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By P. N. Anyalebechi

A comparative study of the mechanical properties of automotive steering knuckles produced by three different shape-casting related processes has been conducted. It involved the characterization of the tensile and fatigue properties of aluminum alloy A356 knuckles produced by the vacuum/pressure riserless casting (VRC/PRC), pressure counter pressure casting (PCPC), and the hybrid Cobapress (a casting-forging) processes, in accordance with the appropriate ASTM standards. Surprisingly, the knuckles produced by the hybrid Cobapress process exhibited the lowest strength. For example, the average 0.2% yield strength of the Cobapress knuckles was 31 MPa and 40 MPa less than that of the VRC/PRC and PCPC knuckles, respectively. However, between stresses of 150-200 MPa, the fatigue lives of the VRC/PRC, PCPC, and Cobapress knuckles were comparable. But above 200 MPa, the Cobapress knuckles exhibited the lowest fatigue life. The observed differences in the mechanical properties are attributed to the inherently different microstructures of the different knuckles.

Jan 1, 2009

By P. M. Swash

The determination of the heavy minerals in beach sand samples is highly dependent on the preparation technique used. In this paper a simple reproducible method for the quantification of "recoverable" ilmenite, zircon, rutile and leucoxene by magnetic separation, is described. The procedure recommended yields information relevant to the metallurgical processing of the ore rather than to the total heavy minerals present in the samples. Finally the determination of mineral reserve estimations and grade assessments is greatly facilitated when this "mineral assay" method is employed. An assortment of other mineralogical methods are described including SEM, EMPA, XRD, XRF, Image analysis, Mossbauer. clerici and perm roll separations. The methods are briefly examined and the practical information that can be gained by using such techniques are reviewed. Experience has shown that an understanding of the relationship between the physical and chemical properties of the heavy minerals can contribute to the prediction of mineral particle behaviour. Such information may ultimately help reduce the prospect evaluation period and minimise expenditure on metallurgical testwork.

Jan 1, 1991

By Basant L. Tiwari

An electrolytic process, based on a three-layer concentration cell, to extract magnesium from commercial aluminum alloy scrap has been examined. The process was repeatedly tested at 1025 K with two cells of d1fferent sizes, 0.6 kg and 5 kg feed aluminum, to have a better understanding of the opera ting parameters and evaluate the scale-up potential. In both cells, the magnesium content of the scrap was selectively reduced ?from 1. 1 to less than 0.1 wt.% at anodic current dens-Hy as high as 1. 1 A/cm2 with current efficiency exceeding 85%. Magnesium was recovered in the form of salt coated globules. Comparison of performances for the two cells suggests that the process can be scaled up. With further development, this process could become a viable alternative for demagging secondary aluminum.

Jan 1, 1985

By Ravi Vancheeswaran

The consolidation of ceramic fiber reinforced metal matrix composites is a key process step in the synthesis of high performance composite systems. A simulation tool has recently been developed for predicting the evolution of the composites internal state microstructural variables (eg. relative density, fiber microbendinglfracture, and chemical reaction layer thickness at the fiber-matrix interface) during the consolidation processing of spray deposited composite mono-tapes. A Generalized Predictive Control (GPC) scheme is used in conjunction with the simula-tion tool to design near optimal process paths that minimize fiber damage and reaction product thickness while simultaneously maximizing the composites relative density. The microstruc-tural evolution depends nonlinearly on the process conditions and therefore the scheme uses a constantly updated linearization of the model to optimize the input process variable vector. A control simulation is presented to illustrate the performance of the design scheme and to assess the feasibility of its use for the achievement of goal state microstructures at the completion of consolidation cycles.

