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By H. Castillo

This paper describes the computer simulation of thermal stress fields generated in the quenching of the ns 415 H Steel automotive parts (Valve Lifters), running the ANSYS Multiphysics software of finite element (FEM). Simulation was performed introducing residual stress measurements on specific values areas, like internal pressure condition in the material. The stress condition effect in the material and the properties as temperature function data, were introduced to the FEM software. The thermal stress simulation was made on the 2D system. The parts were austenized to 850 900 °C and then oil quenched, tempered at 150 -200°C, and air cooled. The X-Ray diffraction technique was made to take measurements from residual stresses on valve lifters surfaces. The results analysis showed the ideal stress condition necessary in raw material to reduce the scrap percent in grind operations after hardening heat treating process. Keywords: Thermal Stresses, Temperature profile, Computer Simulation, Finite element analysis, Quenching of steel, Residual Stresses

Jan 1, 2003

By Onuralp Yiicel, Ozlem Okur, Murat Alkan

"In this study, Co-Cr-Mo alloys were produced using a mixture of Co304, Cr203 and Mo03 powders with Al powders by a Self-propagating high temperature synthesis process. SHS is a process of material synthesis that has revealed a number of reactants combinations capable of much higher energy release than conventional explosives. Al203 is added to the mixture to decrease the adiabatic temperature of the system. The thermodynamic simulations and the calculations of adiabatic temperature were examined with FactSage 6.2. In the SHS experiments, different Co304/ Cr203/Mo03 ratios were examined, and their effects on the metal recovery and alloy compositions were carried out. The samples were characterized by using chemical analysis, XRD, XRF and SEM/EDS techniques.IntroductionSelf Propagating High Temperature Synthesis (SHS) has significant advantages compared to the high technology furnace applications, such as very short processing time, simple operation, low energy requirement and low cost [l, 2]. In a SHS process, the ignition starts the combustion and propagates throughout the reactant mixture yielding the desired product. However, the disadvantages of the process such as inhomogeneous or unreacted products due to undesirable reaction rates needs to be overcome by changing some parameters such as ignition temperature, particle size, additive, atmosphere etc. [3, 4]. This work aims to establish a scientific and engineering background in the production of some cast Co-Cr-Mo master alloys via SHS (Self Propagating High Temperature Synthesis) metallurgy which is attractive process technique regarding fast and low-cost production ability of cast alloys."

Jan 1, 2013

By R. T. Seaman

Pressure oxidative treatment of whole ores and/or mineral concentrates is used to leach or liberate metals of value for downstream recovery. Silver, when present, is often lost in processing, precipitating as a cyanide-insoluble jarosite in the residue. Depending on pressure oxidation conditions, the degree of silver loss to jarosite can vary dramatically. Batch bench-scale testwork is often performed to define that loss, and then assess the implications in continuous operations. This paper focusses specifically on the impact of CESL pressure oxidation conditions on silver recovery, and discusses limitations of batch bench-scale testing as well as means of overcoming these limitations to better predict silver recovery in the scale up from bench-scale to continuous operations. Since silver is only partially soluble in both sulphate and chloride media, it will gradually leach and deport to a jarosite as oxidation progresses. When a silver-insoluble anion, for example iodide, is dosed prior to oxidation, there is a marked improvement in silver recovery from batchgenerated residue; however, that benefit is not consistently seen in continuous operations. The difference has been attributed to the dynamic solution conditions in the batch test, specifically the first few moments of oxidation. Using these principles, a predictive correlation has been established between initial leach concentrations of iron and acid and ultimate silver recovery with iodide addition.

By Yong Li, Tao Jiang, Xiangxin Xue, He Yang

"In this paper, we describe the current status and research progress on the utilization of typical industrial solid wastes in China. We propose a creative method called “eco-utilizing wastes” with an aim of both integration and increment but without second-time waste and pollution, in terms of the characteristics of typical industrial solid wastes, such as titanium-bearing blast furnace slag, high-silicon iron tailing and boron-enriched slag as well as oil shale.Situation of Typical Industrial Solid Wastes in ChinaThough mineral resources in China are abundant, most of these are low grade ores. Moreover, the distribution of mineral resources is asymmetric, which causes the increase of cost and decrease of the economic benefit. Over-exploitation of mineral resources results in a large number of solid wastes. The accumulation of solid wastes not only means the waste of valuable resources, but also causes environment deterioration. There exist some problems in the current practice of the disposal of industrial solid waste, such as only emphasizing the final results and causing new pollution and waste [1]. So the research and development of a high value-added method has a high practical relevance to our nation. Based on the present status and research progress of industrial solid wastes in China, a creative new idea and method for eco-utilization of solid wastes is proposed in this paper."

