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By David R. Jessey

An ore microscopic and geochemical study of the nickel-cobalt occurrence in the Southeast Missouri Mining District has revealed several significant relationships. Siegenite [(Ni,Co)3S4] is the dominant nickel-cobalt sulfide in the ores, however, several other members of the thiospi¬nel group (AB2S4) occur: carrollite (CuCo2S4), nickelean carrollite [(Co,Ni,Cu)3S4], fletcherite [Cu(Ni,Co)2S4] and polydymite (Ni 3S4). In addition, bravoite [(Ni,Fe)S2], vaesite (NiS2), millerite (NiS) and gersdorffite (NiAsS) are present. Thiospinel composition varies dramatically within the district. Paragenetic studies have shown that the stratigraphically lowest thiospinels are the most cobalt-copper-rich. A detailed ore microscopic study of the AMAX Lead Company Buick mine has also shown significant changes in mineralogical association, texture and grain size of the siegenite along the north-south strike of the major ore bodies. Siegenite commonly replaces and veins chalcopyrite and is subsequently replaced by sphalerite. Less commonly, siegenite and chalcopyrite are observed to form linear replacements along sphalerite grain boundaries. The grain size of the siegenite varies markedly, but in a predictable north-south pattern that is consistent with a genetic model formulated from geo-chemical data. The compositional as well as textural trends displayed by the thiospinel mineralization could be exploited to optimize recovery of any or all thiospinels of economic interest.

Jan 1, 1981

By Guo Xian Jian

In this paper, the gas composition calculations on the FeS-H20 system at elevated temperature were performed. The results show that the gas constituents are H20, S02, H2S, Sj, H2, and O2 and the order of the compositions partial pressure is PH2o> PH2 >PSO2 >PSj >PH2S >PO2 when FeS is oxidized into Fe304 and FeO by steam in the temperature of 700°C -960°C, the Claus process occurs with the decrease of gas temperature in the off-gas and the S02 and H2S in the gas are transformed into Sj , the critical temperature for the transformation is 600°C, and conversion percent of Sj is 97% at 330°C,

Jan 1, 1996

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' 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 Qingyu Deng, Shiwei Ma, Wang Hua, Guibao Qiu

"The flow properties of the blast furnace slag bearing high TiO2 at high temperature like the viscocity may change a lot due to the formation of the carbonitride inside, causing serious problems on the separation between the metal and the slag. Therefore, the critical condition of the formation of Ti(C,N) in blast furnace is vital importance for the ironmaking process with iron ore bearing titania. In this study, the formation of Ti(C,N) in blast furnace and the influences of various factors on the Ti(C,N) formation are investigated by FactSage. It is found that the mass of Ti(C,N) would reach the maximum at 1480 oC, and the product is mainly TiN below 1620 oC, while it is mainly TiC above 1620oC. The order of the factors by the importance from strong to weak was: temperature, the content of TiO2 in slag, basicity of slag, the content of MgO and Al2O3.IntroductionThe titanium dioxide (TiO2) in iron ore bearing titania will be partly reduced by carbon to titanium carbonitride (Ti(C,N)) in blast furnace, causing serious problems on the separation between the metal and the slag because of the change of flow property. Therefore, the critical condition of the formation of Ti(C,N) in blast furnace is vital importance for the ironmaking process, especially for the smelting of iron ore bearing titania. Extensive experimental data in regard to the formation of Ti(C,N) has been reported in numerous papers[1-6]. However, only some discrete data can be obtained by experiment, and it is difficult to detect the mass of Ti(C,N) in slag. In addition, the experiment is difficult to be proceeded when the temperature is above 1600oC. Therefore, it is very difficult to make clear the critical condition of the formation of Ti(C,N) by experiment."

Jan 1, 2012

By Shinroku Matsuzaki

Data the measurement sensor installed with spatial distribution on the blast furnace were successively accumulated online from the process computer to the database system over a long period. This is a new system that accurately considers the relation with the installation position of each sensor, and picture computerization of the measurement data was developed. The overall operation state of a blast furnace, which skilled operators can see in their mind?s eye, was objectively visualized as pictorial information.