Jan 1, 1996

By David J. Kinneberg, Barbara E. Mangion, Arnold M. Savolainen

Analytical laboratories require a qualitative or semi-qualitative method of determining major and minor constituents in "unknown" samples to select optimal analytical techniques. This is exceedingly important in precious metal assay laboratories where the precision and accuracy requirements are exacting (routinely within 0.02%, absolute basis). This paper describes the use of an x-ray fluorescence spectrometer with a specially designed software package to select optimal analytical procedures and specify relevant analytical parameters. A wavelength dispersive XRF spectrometer is capable of quick and accurate analyses of properly prepared samples without extensive standardization. When coupled with a specially designed software package, this preliminary assay system is applicable to a wide variety of sample types including gold and silver bullion, karat gold and karat PGM alloys, high silver and high copper metallic samples as well as particulate samples of ores and sweeps. The system relieves the assayer of tedious calculations for silver inquartation and proofing, minimizes human error and standardizes selections over time. Most importantly, the system allows for independent verification of final assay results.

Jan 1, 1999

By Andreas Nolte

This paper includes a comprehensive report about the metallurgical utilisation of reusable products from electronic scrap recycling, car shredding industry, used glasses an various waste products, such as slimes and flue dusts, generated in a secondary copper smelter. Depending on the copper content, the type of copper compounds and the characteristics of accompanying substances, the materials are treated by smelting in furnaces, operating under reducing or oxidizing conditions. HKs pyro- and hydrometallurgical processes, blast furnaces, converters anode furnaces, tin lead alloy plant and tankhouse will be outlined. The reusable products are categorized according to the origin of the materials and then presented in the form of quantity and quality balances. Processing methods, process able quantities and quality requirements of inputs are described. The utilization degree of the most important metals (copper, tin, lead and zinc) is described with graphics. The report is rounded by information on operating licence according to the environmental regulations of the Federal Republic of Germany and data concerning supply and contracts

Jan 1, 1997

By Kumar P. Dharmasena, Haydn N. G. Wadley, Bill W. Choi

"Non-contact eddy current sensing methods have been developed and applied to Cd0.955Zn0.045Te crystal growth to obtain a better understanding of the melt, solid nucleation, and the growth process. The application of this sensor approach relies on a large difference in liquid and solid electrical conductivities near the melting point and requires knowledge of the relationships between the electrical conductivity, melt composition, and temperature. Using a multifrequency encircling eddy current sensor, the electrical conductivities of three different Cd1-xZnxTe (x=0.00, 0.045, and 0.08) alloys were measured as a function of temperature in a laboratory-scale vertical Bridgman furnace. The measured solid and liquid electrical conductivities were then used in electromagnetic finite element models to analyze the multifrequency responses of eddy current sensor designs during the simulated growth of a crystal. These eddy current sensors were fabricated and installed in a vertical Bridgman furnace and used to monitor many Cd0.955Zn0.045 Te growth runs. One sensor was placed in the vicinity of the ampoule tip to detect undercooling/spontaneous nucleation and two other sensors (""absolute"" and ""differential"" designs) placed to monitor the movement/curvature of the liquid-solid interface during crystal growth. The sensor data was used to characterize the initial melt state, detect the onset of nucle-ation, determine the growth velocity, and identify the shape of the interface.IntroductionSingle crystal CdTe and its solid solution Cd1-xZnxTe alloys (0.03<x<0.05) are used as infrared transparent substrates for infrared focal plane array (IRFPA) detectors [1-6] and as solid state y- ray detectors [7-9j. Cd1-xZnxTe substrates are normally ""mined"" from large polycrystalline boules grown by the unseeded directional solidification of Cd1-xZnxTe melts using either a vertical or horizontal Bridgman process [10-14]. The vertical Bridgman method is particularly popular for growing CdTe and its related compounds. In this process, a Cd1-xZnxTe ingot is produced by first melting a charge in the hot zone of the furnace and then vertically translating the furnace (with its associated axial temperature profile) relative to the stationary crucible to cause directional solidification. In spite of many experimental efforts to investigate the relationships between material purity, stoichiometry, the controllable growth parameters (furnace temperature profiles, ampoule geometries/materials, furnace translation rates and starting position) and the resulting material characteristics (grain structure, dislocation densities, IR transmission, macro-segregation etc.), the yield of Cd1-xZnxTe of a quality suitable for large area (e.g. 4 cm x 6 cm) substrates remains low (<10%). Since much of this poor yield is directly associated with the crystal growth process (e.g. melt stoichiometry, solidification velocity, interface shape, temperature gradients, cooling rate, etc.) intensive efforts are under way to improve this technology."

