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By Oleksandr Liaskovskiy, Sergey Beringov, Sergiy Yatsuk, Timur Vlasenko, Iryna Buchovska

"Working with solar-grade silicon for solar cells application usually meets some difficulties in comparison to polysilicon produced by Siemens method: higher impurities content leads to lower yield, worse electro-physical parameters and poor performance in solar cells application. However some adjustments in ingot production can show significant improvements in quality of final product: crystalline wafers and cells.Recent investigations have shown that solar-grade silicon is suitable for high effective production process such as mono-like multicrystalline wafer production. Production-scale lots made at Pillar show promising results for solar-grade silicon application: high-quality wafers with significantly big crystalline grains of <100> orientation.IntroductionThe standard technology of producing multicrystalline silicon ingots by directional solidification method in quartz crucibles has a number of disadvantages resulting in limited efficiency of solar cells made of multicrystalline material: crystallites of multicrystalline ingot are relatively small (down to 5 mm size), grain borders of crystallites contain parasitic impurities such as metals, silicon nitride etc., crystallographic orientation of crystallites is random. The listed deficiencies are an integral characteristic of the technology which affects the efficiency of solar cells, such as presence of solar cells with low efficiency even at a high level of average efficiency, problems with shunted cells, silicon nitride inclusions, which adversely affect cell efficiency and are centres for silicon carbide formation, impossibility of application of high effective alkaline texturing etc. Also with regard to the targets set by photovoltaic to reduce the cost per Wp in the nearest future, standard technology of multicrystalline silicon ingots production by directional solidification faces certain challenges some of which are hard to overcome due to rather low efficiency of solar cells made of multicrystalline wafers. Therefore alternative methods of multicrystalline silicon production for photovoltaic application having a number of advantages in comparison to traditional technology are developing rapidly."

Jan 1, 2012

By Sung Jin Han

Magnesia-based refractory is generally used in an electric arc furnace (EAF) due to its relatively high corrosion resistance and strength at high temperatures. However, the magnesia refractory is attacked by EAF slag and thus the lining life continuously decreases. Thus, it is significant to identify the interfacial reaction between magnesia refractory and FeO-rich EAF slags. In the present study, the influence of FeO-rich slag on the corrosion behavior of MgO refractory was evaluated. The (Fe,Mg)Oss layer was observed at the slag-refractory interface and its thickness increased with increasing content of FeO in the slag. The specific reaction phenomena and formation behavior of (Fe,Mg)Oss layer were evaluated by thermochemical computing program, FactsageTM7.0.

By Thomas Havlik

It is proposed to realise the direct leaching, during which will be generated elemental sulfur and not sulfate or sulfuric acid as end product, under conditions that sulfur will not cover the leaching surface and Hot hinder the leaching course. The following improvements have been considered: -use of organic sulfur solvents -ultra high-frequency leaching -ultrasonic leaching -use of surface detergents or surfactants in leaching processes -simultaneously crushing and leaching These proposals are under investigation and preliminary results are promising

Jan 1, 1996

By John Fallavollita

Conventional gas atomization produces powders that vary widely in size distributions and microstructures, thus making it very costly to produce powders tailor made in a narrow size distribution and microstructure. Furthermore, it is difficult to determine the relationships between atomizer operating conditions and resulting powder characteristics. The Impulse Atomization Process (IAP) was developed at the Advanced Materials and Processing Laboratory to produce powders with narrow size distributions. Powders produced by the IAP were reproducible and their sizes could be easily controlled by adjusting experimental conditions. Characteristics of Zn, Sn-Pb, AI-Cu, and Cu powders will be described to illustrate the flexibility of the process to tailor-make powders.