Jan 1, 2006

By Meifeng Zhi

Separation of uranium and molybdenum in the alkaline leach solution of a U–Mo ore was studied. A process of acidification-solvent extraction-precipitation uranium and molybdenum was determined. The influences of solution acidity and phase ratio of acidic scrubbing on separation of uranium and molybdenum were examined. The molybdenum extraction equilibrium isotherm was drawn. The results show that the separation of molybdenum and uranium can be achieved by acidifying the alkaline leach solution, solvent extracting molybdenum using trialkylamine at equilibrium pH 2.5, and scrubbing the loaded organic phase using sulfuric acid solution. The strip solution can directly precipitate ammonium molybdate. Uranium can be directly precipitated from the raffinat

By Alice Barreto Bevitori, Felipe Perissé Duarte Lopes, Denise Cristina Oliveira Nascimento, Sergio Neves Monteiro, Isabela Leão Amaral da Silva

"The piassava fiber is one of the most rigid natural lignocellulosic fibers, which has since the last decade been investigated as possible reinforcement for polymeric composites. In the present work, the tensile properties of polyester composites reinforced with piassava fibers with thinner diameters were investigated. Composites with volume fractions up to 30% of continuous and aligned piassava fibers were tensile tested at room temperature to evaluate the ultimate strength, elastic modulus and total strain. For each volume fraction, individually separated fibers with the smaller diameters were tested. The results indicated that the tensile properties tend to improve with increasing volume fraction of the thinner piassava fibers. The role played by the fiber/matrix interaction was analyzed by scanning electron microscopy.IntroductionA significant change in the transportation sectors mainly the aerospace and automotive, occurred last century with the introduction of stronger and lighter materials. The most relevant example was the polymer composite reinforced with synthetic fiber. They are nowadays replacing conventional materials such as the aluminum alloys in airplane body owing to superior specific strength. in recent years, however, environmental problems in a global scale are imposing a reversion in the use of synthetic fiber specially the glass fiber. In spite of its higher specific strength, this fiber and its polymer composites can neither be recycled nor incinerated in a thermal plant to generate electricity [1]. Moreover, the fabrication, processing and transportation of a glass fiber composite are associated with C02emission, the major responsible for global warming [2].A possible substitute for glass fiber without the above-mentioned environmental problems, could be a natural fiber. In fact, natural fibers obtained from cellulose-rich plants, also called lignocellulosic fiber, are already being used in several engineering fields, particularly the automobile industry [3-6]. Figure 1 illustrates an automobile and its many components made of lignocellulosic fiber composite [7]."

Jan 1, 2011

By J. E. Klein

Bench scale tests using a stack of ten whole SAES St909 pellets, 6 grams, to crack methane have been completed with pure methane feed. Test conditions ranged from 600 to 800°C at 101 kPa (760 ton) with a methane feed rate of ten sccm. Methane reformation tests, test where hydrogen was passed through a St909 bed after cracking methane, were performed to determine if and how much methane can be generated under "reformation" conditions. Phase structure determinations of St909, composed of a ZrMnFe alloy with aluminum used as a pellet binder, after methane cracking were complicated by the number of materials that can be formed by the elements in the St909 and the carbon from methane cracking. It was determined that the aluminum not only alloys with the Zr, Mn, and Fe in the St909 alloy, but also forms aluminum transition metal carbides in addition to ZrC as the carbon content and the temperature of the St909 increases. Some A14C3 was also found in some pellets. Passing hydrogen over St909 pellets after methane cracking formed methane at various rates in the temperature range of 600 to 800°C. Temperatures of 800°C gave the best methane cracking performance and efficiencies decreased rapidly with temperature.

