International Journal of Minerals, Metallurgy and Materials

姓名
邮箱
手机号码
标题
留言内容
验证码

Magnetic separation studies on ferruginous chromite fine to enhance Cr:Fe ratio

Sunil Kumar Tripathy, P. K. Banerjee, Nikkam Suresh

2015, 22(3): 217-224. doi: 10.1007/s12613-015-1064-4

中文摘要(328) PDF(16) SpringerLink

摘要:
The Cr:Fe ratio (chromium-to-iron mass ratio) of chromite affects the production of chrome-based ferroalloys. Although the literature contains numerous reports related to the magnetic separation of different minerals, limited work concerning the application of magnetic separation to fine chromite from the Sukinda region of India to enhance its Cr:Fe ratio has been reported. In the present investigation, magnetic separation and mineralogical characterization studies of chromite fines were conducted to enhance the Cr:Fe ratio. Characterization studies included particle size and chemical analyses, X-ray diffraction analysis, automated mineral analysis, sink-and-float studies, and magnetic susceptibility measurements, whereas magnetic separation was investigated using a rare earth drum magnetic separator, a rare earth roll magnetic separator, an induced roll magnetic separator, and a wet high-intensity magnetic separator. The fine chromite was observed to be upgraded to a Cr:Fe ratio of 2.2 with a yield of 55.7% through the use of an induced roll magnetic separator and a feed material with a Cr:Fe ratio of 1.6.

Structural, microstructural, and thermal characterizations of a chalcopyrite concentrate from the Singhbhum shear zone, India

Ritayan Chatterjee, Shamik Chaudhuri, Saikat Kumar Kuila, Dinabandhu Ghosh

2015, 22(3): 225-232. doi: 10.1007/s12613-015-1065-3

中文摘要(277) PDF(9) SpringerLink

摘要:
The structural and morphological characterizations of a chalcopyrite concentrate, collected from the Indian Copper Complex, Ghatshila, India, were carried out by X-ray diffraction, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. The concentrate powder was composed mainly of free chalcopyrite and low quartz in about 3:1 weight ratio. The particle size was about 100 μm. Spectroscopic studies (FTIR, Raman, UV-visible) of the concentrate supported the XRD findings, and also revealed a marginal oxidation of the sulfide phase. The energy band gap of the sulfide was found to be 3.4 eV. Differential thermal analysis and thermogravimetry of the concentrate showed a decomposition of chalcopyrite at 658 K with an activation energy of 208 kJ·mol^-1, and two successive structural changes of silica at 848 K and 1145 K.

Sulfuric acid leaching kinetics of South African chromite

Qing Zhao, Cheng-jun Liu, Pei-yang Shi, Bo Zhang, Mao-fa Jiang, Qing-song Zhang, Ron Zevenhoven, Henrik Saxén

2015, 22(3): 233-240. doi: 10.1007/s12613-015-1066-2

中文摘要(265) PDF(15) SpringerLink

摘要:
The sulfuric acid leaching kinetics of South African chromite was investigated. The negative influence of a solid product layer constituted of a silicon-rich phase and chromium-rich sulfate was eliminated by crushing the chromite and by selecting proper leaching conditions. The dimensionless change in specific surface area and the conversion rate of the chromite were observed to exhibit a proportional relationship. A modified shrinking particle model was developed to account for the change in reactive surface area, and the model was fitted to experimental data. The resulting model was observed to describe experimental findings very well. Kinetics analysis revealed that the leaching process is controlled by a chemical reaction under the employed experimental conditions and the activation energy of the reaction is 48 kJ·mol^-1.

Extracting copper from copper oxide ore by a zwitterionic reagent and dissolution kinetics

Jiu-shuai Deng, Shu-ming Wen, Jian-ying Deng, Dan-dan Wu

2015, 22(3): 241-248. doi: 10.1007/s12613-015-1067-1

中文摘要(297) PDF(9) SpringerLink

摘要:
Sulfamic acid (SA), which possesses a zwitterionic structure, was applied as a leaching reagent for the first time for extracting copper from copper oxide ore. The effects of reaction time, temperature, particle size, reagent concentration, and stirring speed on this leaching were studied. The dissolution kinetics of malachite was illustrated with a three-dimensional diffusion model. A novel leaching effect of SA on malachite was eventually demonstrated. The leaching rate increased with decreasing particle size and increasing concentration, reaction temperature and stirring speed. The activation energy for SA leaching malachite was 33.23 kJ/mol. Furthermore, the effectiveness of SA as a new reagent for extracting copper from copper oxide ore was confirmed by experiment. This approach may provide a solution suitable for subsequent electrowinning. In addition, results reported herein may provide basic data that enable the leaching of other carbonate minerals of copper, zinc, cobalt and so on in an SA system.

