Search Documents

By Kazuyoshi Sato, Keizo Uematsu, Nozomu Uchida

"Confocal fluorescence scanning laser microscope was applied to characterize the surface flaw of ceramics in great detail. A high potential -of the characterization technique is presented first. Then the technique was applied to clarify the relationship between the flexural strength of ceramics and the surface flaw. This kind of direct information of surface flaw should be essential for the fundamental study in this area, but has been lacking. The examination revealed that large defects are present on the machined surface of ceramics. Their size is consistent to the flexural strength measured on the material. The characterization tool was also applied to examine the formation of surface flaw in machining of ceramics.IntroductionClarification of fracture origin should be the starting point in the study on strength in ceramics. However, this task has been extremely difficult in some ceramics, such as an alumina ceramics. It may break from both internal and surface flaws. The former should reflect the quality of production process and the latter the machining. Examination of surface flaws should be very important for developing a better machining method for ceramics. The knowledge may valuable for establishing a better production process also.ExperimentAlumina Referceram (JFCC) was used as samples. They are cut to size of 3x4x40mm, and the surfaces were ground to meet the requirements of testing method for flexural strength of fine ceramics, JIS R 1601. They were soaked in an aqueous solution of fluorescence dye and evacuated with an aspirator for an hour to allow the solution penetrate into surface flaws. After excessive solution remained on the surface was removed by gentle washing, the specimens were dried at 120°C for 48 hours. The 4 point bending mode was applied to measure the fracture strength."

Jan 1, 2000

By Jiu-ju Cai, Wen-caho Liu, Fei Liu

"With the northern cities of China as study objects, and to confirm Ground-source heat pump system of the environmental benefit and the developing direction. In this paper LCA was applied to the environmental benefit Ground-source heat pump System from raw materials acquisition to system production, utilization and disposal. The conclusion shows that Ground-source heat pump system of the environmental benefit in the northern cities of China. The result showed that Ground-source heat pump system had remarkable environmental benefit. 1. Introduction Life cycle assessment Originate in the sixties of last century, what it paid close attention to is to obtain processing from products raw materials, the processing of products produces, products transportation, products use and maintain to the influence to environment of course. It is a products -oriented environmental management style, it is the environmental management mode of meeting the needs of sustainable development strategy [1]. The research object was in the city and lie in the North of China, would undertake Beijing Olympic Games some football matches in the second half of 08, in order to improve the local environment, adjust the energy structure, reduce the heating consumption of urban coal in the centre, eliminate the coal-burning boiler under 10 tons, since 2005, the local government promotes and utilizes actively the heat pump technology in the source substitute the heating of coal-burning boiler. At present, this area is adopted the technological heating area of heat pump of source reach 20 million square meters, account for this area heat 11.2% of area always, it is estimated, by 2010, adopt the technological heating area of heat pump of source will reach 65 million square meters, the proportion of the area rises to about 30% to account for this area and always heat [2 ]. Study to the whole lifespan of heating system of heat pump of ground source of this area on the basis of LCA method, obtain the products impact on environment of different stages and environmental benefit, find out and reduce or dispel the measure of the influence, improve the environmental benefit of the ground source heat pump heating system.2. MethodologyThe research approach used in this research is the Life cycle assessment, the frame of the research approach is goal and scope definition, the inventory analysis, impact assessment, interpretation.[3][4][5]"