Jan 1, 2012

By Neale R. Neelameggham

"Most chemical process plants and metallurgical production facilities have some sort of cogeneration to minimize process energy costs. Use of Alternative Energy Production from sun and wind power with storage can become an integral part of a process plant utility. This will facilitate reduced fossil fuel usage and help minimize thermal emissions. This will be similar to Pollution Control equipment, which have become an essential part of process plants in the past four decades. Conceptual flow sheets of such Process Utility schemes are presented.IntroductionPower is supplied to industries, commercial and residential users. Over the past decade, Electric Utility companies have made major inroads, in introducing alternative energy resources in an attempt to somewhat reduce fossil fuel use in power generation. Now, on a much larger scale than in the early 1980s, residential users, motivated by government provided tax credits, have started installing alternative energy generators such as roof top wind mills or roof-top photovoltaic generators. This will minimize future energy costs, help control thermal emissions etc. This alternative power generation is typically connected to the existing power grid with two way power metering. However, the use of alternative energy generation has not been seen at large industrial sites yet.Paul Scherer Institute, Switzerland and the NREL laboratories in Colorado, are two of the several institutes which have been developing how solar thermal power can be used to supply the endothermic input energy in chemical and metallurgical processes. The theme of this present symposium addresses the above as well as the energy storage needs for such events to become continuous. This paper emphasizes the concept of how alternate energy can be used in the production of materials on a generic sense wherever there is a need for input energy – beyond endothermic process energy - while addressing how to reduce the thermal and carbon emissions.The alternative energy generation using wind or solar source is discontinuous due to the nature of the energy source. They are not only discontinuous but also variable. This necessitates storage of generated power for close to continuous use with variable loads. C Smith, et al pointed out in 2006, that 'the electric power industry has taken notice of the expansion of wind and its potential' in a summary article on integrating wind generation into utility systems.1 In 2009, the 1000 MW wind generation project in Texas had to be postponed to 2013 for lack of transmission.2 There are only a few large MW solar generation units in the US; the projects being slow mainly from lack of adequate storage and redistribution."

Jan 1, 2010

By P. G. Comba

Many gold producing states are requiring rinsing of spent heaps to render the leached ore compatible with the environment and are placing restrictions on effluent pa, cyanide, and metals concentrations. Parameters which may affect efficient rinsing of heaps have been investigated by the U.S. Bureau of Mines in laboratory column studies. Rinse profiles for cyanide, metals, and pH as a function of the volume of water passed through the spent ore are presented. Fresh water rinsing of spent ore in columns showed that rinsing of cyanide was not affected by the rinse solution application rate. Interrupted rinsing with a rest period between applications reduced the volume of water required to meet effluent cyanide concentrations. chemical oxidation of the effluent with recycle of the rinse solutions reduced effluent cyanide concentrations and the volume of waste solution generated. Water rinsing was not successful in reducing the alkalinity of the cement agglomerated ore. A dilute acid solution had to be applied after cyanide removal to reduce effluent pa levels to specified limits.

Jan 1, 1992

By Orlando C. Rojas

The Potrerillos Smelter commissioned a new El Teniente converter in 1985. As a result of the use of this technology, the Peirce-Smith converters have been processing only high grade matte or white metal. These operational changes resulted in damages to the converter shells, excessive splashing and cold dope generation and very short refractory campaigns. The paper shows the modifications to the tuyere angle, mouth design changes and new techniques for mouth cleaning and gas handling. Operational results up to 1991 are also shown.

Jan 1, 1993

By I. Hilerio

Chromium Nitride (CrN) thin films were deposited on AISI steel 316 substrates by means of the reactive magnetron sputtering method. CrN films were produced under two different conditions. In the first one, the substrate was heated by a DC source. For the second coating a negative substrate bias voltage was applied. X ray diffraction, quantitative energy dispersion and scanning electron microscope were employed to characterize the two different phases, their chemical composition as well as their microstructure. In addition, a microhardness test was carried out. The results show that a better phase formation of CrN thin films was achieved when a heating source was present (first case). Both coatings presented homogeneous surface. Their compositions show differences even when the gases flowing are the same in composition. Regarding to the hardness test results, there can be found a higher value when using a heating source.

