Mechanism of explaining liquid friction and flux consumption during non‐sinusoidal oscillation in slab continuous casting mould

Abstract

The mechanism of explaining liquid friction and flux consumption in a non‐sinusoidal oscillation mould is expounded by proposing a series of indices for estimating interface phenomena between mould and metal in meniscus and calculating the effect of non‐sinusoidal oscillation parameters on these indices. The results show that the liquid flux is periodically infiltrated into the gap between oscillating mould and withdrawing slab by the negative pressure caused by widening flux channel from the last stage of positive strip time to the last stage of negative strip time. The surface cracks on the slab, even breakout, are formed during the positive strip time and existing surface cracks can be healed within the cumulative negative strip time. The casting performances were improved by decreasing oscillation frequency and increasing amplitude and non‐sinusoidal oscillation factor.

On explique la friction liquide et la consommation de flux dans une coquille à oscillation non‐sinusoïdale en proposant une série d’indices pour estimer les phénomènes d’interface entre la coquille et le métal dans le ménisque et pour calculer l’effet des paramètres d’oscillation non‐sinusoïdale sur ces indices. Les résultats montrent que le flux liquide s’infiltre périodiquement dans l’espace entre la coquille oscillante et la brame en retrait par la pression négative causée par l’élargissement du canal de flux à partir de la dernière étape de temps positif de démoulage jusqu’à la dernière étape de temps négatif de démoulage. Les fissures de surface de la brame, et même la percée, sont formées lors du temps positif de démoulage et les fissures de surface existantes peuvent être réparées lors du temps négatif cumulatif de démoulage. Le rendement du moulage s’améliorait en diminuant la fréquence d’oscillation et en augmentant l’amplitude et le facteur d’oscillation non‐sinusoïdale.     

Guide for Authors

The Journal of Rare Earths published monthly is a unique international scientific journal which publishes original high-quality works on various aspects of basic theory and applied science in the field of rare earths.The journal accepts contributions from authors both in China and abroad.Therefore,it provides an international platform for the researchers and experts who are engaged or interested in the research of rare earths and related disciplines.The Journal o f Rare Earths publishes original research articles,reviews,and communications which reflect the latest progresses in the fields of RE chemistry&hydrometallurgy,RE metallography&pyrometallurgy,RE new materials,RE solid state physics&solid state chemistry,RE analysis,RE geology&ore dressing,etc.     

Guide for Authors

The Journal of Rare Earths published monthly is a unique international scientific journal which publishes original high-quality works on various aspects of basic theory and applied science in the field of rare earths.The journal accepts contributions from authors both in China and abroad.Therefore,it provides an international platform for the researchers and experts who are engaged or interested in the research of rare earths and related disciplines.     

Growing demand for zinc

China's zinc consumption is estimated to havegrown by 8.2 per cent year-on-year reaching1.3 million tons in 2000,according to an analy-sis report.The galvanizing industry is still the main con-sumer for zinc and the growth rate in this areais most apparent.In 1999 for example,the do-     

Export quotas for zinc

Moftec has already decided on the export quo-tas of zinc and zinc concentrates in 2001. Ac-cording a report,this year's export quotas forzinc ingots and zinc concentrates will be525,000 tons and 65,000 tons respectively.Over half of the export quotas will be given tothe major producers.     

Approaches for Making Risk-Based Go∕No-Go Decision for International Projects

The world economy is becoming more global due to agreements such as the “Uruguay Round” in the General Agreement on Tariffs and Trade. The globalization of the construction industry provides tremendous opportunities for contractors to expand into new foreign markets. However, international construction involves all of the uncertainties common to domestic construction projects as well as risks specific to international transactions. Consequently, in opposition to the worldwide globalization trend, only 19% of the U.S. top 400 contractors actively seek international contracts. This paper discusses current approaches related to entry decisions into international construction markets. It then develops a comprehensive approach for making stable and systematic go∕no-go decisions for international projects. Finally, a pilot study is used to demonstrate and validate the approach.     

Provider profiling: What works for medicine works for mental health?

Provider profiling is a growing practice in organizations that supply or pay for health care, and escalating health care costs are likely to accelerate this trend. First developed for general medical settings, profiling systems now challenge practicing psychologists to meet ostensibly objective, scientific standards of care. The most advanced approaches compare providers on a "level playing field" statistically adjusted for variations in the "illness burden" of their patients. Profiling psychological practice, however, requires specialized new tools and more sophisticated analytical methods than have typically been used. This article provides a practical overview of provider profiling, emphasizing related developments in health care policy that are perhaps less familiar to practicing psychologists. Potential pitfalls confronting professional psychology are discussed, and points for advocacy are suggested. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Call for Papers for the Special Issue on“Electroslag Metallurgy”

Electroslag metallurgy plays an important role in the field of high-quality special alloys and the materials used for high-end equipment manufacturing such as rotor steel,bearing steel,die steel,and superalloy.Moreover,electroslag metallurgy technology has been extended to the field of resource recovery.     

