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By H. Fukushima, T. Ohgai, N. Baba

The electrodeposition behavior of Zn and the morphology of the deposited Zn were studied in electrowinning solutions containing polymer additives such as gelatin and polyethylene glycol (PEG). The cathode potential was shifted in a less noble direction and the polarization resistance for Zn deposition increased with increasing concentrations and molecular weights of both gelatin and PEG added to the electrolytic solutions. However, when the molecular weights of these additives exceeded about lxlO4, the cathode was depolarized and the polarization resistance for Zn deposition decreased with increasing molecular weight. The crystal grain size and the (002) orientation of the deposited Zn became smaller when the concentration and molecular weight of the additives increased, and the cathode was polarized.

Jan 1, 2000

By Tarek M. Hatem, Salah M. Bedair, Khaled H. Khafagy

Our understanding for intrinsic stresses and defects evolution in photovoltaic devices has became an essential part of new developments. In particular, Multi-Junction Photovoltaic (MJ-PV) modules depend on multi-layer structures that may suffer high dislocation-densities as a result of high lattice and thermal expansion coefficient mismatch. These defects limit the performance, reliability, and lifetime of PV devices. In the current study, a three-dimensional multiple-slip crystal-plasticity model and specialized finite-element formulations are used to investigate InGaN growth on Si substrates. The formulation is based on accounting for thermal and intrinsic stresses as a result of different processing conditions and microstructures. Furthermore, the formulation was used to investigate a recently developed technique, Embedded Void Approach (EVA), which can be used to address both the high density of defects and the cracking/bowing of InGaN growth on Si. The current work lays the groundwork for more extensive use of silicon in MJ-PV devices.

Mar 1, 2018

By Yuya Nakai, Kuniaki Murase, Kazuhiro Fukami, Atsushi Kitada, Ken Adachi

The resources of vanadium –titanium magnetite in China are very abundant, most of which are used to prepare titanium-rich materials. Titanium pigment, electric welding bar and titanium sponge are made from titanium-rich materials such as synthetic rutile and titanium slag etc. To fully utilize titanium resources, many production methods of titanium-rich materials were proposed. In this article, authors review on methods of preparing titanium-rich materials which are Electric Smelting Process, Reduction-rust Process, Selective Chlorination Process, Acid Leaching Process, and sum the advantages and disadvantages of them. Existing problems and possible tendency of production methods of titanium-rich materials are also discussed.

Mar 1, 2018

By P. M. Tait, N. A. Warner

"The refining of thermally produced zinc is currently performed using a highly energy intensive and arguably outmoded process, distilling zinc under atmospheric pressure at temperatures of 900°C to 1000°C. In order to produce refined zinc more profitably and with less environmental impact a new process has been proposed. This process is generic to all thermal zinc smelters and aims to match the purity of zinc from current technology (99.99%-99.999%). The objective is to perform all separation processes using only the heat contained in the smelter product stream. Vacuum conditions are extensively used lowering operating temperatures and enhancing separations. As part of this process zinc is distilled under vacuum from high concentration obtaining a refined product with respect to lead content. A mathematical model has been developed from fundamental principles to describe this stage, the distillation of zinc across a temperature difference between two circulating zinc streams in open channels under vacuum. Heat for the distillation is supplied by the liquid phase, necessitating a large recycle to maintain high operating temperatures, and keep zinc concentrations high. In determining this model and the operating conditions required, relationships between temperature, pressure and composition are considered.IntroductionCurrent technology (the Refluxer) used to refine thermally produced zinc is both expensive and highly inefficient. At present 80% of the worlds zinc is produced via the electrolytic process reflecting the poorer performance of the thermal route, the zinc-lead blast furnace and Refluxer. A new process is proposed to overcome the drawbacks of current processes. These drawbacks are both economic and environmental. The Refluxer requires 6.6 GJ of energy to refine one tonne of SHG zinc 1, other disadvantages of the Refluxer stem from high operating temperature, around 900°C, and liquid zinc being highly corrosive towards ferrous metals. The Refluxer is constructed from silicon carbide sections which join together by means of flat machined faces making liquid metal leaks inevitable. The Refluxer columns are very sensitive to thermal cycling, thermal shock and mechanical vibration, which easily lead to structural failure. To avoid thermal stress on the columns the feed rate and feed temperature need to be kept constant which means the feed baths to the columns must be able to accept solid and liquid feed as the Refluxer has to operate when the smelter is shut down."

