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By B. J. Beaudry

Intermetallic compounds are frequently required in the form of thin sheets for magnetic refrigeration and other applications. Progress has been made in the preparation of thin sheets of brittle gadolinium intermetallic compounds by hot rolling of sheathed billets. The effect of fabrication procedures on the Curie temperature of GdPd and its heat capacity at low temperatures has been studied.

Jan 1, 1989

By Toshiro Kuji, Masakazu Fujita, Tetsuji Saito

"The magnetic properties of the magnetic materials were deeply dependent on the microstructures. In this study, the novel technique to produce the desired microstructures in a controlled manner was proposed. The technique consisted of the production of the amorphous alloys and the control of the crystallization process. The technique was applied to improve the magnetic properties of Nd-Fe-B permanent magnets. The microstructural control of the magnets exhibited the excellently high energy-products of higher than 430 kJm-1. The relationship between the magnetic properties and the microstructures of the Nd-Fe-B permanent magnets was discussed.IntroductionThe intrinsic properties of the materials are basically determined by the properties of the constituent elements or the compounds. However, it is often noticed the difference between the observed properties and the theoretical values expected from the intrinsic properties of the materials. This indicates that the observed properties of the materials are determined not only by the properties of the constituent elements. In other words, the observed properties of the materials are also strongly dependent on the morphology of materials. This means that the microstructural control may creates a great improvement of the properties of materials.In Nd-Fe-B permanent magnets, the superiority arises from the uniaxial intermetallic Nd2Fe14B compound which has a large saturation magnetization and a high anisotropy field [1,2]. The magnetic properties of the Nd-Fe-B permanent magnets are dependent on the microstructure, that is, the size, shape and degree of the crystallographic alignment of the Nd2Fe14B phase. Currently, the Nd-Fe-B permanent magnets have been produced by either sintering or melt-spinning [3,4]. In the sintered magnets, alignment of the Nd2Fe14B phase is achieved by the prior green compaction of the crushed ingot powders in an applied magnetic field [3]. In the melt-spinning approach, alignment of the Nd2Fe14B phase is achieved by hot deformation [5]. Amorphous melt-spun ribbons are comminuted and then are consolidated into bulk form by hot pressing before hot deformation. As-hot-pressed magnets have randomly oriented Nd2Fe1~ grains [6]. Subsequent die upsetting of as-hot-pressed magnets gives rise to the crystallographic alignment of the Nd2Fe14B phase."

Jan 1, 1998

By Fu-Shen Zhang, Mengjun Chen, Jianxin Zhu

"In China, hazardous e-waste—cathode ray tube (CRT) glass is usually left around, and it is likely to contact with water resources directly. To identify the real leaching characteristics and bioavailabilities of heavy metals Pb and Ba contained in CRT glass in the nature environment, experiments were carried out by simulating the nature environment. The results indicated that Pb and Ba contained in CRT glass were stable in most conditions, which only showed obvious leaching toxicities in strong acidic/alkali conditions. EDTA and DTPA extractable Pb and Ba amounts were extremely high, e.g., EDTA extractable Pb of color funnel glass was up to 1960.07 ìg/kg, indicating that the potential bioavailability of waste CRT glass is very high. IntroductionIn recent years, cathode ray tube (CRT) contained monitors or TV sets has been substituted by novel and better electronic and electric equipments such as LCD and PDP, leaving huge amounts of end-of-life CRTs. 50~85% of the total weight of a computer monitor or a TV set is glass'1-21, which was classified to three categories: black & white glass (BW), color panel glass (CP) and color funnel glass (CF), according to their chemical compositions'3' (Méar et ai, 2006). In order to provide shielding from X-rays generated during the picture projection process, lead, barium and strontium oxides were used in the glass. In general, a color CRT contains 1.6-3.2 kg of lead'4'. Concerning the high toxicity of lead, these waste glasses have posed a potential risk to the environment and human health and researches on these glasses have been attracting wide and tense attention currently."

Jan 1, 2011

By Toshiharu Hayashi

We prepared the water dispersed with Au particles ranging from 10 to 20 nm size by a novel wet chemical synthesis; generating seeds of Au cluster by adding a borane dimethylamine complex into chloroaureic acid (gold salt) solution, and then growing simultaneously with aminoalcohol included in the solution. As-prepared Au nano-particles with chemical surface modification were found to have some attractive performances, i.e., showing a high dispersiveness in an aqueous solution in a long time, sintering nano-particles at low temperature, and having low resistivity in the film prepared from nano-particles. In the case that smaller Au nano-particles were removed from as-prepared colloid, especially, Au thin film formed on the surface of Si plate showed the excellent value of 7.0x10-6ohm cm (reference peculiar resistance: 2.35x10-6 ohm cm).The sintering temperature was dependent on the elimination of 2-aminoethanol that modified on the surface of Au nano-particles.

