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By Mao Chen, Baojun Zhao, Zhixiang Cui, Leonel Contreras

Viscosity is one of the important physiochemical properties of metallurgical slags which is important for slag tapping, metal loss in slag, freeze lining and fluid dynamics. High temperature viscosity measurements are time- and cost-consuming and the number of experiments is limited. Viscosity model is an effective way to predict the viscosities of the complex slags at high temperature. However, a reliable viscosity model can only be developed on the base of accurate experimental data. A unique high-temperature viscosity measurement apparatus developed at The University of Queensland enabled accurate viscosity data to be measured for the “FeO”-SiO2-CaO-MgO-Al2O3 system in equilibrium with Fe. An accurate viscosity model has been developed based on Eyring’s theory and extensive viscosity measurements. The viscosities of copper smelting, converting and cleaning slags over a wide range of compositions and temperatures can be predicted and applied in the process control.

Jan 1, 2016

By Hadi Fanisalek

"Most industries attempted to conduct their energy consumptions in an optimized way for a few decades. This is because policymakers and top managements in industries have felt the critical situation of a possible energy shortage that could happen for them in the near future, even in countries with significant fossil fuel resources. Decisions related to energy consumption in any industry will have a long-term effect on different parts of the industry structure. In this way, energy decisions should be categorized as part of any industry's main strategic and long-term decisions, which should be made by top strategists. On the other hand, strategic management has many powerful tools to help the policymakers in industries to establish a long-term strategy for energy consumption and reducing or preferably eliminating the energy loss. This will be more important for industries in the Middle East, where they have just started to make an applicable strategy for their energy consumption and to design a long-term procedure for their energy management. Based on strategic management and by comparison we designed and offered a new model for establishing the main structure of energy management strategy in primary aluminum industry, which is a high consuming energy industry. This strategy, which we will call ESM (Energy Strategic Model) and has been applied for a typical primary aluminum industry in this paper, is similar to the practical models in the field of strategic management, which were developed for designing the overall company strategy.IntroductionThe elementary goal for introducing strategic management in any organization was to establish a successful plan helping the company to survive and to gain competitive advantage over its competitors in a rough business environment. Strategic management is an ongoing process that evaluates and controls the business and industries in which the company is involved; assesses its competitors and sets goals and strategies to meet all existing and potential competitors; and then reassesses each strategy annually to determine how it has been implemented and whether it has succeeded or needs replacement by a new strategy to meet changed circumstances, new technology, new competitors, and a new economic environment[!]."

Jan 1, 2013

By N. El-Kaddah, J. W. McKelliget

"A mathematical model for the analysis and design of hybrid plasma reactors for advanced materials synthesis is presented. The model is based upon a solution of the electromagnetic vector potential equation and is capable of predicting the two-dimensional velocity, temperature, and electromagnetic fields as well as the reaction kinetics inside the reactor for any axi-symmetric coil configuration. The model is used as a computer aided design tool for the design of hybrid plasma reactors consisting of a conventional DC torch augmented by an RF induction coil and it is demonstrated that the hybrid system possesses superior characteristics for materials synthesis over conventional DC or RF systems. The coupling between the RF and DC components is found to affect both the temperature field and the flow field and to have a significant effect on the reaction kinetics and on materials recovery. The model is used to study the thermal decomposition of silicon tetrachloride as a function of reactor design and operating parameters and it is demonstrated that through a CAD approach it is possible to significantly improve the operation of materials synthesis systems.IntroductionIn recent years there has been growing interest in the use of the inductively coupled plasma for chemical synthesis as a way of meeting the increasing demand for high quality, high performance materials for use in critical applications/l/. Although the basic feasibility of this approach has been demonstrated in the laboratory/2,3/ there still exists a number of operational problems that adversely affect system performance for some applications. In particular, the recirculation and back flow effects that arise from the electromagnetic forces in the plasma can result in the repulsion of the reactants from the hot plasma core and their subsequent deposition on the walls of the reactor. Another operational problem arises from the fact that the energy dissipated in the plasma has to compensate for the heat losses to the environment by conduction, convection, and radiation in order to maintain the ionization of the plasma and, hence, the stability of the plasma may be affected by the presence of the reactants and their products."

