International Journal of Minerals, Metallurgy and Materials

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Study on gold concentrate leaching by iodine-iodide

Hai-xia Wang, Chun-bao Sun, Shao-ying Li, Ping-feng Fu, Yu-guo Song, Liang Li, Wen-qing Xie

2013, 20(4): 323-328. doi: 10.1007/s12613-013-0730-7

中文摘要(336) PDF(17) SpringerLink

摘要:
Gold extraction by iodine-iodide solution is an effective and environment-friendly method. In this study, the method using iodine-iodide for gold leaching is proved feasible through thermodynamic calculation. At the same time, experiments on flotation gold concentrates were carried out and encouraging results were obtained. Through optimizing the technological conditions, the attained high gold leaching rate is more than 85%. The optimum process conditions at 25℃ are shown as follows: the initial iodine concentration is 1.0%, the iodine-to-iodide mole ratio is 1:8, the solution pH value is 7, the liquid-to-solid mass ratio is 4:1, the leaching time is 4 h, the stirring intensity is 200 r/mim, and the hydrogen peroxide consumption is 1%.

Behavior of fluxed lime iron oxide pellets in hot metal bath during melting and refining

J. Pal, S. Ghorai, M. C. Goswami, D. Ghosh, D. Bandyopadhyay, S. Ghosh

2013, 20(4): 329-337. doi: 10.1007/s12613-013-0731-6

中文摘要(313) PDF(10) SpringerLink

摘要:
Lump lime as a flux material in a basic oxygen furnace (BOF) often creates problems in operation due to its high melting point, poor dissolution property, hygroscopic nature, and fines generation tendency. To alleviate these problems, fluxed lime iron oxide pellets (FLIP) containing 30% CaO were developed in this study using waste iron oxide fines and lime. The suitable handling strengths of the pellet (crushing strength: 300 N; drop strength: 130 times) of FLIP were developed by treating with CO₂ or industrial waste gas at room temperature, while no separate binders were used. When the pellet was added into hot metal bath (carbon-containing molten iron), it was decomposed, melted, and transformed to produce low melting oxidizing slag, because it is a combination of main CaO and Fe₂O₃. This slag is suitable for facilitating P and C removal in refining. Furthermore, the pellet enhances waste utilization and use of CO₂ in waste gas. In this article, emphasis is given on studying the behavior of these pellets in hot metal bath during melting and refining along with thermodynamics and kinetics analysis. The observed behaviors of the pellet in hot metal bath confirm that it is suitable and beneficial for use in BOF and replaces lump lime.

Effects of CeO₂ on the XPS valence band spectra of coal under the combustion initialization stage at 400℃

Cheng-lin Qi, Jian-liang Zhang, Chao Ma, Gen-sheng Feng, Zhong-ping Song

2013, 20(4): 338-344. doi: 10.1007/s12613-013-0732-5

中文摘要(365) PDF(14) SpringerLink

摘要:
In order to get the catalytic mechanism of CeO₂ on graphite and coal at 400℃, the morphologies of coal, graphite, and CeO₂ before and after combustion were analyzed through X-ray photoelectron spectroscopy (XPS). It is found that the particle size of coal is mostly between 11.727 and 64.79 μm, while the particle size of CeO₂ is between 1.937 and 11.79 μm. The agglomeration of coal and CeO₂ can be seen by scanning electron microscopy (SEM) after reaction. XPS results show that with the addition of CeO₂, the intensity of binding energy gets stronger, but there is no energy peak transition. Comparing the character of coal with and without the addition of CeO₂, it can be seen that the C-C bond fractures first at 400℃, while the C-H energy-band takes electrons at the same time to be far away from the Fermi level, and the O 2s, O 2p, and C sp hybrid orbitals are all excited. Adding CeO₂ can enhance the activity of the whole coal. In addition, through XPS analysis, combined with the oxygen transfer theory and the electron transfer theory, the catalytic mechanism of CeO₂ for pulverized coal combustion could be obtained.

