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By Lijuan Li, Xin Xia, Junjun Huang, Qijie Zhai, Xiang Jiang

"Some experiments with different temperatures (1173, 1223, and l273K) and different annealing times (3, 4, 5, 6min) were carried out on cold-rolled plate of Fe-36Ni invar alloy. The microstructure and the mechanical properties were observed and tested respectively, and the fracture morphology was observed by SEM. The results show that with increasing of the temperature and the annealing time, the austenite grains gradually grow up accompanied by a small amount of annealing twin crystals, meanwhile, its plasticity and toughness are improved, and it is typical ductile fracture under the condition of tensile failure. After annealed at l223K, the invar alloy has better comprehensive properties than that at the other annealing temperatures, and the grains size is more uniform. Furthermore, when the annealing time is 4min, the invar alloy has the best comprehensive properties.IntroductionAs we known, most metals and alloys expand with increasing temperature. More than one hundred years ago (in 1897), Guillaume observed that Fe-Ni alloy with face-centered cubic (fcc) crystal structure, consisting of36%Ni, showing a very small thermal expansion coefficient below the ferro-to-paramagnetic transition, the thermal expansion coefficient around room temperature( <2 X 1O-6K-1 compared to most metallic materials which have a thermal expansion coefficient of 10-20 X 1O-6K-1) [1,2]. Since then, the subject has attracted many researchers, and various alloys with low thermal expansion coefficients have been developed. These alloys, generally known as ""invar alloys"", are in demand where dimensional changes due to variation in temperature must be minimized and where high stability is required [3, 4]."

Jan 1, 2012

By M. S. Moats

A considerable amount of research has been conducted to determine the causes of anode passivation. Chemical and electrochemical reactions that occur after passivation have received little attention. Chronopotentiometry, linear sweep voltammetry, cyclic voltammetry, and impedance spectroscopy have been used to elucidate three reactions that occur after passivation of commercial copper anodes. These involve the dissolution of silver and subsequent cementation and transformation of selenides, the oxidation of lead sulfate to lead oxide, and oxygen evolution. The amount of silver dissolution depends on the silver content of the anode, the time to passivation, and the molar ratio of Ag/(Se+Te). The oxidation of lead from PbSO4 to PbOx explains a potential plateau of oxygen evolution. Silver affects the duration of oxygen evolution on the PbOx. Anodes containing kupferglimmer display a characteristic oxygen evolution potential. It is believed that kupferglimmer provides a lower overpotential for oxygen evolution than the other slime phases or passivated surface.

Jan 1, 1999

By Qingwei Qin, Ping Xue, Guangqiang Li

Ausmelt furnace slag contains about 0.9% Cu (mass %). With increasing the amount of Ausmelt furnace slag, the recovery of copper from it will produce an enormous economic yield. The recovery of copper by floatation from slow cooled Ausmelt furnace slag was studied in this paper. The phases and composition of the slow cooled slag were analyzed. The factors which affected the copper recovery efficiency such as grinding fineness, pH value of flotation medium, different collectors and floating process were investigated. It was shown that the size distribution of the primary grinding and secondary grinding of middling were 75% for particles less than 0.074mm and 82% for particles less than 0.043mm respectively. The closedcircuit experimental results with butyl xanthate as collector in laboratory showed that the copper grade reached 16.11% and the recovery rate of copper reached 69.90% and the copper grade of tailings was only 0.2%.

Jan 1, 2015

By Gunther Schimmel

Ag exudation in four different alloys (Ag-Cd, Ag-Sn, Ag-Sn-In and Ag-Zn) is characterized. The amount of exuded material is correlated with the volume increase due to oxide formation in dependence of the alloy concentration and different densities of the oxide and matrix phases. It is shown that all four alloys show similar amounts of volume increases, but different amounts of exuded material. It is concluded that internal stresses due to the volume increase cannot be the dominant driving force for Ag exudation. A gradient in the chemical potential of Ag that originates from the O concentration gradient inherent to internal oxidation is suggested as driving force. The exudation behavior is thus governed by the variation of the activity of Ag in the Ag fcc phase in the Ag-Me-O system that differs between the alloying systems.

