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By David R. Brosnahan

Increased Cu grades due to chalcopyrite-rich ore from The Doe Run Company's new Casteel Mine prompted a program to increase Cu recovery. Preliminary tests indicated that prohibitive quantities of FeS2 float with chalcopyrite. Point counting of mill stream samples showed that locking was not a major problem, although grinding to finer particle size enhanced the floatability of both chalcopyrite and marcasite. Backscattered electron images and microprobe analyses of FeSz minerals revealed the presence of Pb which appears to occur as solid solution in marcasite, and as a sub-micron particulate Pb phase in pyrite.

Jan 1, 1987

By R. Hamar, G. Lamanthe

"To realize complex shaped pieces, like turbine blades, superalloys are cast with the lost-wax process. The end properties of these parts depend upon their microstructure as well as upon the occurence of casting defects such as micropores and hot tears. Such features are governed by the local solidification conditions which may be describe by the calculation of thermal transfers between alloy and mould. It needs the evaluation of numerous parameters which are fitted from experimental measurements in real castings. In further simulations, any parameter may be changed, in order to determine its influence. Such a single modification is quite impossible to realize in real castings, which shows that numerical modeling is a very good way to study casting processes.This modeling technique of casting is applied here to the real study of a typical low pressure turbine blade of a civil engine.IntroductionAircraft engine manufacturers use superalloys to produce turbine blades. They have to obtain a given microstructure and to avoid solidification defects to give good mechanical properties to theirs castings. For example, microporosity is induced by a large shrinkage that cannot be completely fed with the remaining liquid alloy .The optimization of casting processes needs a good Knowledge of the solidification process, that must be controlled at every place in the casting, and at every time of its freezing. Material and heat transfers that occur during the solidification, can be estimated from rather complex calculations. To model these physical phenomena, the evaluation of many parameters must be made. In this aim, some casting experiments are fitted with numerous thermal captors. The identification of experimental and computed thermograms let us estimate these parameters.A long-range scientific cooperation between SNECMA and INPG has enabled the realization of such studies on this topic. From all of them, this paper describes an experimental and computed investigation which has been led on a typical low pressure turbine blade of a civil engine."

Jan 1, 1986

By Y. Suzuki, J. Nagao, Y. Ueda, K. Shimokawa

"A Ti- Ni intermetallic compound could be formed rapidly from Ti and Ni powder compact with SHS process. Microgravity experiments using a drop shaft are carried out, This report shows the effect of microgravity or high gravity on formability of an intermetallic compound. It is concluded that the specimen forms a porous and nearly amorphous alloy by rapid cooling under microgravity but with rapid cooling under high gravity after microgravity, the specimen forms a uniform and dense structure with better crystallinity.IntroductionTi - Ni inter1etallic co1pounds have been produced and have beco1e si1ilar to the a1orphous and porous structure as a result of the SHS (Self Propagating High-te1perature Synthesis) process under 1icrogravity. SHS process is being applied to the synthesis of cera1ics and inter1etallic co1pounds (1). The technique is characterized by a large a1ount of heat being emitted within a very short ti1e interval as regards the sistering reaction. One SHS process, acco1panying 1elting by a reaction was observed, and that was due to the quick heating of a Ni-Ti co1pact containing 50 ato1ic percent of Ti under a low pressure (2-4). In this report, we have researched the use a drop shaft which is 1ore effective during a short ti1e under 1icrogravity and high-gravity, so as to obtain high dense speci1ens with the exception of porous specimens (5). Mechanical properties of each specimen were esti1ated from these 1icro-structures with a discussion about the effect of changing gravity regarding 1elting and solidification of the Ti-Ni intermetallic comounds."

Jan 1, 1996

By Hélio Wiebeck, Fabio J. Esper, Wildor T. Hennies, Guillermo R. Martín-Cortés, Francisco R. Valenzuela-Díaz

"Natural rubber reinforced commonly with carbon black to produce vulcanized material, turns into a new environmentally friendly nanocomposite when carbon black is replaced by organically modified clays of Brazil. Carbon black is substance derived from the oil refining process with consequent pollution to the environment. Its substitution in this industrial process must contribute to diminish the oil derived products dependence. As the added clays are only a third in weight of the traditionally carbon black added, then, to obtain the same final volume it is necessary to add low cost neutral filler that does not damage the technological characteristics of the final material. This paper presents results using as neutral filler of this type rice husk ashes from industrial wastes. Experiences realized with this nanocomposite material show results of quality and technological characteristics similar or superior to those of the rubber made with carbon black.IntroductionTraditionally rubbers are black or a very dark color. But they can have different appearance when filler of distinct composition of the carbon black is used. The carbon black is substance derived from the oil gotten during the final phases of the mineral fuel treatment with consequent pollution of the environment. Carbon black show nanometric grain sized distribution and a depth black color, because these properties it is also used for computer printers inks production. The substitution of this substance, traditionally used as a reinforced load in the rubber production, will have to contribute in such a way to diminish the dependence of these products as to diminish the pollution of the environment. The present work shows the results of the use of another kind of mineral nanoparticulate material substituting carbon black in the production of some rubber products. This nanoparticulate material is the organic modification of smectite clay treated with some types of ammonium quaternary."