Jan 1, 2009

By Sevinc Yildirim, Cigdem Oruclus

"Metal-Porous Silicon (PS) based structures dipped in water show the direct hydrogen fuel cell behavior. The effect of the thickness of the cupper (Cu) film on the electrical properties of direct hydrogen fuel cell is studied by fabricating Cu/Porous Silicon/n-Silicon/Indium structures. PS samples were produced electrochemical etching of n-type single crystalline silicon with a resistivity of 1,25 Ocm and (111) orientation. The thin films of Cu with different thickness between 200 and 600 nm were deposited on PS surface by electron-beam technique. Investigation of the effect of Cu layer on the performance of the structure indicates that the performance parameters such as open circuit voltage (Voc) and short circuit current (Isc) strongly depend on the Cu layer thickness. It was observed that the divice with an 350 nm Cu layer exhibits the highest open circuit voltage (0,5 V), short circuit current (0,01 mA) and power density (10 W.m-2).IntroductionHydrogen is the most attractive and ultimate candidate for a future fuel and an energy carrier. Hydrogen is recognized as the environmentally desirable clean fuel of the future since it can be used directly in different types of hydrogen fuel cells [1]. In the past years, the rise in portable electronics requires the development of miniature fuel cells compatible with standard silicon micro fabrication technology. Most silicon micro-fuel cells have used the polyperfluo-rosulfonic acid membranes (Nafion R) as a proton exchange membranes (PEM) that is not really integrated with standard micro fabrication techniques [2-5]. The composite materials such as inorganicorganic hybrid materials (Nafion-silica, Nafion-borosiloxane etc) are next generation of proton conducting membrane [4-8]. But, fuel cells run on pure hydrogen gas, which can be produced with other energy resources. Hydrogen smallest atom and thus the H2 gas can leak easiliy. The application of hydrogen for power sources has been greatly restrained due to the lack of safe and convenient generation and storage methods.A kind of hydrogen fuel cells Metal-PS-Si structures used as an energy water directly. There is no need pure hydrogen. Cu-PS-Si Schottky-type fuel cells with as proton-conducting membrane and the thin-film cupper catalist and water as fuel, which are interesting for fabrication of lowcost miniature fuel cells. Generation of the open-circuit voltage and short-circuit current has been observed by Cu-PS-Si structure dipping in different hydrogen-containing solution."

Jan 1, 2014

By Feng Liu

A thermal upgrading process by which nickel value can be concentrated in a ferronickel alloy is a possible alternative to treat Sudbury pyrrhotite (Po) tailings with nickel content of 0.5–1.5 wt%. The basis of this process is precipitation of Ni from Po at high temperature once Fe/S ratio in the iron-deficient Po is shifted towards stoichiometric or near stoichiometric FeS (troilite) either by the addition of iron and/or the removal of sulfur. For the iron addition route, the reaction between elemental iron and nickeliferous pyrrhotite to produce ferronickel alloy and Ni-depleted iron sulfide phase plays a critical rule. In this paper, the formation mechanism of ferronickel alloy was investigated using the diffusion couple technique to better understand the nickel diffusion behavior in the iron and sulfide phases.

By Xun An

Slag from an electric slag cleaning furnace was injected with methane and air mixtures to facilitate the recovery of copper and cobalt. The effects of methane-to-air ratio, gas flow rate and temperature on the reduction and metal separation were investigated. The results showed that over 90 percent copper and up to 60 percent cobalt could be recovered from the slag with a gas utilisation of around 70 percent, as calculated by thermodynamic simulation. Methane-to- air ratio was a major factor affecting the rate of reduction under the present experimental conditions. Further, injection of gaseous reductants greatly enhanced the coalescence and settling of entrained metal droplets. A reduction mechanism is proposed and the factors influencing the coalescence of copper droplets are discussed.

Jan 1, 1998

By G. Glinski, K. A. Pericleous

"Recent advances in new computational modelling techniques such as Lattice-Boltzmann and Dissipative Particle methods offer the prospect of simulating complex fluids such as colloidal and dense suspensions in industrial processes. They are referred to as mesoscopic methods since they lie between molecular dynamics at a microscopic atomistic scale «lO-9m) and traditional macroscopic CFD methods (> 1O-2m). The models behave like a 'coarse-grained' gas consisting of fictitious interacting particles, which are much larger than the real molecules of the actual fluid they represent. Inter-particle forces are set so that the collisions collectively mimic the phenomenological transport properties and flow of the underlying fluid at a macroscopic scale.Much of the developmental work to date has focused on laying theoretical foundations based on thermodynamic and kinetic theory. Successful applications include predictions of macroscopic transport properties of complex fluids and flows in porous media and filters. With the constant increase in computational power, these mesoscopic methods are now sufficiently developed to determine their suitability to simulate complex fluid flows in real industrial processes. This work describes the application of meso scopic methods to the stencil printing of solder pastes in the assembly of electronic components. The aim of this work is to assess the ability of these methods to study the transport mechanisms of individual solder particles suspended in the flux solvent as they enter and fill the micro-apertures of a stencil. This paper demonstrates the coupling of such mesoscopic methods to continuum CFD methods to predict the flow of dense suspensions (i.e. solder paste) in industrial processes."