Jan 1, 1994

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 John Wallace, Chib Iheagwara

"Refinements in sensor design have produced low-cost rugged elements to act as loop coupled with stable detection hardware for eddy current measurement in difficult environments. This has allowed direct dimension gauging of nonferrous and ferrous products above the curie point for absolute dimensions and electrical conductivities independently. The software was developed for the analysis of electrical conductivity profiles in CZ silicon crystal growth, then refined for monitoring bar properties and tube properties. Since in most metal working operations, speeds at the minimum of a few hundred feet per minute are encountered the design of the gauge was optimized for a rapid measurement. Independently extracting electrical conductivity provides data in some metal systems for determining the temperature of the monitored product.IntroductionThe primary reason for the use of eddy currents in gauging is that in hostile environments of metal working techniques such as laser gauging and ultrasonics are not always robust enough for in process measurements. Our goal is to use the technique of eddy current measurement as a quantitative control element in various hot and cold processing operations. Inspection in the early stages of metal and semiconductor processing is usually too costly to introduce in a well developed process and these tools are usually only employed in process development. Until recently there has been no efficient general analysis to allow real time measurements in the cylindrical and the probe geometry that could separate dimensional changes from material property changes both which effect the eddy current response. The basis for these measurements is that forward electromagnetic problem for conductors can be solved exactly for the test geometry which allows an inverse analysis to be made by relaxing the dimensions and conductivity to values which reproduce the measured response[!]. This transformation is based on analysis developed in Robert Siegfried' s thesis and was explored both by modeling and by physical measurement. This analysis was extended over the last few years to allow a more compact data set to be used to exact physical properties. The main result was that the technique would work on high ·quality physical data on as little as three test frequencies with the penalty being that the analysis is computational intensive. The main result of this work was that a quantitative inverse analysis of eddy current response would allow a general instrument to be used for a variety of measurements rather than being tailored for a specific measurement on a specific material test geometry. The development of these instruments has progressed over the last ten years for monitoring real time solidification, crystal growth[2] and hot seamless tube forming where the use of standards in traditional eddy current is limiting. The specific instrument design was dictated by the requirements of the algorithm for both frequency selection and levels of systematic noise that could be tolerated. Because the data is need for real time information this dictated that the system be a parallel multifrequency eddy current instrument feeding the same sensor. The sensor have to be simple and robust and usually a single loop or several loop of heat resistant wire or tube. This presentation is about using inversion of multifrequency eddy current data in real time to produce dimensional and property data on cylindrical conductors and planar conductors in real time. The object of the measurements is to produce dimensional outputs on measurements of conducting material without having to establish a detailed standard for each material or size tested. The dimensional measurements using eddy currents is complicated by material variations in conductivity due to temperature and composition. Those variations that are not geometric are often not of critical interest and complicate the measurement. The dimensional changes are often of more importance"

Jan 1, 1997

By Ronald J. Roman

The shrinking core model for coarse particle leaching has been generally accepted as describing the leaching of a copper oxide or sulfide ore. However, when a mixed oxide/sulfide ore-is leached this model can not be used in its simple form because at least two and possibly three separate leaching processes are occurring simultaneously (dissolution of oxide copper minerals, secondary copper minerals and primarily copper minerals). It has been impossible to isolate their individual leaching curves from the recovery/time curve generated by the column leach test. This paper describes a tests program carried out at the Groupo Mexico, Mexicana de Cobre&apos;s La Caridad operation in which the individual recovery/time curves for the leaching of copper oxide mineral, secondary copper mineral and primary copper minerals were developed from standard column leach tests. Once the individual recovery/time curves were developed scale-up of the column leach test results to the commercial heap leaching operation is possible by using the shrinking core model.

Jan 1, 1999

By F. L. Marley

Small and medium-sized flotation plants with no assaying instrumentation still depend much upon the art of the operator to produce acceptable and consistent results. Improved performance can be accomplished by the use of the simple microscope set up as a control device. The visual recognition of products in the circuit does much to eliminate uncertain shift operating decisions and is an easy technique to acquire. Mineral staining methods further assist in the determination of components within the mill products. Simple mounting upon scotch tape and other adhesives is rapid and convenient. The microscope also has a practical role for the plant metallurgist or laboratory technician when evaluating middling products, and their routing within the circuit. Examples are reviewed where the microscope has been used for operational control in both sulfide and nonmetallic mineral flotation plants.