Jan 1, 2008

By Guillermo Rios, Arbizum Cristina, Joa Viflals, Alba Sunyer

"Atlantic Copper is one of the largest copper producers in Europe. Its production facilities are located in Huelva (Spain) and account for the smelting of over one million tpy of concentrates to produce up to 260 ktpy cathodes and 900 ktpy of sulphuric acid. During copper concentrate smelting, the slag coming from the flash furnace and PS converters are treated in an electrical slag cleaning furnace. As a result of the treatment of the off gases from this furnace, approximately 2,000 tpy of a Zn-rich filter cake are produced and are sent to authorized waste managers. This paper describes the characterization of this material and the preliminary results of a new process to recover zinc as a pure zinc hydroxycarbonate while lead is collected as an indium-rich anglesite product. The behavior of impurities (Cd, As, Tl, Sn, Sb, Bi, Cu, Se, Te) in the leaching, solution purification and precipitation steps is also reported.IntroductionThe Atlantic Copper Metallurgical Complex in Huelva (Spain) was commissioned in 1970 with a capacity of 40,000 tpy of copper from concentrate. In 1975, the old blast furnaces were replaced by Outokumpu flash smelting furnace (FSF) technology, and the copper refinery capacity was increased to 108,000 tpy. Between 1994 and 1996, an expansion project was carried out to increase the copper from concentrate and cathodes to 250,000 tpy and 215,000 tpy, respectively. This expansion basically consisted of a new sulphuric acid plant, replacement of the anode furnaces by two 400 t units, redesign of the slag cleaning furnace (SCF), an increase in the electrolytic cells to 1,120 and implementation of ISA permanent cathode technology. Furthermore, a debottlenecking project has led to a capacity of 1,000,000 tpy of fresh concentrate since 1997. Meanwhile between 1995 and 1998, a cathode production rate of 260,000 tpy was reached as a result of a progressive increase in the current density in the refinery."

Jan 1, 2012

The increasing need for robust pyrometallurgical furnace construction is driven by two trends in the copper and other base metals smelting industry: ? the desire for increased production within a single furnace line by greatly increasing smelting intensities, which generates high heat fluxes to the crucible. walls, and ? the operational and economic imperatives of maintaining high percentage on- line times and long campaign lives between rebuilds. A key feature of furnaces capable of producing at high rates, while containing intense processes, is a strong, thermally robust wall cooling system. Equally important design aspects include the furnace steel structure, refractories, a cooling water supply and piping arrangment for safety from leaks and disruptions, and instrumentation/controls for monitoring and rapid mitigation of process excursions. Integration of the cooling elements into these furnace systems is essential for optimum performance of the cooling elements, and indeed the entire furnace. This paper discusses the development of a composite copper / refractory water- cooled design, which has been successfully implemented on several copper smelting and converting furnaces, including Kennecott's flash converting furnace, INCO's MK reactor, and Kidd Creek's converting furnace.

Jan 1, 1999

By N. R. Green, N. J. Humphreys, D. McBride, T. N. Croft, M. Cross, D. M. Shevchenko

"Centrifugal casting offers a route to high quality products in difficult to cast high temperature low superheat alloys and thin section molds. Under centrifugal forces metal is forced into thin sections and can fill thicknesses of less than a millimeter. However, due to the high liquid metal velocities there is a high risk of surface turbulent flow and air entrainment within the liquid metal. The combination of interacting flow-thermal-solidification phenomena and associated defects is a challenging modeling task which the authors have previously described and validated. Capturing the metal-air interface, on what are inevitably complex three dimensional geometries, results in highly computationally expensive simulations and simulating a single cast can take weeks on a single processor. This contribution reports on modeling a complex centrifugal cast, gas entrainment, bubble transport and solidification, employing meshes of up to a million elements and investigates the scalability of the model on high performance clusters.Introduction The ultimate goal of any casting procedure is to produce a defect-free product. For difficult to cast alloys, such as Titanium, centrifugal casting has a number of advantage over conventional gravity methods [1]. In the casting of thin sections, such as turbine blades, the metal is forced into the thin sections under centrifugal forces. The centrifugal force can overcome the backpressure due to surface tension and the metal can fill mould sections with thicknesses substantially less than a millimeter. However, the materials used in these castings [2] tend to be highly reactive and requires low superheat. High liquid metal velocity gives rise to a high risk of free surface turbulent flow and of associated entrainment through free surface turbulence [3] and trapping of gas present in the flow [1]."

Jan 1, 2012

By Roberto Javier Santiago

The main properties of Calcium Carbide seem to be the grain size and the CaC2 content. This paper tries to describe the Calcium Carbide used in the South-American steel plants and how and where it is added.

