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By David Cocke

Study of surface and subsurface interfacial chemistry of metallic and similar systems has its enormous technological importance. Copper, for example, is a common component of many alloys and bulk amorphous systems. It is being increasingly studied today because of its use for electronic interconnect systems where processing is done below 200 ºC. Since several types of copper oxides exist, and the degree of their formation is dependent on temperature, perhaps characterization by EDS-SEM depth profiling and EIS might delineate one type of oxide from another. In this paper, we described our work on transformation of copper oxides with temperature ranging from 70 to 350 °C and their characterization by SEM, EDS, and XRD. We also showed the use of the phase angle portion of the impedance as a means to identify the predominant structure and the transition through Cu3O2 between the predominant stable CuO and Cu2O.

Jan 1, 2009

By Kunihiko Takahashi, Gjergj Dodbiba, Hisayoshi Umeda, Toyohisa Fujita

"An increasing number of mobile phones is increasing the number of the discarded mobile phones. Many efforts are thus being made to collect and recycle these devices. This paper is a short introduction of the recycling system of precious metals from the discarded mobile phone, currently available in Japan. Moreover, an attempt has been made to compare the energy recovery and the mechanical recycling of plastic wastes from the discarded mobile phone. The assessment has been carried out in the context of the life cycle assessment methodology (LCA). The environmental impact of each option was assessed by calculating the following impact indicators: depletion of abiotic resources (ADP), and global warming potential (GWP). 1. Introduction In 2003, the demand for mobile phones was increased since the camera was included in a mobile phone and the 3rd generation of mobile phones was introduced. In turn, the number of discarded mobile phone is rising sharply. Generally speaking, all the metallic parts of mobile phones can be recovered and recycled by using smelting and purification techniques. The recycled materials are then used to fabricate other new products."

Jan 1, 2008

By Sergio Neves Monteiro

The efficiency by which an applied load is transmitted through the composite structure depends on the strength of the interface between the matrix and the second phase. In fiber reinforced composites, the interfacial shear stress plays a major role in the composite capacity to support the applied load. This interfacial stress can be obtained by means of pullout tests using the fiber embedded to a certain length in a socket of the matrix material. In the present work, pullout tests were performed to evaluate the interfacial shear stress of ramie, a relatively strong natural fiber, reinforcing polyester matrix composites. The general result permitted to calculate a critical length for the ramie fiber embedded in polyester resin. From this critical length, the value of the interfacial shear stress was calculated. An interpretation of this result together with SEM observation displayed a relatively weak bond between the ramie fiber and the polyester matrix.

Jan 1, 2010

By Jilai Xue

Fe-Ni alloys can be used as raw material in making stainless steel. Laterite nickel ore is one of mineral resources for producing nickel alloys. In this work, the laterite ore after dehydration at 800 °C and the anthracite as reducing agent were mixed for pre-reduction at 900 °C, and then reduced to form Fe-Ni alloys at 1550-1620 °C through carbon-thermal reduction process. A high Ni-content alloy component in the metallurgical mixture can be formed through pre-reduction. Better separation of the resulting metals from the slag is found with lower Ni-content alloys produced or higher temperatures during reduction. An effective processing of Fe-Ni alloys needs further understanding of the process fundamentals and optimizing of the process parameters.

Jan 1, 2010

By Chao Li, Qian Li, Yong-bin Yang, Kai Li, Qiang Xie, Yuan-yuan Zhu, Dong-ye Li, Qi-bing Tan

"The permeability of sintering mix is a vital technological property in sintering process. However, it can only be measured by off-line method on samples picked from the production. In order to acquire the properties of sintering mix accurately, on-line measuring of permeability is urgently required. Based on the reflection characteristics of bed permeability on pipe flowing parameters, a new method is presented in this paper for on-line measuring of sintering mix permeability. The measurement can be performed by blowing gas flow in the bed with the measuring pipe. Measuring results are obtained by picking the data on flowing rate and pressure in the pipe. The function of flowing rate to pressure may be certain for samples with the same permeability. Thus, the permeability was determined by contrasting this function to the result of off-line measuring, and the relative coefficient or R2 value was more than 99%.IntroductionThe permeability of sintering mix is a vital technological property in sintering process, which directly determines production and quality of sinter, or even determines whether the sinter production is carried out smoothly [1,3].The permeability have more obvious influence on vertical sintering speed, which is mainly related to air quantity passing through material bed. Under certain inducing capacity and negative pressure, the vertical sintering speed mainly depends on the permeability of sintering mix. Low permeability may make burning through point of sintering move back, and the sinter mix cannot be burnt through. High permeability may make burning through point of sintering move forward, improving production efficiency by increasing the speed of sintering machine [4] Good permeability means a small resistance of fan ,reduction of negative pressure of sintering machine, and full contact between air and sulfide, which can strengthen physical-chemical reaction during sintering process and increase desulphurization rate. In gas well through material layer process, gas-solid desulfurization reaction and gas-solid-liquid heat exchange are completed and hot gas through the combustion zone supplies the sintering process with heat. Finally uniform sintering of the material layer in height and width direction is achieved [5] While high permeability index leads to weak sinter strength, fast sintering speed, short residence time of high temperature region and little liquid phase. Moreover, liquid phase in the fast cooling process is too late to fully crystallize but forming glass phase which is harmful to sinter strength as well. Bad permeability means a big fan resistance and increase of negative pressure of sintering machine, which make the air pass through material layer difficultly. When air and mix contact difficultly, removal of sulfide reduces so that desulfurization is incomplete. Meanwhile, low caking efficiency, slow sintering speed and easily burnt sinter , reduce sinter output. Therefore appropriate permeability of sintering mix is the premise of stable burning through point and satisfactory sinter output and quality."