Jan 1, 1981

By D. A. Meyn, R. L. Holtz, C. S. Pande, M. A. Imam, D. J. Singh

"Various theoretical and experimental techniques used to search and develop new metal hydride systems suitable for hydrogen storage are described. The main theoretical technique under study makes the use of electronic structure of the candidate materials. Microstructural characterization techniques like transmission electron microscopy are being used to study the hydride formation. Novel processing techniques for material preparation such as those needed to produce thin films or amorphous phases are also being utilized. The techniques are illustrated with results from Pd, FeTi and Mg2Ni systems.IntroductionOf the four methods of hydrogen storage, compressed gas, cryogenic liquid, metal hydrides, and gas-solid adsorption, the metal hydride storage method is more attractive from the point of view of high volumetric density and safety. Compressed gas storage has disadvantages of extreme pressure, weight, and volume requirements, whereas storage of hydrogen as cryogenic liquid is unattractive due to the requirements of extremely low temperatures and high consumption of primary energy. Moreover, the number hydrogen atoms present in a volume of 10- 22 Cm3 (nH) in liquid hydrogen state (- 20K) is 4.2 whereas number of hydrogen atoms that can be accommodated in a free volume of 10-22 cm3 of various hydrides are as follows: LiH--5.9, TiH2--9.2, ZrH2--9.2, VH2--l0.2. High hydrogen concentration is usually associated with a large H/Metal atomic ratio but is also a function of structure."

Jan 1, 1994

By L. N. Ertzeva

The present work is dedicated to investigation of the sulfidizing process of ore pyrrhotite concentrate with recovery of a sulfide material, enriched with non-ferrous metals, and waste pyrite, with downstream separation by a certain beneficiation method.

Jan 1, 2006

By Cesar O. Gomez

A procedure has been developed for mounting at random particles of mineral samples to be characterized using image analysis. The procedure is based on the generation of a random distribution of sample particles in particles of a diluent material. and the embedding of this particle mixture in an epoxy resin without disturbing the initial distribution. Two materials with atomic number similar to that of the epoxy resin were successfully used as diluents: activated charcoal and graphite. The proportion of diluent material to be mixed with the sample to have a large number of mineral particles in the field of view while keeping the occurrence of touching particles at an acceptable level was determined empirically. The randomization achieved with the procedure developed in this work was tested using as samples known mixtures of silica and pyrite particles of the same sieve class. The agreement obtained between the mass ratio of minerals used in the preparation of a particular specimen and that resulting from image analysis demonstrates that the procedure developed is successful in producing a specimen where the embedded particles are randomly distributed.

Jan 1, 1988

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 Jogre A. S Tenório

he aim of the present investigation was to investigate technological features of the Fe-NbC dissolution in liquid Fe-C alloys. Fe-NbC is a Ferro-niobium alloy with 7%C, has a particle size smaller than 150 pm and its micro constituents are polygonal niobium carbides and an iron matrix. The obtained dissolution time was less than one-minute and the yields were in the range of 80-90% at 1873 K. In the Fe-NbC dissolution process, the dissolution occurs at first, and as a consequence the niobium carbides become free to dissolve. These carbides will dissolve until the melt reaches a saturation point. The non-dissolved carbides remain trapped in the liquid or will form a dross. The addition yields decreases when the niobium concentration reaches this limit value, that depends on the carbon concentration. These define a saturation curve.

Jan 1, 1994

By Itavahn Alves da Silva, Jose Dimas de Arruda, Amanda Aparecida Fátima Arruda, da Silva de Souza, Carlos Antonio da Silva, Varadarajan Seshadri, Samuel

The knowledge of the flow field inside a continuous casting mold is essential to improve operational efficiency of the process and also to achieve better inclusion control. Physical modeling, PIV technique and CFD have been employed to assess the velocity distribution in the metal- slag interface region in a slab mold. The analysis of results shows how higher casting velocity and lower immersion depth of submerged nozzle can lead to higher turbulence in the slag-metal interface. The effects of density difference between slag and metal and interfacial tension between the phases have been highlighted.

Jan 1, 2016

By Michael J. Mankosa

The increased emphasis placed on recycling of consumer and industrial waste products has generated a need for advanced separation techniques for recovery of valuable by-products. As a result, the metals recycling industry has made great strides in the recovery of used wire products through the application of chopping and screening processes. Unfortunately, in many instances, the final plastic reject still contains a substantial portion of valuable metal. Typically, this material has been discarded, since an appropriate separation technique has not been available. Recent work conducted by Carpco, Inc. in Jacksonville, Florida indicates that a high-grade metal and/or plastic product can be recovered from this waste material using a novel density separation process. Extensive test work has been conducted using this procedure to validate separation performance as well as equipment capacity. This paper will present the basic operating principle of the separator, as well as results from tests conducted using various feed materials.