Jan 1, 2002

By Li Ma, Shaoguo Chen, Gele Qing, Qihang Liu, Keng Wu

Olivine contains higher MgO element, which can be added into blast furnace burden to improve slag stability and fluidity. Effect of calcined olivine and untreated olivine on low silicon pellet production process and quality was studied in this paper. The results shows, calcined olivine has no effect on bursting temperature of green pellet, however the bursting temperature of green pellet will decrease with increase of untreated olivine ratio. Untreated olivine has slight effect on green pellet strength than calcined olivine while the ratio is higher than 2%. The compressive strength of low silicon pellet will increase first and decrease afterwards with increases of calcined olivine ratio under firing temperature of 1250°C, whereas, the changing sequence is reverse fired under 1280°C. The result of untreated olivine pellet compressive strength is same as calcined olivine pellet. However, the compressive strength and metallurgical property of calcined olivine pellet is slightly higher than that of untreated olivine pellet under same condition.

Jan 1, 2015

By Regina Krachler, Herbert Ipser

"The principles of the derivation of statistical-thermodynamic models to interpret the compositional variation of thermodynamic properties in non-stoichiometric intermetallic compounds are discussed. Two types of models are distinguished: the Bragg-Williams type, where the total energy of the crystal is taken as the sum of the interaction energies of all nearest-neighbor pairs of atoms, and the Wagner-Schottky type, where the internal energy, the volume, and the vibrational entropy of the crystal are assumed to be linear functions of the numbers of atoms or vacancies on the different sublattices.A Wagner-Schottky type model is used for the description of two examples with different crystal structures:For B'-FeAl (with B2-structure) defect concentrations and their variation with composition are derived from the results of measurements of the aluminum vapor pressure; the resulting values are compared with results of other independent experimental methods.For Rh3~ (with an NiAs-derivative structure) the defect mechanism responsible for nonstoichiometry is worked out by application of a theoretical model to the results of tellurium vapor pressure measurements. In addition it is shown that the shape of the activity curve indicates a certain sequence of superstructures.In principle, there are no limitations to the application of statistical thermodynamics to experimental thermodynamic data as long as these are available with sufficient accuracy, and as long as it is ensured that the distribution of the point defects is truly random, i.e. that there are no aggregates of defects."

Jan 1, 1996

By Petrus Christiaan Pistorius, Farzin Fatollahi-Fard

The production of synthetic rutile—a common starting material for most titanium production processes—from iron-rich titanium minerals such as pseudorutile and ilmenite is described. The process for “upgrading” the mineral to synthetic rutile is by carbothermal reduction of the mineral while immersed in a molten salt at high temperature, followed by magnetic separation of the reduced iron. A variety of factors are also investigated, such as particle size of the mineral, the type of mineral, and the molten salt used. The solubility of iron(III) oxide in different molten salts is also experimentally determined.

Jan 1, 2016

By T. T. Chen

This mineralogical study is based on samples from typical "wet" nickel laterites of humid tropical to sub-tropical regions. An in-situ nickel laterite sample from Goro and a transported laterite sample from Plaine des Lacs, New Caledonia, are predominantly limonitic. Two-thirds of the particles in the Goro sample are <10 um in size; they consist of skeletal goethite and serpentine, as well as minor amounts of talc, gibbsite, chlorite, quartz and clay minerals. The coarser grains are mainly Cr-spinel, serpentine, gibbsite and Mn oxide. Nickel occurs mainly in goethite, serpentine and Mn oxide; cobalt occurs in goethite and Mn oxide. The Plaine des Lacs sample is finer-grained and contains more Al and CO3, but less Mg and Si than the Goro material. The sample contains more kaolinite, chlorite, siderite and feldspar, but less serpentine and gibbsite than the Goro material. Nickel is detected mainly in goethite, serpentine, Fe-Mg silicate and Fe-Mn oxide. The Indonesian ore from Sorowako, as sampled from the reduction kiln feed containing some reverts, is predominantly saprolitic, with apparent particle sizes ranging from <100 um to > 1 cm. The sample of reduction kiln feed is rich in Mg silicates, Mg-Fe silicates and goethite, and exhibits complex alteration textures. The nickel contents vary from particle to particle. Nickel is present mainly in serpentine, olivine, chlorite and amphibole, and in subordinate amounts in goethite and Mn oxide. Cobalt is detected in the Mn oxide. Keywords: Nickel Laterite; Mineralogy; Nickel Carriers; Goro, New Caledonia; Plaine des Lacs, New Caledonia; PT Inco., Sorowaki, Indonesia