Jan 1, 1998

By Mingming Zhang, Marshall S. Coe, Marcelo W. Andrade

To supply iron units and flux burden in blast furnaces, sinter basicity is one of the vital parameters for sinter plants. The sinter basicity also plays an important role in sinter quality since it imparts the formation of different mineral phases in sinter. Pot-grate sintering tests were carried out with low and high basicity to investigate the effects of sinter basicity on sinter mineralogy, properties and productivity. It was found that with an increase in sinter basicity, both sinter productivity and reducibility (RI) increased. Tumbler index (TI) and low temperature degradation index (LTD) of high basicity sinter were comparable to low basicity sinter. Softening and melting tests showed that sinter with 3.5 C/S basicity had slightly higher softening temperature comparing to lower basicity sinter with C/S 2.6, acid and fluxed pellets. XRD analyses confirmed the formation of silico-ferrite of calcium and alumina (SFCA) and calcium ferrite (CF) in the tested sinter samples.

Jan 1, 2015

By Leizhang Gao, Zhengfeng Qu, Pingsheng Lai, Chenguang Bai, Meilong Hu

Since Fray-Farthing-Chen (FFC) Cambridge process was proposed in 2000 for electrochemical extraction of titanium from titanium oxide, a great quantity of research has been carried out to investigate the mechanism of the electro-reduction of the process. Results show that the intermediate products of perovskite phases are inevitable during the electro-deoxidation process. In this paper, a new perspective focus on the anodic behavior was applied. The behavior of the graphite anode with different times has been investigated. Although the main anodic process in the electrolysis is the oxygen evolution by means of the CO2. The interphases of calcium species appeared on the cathode are closely related with chlorine ions in the molten CaCl2. In addition, the released CO2 from the anode is related with the formation of CaCO3 which floated on the surface of the molten salt.

Mar 1, 2018

By Moelans. N.

A method using an ex-situ electrochemical measurement device was developed to determine the oxygen potential of non-ferrous metallurgical slags. The electrochemical cell consists of the molten slag sample, an inert Ir electrode, a stabilized Zr02 solid electrolyte and a NilNiO reference electrode. Different slags from non-ferrous pyrometallurgical processes were analysed at I 100 and 1200 °C and pO2values between 10-3 and 10-12 bar were obtained. The measurements were evaluated with thermodynamic calculations and using processing considerations. It was found that the reproducibility and stability of the measurement was significantly improved by shielding the molten slag from the atmosphere by a thin layer of carbon, especially for slags with a low oxygen potential.

Jan 1, 2003

By Manuel Pérez-Tello

A mathematical model to represent the expansion and fragmentation of copper matte particles oxidized under flash converting conditions is presented. The model assumes the particles to be initially nonporous, have a constant mass prior to fragmentation, and travel at a constant velocity throughout the reaction chamber. The model requires the specification of five parameters: the particle expansion rate, a fragmentation diameter factor, a fragmentation size distribution parameter, and the fractions of the finest and the coarsest particles in the feed that undergo fragmentation. The model predictions show good agreement with experimental data collected in a laboratory flash converting furnace over a wide range of experimental conditions. The evolution of the size distribution of the particles along the reactor length was computed, and the model parameters were correlated with the experimental operating variables. Model predictions indicate that particle residence time is an important factor in the generation of dust. The presence of two maxima in the particle density function may be attributed to turbulent conditions prevailing in the furnace, which cause particles to follow very different trajectories within the furnace even if they are injected at the same location.