Jan 1, 2006

By Florian Kongoli

While calcium ferrite slags have been successfully used in continuous copper converting for the last 30 years, ferrous calcium silicate slag was proposed about 8 years ago as an additional alternative for copper smelting. Although both slags are normal extensions of each other their phase relations have not been completely clarified. In this paper the liquidus relations of both slags have been quantified at various areas that cover both of them. The existing experimental data have been first reviewed and discussed in relation to the solidification procedure. An original physical model is then used to predict various diagrams of the liquidus surface of both slags. It is shown that the ternary liquidus diagrams normally used for FeOx-SiO2-CaO system are not suitable for industrial slags. The new model diagrams of Fe/CaO versus SiO2 and Fe/SiO2 versus CaO as well as Fe/CaO versus Temperature and Fe/SiO2 versus temperature are proven to be much more convenient for ferrite and ferrous calcium silicate slags. Based on these diagrams the effect of SiO2 and CaO on the melting temperature is quantified. The effect of Cu2O is also quantified through the model. Some Fe/CaO versus Cu2O and Fe/SiO2versus CaO at various copper contents are predicted and the results show good agreement with the experimental data. It is also shown that in the presence of liquid copper, Cu2O is dissolved in the slag depending on the oxidation degree of the system and might lower the liquidus temperature. Some discussions are also presented taking into account plant observations and important conclusions are drawn for copper smelting and converting

Jan 1, 2006

By Aly M. Abdel-Rehim

The present work deals with a study of the mechanical activation of processing of Egyptian monazite by its simultaneous ball-milling and pressure leaching in order to improve the recovery of thorium and lanthanides from monazite. Experiments of simultaneous ball-milling and alkaline leaching of monazite contrary to autoclave leaching were carried out in stainless steel ball-mills of cylindrical shape under different conditions of temperature, pressure, time and alkali amount and strength. The ball-mills were heated and mechanically rotated in an electric furnace by means of roll mechanism. The effective rotation speed was fixed at 130 rpm in all tests. The charge of steel balls of different diameters was equivalent to 45% of the total mill volume. Monazite was charged in ball-mill without preliminary grinding. It is found that high rate of monazite leaching by ball-milling leaching method is achieved at lower temperature, shorter time and lower expense of alkali than in autoclaves. The results obtained show that complete recovery of thorium and lanthanides from monazite (99.8%) by simultaneous ball milling and alkaline leaching is attained at 140°C within 2 h. It is concluded that processing of monazite by its simultaneous ball-milling and leaching is mechanically activated and accelerated as a result of grinding action of steel balls that caused the continuous removal of the hydroxide product from reacting particle surfaces. This leads to the exposing of fresh and activated monazite particles surfaces to alkali leach solution and consequently the acceleration of the reaction of monazite processing.

Jan 1, 2006

By M. Sadayappan

The grain refinement characteristics of four low-lead and lead-free copper base alloys for plumbing applications were investigated. These are leaded yellow brass (C85800). SeBiLOY III (C89550), silicon brasses (C87500 & C87800) and silicon bronzes (C87600 & C87610); Boron and zirconium were found to be the most effective .grain refiners for copper .alloys produced using the permanent mold cast processes. The study indicates that the type of grain refiner to be used is dependent on the alloy type, alloying constituents and their content. After grain refinement, hot tearing resistance of the alloys was improved but mechanical properties remained unaffected. Alloys refined with boron are prone to the formation of hard spots, which will have adverse effect on the surface quality of the castings during polishing and buffing.

Jan 1, 1999

Over the years, numerous hydrometallurgical processes have been proposed as an alternative or complement to smelters for the treatment of copper concentrates. Most of these initiatives met with limited success. Bioleaching is applied commercially for secondary copper minerals heaps and dumps, and bacterial leaching processes are being developed for copper concentrates, although industrial application is still years away. More recently developed processes usually include pressure leaching and/or ultrafine grinding. This paper proposes a new leach process to treat copper sulphide ores or concentrates: the process operates under atmospheric pressure and uses limited concentrations of ferric sulphate as oxidant; the key to the process is the regeneration of the ferric ion, which can be effected in-situ (direct process) or ex-situ (indirect process) using SO2/O2. Examples are presented for the treatment of copper concentrates by agitation leach and of copper ores by heap leaching. Application of the process to copper gold ores and chalcopyrite concentrates is also discussed.

Jan 1, 1999

By Z. S. Wronski

In rapidly solidified Fe-Nd-B permanent magnet alloys, the content and distribution of Nd-rich intermetallic and Fe-phases determine coercivity Hc and remanence Br. Consequently, microstructure plays a crucial role in deter- mining the (BH) max-product of permanent magnets fabricated from these alloys. A study has been initiated to investigate changes in microstructure and the effects on magnetic properties as the material is processed from arc-melted ingot to melt-spun flakes and finally to a product consolidated by hot-forming. Anisotropic magnetization behaviour has been observed in rapidly solidified flakes after low-temperature annealing.