Jan 1, 1995

By Moo Eob Choi

The reduction of iron oxide particles by hydrogen is one of the most widely investigated gas-solid reactions. The search for new methods for producing iron by the direct reduction of iron oxide has resulted in a large number of exhaustive studies of the various aspects of this reaction. However, previous studies have largely been done with either pellets or lump ores. Little has been published on the hydrogen reduction of very fine concentrate particles smaller than 37 µm (-400 mesh). The kinetics of hydrogen reduction of fine iron oxide concentrates were investigated in the temperature range of 900 - 1300°C.

Jan 1, 2006

By Junji Shibata

Through-hole copper plating is performed to make a multi-layer printed circuit board. The through hole plating is first carried out by Pd catalyst treatment, followed by copper non-electric plating. The amount of Pd catalyst used in one plant is about 0.25-2 m3/month (8 g/dm3 PdCl2 base) depending on the plant scale, and the cost of the catalyst reaches 17,000¬I35,000 US$/month. In this study, the flow and material balance of a Pd in Pd catalyst treatment process was investigated. About 60% of Pd catalyst adheres on the through-hole and other part of setup, while 25% is released into the washing liquor. Pd in the washing liquor should be collected by a suitable method like a pressure filtration using diatomite. The material balance of Pd in Pd catalyst treatment process and the recovery method of Pd from waste solution containing Pd catalyst was investigated.

Jan 1, 2003

By Dengfu Chen, Yi Yang, Chunmei Chen, Mujun Long, Shikai Gong, Junhao Sheng, Tao Liu

The relationship between thermo-physical properties of petroleum coke and temperature is of importance for determining of the operating parameters during the calcining graphitization process. In this paper, the variations of thermo-physical properties of petroleum coke versus temperature were investigated, such as the DSC-Tg curve, the specific heat capacity, the thermal diffusion coefficient, the thermal conductivity, and so on. The thermal analysis curve of petroleum coke showed synchronous thermal hysteresis at higher heating rates, indicating that a larger heating rate will cause delay of thermal effects. The thermal diffusivity of petroleum coke decreased during the calcining process. With increasing temperature, coefficient of heat conductivity and specific volume heat of the petroleum coke increased with a decreasing variation rate. The research provides a database for the calcining graphitization process of petroleum coke.

Jan 1, 2015

By Marie-Aline Van Ende, In-ho Jung

A thermodynamic database for the oxyfluoride system CaO-MgO-Al2O3-SiO2-Na2O-K2O-Li2OMnO- FeO-F has been developed based on the critical evaluation and optimization of all available experimental thermodynamic and phase diagram data. The developed database can be used for phase diagram and equilibrium solidification calculations for multicomponent systems and for understanding the solidification behavior of mold fluxes. Based on this thermodynamic database, a simple kinetic model was developed to simulate the interactions between the mold flux and molten steel using effective equilibrium reaction volumes combined with the thermodynamic database.

Jan 1, 2014

By Keizo Uematsu, Kumiko Sanda, Nozomu Uchida

"Full understanding of mechanical properties is the most important assignment in ceramics. Establishment of defects-property relationship is crucial for fulfilling the assignment. This study reports detailed characteristics of defects and their relevance to the mechanical properties for alumina ceramics made through a typical industrial processing. Novel characterization methods were applied to evaluate their defects. A very simple direct correlation was successfully found between defects and properties in ceramics. This result is a great epoch in the field of ceramics. IntroductionThe ceramic materials are used in refractoriness, corrosion resistant materials and structural materials. The low fracture toughness and scatter of strength are very important problems in ceramics. The toughness of ceramics is lower than metal and polymer materials, and the allowed defect size is small. Very small internal defects (pore, crack, huge particle) can be a fracture origin in the brittle fracture. The characteristics of defects such as size, distribution and shape change markedly by process condition, which cause the scatter of strength. This study conducts quantitative evaluation and direct observation of the sizes, shape and a number of internal defects with a light microscope, and discusses the relationship for mechanical properties and defect sizes"

Jan 1, 2000