Jan 1, 1988

By Seshadri Seetharaman, Nurni N. Viswanathan, Haijuan Wang

"In order to make the stainless steel making process efficient and environment friendly, it is essential to minimize the loss of chromium to the slag phase. With a view to investigate the advantages of using CO2 to attain moderate oxygen partial pressures in the oxidant gas during the decarburizations of stainless steel, the present experiments were carried out to understand the oxidation kinetics of Fe-Cr alloys and Fe-V alloy with gas mixtures containing CO2. In the present work, the oxidation behavior of Fe-Cr and Fe-V was examined by thermogravimetric analysis (TGA). Various mixtures of O2 and CO2 were used as the oxidant gas and the oxidation rate was followed by the weight changes as a function of time.The experiments demonstrated that the oxidation rate is independent of temperature at present experimental situation, but has strongly related to the Cr-content of the alloy as well as the oxygen partial pressure in the oxidant gas mixture. The wetting of alumina by the iron drop and the change of the drop shape during the course of the oxidation were investigated by X-ray radiography."

Jan 1, 2010

By Dan Wang, Qian Xu, Guangshi Li, Xionggang Lu, Xingli Zou, Zhongfu Zhou, Hongwei Cheng, Changyuan Lu

The preoxidation of the ore has a profound significance to the concentration, separation and purification of nickel and copper from the lean complex ore. In this paper, the natural Ni-Cu sulfide mineral samples under the elevated temperature condition in air were investigated, as well as under isothermal condition at 600 oC in air. The mineralogical characterization was studied using XRF, ICP and the Rietveld method. The oxidation behavior and the element migration of the Ni-Cu sulfide ore were studied by XRD, SEM-EDS and TG. The XRD Rietveld method was successfully developed in the phase identification and quantification of this complex ore powder sample. The oxidative intermediates (Cu/Ni-ferrite) were detected by XRD, and the process of the element migration was obviously revealed by the line scans using SEM-EDS. It is the preoxidation of this mineral that provides guidance for the extraction of valuable metals from low-grade Ni-Cu sulfide ores in the future.

Jan 1, 2015

By Ana P. Paiva, Marc F. Comella, Sandra S. Reis, Joao N. Reis, M. Soledade Santos

"In this work, the influence of the malonamide structure, acidity of the aqueous phase and diluent on the equilibrium interfacial tension (IT) of N,N'-dimethyl-N,N'-diphenylmalonamide (DMDPHMA) and N,N'-dimethyl-N,N'-dicyclohexylmalonamide (DMDCHMA) in 1,2- dichloroethane (1,2-DCE), and DMDCHMA in toluene, with aqueous HCl, were investigated. IT isotherms were determined using the Du N ouy ring method. Densities of the organic phases were determined, and used to screen solute-diluent interactions. Formation of third phases was never observed; furthermore, ITs increase with the phase separation period, constant values being obtained for separation periods larger than 1000 seconds. Each malonamide interfacial efficiency at the oil/water interface is interpreted in terms of malonamide basicity, diluent polarity and malonamide - hydrochloric acid- diluent interfacial interactions.IntroductionFor several years now, N,N'-tetrasubstituted malonamide derivatives have been extensively investigated as liquid-liquid extraction agents since they were first proposed as the organic components of the DIAMEX process, with the aim of advantageously replacing tributylphosphate in PUREX [1]. Therefore, a significant part of research studies with malonamides appearing in the literature deal with the extraction of major and minor actinides in real or simulated spent nuclear fuels in nitric acid solutions [2]. Under typical experimental process conditions, the tendency shown by some N,N'-tetrasubstituted malonamide derivatives to aggregate in the organic phase, leading in a few cases to the formation of undesirable third phases, has been remarked and consequently thoroughly investigated [3, 4]. The increasing use of chloride streams as hydrometallurgical aqueous feeds is becoming a reality, and this fact is obviously deeply founded on an extensive research carried out to recover value-adding metals from these media. Following this trend, a number of N,N'-tetrasubstituted malonamides have already been screened for the recovery of iron(III) [5, 6] and platinum-group metals [7] from hydrochloric acid solutions. The results obtained are quite promising either in terms of total metal ion recoveries or selectivity patterns achieved. The formation of a third phase when iron(III) was extracted by the tested N,N'-tetrasubstituted malonamide derivatives has never been observed under the adopted experimental conditions, and the extraction data collected would need to be reinterpreted accordingly if any aggregation phenomena involving the considered extraction systems were to take place."