Jan 1, 2004

By Shawn A. Cefalu, Matthew J. M. Krane, Kent J. VanEvery

"Segregation during electroslag remelting (ESR) of a nickel-chromium-molybdenum alloy (Ni-8 wt% Cr-25 wt% Mo) has been modeled. Features of the model include species transport and AC electromagnetic effects coupled with fluid flow, heat transfer, and solidification. The effect of varying ingot diameter and melt rate, on macrosegregation patterns, local solidification time, and liquid pool profiles obtained from this model are demonstrated. The results show that the macrosegregation in the ingots correlates to the filling velocity.IntroductionElectroslag remelting (ESR) is a secondary melting process used to refine the chemical composition and the microstructure of metals. Macrosegregation of solute elements causes defects in ESR ingots, including freckles and the maldistribution of phases. These defects are not correctable through heat treatment due to the large length scales over which they occur. However, the frequency and distribution of these defects may be minimized, or even prevented, through process control based on an understanding of the conditions that lead to their formation.In the past, studies have been conducted on the effect of the process parameters on the shape of the melt pool and the thickness of the mushy zone [1-7]. In these studies, the shape of the liquid pool is determined by consideration of the heat and fluid flow induced by electromagnetic (Lorentz) force and thermal buoyancy. The transport of solute and the resultant solutal buoyancy effects were not considered in these macroscopic models. Defect formation is tied to formation of secondary phases (e.g., freckling and white spots in nickel superalloys) [5,8]. In cases where secondary phase formation is calculated (e.g., [6]), phase fractions are determined using a micro-scale model given the local solidification time (LST) and local thermal history from the macroscale model.Using the local thermal history from the macroscopic transport model to predict microstructure increases the importance of the accuracy of those results. This investigation models the macrosegregation of molybdenum during the ESR of a Ni-Cr-Mo alloy. The effect of macrosegregation on pool shape and depth is demonstrated, along with its effect on the local solidification time. By comparing the relative effects of the melt rate and ingot radius, a better understanding of the factors that affect macrosegregation, and ultimately secondary phase formation may be obtained."

Jan 1, 2004

By Robert H. Hsu

Palladium finely dispersed in a substrate of kieselguhr, Pd/k for short, has been successfully used for hydrogen storage, separation and pumping for a number of years at the Savannah River Site (SRS). Recently SRS has developed a new pd/k flow through bed (FTB) prototype for separating hydrogen from other gases and simultaneously storing the hydrogen on palladium. The FTB uses single-pass liquid nitrogen cooling during hydrogen absorption/separation/storage and electrical heating for desorption/unloading of hydrogen. Fourteen absorption-desorption or loading/unloading cycles using hydrogen have been conducted with the new FTB prototype. Test results show that all design performance objectives have been successfully achieved: recover 295% of hydrogen gas from feed gas, produce 99.9% hydrogen product gas and < 5% hydrogen in discharge gas. This paper will discuss characteristics of the palladium-coated kieselguhr or diatomaceous earth, design and operation of the FTB, and results of performance tests such as separation efficiency, hydrogen storage capacity and system heat transfer characteristics.