Friction Model for Strip Rolling

To improve the accuracy and speed of finite element calculation,a new friction model was proposed,in which a layer of thin friction element between the roller and workpiece was introduced to consider the contact friction.This model was used in the three-dimensional elastic-plastic finite element model of strip rolling process.Taking the geometrical size and physical characteristics of intermediate medium between roller and workpiece into consideration,the stiffness of the friction element was corrected by two factors,i.e.,the thickness of friction element and β factor.Without any assumption about the value and direction of friction force and neutral point position,the rolling process was simulated by using this model.The results obtained by this model were compared with the experimental results and the feasibility of the model was verified.     

Export tax adjustments for 2000

According to the newly published Importand Export Trade Regulations by the Min-istry of Foreign Trade and Economic Coop-eration (Moftec),the export tox for leadand zinc concentrates is adiusted from theprevious 30 per cent for both to 5 percent and 10 per cent respectively.Export     

Effect of SiO2 substitution with Al2O3 during high-Al TRIP steel casting on crystallization and structure of low-basicity CaO–SiO2-based mold flux

The crystallization and structure of non-conventional lime-silica-based mold fluxes after undergoing slag-steel interaction in casting high-AI transformation induced plasticity(TRIP)steel were studied.The results showed that the crystallization temperatures of the mold fluxes decreased with decreasing the SiO2/Al2O3 ratio,and CaO/MnO2 ratio had an opposite effect on the crystallization temperatures.The crystalline phases precipitated in the mold flux were Ca4Si2O7F2 and NaAlSiO4.Decreasing SiO2/Al2O3 ratio and increasing CaO/MnO2 ratio in the mold fluxes have no influence on the types of crystalline phases.The dominant crystalline phase precipitated in each mold flux was Ca4Si2O7F2 with dendritic morphology,except for part of that with globular morphology in the mold flux without MnO2 addition.NaAlSiO4 crystals are distributed in the space among Ca4Si2O7F2 crystals.The size of Ca4Si2O7F2 crystals in the slag with higher S1O2/AI2O3 ratio is smaller,which is attributed to the polymerization degree of the mold flux with increasing SiO2/Al2O3 ratio.[SiO4]-tetrahedral,[AlO4]-tetrahedral and T-O-T bending(T denotes Si or Al)depolymerized gradually with decreasing SiO2/Al2O3 ratio,and an opposite trend was observed for the case with increasing CaO/MnO2 ratio.The polymerization degree of the mold fluxes decreased,which would result in the decrease in the viscosity of the mold fluxes.     

New Opportunities for Lanthanide Luminescence

Trivalent lanthanide ions display fascinating optical properties. The discovery of the corresponding elements and their first industrial uses were intimately linked to their optical properties. This relationship has been kept alive until today when many high-technology applications of lanthanide-containing materials such as energy-saving lighting devices, displays, optical fibers and amplifiers, lasers, responsive luminescent stains for biomedical analyses and in cellulo sensing and imaging, heavily rely on the brilliant and pure-color emission of lanthanide ions. In this review we first outlined the basics of lanthanide luminescence with emphasis on f-f transitions, the sensitization mechanisms, and the assessment of the luminescence efficiency of lanthanide-containing emissive molecular edifices. Emphasis was then put on two fast developing aspects of lanthanide luminescence: materials for telecommunications and light emitting diodes, and biomedical imaging and sensing. Recent advances in NIR-emitting materials for plastic amplifiers and waveguides were described, together with the main solutions brought by researchers to minimize non-radiative deactivation of excited states. The demonstration in 1999 that erbium tris(8-hydroxyquinolinate) displayed a bright green emission suitable for organic light emitting diodes (OLEDs) was followed by realizing that in OLEDs, 25% of the excitation energy leads to singlet states and 75% to triplet states. Since lanthanide ions are good triplet quenchers, they now also play a key role in the development of these lighting devices. Luminescence analyses of biological molecules are among the most sensitive analytical techniques known. The long lifetime of the lanthanide excited states allows time-resolved spectroscopy to be used, suppressing the sample autofluorescence and reaching very low detection limits. Not only visible lanthanide sensors are now ubiquitously provided in medical diagnosis and in cell imaging, but the feasibility of using NIR emission of ions such as YbⅢ is now being tested because of deeper penetration in biological tissues.     

Routine antibiotic cover for newborns intubated for aspirating meconium: is it necessary?

A retrospective analysis was performed on 215 babies to evaluate the incidence of septicemia in babies intubated at birth for aspirating meconium from the trachea. Only term, appropriate for gestational age babies were included. Babies with any known perinatal risk factor for infection were excluded from the study and none of the babies had been put on "prophylactic antibiotics." There were 88 babies in the intubated group in a one year period from January 1991 to December 1991. One hundred and twenty seven babies were taken as controls. There was no significant difference in the incidence of early septicemia in the two groups. There were no deaths in either group. It is concluded that well term babies who are intubated for aspirating meconium need not be put on routine antibiotic cover.     