Jan 1, 2008

By Denise Cristina de O. Nascimento

Natural lignocellulosic fibers are increasingly being used as polymeric matrix composite reinforcement owing to economical and environmental advantages as renewable and biodegradable materials. Among these, the piassava fiber extracted from a palm tree native of South America stands as one of the most rigid with a potential to be used as composite reinforcement. Therefore, the present work investigates the notch toughness behavior, by Izod impact tests, of epoxy composites reinforced with up to 40 % in volume of continuous and aligned piassava fibers. It was found that the incorporation of piassava fibers results in significant increase in the impact energy of the composite. Scanning electron microscopy analysis showed that the nature of the piassava fiber interface with the epoxy matrix is the major responsible for the superior toughness of the composite.

Jan 1, 2009

By Xiaoyan Xiang, Wenqiang Yang, Wentang Xia

Magnesium aluminate spinel is widely used in the metallurgical industry as refractory material, however, natural magnesium aluminate spinel is rare and most of the magnesium aluminate spinel is synthetic. The traditional synthesis of magnesium aluminate spinel often needs high temperature, which leads to more energyconsumption. In this article, solid phase sintering process was employed to synthesize magnesium aluminate spinel, in which, magnesium and aluminum oxide were used as raw materials and magnesium and aluminum powder were used as composite additives. The mass ratio of magnesium and aluminum on the effect of synthesis of magnesium aluminate spinel and the characteristic of the synthesis at different temperature and time was discussed. Experiment found that the synthesis temperature was observably lowered when the addition of magnesium and aluminum was 2.0% and 1.0% respectively.

Jan 1, 2016

By Supachai Surapunt

The distribution behavior of V A minor elements (As, Sb and Bi) in the smelting stage of the Mitsubishi process were evaluated thermodynamically based on thermodynamic data and operating data. The fractional distributions between the gas, slag and matte phases considered as the degree of vapor saturation of 1.0 are as follows: 53.8, 27.2 and 19% for As, 23.6, 56.6 and 19.8% for Sb, and 91.3, 1.1 and 7.6% for Bi, respectively. Arsenic is mostly distributed to the gas and slag phases. It is effectively eliminated by volatilizing and slagging. Antimony is mainly in the slag phase, which is suitably removed by slagging. Bismuth is easily vaporized to gas phase. The degree of vapor saturation has a large effeet on the distribution behaviors of the three elements between the three phases. The amount of a minor element in the charge has an effect on the distribution of As but no effect on the distributions of Sb and Bi. Increasing matte grade and temperature results in the change of distributions for As and Sb, significantly. The change in the distribution ratio between slag and matte phases also considerably affects the distributions of As and Sb. The distribution behavior of Bi is not significantly changed by the change in matte grade, temperature and distribution ratio.

Jan 1, 2003

By N. M. S. Balbinot, A. L. Rodríguez, C. M. Mahlmann, R. de C. de S. Schneider

The use of sunflower oil co-products it was studied for production thermoplastic composites. Thermoplastic composites have been processed in polyethylene matrices of virgin linear low density polyethylene (LLDP) or recycled. Samples have been formulated with 10% mass fraction of sunflower bran, seed coat and mixture of bran and seed coat. The material characterization has been achieved by mechanical tensile test and Shore D hardness and by density physical testing. The results have demonstrated better properties to thermoplastic composites with sunflower seed coat.

Jan 1, 2008

By Tianzu Yang, Weifeng Liu, Lin Chen, Deyu Wang

"Due to the gradual exhaustion of easily extractive gold ores, it is vital to make efficient use of refractory gold ores which hold 30% gold storage of the world. However, the disadvantage of current processing technologies for refractory gold ores consists of severe pollution, low gold extraction ratio, high investment, etc, thus great research interests were attracted during recent years. This article provides an overview of the distribution and categories of the refractory gold ores in the world. The state of art in processing refractory gold ores by pyrometallurgy, hydrometallurgy and biometallurgy techniques and their industrial applications are highlighted. Potential environmental conservative techniques for efficient gold extraction are also reviewed.IntroductionResources of Refractory Gold OresAs easily extractive gold ores are going to be exhausted with the large scale mining nowadays, refractory gold ores are becoming more and more important. Gold in the refractory gold ore cannot be fully extracted using conventional method (cyanidation) even with fine grinding. The amount of gold in the refractory gold ores is about 1500~2000t in China, which occupies 30~40% of the total gold storage [1]. Therefore, it is vital to make efficient use of refractory gold ores."