Jan 1, 2002

By L. Katgerman, R. Van Toi, H. E. A. Van den Akker

"Mould filling simulations are powerful tools for optimizing the characteristics of castings. The robustness of calculational methods for mould filling simulations is generally tested in simple geometries. While a vertical plate has been used often for validation studies, this paper aims at mould filling simulations of a horizontal thin wall casting. Such castings exhibit a strong interaction between heat transfer (solidification), surface tension and gravitational force.The results are presented of a study to validate numerical simulations of mould filling phenomena in a thin wall horizontal casting. Solidification during mould filling is studied computationally. Velocities are measured using Particle Image Velocimetry.INTRODUCTIONIn foundry practice Computational Fluid Dynamics (CFD) is being considered a promising tool to arrive at a better understanding of casting defects introduced during the mould filling period of a casting. The use of CFD is believed to be advantageous in predicting possible defect locations, pouring times, and the lowest possible casting temperature without the risk of cold shuts. In addition, CFD may be used to optimize pouring system geometries [1,2]. As opposed to experimental studies in, e.g., cold water models, CFD allows for the flexible modification of the casting geometry and the pouring system, and for the inclusion of physical effects such as solidification and heat transfer. Thus, a proper use of CFD may lead to a reduction of the casting rejection rate without expensive trial-and-error procedures, and to a decrease of production costs in foundries. Mould filling simulations take a special place in CFD, because a free surface tracking algorithm is required. Over the past decade methods, MAC [3] and SOLAVOF [4], have been extended to 3-D. The robustness of computational methods for mould filling simulations is generally tested in simple geometries [5,6]. While a vertical plate has been used often for validation studies, this paper concentrates at mould filling simulations of a horizontal thin wall casting. Thin wall horizontal castings exhibit a strong interaction between heat transfer (solidification), surfaces tension and gravitational force. The gravitational force in this setting is orthogonal to the plane of flow and has therefore no influence on the shape of the free surface in the plane of flow. Mould filling numerical methods and algorithms have been recently reviewed by Chen et al.[7]."

Jan 1, 1999

By W. R. Opie

Fundamentals of blast furnace smelting of low grade copper and precious metal scrap and residues are reviewed with emphasis on emission control, by-products produced, slag cleaning for high recovery of metal values and the evolution of an off-gas system to eliminate hydrocarbons that result from decomposition of plastics in the blast furnace- charge. Problems with tin, antimony and nickel in the smelter-refining cycle are discussed.

Jan 1, 1985

By Hidefusa Takahara, Koichi Miyake, Dierk Raabe

"Mechanical properties of copper wires were examined. The copper wires containing 5-10 mass % chromium and 1-3 mass % silver were produced through heavily cold deformation. It was expected that the copper wire was easily fractured during cold deformation because of the existence of brittle chromium phase in the alloy. In fact, the copper wire was fractured due to large work hardening, when the true strain [n] exceeded 5. However, the copper wire annealed at 1273K for 6 ks ·in the middle of deformation process could be smoothly drawn to 11=8. After precipitation treatment for silver phase at 473k for 1.8 ks, the wire was able to further drawn to n=8.4. The final deformed wire showed tensile strength higher than 1200MPa.IntroductionDownsizing of electronic devices has led to the demand of finer and higher strength materials for cables. Conventional copper alloys have about 800MPa in ultimate tensile strength. These strength are mainly obtained by precipitation hardening. Nowadays, a process for higher strength wire has been developed, where dual phase copper alloy is used. When it is drawn heavily, the' second phase is elongated along drawing direction and the wire gets high strength due to fiber reinforcement (1). That alloy is so called in-situ formed fiber reinforced ·alloy. Cu-Ag(2), Cu-Nb(3) and Cu-Cr(4) systems are well known as such alloys. It is also well known that chromium is brittle material except single crystal and high purity of chromium. However, Mihara et al. C5l have achieved 1 GPa in ultimate tensile strength in the Cu-Cr-Zr and Cu-Cr-Ti alloys by appropriate thermo-mechanical processing.In this study, the Cu-Cr-Ag systems were investigated: The alloys contained 10 or 5% chromium and 3 or 1 % silver. It was demonstrated that silver precipitated in copper matrix contributed on further hardening."