Jan 1, 2006

Iron(II), sulphur dioxide and sugars such as lactose are potential reducing agents for manganese dioxide to produce manganese(II) for subsequent hydrometallurgical treatment. The leaching of limonitic laterite and manganiferrous ores with sulphur dioxide produces iron(II) which in turn can catalyse the leaching of manganese dioxide in acid media. This paper presents a critical analysis of the kinetics of reductive dissolution of synthetic manganese dioxide and manganese ore to compare and contrast the effect of sulphur dioxide and iron(II) in acid media containing sulphate or perchlorate anions. Both one-electron and two-electron mechanisms are considered in the case of sulphur dioxide. The current knowledge on chemical speciation is used to construct an Eh-pH diagram to show the effect of complexation of Mn(II), Fe(II) and Fe(III) with sulphate. Heterogeneous and electrochemical reaction kinetic models are combined to propose reaction mechanisms which rationalize the dissolution kinetics.

Jan 1, 2003

By G. J. Shiflet

This paper will review work done in our laboratory on the formation, thermodynamics and crystallization of aluminum based metallic glass with the addition of rare earth elements. The results demonstrate that the metallic glasses are truly amorphous and not microcrystalline and that they are unusual in their formation because the alloys contain 90 at. % aluminum and there is no deep eutectic present in the phase diagram. Tensile strengths that exceed 900 MPa are obtained for several of the compositions and exceed 1000 MPa after partial crystallization.

Jan 1, 1992

By P. Mercille, M. F. Nasmyth, J. G. Cooper

The turn of the century sees considerable activity in the zinc industry for the replacement or expansion of existing cellhouses, and the building of new cellhouses as part of new zinc projects. Aside from the cellhouse technology itself, numerous engineering and construction issues play a major role in the success of a project for replacing or building new cellhouses. The purpose of this paper is to bring to light and to address the engineering and construction factors which go beyond the selection of a cellhouse technology and which remain of key importance in implementing such projects. In addition, some implications of these factors for project costs will be illustrated.

Jan 1, 2000

By Nobuaki Sato, Tetsuo Fukasawa, Akira Kirishima

To apply the fluoride volatility process for the treatment of fuel debris formed in the damaged nuclear reactors, study on the fluorination behavior of main constituents, such as fuel and cladding is essential. The mixture of uranium and zirconium oxides is formed under severe conditions such as high temperature and oxidizing atmospheres. In this paper, fluorination and volatilization behavior of uranium and zirconium oxides have been studied by TG-DTA method in the presence of fluorine. From the TG-DTA result of UO2 in F2 atmosphere, the weight gradually increased up to 7% at 350 oC followed by rapid weight decrease with exothermic peak showing the vaporization of uranium as UF6. ZrO2 showed similar fluorination behavior to that of UO2. However, fluorination of UO2-ZrO2 seemed to be suppressed with increasing ZrO2 amount. This may be caused by the formation of solid solution.

Jan 1, 2016

By F. W. Warnaars

Chanarcillo is a historically well-known silver deposit which produced over 100 million ounces. High grade vein-type mineralization is confined to a prominent set of nearly vertical, NNW to NE fractures that intersected limestones, andesites and tuffs of Early Cretaceous age. A significant amount of disseminated silver mineralization extends laterally outward from the fractures for considerable distances in pyritic carbonaceous limestones, whereas more competent volcanic beds rarely contain lateral mineralization. Local exposures of skarns are mostly barren. Silver and minor base metal mineralization was probably formed peripheral to a granodioritic intrusion inferred to exist at shallow depth. Part of this intrusion is exposed nearby where it contains significant hydrothermal mineralization and alteration. This intrusion was dated at 83.8 m.y.

Jan 1, 1987

By M. Benavides

An experimental study is carried out With sulphide ore obtained from Bailadores-Venezuela as well as artificial concentrates. Concentrates of the minerals from froth flotation are fused to study equilibrium between the matte and slag phases. The first part of the work deals with obtaining a concentrate by flotation experiments with collective and selective reagents, with acceptable metallurgical recovery, studying the influence of different parameters in the process. The second part gives the results of the experimental investigation. on thermodynamic equilibrium in smelting which facilitates knowledge of the elemental processes, giving bases for the possibilities of reducing the loss of metal in slag.