Jan 1, 2010

By V. Jiricny

The novel spouted-bed electrode (SBE) is a cathode system where copper is deposited at a high current density in a moving bed of copper particles. Preliminary results on the deposition of copper from acidic sulfate electrolytes using this novel cathode system were described during Copper &apos;95 conference. Despite a high current density, the electrical energy consumption was equal to or lower than that in the conventional electrowinning. The present paper describes more investigations on SBE. The SBE consists of copper particles with approximately 1 mm diameter onto which copper is deposited from acidic sulfate electrolyte whose composition is similar to conventional electrowinning. Three types of anodes were used in conjunction with the spouted-bed cathode, namely, DSA anode for oxygen evolution, and two novel anodes. One anode is less expensive than DSA; however it showed much promise in energy consumption. At a superficial current density of 2200 A/m2, the energy consumption was around 1.0 kWh/kg copper. The research activities described in this paper were supported by BHP Copper.

Jan 1, 1999

By Jim Hardy, Tim McKnight

"The thermal mass flow controller, or MFC, has become an instrument of choice for the monitoring and controlling of process gas flow throughout the materials processing industry. In the semiconductor industry, these MFCs are used on over 70% of the processing tools. Reliability and accuracy are major concerns for the users of the MFCs. Calibration and characterization technologies for the development and implementation of mass flow devices are described. Sources of inaccuracy in process gas handling are described, and a model to correct for these inaccuracies is outlined. A gravimetric calibrator is described that allows flow sensors to be calibrated in corrosive, reactive gases to an accuracy of 0.3% of reading, at least an order of magnitude better than previously possible. All described capabilities are implemented in a Department of Energy User Facility which is available to industry and universities to test and develop gas flow sensors and controllers and evaluate their performance related to environmental effects, reliability, reproducibility, and accuracy.IntroductionMaterials processing is at the heart of semiconductor manufacturing. To make today's advanced integrated circuits, silicon wafers are subjected to over 200 process steps. Most of these steps involve processes such as etching, implanting, diffusion, annealing, deposition, and lithography (resist deposition and hardening). Often one or more process gases are used to complete the process step. To achieve the quality and performance required in the micro devices, accurate measurement and control of these gases is essential. The Oak Ridge National Laboratory (ORNL), in conjunction with the semiconductor industry, has been working to improve process gas measurement and control accuracy and reliability. Standardized test methods have been developed to characterize and benchmark the performance of mass flow controllers (MFCs), the method of choice for monitoring and controlling gas delivery. Testbeds have been designed and fabricated to produce repeatable and accurate data using these standards. Baseline testing was performed along with development of a unique mass flow instrument, the gravimetric calibrator."

Jan 1, 1997

By Mostafa O. El-Bealy

"To estimate the interdendritic cracking tendency in casting processes, a new model for interdendritic cracking criteria has been proposed. The model combines a concept of the alloying element effect on the interdendritic strain generation and therefore on the susceptibility of interdendritic cracking phenomena. A susceptibility of interdendritic cracking is modeled by using El-Bealy's interdendritic cracking susceptibility function ""BJCSF' and the opening displacement between the dendrites ""EIA "". These concepts are modeled based on the previous experimental observations and ElBealy' approach. The model is implemented numerically for a one-dimensional model problem with some similarities to the casting of steel. The variation of some key parameters that are known to influence the frequency and severity of the interdendritic cracking is then studied.I. INTRODUCTIONInterdendritic cracking ""hot tearing"" commonly encountered in both ferrous and nonferrous castings (1,2]. It is generally believed that interdendritic cracks start to nucleate and develop in the interdendritic strain region within the mushy zone [l-5]. The interdendritic strain region is then definitely coherent, but continuous films of liquid still exit (4,5]. This distinguishes interdendritic cracks from cold cracks forming during the casting process after complete solidification (6,7].Much effort has been put into the understanding of the interdendritic cracking phenomena, and several theories have been proposed. Fellini [8] stated that interdendritic crack ""hot tear"" will result if the material is subjected to too high of accumulated strain within so called vulnerable part of the solidification interval. Kinosita et. al. [9] and Campbell (10] also emphasized the role of tensile stresses in the forming of interdendritic cracks. Most interdendritic cracks criteria simply consider the size of solidification interval, stating that solidification range is associated with a lager interdendritic cracking susceptibility than a short range. Clyne and Davies (11] formulated a more refined such criteria based upon the time spent in different regimes of the solidification interval. They defined a vulnerable region in which thin continuous films of interdendritic liquid exist, and the permeability is low. When thermal strains are induced in this region, the film is not able to sustain the stresses, and an interdendritic crack will form."