Mass transfer of phosphorus in high-phosphorus hot-metal refining

Jiang Diao, Xuan Liu, Tao Zhang, Bing Xie

2015, 22(3): 249-253. doi: 10.1007/s12613-015-1068-0

中文摘要(281) PDF(10) SpringerLink

摘要:
Mass transfer of phosphorus in high-phosphorus hot-metal refining was investigated using CaO-Fe_tO-SiO₂ slags at 1623 K. Based on a two-film theory kinetic model and experimental results, it was found that the overall mass transfer coefficient, which includes the effects of mass transfer in both the slag phase and metal phase, is in the range of 0.0047 to 0.0240 cm/s. With the addition of a small amount of fluxing agents Al₂O₃ or Na₂O into the slag, the overall mass transfer coefficient has an obvious increase. Silicon content in the hot metal also influences the overall mass transfer coefficient. The overall mass transfer coefficient in the lower[Si] heat is much higher than that in the higher[Si] heat. It is concluded that both fluxing agents and lower[Si] hot metal facilitate mass transfer of phosphorus in liquid phases. Furthermore, the addition of Na₂O could also prevent rephosphorization at the end of the experiment.

Effect of microstructure on the low temperature toughness of high strength pipeline steels

Yan-ping Zeng, Peng-yu Zhu, Ke Tong

2015, 22(3): 254-261. doi: 10.1007/s12613-015-1069-z

中文摘要(252) PDF(10) SpringerLink

摘要:
Microstructure observations and drop-weight tear test were performed to study the microstructures and mechanical properties of two kinds of industrial X70 and two kinds of industrial X80 grade pipeline steels. The effective grain size and the fraction of high angle grain boundaries in the pipeline steels were investigated by electron backscatter diffraction analysis. It is found that the low temperature toughness of the pipeline steels depends not only on the effective grain size, but also on other microstructural factors such as martensite-austenite (MA) constituents and precipitates. The morphology and size of MA constituents significantly affect the mechanical properties of the pipeline steels. Nubby MA constituents with large size have significant negative effects on the toughness, while smaller granular MA constituents have less harmful effects. Similarly, larger Ti-rich nitrides with sharp corners have a strongly negative effect on the toughness, while fine, spherical Nb-rich carbides have a less deleterious effect. The low temperature toughness of the steels is independent of the fraction of high angle grain boundaries.

Influence of original microstructure on the transformation behavior and mechanical properties of ultra-high-strength TRIP-aided steel

Hong-xiang Yin, Ai-min Zhao, Zheng-zhi Zhao, Xiao Li, Shuang-jiao Li, Han-jiang Hu, Wei-guang Xia

2015, 22(3): 262-271. doi: 10.1007/s12613-015-1070-6

中文摘要(287) PDF(9) SpringerLink

摘要:
The transformation behavior and tensile properties of an ultra-high-strength transformation-induced plasticity (TRIP) steel (0.2C-2.0Si-1.8Mn) were investigated by different heat treatments for automobile applications. The results show that F-TRIP steel, a traditional TRIP steel containing as-cold-rolled ferrite and pearlite as the original microstructure, consists of equiaxed grains of intercritical ferrite surrounded by discrete particles of M/RA and B. In contrast, M-TRIP steel, a modified TRIP-aided steel with martensite as the original microstructure, containing full martensite as the original microstructure is comprised of lath-shaped grains of ferrite separated by lath-shaped martensite/retained austenite and bainite. Most of the austenite in F-TRIP steel is granular, while the austenite in M-TRIP steel is lath-shaped. The volume fraction of the retained austenite as well as its carbon content is lower in F-TRIP steel than in M-TRIP steel, and austenite grains in M-TRIP steel are much finer than those in F-TRIP steel. Therefore, M-TRIP steel was concluded to have a higher austenite stability, resulting in a lower transformation rate and consequently contributing to a higher elongation compared to F-TRIP steel. Work hardening behavior is also discussed for both types of steel.

