International Journal of Minerals, Metallurgy and Materials

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Mineralogy and carbothermal reduction behaviour of vanadium-bearing titaniferous magnetite ore in Eastern India

Saikat Samanta, Manik Chandra Goswami, Tapan Kumar Baidya, Siddhartha Mukherjee, Rajib Dey

2013, 20(10): 917-924. doi: 10.1007/s12613-013-0815-3

中文摘要(290) PDF(9) SpringerLink

摘要:
Vanadium-bearing titaniferous magnetite bands hosted by Precambrian gabbro-norite-anorthositic rocks or their metamorphic equivalents were discovered in some parts of Eastern Indian Shield, containing 48%–49% Fe (total), 10%–25% TiO₂, and 0.3%–2.20% V₂O₅ by mass. Mineralogical and petrological study, composition, and characterization of the vanadium-bearing titaniferous magnetite ore were carried out by scanning electron microscopy-energy dispersive X-ray (SEM-EDX), wave length X-ray florescence (WDXRF), inductively coupled plasma-atomic emission spectroscopy (ICP-AES), X-ray diffraction (XRD), etc. Chemical beneficiation for valuable metals, such as Fe, Ti, and V, was performed by reduction roasting. The direct and indirect reduction were investigated by mixing the lump ore with solid activated charcoal in a closed reactor and purging the reducing gas mixture in standard reducibility index apparatus at different temperatures and time intervals. The reduction roasting parameters were optimized. Finally, the reduced samples were crushed and upgraded by magnetic separation. The results show that, the maximum mass fractions of magnetic and nonmagnetic parts achieved are 69.36% and 30.64%, respectively, which contain 10.6% TiO₂ and 0.84% V₂O₅ in the magnetic part and 36.5% TiO₂ and 0.22% V₂O₅ in the nonmagnetic part.

Biodesulfurization of vanadium-bearing titanomagnetite concentrates and pH control of bioleaching solution

Xiao-rong Liu, Sheng-cai Jiang, Yan-jun Liu, Hui Li, Hua-jun Wang

2013, 20(10): 925-930. doi: 10.1007/s12613-013-0816-2

中文摘要(183) PDF(7) SpringerLink

摘要:
Vanadium-bearing titanomagnetite concentrates were desulfurized with Acidithiobacillus ferrooxidans (A. ferrooxidans). The sulfur content of the concentrates was reduced from 0.69wt% to 0.14wt% after bioleaching for 15 d with a 10% pulp density at 30℃. Maintaining a stable pH value during biodesulfurization was critical because of high acid consumption, resulting from a combination of nonoxidative and oxidative dissolution of pyrrhotite in acid solution. It is discovered that the citric acid-disodium hydrogen phosphate buffer of pH 2.0 can control the solution pH value smoothly in the optimal range of 2.0–3.0 for A. ferrooxidans growth. Using the buffer in the volume fraction range of 5.0%–15.0% stimulates A. ferrooxidans growth and improves the biodesulfurization efficiency. Compared with the buffer-free control case, the maximum increase of biodesulfurization rate is 29.7% using a 10.0vol% buffer. Bioleaching provides an alternative process for desulfurization of vanadium-bearing titanomagnetite ores.

Carbothermal reduction process of the Fe-Cr-O system

Yan-ling Zhang, Yang Liu, Wen-jie Wei

2013, 20(10): 931-940. doi: 10.1007/s12613-013-0817-1

中文摘要(298) PDF(11) SpringerLink

摘要:
Understanding the reduction behaviors and characteristics of the end products of Fe-Cr-O systems is very important not only for maximizing the recovery of metals from stainless steel dust but also for the subsequent reuse in metallurgical process. The present work first predicted the possible products thermodynamically when FeCr₂O₄ was reduced by C. The reduction behaviors by graphite of three kinds of Fe-Cr-O systems, i.e., FeCr₂O₄, Fe₂O₃+Cr₂O₃, and Fe+Cr₂O₃, were then investigated in 1350–1550℃. Further, the microstructures of final products and element distribution conditions were examined. The results suggest that, thermodynamically, the mass of products for the carbothermal reduction of FeCr₂O₄ is a strong function of temperature, and the initial carbon content is used. More Fe-Cr-C solution and less residual carbon content are obtained at higher temperatures and lower n_C:n_O ratios (the initial molar ratio of C to O in the sample). Experimental data show that the sample amount tends to affect the reduction rate, and the residual carbon content strongly depends on n_C:n_O. With regard to the phases present in products during the reaction process, metal carbides tend to form in the initial stage, whereas Fe-Cr-C solution forms when the degree of reduction is sufficiently high.