Jan 1, 2000

By G. Fazel Jahromi

Enargite, known as one of the major arsenic containing copper minerals, with approximately 19% arsenic, introduces challenges to typical processing options. In most hydrometallurgical processing methods, arsenic remediation occurs after the copper recovery in an autoclave or in a stepwise neutralization process. In this study, the in situ precipitation of scorodite was investigated during an atmospheric leaching process in the presence of carbon-based catalysts and chloride media. The effective parameters of initial ferric addition, temperature, catalyst addition, and oxygen sparging rate were studied and the ferric behaviour was monitored during the scorodite precipitation. The most influential parameters on efficient scorodite precipitation are found to be: initial ferric addition, catalyst to concentrate ratio, and temperature. A 99% scorodite precipitation yield was achieved in this process.

By R. Boom, Y. V. Meteleva-Fischer, B. Kraaijveld, H. Kuntzel

"Segregation of impurities during refining of metallurgical grade silicon (MG-Si) is an option to produce solar grade silicon (SG-Si). Directional solidification is a last step in production of SG-Si effective for removal of metallic impurities. The possibility is investigated to use metallic impurities originally present in MG-Si for removing boron and phosphorus. MG-Si has been treated using two methods: 1) alloying with calcium and 2) refining with Na2O-CaO-SiO2 slag, both by controlled cooling. The microstructure of silicon and the impurities distribution have been studied before and after the treatments. Using EPMA phosphorus and boron have been detected in 1-2 wt% concentration range in several intermetallic compounds in grain boundaries after both treatments. This observation points to a different possible mechanism of silicon refining from boron and phosphorus. Controlled cooling improves migration of phosphorus and boron to the silicide phases in grain boundaries, which can be removed by acid leaching treatment.2. IntroductionStandards for silicon solar cells and growing demand on “green” energy require economical and efficient route to the production of solar grade silicon. Refining of cheap metallurgical grade silicon is one of the promising options, where application of existing metallurgical approaches can result in cost-efficient production on industrial scale. Focus in refining is on impurities, which are most difficult to remove: B, P, Al, Ti, due to their large segregation coefficient in silicon and low vapour pressure [1]. Moreover, more environmentally friendly technology in comparison to the traditional Siemens process [2] will be in accordance with societal needs. Based on properties of common impurities in metallurgical grade silicon, alloying refining and slag refining are suggested as competitive techniques having potential effect on removal of impurities harmful for conversion of solar energy [3, 4]. Alloying with Ca followed by acid leaching was found to be effective for removal of Fe and Ti from silicon [5] and to enhance also removal of boron [6] and phosphorus [7, 8]. In the work of Inoue et al. [8] drastically increasing removal of phosphorus from silicon has been observed with an increase of Ca content and a thermodynamics-based explanation was provided. Since phosphorus has been found to condense in the secondary precipitate mainly composed of CaSi2, it can be removed together with iron and titanium by consecutive acid leaching treatment. Slag refining is one of the metallurgical methods proposed to be effective for refining of metallurgical grade silicon from boron [9, 10]. Slags with additions of the following oxides to silica have shown positive effect on removal of boron: CaO [11-13], Na2O [11,14]. Mechanism of slag refining from boron is based on oxidation of boron followed by its incorporation in the slag network [9,11]; the same mechanism is suggested for refining from phosphorus taking into account that oxides of boron and phosphorus are known as network-formers [15]."

Jan 1, 2012

Proposed by outstanding electrochemist and electrometallurgist Prof. Raphael Agladze (191 1- 1989), process of copper and manganese co-electrowinning was enhanced to the pre- electrowinning stages: low,temperature co-leaching of copper and manganese containing materials, and to high-temperature co-roasting of the same materials with consecutive leaching. The report presents results of experimental investigations of the processes mentioned above, as well as results of thermodynamic investigations of co-roasting processes, and co- leaching processes computer modeling.

Jan 1, 1997