Jan 1, 2001

By E. M. Weenink

A proposed alternative to the conventional zinc extraction processes is the flash reduction of zinc calcines. As part of an overall study of this process, the kinetics of single zinc oxide pellets were investigated. Pellets, compacted from Outokumpu zinc calcine (60.9% zinc, 9.6% iron), were suspended in a flow of CO/CO, mixtures and reduced at temperatures between 1000 and 1200°C and atmospheric pressure. The pellet weight loss with time was recorded and analyzed. It was found that the reduction of calcine pellets (0.9 cm height and 1.36 cm diameter) was controlled by chemical reaction. This paper includes an analysis of the experimental results of two previous investigations of ZnO reduction.

Jan 1, 1992

By Norimasa Yamasaki, Masao Kurosaki

"The effects of plating conditions on the crystal orientation of electrodeposited zinc were investigated by varying elecyrolyte flow rate and current density. Precipitation of the Zn (00 • 2) basal plane is promoted at lower current density and higher flow velocity. Effect of the flow velocity on the mass transport was evaluated based on the polarization measurement in which Cu was used as the tracer. As a result, it has been clarified that the crystal orientation of electrodeposited zinc can be uniquely arranged by the overvoltage (iU0.5) that can be simply calculated by considering -the current density and boundary layer thickness. At the same time, the electrode potential during electrodeposition that can be calculated by using a model based on the competitive reactions of hydrogen reduction 'and zinc reduction exhibits an extremely good correlation with the crystal orientation of electrodeposited zinc.Introduction Electrogalvanized steel sheet has better surface properties than hot-dip galvanized steel sheet, and is used in home electric appliance and automobile applications. Factors such as crystal morphology, crystal orientation and surface roughness have a large influence on its appliance, formability and corrosion resistance [1-3].Electrolysis, condition, bath composition and alloying elements are reported as factors that affect the crystal orientation of the electrogalvanized coating. Factors that can be controlled on time in the production site are electrolysis condition that-is current density and plating solution flow velocity.Some studies[4-6] report that the crystal- orientation of the Zn(00 • 2) plane is increased by promoting, the mass transfer of zinc ions in the plating solution or decreasing the concentration overvoltage, but did not investigate in detail the plating solution flow conditions in the plating cell nor quantitatively determine the effects of both current density and plating solution flow conditions on the crystal orientation of ' electrodeposited zinc."

Jan 1, 2000

By Jukka S. Sulanto

Outokumpu has applied its well -known copper Fl ash Smelling Process also for smelting su1phide lead . concentrates. The lead in the Flash Smelting Furnace slag is recovered by reducing the oxygen potential of the slag in an electric furnace by injecting reductant into the slag bath. A series of tests have been carried out in a 1000 KVA electric furnace? adjacent to a pilot Flash Smelting Furnace. The furnace has been fed continuously with molten Flash Furnace Slag. The feed rate has varied from 0.5 to 3.1 MTPH (0.55 - 3..4 STPH) depending on the feed rate and the quality of concentrate to the Flash Smelting Furnace. The inlet slag contained 15 to 40% of lead and the cleaned slag 1. 5 to 3. 0%. The lead recovery from sol id raw material was tested in the same continuous process by feeding lead calcine into the furnace. Feed rate was 0.7 to 0.95 MTPH (0.8 - 1.05 STPH) and the calcine contained 33 to 34% of Pb. Several reduction agents and procedures were tested. The process proved to be suitable for continuous recovery of lead from solid oxide raw materials.

Jan 1, 1990

By Shun Fujieda, Shigeru Suzuki, Kozo Shinoda, Tetsuo Fujita

"Dowa Metals & Mining Co. Ltd. has developed and plant-practiced a unique scorodite synthesis technology (DMSP®) for arsenic immobilization by oxidizing Fe(ll) ions in the presence of As(V) ions. Dowa has improved the DMSP® technology and has developed the process extensively for other applications. This paper focuses on the applicability of the DMSP® for various cases of copper smelting, and introduces other technologies for fixing arsenic and recycling gallium from GaAs, simultaneously processing (fixing) arsenic and thallium, and fixing and recovering arsenic from dilute arsenic solutions. The DMSP® was found to be applicable not only for various processes in nonferrous smelting, but also for other applications with a high potential for reducing environmental problems.IntroductionDowa Metals & Mining Co. Ltd. developed a method for synthesizing scorodite at ambient pressure [1], The scorodite is precipitated by oxidizing Fe(II) ion in a high-concentration As(V) solution. The scorodite produced in this way does not readily release arsenic because of its high crystallinity. Dowa built a demonstration plant for this technology at the Kosaka Smelter and established the production of scorodite at 30 t As/month by treating intermediate products from copper smelting as the starting material. The DMSP® was demonstrated to be favorably applicable to copper smelting [2]. We are engaged in further increasing the amount of arsenic fixation by the use of this process. Further improvements in productivity, cost reduction and applicability in various processes have been devised. Dowa has been endeavoring to resolve other problems as well as to improve productivity. We have gained extensive knowledge on arsenic treatment in our endeavors, enabling us to solve problems and improve productivity. This paper introduces the investigations and developments related to DMSP®."

