Search Documents

By Dhanesh Chandra

Long term stability studies were conducted on four variants of LaNi5; 10,000 hydriding/dehydriding cycles were used to evaluate their suitability for a metal hydride cooling system. Thermodynamic and structural studies were conducted to determine changes in these materials during cycling test period. The hydrogen sorption properties of LaNi5.2, and Lao 9Gd0.1Ni5 and LaNi4.75In0.27 were seriously degraded during the tests but the LaNi4.8Sn0.22 hydride was virtually unaffected. Hydride isotherms were measured at the beginning and at intervals through out the test period to observe the nature and extent of damage degradation in the sorption properties. X-ray diffraction studies of the alloys (LaNi5.2, LaO.9Gd0.1Ni5 LaNi4 8Sn0.22) and their respective hydride, before and after test, provided insight with regards to the observed changes in the hydride properties. Electron microscopic studies were also conducted to evaluate the changes in particle sizes.

Jan 1, 1989

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

The Dy-Nd-Pr-Ni alloy sample was prepared by cathodic potentiostatic electrolysis at 0.65 V (vs. Li+/Li) for 1 h using a Ni plate in a molten LiCl-KCl-DyCl3-NdCl3-PrCl3 system at 723 K. The highest mass ratio (Dy/Nd+Pr) in the alloy sample was observed to be 50 at 0.65 V. Anodic potentiostatic electrolysis at 2.20 V for 12 h was conducted using the Nd-Fe-B magnet electrode in a molten LiCl-KCl system. All elements were almost dissolved from the magnet, and the original form of the magnet disintegrated. After anodic potentiostatic electrolysis at 2.20 V, cathodic potentiostatic electrolysis was conducted at 1.00 V for 5 h using a Mo plate in order to remove the dissolved Fe from the bath. Finally, cathodic potentiostatic electrolysis was conducted at 0.65 V for 12 h using a Ni plate. The mass ratio of Dy/Nd in the alloy sample was determined to be about 18.

Jan 1, 2015

By Zhenyang Wang, Yiran LIU, Xiangdong Xing, Jianliang Zhang, Zhengjian Liu

Basic characteristics of marine placer were systematically studied by chemical analyze, scanning electron microscope and X-ray diffraction in this paper. It could be found that the marine placer mainly consists of titanomagnetite and titanohematite. A series of experiments were performed to investigate reduction-magnetic separation for Fe and Ti from the marine placer. Effects of reduction temperature, reduction time, carbon ratio, magnetic density, and grinding fineness on the reduction-magnetic separation process were investigated. And the optimal process parameters were obtained as follows: the reduction temperature 1300, the reduction time 30 min, the carbon ratio 1.1, the magnetic density 50mT, and the grinding fineness of 0.074μm 86.34%. Under such conditions, the metallization rate, iron grade of magnetic substance and iron recovery reached to 94.23%, 97.19% and 90.28% respectively, and the titanium grade in non-magnetic substance and recovery of was 57.94% and 87.22% respectively. The effective separation of iron and titanium could be achieved in reduction-magnetic separation process.

Jan 1, 2015

By A. J. Duncan, S. Viswanathan, Q. Han

"Measurements of liquid permeability in the mushy zones of Al-15.42% Cu and Al-8.68% Cu alloy samples have been performed isothermally just above the eutectic temperature, using eutectic liquid as the fluid. A modified method has been developed to determine the specific permeability, Ks, as a function of time during the test from the data collected on these alloys. Factors affecting permeability measurements are discussed. Permeabilties are observed to vary throughout the experiment. This is attributed to rnicrostructural coarsening and channeling that occurs in the sample during the experiment. The permeability is related to the rnicrostructure of the sample using the Kozeny-Carman equation. The correlation between the measured Ks, liquid fraction, gL and the specific solid surface area, Sv, improves markedly when compared to previous studies in which rnicrostructural coarsening was ignored.IntroductionThe permeability of interdendritic liquids flowing through dendritic structures ·is an important parameter needed to predict the level of porosity in castings. The permeability is a component of Darcy's Law, used to estimate the pressure drop due to the resistance to the flow of interdendritic fluid to feed shrinkage. Therefore, much research has focused on measuring the permeability of alloys in the mushy zone (1-10). The Kozeny-Carman equation for liquid permeability in the mushy zones of alloys may be written as"