Microstructural evolution of a heat-treated H23 tool steel

Meilinda Nurbanasari, Panos Tsakiropoulos, Eric J. Palmiere

2015, 22(3): 272-284. doi: 10.1007/s12613-015-1071-5

中文摘要(305) PDF(8) SpringerLink

摘要:
The microstructure and the stability of carbides after heat treatments in an H23 tool steel were investigated. The heat treatments consisted of austenization at two different austenizing temperatures (1100℃ and 1250℃), followed by water quenching and double-aging at 650℃, 750℃, and 800℃ with air cooling between the first and second aging treatments. Martensite did not form in the as-quenched microstructures, which consisted of a ferrite matrix, M₆C, M₇C₃, and MC carbides. The double-aged microstructures consisted of a ferrite matrix and MC, M₆C, M₇C₃, and M₂₃C₆ carbides. Secondary hardening as a consequence of secondary precipitation of fine M₂C carbides did not occur. There was disagreement between the experimental microstructure and the results of thermodynamic calculations. The highest double-aged hardness of the H23 tool steel was 448 HV after austenization at 1250℃ and double-aging at 650℃, which suggested that this tool steel should be used at temperatures below 650℃.

Influence of ECAP on the fatigue behavior of age-hardenable 2xxx aluminum alloy

M. Namdar, S. A. Jenabali Jahromi

2015, 22(3): 285-291. doi: 10.1007/s12613-015-1072-4

中文摘要(305) PDF(11) SpringerLink

摘要:
The fatigue behavior under load control and the mechanical properties of commercial 2011 aluminum as an age-hardenable Al alloy was studied. To estimate the effects of the equal channel angular pressing (ECAP) process, solution heat treatments, and aging on the fatigue life, tests were conducted at four different stages:furnace cooling; furnace cooling plus one ECAP pass; solid solution heat treatment, quenching, one ECAP pass plus aging at peak age level; and the T6 condition. Only one pass was possible at room temperature because of the high strength of the material. The fracture surface morphology and microstructure after fatigue were evaluated by scanning electron microscopy (SEM). The experimental results revealed that the optimum fatigue life under load control, the tensile strength, and the Vickers hardness of the material were interdependent. The optimum fatigue life under load control was achieved by increasing the tensile strength and hardness of the material.

Microtextural evolution of different TRC AA8006 alloy sections with homogenization

Zhong-wei Chen, Long-fei Shen, Jing Zhao

2015, 22(3): 292-301. doi: 10.1007/s12613-015-1073-3

中文摘要(320) PDF(8) SpringerLink

摘要:
Grain microtexture evolution in twin-roll cast AA8006 alloy sheets subjected to different treatments was investigated using electron backscatter diffraction. The textures of rolling-transverse and normal-transverse sections were characterized in original as-cast twin-roll casting and cold-rolled samples as well as samples homogenized at 500℃ for 8 h and at 580℃ for 4 h. It is found that grains on both the rolling-transverse and normal-transverse sections of cold-rolled samples are made finer by rolling deformation and coarsened after homogenization. Annealing temperature has a stronger effect on the microstructural evolution than annealing time. The grain growth direction is parallel to the normal-transverse section, while grain deformation is more stable on the rolling direction than on the normal direction. The rolling orientations display more obvious anisotropy on the normal-transverse sections than on the rolling-transverse sections. Grain recrystallization and growth occur much easier on the normal-transverse section than on the rolling-transverse section for samples homogenized at 500℃ for 8 h. A special misorientation relationship between cold deformation texture, such as S orientation {123}<634> and cube orientation <110>‖X_axis[cubic], and recrystallization texture after homogenization, such as R orientation {124}<211> and P orientation {011}<122>, is observed.

Evolution of insoluble eutectic Si particles in anodic oxidation films during adipic-sulfuric acid anodizing processes of ZL114A aluminum alloys

Lei Hua, Jian-hua Liu, Song-mei Li, Mei Yu, Lei Wang, Yong-xin Cui

2015, 22(3): 302-308. doi: 10.1007/s12613-015-1074-2

中文摘要(227) PDF(7) SpringerLink

摘要:
The effects of insoluble eutectic Si particles on the growth of anodic oxide films on ZL114A aluminum alloy substrates were investigated by optical microscopy (OM) and scanning electron microscopy (SEM). The anodic oxidation was performed at 25℃ and a constant voltage of 15 V in a solution containing 50 g/L sulfuric acid and 10 g/L adipic acid. The thickness of the formed anodic oxidation film was approximately 7.13 μm. The interpore distance and the diameters of the major pores in the porous layer of the film were within the approximate ranges of 10-20 nm and 5-10 nm, respectively. Insoluble eutectic Si particles strongly influenced the morphology of the anodic oxidation films. The anodic oxidation films exhibited minimal defects and a uniform thickness on the ZL114A substrates; in contrast, when the front of the oxide oxidation films encountered eutectic Si particles, defects such as pits and non-uniform thickness were observed, and pits were observed in the films.