Jan 1, 2001

By D. Donald Downey

Pilot Testing Ion Exchange Resin (IEX) can go from very simple beaker testing to complicated column testing. Space velocities, regenerant quantities, loading capacities, ion leakage, are all terms that get accumulated together to prove or disprove a resin’s (or resins’) ability to load a single ion (or specific set of ions). Not getting all the resin’s operating parameters correct will disqualify (or at least skew) the results. Laboratory tests for capacity, moisture content, bead size, metals fouling, etc.—what does it all mean? At last count, there were over twenty-five separate ion exchange resin tests (analyses) that were available to end users. Standard testing procedures identify the resin properties but more specific procedures can be used to identify problems with equipment operation. Then, there are the costs to consider; simple cation resin testing (moisture content, total capacity and bead integrity) is in the $200/sample range. However, add to this Chatillon, Russian Ball Mill Test, HIAC particle size, metals and % regeneration test procedures and the lab work can increase to over $1000/sample. In this paper, the author will explain the “must-do” pilot and test procedures and why they are important and the key to understanding how resin performs ion exchange.

By Musa Karakus

Ceramic build-ups are synthetic mineral deposits formed in critical locations in or near the throats of inductor units in channel induction furnaces, the preferred melting and holding furnaces used in iron foundries. The build-ups are undesirable because they slow down melt circulation, increase power consumption and cost. and decrease the quality of the metal. This study involved the determination of the mineralogy of build-up samples and the quantitative measurement of phase abundance in those build-ups by cathodoluminescence microscopy. These undesirable deposits usually are hard and dense and contain variable amounts of entrained metallic iron. The non-metallic phases dominantly consist of oxides and silicates of several refractory elements, AI, Mg. Ca, Si, and Fe. Minor amounts of the sulfides of Ca. Mg, Fe and REE elements, especially Ce and La. and the oxides and silicates of Ce and La elements are locally present in the build-ups. The build-up samples were found to be ideally suited for study by cathodoluminescence, which has provided an easy means for rapid re-cognition of the phases present in the build-ups. The phase compositions were determined by electron microprobe analysis. The phases identified and their characteristic cathodoluminescence shown in the ceramic build-up samples were: spinel (bright green, blue-green, and red). forsterite (red and purple), periclase (dark reddish-brown, blue. and orange), corundum (red, blue, orange, and white), anorthite (yellow, yellow-green, blue, and blue-purple), hibonite or calcium hexaluminate (dark green), mullite (dull red-brown), gehlenite (deep blue), silica(dark brown, pink, purple, red. and blue), monticellite (light violet blue and light pale yellow-orange), silicon carbide (orange), oldhamite (bright yellow and orange). Ce-La silicate phases (purple), and glass (orange, dull red, and purple). Non-luminescent phases were: hercynite, Fe-oxides, Ce-La-oxides, Fe-sulfides, and metallic iron.

Jan 1, 1989

By A. Bilodeau

A new hydrometallurgical process for the production of refined gold and the recovery of palladium and platinum from silver anode slimes has recently been developed and installed at the, CCR Division of Noranda Inc. The process, which facilitates the production of gold of >99.99% purity in the face of increasing palladium receipts comprises; leaching silver anode slimes with hydrochloric acid and hydrogen peroxide at 95°C to solubilize gold, palladium, platinum and base metals while simultaneously rejecting silver as insoluble silver chloride; precipitating gold from the leach solu¬tion with sulphur dioxide gas in two stages to produce a first-stage high purity gold product and a second stage impure gold which is recycled to the leach; washing, melting and casting of the pure gold; precipitation of a palladium-platinum concentrate from the gold-free solution by reduction with sodium formate at pH 4 and 95°C; and neutralization of the palladium precipitation effluent to pH 10 with lime. The results of laboratory and pilot plant studies leading to the adop¬tion of this process are discussed, and data are presented for each of the unit operations. Details of the engineering of the commercial plant are given, and plant start-up experience is described.

Jan 1, 1987

By Fumitaka Tsukihashi

Phase diagrams of the CaO-SiO2-FeOx-MgO, Al2O3 systems are necessary for the analysis of copper smelting reactions and sintering process of iron ore. The effect of MgO and Al2O3 addition on the liquidus of the phase diagram of the CaO-SiO2-FeOx system at low oxygen partial pressure was observed. The liquid phase area changed by the addition of MgO and Al2O3 with a changing oxygen partial pressure from 10-8 to 10-3 atm (10-1 to 102 Pa) at 1573K. The effect of Fe3+/Fe2+ ratio on the melting mechanism is discussed.