Jan 1, 1997

By Michael G. Mayer

Since its invention in 1859 various designs of lead batteries have evolved to meet commercial needs for traction applications and standby power. In recent years major developments have taken place in lead alloys and the chemistry and mechanical design of industrial lead batteries. These are reviewed in relation to their commercial application together with the new type of maintenance free gas re-combination lead-acid batteries which are opening so many new markets for lead.

Jan 1, 1990

By Louis J. Mittoni

"It is well known that gas injection systems can exhibit a wide range of dynamical behaviours, ranging from linear periodic bubbling through to highly complex turbulent jetting. Recently, it has been observed that an important intermediate regime exists under certain system conditions, where the dynamics are complex in nature yet predictable for short time periods. This paper reviews the evidence to support the above hypothesis, and discusses the invariant quantitative measures such as density, return maps, Lyapunov exponent and dimension which may be used as pattern recognition features in a mOnitoring and control strategy.INTRODUCTIONThere has been a great deal of research on the submerged injection of gases into liquids. This interest is primarily due to the large number of applications in the pyrometallurgical and chemical engineering industries. Gases are typically injected into liquids to achieve goals such as heat and mass transfer, or physical mixing and agitation. Only recently though has the possibility of using the evolution of the gas dynamics as a probe to internal system conditions been raised [1, 2].At very low gas injection rates and small upstream chamber volumes, gas normally disperses in the form of stable bubbles of constant volume [3]. With increases in gas flow rate, the dynamics become more complex, bifurcating into double bubbling, multiple bubbling and complex coalescence behaviour. Irregularities measured in pressuretime series acquired upstream of the injection port under these complex conditions have usually been treated as bothersome noise or contamination to be filtered from the signal and ignored in the analysis. These irregularities, however, may contain physically interesting and useful information on the system from which they were produced if the system may be classified as deterministically chaotic [4]."

Jan 1, 1996

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

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

Mar 1, 2017

By Manis Kumar Jha, D. D. Pathak, Archana Kumari

Treatment of secondary/waste to recover rare earth metals (REMs) is gaining importance due to its increasing global demand, lack of availability of high grade natural resources and huge generation of secondaries. Present paper reports the critical review on available processes for recovery of REMs from secondaries viz. manufacturing scraps, e-waste, industrial residues such as red mud, fly ash, waste water, etc. Hydrometallurgical processes with combination of Beneficiation/ Pyro-/Electro techniques are discussed to recover REMs effectively. The recommended processes require less energy to deliver high purity yield which is one step towards green environment. Salient findings on various methods are reported with recommendations which will be helpful to researchers working in the area of REMs extraction.

Mar 1, 2018

By B. R. Baldock

The converting of high-grade nickel matte for production of low-sulphur matte or nickel metal is a process which has eluded metallurgists in the past because of the limitations of conventional converting furnaces. The high temperatures required and the refractory nature of nickel oxide has prevented practical success in a process which has been known to be theoretically feasible for a long time. The Ausmelt top submerged lancing system is capable of operating under close control of the smelting conditions. High temperatures and both rapid oxidation and rapid reduction can be achieved. These features have provided the basis for successful pilot plant trials of the desulphurisation of high-grade matte from the Kalgoorlie Nickel Smelter. Sulphur level in product was lowered from 20 to 25% to as low as 0.2%, with iron levels in matte in the range of 1.0 to 3.5%. The theoretical background of matte desulphurisation is surveyed and the pilot plant operations described. The implications of the results in relation to commercial plants and possible refinery operations are summarised.