Jan 1, 1999

By F. Mucciardi

With the increasing trend to continuous smelting and converting, granulation of copper matte is gaining prominence as a means of decoupling the smelting and converting operations. Moreover, granulation is also being seen as a possible avenue to using higher grade oxygen in converters. By feeding cold solid matte, the oxygen concentration can be increased to compensate for the lower enthalpy feed. This leads to a higher grade of SO2 in the off gas and a lower total flow rate. Current granulation technology relies on the cooling of a falling matte film by water jets. This technology while effective has several drawbacks including those related to safety. Noranda and McGill University have developed a new process (patent pending) for solidifying copper matte (or slag). It overcomes many of the negatives of current technology. The system is based on an air cooled twin roll caster. This: new system uses no water and instead incorporates heat pipe technology to transfer the heat from the solidifying matte to the cooling air to produce a thin strip of 1 to 2 mm in thickness. Testing of a prototype unit demonstrated its viability. This paper describes this newly developed, twin roll casting system that is completely waterless. The advantages of this process as well as the findings from several tests are also detailed.

Jan 1, 1999

By Laurentiu Nastac

"The importance of investigating solute redistribution during the unidirectional solidification of multi-component alloys is broadly discussed in the literature. A previously developed analytical model that was experimentally validated for Al-Cu, Sn- Bi and Fe-Si dilute binary alloy systems is used in this article to study in detail the solute redistribution, the liquid/solid interface stability based on an extended transient constitutional undercooling criterion and the size of the initial transient region during the unidirectional solidification of Ti-6-4 and Ti-17 alloys. A comparison between Ti-6-4 and Ti-17 alloy systems with respect to interface stability and the size of the initial transient region is also provided. The effective partition coefficients of the alloying elements in these alloys were determined based on specially designed experimental measurements.IntroductionThe importance of investigating solute redistribution during alloy solidification is broadly discussed in the literature [1-5]. One of the relevant applications of this study would be the mathematical modeling of equiaxed and columnar solidification of multicomponent alloys. This includes the instability of the solid/liquid interface. There are several mass and heat transfer processes that involve the calculation of solute redistribution during directional solidification such as industrial directional solidification processes, continuous casting, remelting processes, Czochralski crystal growth technique, floating zone techniques, etc."

Jan 1, 2012

By Daniel Kim, Michael Free, Justin McAllister, Urian Marshall, Shijie Wang

"Cathode impurity levels of electrorefined copper were evaluated based on 1/10* scale laboratory electrorefining tests. Cathodes were evaluated near the top, mid-section, and bottom sections of cathodes on both the set and mold sides and strip and scrap cycles. Slime weights were measured, and slime and electrolyte samples were also evaluated for impurities. Results from these tests have been compiled and compared to evaluate the effects of changes in operating conditions and electrode location on cathode impurities.IntroductionMany types of impurities are commonly found in commercial copper electrorefining anodes. The smelter operations that produce the anodes process concentrates that contain a wide variety of impurities that vary based on the mineralogy of the ore. Most anode impurities are removed during electrorefining. However, a portion of the anode impurities is incorporated into the copper cathode product. The mechanisms by which impurities are transported from the anode to the cathode are not well understood. Some impurities can be transported as anode slime particles to the cathode where they are incorporated into the cathode. Other impurities can be transported as dissolved species that are electrochemically reduced with the copper to become part of the cathode. Although research has been performed on anode slimes and impurities [1-4], there is a need for additional information regarding the relationships associated with electrorefining cycles, electrode faces, local electrode positions, anode impurities and specific cathode impurities. The objective of this study was to evaluate lead, arsenic, and antimony cathode impurity trends associated with electrorefining cycles, electrode faces, local electrode positions, and anode impurities. A variety of techniques including electrolyte filtering, anode heat treatment, high electrolyte arsenic concentration, high arsenic and/or lead in anodes, flocculation of slime particles, and appropriate current density control were used to vary cathode impurity levels. Each test was performed only once for a strip cycle and once for a scrap cycle. Consequently, the results for the individual conditions are preliminary and are not the focus of this study. However, the collective set of data with varying impurity modifying techniques provides a broad range of impurity levels, and the associated trends with respect to lead, arsenic, and antimony are discussed in this paper. Approximately 180 analyses of copper cathode were used to track the antimony, arsenic, and lead impurities. Eighteen anode slime samples were also analyzed for antimony, arsenic, and lead."