Jan 1, 2006

By Adam Gesing, Paul Marchwica, Jerry Sokolowski, Sharon Lackie

"Often referred to as SEM-EDX, energy-dispersive spectroscopic analysis of characteristic fluorescence x-ray is a standard technique for semi-quantitative elemental composition analysis in scanning electron microscopy. It is quick and extremely useful for identification of phases in the sample microstructure, as long as the constituents are significantly larger than the probe volume from which the fluorescence x-rays originate. The probe volume ranges from a few to several microns, depending on the electron beam spot size and the acceleration voltage. We report on a new variant of an EDX technique developed to overcome this limitation and allow quantitative elemental analysis of smaller phase constituents, down to a size of several nanometers. This variant involves the calculation of compositions of individual phases from multiple analyses of areas containing phases of interest. This significantly increases the usefulness of EDX for quantitative analysis of new nano-structured materials.IntroductionIn any elemental micro-analytical method, the sample material is illuminated by a probe beam that excites an interaction volume of a sample to emit a characteristic signal. This signal in turn interacts with the sample material through absorption and fluorescence mechanisms before a portion of it is collected by a suitable detector and analyzed for elemental composition. The spatial resolution of the method depends on the minimum interaction volume between the probe beam and the sample material.Laser light beams can be tightly focused to a spot size limited by the photon wavelength and can be used to sample the surface of any material. In micro-LIBS (laser-induced plasma spectroscopy) a focused laser beam ablates and vaporizes a small volume of material from the sample surface, creating a plasma spark. Spectral analysis of the light emission from the plasma spark allows the semi-quantitative determination of the elemental composition of the material removed from the sample surface. The smallest reproducible craters achieved are ~ 3mm in diameter and a few nanometers in depth. [l]Particle probe beams of ions or electrons can be focused to a diameter of a few nanometers at the point of impact on the sample. Ions sputter the sample atoms from the point of impact, and the sputtered ionized material is analyzed by mass spectroscopy in a secondary ion mass spectrometer (SIMS). [2] This gives SIMS resolution in a nanometer range. SIMS equipment, however, is expensive and not readily available."

Jan 1, 2013

By K. Hussin

Perlis is one of the major producers of ?Batu Reput? in Malaysia and majority of the deposits contain of high-purity calcium and magnesium carbonate. The composition of Batu Reput is similar with the ordinary dolomite. Currently, the ?Batu Reput? is used as filler in the road construction, however with this new invention, it can be value added and maximized its application in the daily life, for example as construction materials, decorative products, souvenir and etc. This paper presents the fabrication of Artificial Marble from ?Batu Reput? and in this case, it was used as filler in the matrix of epoxy which is acted as a binder.

Jan 1, 2006

By Florian Kongoli

While calcium ferrite slags have been successfully used in continuous copper converting for the last 30 years, ferrous calcium silicate slag was proposed about 8 years ago as an additional alternative for copper smelting. Although both slags are normal extensions of each other their phase relations have not been completely clarified. In this paper the liquidus relations of both slags have been quantified at various areas that cover both of them. The existing experimental data have been first reviewed and discussed in relation to the solidification procedure. An original physical model is then used to predict various diagrams of the liquidus surface of both slags. It is shown that the ternary liquidus diagrams normally used for FeOx-SiO2-CaO system are not suitable for industrial slags. The new model diagrams of Fe/CaO versus SiO2 and Fe/SiO2 versus CaO as well as Fe/CaO versus Temperature and Fe/SiO2 versus temperature are proven to be much more convenient for ferrite and ferrous calcium silicate slags. Based on these diagrams the effect of SiO2 and CaO on the melting temperature is quantified. The effect of Cu2O is also quantified through the model. Some Fe/CaO versus Cu2O and Fe/SiO2versus CaO at various copper contents are predicted and the results show good agreement with the experimental data. It is also shown that in the presence of liquid copper, Cu2O is dissolved in the slag depending on the oxidation degree of the system and might lower the liquidus temperature. Some discussions are also presented taking into account plant observations and important conclusions are drawn for copper smelting and converting

Jan 1, 2006

By G. Brooks, J. Naser, M. A. Sattar

CFD models have been developed and numerical simulations have been carried out to predict the formation of foam in oxygen steelmaking. Foam was considered as a separate phase comprising a mixture of gas and liquid. Bubble break up and coalescence models have also been incorporated in a CFD model to predict the number density of individual bubble classes. A population balance equation was used to track the number density of each bubble class. Decarburization with heat generation from chemical reactions was integrated in the process. User subroutines were written in FORTRAN to incorporate the foam formation, the bubble break up and coalescence rate and decarburisation in the main program. The model predicted the foam height, bubble number density, velocity of phases, decarburization, and turbulence. The result from the model has been compared with available data from literature and found to be in reasonable agreement with the experimental and plant data.

