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By Senlin Cui, In-ho Jung

Significant amount of commercial aircrafts will be retired in 2020, and the recycling of Al components in such aircrafts becomes an important issue in aerospace and Al industry. Recycling of Al from obsoleted Al products can effectively reduce the energy consumption and CO2 emission which is more economical and ecofriendly. In the present study, thermodynamic analysis for the various recycling technologies of Al alloys were performed based on the comprehensive and accurate thermodynamic database. The recycling technologies reviewed in this work include the vaporization process to reduce Zn, precipitation process to reduce Fe, Mn, Si, Ti, Zr, flux treatment for Al 2O3 and MgO, etc. Several key issues and limitation of the recycling of the aircraft Al were discussed. The recycling technologies discussed can also be utilized to recycle other Al alloys for common usage. All the thermodynamic calculations were performed using the FactSage FTlite database.

Mar 1, 2017

By K. Adham, T. Buchholz

Debottlenecking of high temperature processes within an existing metallurgical plant can significantly increase the throughput to meet new production demands. Modeling and simulation can help to fulfil that aim through incremental changes and operational improvements, rather than the more expensive option of building new plants and facing new environmental and infrastructure challenges. This paper describes a methodology of how modeling tools can be used to simulate the processing steps, how to estimate their existing and ultimate capacities, and how to determine the minimum cost points for a plant capacity expansion. This technique is presented through a generic description that can be applied to different metallurgical processing studies. We start with heat-and-mass balances, draw a bottleneck diagram, brainstorm capacity increase options, and prepare a cost-capacity curve. Hatch has successfully applied this technique to a number of plant capacity studies, with great benefits to our industrial clients (Adhametal et al. in A Success Path from Process R&D to Commercial Plants, Montreal, Canada, [1]).

Mar 1, 2017

By Wenqiang Bao, Qijie Zhai, Ting Wang, Shaobo Zheng, Huigai Li

The type of inclusions with different sizes in as-cast low carbon steel strip which is deoxidized by Si–Mn has been characterized by scanning electron microscope (SEM) and transmission electron microscopy (TEM). SEM observation and analysis suggested that the type of inclusions larger than 1 μm is manganese silicate. TEM analysis was carried out to investigate the composition and structure of nano-inclusions. Inclusions with diameter about 100 nm are manganese silicate, MnS–Si(Mn)Ox complex particles and isolated cubic Al2O3. Furthermore, HREM observations have revealed that there were two kinds of ultrafine particles in size range of 5–10 nm. One is spherical monoclinic Cu2S; the other is silicon-iron oxide particles with morphology of long strip. In addition, some thermodynamic calculations were performed to explain the corresponding relation between the type of inclusions and their size.

Mar 1, 2017

By Gökhan Hardal, Berat Yüksel Price

Nickel manganite based negative temperature coefficient (NTC) thermistors have good temperature sensor characteristics and electrical stability for temperature measurement applications. In this study, the electrical and microstructural properties of Ni0.5Co0.5Cu0.3Zn0.3Mn1.4O4 NTC thermistor were investigated. The samples were fabricated by the conventional solid-state reaction method. The powders were calcinated at 900 °C for 2 h and the samples were sintered at 1200 and 1300 °C for 5 h in air. The bulk density of samples was 5.07 and 4.96 g/cm3, respectively. The microstructure of samples was observed using a scanning electron microscope. The electrical resistance was measured in a temperature programmable furnace between 25 and 85 °C. The electrical resistivity of the Ni0.5Co0.5Cu0.3Zn0.3Mn1.4O4 sample increased from 52 Ω cm to 95 Ω cm when the sintering temperature increased from 1200 to 1300 °C. The material constant “B”, sensitivity coefficient “α” and activation energy “Ea” values were also calculated for the NTC thermistors.

Mar 1, 2017

By Xinzhong Deng, Naixiang Feng, Kejia Liu, Jianping Peng, Yaowu Wang, Yi Zhang, Yuezhong Di

Low-carbon Ti2O3 was prepared by carbonthermal reduction of the mixture of titanium dioxide and activated carbon at vacuum condition. The kinetics and phase evolution of Ti2O3 formation process were investigated through X-ray diffraction and gravimetric analysis. The only intermediate phase detected is Ti3O5. The reduction time was reduced sharply to 4 h when temperature was raised to 1300 °C. The best molar ratio of activated carbon and TiO2 is 0.6–1. At this condition, the content of Ti2O3 in slag is up to 95.63% and the content of the carbon element is below 0.004%, which meets the requirements for the further preparation of metal Ti by FFC Cambridge process. At the same time, the microstructure of Ti2O3 generated presented porosity, which would promote the electro-deoxidation process extremely.