Jan 1, 2012

By Y. Takasaki

For zinc hydrometallurgical extraction, reducing the electric power consumption of the electrowinning process is an important issue for energy savings. At the Zinc & Lead 2000 symposium, the authors suggested that by using the Pb-0.5%Ag-0.6%Ca alloy, the electrolysis energy can be decreased compared to the conventional Pb-0.9%Ag alloy. In this study, the corrosion behaviors of the Pb-Ag-Ca electrode in a sulfuric-acid electrolyte were investigated. Based on the results Or me Pb-0.5%Ag-0.6%Ca anode after 20 days of electrolysis, the bath voltage and the quantity of anode slime decreased compared to the Pb-I%Ag anode. Subsequently, beta-PbO2 on the electrode surface was detected by XRD and its peaks were sharper than the Pb-1 %Ag anode. Moreover, a dense beta-PbO2 layer on the 0.6%Ca a anode surface was observed. Therefore, it was suggested that the dense beta-PbO2 layer on the anode surface is one of the factors that leads to a lower bath voltage and decreasing quantity of anode slime.

Jan 1, 2003

By K. Takahashi, G. Dodbiba, T. Fujita, N. Sato, S. Matsuo, K. Okaya

Different materials are used for manufacturing various parts of a cellular phone. Considering that a great number of mobile phones are being discarded every year, it is important to recover these materials and then recycle them in order to save resources. The primary objective of this work is therefore to find and suggest ways on how to recover various materials from discarded cellular phones for recycling. Much effort, for example, has been put in recovering and recycling tin oxide (ITO), a mixture of indium (III) oxide, (UI2O3) and tin(IV) oxide from the discarded liquid crystal displays (LCDs). Here we report a simple and cost-effective process, which includes a HC1 treatment process for altering the structure of the indium (III) compound into a chlorideinduced indium compound, in order to facilitate the vaporization of indium at a relatively low temperature. The experimental results indicated that 96.2 % of indium can be recovered from ITO, when the sample was heated at 973 K for 90 minutes. In addition, some thermodynamic calculations were also carried out in order to better understand the mechanism for chlorideinduced vaporization of indium.

Jan 1, 2011

By Kandipati Sreenivasarao

Ion flotation is a promising separation process for continuously removing toxic metal ions from dilute process effluents. After treating the effluent with appropriate surfactant(s), the metal- bearing species adsorb onto the surface of rising gas bubbles and can be collected as foams. Suitable collectors have been identified for most of the elements of the periodic table. However, a better understanding of the thermodynamic, kinetic and engineering principles that determine the performance of ion flotation systems would facilitate commercial utilization of this technology. A model system of sodium dodecylsulfate-ethanol has been studied for the removal of Cu (11) from dilute solutions, using laboratory-scale flotation columns. This paper reports the effects of the air flow rate, solution height, foam drainage zone height and col1ector:metal ion ratio on the flotation kinetics, ultimate recovery of metal, flotation product grade, foam losses and effluent quality. Preliminary results for Pb (11) removal are also reported.

Jan 1, 1993

By Lincoln McCrabb

Correct measurement and interpretation of viscosity data is critical for design of any thickening and pumping process that involves a non Newtonian slurry. The nickel laterite pressure acid leach (PAL) process relies on producing a slurry of maximum achievable solids concentration. Small variations of 1-2% solids concentration can alter economics significantly. For the Ravensthorpe Nickel Project, a rheology protocol has been developed which optimizes the solids concentration across a range of ore types. The vane yield stress technique has been utilized to accurately quantify the flow of thickened slurry in the lower shear range. A yield stress of 100Pa has been used as a benchmark to determine the optimum solids concentration achievable utilizing deep cone thickening. Statistical analysis of the data shows critical rheology distinctions between ore type, particle size, lithology and geochemistry. Linear and power law models have been applied to rheology flow curves to reconcile the material transport properties with the anticipated thickener underflow solids concentration. Keywords: Vane Yield Stress, Thickening, Rheograms

Jan 1, 2004

By Chai Liyuan

This paper focused on the preparation of porous ceramic pellets for microorganism carriers. A new method for the process was developed using simple gel-casting and bubble-in-water-in-oil type of multiphase double emulsion. The globules, consisting of a foamed sepiolite slurry suspension, were dispersed and consolidated in spherical shape in liquid paraffin as gelation progressed. The green pellets were sintered at 1100°C. The influence of surfactants, extension ratio and impeller revolution rate on the process and characteristics of the pellets was investigated. The pellet size was in the range of 1~4mm and determined directly by impeller revolution rate. The fine cell diameter of porous ceramic was in the range of 100~500m and the micropore diameter was less than 5m. The inner macropores were interconnected and extend to the external surface. It is impossible to analyze a result by SEM micrographs and digital camera.