Jan 1, 2014

By Kampe. S. L., Baker. Andrew H., Tony Zahrah

"Experimental heats of reaction for the formation of several Al3Ti + TiB2 intermetallic composite formulations have been determined utilizing bomb calorimetry. To overcome the kinetic constraints and achieve ignition in these formulations, a boron (B)/potassium nitrate (KNO3) initiation aid was incorporated within the blended reactant compact. The heat contribution from the initiation aid was regressed to provide estimates of the heat of reaction of the nominal formulations. Powder x-ray diffraction was utilized to identify the products of the reaction and discern any differences between the predicted equilibrium products of the formulation and the actual products.IntroductionReaction synthesis is a technique for the creation of ceramics, intermetallics, and in-situ composite materials [1]. Reaction synthesis is defined by its self, propagating mechanism, where the energy liberated from a localized reaction within a green powder compact is enough to carry the bulk reaction to completion. Achieving a self, propagating state can be achieved in variations of two primary methods of initiation: uniform volumetric heating and directional propagation [2].Uniform volumetric heating involves subjecting a green compact of the unreacted formulation to uniform heating in a furnace to encourage diffusion to initiate the reaction (Figure 1a) throughout the bulk material. Directional propagation utilizes a point heat source at one section of a green compact of unreacted formulation (Figure 1b). The localized exothermic reaction at one point in the compact then initiates the reaction in the section of the compact adjacent to it and fully propagates throughout the entire compact until completion. Initiation of the localized reaction is generally associated with the melting of the constituent with the lowest melting point, with instantaneous initiation of the reaction usually occurring close to that melting point [1]. This melting point can be high in some systems of interest, such as the titanium (Ti) and boron (B) system in equation 1:"

Jan 1, 2011

By Ma Ying

The continuous directional solidification technique of five kinds of special ZA alloys with eutectic, peritectic and eutectoid transfonnation under the condition of continuous casting by heated mold was studied. The mechanism of surface defects appearing in ZA alloy line was discussed and the structure of some defects were analyzed by SEM. The results show that only when the fitting of various technique factors, pressure head, outlet temperature, pulling speed and cooling condition are reasonable under a certain range, can the ZA alloy smooth line be continuously pulled out. Unreasonable techniques will result in hot tear, rough surface, mush outlet, leaking and other defects. The shape and location of solid-liquid zone have an important influence on the formation of the above defects. When the solid-liquid zone is located in the mould outlet or inner mould, the surface of solidification will protrude into the inner mould. If the remaining liquid cannot counteract the solidification contraction, a rough surface will appear. If the solidification surface further into the mould, the ingot in the mould will have a great friction force when pulling and will form a hot tear. When the solid-liquid zone is moved out of mould, the solidification surface will turn into a plane, which easily results in leaking. A vibration or unstable operation will cause an ingot winding during pulling.

Jan 1, 2003

By Shengli Wu, Mingyin Kou, Laixin Wang, Xinliang Liu, Zhennan Qi, Yujue Wang

Softening and melting experiments were conducted on four kinds of imported lump ores named A-D, under different temperature intervals within the self-developed visualization high temperature furnace. By calculating the reduction and shrinking degree under different intervals, softening and melting indexes were determined. These ores all expanded firstly followed by shrinkage with the temperature increasing. The difference of lump ore’s own characteristic led to different softening and melting behavior. The results showed that the looser the structure was, the better the reducibility will be. The compact structure and good reducibility led to high expansion rate. The beginning softening temperature declined and the ending softening temperature increased because of high porosity, which resulted in wide softening temperature interval. The charging ratio of lump ore A should be improved. Lump ore B should be distributed in the center of the blast furnace. Lump ores C and D should be used less.

Jan 1, 2016

By K. Morsi

Titanium-titanium boride whisker (TiBw) composites are emerging as strong candidate materials for advanced applications within the automotive, aerospace and defense industries. Although increasing TiBw volume fraction improves the specific stiffness and wear resistance of titanium, it is usually on the expense of fracture toughness and ductility especially at increased volume fractions of reinforcements where whiskers interlock. This research addresses strategies for microstructural design that may overcome these shortcomings, by generating titanium composites that are locally reinforced with TiBw through in-situ reaction in segregated regions of the microstructure and separated by ductile Ti matrix. The effect of varying composite reinforcement particle sizes (i.e. size of the reinforced regions) on the pressure-less sintering of these dual matrix composites is discussed. Electric current activation was also used to generate high density dual matrix composites and a new simultaneous imaging and modulus mapping technique was used to characterize these unique microstructures.