Jan 1, 2013

By Pan Gu, Zhen Zhang, Jiang Diao, Bing Xie, Hongyi Li

Furnace refractories are in most cases chemically incompatible with smelter slag, which leads to a steady erosion in their thickness over time. Once too thin, refractory walls become mechanically unstable and catastrophic failure can result. Historically, external shell cooling was applied to generate a freeze lining of slag and thus prevent refractory erosion. Many modern high intensity smelting furnaces instead maintain their physical integrity by the use of internally cooled wall panels, plates or finger coolers. An initial refractory lining is often installed inside of the coolers, such that the furnace originally operates with a temperature (insulated) rather than a heat flux (freeze lined) boundary condition. This paper examines the change in slag-wall heat transfer coefficient and slag superheat as a function of process intensity. The implications of the changes in heat transfer on residual brick thickness are explored using analytical modelling.

Jan 1, 2016

By Kotaro Ogura

"Ethylene has been produced in aqueous solution from CO2 by the electrochemical reduction driven by a natural energy. This process is useful for storing a large amount of the natural energy. In the closed system, the conversion efficiency of CO2 is almost 100%, and the maximum selectivity for the formation of ethylene is more than 70%. On the other hand, the current efficiency for the competitive reduction of water is less than 10%. The electrolysis is practicable under such special conditions as three-phase interface consisting of gas, solution and metal, concentrated solution of potassium halide, low pH and copper or copper halide-confined metal electrode. These requirements are thoroughly examined, and the grounds to reply upon are revealed. A series of chemical apparatuses including an electrolytic cell in a large scale are designed for the ethylene production, which allow us continuously to supply raw CO2 and to extract the product.IntroductionIn connection with the depletion of the petroleum reserve, much attention has been paid to the utilization of natural energies such as sunlight, wind force and waves. However, these energies are always changeable, and some means of storing them are necessary for the common use. In general, natural energies are transformed to the electric energy at the time of utilization, but the electricity is not very storable. This is one of the reasons why the application of natural energy is not so expanded. On the other hand, the storing of natural energy by plants is very skilful. In the photosynthesis, solar energy is transformed to chemical energy by fixing carbon dioxide."

Jan 1, 2009

By G. L. Pedroti

With the development of industrial processes and the consequent emergence of numerous products that quickly become necessities, industrial activity has acquired an essential character today. Although its importance is unquestionable, industrial activity is responsible for generating quite a large number of residues, with different shapes and characteristics. It has been observed, in particular the grits (Kraft process in the cellulose industry) and the residue from the processing of granite. And, given the importance of Portland cement as a building material, its vast employment and waste properties that resemble components of the clinker, it was decided to produce cementitious compounds from these industrial wastes. The residues were subjected to mineralogical, chemical, physical and morphological. And, the mixing ratio between the residues in the 70% and 30% grits residue granite was sintered at 1250 ° C furnaces to burn threshold of 6 hours forming new compounds observing tri-calcium aluminate and di-calcium silicate that are compounds found in portland cement.

Jan 1, 2015

By Guojun Qi

This work relates to wafer bumping technologies for flip chip packaging applications in the electronics industry. Nickel and its alloys are alternative under bump metallization (UBM) materials because of their slower reaction rates with Sn-based solder as compared to Cu-based UBMs. In this study, we compared the morphologies of the intermetallic compounds (IMC) formed between Sn-bearing solders (Sn3.5Ag and eutectie Sn-Pb) and two types of nickel- based UBMs, electro less Ni-P (EN) and sputtered nickel. Both chunky-type and needle-type of intermetallics were observed between the EN UBM and the solders. In the case 'of sputtered Ni UBM, there is only a layer of scallop-type intermetallics formed, The morphology change and growth kinetics of the IMC in thermal aging process were analysed. Kirkendall voids were noticed from samples ofSn3.5Ag solder vs Ni-P UBM that have undergone prolonged thermal aging at high temperature.