Jan 1, 2006

By L. Béjar-Gómez

The aim of this research work is to study and characterize precipitates in structural microalloyed steel by transmission electron microscopy and analysis by high resolution (HRTEM). Microalloyed steel with titanium was produced by casting in an electrical induction oven of 25 Kg. capacity. Carbon content in steel was less than 0.1 % and titanium content of 0.04%. Steel was processed thermomechanically; reheated to 1250ºC and hot rolled on a laboratory mill to a 13.0 mm thick plate with a finish rolling temperature of 900ºC and thickness reduction of 80%. Analysis by High Resolution Transmission Electron Microscopy (HRTEM) identified precipitates in the steel; type and morphology. Energy Dispersive Spectroscopy (EDS) analysis was applied to obtain the chemical composition of precipitates and the matrix. STEM-EDS analysis was also applied to obtain the element profile of precipitates. The results showed the presence of carbonitride precipitates of titanium, Ti (CN), with a circular morphology and size of 10 nm and less.

Jan 1, 2006

By P. Hajiani

Rare earth elements (REEs) are critical materials in many leading-edge technology products. However, REE separation outside China has remained a challenge in addressing environmental concerns of current production. The author has worked on a technique employing the emphasised variability in the electrophoretic mobility (μi) of REE for the purpose of REE separation. In continuation of the results presented in IMPC 2016 [1], this contribution summarizes the progress achieved in 2016 and 2017. The major goal was to increase the REEs concentration by a factor of 1000 and to attenuate the consequent drawbacks, specifically joule heating effect. Amphiprotic hydroxylic solvent was selected to replace water, which has a major impact on the complexation mechanism and buffer requirement. Non-aqueous media result in a significant drop in the specific molar conductivity of the electrolyte, whilst μi reduces several times only. Moreover, a quasi-steady state electrophoretic separation in conjunction with temperature gradient focusing is adapted to improve scalability.

By Kunibert Hanusch

Copper in recycling material is accompanied by various groups of metals: 1) Metals which are much more negative than copper, such as Fe, Al, Si, P, Be They are mainly removed by fire refining during the recovery of copper and leave the process in form of slag. 2) Metals which are more positive than copper or difficult to separate by fire refining and which are partly reduced together with the copper. These metals are for example As,. Sb, Ni, Ag, Pb, Zn, Sn. They are enriched in intermediate products and recovered from these or remain for their major part in the fire-refined copper and can be separated by electrolytic refining and recovered from the electrolyte or anode slime. This report describes the process of Hüttenwerke Kayser AG in Germany and illustrates how considerable returns of material are partly required to separate or recover associated metals. They are finally removed in saleable products.

Jan 1, 1995

By Stephan Mulch, Christian His, Patrick M. Stephan, Thibault Champion

"When fuel costs increase dramatically, waste to energy (WTE) conversion technologies become a good alternative to produce energy. The potential energy available in domestic wastes, in developed countries, could be upwards of 4% of their total energy needs. Due to low energy recovery and low level of treated domestic wastes in many countries, the energy coming from waste is generally less than 0.5% of the country needs.Domestic waste incineration can convert heat to electricity for industry and housing and allow waste volume reduction in countries where land fills are a scarce resource.There is a request to improve existing combustion technology by increasing energy recovery with better heat transfer in the boiler and also by increasing lining durability with more resistant materials and technologies.The knowledge of corrosion phenomena and material performance allows Saint-Gobain Group to develop and propose high performance refractory lining solutions.IntroductionThe interest in alternative energy has been growing dramatically in the two last decades due to several combined factors, such as global energy demand, fuels prices evolution (e.g. crude oil, Figure 1) or environmental and geopolitics factors"

Jan 1, 2008

By L. Trincado

Mantoverde is a heap leach-SX-EW plant that was commissioned in December 1995 at a production rate of 42,130 ton of copper per year and 5.4 million ton of ore per year. Copper production has steadily been increased to 57,290 ton in 2002. Forecast copper production for 2003 is 60,000 ton for an ore treatment rate of 8.5 million ton. Several improvements in the heap leach process have been implemented. The main process improvements are related to the optimization of heap height, particle size, irrigation rate and leach cycle, in addition to a better heap drainage design and a solution management system. A first dump leach operation was started in 1999 at a production rate of 1,922 ton of copper. A second dump leach operation was started in early 2002 at a production rate of 2,805 ton of copper. Dump leach production will be increased over time to as much as 24,000 ton of copper. The main heap leach process improvements, as compared to the original plant design, as well as the main dump leach operating parameters are discussed in this paper.