Jan 1, 2011

By Bin Xu, Qian Li, Ya-xuan Wang, Yong-bin Yang, Xi Zhang, Tao Jiang

The effects of common associated sulfide minerals including pyrite, arsenopyrite, galena and sphalerite on thiosulfate leaching of gold were studied in this work. Sulfide minerals had significant effects on gold leaching because that the dissolved products of sulfide minerals precipitated on gold surface to form coating layer. The degree of sulfide minerals impact on gold dissolution decreased in the order of pyrite ≈ galena > arsenopyrite > sphalerite, while the degree of effects on thiosulfate consumption decreased in the order of pyrite > arsenopyrite > sphalerite > galena. The additive CMC (Carboxymethyl cellulose) could not only reduce thiosulfate consumption but also increase gold dissolution. The mechanism of this might be that CMC could restrict the decomposition of thiosulfate by cupric ions and the precipitates on gold surface.

Jan 1, 2015

By Peter A. Spencer

The metallurgical parameters necessary for the design of a carmercial scale bio-oxidation plant have been determined for the treatment of a refractory arsenopyrite concentrate using a moderately thermophilic bacterial culture. The parameters considered were bio-oxidation rate, culture growth rate, nutrients, solids density, level of bio-oxidation, particle size distribution and oxygen uptake rate. The approach for obtaining the optimum values for these parameters is discussed and values based on results fran batch and continuous testing are given. Estimates of the capital and operating costs for a plant treating the carmercial arsenopyrite concentrate have been calculated fran the test data.

Jan 1, 1990

By Jie Ma, Bo Wang, Jieyu Zhang, Jian Zhao, Guangxin Wu, Shunli Zhao

"Nucleation and growth model based on a 3D CAFE model, which was incorporated with macro heat transfer calculation within ProCAST software was used to predict the solidification microstructure of austenitic stainless steel in twin-roll strip casting. The simulation results of solidification microstructure agreed well with experimental results of austenitic stainless steel. The effect of different casting process parameters on the solidification microstructure was simulated. The predicted results show that solidification microstructure is obviously sensitive to superheat and convection heat transfer coefficient. With the increase of superheat, the grain density decrease and the proportion of columnar crystal increase. In addition, the proportion of columnar grains increases when convection heat transfer coefficient increases. Thus, it was demonstrated that the solidification microstructure evolution of twin-roll strip casting could be predicted reasonably by using this model.IntroductionNear-net-shape casting technology is an important research area in the iron and steel industry today. Twin-roll strip casting represents a major area of concentration of near-net-shape casting technology. It has been widely used for its outstanding advantages, such as extended solubility of alloying elements, refined solidification microstructure and reduced microsegregation [1]. Furthermore, it is the most environmentally friendly, energy saving, and C02-sensitive way to produce steel strips [2]. Therefore, much attention remains to be paid to this aspect. A lot of published works indicated that the solidification microstructure of twin-roll thin strip has obvious effect on the thin strip properties [3, 4]. For the accurate control of parameters of the process are made difficult due to the complicated process and the multi-fold factors, great attentions have been paid to numerical simulations to provide insight into the solidification behaviors of the thin strip formed by twin-roll strip casting [5, 6].Simulations of casting solidification can provide a method to predict microstructure and to improving strip quality by controlling the process parameters."

Jan 1, 2014

By Tingyao Liu, Lihui Han, Qing Liu, Bao Wang, Teng Yang, Yong Sheng

This paper mainly investigates the mass transfer phenomena of rare-earth concentrate from leaching process in Rushton stirred tank reactor with rotate speed of 100-600 rpm. In the research, a certain amount of sphere particles with 50-450 μm in diameter is treated as the mineral particles. Comparison of laboratory experiment data with numerical simulation is performed. The results show that the critical impeller speed for complete dispersion is 300 rpm. And the maximum value of turbulence kinetic energy appeared 15 mm away from paddle, where the mixing time is decreased 55% and 80%, respectively, when mineral particles are injected into stirred tank through one or four filling ports. Moreover, with mixing process going on, the numbers of particles near the paddle region accounts for as much as 58% of the total amount. Meanwhile, following the particle diameter increasing, the particle concentration of the upper part of stirred tank reactor is increased.