Jan 1, 2003

By Guojun Qi

This work relates to wafer bumping technologies for flip chip packaging applications in the electronics industry. Nickel and its alloys are alternative under bump metallization (UBM) materials because of their slower reaction rates with Sn-based solder as compared to Cu-based UBMs. In this study, we compared the morphologies of the intermetallic compounds (IMC) formed between Sn-bearing solders (Sn3.5Ag and eutectic Sn-Pb) and two types of nickel- based UBMs, electroless Ni-P (EN) and sputtered nickel. Both chunky-type and needle-type of intermetallics were observed between the EN UBM and the solders. In the case of sputtered Ni UBM, there is only a layer of scallop-type intermetallics formed. The morphology change and growth kinetics of the IMC in thermal aging process were analysed. Kirkendall voids were noticed from samples of Sn3.5Ag solder vs Ni-P UBM that have undergone prolonged thermal aging at high temperature.

Jan 1, 2003

By Mark Jolly

"Instead of using the traditional batch casting process, the CRIMSON [1] (Constrained Rapid Induction Melting Single Shot Up-Casting) method employs a high-powered furnace to melt just enough metal to fill a single mould in a closed crucible. The crucible is transferred to a station for computer-controlled counter gravity filling of the mould for optimum filling and solidification. The CRIMSON method therefore holds the liquid aluminium for a minimum of time drastically reducing the energy losses attributed to holding the metal at temperature. With the rapid melting times achieved, of the order of minutes, there isn’t a long time at temperature for hydrogen to be absorbed or for thick layers of oxide to form. The metal is never allowed to fall under gravity and therefore any oxide formed is not entrained within the liquid. Thus higher quality castings are produced leading to a reduction in scrap rate and reduced overall energy losses.IntroductionEngineers at the University of Birmingham, England, with local company, NTec, have invented a new casting process that will reduce the energy costs of light-metal foundries. The technology, entitled CRIMSON, means that foundries need only heat the quantity of metal required to fill a single mould rather than large batches that use unnecessary energy and create waste. The complete concept of CRIMSON requires a change of philosophy in the approach to casting and requires the user to think holistically in order to reap the full benefits from the process. This paper will discuss the various aspects of energy wastage within the foundry sector and discusses the processes whereby the energy can be reduced. Primarily the author focuses on the aluminium sector but CRIMSON can be applied to many of the non-ferrous “light” alloys. Ferrous materials and non-ferrous “heavy” alloys can also benefit from some of the ideas but not necessarily directly from the application of CRIMSON."

Jan 1, 2010

By Natasa Mitevska

In order to ensure the minimal copper concentration in the reverb furnace slag, the graphical optimization method is used and the optimal slag composition of the reverberatory furnaces No.1 and No.2 in the RTB BOR, Copper Smelter and Refinery (Serbia) is obtained: (Si02) .. 38.0%; (FeO) .. 40.0%; (Fe3O4) = 5.0%; (CaO) = 5.0%; (Al2O3) .. 6.0%. Keywords: Optimization, Reverb Furnace Slag, Graphical Method

Jan 1, 2003

By Reza Kamali, Mohsen Bashiri, Hadi Fanisalek

"Nomenclature: A: area (m2), C: heat capacity (WIK), cp: specific heat (J/Kg K), d: internal tube diameter (in), F: correction factor for multi-pass and crossflow heat exchanger, h: convective heat transfer coefficient (W/m2K), k: thermal conductivity (W/mK), L: length (m), m: mass flow rate (Kg/s), W: flow rate, N: number, Q: heat rate (W), R: thermal resistance, T: temperature (°C), U: overall heat transfer coefficient (W/m2K), ;1,,P: pressure drop (Pa), ;1,,T: temperature difference (°C), p: density (lb/ft3), N: number of tube passes, U,: velocity in tubes, iJh: head loss in feet of flowing fluid, Up: velocity in the pipe leading to and from the heat exchanger (ft/sec), µ: viscosity ( cp ), Llpf frictional pressure loss (psi/l 00 equivalent ft of pipe) Subscripts: b: baffle, c: cold, cf counter flow, ex: exchanger, f: fouling, h: hot, i: inlet-inner, ib: inlet baffle, lm: logarithmic mean, m: mean, o: outlet-outer, s: shell, t: tube, w: wall AbstractThe main bottleneck for primary aluminum production industry is dealing with a huge amount of input energy. The fact is that part of provided energy to aluminum production smelters will be lost as waste heat and it never used for aluminum production. One part of waste heat is escaping from the potroom exhaust gases, which was studied for possible recovery in a desalination plant to produce distilled water and the paper was presented in 2011 TMS Annual Meeting. However, it was shown that waste heat recovery plant to produce distilled water is highly profitable but the main fact is that the exhaust gases from potroom are highly corrosive, abrasive and dusty. The main challenge for desalination plant construction, which is using aluminum smelter exhaust gases as the main heat source, is the highly corrosive environment that makes the situation difficult and complicated for equipments design and plant construction. In this paper, we are trying to study a detailed investigation regarding the heat exchangers fouling, corrosion in heat exchangers including heat exchangers' material, how often we need to shut down the plant for maintenance or cleaning, and plant thermal efficiency with considering fouling."