Mar 1, 2017

By Hui-gang Wang, Mei Zhang, Min Guo

Metal-doped Ni–Zn ferrite with spinel structure was directly synthesized from treated zinc-containing electric arc furnace dust (Zn-containing EAFD) by solid state reaction method, realizing the transformation of Zn-containing EAFD from solid waste to high value-added material. A certain mass of NiCl26H2O was added to the treated Zn-containing EAFD before calcination. Then the effects of the mass ratio of treated Zn-containing EAFD to NiCl26H2O (RTZE/N, g g−1) and calcination temperature on the synthesis and magnetic properties of as-synthesized samples were systematically investigated by X-ray Diffraction, Raman Spectroscopy and Physical Property Measurement System. It is indicated that RTZE/N and calcination temperature had important influences on the synthesis of single-phase spinel ferrite and their magnetic properties. Pure metal-doped Ni–Zn ferrite, which exhibited good magnetic properties of higher saturation magnetization (Ms, 60.5 emu g−1) and lower coercivity (Hc, 49.8 Oe), was obtained when the calcination temperature was controlled at 1100 °C for 2 h with RTZE/N of 1:0.9.

Mar 1, 2017

By Esperidiana A. B. Moura, Elizabeth Carvalho L. Cardoso, Glauson Aparecido F. Machado, René R. Oliveira

Plastics global annual production exceeds 250 million tons and more than 40% of the total plastic production is used as packaging materials. In recent years polymeric materials derived from biomass have received great attention due to scarce petroleum resources and environmental concerns. PLA is one of the most extensively studied bio-based and bio-compostable aliphatic polyesters; nevertheless, high brittleness and low toughness limits its application. Blending PLA with PBAT (Poly(butylene adipate-co-terephthalate)), an aliphatic-aromatic copolyester, was the solution found due to its high toughness and biodegradability. Differences between PLA and PBAT solubility parameter values lead to the formation of immiscible blends as well as reduction in their mechanical performance besides a poor morphology; so, 5% of pre-irradiated PLA and a previous compatibilized PLA/PBAT (EcovioTM) were added to PLA/PBAT blends in order to improve miscibility phases. Investigations were accomplished on phase morphology (SEM), mechanical properties, thermal behavior and X-ray diffractions (XRD).

Mar 1, 2017

By Sheikh Abdul Rezan, M. N. Ahmad Fauzi, Yong Jing Hui, NORLIA BAHARUN, Noor Izah Shoparwe, Srimala Sreekantan

In this paper, the effect of carbon reductant on carbothermal reduction and nitridation of copper-doped titanium oxide (Cu–TiO ) was investigated.

Mar 1, 2017

By Shengping Li, Wei Lv, Gangqiang Fan, Xuewei Lv, Yingyi Zhang

The electrical conductivity of high titania slag, as being an important fundamental physical property utilized in the theoretical understanding of mass transfer phenomena and requirement of practical electric smelting processes, were measured by AC Impedance Spectroscopy using four-electrode method for ternary TiO2–FeO–Ti2O3 slag system based on 85 type of titania slag in Panzhihua in this work. The experiment results show that the slags have a high magnitude of the order of 80–180 s/cm−1 in the whole experimental temperature range from 1523 to 2013 K. The Ti2O3 exhibits very strong effect on increasing the electrical conductivity of high-titania slag since the specific values averagely increase by 55 s/cm−1 with corresponding Ti2O3 content range from 10 to 16 wt%. the X-ray diffraction gram and phases calculated by FactSage are presented and interpreted to discuss the impact of phase change on the electrical conductivity.