Recycle of valuable products from oily cold rolling mill sludge

Bo Liu, Shen-gen Zhang, Jian-jun Tian, De-an Pan, Yang Liu, Alex A. Volinsky

2013, 20(10): 941-946. doi: 10.1007/s12613-013-0818-0

中文摘要(295) PDF(10) SpringerLink

摘要:
Oily cold rolling mill (CRM) sludge contains lots of iron and alloying elements along with plenty of hazardous organic components, which makes it as an attractive secondary source and an environmental contaminant at the same time. The compound methods of “vacuum distillation + oxidizing roasting” and “vacuum distillation + hydrogen reduction” were employed for the recycle of oily cold rolling mill sludge. First, the sludge was dynamically vacuum distilled in a rotating furnace at 50 r/min and 600℃ for 3 h, which removed almost hazardous organic components, obtaining 89.2wt% ferrous resultant. Then, high purity ferric oxide powders (99.2wt%) and reduced iron powders (98.9wt%) were obtained when the distillation residues were oxidized and reduced, respectively. The distillation oil can be used for fuel or chemical feedstock, and the distillation gases can be collected and reused as a fuel.

Rapid recovery of polycrystalline silicon from kerf loss slurry using double-layer organic solvent sedimentation method

Peng-fei Xing, Jing Guo, Yan-xin Zhuang, Feng Li, Gan-feng Tu

2013, 20(10): 947-952. doi: 10.1007/s12613-013-0819-z

中文摘要(290) PDF(14) SpringerLink

摘要:

The rapid development of photovoltaic (PV) industries has led to a shortage of silicon feedstock. However, more than 40% silicon goes into slurry wastes due to the kerf loss in the wafer slicing process. To effectively recycle polycrystalline silicon from the kerf loss slurry, an innovative double-layer organic solvent sedimentation process was presented in the paper. The sedimentation velocities of Si and SiC particles in some organic solvents were investigated. Considering the polarity, viscosity, and density of solvents, the chloroepoxy propane and carbon tetrachloride were selected to separate Si and SiC particles. It is found that Si and SiC particles in the slurry waste can be successfully separated by the double-layer organic solvent sedimentation method, which can greatly reduce the sedimentation time and improve the purity of obtained Si-rich and SiC-rich powders. The obtained Si-rich powders consist of 95.04% Si, and the cast Si ingot has 99.06% Si.

Hot deformation behavior of microstructural constituents in a duplex stainless steel during high-temperature straining

Amir Momeni, Shahab Kazemi, Ali Bahrani

2013, 20(10): 953-960. doi: 10.1007/s12613-013-0820-6

中文摘要(275) PDF(8) SpringerLink

摘要:
The hot deformation characteristics of 1.4462 duplex stainless steel (DSS) were analyzed by considering strain partitioning between austenite and ferrite constituents. The individual behavior of ferrite and austenite in microstructure was studied in an iso-stress condition. Hot compression tests were performed at temperatures of 800–1100℃ and strain rates of 0.001–1 s⁻¹. The flow stress was modeled by a hyperbolic sine constitutive equation, the corresponding constants and apparent activation energies were determined for the studied alloys. The constitutive equation and law of mixture were used to measure the contribution factor of each phase at any given strain. It is found that the contribution factor of ferrite exponentially declines as the Zener-Hollomon parameter (Z) increases. On the contrary, the austenite contribution polynomially increases with the increase of Z. At low Z values below 2.6.×10¹⁵ (lnZ=35.5), a negative contribution factor is determined for austenite that is attributed to dynamic recrystallization. At high Z values, the contribution factor of austenite is about two orders of magnitude greater than that of ferrite, and therefore, austenite can accommodate more strain. Microstructural characterization via electron back-scattered diffraction (EBSD) confirms the mechanical results and shows that austenite recrystallization is possible only at high temperature and low strain rate.

Morphological evolution of tunnel tips for aluminum foils during DC etching

Li-bo Liang, Ye-dong He, Hong-zhou Song, Xiao-fei Yang, Xiao-yu Cai

2013, 20(10): 961-966. doi: 10.1007/s12613-013-0821-5

中文摘要(224) PDF(9) SpringerLink

摘要:
The morphologies of tunnel tips in different stages for aluminum foils during DC etching in 1.5 mol/L HCl solution at 90℃ were observed by field emission scanning electron microscopy (FE-SEM). A novel model was proposed to describe the morphological evolution of tunnel tips throughout the growth processes. In the pit nucleation stage, the pits vary from the hemispherical to half-cubic shapes due to the activation of pit tips from the center to the edge. During the tunnel growth stage, the pits dissolve toward the depth direction and develop into the tunnels, and their tips remain flat. In the tip passivation stage, as the passivation of tunnel tips speeds up from the edge to the center, the tunnel tips change from flat shapes to three-dimensional protrusions. The mechanism may be attributed to the order of activation or passivation on the tunnel tips changed in different stages.