Jan 1, 2013

By G. Kugler, M. Tercelj

"The use of the up-to date light alloys and their development are in the sharp ascent especially in transportation industry. In the last years the use of the magnesium alloys for the various purposes was strongly increased. The aim of present research was to study the influence of solidification rate on hot workability and on obtained mechanical properties of AM60 magnesium alloy. The study was also focused on possibility to omit prior homogenisation process which would result in cost reduction. The solidification of gravity cast alloy has been investigated with various methods of the thermal analysis: in situ simple thermal analysis and simultaneous thermal analysis. In order to reveal optimal hot working conditions the deformation behaviour was studied in the temperature range 200-450°C and strain rates between 0.001-lOs-1. Mechanical properties have been studied with tensile and impact toughness testing.IntroductionIn recent years, the increased demand for magnesium alloys has been mainly driven by the need of automotive and transportation industry to reduce the weight, as this is the most important parameter to reduce the energy consumption. Beside their very low weight in comparison to other metals, the magnesium alloys are characterized by good machinability, corrosion resistance and good mechanical properties, and can thus compete with aluminium alloys and for some applications even with steels. Due their decreased workabilty they are typically used as cast alloys, but in recent years also the research of their wrought state has become more extensive [1-7]. Decreased hot workability of magnesium alloys originates from their hexagonal close-packed structure. One of the most popular magnesium alloys with great potential for many applications is AM60 (MgA16Mn), which is predominately used for casting. But its application could be increased if the mechanical properties, could be improved. This can be done by hot working. Namely it is well known that wrought microstructure is characterized by better mechanical properties in comparison to as-cast state. On the other hand due to its low hot workability the homogenization process is required prior hot deformation, which results in increased production costs. Thus the aim of the present research was to study the influence of solidification rate on hot workability of AM60 alloy in order to improve its mechanical properties and to check the possibility of producing near-net-shape casting products omitting homogenisation process by employing small additional deformations after casting. Within the framework of this research the solidification of gravity cast AM60 alloy has been investigated with various methods of the thermal analysis."

Jan 1, 2011

By Husamuddin Ahmadzai

A survey of regulations and state of the art control technologies is presented relating to the smelting of primary aluminium, copper and recycling of residues. Some costs associated with the alternatives and trends for the coming decade in this. sector are identified.

Jan 1, 1992

By S. Y. Tan

The thermal stability of fully silicided NiSi with arsenic doping on silicon was investigated. The aims of the work were to investigate the Ni silicide phase-related issues associated with arsenic dopant and thermal annealing on Ni-FUSI/HfO2/Si and Ni-FUSI/HfSiO/Si gate stacks. It was found that arsenic-incorporation demonstrated some improvement in both morphology and phase stability of nickel silicided films at high processing temperatures regardless underlying gate dielectrics. The correlations of Ni-Si phase transformation and arsenic doapnt with their electrical and physical changes were established by sheet resistance measurements, X-ray diffraction (XRD), atomic force microscopy (AFM), and X-ray photoelectron spectroscopy (XPS) analysis. Furthermore, the modulation of the work function (WF) of Ni fully silicided gates by arsenic impurity is presented, comparing the effects of dopant (As) on the WF and silicide phases (NiSi and NiSi2). It confirmed that the work function of NiSi can be tuned by implanting arsenic dopant, but it ineffective for NiSi2 phase.