Jan 1, 1993

By Christopher M. Moore

DK Recycling und Rohelsen GmbH converts 380 000 annual tonnes of iron containing waste materials Into pig Iron. Zinc Is the main reason that these materials are classified as waste. The materials are processed In the conventional way by making sinter which is then smelted in a blast furnace to foundry grade pig iron. The trick lies not in the unit operations which are quite standard but rather In the modifications made to the plant and operating procedures to cope with the much higher levels of tramp elements.

Jan 1, 1995

By Robert E. (Bob) Brown

Magnesium was discovered by Davy in 1808. The production processes as they exist are not economically competitive with aluminum The electrolytic magnesium process is divided into two steps; one to make the MgCh feed and the other to apply large amounts of electric current to dissociate the feed into magnesium (450 g) and chlorine (1200 g). The production of fuJIy anhydrous, pure cell feed is a major problem Recently, there has been a growth of thermal processes, mainly the Pidgeon silicothermic production process using FeSi to reduce dolomite in horizontal retorts. Pechiney has a large vertical electrical furnace process that also uses FeSi to reduce calcined dolomite in a molten bath containing alumina. Work is proceeding to develop new or modified processes that will greatly improve magnesium production. The present methods and the research and R&D will be reviewed in this paper.

Jan 1, 2001

By Bo Björkman

Four different arsenic containing dusts from the Boliden plant, Boliden mineral AB, Sweden have been examined. A kinetic study of the As elimination was performed in a laboratory scale roasting furnace for roasting furnace ESP dust and smelting furnace ESP dust. Characterisation and thermodynamic calculations were carried out to determine the mineralogy, and the stability of compounds in the dusts studied. The characterisation methods used were chemical analysis, X-ray diffraction analysis and microprobe analysis. It was found in the experiments that a high degree of As elimination was obtained for roasting fumace ESP dust and a low degree for smelting fumace ESP dust. Derived kinetic models are given. A prediction of the As-elimation for settling furnace dust and converter ventilation dust is presented.

Jan 1, 1994

By P. N. Anyalebechi

"The effects of solidification rate, initial melt hydrogen concentration, and grain refining on porosity formation in aluminum alloy 2024 have been investigated with unidirectionally cooled laboratory-size ingots. The ingots were prepared from melts containing hydrogen concentration of 0.059-0.27 cm3/100 g and solidified at 0.2-37 °C/s. As expected, the amount of porosity, average pore size, and pore number density increased with increase in melt hydrogen concentration and decrease in solidification rate. However, the effect of solidification rate was greater at the very low melt hydrogen concentration (0.059 cm3/100 g). These results are consistent with reported effects of solidification rate and melt hydrogen content on porosity formation in other aluminum alloys. Interestingly, addition of grain refiner slightly increased the amount of porosity and the average pore size, especially at solidification rates above 1°C/s. IntroductionIn shaped castings and wrought products fabricated from ingots, billets, bars, or slabs of aluminum and its alloys porosity formation is a problem. This is because it compromises their tensile strength, fracture toughness, and fatigue properties [ 1-18]. The pores are usually the crack initiation and propagation sites [6,8,9] and the largest pores tend to dictate the fatigue life of the aluminum products [9,10,14]. Porous regions within an aluminum product probably yield first due to the reduced tensile load bearing capacity, causing the concentration of the strain near the voids which subsequently results in premature fracture. In aluminum alloy ingots, billets, bars and slabs porosity formation is particularly problematic because of its persistence through fabrication and potential for reappearance or exacerbation during subsequent thermal treatment processes before and/or after fabrication [19]. In fact, persistence of microporosity is a serious problem in large thick plates of wrought aluminum alloy products that must be rolled from correspondingly large direct-chill or electromagnetic cast ingots. Some of these thick plate products are machined into large aircraft components that are required in service to withstand multi-directional stresses and to possess high fatigue strength, fracture toughness, resistance to stress corrosion cracking, and strength in the short-transverse direction [1,20]."