Study on the early warning mechanism for the security of blast furnace hearths

Hong-bo Zhao, Shou-feng Huo, Shu-sen Cheng

2013, 20(4): 345-353. doi: 10.1007/s12613-013-0733-4

中文摘要(348) PDF(11) SpringerLink

摘要:
The campaign life of blast furnace (BF) hearths has become the limiting factor for safety and high efficiency production of modern BFs. However, the early warning mechanism of hearth security has not been clear. In this article, based on heat transfer calculations, heat flux and erosion monitoring, the features of heat flux and erosion were analyzed and compared among different types of hearths. The primary detecting elements, mathematical models, evaluating standards, and warning methods were discussed. A novel early warning mechanism with the three-level quantificational standards was proposed for BF hearth security.

Evaluation and modification of inclusion characteristics in HK40 heatresistant cast steel

Ali Navaei, Reza Eslami-Farsani, Majid Abbasi

2013, 20(4): 354-359. doi: 10.1007/s12613-013-0734-3

中文摘要(259) PDF(9) SpringerLink

摘要:
Specifications of inclusions such as the type, morphology, number, composition, size, and place of inclusions in HK40 heat-resistant casting steel were studied by optical microscopy and scanning electron microscopy equipped with an energy-dispersive spectroscopy system. The effects of calcium silicide (CaSi) addition on these characteristics were evaluated at two pouring temperatures of 1420℃ and 1470℃. It was found that most of the appeared inclusions were in the type of chromium oxide. CaSi addition had a significant effect on the morphological modification, size and distribution of inclusions as well as changing the composition to oxide-sulfide compounds.

Effects of the shape and size of rectangular inclusions on the fatigue cracking behavior of ultra-high strength steels

Yan-ping Zeng, Hong-mei Fan, Xi-shan Xie

2013, 20(4): 360-364. doi: 10.1007/s12613-013-0735-2

中文摘要(284) PDF(12) SpringerLink

摘要:
The fatigue cracking behavior of ultra-high strength steels containing rectangular inclusions of small sizes were investigated based on in situ observations by scanning electron microscopy (SEM). The size and shape of rectangular inclusions affect markedly the initiation site and propagation path of a fatigue crack. Especially, the initiation site of a fatigue crack depends strongly on the angle between the long-axis of a rectangle inclusion and the loading direction, and the length/width ratio of this rectangle inclusion because the residual stress distribution fields vary with these conditions. The results coincide very well with those of finite element analysis.

Brazing 6061 aluminum alloy with Al-Si-Zn filler metals containing Sr

Wei Dai, Song-bai Xue, Feng Ji, Jiang Lou, Bo Sun, Shui-qing Wang

2013, 20(4): 365-370. doi: 10.1007/s12613-013-0736-1

中文摘要(247) PDF(9) SpringerLink

摘要:
Al-6.5Si-42Zn and Al-6.5Si-42Zn-0.09Sr filler metals were used for brazing 6061 aluminum alloy. Air cooling and water cooling were applied after brazing. Si phase morphologies in the brazing alloy and the brazed joints were investigated. It was found that zinc in the Al-Si filler metals could reduce the formation of eutectic Al-Si phase and lower the brazing temperature at about 520℃. Adding 0.09wt% Sr element into the Al-6.5Si-42Zn alloy caused α-Al phase refinement and transformed acicular Si phase into the finely fiber-like. After water cooling, Zn element dissolved into the Al-Si eutectic area, and η-Zn phase disappeared in the brazed joints. Tensile strength testing results showed that the Sr-modified filler metal could enhance the strength of the brazed joints by 13% than Al-12Si, while water-cooling further improved the strength at 144 MPa.