Investigation on the interface of Cu/Al couples during isothermal heating

Yan-qiu Han, Li-hua Ben, Jin-jin Yao, Shu-wei Feng, Chun-jing Wu

2015, 22(3): 309-318. doi: 10.1007/s12613-015-1075-1

中文摘要(235) PDF(8) SpringerLink

摘要:
The evolutionary process and intermetallic compounds of Cu/Al couples during isothermal heating at a constant bonding temperature of 550℃ were investigated in this paper. The interfacial morphologies and microstructures were examined by optical microscopy, scanning electron microscopy equipped with energy dispersive X-ray spectroscopy, and X-ray diffraction. The results suggest that bonding is not achieved between Cu and Al at 550℃ in 10 min due to undamaged oxide films. Upon increasing the bonding time from 15 to 25 min, however, metallurgical bonding is obtained in these samples, and the thickness of the reactive zone varies with holding time. In the interfacial region, the final microstructure consists of Cu₉Al₄, CuAl, CuAl₂, and α-Al + CuAl₂. Furthermore, these results provide new insights into the mechanism of the interfacial reaction between Cu and Al. Microhardness measurements show that the chemical composition exerts a significant influence on the mechanical properties of Cu/Al couples.

Nitridation of chromium powder in ammonia atmosphere

Ling Li, Qiang Zhen, Rong Li

2015, 22(3): 319-324. doi: 10.1007/s12613-015-1076-0

中文摘要(246) PDF(9) SpringerLink

摘要:
CrN powder was synthesized by nitriding Cr metal in ammonia gas flow, and its chemical reaction mechanism and nitridation process were studied. Through thermodynamic calculations, the Cr-N-O predominance diagrams were constructed for different temperatures. Chromium nitride formed at 7002-1200℃ under relatively higher nitrogen and lower oxygen partial pressures. Phases in the products were then investigated using X-ray diffraction (XRD), and the Cr₂N content varied with reaction temperature and holding time. The results indicate that the Cr metal powder nitridation process can be explained by a diffusion model. Further, Cr₂N formed as an intermediate product because of an incomplete reaction, which was observed by high-resolution transmission electron microscopy (HRTEM). After nitriding at 1000℃ for 20 h, CrN powder with an average grain size of 63 nm was obtained, and the obtained sample was analyzed by using a scanning electron microscope (SEM).

Synthesis of steel slag ceramics: chemical composition and crystalline phases of raw materials

Li-hua Zhao, Wei Wei, Hao Bai, Xu Zhang, Da-qiang Cang

2015, 22(3): 325-333. doi: 10.1007/s12613-015-1077-z

中文摘要(289) PDF(9) SpringerLink

摘要:
Two types of porcelain tiles with steel slag as the main raw material (steel slag ceramics) were synthesized based on the CaO-Al₂O₃-SiO₂ and CaO-MgO-SiO₂ systems, and their bending strengths up to 53.47 MPa and 99.84 MPa, respectively, were obtained. The presence of anorthite, α-quartz, magnetite, and pyroxene crystals (augite and diopside) in the steel slag ceramics were very different from the composition of traditional ceramics. X-ray diffraction (XRD) and electron probe X-ray microanalysis (EPMA) results illustrated that the addition of steel slag reduced the temperature of extensive liquid generation and further decreased the firing temperature. The considerable contents of glass-modifying oxide liquids with rather low viscosities at high temperature in the steel slag ceramic adobes promoted element diffusion and crystallization. The results of this study demonstrated a new approach for extensive and effective recycling of steel slag.

留言板

2015年第22卷第3期

视频展示更多>

期刊特色

期刊荣誉更多>

友情链接更多>

留言板

2015年 第22卷 第3期

视频展示更多>

期刊特色

期刊荣誉更多>

友情链接更多>

2015年第22卷第3期