Jan 1, 2008

By Dominik Hofer

A broad spectrum of tantalum containing input materials can be processed for the production of synthetic tantalum concentrate (“SynCon”). The use of these low grade substances offers a secure alternative to mining of coltan in Central Africa. SynCon is produced in a multi-stage pyrometallurgical process, wherefore the melting behaviour of slags presents an important factor especially regarding the energy consumption and its optimisation. The characteristics of a slag comprising mostly Al2O3, CaO, SiO2 and MgO are influenced by the amount of other oxidic constituents which enfolds the main focus of this study. A hot stage microscope serves for the investigation of the slag behaviour in a temperature range from 1000 to 1600 °C under reducing atmosphere (CO/CO2 gas). The experimental results are compared with thermodynamic calculations (FactSage) to get a better understanding of the process.

By Huang Chao

The thermodynamics analysis on reducing-matting smelting of sulfide ore of lead, antimony and bismuth which use ferric oxide as sulfur fixed agent is first analyzed. Due to the analysis of reaction mechanism, ferric oxide is first reduced to ferrous oxide, then ferrous oxide produce reducing-matting reaction with sulfide ore and reducing agent as reaction equation: MeS+FeO+CO=Me+FeS+CO2. The reaction thermodynamic calculation shows that the reducing-matting reactions of lead sulfide, antimony sulfide, Jamesonite, and bismuth sulfide are feasible, but is infeasible for zinc sulfide. These conclusion provide a feasible method for solve the pollution which produced in the smelting of sulfide ore of lead, antimony and bismuth.

Jan 1, 2006

By Lennart Hedlund

There is today a long and well-documented experience of the use of Boliden "Kaldo' technology for treatment of various feed matedals. The process is In commercial' operation in the Boliden Mineral's Rönnskär plant In Sweden for treatment of copper scraps and lead concentrates (In campaigns). This plant was built In 1976 for treatment of lead dusts from the copper plant but later modified to take other raw materials. Boliden's Kaldo techr:lology Is also In operation since 1991 for treatment of low-grade copper scraps In Enlrlsorse's plant In Porto Marghera (Venice), Italy. The plant is producing 25 000 tons of blister copper ,per year. The Kaldo furnace Isa high :Intensity smelting unit, where several successive treatment steps can be done In the same vessel. The furnace can be totally enclosed to protect the working environment, and the small off-gas volume can easily be dedusted. Input materials can vary over a very wide range, the products will be a dump slag with low (0,5%) copper and lead contents and black copper or blister copper. The dust from the process can be used for zinc production. A new development is autogenous smelting of scrap in a Pierce-Smith converter, implemented at Compagnie Générale d' Èlectrolyse du Palais in France.

Jan 1, 1995

By Volovik A. V. Ivtan, Shelkov E. M. Ivtah

"One of the most power consumption Industrial process is production of Al from bauxites (about 45000KWt.hour electrical energy for production of 1 ton. of technical Al). This process is based at the low efficiency and productivity electrolysis technology.Last years IVTAN investigations give to .us information about possibility to use of high temperature shaft- furnaces for efficiency production of alumina (AL2O3 ) technical. aluminium and some all.oys on the base of the high temperature carbon- thermal reduction process. At this case power consumption for production of unit of last, product will be less at the 3-4 times.The carbon-thermal method is allow produce alumina (Al203 ), technical Al and its alloys not only from deficient bauxites, but practically inexhaustible reserve of other types of Al-contain row materials (cianite, sillimonite and so on/The thermal-chemical economical analises of fulfilled at the IVTAN, production of alumina. Base on facts of production and technical technology are especially for ones arguments at the high temperature shaft-furnace technical Al and its alloysIn the last decades of the 20-th century, the discharge into atmosphere of high temperature and. combustion gases places . problems before humanity more and more sharply and becomes of great importance task.But at the same time, as production of material values increases, intensity of pollution of environment increases all time. And the value of new processes and. technologies of material production, aimed at reducing the expenditure of power and pollution of· the environment, also increases."

Jan 1, 2000