickel-titanium (NiTi) powders produced by electrode induction melting inert gas atomization (EIGA) technique for additive manufacturing (AM) technology are investigated using various powder characterization technologies. The results show that the particle size distribution (PSD) of pre-alloyed NiTi powders prepared by EIGA has the range of 10 ?m to 180 ?m. The mean particle size distribution (D50) of the powder is 75 ?m. The oxygen increase of the powder is only 0.005% compared to the raw rod. According to the requirements of the characteristics of the metal powder material used for AM, the powders are sieved into three categories, P1 (15-63 ?m), P2 (63-150 ?m), and P3 (>150 ?m), respectively. The flow rates of P1, and P2 are 19.3 and 17.5 s?(50 g)-1, respectively. The surface, cross- sectional microstructure, phase structure and martensitic transformation temperature of the pre-alloyed NiTi powders with different particle sizes are investigated. The results show that powders of different particle sizes are primarily spherical or nearly spherical. The grain size of powders reduces with the decreasing of particle size. Both the bar stock and the powders of P1, P2, and P3 mainly exhibit the B2 phase. Comparing the powders P1, P2 and P3, the transformation temperature reduces with the decrease of particle size. A high density (99.55%) pre-alloyed NiTi specimen is successfully produced by selective laser melting (SLM) technology using P1 powders. The results indicate that the pre-alloyed NiTi alloy powder is appropriate for AM, which also has a good reference value for researchers producing AM powders.","PeriodicalId":51090,"journal":{"name":"Journal of Mining and Metallurgy Section B-Metallurgy","volume":"5 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86080783","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}
Specular iron ores are medium grade iron ores suitable to use in agglomeration process. However, due to their hard texture, undesirable particle size and shape, poor assimilation performance and low reactivity at high temperature, its uses in agglomeration is very limited and restricted to almost 3-10% at most of the plant. In the present study effect of specular iron ore on sintering performance and sinter qualities are examined. It was observed that an increased proportion of specular iron ore in sinter blend has shown poor sintering performance in both laboratory scale studies and plant scale trials. In the present work, effect of blending of specular iron ore with goethite iron ore in sinter mix on sintering performance is examined and an optimum iron ore blend ratio for sustainable performance and quality is proposed. To increase the specular iron ore usage in sintering, goethitic iron ore up to 30% is introduced in sinter blend to overcome the deteriorating nature of specular iron ore. The goethite iron ore contains chemically bonded water which gets removed at higher temperatures (300-500?C) during sintering. The evaporated water gets cooled at lower bed and condenses which retards the air flow during sintering process and thus the combustion zone stays for longer time allowing better melt assimilation and sinter qualities. The poor melt assimilation of specularite is thus countered in presence of goethite iron ore. Having better reactive and hydrophilic nature of goethite iron ore, nullifying or reducing the ill effect of poor reactive and hydrophobic characteristics of specular iron ore during granulation and sintering process. Due to the which, the blended specular and goethite iron ore resulted in improved sintering rate and consequently improved sinter productivity. The present work proposed usage of up to 30% of specular iron ore when blended with goethite iron ore in sinter making.