Electrical and mechanical properties of vapour grown gallium monotelluride crystals

P. M. Reshmi, A. G. Kunjomana, K. A. Chandrasekharan

2013, 20(10): 967-971. doi: 10.1007/s12613-013-0822-4

中文摘要(285) PDF(7) SpringerLink

摘要:
The physical vapour deposition (PVD) of gallium monotelluride (GaTe) in different crystalline habits was established in the growth ampoule, strongly depending on the temperature gradient. Proper control on the temperatures of source and growth zones in an indigenously fabricated dual zone furnace could yield the crystals in the form of whiskers and spherulites. Optical and electron microscopic images were examined to predict the growth mechanism of morphologies. The structural parameters of the grown spherulites were determined by X-ray powder diffraction (XRD). The stoichiometric composition of these crystals was confirmed using energy dispersive analysis by X-rays (EDAX). The type and nature of electrical conductivity were identified by the conventional hot probe and two probe methods, respectively. The mechanical parameters, such as Vickers microhardness, work hardening index, and yield strength, were deduced from microindentation measurements. The results show that the vapour grown p-GaTe crystals exhibit novel physical properties, which make them suitable for device applications.

Soft chemical synthesis and luminescence properties of red long-lasting phosphors Y₂O₂S:Sm³⁺

Yan-juan Li, Ming-wen Wang, Lu-dan Zhang, Duo Gao, Shi-xiang Liu

2013, 20(10): 972-977. doi: 10.1007/s12613-013-0823-3

中文摘要(274) PDF(7) SpringerLink

摘要:
Sm³⁺-activated Y₂O₂S red phosphors were prepared by the combustion method and microemulsion method at the first time. X-ray characterization and electron diffraction show that, Y₂O₂S:Sm³⁺, Ti⁴⁺, Mg²⁺ samples prepared by these two methods are pure hexagonal crystals in structure with a trivial change due to dopants. Scanning electron microscopy (SEM) results show that the product presents an almond-like sheet in uniform size. Under the excitation of 269 nm ultraviolet light, Y₂O₂S:Sm³⁺ samples fabricated by these two methods exhibit three main groups of red emission lines located at 564, 604, and 656 nm, respectively, which are attributed to the transitions of 4G_5/2 →6H_5/2, 4G_5/2 →6H_7/2, 4G_5/2 →6H_9/2, respectively. The samples prepared by microemulsion are seven times higher in fluorescent emission intensity and half time longer in afterglow time than that prepared by combustion.

Microstructural and mechanical properties of Al-4.5wt% Cu reinforced with alumina nanoparticles by stir casting method

N. Valibeygloo, R. Azari Khosroshahi, R. Taherzadeh Mousavian

2013, 20(10): 978-985. doi: 10.1007/s12613-013-0824-2

中文摘要(327) PDF(15) SpringerLink

摘要:
The microstructure and mechanical properties of Al-4.5wt% Cu alloy reinforced with different volume fractions (1.5vol%, 3vol%, and 5vol%) of alumina nanoparticles, fabricated using stir casting method, were investigated. Calculated amounts of alumina nanoparticles (about ϕ50 nm in size) were ball-milled with aluminum powders in a planetary ball mill for 5 h, and then the packets of milled powders were incorporated into molten Al-4.5wt% Cu alloy. Microstructural studies of the nanocomposites reveal a uniform distribution of alumina nanoparticles in the Al-4.5wt% Cu matrix. The results indicate an outstanding improvement in compression strength and hardness due to the effect of nanoparticle addition. The aging behavior of the composite is also evaluated, indicating that the addition of alumina nanoparticles can accelerate the aging process of the alloy, resulting in higher peak hardness values.

Properties of a new type Al/Pb-0.3%Ag alloy composite anode for zinc electrowinning

Hai-tao Yang, Huan-rong Liu, Yong-chun Zhang, Bu-ming Chen, Zhong-cheng Guo, Rui-dong Xu