Jan 1, 2012

By T. Plikas, L. H. Gunnewiek, L. Oshinowo

"Electric furnace smelting is one of the principal unit operations for ferroalloy production, and increased process intensity, improved availability, minimal maintenance and a longer campaign life are common objectives for electric furnace operation in order to obtain favourable economics of production. Furnace designers have continued to develop innovative solutions, e.g., furnace cooling systems, that have allowed these objectives to be realised and CFD modelling plays a key role in the design process. Enhanced understanding of the energy transfer process in the furnace and the ability to develop, evaluate and optimize components of the crucible design to match process requirements are the key motivators for modelling.This paper provides an overview of recent applications of CFD to the design of electric furnaces. The aim is to illustrate what can be done, and identify areas where further work is needed in this field. Examples include furnace bath simulation, crucible cooling system design, taphole design, baking of Soderberg electrodes, off-gas systems, and fume control and building ventilation. It is argued that the trend is for numerical models to become more encompassing while at the same time more accessible, and therefore further improvements in furnace design will be realised with continued and well validated modelling efforts.IntroductionOne of the main processing steps in ferroalloy production is the smelting of ore in electric furnaces. The three-electrode, AC submerged arc furnace is most prevalent method for smelting in the industry, with shielded-arc and DC plasma arc furnaces achieving limited application (1,2). Commercial furnaces range in size from a few megawatts to more than eighty megawatts of supplied power, and operate with the objective of maximising the return on capital invested. Maximising productivity and energy efficiency are two pathways to achieving this objective, through process intensification, increased availability, minimal maintenance, and increased campaign life for the furnace and associated equipment. Concurrently, the need to reduce the environmental impact of metal production by controlling the emission of particulate emissions, greenhouse gases, and other harmful by-products must also be met."

Jan 1, 2004

By L. A. André Santos

Atmospheric processing of nickel lateritic ores with low costs has been encouraged. In this work the kinetic of atmospheric acid leaching of a northern- Brazilian ore with 1.63% Ni and large amount of fine particles (d50 ≈ 0.075 mm and 40% below 0.038 mm) is presented. Chemical analysis showed a trend of Ni and Fe concentration in finer fraction (−0.075 mm) and Si and Mg in the coarsest one (−0.500 + 0.150 mm) associated to distinct mineral phases. Nickel is widespread in the mineral matrix. Distinct behaviors were observed as a function of particle size associated to the distribution of silicates and iron oxides in the ore. The kinetic modeling indicated that leaching is controlled by porous layer diffusion at 65 °C, but at 95 °C exhibits a mixed control by porous layer diffusion in initial minutes (60 min) and by chemical reaction or diffusion through the pore layer in final minutes (60–240 min) depends on metal evaluated.

By Shigehito Deki

"A new wet process has been developed for the synthesis of various kinds of oxide thin films on various kinds of substrates, even which have complex surface morphology, from aqueous solution. The process was named as the LPD, Liquid Phase Deposition, method, which has some advantages over the conventional dry processes. This process can be applied to an on-site synthesis of advanced materials in the thin film technology. In this paper, some current topics on the synthesis of the composite thin oxide films by the LPD method, are presented.IntroductionGenerally, metal oxide thin films have been made by different preparative processes such as r.f. sputtering, chemical vapor depositon, CVD, laser ablation and sol-gel method, etc [1-3]. Each method has it own advantages and disadvantage. In some cases, the process is not suitable for the preparation of thin film on substrate with large surface area or complex surface morphology, and makes the deposition apparatus complicated and expenisve. By using Liquid Phase Deposition, LPD, method which overcomes some of those problems, metal oxide or hydroxide thin film can be formed on the substrate with large surface area and complex surface morphology, which are immersed into the aqueous solution only at ambient temperature and under atmosphere without any special equipments and high energy. And also, multicomponent oxide thin films can be formed readily by mixing solutions containing the objective metal ions, because it is performed in the aqueous solution which is typically a homogeneous mixing system. This process utilizes ligand-exchange, hydrolysis, equlibrium reaction of metal-fluoro complex species, MF x (x-2n>-, and F consumptive reaction. In the aqueous solution, MFx<x-2n>-is hydrolyzed with water to release F ions by a ligand exchange equilibrium reaction as following;"

Jan 1, 2000