Jan 1, 2015

By Carlos G. Levi

"The principles involved in the rapid solidification of supercooled metal droplets and existing numerical models are reviewed. The limitations of these models for studying alloy solidification are discussed in terms of the effects of alloying elements on the relevant heat transfer, thermodynamic and kinetic parameters. Analysis of the enthalpy-temperature diagram reveals how the extent of rapid solidification is hindered by the addition of solute. A solidification model incorporating thermodynamic and kinetic relationships into a Newtonian heat transfer formulation is used to analyze the thermal history and concurrent solute redistribution during recalescence. IntroductionIt is well acknowledged that microstructural evolution during solidification is intimately associated with the thermal history of the liquid-solid interface. Structural parameters like chemical homogeneity, morphology and size scale of the phases can be related to the interfacial temperature and velocity. These in turn change by the interaction of the interface with the thermal and solutal fields in its neighboring environment.The thermal history of powder solidification can be conveniently described on the enthalpy-temperature diagram for a pure metal shown in Figure 1 and discussed in detail elsewhere [1). A system can conceivably follow any path of decreasing enthalpy in the supercooled region of Figure 1 (~ < 1), starting at the nucleation temperature (oN < 0) on the liquid line, and ending at some point on the solid line. A vertical path represents an isothermal transformation, of which a limiting case is solidification without significant barriers to nucleation and growth, with the interface at the equilibrium temperature TM (path one in Figure 1). A horizontal path represents isenthalpic (or adiabatic) solidification whereby the system could form an amount of solid proportional to the initial supercooling of the liquid without further heat loss to the environment. A liquid that can completely transform to solid under adiabatic conditions is said to be ""hypercooled""."

Jan 1, 1986

By Renato G. Bautista

"The development of processing methods for the preparation .of three electronic materials with rare-earth components is discussed. The resulting processing innovations are the results of a search for an economically competitive pilot scale or industrial production flowsheet without compromising the required properties of the final products. The three cases highlighted in this presentation are: 1) The preparation of high energy (Pr-Nd-Ce)FeB magnets for MRI application from a mixed-rare-earth oxide with a narrow range of composition directly prepared from the solvent extraction circuit of bastnaesite ore. 2) The kg production of the giant magnetocaloric effect Gds(SixGe1-x)4 magnetic refrigerant materials from commercial grade gadolinium metal (95 to 98 at. % pure) instead of high purity gadolinium metal (99.8 at. %); and 3). An industrial chemical synthesis flowsheet for the production of the superconductor precursor of YBa2Cu3O7.INTRODUCTIONIn the laboratory discovery stage, the synthesis of a new material is carried out using very high purity components, usually the highest purity available. As the new material is studied and characterized, the effectiveness of its desirable properties becomes better defined and understood. The evaluation of the effectiveness of the .property over the range of a given parameter and other interactions are further studied. Once it's potential application becomes clear, a practical and economical processing method need to be developed. The successful material processing flow sheet does not necessarily have to be a scale up of the laboratory procedure. At this stage, substitution of starting components and with lower purity materials is considered as the economics of the processing becomes a major issue. In addition, other approach to it's synthesis"

Jan 1, 2000

By R. S. Krarner

Fly ash, a by-product of coal burning power plants, poses a major problem for the utility industry since most fly ash must be landfilled. These quantities may represent as much as 20% of the total material going into landfills. A major problem with fly ash utilization is that although the ash consists of useable components, ash composition can vary depending on the types of coal burned and plant operating conditions. Ash is first characterized using SEM, image analysis, and chemical methods. Processing techniques were developed to separate ash into various components including cenospheres, magnetic spheres, carbon, and clean ash. These products are again evaluated for various utilizations before being used to produce valuable products such as mullite, activated carbon, fillers in plastics, and concrete.

Jan 1, 1994

By J. J. Moore

The application of plasma technology to process metallurgy is briefly discussed. Experiments involving in-flight reduction of minerals (taconite, chromite, in particular) with a solid-based carbon reductant are described. The resultant metallic and slag product analysis is discussed with respect to thermodynamic and kinetic considerations.