Jan 1, 2011

By Viviane Tavares

The technology advance of mobile devices makes consumers of these equipment do more constant exchanges, with this the obsolete devices discarding becomes an environmental problem, due its landfill accumulation. In order to minimize the environmental impacts caused by these equipment there?s the recycling necessity of polymers, ceramic and metallic materials. The main goal of this recycling is to study the printed circuit board of device mobile processing through ore treatment in order to recoup copper. Initially printed circuit boards were processed in a knives mill, in order to liberate the ferrous material, after that it was done the magnetic separation of the reduced residue. With the not magnetic fraction it was done the grain sized analysis and sulfuric acid and hydrogen peroxide leaching analysis. With the chemical analysis results proceeding from the leaching aliquot it was possible to observe that the leaching method with sulfuric acid and hydrogen peroxide presented greater copper recovery.

Jan 1, 2009

By Edgar Peek

Lixiviant regeneration is by definition a precondition for any hydrometallurgical process. In chloride hydrometallurgy either HCl or Cl2 has to be regenerated in order to establish an economically viable metallurgical process. One such regeneration process is widely used with steel pickling where HC1 is regenerated through the thermal decomposition of ferrous chloride in either spray roasters or fluid bed pyrohydrolyzers. This standard HC1 regeneration process deserves to be considered as a potential separation process, since thermodynamic calculations show that a fluid bed pyrohydrolyzer can function as a ferrous-nonferrous separator. Several nonferrous,metals such as zinc, lead and cadmium can be volatilized as a chloride under ferrous chloride pyrohydrolysis conditions. If such a nonferrous metal volatilization could be achieved in the case of slurry feeding of "contaminated" iron oxides, then this would increase the Fe/H2O ratio of the (process) feed and thus save on fuel per ton of iron, while yielding a marketable iron oxide product. Previous test work on synthetic materials revealed that the near-complete separation of zinc, lead and cadmium from iron oxide was possible in a pyrohydrolytic atmosphere, even if zinc was present as zinc ferrite (more than 99.5%). This investigation, which was carried out in a tube furnace at 1100 K has now been extended to treat synthetic zinc minerals and also franklinite ore. For the latter, it was found that 85% zinc volatilization could be achieved in 4 hours at 1300 K. It is postulated that complete zinc volatilization could not be attained due to the formation and/or presence of gahnite and hardystonite, which might be stable in HCl/H2O atmospheres at 1100 K. The effect of adding small amounts of calcium chloride to react with gahnite and hardystonite to give zinc chloride and both calcium aluminates and silicates is being discussed. Test work on slurry feeding of this complex ore in a recently constructed 4-inch diameter fluid bed pilot unit has been planned for the near future.

Jan 1, 1995

By Joner Oliveira Alves

The aim of this work was to study the use of steelmaking slag as raw material to the production of rock wool and glass wool. Firstly, the chemical composition of the slag was analyzed. These results were used to infer the amount of additives to assemble the charge for the experiments. A laboratory-scale electric furnace was used to melt the mixtures used as charge. The melt material were turned into a water filled recipient, this process was performed in order to impose a fast freezing that is a characteristic of mineral wool production. Finally, with the rest of the melt material it was performed the Herty Viscosity Test. Samples of the produced material were characterized by different analyses. The results found in this research may lead to a technological innovation, because they indicate that the use of steelmaking slag to produce rock wool and glass wool is possible.

Jan 1, 2009

By Fanke Meng

Electrolyzing oxides of titanium, aluminum and niobium could prepare high-Nb bearing TiAl alloy (Ti-45Al-9Nb) at 1500°C. The chosen electrolysis voltage is 3.5V, which is lower than reducing voltage (~4.7V) of electrolyte CaF2, but higher than that of titanium, aluminum and niobium oxides. The investigation shows that compared with traditional methods, this method for preparing high-Nb bearing TiAl alloy is of many advantages such as few steps, friendly environment, low energy consumption, low cost and high current efficiency.

Jan 1, 2009