Optimization of Mold Oscillation for High Speed Casting — New Criteria for Mold Oscillation

Abstract

Consistent and uniform lubrication in the mold during casting is an issue especially with high speed casting. However, criteria of mold oscillation related to lubrication, has not been clarified for critical conditions such as thin slab casting. This paper discusses the mechanism of powder penetration into the meniscus, in terms of negative strip area ratio and positive strip time, including the case of non-sinusoidal oscillation which is effective for better mold lubrication. In this context, a lubrication index is proposed as a new criteria which can be used to estimate mold powder consumption rate. © 2000 Canadian Institute of Mining and Metallurgy. Published by Elsevier Science Ltd. All rights reserved.

Résumé

La lubrification consistante et uniforme du moule lors de la coulée est un sujet important, spécialement pour la coulée à haute vitesse. Cependant, les critéres d'oscillation du moule reliés à la lubrification n'ont pas été clarifiés pour des conditions critiques telles que la oulée de brame mince. Ce document discute du mécanisme de pénétration de poudre dans le ménisque, en termes de rapport négatif de surface d'écoulement et de durée positive d'écoulement, incluant le cas d'oscillation non sinusoïdale, plus efficace pour la lubrification du moule. Dans ce contexte, on propose un index de lubrification comme nouveau critére pouvant être utilisé dans l'estimation du taux de consommation de poudre du moule. © 2000 Canadian Institute of Mining and Metallurgy. Published by Elsevier Science Ltd. All rights reserved.     

BioMinE – Integrated project for the development of biotechnology for metal-bearing materials in Europe

Biohydrometallurgy is the offspring of the unexpected union of biotechnology and metallurgy. From specific properties of some extreme biotopes, active principles of interactions between microbial metabolisms and minerals have been extracted to be used as efficient metallurgical processes.Many profitable industrial operations based on these bioprocesses have been running to recover copper, gold, uranium or cobalt for instance and many other applications have been designed.Europe was quite active in this area in the past, but currently the leadership is in South Africa, America and Australia.BioMinE (Biotechnology for Metal-bearing material In Europe) is a large integrated project launched with the support of the European Commission. It is aimed at stimulating synergies between the most relevant universities, research and industrial organisations to develop new concepts in this technical field that allow a better exploitation of the mineral resources in the future.The main technical subject is the investigation of the opportunities to apply bioleach processes to primary and secondary resources of metal-bearing materials. The second technical area of the project in terms of effort is the study of the recovery of metals from pregnant bioleach solution using biological reagents. All along the project duration, these investigations are focussed on the relevant resources in Europe screened according to an iterative process. The integration of the innovative pathways of processing will be evaluated up to the pilot scale whenever it is appropriate.The Consortium of BioMinE comprises 35 partners from industry (12 including 5 SMEs) research organisations (9) universities (14) and government (2). The participants are from 12 EU member states, from 1 candidate country (Romania), and from South Africa (INCO Country).The overall budget of the project is 17.9 million Euros, with a contribution from the European Commission of 11.6 million Euros. Started on November 1, 2004, the project will last 4 years.An overview of BioMinE in the general context of the biohydrometallurgy development is the subject of this presentation.     

Our ancestral physiological phenotype: an adaptation for hypoxia tolerance and for endurance performance?

There are well known mechanistic similarities in human physiology between adaptations for endurance performance and hypoxia tolerance. By using background principles arising from recent studies of the evolution of the diving response in marine mammals, here we analyze human responses to hypobaric hypoxia based on studies with several different low and high altitude human lineages. As in the evolution of the diving response in pinnipeds, we found "conservative" and "adaptable" physiological characters involved in human responses to hypoxia. Because the analysis concerns traits within a single species, conservative characters dominate the picture (they define basic human physiology and largely are independent of environmental parameters). Most notably, we also found evidence for adaptable characters forming the foundations for a fairly unique physiological phenotype-a low capacity version favored under hypobaric hypoxia and a high capacity one favored for endurance performance. Because current evidence implies that the human species arose under conditions that were getting colder, drier, and higher (situations in which these traits would have been advantageous), we hypothesize that this physiology is our "ancestral" condition.     

China''''s Lead Market Outlook for 2003

Production of lead concentrates and refinedlead will increase synchronously in 2003.Afterthe Nandan event,which took place in Guangxiprovince in July 2001,China has waged alarge-scale campaign to rectify small mines.Bythe second half of 2002,the rectificationcampaign of small mines have completed insuccession,and the price rise of leadconcentrates has greatly stimulated thereopening of the lead and zinc mines thatqualify for the reopening conditions.The minesin the Nandan region of Guangxi Province haveentered a restructuring period with the