Formation and properties of high Fe-content Fe-(B-Si)-Zr bulk amorphous alloys

Yao-xiang Geng, Ying-min Wang, Jian-bing Qiang, Qing Wang, Fan-yang Kong, Gui-feng Zhang, Chuang Dong

2013, 20(4): 371-374. doi: 10.1007/s12613-013-0737-0

中文摘要(236) PDF(7) SpringerLink

摘要:
The present work is devoted to the development of Fe-(B-Si)-Zr amorphous alloys with high glass-forming ability and good magnetic properties. Using the cluster-plus-glue-atom model proposed for ideal amorphous structures, [FeFe₁₁B₃Si](Fe_1−xZr_x) was determined as the cluster formula of Fe-(B-Si)-Zr alloys. The glass formation and thermal stability of the serial alloys, namely, [FeFe₁₁B₃Si](Fe_1−xZr_x) (x = 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.75, and 1.0), were studied by the combination of copper mold casting, X-ray diffraction, and differential thermal analysis techniques. The maxima of glass-forming ability and thermal stability were found to occur at the compositions of [FeFe₁₁B₃Si](Fe_0.6Zr_0.4) and [FeFe₁₁B₃Si](Fe_0.5Zr_0.5). The alloys can be cast into amorphous rods with 1.5 mm diameter, and upon reheating, the amorphous alloys exhibit a large undercooled liquid span of 37 K. The saturation magnetization of the [FeFe₁₁B₃Si](Fe_0.5Zr_0.5) amorphous alloy was measured to be 1.4 T.

Frequency dependence of magnetization and giant magneto impedance effect of amorphous wires

Shu-ling Zhang, Jian-fei Sun, Da-wei Xing, Da-qing Fang, Lu-cai Wang

2013, 20(4): 375-378. doi: 10.1007/s12613-013-0738-z

中文摘要(230) PDF(9) SpringerLink

摘要:
The frequency dependence of magnetization process and giant magneto impedance (GMI) effect of Co-rich melt-extracted amorphous wires was studied by Kerr effect and impedance analyzer, respectively. It is demonstrated that the transverse Kerr intensity and the corresponding GMI response increase with increasing frequency, which contributes to the upgraded skin effect. However, the skin depth has a slothful trend with frequency when it is up to the megahertz range, which gives rise to the transformation of magnetization. The process is much more sensitive to the direct current magnetic field and the sensitive change of the circular permeability, and GMI response is observed as its consequence. This proves that the evolution of circumferential magnetization and the corresponding permeability with the direct current magnetic field is the essence of GMI response, and a much more sensitive magnetization promises a better GMI response.

Thermodynamic analysis and formula optimization of steel slag-based ceramic materials by FACTsage software

Xian-bin Ai, Hao Bai, Li-hua Zhao, Da-qiang Cang, Qi Tang

2013, 20(4): 379-385. doi: 10.1007/s12613-013-0739-y

中文摘要(240) PDF(9) SpringerLink

摘要:
Using steel slag as a main raw material of ceramics is considered as a high value-added way. However, the relationship among the initial composition, ceramic microstructure, and macroscopic properties requires further study. In this paper, a series of ceramics with different slag ratios (0–70wt%) were designed, and the software FACTsage was introduced to simulate the formation of crystalline phases. The simulation results indicate that mullite is generated but drastically reduced at the slag ratios of 0–25wt%, and anorthite is the dominant crystalline phase in the slag content of 25wt%-45wt%. When the slag ratio is above 45wt%, pyroxene is generated more than anorthite. This is because increasing magnesium can promote the formation of pyroxene. Then, the formula with a slag content of 40wt% was selected and optimized. X-ray diffraction results were good consistent with the simulation results. Finally, the water absorption and bending strength of optimized samples were measured.

Dendritic and spherical crystal reinforced metallic glass matrix composites

Jun-wei Qiao, Yong Zhang, Hui-jun Yang, Sheng-bo Sang

2013, 20(4): 386-392. doi: 10.1007/s12613-013-0740-5

中文摘要(220) PDF(7) SpringerLink

摘要:
Zr-based bulk metallic glass matrix composites (BMGMCs) with a composition of Zr_60.0Ti_14.7Nb_5.3Cu_5.6Ni_4.4Be_10.0 (at%) were fabricated by an innovative process, i.e., semisolid processing plus Bridgman solidification. Different morphologies, distributions, and volume fractions of the crystalline phases can be achieved by tailoring the withdrawal velocity. The largest fracture strain of Zr_60.0Ti_14.7Nb_5.3Cu_5.6Ni_4.4Be_10.0(at%) composites with the withdrawal velocity of 1.0 mm/s was found to be 16.7%. The mechanism of plasticity improvement is mainly attributed to the interpenetrated structure of the crystalline phase, which greatly confines the rapid propagation of shear bands.