Jan 1, 1985

By Sridhar Seetharuman

Sulfur and oxygen dissolved in nickel and cupronickel melts can be removed as gaseous oxides of sulfur by a vacuum treatment. Presented in this paper is a new matched thermochemical diagram that permits direct evaluation of the equilibrium partial pressure of SO, as a function of temperature over an alloy of specified composition. The matched thermochemical diagram consists of a central plot which shows the integral Gibbs&apos; energy of mixing for the binary system S-O2, at different temperatures. The central plot is flanked on either side by terminal plots of the chemical potentials of oxygen and sulfur, as functions of temperature, for different alloy compositions. By projecting the chemical potentials of oxygen and sulfur from the terminal plots on to the central diagram, the equilibrium pressure of SO2,can be directly read on the nomograms on the central plot at different temperatures. The matched thermochemical diaerams are - useful in assuring the efficiency of vacuum refining.

Jan 1, 1993

By Suman Das, Justin J. Gambone, Rohan Bansal, Ranadip Acharya, Paul Cilino

"This paper focuses on generating a quantitative microstructure prediction model for Scanning Laser Epitaxy (SLE) process based on coupled flow-thermal modeling using Finite Volume method. SLE is a laser-based additive manufacturing process for the deposition of equiaxed, directionally solidified and single-crystal nickel superalloys through the melting of alloy powders onto superalloy substrates. In the current work, the detailed effects of natural and Marangoni convection on the flow field are studied and the results are analyzed in terms of the temperature gradient, vorticity parameter, melt pool dimensions and mushy region extent. The detailed property data of the processed superalloy and the laser scan path are incorporated in the model to predict the microstructure in realistic scenario. An optimization study is carried out to evaluate the critical parameter values at which the columnar-to-equiaxed and the oriented-tomisoriented transition take place. This work is sponsored by the Office of Naval Research through grant N00014-11-1-0670.IntroductionSLE is a laser-based additive manufacturing process for the creation of structures in equiaxed, directionally solidified and single-crystal nickel superalloys through the selective melting and resolidification of superalloy powders. In SLE, a tightly focused laser beam is guided by a highspeed galvanometer scanners allowing for tight control of the amount of energy being applied to the top of the powder bed, as well as the speed at which the melt pool moves across the substrate. Under the proper operating conditions and with sufficient substrate meltback, the solidification microstructure follows the morphology of the underlying substrate, allowing for directional and even SX growth.Several reports on the modeling aspects of laser cladding-based additive manufacturing approaches can be found in the literature. Approaches based on Finite Element Methods (FEM) and Finite Volume Methods (FVM) are employed for the thermal modeling of the system [1, 2]. Gaumann coupled the Columnar to Equiaxed Transition (CET) modeling with the Rosenthal solution in earlier work based on laser cladding [3]. Rappaz et. al. provided a detailed modeling of the microstructure/columnar orientation based on the solidification velocity and crystalline orientation [4]. This approach is based on the selection of the growth direction that closely follows the melt pool normal direction. Later on, substrate orientation is also taken into account [5, 6]."

Jan 1, 2013

By Marcela Morvová, Mário Janda, Morva Imrich

"The possibilities of greenhouse gas mitigation using various methods are brought out. The special case of utilization of mixture of CO2 with other greenhouse gases in a synergetic way inside non-thermal plasma based system is described in detail.Measurements on pilot system comprising pyrolysis chamber as alternative energy system (production of hydrogen and liquid tar) were made for various biomass and waste as the input material. The exhaust from this system was treated with non-thermal plasma gap suitable for up to 650Nm3/hour of exhaust gas flow. Condensable portion of exhaust is liquefied in distillation unit; produced hydrogen is stored on-line inside nano sized carbon of our own production.The CO2 removal efficiency varies depending on exhaust composition between 45 to 98%. Other oxides as CO, NOx, SOx and several hydrocarbons and VOC are also removed. The main product connected with CO2 removal is a solid powder of proteinoid nature. There exist strong probability, that precursor of the origin of life on the Earth from primary atmosphere were formed in the similar way as it is present in the electric discharge system used. Our system is equipped with on-line as well as ex-post analysis of all forms of products. We have also developed a system for recuperation of all forms of produced heat. It is stored inside as latent heat of waxes.IntroductionNatural greenhouse effect on the Earth is caused mainly by water vapour with the average absolute concentration about 4%. Other gases able to absorb long-wave radiation and thus this causing greenhouse effect are CO2, CH4, N2O, halocarbons and as precursors ozone and NOX. Some of them we produce and introduce into atmosphere in large quantities during production of energy and in transport. This factor leads to permanent increase of average temperature of air, sea and oceans, so called global warming.Nowadays large amount of data exists showing that the temperature of Earth in the last 150 years has been continually increasing. It represents about 03°C per ten years and the most of climatologist believe, that the increased concentration of greenhouse gases in the atmosphere is responsible for this effect.The most important greenhouse gas is carbon dioxide CO2. Majority of CO2 emissions comes from electric power stations working with fossil fuels, cars and industry. Burning of fossil fuels contribute up to 80% to world wide anthropogenetic emissions of CO2."