{"title":"Improving the sinter productivity with increased specular iron ore in sinter blend","authors":"S. Kumar, A. Jaiswal, Roshan Sah","doi":"10.2298/jmmb210922009k","DOIUrl":"https://doi.org/10.2298/jmmb210922009k","url":null,"abstract":"Specular iron ores are medium grade iron ores suitable to use in agglomeration process. However, due to their hard texture, undesirable particle size and shape, poor assimilation performance and low reactivity at high temperature, its uses in agglomeration is very limited and restricted to almost 3-10% at most of the plant. In the present study effect of specular iron ore on sintering performance and sinter qualities are examined. It was observed that an increased proportion of specular iron ore in sinter blend has shown poor sintering performance in both laboratory scale studies and plant scale trials. In the present work, effect of blending of specular iron ore with goethite iron ore in sinter mix on sintering performance is examined and an optimum iron ore blend ratio for sustainable performance and quality is proposed. To increase the specular iron ore usage in sintering, goethitic iron ore up to 30% is introduced in sinter blend to overcome the deteriorating nature of specular iron ore. The goethite iron ore contains chemically bonded water which gets removed at higher temperatures (300-500?C) during sintering. The evaporated water gets cooled at lower bed and condenses which retards the air flow during sintering process and thus the combustion zone stays for longer time allowing better melt assimilation and sinter qualities. The poor melt assimilation of specularite is thus countered in presence of goethite iron ore. Having better reactive and hydrophilic nature of goethite iron ore, nullifying or reducing the ill effect of poor reactive and hydrophobic characteristics of specular iron ore during granulation and sintering process. Due to the which, the blended specular and goethite iron ore resulted in improved sintering rate and consequently improved sinter productivity. The present work proposed usage of up to 30% of specular iron ore when blended with goethite iron ore in sinter making.","PeriodicalId":51090,"journal":{"name":"Journal of Mining and Metallurgy Section B-Metallurgy","volume":"45 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89209189","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}
Fengjiao Deng, Guojing Xu, Wayne W. Fan, S. Li, Ruixin Ma
Because the traditional roasting-leaching-electrowinning zinc hydrometallurgy process has a small sulfuric acid sales radius and a high inventory pressure, the process of direct leaching zinc concentrate is gaining popularity. but the pressurized leaching process is a high-pressure condition, which requires strict equipment material and high safety requirements. Furthermore, the atmospheric leaching efficiency is low and generally introduces impurities and chloride ions, which increase the cost of subsequent decontamination. Therefore, a new environmentally friendly hydrometallurgy extraction method of zinc was proposed: an atmospheric pressure medium temperature sulfuric acid curing-leaching process. In an open-air condition, zinc sulfide concentrate was cured with sulfuric acid at different acid-to-ore ratios and heated to 220?C~260?C for a different time, then leaching the cured product. The effects of temperature, curing time, acid-to-ore ratio and sulfuric acid concentration on the leaching ratio of zinc (hZn) were studied. The results demonstrated that hZncould reach as high as 98.23% under the optimized conditions of temperature 240?C, curing time 2.5 hours, acid-to-ore ratio 1.4:1 and sulfuric acid concentration 60 wt.%. The leaching residue ratio is 6%, with silicate accounting for the majority of it. The kinetic results support the shrinking core model, which is controlled by an interface chemical reaction with an apparent activation energy of 43.158 kJ/mol.
{"title":"Atmospheric curing of zinc sulfide concentrate by sulfuric acid below 300°C","authors":"Fengjiao Deng, Guojing Xu, Wayne W. Fan, S. Li, Ruixin Ma","doi":"10.2298/jmmb220302016d","DOIUrl":"https://doi.org/10.2298/jmmb220302016d","url":null,"abstract":"Because the traditional roasting-leaching-electrowinning zinc hydrometallurgy process has a small sulfuric acid sales radius and a high inventory pressure, the process of direct leaching zinc concentrate is gaining popularity. but the pressurized leaching process is a high-pressure condition, which requires strict equipment material and high safety requirements. Furthermore, the atmospheric leaching efficiency is low and generally introduces impurities and chloride ions, which increase the cost of subsequent decontamination. Therefore, a new environmentally friendly hydrometallurgy extraction method of zinc was proposed: an atmospheric pressure medium temperature sulfuric acid curing-leaching process. In an open-air condition, zinc sulfide concentrate was cured with sulfuric acid at different acid-to-ore ratios and heated to 220?C~260?C for a different time, then leaching the cured product. The effects of temperature, curing time, acid-to-ore ratio and sulfuric acid concentration on the leaching ratio of zinc (hZn) were studied. The results demonstrated that hZncould reach as high as 98.23% under the optimized conditions of temperature 240?C, curing time 2.5 hours, acid-to-ore ratio 1.4:1 and sulfuric acid concentration 60 wt.%. The leaching residue ratio is 6%, with silicate accounting for the majority of it. The kinetic results support the shrinking core model, which is controlled by an interface chemical reaction with an apparent activation energy of 43.158 kJ/mol.","PeriodicalId":51090,"journal":{"name":"Journal of Mining and Metallurgy Section B-Metallurgy","volume":"15 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86591132","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}
In this paper, Ti6Al4V+3 wt.% TiB2 composite powder was used as a raw material to synthesize TiB whiskers in situ and prepare composites reinforced with TiB/Ti6Al4V whiskers by selective laser melting (SLM). The effects of process parameters on the properties of TiB/Ti6Al4V samples were systematically studied. The evolution of the microstructure, including the formation and regulation of whiskers, and the effects on mechanical properties were discussed. The results showed that during the SLM process, adjusting the energy density effectively inhibited cracking in the TiB/Ti6Al4V samples. The TiB2 particles acted as nucleation centers to significantly refine the grains during processing and reacted with elemental Ti to form a needle-like TiB network at the grain boundaries, which strengthened the whiskers. Additionally, TiB played a role in dispersion strengthening. Compared with Ti6Al4V, the microhardness of TiB/Ti6Al4V was 430.6?11.45 HV, an increase of 27.9%, and the wear volume of the sample was 0.85?10-3 mm3, a decrease of 62.64%.