Jan 1, 2010

By Tammy G. R. Portela

A comparative characterization of the dimensional and mechanical properties as well as structural aspects of two different types of fibers extracted from the leaves and petioles of the buriti palm tree was performed. A statistical analysis revealed that both types of fibers present a significant dispersion in length and equivalent diameter. However, the corresponding intervals of dimensional variation are sensibly different. The tensile properties showed that both types of fibers display a tendency of higher strength for smaller diameters. Moreover, the fibers extracted from the leaves depict a comparatively lower strength. By contrast, the fibers from the petiole present an average strength sufficiently high for the use as reinforcement of polymeric composites. The structural aspects of tensile-rupture fibers, characterized by scanning electron microscopy, showed marked distinction in the microstructure and fiber behavior of both types of investigated fibers. This could explain the differences in mechanical behavior

Jan 1, 2010

By J. C. Pandey

The paper highlights the experimental investigations to characterize texture and plastic strain ratio r-Bar in auto grade steel sheets by ultrasonic measurements, whereas attempts were made to characterize interlamellar spacings in pearlite, tensile stresses and torsional properties in prestressed concrete wires by eddy current measurements. Good correlations were obtained between the testing parameters (such as ultrasonic attenuation and velocity in case of steel sheets as well as eddy current out put voltage and phase angle in case of steel wires) and the materials properties (such as texture, plastic strain ratio r-Bar, interlamellar spacings in pearlite, tensile stresses and torsional properties). 15 MHz normal direct contact and 20 MHz delay line normal shear wave probes were used for ultrasonic measurements. Eddy current measurements were done using an absolute coil probe with variable frequency selection. The experimental results show the possibility of nondestructive on line measurement of the above microstructures and properties.

Jan 1, 2010

By Qingsheng Liu

A new method of recycling aluminum dross for preparation Al-Si-Ti alloy was studied in this paper. This was carried out in two processes. first the aluminum doss was pretreated by leaching and calcining process, the fine purity and phase of the intermediate oxide powder up to electrolysis demands, then, could be obtained when aluminum dross after washing have been leached for 2h at 100? in 20% hydrochloric acid and calcined for 2h at 1200?, which was treated by cryoite-based molten salt electrolysis. Finally, the Al-Si-Ti alloy was successfully obtained through electrochemical co-deposition in the cathode shows a typical as-cast microstructure. This new recycling method can produce high quality alloy and may bring remarkable economic and social benefits.

Jan 1, 2010

By Vincent Menard

The purpose of the present work is to demonstrate the removal of manganese from a neutral leach zinc-rich solution ([Zn] =150 g/L) at 80°C by oxidative precipitation using a gas mixture of sulphur dioxide (SO2) and oxygen (O2). In order to determine the optimum conditions for manganese removal, several bench-scale semi-batch experiments were performed, where the effects of ORP and gas mixing were investigated. These tests showed that SO2/O2 is a fast and effective oxidant for removing manganese down to ppm level as long as the appropriate ORP is attained/maintained and gas transfer kinetics are optimized.

Jan 1, 2006

By Ram Avtar

High tensile thick plates (>80mm, weight ~3000 Kg) of medium carbon low alloy steel, when heat treated, manifested higher percentage of crystalline area (>20%) in fractured surface. Such problem was not encountered in thinner plates. The genesis of higher crystallinity in fracture was examined. It was observed that the thicker plate undergone slower rate (Average 0.9oC/Sec.) from soaking temperature to Ms temperature) of cooling after austenising during oil quenching and thereby quenched microstructure had upper bainites. During tempering of as quenched bainite, additional precipitation took place at the lath boundaries of bainite. This led to weakening of grain boundaries and aided easy crack propagation during fracture and resulted in formation of higher percentage of crystalline area in fractured surface. Enhancement in cooling rate (Average 1.8oC/Sec. from soaking temperature to Ms temperature) of austenised plate by switching over from oil quenching to water quenching practice resulted in complete transformation of austenite into martensite and produced ductile fracture (zero Crystallinity). Plates conformed improvement in mechanical properties between 2-5%.

Jan 1, 2009

By Slobodan Radosavljevic

The polymetallic W-Pb-Bi-Ag ore from the ?Nova jama? ore zone of the Rudnik ore field have been investigated. Contact-pneumatolytic (skarn), pneumatolytic-hydrothermal, and hydrothermal mineralization phases are defined in this ore zone. The most significant mineralization phase that gave compact ore bodies is pneumatolytic-hydrothermal phase. A relatively pure Mo-free scheelite is the only tungsten-bearing mineral. Lead minerals are mostly presented by Pb-Bi sulphosalts and much less with galena. The image analysis coupled with Energy Dispersive Spectrometry (EDS) analysis on a Scanning Electron Microscope (SEM) was applied to the characterization of a W-Pb-Bi-Ag ore as an efficient tool for mineral quantification. Results of EDS (Energy Dispersive Spectrometry) analyses gave the empirical formulae: Pb1.91Ag0.05Cu0.08Bi1.93S5 for cosalite, Pb0.98Ag0.03Cu0.05Bi1.99S4 for galenobismutite and galena Pb0.99Ag0.03S.