InAsSb thick epilayers applied to long wavelength photoconductors

Yu-zhu Gao, Xiu-ying Gong, Guang-hui Wu, Yan-bin Feng, Takamitsu Makino, Hirofumi Kan, Tadanobu Koyama, Yasuhiro Hayakawa

2013, 20(4): 393-396. doi: 10.1007/s12613-013-0741-4

中文摘要(272) PDF(7) SpringerLink

摘要:
InAs_0.052Sb_0.948 epilayers with cutoff wavelengths longer than 8 μm were successfully grown on InAs substrates using melt epitaxy (ME). Scanning electron microscopy observations show that the interface between the epilayers and substrates is flat, indicating the good quality of the epilayers, and the thickness of the epilayers is 40 μm. Photoconductors were fabricated using InAs_0.052Sb_0.948 thick epilayers grown by ME. Ge optical lenses were set on the photoconductors. At room temperature, the photoresponse wavelength range was 2–10 μm. The peak detectivity D_λp^* reached 5.4 × 10⁹ cm·Hz^1/2·W⁻¹ for the immersed detectors. The detectivity D^* was 9.3 × 10⁸ and 1.3 × 10⁸ cm·Hz^1/2·W⁻¹ at the wavelength of 8 and 9 μm, respectively. The good performance of the uncooled InAsSb detectors was experimentally validated.

Mechanical properties of TiO₂-hydroxyapatite nanostructured coatings on Ti-6Al-4V substrates by APS method

Mohammad Zakeri, Elmira Hasani, Morteza Tamizifar

2013, 20(4): 397-402. doi: 10.1007/s12613-013-0742-3

中文摘要(272) PDF(9) SpringerLink

摘要:
TiO₂-hydroxyapatite (HA) nanostructured coatings were produced by atmospheric plasma spray method. The effects of starting powder composition and grain size on their mechanical properties were investigated. The microstructure and morphology were characterized by X-ray diffraction and scanning electron microscopy (SEM). It is found that the coating with 10% HA has the best mechanical properties. Based on Rietveld refinement method, the mean grain size of the as-received powder (212 nm) extensively decreases to 66.4 nm after 20 h of high-energy ball milling. In spite of grain growth, the deposited coatings maintain their nanostructures with the mean grain size of 112 nm. SEM images show that there is a lower porosity in the coating with a higher HA content. Optical microscopy images show that uniform thickness is obtained for all the coatings.

Preparation, characterization, and antibacterial activity of γ-irradiated silver nanoparticles in aqueous gelatin

Majid Darroudi, Mansor B. Ahmad, Mohammad Hakimi, Reza Zamiri, Ali Khorsand Zak, Hasan Ali Hosseini, Mohsen Zargar

2013, 20(4): 403-409. doi: 10.1007/s12613-013-0743-2

中文摘要(282) PDF(10) SpringerLink

摘要:
Colloidal silver nanoparticles (Ag-NPs) were obtained through γ-irradiation of aqueous solutions containing AgNO₃ and gelatin as a silver source and stabilizer, respectively. The absorbed dose of γ-irradiation influences the particle diameter of the Ag-NPs, as evidenced from surface plasmon resonance (SPR) and transmission electron microscopy (TEM) images. When the γ-irradiation dose was increased (from 2 to 50 kGy), the mean particle size was decreased continuously as a result of γ-induced Ag-NPs fragmentation. The antibacterial properties of the Ag-NPs were tested against Methicillinresistant Staphylococcus aureus (MRSA) (Gram-positive) and Pseudomonas aeruginosa (P.a) (Gram-negative) bacteria. This approach reveals that the γ-irradiation-mediated method is a promising simple route for synthesizing highly stable Ag-NPs in aqueous solutions with good antibacterial properties for different applications.

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2013年第20卷第4期