Mar 1, 2017

By Isauro Rivera Landero, Martín Reyes Pérez, Eduardo Cerecedo Sáenz, Javier Flores Badillo, Mauricio Guerrero Rodríguez, Juan Hernández Ávila, Eleazar Salinas Rodríguez, María Isabel Reyes Valderrama

During column flotation of mining tailings of the Dos Carlos dam, it was observed that the effect of surface liquid flow (JL) is a variable that determines the rate of rise of packing bubbles and therefore, causes the generation of gas retained within the columnar system. Also overall more stable laminar flows were observed, in a range of superficial flow of liquid in the bottoms stream (JLT) from 0.446 to 0.68 cm/s, showing the stability in the range of superficial gas flow (Jg) from 0.1 to 0.5 cm/s. Observing a uniform bubble size for the three JLT evaluated, with a diameter between 0.05475 and 0.2525 cm, at all the range evaluated of Jg. Furthermore, an uniform performance was obtained, and with the same rate of rise of packing bubbles, showing a greater packing bubbles at JLT = 0.446 cm/s, due to the lesser bubble size observed, in comparison with the values of JLT of 0.68 and 1.017 cm/s.

Mar 1, 2017

By Greg Andrews, David Dreisinger

The Foxtrot deposit of Search Minerals contains a range of rare earth element containing minerals including allanite, fergusonite and bastnasite. The Search Minerals Direct Extraction Process for treating these minerals involves coarse crushing of the ore to -6 mesh (3.45 mm), acid treatment at 200 °C in a novel reactor configuration, water leaching, various purification steps to reject iron, aluminum and uranium/thorium (present in small amounts) and finally precipitation of rare earths as an oxalate and calcination to form a mixed rare earth oxide product for refining. The economics of the process are presented.

Mar 1, 2017

By Qingjun Zheng, Robert Vasinko

Cladding by plasma transferred arc (PTA) welding is widely used for enhancing the surface properties of a metallic component, in particular wear, high temperature and corrosion resistances. This paper presents the application of Kennametal Stellite PTA cladding technology, especially the DuraStell PTA process technique, for tungsten carbide composite cladding for boiler tube application. DuraStell PTA process gives low heat input to the substrate and fast deposition rate. The cladded boiler tube samples showed more uniform carbide dispersion in the cladding, less base metal dilution, and insignificant effect on the microstructure and mechanical properties of the substrate base metal, in comparison of the traditional PTA and other arc welding process.

Mar 1, 2017

By Hongxu Li, Zhaobo Liu, Zihan Zhao

A completely new process of selectively recovering Sc3+ without impurity of Fe3+ from Bayer red mud was developed. Prior to water leaching process, red mud needs to be digested and sulfated at a low temperature and subsequently roasted at a higher temperature for a period of time. During the roasting process, the products such as SO2, SO3 and H2SO4 molecules of thermal decomposition of sulfites including NaFe(SO4)2 and NaAl(SO4)2 could be recycled and reused as the raw materials of sulphuric acid. The leaching results indicate that roasting temperature and roasting time are the main constraint on selective leaching performance of scandium. As the sulfated red mud sample is roasted at 750 degrees C for 40 min and subjected to water leaching at 50 degrees C for 30 min, 53.0 wt% Sc3+, <1.0 wt% Fe3+, <0.3 wt% Si4+ and ~8.9 wt% Al3+ could be leaching out. Of note, the solid-liquid separation process is quite easy to be carried out.

Mar 1, 2017

By Bin Xu, Qian Li, Xiaoliang Liu, Yongbin Yang, Hongwei Li, Tao Jiang, Yan Zhang

The direct cyanide leaching rate of gold from a gold calcine was only 71.33%, due to 19.51% of gold being encapsulated in the iron oxides. To enhance the cyanide leaching of gold, the calcine was pretreated with acid or alkali washing. The mechanisms by which acid and alkali pretreatment improve gold leaching from calcine are investigated through chemical analysis, XRD, and SEM-EDS characterization.

Mar 1, 2017

By T. Thuy Minh Nguyen, Sathish K. Lageshetty, Paul Bernazzani

The addition of nanoparticles to epoxy resins often results in changes in the physical properties of the material particularly when dealing with thin coatings. By characterizing the mechanism of interactions between nanoparticles and polymer chains the material could be tailored for specific applications or properties such as enhanced biodegradability. This study compared the characteristics of common DGEBA resin coated on a silicon substrate and embedded with nanoparticles of TiO2 and Fe2O3. Specifically, we investigated the rate of curing, and the thermal stability of these nanocomposites. Results show changes in the stability for compounds containing TiO2, while Fe2O3 significantly enhanced the curing rates of the nanocomposites while maintaining similar physical properties.