{"title":"Microstructure evolution and mechanical properties of TiB/Ti6Al4V composites based on selective laser melting","authors":"X. Huang, Y. Zhu, W. Huang, Shuchen Qin, L. Wang","doi":"10.2298/jmmb220422025h","DOIUrl":"https://doi.org/10.2298/jmmb220422025h","url":null,"abstract":"In this paper, Ti6Al4V+3 wt.% TiB2 composite powder was used as a raw material to synthesize TiB whiskers in situ and prepare composites reinforced with TiB/Ti6Al4V whiskers by selective laser melting (SLM). The effects of process parameters on the properties of TiB/Ti6Al4V samples were systematically studied. The evolution of the microstructure, including the formation and regulation of whiskers, and the effects on mechanical properties were discussed. The results showed that during the SLM process, adjusting the energy density effectively inhibited cracking in the TiB/Ti6Al4V samples. The TiB2 particles acted as nucleation centers to significantly refine the grains during processing and reacted with elemental Ti to form a needle-like TiB network at the grain boundaries, which strengthened the whiskers. Additionally, TiB played a role in dispersion strengthening. Compared with Ti6Al4V, the microhardness of TiB/Ti6Al4V was 430.6?11.45 HV, an increase of 27.9%, and the wear volume of the sample was 0.85?10-3 mm3, a decrease of 62.64%.","PeriodicalId":51090,"journal":{"name":"Journal of Mining and Metallurgy Section B-Metallurgy","volume":"11 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72761871","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}
M. Rifai, M. Mujamilah, E. Bagherpour, H. Miyamoto
Effect of strain energy on corrosion behavior of ultrafine-grained (UFG) copper prepared by severe plastic deformation (SPD) was investigated in term of microstructural evolution. The SPD processed material showed an ultrafine-grained (UFG) structure after grain refinement for several time processes, which will affect mechanical and corrosion behavior. homogeneous, can be obtained efficiently through the pressing process or is commonly known as simple shear extrusion (SSE), which one of the SPD techniques. Pure copper was processed by SSE for two, four, eight and twelve passes. The structure of SSE treated sample was observed by laser microscope and transmission electron microscope as well as X-ray diffraction, The corrosion behavior by potentiodynamic polarization curve was observed modified Livingstone solution, 1 M NaCl and sulphuric solution. The structure of SSE processed showed that the first pass of the SSE processed sample showed large deformation by developing the elongated grain and sub-grain structure. By increasing the SSE pass number, the grain shape became equiaxed due to excessive strain. The X-ray broadening related to ultrafine-grained (UFG) structure processed SSE on the copper sample, leading to smaller crystallite size, higher microstrain, and higher dislocation density. The passive film was developed more homogeneous on the material with UFG structure appearance. However, the current density in 1 M NaCl decreased by an increment of pass number due to the dissolution of copper metal. The UFG structure has more boundaries than coarse grain structure, and these phenomena show why Cu dissolve ability influences the current density. The grain boundary behaves as the cathodic site.