2013, 20(10): 986-993. doi: 10.1007/s12613-013-0825-1

中文摘要(327) PDF(11) SpringerLink

摘要:
An Al/Pb-0.3%Ag alloy composite anode was produced via composite casting. Its electrocatalytic activity for the oxygen evolution reaction and corrosion resistance was evaluated by anodic polarization curves and accelerated corrosion test, respectively. The microscopic morphologies of the anode section and anodic oxidation layer during accelerated corrosion test were obtained by scanning electron microscopy. It is found that the composite anode (hard anodizing) displays a more compact interfacial combination and a better adhesive strength than plating tin. Compared with industrial Pb-0.3%Ag anodes, the oxygen evolution overpotentials of Al/Pb-0.3%Ag alloy (hard anodizing) and Al/Pb-0.3%Ag alloy (plating tin) at 500 A·m⁻² were lower by 57 and 14 mV, respectively. Furthermore, the corrosion rates of Pb-0.3%Ag alloy, Al/Pb-0.3%Ag alloy (hard anodizing), and Al/Pb-0.3%Ag alloy (plating tin) were 13.977, 9.487, and 11.824 g·m⁻²·h⁻¹, respectively, in accelerated corrosion test for 8 h at 2000 A·m⁻². The anodic oxidation layer of Al/Pb-0.3%Ag alloy (hard anodizing) is more compact than Pb-0.3%Ag alloy and Al/Pb-0.3%Ag alloy (plating tin) after the test.

Preparation and anti atomic oxygen erosion properties of OPPOSS/PI composites

Wei-ping Li, Hui-cong Liu, Li-li Feng

2013, 20(10): 994-1000. doi: 10.1007/s12613-013-0826-0

中文摘要(279) PDF(9) SpringerLink

摘要:
Atomic oxygen (AO) found in low earth orbit can cause serious erosion to polyimide (PI) materials, which greatly limits their lifetime. 8-phenyl silsesquioxane (OPPOSS) was synthesized, and OPPOSS/PI composites were prepared by physical blending, followed by thermal imidization to enhance the AO erosion resistance of PI materials. The morphology, composition, and structure of the composites were analyzed before and after AO exposure in a ground simulated facility of atomic oxygen. After 16 h AO exposure, the OPPOSS/PI composite with 5wt% OPPOSS addition shows an erosion rate of about 1.4×10⁻²⁴ cm³/atom with only 48% mass loss of that of PI without OPPOSS addition. The mixture of OPPOSS nano molecules is assembled into a kind of regular square structure and distributed evenly in OPPOSS/PI composites. Some SiO₂ particles are formed in the composites during AO exposure, which can act as “inert points” to reduce the AO erosion rate of OPPOSS/PI composites.

Biodegradable starch/poly (vinyl alcohol) film reinforced with titanium dioxide nanoparticles

Zahra Hejri, Ali Akbar Seifkordi, Ali Ahmadpour, Seyed Mojtaba Zebarjad, Abdolmajid Maskooki

2013, 20(10): 1001-1011. doi: 10.1007/s12613-013-0827-z

中文摘要(356) PDF(20) SpringerLink

摘要:
Biodegradable starch/poly (vinyl alcohol)/nano-titanium dioxide (ST/PVA/nano-TiO₂) nanocomposite films were prepared via a solution casting method. Their biodegradability, mechanical properties, and thermal properties were also studied in this paper. A general full factorial experimental approach was used to determine effective parameters on the mechanical properties of the prepared films. ST/PVA/TiO₂ nanocomposites were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The results of mechanical analysis show that ST/PVA films with higher contents of PVA have much better mechanical properties. In thermal analysis, it is found that the addition of TiO₂ nanoparticles improves the thermal stability of the films. SEM micrographs, taken from the fracture surface of samples, illustrate that the addition of PVA makes the film softer and more flexible. The results of soil burial biodegradation indicate that the biodegradability of ST/PVA/TiO₂ films strongly depends on the starch proportion in the film matrix. The degradation rate is increased by the addition of starch in the films.

Preparation and visible-light photocatalytic property of nanostructured Fe-doped TiO₂ from titanium containing electric furnace molten slag

Yang Li, Yi Yue, Zai-qing Que, Mei Zhang, Min Guo

2013, 20(10): 1012-1020. doi: 10.1007/s12613-013-0828-y

中文摘要(319) PDF(10) SpringerLink

摘要:
Nanostructured Fe-doped titanium dioxide was synthesized from titanium containing electric furnace molten slag (TCEFMS) by using an alkali fusion, followed by a hydrolyzation-acidolysis-calcination route. The effects of alkali/slag mass ratio, calcinating temperature, calcinating time, and water/slag mass ratio on the extraction efficiency and purity of products were systematically studied in this paper. It is indicated that the best extraction efficiency of nanostructured Fedoped titanium dioxide is 99.35%, when the molten slag is calcinated at 700℃ for 1 h with the mass ratio of alkali/molten slag of 1.5:1. The influence of alkali/slag mass ratio on the photocatalytic activity of final products was evaluated by the photodegradation of methyl blue under visible light irradiation. A maximum photodegradation efficiency of 88.12% over 30 min was achieved under the optimum conditions.

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2013年第20卷第10期