Jan 1, 2012

By N. Bazzanella

The hydrogen desorption kinetics of pure and Nb-doped magnesium hydride film samples was investigated by using a Sievert-type apparatus. The overall activation energy and the reaction order controlling desorption are (141±5) kJ mol-1H and n 4 for Mg hydride and (51±5) kJ mol-1H and n 1 for Nb-doped (5% at) Mg hydride indicating that, in the doped sample, hydrogen desorption is controlled by the H migration in transformed h-Mg layers. Structural analysis performed by X-Ray Diffraction (XRD) and Extended X-Ray Absorption Fine Structure spectroscopy (EXAFS) show that the catalytic effect of the Nb dopant is connected with the formation of NbH0.89 nanoclusters dispersed in the Mg hydride matrix. It is suggested that the catalysis process is also connected to the presence of Mg-Nb hydride interfaces where the transfer of H atoms preferentially occurs by connecting h-Mg grains and by the role of the MgH2-NbH0.89 interface as preferential site for the dissociation of the hydride phase.

Jan 1, 2006

By Leonard J. Friedman

The recovery of sulfur dioxide from metallurgical gases for the production of sulfuric acid has been an effective means of reducing sulfur dioxide emissions from non-ferrous smelters. Sulfuric acid has been produced from gas originating from fluid bed roasters, electric furnaces, reverberatory furnaces, flash smelting furnaces, Pierce Smith and flash converters, sinter machines, etc. The gas from each of these sources has a unique set of variables that affect the design and operation of the sulfuric acid plant. In addition, the sulfuric acid plant itself has been evolving, with new equipment designs and materials. This paper will review each of the unit operations in the gas cleaning and contact sections of the metallurgical sulfuric acid plant, discussing various equipment designs, materials and the handling of gas stream variables and impurities. The paper updates to 2006 previous works on metallurgical sulfuric acid plants by the authors.

Jan 1, 2006

By Roland Kammel

In combination with various physical and chemical methods also electrochemical techniques are most frequently used to improve the recovery of metals from aqueous dilute process streams or effluents e.g. in electroplating, metal finishing, mining and metallurgical plants. To insure cathodic metal recoveries with favorable current efficiency and high throughputs per unit of cell volume seve¬ral types of electrolysis cells have been developed comprising extended electrode surface areas and/or intensive electrolyte. agitation. The practical experiences with these units indicate especially for the electrolytic recovery of metals whose values are high, that the treatment cost permits profitable operations with relativly short payback periods for the units. Anodic reactions can be utilized for the removal of undesired anion contents or buildups of impurities. Appropriate combinations of these recovery methods are used to improve the versatility and the overall economy. Industrial applications reveal their potentional as addidtive techniques for existing processes to reduce the metal content of effluents to values that meet the guide lines of environmental legislation whereas integrated in-operation recovery methods are nowadays increasingly introduced to approach nearly close-loop operations.

Jan 1, 1992

By JiaPeng Xu, Brian Lo, Uday B. Pal, Yihong Jiang, Soumendra N. Basu

"The Solid-Oxide Oxygen-Ion-Conducting Membrane (SOM) electrolysis process has been successfully tested on a laboratory scale, producing silicon directly from silica in a cost-effective and environmentally friendly way. A yttria-stabilized zirconia (YSZ) tube, closed at one end was employed to separate the molten salt containing dissolved silica from a liquid metal anode placed inside the YSZ tube. When the applied electric potential between the liquid tin cathode in the molten salt and the anode exceeds the dissociation potential of silica, oxygen ions are pumped out of the molten salt through the YSZ membrane and oxidized at the anode while the silicon cations in the flux are reduced to silicon at the liquid tin cathode. The presence of high-purity silicon crystals on the surface of liquid tin cathode was confirmed by scanning electron microscopy (SEM) and energy dispersive x-ray spectroscopy (EDS). Silicon crystals were extracted from tin cathode by chemical etching.IntroductionPhotovoltaics (PV) generate electrical power by using solar cells, and dramatically reduce the emissions of greenhouse gases (GHG). Through 2006 to 2011, it grew the fastest of all renewable technologies with operating capacity increasing an average of 58% annually [l]. However, the cost of manufacturing solar-grade silicon (SoG-Si) for high-efficiency solar energy production represents a major barrier to achieving the industrial goal for solar power of $1/Wp (watt at peak exposure) which would enable widespread grid parity. The current contract price of silicon to PV manufacturers is $50-$60/kg, with the spot market in 2007-2008 showing prices as high as $300/kg [2]. This makes the development of low cost and environmentally friendly manufacturing of high purity silicon very important."