Jan 1, 2006

By F. Kongoli

Viscosity is an important parameter of copper smelting and converting processes. It affects the settling of matte or metal droplets in the slag, distribution of elements etc. Despite this importance, confusion exists on the viscosity of copper smelting slags as a result of disagreements found among the measured viscosity data of several authors especially in the slags of high ferric iron content and close to magnetite precipitation. In this work a critical review of the existing data on the viscosity of copper smelting slags has been first carried out and the effect of oxygen potential on the viscosity of copper smelting slags has been clarified through a coupled quantification of viscosity and liquidus temperature. The confusion in the literature has been clarified and the importance of the relation between the viscosity and the liquidus temperature is discussed.

Jan 1, 2003

By Xuan Li

Aluminum slag is generated when aluminum metals are recycled through a smelting process in the presence of salt. There are small amounts of aluminum metals trapped in the aluminum slag. This research aims at evaluating the use of aluminum slag as an expansion agent for the production of lightweight concrete by taking advantage of the residual aluminum metals in the slag. The research identified key elements of producing lightweight concrete products through utilizing various mixture components including sodium hydroxide (NaOH), lime (CaO), cement, and gypsum. The volumetric expansion rate was investigated and the density and strength of the products were determined. The results show that aluminum slag can be utilized for the production of lightweight concrete products.

Jan 1, 2010

By Elisa Alonso

Recycling is generally a more sustainable alternative to landfilling. Its financial costs however, do not always justify its practice, especially in the short term. As a result, even for precious metals such as platinum, significant amounts can end up unrecovered. In considering risks of materials scarcity for firms that require platinum and platinum products, this paper examines how recycling provides additional benefits as a risk-mitigating strategy against scarcity. The experimental platform for this examination is a System Dynamics simulation model that strives to capture the dynamics of platinum market supply, demand and price. The detailed structures of supply and demand are key features of the model. Results show that since the secondary supply of platinum depends on a supply chain separate from primary extraction, recycling can diversify the risks of primary supply instabilities and reduce the impact of price fluctuations upon firms.

Jan 1, 2009

By B. B. Agrawal

Iron ore fines is an area of concern in India. A possible avenue is to use these fines for sponge ironmaking. Work has been carried out to pelletize these fines with coal and a suitable binder, and cure them in ambient atmosphere to retain in-situ reductant. Pellets were characterized for physical strength and metallisation. Critical factors were granulometry was percentage of coal & binder. In laboratory tests, pellets got metallized faster compared to lump ore. Large-scale trials were conducted in a 12-meter long rotary kiln plant. For 90% metallization, required residence time was only 60 minutes against 240 minutes for lump ore. Coal requirement also decreased. Investigations established the fast reduction nature of pellets. This is due to reduction-reactions occurring simultaneously at many sited within the composite pellets, in addition to the diffusion of reducing gases from the surface of the pellets to its core. The developed process is a value addition in the conventional pelletmaking and is environment-friendly also.

Jan 1, 2006

By Jose R. Parga

In mining operations, cyanidation is the ,predominant method by which gold and silver are recovered from their ores and it is recognized that cyanide consumption can be a major factor that contributes to the operating costs for such operations. Also after extraction and recovery of precious metals a certain amount of cyanide is delivered to the tailings pond and must be considered with respect is environmental problems due to the toxicity of cyanides. In this regard, the Air-Sparged Hydrocyclone (ASH) has been used as a reactor for the treatment of cyanide solutions in two ways; first for cyanide recovery by acidulation using the Mexican modification of the Mills-Crowe process and second for cyanide destruction by oxidation with the use of chlorine dioxide (ClO2). In both cases, excellent performance can be achieved using the high capacity ASH system.

Jan 1, 1998

By E. Fregeau-Wu

The mineralogy and grain size distribution of phases in a steelmaking slag and experimental products from the heating of the slag under various conditions were determined to explore the possibility of recycling of the iron and manganese to the blast furnace. The steelmaking slags consisted of three major phases: dicalcium silicate, dicalcium ferrite, and Mg-Mn-wustite. Most of the phosphorus was contained in the dicalcium silicate and to lesser extent in the dicalcium ferrite. Due to the fine grain size of the dicalcium silicate, grinding and magnetic separation required pretreatment to increase the grain size and hence the liberation. Experiments on a steelmaking slag were conducted by heating the slag to 1633-1748°K( and slow-cooling in an inert atmosphere at various rates with or without the addition of fluorspar (CaF2) as a flux. Grain size distribution analyses of the starting material and the slow-cooled products were performed using the SEM-IPP area scan method and the QEM*SEM linear scan method. Comparable and reproducible results were obtained on the same sample using both methods. A size versus volume percent plot showed the increased grain growth most effectively. Examples of the grain size distributions obtained were used to show that a higher soaking temperature prior to slow-cooling, a slower cooling rate, and the addition of fluorspar to the slag promoted grain growth.

Jan 1, 1989