Jan 1, 2010

By J. Shibata

The recovery process of valuable metals, such as Ll, Mn, Ni and Cr from a waste lithium battery was developed n this study. Lithium and Mn are selectively leached from the battery by using dilute mineral acid. Main part of the battery comprises stainless steel, and Fe, Ni and Cr are easily leached by the mixture of dilute HCl and HNO3 Lithium and Mn are precipitated as metal carbonates from the? individual leached solution with sodium carbonate solution. The solution containing Fe,Ni and Cr Is treated by solvent extraction to separate NI and Cr from the leached solution. The experiments are carried out for leaching and separation steps. According to the experimental results, the flow. sheet for a recovery process of valuable metals from a waste lithium battery has been established.

Jan 1, 1995

By Toshiyuki Hiranami, Keizou Uematsu

"AbstractionSpray freeze drying method was proposed to fabricate ·ceramic: powder granules for high performance ceramics. Obtained granules and their green compact were characterized by SEM and immersion liquid technique. Granules have a spherical shape of about l 00 µ m in diameter, ·and no binder segregation was found with the immersion liquid technique. The granule had sufficient strength for usual handling, while the strength was much lower than that of granules prepared by conventional spray-drying. Unlike the conventional green compacts, granule interfaces were not observed in the green body made with the spray-freeze dried granules.IntroductionIt was well kn9wn that spray-dried granules have binder segregation layer on their surfaces. The trace of this segregation layer survives in the later processes i.e. compaction and firing, and behaves as fracture origins in the sintered bodies. The origin of this problem is solvent drying process from slurry droplet surface in spray drying system. As alternative method we propose a freeze drying process for granule preparation, in which solvent is remove by sublimation though the process, binder segregation can be prevent.In this study, we applied spray freeze drying method to fabricate alumina powder granule, and characterized the obtained granules, and their green compacts and sintered bodies.Experimental procedure.Alumina powders and additives aqueous solution were mixed for 24 hours using a ball mill to· prepare the slurry for spray freeze drying. .The solid loading of the slurry was 30vo1%. Deflocculant (PAA-NH4 type) was added 0.5mass%, and the binder (PVA). 1.0, 2.0 or 3.0mass% of alumina. Obtained slurries were sprayed into liquid nitrogen to make frozen granules. The granules were freeze dried.For the characterization of the granules, immersion, liquid technique observation and single granule strength test were carried out. Strength of individual granule wa5 measured using micro compression testing machine (MCTM, SHIMADZU). Granule strength was calculated from following equation."

Jan 1, 2000

By R. Vasant Kumar

Measurement and control of trace elements in molten metal are often critical in order to achieve optimum production, refining, alloying or recycling. Solid electrolyte sensors for monitoring oxygen and very recently for hydrogen have made major impact in the metal industry. It has not proved straightforward to develop solid electrolyte sensors for many other elements that can be industrially applied in metal production. Novel self-tuning chemical sensors have been developed by the authors that may open up new technological opportunities. Three such examples will be presented in this paper: (i) a self-selecting oxygen-sulfur dual sensor using a composite beta-alumina/zirconia solid electrolyte; (ii) a copper sensor for liquid matte based upon cusicon solid electrolyte operating in a current reversal mode; and (iii) an aluminium sensor on solid NaCl containing channels of molten NaAlCl4 electrolyte formed by electrochemical charging in molten zinc.

Jan 1, 2006