从微观组织演化的角度研究了应变能对强塑性变形(SPD)制备超细晶铜腐蚀行为的影响。SPD处理后的材料经过多次的晶粒细化后呈现出超细晶(UFG)组织，这将影响材料的力学性能和腐蚀性能。均质，可以有效地通过挤压过程或通常被称为简单剪切挤压(SSE)，这是SPD技术之一。纯铜在SSE进行了2、4、8和12道工序。采用激光显微镜、透射电镜和x射线衍射观察了SSE处理后样品的结构，通过动电位极化曲线观察了改性Livingstone溶液、1 M NaCl和硫酸溶液的腐蚀行为。SSE处理后的组织表明，SSE处理后的试样在第一次加工时出现了较大的变形，形成了拉长晶和亚晶组织。通过增加SSE孔道数，晶粒形状因过度应变而趋于等轴。与超细晶(UFG)结构相关的x射线展宽在铜样品上处理SSE，导致更小的晶粒尺寸、更高的微应变和更高的位错密度。钝化膜在具有UFG结构外观的材料上形成更加均匀。但在1 M NaCl中，由于铜金属的溶解，电流密度随通道数的增加而降低。UFG结构比粗晶结构具有更多的边界，这些现象说明了Cu溶解能力影响电流密度的原因。晶界表现为阴极区。
{"title":"Effect of strain energy on corrosion behavior of ultrafine grained copper prepared by severe plastic deformation","authors":"M. Rifai, M. Mujamilah, E. Bagherpour, H. Miyamoto","doi":"10.2298/jmmb220101015r","DOIUrl":"https://doi.org/10.2298/jmmb220101015r","url":null,"abstract":"Effect of strain energy on corrosion behavior of ultrafine-grained (UFG) copper prepared by severe plastic deformation (SPD) was investigated in term of microstructural evolution. The SPD processed material showed an ultrafine-grained (UFG) structure after grain refinement for several time processes, which will affect mechanical and corrosion behavior. homogeneous, can be obtained efficiently through the pressing process or is commonly known as simple shear extrusion (SSE), which one of the SPD techniques. Pure copper was processed by SSE for two, four, eight and twelve passes. The structure of SSE treated sample was observed by laser microscope and transmission electron microscope as well as X-ray diffraction, The corrosion behavior by potentiodynamic polarization curve was observed modified Livingstone solution, 1 M NaCl and sulphuric solution. The structure of SSE processed showed that the first pass of the SSE processed sample showed large deformation by developing the elongated grain and sub-grain structure. By increasing the SSE pass number, the grain shape became equiaxed due to excessive strain. The X-ray broadening related to ultrafine-grained (UFG) structure processed SSE on the copper sample, leading to smaller crystallite size, higher microstrain, and higher dislocation density. The passive film was developed more homogeneous on the material with UFG structure appearance. However, the current density in 1 M NaCl decreased by an increment of pass number due to the dissolution of copper metal. The UFG structure has more boundaries than coarse grain structure, and these phenomena show why Cu dissolve ability influences the current density. The grain boundary behaves as the cathodic site.","PeriodicalId":51090,"journal":{"name":"Journal of Mining and Metallurgy Section B-Metallurgy","volume":"96 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78599331","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}
As a refractory industrial solid waste, high-alumina fly ash is discharged into nature in large quantities, causing serious environmental harm. The extraction of valuable components, such as aluminum, from high-alumina fly ash has become a research hotspot at home and abroad. The shortcomings of traditional alumina extraction from high-alumina fly ash include long technological processes, large amounts of waste acid and alkali, and serious equipment corrosion. A novel method for alumina preparation by electrotransformation AlCl3 solution(EAS) under NH4Cl catalysis with injected CO2 has been proposed by Northeastern University. The process has advantages, such as short flow and no waste acid discharge. In this study, the influence of initial NH4Cl concentration in the cathodic chamber on solution pH, phase and morphology of electrotransformation products, phase, D(50) and D(90) of roasting products, and Al recovery rate were examined. Simultaneously, EAS was examined and compared with and without injected CO2 as well as EAS under NH4Cl catalysis with and without injected CO2. The results showed that, when the solution in the cathodic chamber was NH4Cl with CO2 injection, with electrotransformation time extension, pH increased slowly and the morphology of electrotransformation products were all rough and fluffy block structures. Increasing initial NH4Cl concentration effectively improved the product crystallization states, roasting products D(50) and D(90), and Al recovery rate.