Jan 1, 2013

By Z. S. Wronski

In rapidly solidified Fe-Nd-B permanent magnet alloys, the content and distribution of Nd-rich intermetallic and Fe-phases determine coercivity Hc and remanence Br. Consequently, microstructure plays a crucial role in deter- mining the (BH) max-product of permanent magnets fabricated from these alloys. A study has been initiated to investigate changes in microstructure and the effects on magnetic properties as the material is processed from arc-melted ingot to melt-spun flakes and finally to a product consolidated by hot-forming. Anisotropic magnetization behaviour has been observed in rapidly solidified flakes after low-temperature annealing.

Jan 1, 1989

By K. S. Jeong

Since the start-up of the Onsan Smelter in 1979, LS-Nikko Copper has grown into a competitive smelter through continuous development. Several environmental improvements have been carried out, in particular, intensive investments in reducing SOx emissions, such as de-sulfurization plants, fugitive gas capturing and TMS(Tele Metering System). In addition, in recent years LS-Nikko Copper has spent more than 10 million USD every year to improve environmental conditions. In order to be a global leading smelter in every aspect especially environmentally, LS-Nikko Copper plans to inspire environment-friendly minds, co-operate with shareholders, and participate in global conventions. This paper describes the environment improvements carried out at Onsan and briefly introduces a sustainable vision for a green smelter.

Jan 1, 2006

By V. V. Geikhman

The paper updates the Plant experience in the development and implementation of an advanced environmentally friendly zinc production technology complying with the technological and economic level of producers in the world and the standards of maximum permissible gas emissions stipulated by the Russian legislation. General water recycling engineering allowed to ensure 95.6% water rotation level. All solid wastes formed during treating zinc concentrate are processed into marketable products or semiproducts and sold. As a result of implementing innovation techniques production at the Chelyabinsk Zinc Plant is non-waste.

Jan 1, 2006

By B. Yawney

A copper-nickel sulfide concentrate was leached in water at about 2000C under oxygen pressures of about 0.35 MPa. Oxidation of sulfide to sulfate was virtually complete in about 30 minutes, resulting in greater than 95% copper and 98% nickel extractions. Leaching temperature was shown to be the most important factor affecting metal extractions. Measured rates of oxygen consumption were used to develop batch kinetic data. Mini-plant continuous pressure leaching tests agreed with batch leach results. A proposed overall flowsheet is briefly examined.

Jan 1, 1976

By Mei Song, Qingyu Deng, Xuewei Lv, Lu Liu, Chenguang Bai, Meilong Hu

"The carbochlorination of several silica materials was carried out in the temperature range from 900 °C to 1200 °C. In this study, silica oxides and gaseous chlorine with carbon as reductant were used. The optimal carbon silica mole ratio in different temperature was calculated by Factsage software and the results showed that the optimal values are 1.2, 1.4, 1.6, 1.8 at 900 °C, 1000 °C, 1100 °C, 1200 °C, respectively. According to the experiments, the chlorination ratios of several silica materials were increased with temperature increasing. In the same temperature, the chlorination ratio of diatomite is the maximum and the chlorination ratio reaches 79%% when C/SiO2 reaches 3 at 1100 °C.1, IntroductionPolycrystalline silicon is the main material to manufacture the silicon polished section, solar battery[1] and high purity silicon wafers[2], also which is the most basic function material of semi-conductor industry, electronic information industry and solar photovoltaic battery industry[3]. The conventional manufacturing process of polycrystalline silicon would be divided into three parts: the improved Siemens method, which was introduced and became the main process to produce the polysilicon products in China. Silane method and fluidized bed method. Silicon tetrachloride and chlorosilans have been employed as by-products in several fields like electronic, telecounications and metallurgy[4-6]• At present, the main applications of silicon tetrachloride include production of trichlorosilane by catalytic hydrogenation, synthesis of fumed silica and ethyl orthosilicate, production of optical fiber grade silicon tetrachloride.The conventional routes for the silicon tetrachloride production have been reported, including the direct chlorination and the chlorination process of ferrosilicon, abandon catalyst and silica[7]."

Jan 1, 2013