Jan 1, 2003

By Godwin J. Igwe

For soil remediation technology to be effective, a thorough understanding of the interactions between a targeted contaminant and the soil matrix is crucial. Proper selection of remediation technology, based on understanding the bonding/binding characteristics of the soil and contaminant, can often result in significant remediation cost savings. Contaminated soil cleanup is complicated by both the physical nature of the soil formation and the behavior of contaminants introduced into the formation. Contaminants can exist in the subsurface in different phase attached to the soil surfaces, dissolved in the ground water, or occupying pore spaces as a separate gaseous or liquid phase. Contaminants properties and how they exist in the subsurface influence their toxicity, mobility and treatability with different remediation technologies A soil characterization study was performed to provide information for remediation technology selection for an inorganic lead contaminated soil. The soil pH, TCLP analysis, thermogravimetric analysis, the soluble anions and cations present, equilibrium leaching tests, analysis by x-ray fluorescence, sequential extractions and speciation analysis using scanning electron microscopy, were all used. Results provided many insights into contaminant behavior in the soil, indicating ultimately whether soil washing or solidification/ stabilization remediation technologies were applicable.

Jan 1, 1994

By D. F. Suarez

Spontaneous nodulation leading to growth of well developed glossy spheroids (generally hemispheres) of up to 0.06 cm width in 120 min has been observed during copper electrodeposition with certain levels of glue, thiourea and C1-. Thiourea alone can produce spontaneous nodulation but addition of glue and/or Cl- is required for rapid and sustained growth. In most cases once the glossy nodules develop they consume the majority of the copper deposited; thus, the specific current densities (and hence copper electrodeposition rates) on the glossy nodules are about an order of magnitude or, more greater than on the adjacent planar surfaces. The texture of the adjaoent planar surfaces is not glossy in appearance but is well faceted showing the usual deposition grain structure for such additives. Cathode potentials when spontaneous nodulation occurs are about TOO my more negative than with usual copper electroplating. This fact associated with evidence of extremely high levels of cathode surface passivation based on cyclic voltammograms indicates that the conditions which lead to spontaneous nodulation result from a very tightly adsorbed additive surface film. This film breaks down in specific points initiating the glossy nodules which then grow at extremely rapid rates. Current density is also important in spontaneous nodulation. At equal deposition times a current density of 21.5 mA/cm produced much larger glossy nodules than at 48 mA/cm2. The surface concentration of the glossy nodules was much greater in the latter case, however. The role of current density is still not well understood. The role of it as well as the relative roles of the three additives, thiourea, glue and Cl- in spontaneous nodulation is presented. Preliminary results and some possible correlations of these to help explain spontaneous nodulation are presented. It is believed that tankhouse upsets where cathode nodulation occurs may be related to this phenomenon.

Jan 1, 1987

By A. M. Strachan

The application of submerged electric arc furnace smelting techniques to tin concentrates at the Capper Pass tin smelter in England is discussed. Some experimental data from earlier small scale 50 KVA electric smelting testwork on various low and medium grade tin concentrates is presented. Design considerations for the construction of a 3 MVA electric furnace to treat tin concentrates from the East Kemptville mine in Canada are considered, together with necessary precautions peculiar to the construction of a high grade smelter in close proximity to an existing low grade, complex non-ferrous metal smelting operation<. Slag composition modifications to optimise operational smelting conditions for various concentrates treated are discussed, together with refractory selection. The effect of concentrate impurity levels on the permissible degree of recycle to produce a satisfactory metal product is highlighted.

Jan 1, 1990

By Mark William Kennedy

Modern metallurgical plants typically have complex flowsheets and operate on a continuous basis. Real time interactions within such processes can be complex and the impacts of streams such as recycles on process efficiency and stability can be highly unexpected prior to actual operation. Current desktop computing power, combined with state-of-the-art flowsheet simulation software like Metsim, allow for thorough analysis of designs to explore the interaction between operating rate, heat and mass balances and in particular the potential negative impact of recycles. Using plant information systems, it is possible to combine real plant data with simple steady state models, using dynamic data exchange links to allow for near real time de-bottlenecking of operations. Accurate analytical results can also be combined with detailed unit operations models to allow for feed-forward model-based-control. This paper will explore some examples of the application of Metsim to real world engineering and plant operational issues.

Jan 1, 2014