{"title":"A novel method for alumina preparation by electrotransformation AlCl3 solution under NH4Cl-catalyzed and CO2-injected conditions","authors":"X. Han, Y.M. Liu, L.X. Yang, Y. Lu, R.-T. Wang, T.-A. Zhang","doi":"10.2298/jmmb220305021h","DOIUrl":"https://doi.org/10.2298/jmmb220305021h","url":null,"abstract":"As a refractory industrial solid waste, high-alumina fly ash is discharged into nature in large quantities, causing serious environmental harm. The extraction of valuable components, such as aluminum, from high-alumina fly ash has become a research hotspot at home and abroad. The shortcomings of traditional alumina extraction from high-alumina fly ash include long technological processes, large amounts of waste acid and alkali, and serious equipment corrosion. A novel method for alumina preparation by electrotransformation AlCl3 solution(EAS) under NH4Cl catalysis with injected CO2 has been proposed by Northeastern University. The process has advantages, such as short flow and no waste acid discharge. In this study, the influence of initial NH4Cl concentration in the cathodic chamber on solution pH, phase and morphology of electrotransformation products, phase, D(50) and D(90) of roasting products, and Al recovery rate were examined. Simultaneously, EAS was examined and compared with and without injected CO2 as well as EAS under NH4Cl catalysis with and without injected CO2. The results showed that, when the solution in the cathodic chamber was NH4Cl with CO2 injection, with electrotransformation time extension, pH increased slowly and the morphology of electrotransformation products were all rough and fluffy block structures. Increasing initial NH4Cl concentration effectively improved the product crystallization states, roasting products D(50) and D(90), and Al recovery rate.","PeriodicalId":51090,"journal":{"name":"Journal of Mining and Metallurgy Section B-Metallurgy","volume":"23 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79420020","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}
E. Santo, S. G. Soares, O. de, E. Junca, F. Grillo
The steel production enhancement in recent decades has increased the solid waste generation in the steel plants. Due to the increase in the environmental policies stringency, efforts have been made to give them a more appropriate destination. In this context, the internal reuse of these materials is a solution often applied by the industry to reduce production costs and to decrease slag generation. Therefore, the aim of this research is to replace calcitic lime by limestone waste and KR slag in hot metal desulfurization, which are wastes from steel production. The KR slag is the waste generated by the desulfurization process in Kambara Reactor. Experimental desulfurization tests were carried out in a resistance furnace at a temperature of 1350?C, in an inert atmosphere with constant stirring of 500 rpm. Along with the tests, simulations were carried out with FactSage 7.0 software in order to obtain the phases present in each mixture at the working temperature and compare them with the practical results. It was found that the tricalcium silicate phase (3CaO?SiO2) was present in mixtures with lower desulfurization efficiency, which shows its kinetic limitation. The use of limestone waste proved to be more efficient than the use of KR slag.
{"title":"Replacement of lime with industrial wastes in hot metal desulfurization mixtures","authors":"E. Santo, S. G. Soares, O. de, E. Junca, F. Grillo","doi":"10.2298/jmmb210407005s","DOIUrl":"https://doi.org/10.2298/jmmb210407005s","url":null,"abstract":"The steel production enhancement in recent decades has increased the solid waste generation in the steel plants. Due to the increase in the environmental policies stringency, efforts have been made to give them a more appropriate destination. In this context, the internal reuse of these materials is a solution often applied by the industry to reduce production costs and to decrease slag generation. Therefore, the aim of this research is to replace calcitic lime by limestone waste and KR slag in hot metal desulfurization, which are wastes from steel production. The KR slag is the waste generated by the desulfurization process in Kambara Reactor. Experimental desulfurization tests were carried out in a resistance furnace at a temperature of 1350?C, in an inert atmosphere with constant stirring of 500 rpm. Along with the tests, simulations were carried out with FactSage 7.0 software in order to obtain the phases present in each mixture at the working temperature and compare them with the practical results. It was found that the tricalcium silicate phase (3CaO?SiO2) was present in mixtures with lower desulfurization efficiency, which shows its kinetic limitation. The use of limestone waste proved to be more efficient than the use of KR slag.","PeriodicalId":51090,"journal":{"name":"Journal of Mining and Metallurgy Section B-Metallurgy","volume":"12 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83633945","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 paper investigated the thermodynamics and kinetics of carbothermal reduction of fayalite by non-isothermal method combining with thermogravimetric analyzer and applying the Flynn-Wall-Ozawa (FWO) and M?lek models. According to the thermodynamic analysis, the starting temperature of direct reduction reaction of fayalite is 806.79?C in the standard state. The indirect reduction reaction can not take place in the standard state. While the volume percentage of CO is higher than 86 vol.% in nonstandard state, the indirect reduction can take place in the range of experimental temperature. Meanwhile, Boudouard reaction can promote the indirect reduction process. The kinetic analysis results show that at the temperature below 1100?C, the main reduction reaction is the direct reduction between fayalite and graphite. With the temperature increasing, the fayalite reacts with CO generated from the gasification of graphite. When the reduction rate increases from 0% to 50%, the activation energy of the reaction increases to 524.41 kJ/mol. Then, the activation energy decreases with the increase of reduction rate. The carbothermal reduction of fayalite is multistep reaction. The controlling step in the initial stage is the gasification of graphite. As the reaction proceeding, the generated CO provides a good kinetics condition for the carbothermal reduction of fayalite, and the controlling step of the reaction is the nucleation and growth of the metallic iron.