Jan 1, 1989

By M. Huang

A conductivity-based sensor for on-line measurement of free acid was recently built. This sensor is suitable for high ionic strength solutions and its corrosion-free operation is based on induction currents. It has been tested against literature data and measurements made using a previous developed contact-type conductivity cell, with an average difference within 1%. The electrical conductivities of H2SO4?H2O, H2SO4?MgSO4?H2O and NaCl?Laterite-H2Osolutions at temperatures up to 250 °C were discussed. It was found that the solution conductivity depends on various factors, such as the electrolyte concentrations, the type of electrolytes, temperature and the amount of dispersions. A semi-empirical model was developed to account for all the factors discussed. This model was further tested on actual process solutions from the hydrometallurgy of nickel where sulphuric acid solutions containing a variety of metal sulphates and solids. The average difference between the estimated acid concentration from this model and the one from titration was generally less than 5%, which is excellent for industrial applications.

Jan 1, 2006

By V. T. Taniguchi

A process for large scale chromatographic separations using a continuous chromatography technique is described. The process combines the advantages of large scale batch fixed column displacement chromatography with conventional analytical or elution continuous annular chromatography (CAC) to enable large scale displacement chromatography to be performed on a continuous basis (CDC). Such large scale, continuous displacement chromatography separations have not been reported in the literature. The process is demonstrated with the ion exchange separation of a binary lanthanide (Nd/Pr) mixture. The process is, however, applicable to any displacement chromatography separation that can be performed using conventional batch, fixed column chromatography.

Jan 1, 1989

By F. Kongoli

A computerized thermophysicochemical database is being developed for various processes involved in nickel smelting and converting. This database includes optimized models for slag, matte, liquid and solid alloys in the multicomponent system(s) as applied to batch and continuous nickel smelting and converting processes. This database can be used to quantify the multicomponent and multiphase slag/matte/alloy/gas equilibria, liquidus and solidus surface, tie-lines, solubility and/or losses of nickel and other components in the slag, distribution coefficients, components activities, heat and mass balance, etc. The database also includes optimized models for the viscosity of the slags associated with any of the above processes. Both databases are coupled and this constitutes a very effective method to quantify the effect of each component on several parameters of the smelting and converting processes and to diffuse the confusion that exists in the literature. Several application examples have been given to demonstrate the usefulness of this database for quantitative prediction of the thermophysicochemical properties of the phases involved in actual or developing processes, even in the areas where experiments are difficult or impossible. The considerable cost reduction that results ftom the use of this database as compared to other methods in the improvement of existing technologies or in the development of new ones is discussed along with continuing new developments of this database.

Jan 1, 2002

By Daniel Kim, Ari Rantala

Efficient on-line monitoring of electrolytic cell performance in copper electro-refining has been challenging due to the need for complex electrical measurement systems and the management of the enormous volume of data. Based on Kennecott Utah Copper's innovation Outotec has developed a novel and innovative electrolytic cell monitoring system called CellSense™ System. As the system is based on self-powering from bus bars, wireless communication, on-line adaptive modeling and easy to access information and alarming, traditional obstacles of electrolytic cell monitoring are eliminated. With cell voltage and electrolyte temperature measurements, CellSense System enables real-time cell performance discovery and early reaction to critical production or quality disturbances such as short-circuiting, flow blockages, cold cathodes or electrolyte temperature excursions. During the past few years the system has been delivered to over 3500 commercial cells. In this paper the largest CellSense™ System ever delivered and recently adapted by Kennecott Utah Copper with 1412 cells monitored on-line for high tankhouse performance, cathode quality and optimized operator work flow is presented. Early results and benefits are discussed.