Jan 1, 2003

By Ma Keyi, Yang Xianwan, Zhu Xiaoyun, Guo Zhongcheng, Zheng Yanping

"The oxidation of the Multifunctional Electrodeposited RE-Ni-WP- SiC Composites at high temperature is investigated. The results show that during high temperature oxidation the relationship between the mass change of pure Ni , Ni-W-P, Ni-W-P-SiC or RE-Ni-W-P-SiC coating and the oxidation time follows a mixed curve, i.e. it is approximately a linear relationship when the oxidation time is less than 60 mins while it is a power function relationship when the oxidation time is over 60 mins. The order for the oxidation rate of the four coatings is Ni> Ni-W-P> Ni-WP- SiC>RE-Ni-W-P-SiC. The mass change of Ni-W-P, Ni-W-PSiC or RE-Ni-W-P-SiC coating increases exponentially with a rise of oxidation temperature. The high temperature-oxidation resistance of RE-Ni-W-P-SiC composite coating is 3-4 times that ofNi-W-P alloy coating. The cross section morphologies and Xray diffraction patterns indicate that the high temperature oxidation resistance of RE-Ni-W-P-SiC composite coating is better than any other coatings.1. IntroductionWith the rapid development of modem industries the products in engineering industry are continually challenged by the requirements of long-term and stable working at higher temperature, pressure, speed and under adverse conditions. Consequently, the surface properties of the products, such as the resistance to oxidation at high temperature, the resistance to wear and the resistance to corrosion, should be improved continually."

Jan 1, 2000

By Tatsuro Ariyama, Michitaka Sato, Atsushi Sakai, Sumiyuki Kishimoto, Ryota Murai

"In order to achieve high pulverized coal injection operation in a blast furnace, optimization of the injection lance arrangement was carried out using an experimental furnace and mathematical models. To increase the injection rate of pulverized coal, it is required to raise the combustion efficiency of pulverized coal. It became clear that multi-point injection and the lance arrangement to avoid interference among the coal streams injected were so effective in increasing combustion efficiency. With these findings, the eccentric double lance arrangement has been newly developed.At NKK, Fukuyama No.4 Blast Furnace, after the improvement of the lance arrangement, the maximum injection rate reached up to 230 kg/thm and an average monthly record of 218 kg/thm was successfully achieved.IntroductionFrom the viewpoints of reducing the production cost of pig iron and prolonging coke oven life, high pulverized coal injection over 200 kglthm is actively pursued by ironmaking industries[1-2].Coal particles injected into the blast furnace are consumed by combustion in the raceway and also in-furnace reaction like solution-loss reaction (C + CO2 = 2CO). The amount of coal consumed by the latter process is determined by the carbon balance in the blast furnace and there is a limit. Therefore, to increase the injection rate, it is desirable to improve the combustion efficiency in the raceway. For these purposes, the optimization of the lance arrangement was examined by a hot model and mathematical models."

Jan 1, 1996

By Dhanesh Chandra

In this symposium, research in the area of energy conversion is presented. This symposium has special significance, as we honor three prominent scientists from hydrogen storage research and development field. In this symposium, the majority of papers presented by international scientists and engineers are in the area of hydrogen storage. Other energy conversion papers include magnetic materials, superconductors, and thermal energy storage materials. Recent developments in light-weight high gravimetric hydrogen density hydrides have led to potential use of hydrides for onboard automobile and other applications. This, of course, is significant from environmental concerns of CO2 and other emissions from the current use of carbon based fuels in automobiles. Thus, it is becoming increasingly important to switch to cleaner alternative fuels such as hydrogen [1]. The Challenge of Vehicular Hydrogen Storage as potential hydrogen energy carriers for vehicular applications, with a driving range of approximately 300 miles, require ~5-13 kg of hydrogen stored on-board. In the United States, Centers of Excellence have been established in metal hydrides, chemical hydrides, and carbon-based materials, and abundant scientific and industrial research is being carried on metal hydrides; only some of the current research from the Centers will be reported here. The European commission, Japan Institutions, and others also have numerous hydrogen storage programs in progress. Several international collaborations have also begun between IEA and IPHE scientists to accelerate the progress of development of practical hydrides. A summary of the abstracts is included in this overview.

Jan 1, 2006