{"title":"Carbothermal reduction of fayalite: Thermodynamic and non-isothermal kinetic analysis","authors":"Z. Li, G. Ma, J. Zou, Dingli Zheng, X. Zhang","doi":"10.2298/jmmb210323022l","DOIUrl":"https://doi.org/10.2298/jmmb210323022l","url":null,"abstract":"The present paper investigated the thermodynamics and kinetics of carbothermal reduction of fayalite by non-isothermal method combining with thermogravimetric analyzer and applying the Flynn-Wall-Ozawa (FWO) and M?lek models. According to the thermodynamic analysis, the starting temperature of direct reduction reaction of fayalite is 806.79?C in the standard state. The indirect reduction reaction can not take place in the standard state. While the volume percentage of CO is higher than 86 vol.% in nonstandard state, the indirect reduction can take place in the range of experimental temperature. Meanwhile, Boudouard reaction can promote the indirect reduction process. The kinetic analysis results show that at the temperature below 1100?C, the main reduction reaction is the direct reduction between fayalite and graphite. With the temperature increasing, the fayalite reacts with CO generated from the gasification of graphite. When the reduction rate increases from 0% to 50%, the activation energy of the reaction increases to 524.41 kJ/mol. Then, the activation energy decreases with the increase of reduction rate. The carbothermal reduction of fayalite is multistep reaction. The controlling step in the initial stage is the gasification of graphite. As the reaction proceeding, the generated CO provides a good kinetics condition for the carbothermal reduction of fayalite, and the controlling step of the reaction is the nucleation and growth of the metallic iron.","PeriodicalId":51090,"journal":{"name":"Journal of Mining and Metallurgy Section B-Metallurgy","volume":"54 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79459358","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}
This paper investigated the wear performances of Y2O3 doped MA6000 (Ni-Cr-Al) alloy produced by mechanical alloying (MA). Produced, all powders were pre-formed by cold pressing and sintered in a vacuum environment. Sintered MA6000-X% Y2O3 superalloys were characterized by scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), X-ray diffraction (XRD) analysis, density, and hardness measurements. Wear tests of Y2O3 added MA6000 alloys were carried out in a block-on-ring type wear device. In the wear tests, the sliding speed of 1 ms-1 at room temperature (RT) was performed under five different sliding distances (200-1000m) and three different loads (5 N, 10 N, and 15 N). As a result of the studies, it was determined that the MA?ed MA6000 superalloy powders were homogeneous and flake shape. With the increase amount of Y2O3, hardness of these superalloys increased from 267 to 431 Hv, but the density slightly decreased. Different intermetallic/carbur phases such as Ni3Al, MoC are observed in all compositions. Wear tests show that weight loss and wear rate decreased, and friction coefficient (?) increased with the increasing amount of Y2O3 additive. Besides, it was determined that as the applied load increased in the wear test, the weight loss increased, but the wear rate and friction coefficient (?) decreased.