Jan 1, 2012

By C. M. Acuna

Scarcity of high grade copper low impurity content ores is a reality and processing of low grade dirty concentrates is a need. In spite of this fact, innovative strategies have to be looked at to comply with day to day more stringent environmental regulations. From this perspective the production of matte grades over 70% in copper presents several merits, but it must be contrasted with the fractional distribution of impurities reporting to the condensed phases. Converting of white metal high in arsenic content results in moderate fraction of arsenic to gas, but high deportment to blister. Therefore, production of anode copper, as required by the electrolytic refinery, may result in several operational difficulties. Furthermore, by recycling the flue dust and slag produced in the smelting-fire refining cycle, the arsenic content in the feed to smelting increases and so does in the resulting anode copper. The Teniente Converter, as a smelting unity, has probed suitable for production of high matte grade near white metal composition but regarding distribution behaviour of impurities there is lack of reliable data, specially when processing concentrates over 1% in arsenic content. In the new scenario, i.e. low grade copper high arsenic content concentrates, to fully asses the merits of this technology the effect of matte grade, secondary materials recycling and arsenic in feed upon the distribution coefficient of arsenic between slag and matte, mainly, must be evaluated both from a theoretical approach and by use of industrial data. Based on available data correlations of distribution coefficient, matte grade and matte/slag ratios with arsenic in feed and copper content in slag are worked out. Based on these results suggestions as to matte grades facilitating to deal more efficiently with the handling of smelting byproducts are proposed.

Jan 1, 2006

By V. A. Bryukvin

A characteristic feature of the macrokinetics of the interaction process is the presence of two specifically defined areas of oxidation which had a linear time dependence. The effect of variables, such as residual sulphur content of the melt, temperature and the oxidation potential of the gas phase, on the macrokinetics of oxidation are investigated. Phase composition and structure of products of solidification of partially oxidised melts and thermodynamic properties pentaining to Cu-S-O melts are used to analyze the macrokinetic behaviour and mechanisms of the interaction. The process of interaction of sulfide copper melts with oxygen may be considered as a disproportional absorption process and its mechanism is based on localized interaction on the surface and inside the melt volume. Superficial processes include also the process of primary chemisorption of oxygen by melts at place of metal-metal donor bonds proceeding with formation of oxysulfide liquid solutions and volumetric decomposition of the latter accompanied by evolution of sulfur dioxide and metallization of sulfide melts. It is the degree of dynamic balance of such interaction processes that determines specific individual features of the macro-kinetics and mechanism of oxidation of sulfide copper solutions with oxygen in the gas phase.

Jan 1, 2006

By Peter Forschner

Classical Mixing Theory is based on applying many fundamental correlations to standard baffled dished bottomed vertical cylindrical vessels with high degrees of symmetry. Horizontal autoclaves operating at elevated temperatures and pressures have been used for more than two decades. All compartments and especially the first and last compartments are asymmetrical. To date no comparison of the effects of the asymmetric geometry on mixing system design and scale-up has been published. The results of investigating solids suspension, mixing time, momentum transfer from the impeller to feed slurry and feed inlet location in the first autoclave compartment are presented as influences on residence time distribution. CFD modeling was developed and verified with the test apparatus.

Jan 1, 2003

By Brian Lightfoot

Ausmelt Technology uses a furnace/slag/lance system in a way analogous to the way a chemical engineer would use a mixed reactor. The technology is sufficiently versatile to treat materials under a very wide range of temperature and chemical conditions. At one extreme the system has been operated at temperatures high enough and oxygen potentials low enough to make iron. At the other extreme it has been operated of temperatures as low as 800°C and oxygen potentials high enough to cupel lead from silver. This versatility permits the treatment of a great variety of wastes including asbestos, mixed organic\heavy metal wastes, incinerator ash smelter residues, waste water treatment sludges, organochlorine compounds and many others.

Jan 1, 1994

By Steven Wright

BHP Billiton?s Olympic Dam copper flash smelter employs the direct to blister process for smelting high grade copper concentrates. SO2 evolution during tapping gives rise to safety concerns. A thermodynamic model for the blister copper (Cu-Fe-S-O) was used to predict the volumes of SO2 evolved. The Multiple Phase Equilibria Model (MPE) was used to evaluate the slag chemistry inside the furnace. The blister copper model was used to explore the relationship between %S and %O in the copper and the amount of SO2 evolved on cooling. The volume of SO2 evolved was sensitive to the O content with reduction to levels below 0.2 ? 0.15% likely to suppress SO2evolution on cooling. Concentrations of S and O in copper samples from trials generally lay above the equilibrium line calculated for an average temperature of 1275C and a partial pressure of SO2 of 1 atm. Consequently there is a thermodynamic driving force for SO2evolution when cooling to this temperature during tapping. A number of potential process options to suppress SO2 evolution on tapping were investigated thermodynamically. Some of the options require treatment of the blister in a forehearth or separate furnace, while others impact on current practises in the flash furnace with slag present. The opportunities that these options present are discussed.

Jan 1, 2006