Mar 1, 2017

By Zhiqiang Zhou, Libin Zhu, Zizong Zhu, Hao Xiong, Yuchuan Ding

In order to utilize the lean ore resources from XinJiang rationally and optimize mixture, laborarory measurements have been carried out under different basicity, various mixed carbon content as well as the properties (ratio) of fuel particle size by the sintering pot for further microstructure analyses. The results show that sinter strength falls by 5.0%, low temperature reduction disintegration index (RDI) drops off to the lowest in certain ranges. The natural degradation index of sinter is much higher when sinter basicity is between 1.65 and 1.75. The sinter strength increases when sinter basicity is between 1.75 and 2.0. Meanwhile, the sinter strength and RDI +3.15 improve with increasing carbon content. And the sinter strength and RDI+3.15 both decrease with the decrease of the distribution ratio of small fuel particle, thereby decreases the yield of sinter. Microstructural analyses have been investigated to figure out the mechanism of the influence of the three factors on sinter.

Mar 1, 2017

By Toshiyuki Nohira, Eiichi Takeuchi, Tetsuo Oishi, Hideki Ono, Hirokazu Konishi

Liquid metals were investigated as alloy diaphragms in molten salt electrolysis. Liquid metals have higher diffusion rates of elements than those of solid metals during electrolysis. Sn electrodes were used for the first step to study the electrochemical formation of Dy and Nd alloys in LiCl-KCl eutectic melts, demonstrating selective recovery of rare earth metals into liquid tin electrodes.

Mar 1, 2017

By Marcos V. F. Fonseca, Djalma Souza, Luiz G. X. Borges, Sergio Monteiro, Caroline G. de Oliveira, Ygor M. de Moraes, Janine F. de Deus, Frederico M. Margem

Recently, the natural fibers have been studied as alternative reinforcement material to the use of synthetic fibers. Aiming to improve the properties of natural fibers composites, it is investigated the use of natural fibers fabrics, since they provide multidirectional reinforcement and enables the introduction of a larger fiber volume fraction. In this work, it was investigated the tensile behavior of the epoxy matrix composites reinforced with different volumefractions offabric made of Ramie, a highly resistant lignocellulosic fiber. The specimens were made by pressing the fabric with liquid resin to guarantee total impregnation, and then cutting the fabric in the mold format. Finally ,the fabric layers were placed into the mold with the liquid resin and catalyst. They were cured for 24 h and tested. The results revealed an increase in the tensile strength and almost no effect in the elastic modulus with the increase of fabric volume fraction.

Mar 1, 2017

By Bin Xu, Qian Li, Xiaoliang Liu, Yongbin Yang, Tao Jiang, Yan Zhang

The cohering behavior of iron ore pellet powder in kiln cannot be reflected entirely through the conventional briquetting method, so a novel natural stacking method was proposed in this paper. The results showed that in the two methods the cohering strength of powders from different iron ore pellets (numbered A, B and C) rose with the increase of roasting time and temperature andpresented the same result, i.e., C > B > A. Comparatively, the natural stacking powders obtained much lower cohering strengths under the same roasting condition. The structure analyses of ring from the kiln tail and cohering briquette by the natural stacking method indicated that the occurrence of crystallized particles of them were extremely similar. Therefore, the initial information of pellet powder’s cohering behavior could be provided by the natural stacking method, improving the methods to study the actual ringing process and mechanism of pellet powders in kiln.

Mar 1, 2017

By Johne Jesus Mol Peixoto, Ciro Azevedo Silva, Itavahn Alves da Silva, Weslei Viana Gabriel, Leticia Queiroz Ribeiro, Carlos Antonio da Silva, Varadarajan Seshadri

In this study,the influence of the immersion depth, casting speed on the flow characteristics in a beam blank mold with two tubular nozzles have been investigated using a physical model as well as CFD simulations.The results of CFD simulations were found to be consistent with the results of experiments in the physical model.The liquid jet spreads faster the flange region compared to the web region. This can lead to a non-uniform shell thickness along the cross section resulting in uneven solidification of the skin. The jet penetration depth ranged between 66 and 77 cm. The average intensity of meniscus fluctuation was 0.22 mm, and the maximum fluctuation was found to be 0.85 mm. Based on these results, the suggested optimum operating parameters for immersion depth and casting speed were 75 mm and maximum casting speed of 1 m/min.

Mar 1, 2017