{"title":"The effect on wear behavior of the amount of Y2O3 doped to the MA6000 alloy produced by mechanical alloying method","authors":"S. Çelik, D. Özyürek, T. Tunçay","doi":"10.2298/jmmb220113010c","DOIUrl":"https://doi.org/10.2298/jmmb220113010c","url":null,"abstract":"This paper investigated the wear performances of Y2O3 doped MA6000 (Ni-Cr-Al) alloy produced by mechanical alloying (MA). Produced, all powders were pre-formed by cold pressing and sintered in a vacuum environment. Sintered MA6000-X% Y2O3 superalloys were characterized by scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), X-ray diffraction (XRD) analysis, density, and hardness measurements. Wear tests of Y2O3 added MA6000 alloys were carried out in a block-on-ring type wear device. In the wear tests, the sliding speed of 1 ms-1 at room temperature (RT) was performed under five different sliding distances (200-1000m) and three different loads (5 N, 10 N, and 15 N). As a result of the studies, it was determined that the MA?ed MA6000 superalloy powders were homogeneous and flake shape. With the increase amount of Y2O3, hardness of these superalloys increased from 267 to 431 Hv, but the density slightly decreased. Different intermetallic/carbur phases such as Ni3Al, MoC are observed in all compositions. Wear tests show that weight loss and wear rate decreased, and friction coefficient (?) increased with the increasing amount of Y2O3 additive. Besides, it was determined that as the applied load increased in the wear test, the weight loss increased, but the wear rate and friction coefficient (?) decreased.","PeriodicalId":51090,"journal":{"name":"Journal of Mining and Metallurgy Section B-Metallurgy","volume":"67 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90762591","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 melting point and phase of slag was calculated with Factsage thermodynamics software, and base on this, taking desulfurization slag as the main raw material, which is leached by ammonium chloride as pretreatment. The composition of target slag system was adjusted with high aluminum powder coal ash and glass cullet, and then the reducing slag and metallic iron were separated by high temperature carbon thermal reaction. The prepared glass-ceramics with main crystal phases of diopside and nepheline were obtained by heat treatment, which shows that the new process is feasible. The crystallization activation energy was calculated by using Kissinger, Ozawa and Augis-Bennett method base on the differential heat curve. The results show that the crystallization activation energy is relatively high, and the crystal growth index n are all less than 3, which means that the crystallization capacity of the glass-ceramics is low. At the heating rate of 5 K/min, the n value of sample No. 3 is the largest, which is 2.7, and the mode of volumetric crystallization changes from two-dimensional to one-dimensional with the increase of heating rate, therefore, nucleating agent is needed in the preparation of glass-ceramics.
{"title":"Study on a New Process and its Kinetics of Iron Recovery and Glass-ceramics Preparation from Desulfurization Slag","authors":"Zhibo Tong, Jing-jing Sun, Shichang Liu, Wei Zhang, MeiLing Kuang","doi":"10.21203/rs.3.rs-657986/v1","DOIUrl":"https://doi.org/10.21203/rs.3.rs-657986/v1","url":null,"abstract":"\u0000 The melting point and phase of slag was calculated with Factsage thermodynamics software, and base on this, taking desulfurization slag as the main raw material, which is leached by ammonium chloride as pretreatment. The composition of target slag system was adjusted with high aluminum powder coal ash and glass cullet, and then the reducing slag and metallic iron were separated by high temperature carbon thermal reaction. The prepared glass-ceramics with main crystal phases of diopside and nepheline were obtained by heat treatment, which shows that the new process is feasible. The crystallization activation energy was calculated by using Kissinger, Ozawa and Augis-Bennett method base on the differential heat curve. The results show that the crystallization activation energy is relatively high, and the crystal growth index n are all less than 3, which means that the crystallization capacity of the glass-ceramics is low. At the heating rate of 5 K/min, the n value of sample No. 3 is the largest, which is 2.7, and the mode of volumetric crystallization changes from two-dimensional to one-dimensional with the increase of heating rate, therefore, nucleating agent is needed in the preparation of glass-ceramics.","PeriodicalId":51090,"journal":{"name":"Journal of Mining and Metallurgy Section B-Metallurgy","volume":"61 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2021-07-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86897638","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}
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