Jan 1, 1983

By Habib Saridikmen

In this experimental study the effects of slag composition on the phosphide capacities of the slag as well as on the phosphorus distribution ratios between the slag and metal phases encountered in ferromanganese smelting have been determined at 1500°C under carbon monoxide atmosphere. The distribution results were employed to calculate the phosphide capacities of the SiO2-Al2O3-CaO-MgO-MnO slags in equilibrium with the Mn-Fe-Si-Csatd.metal phase. The classical gas-slag-metal equilibrium-quenching technique was employed using CO gas atmosphere and graphite crucibles to saturate the metal phase with respect to carbon. The phosphorus distribution ratio increased from 0.045 to 0.375 when the slag basicity increased from 0.72 to 1.39. As expected, the distribution ratio decreased from 0.375 to 0.105 when silica increased from 37 % to 45.8% in the slag phase. The phosphide capacity values were calculated by using the results of experiments. Empirical relationships were developed to express the phosphorus distribution ratios and phosphide capacities of the above slags.

Jan 1, 2006

By Cam T. Nhan

The potential use of coal fly ash as a construction material has been recognized for many years,. In this work, an admixture of the ash residue is investigated for use as a landfill liner. In particular, its performance as a chemical barrier to the leachate from the municipal solid waste (MSW,) is determined. The test specimens are a water compacted admixture of class F fly ash, low in calcium content, which is blended with lime dust and calcium bentonite. MSW is passed through the compacted fly ash specimens under a gravitational head. The. diffusion of elements in the leachate through this material is monitored as a function of time. The distribution profiles of the retained elements in the compacted admixture provide prediction of the long term performance of the compacted admixture directly affect the leachate diffusion rate, hence, the mobilities of the retained elements.

Jan 1, 1992

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 Ken-ichi Miyazawa

A Center of Excellence (COE) titled the Creation of Nature-Guided Materials Processing, called Nature COE, has been established at Nagoya University. In the Nature COE, a new field of material research is being developed through learning the laws of nature, namely, methods of attaining ?appearance of the maximum function under the minimum substance and energy consumption?, which the nature and living organisms have acquired through their evolution in long period. As one of the specific features, an ?Open Cluster Program? was originated for promoting the researches conducted by young researchers and Ph.D. students with those in and out of the university and also for fostering them, together with such educational programs for Ph.D. students as the research incentive, the oversea training and the international lodging seminar programs. The Open Cluster Program has been found to be effective for fostering of young researchers and students, for promoting their researches, for gathering researchers and knowledge from the world and for propagating the research fruits. Through conducting these programs, world-highest intelligent fruits and a gathering of young minds to lead the new field are expected. In this COE, the researches are conducted on (1) materials used for living bodies, (2) mimicking structures which nature or living bodies are forming and (3) materials processing by mimicking processes to form the structures observed in the nature or the living bodies. These researches are conducted by four groups to extend the processes observed in the natural world to a new type of processing that is thoroughly rationalized by plunging a scalpel of engineering, and to establish a new academic field of materials science and engineering.

Jan 1, 2006

By Yuan Zeping

The distributions of impurities in the copper melt, the slag and the gas phase in copper flash smelting process were under study in the Guixi smelter, particularly during operating conditions of high oxygen enrichment with production of high grade matte. Several methods for the removal of impurities such as As, Sb and Bi in the copper smelting process were developed and implemented at the Guixi smelter. This paper described the effects of high oxygen enrichment, elevated matte grade, high temperature and high production rate on the distribution of impurities, methods adopted at the smelter for the removal of impurities, and the associated benefits in the utilization of these removal techniques which include the mathematical model for material blending, high thermal intensity operation at the flash furnace, extended converter blowing, and injection of slag modifiers consisting of Na2CO3 and CaO powder mixture to the converters and anode furnaces.

Jan 1, 1999

By Dirce H. Jacomo, Jaciele G. Teixeira, Anibal Y. Abreu Castillo, EsperidianaA. B. Moura, Yalquiria A. Silva, Rene R. Oliveira, Michelle G. Gomes

"Composites consisting of poly(vinyl alcohol), starch and sugarcane bagasse ashes, using glycerol as plasticizer agent, were prepared by solution casting method. Composites prepared were subjected to electron-beam radiation treatments, at radiation dose of 50 and 80 kGy using a Dynamitron electron beam accelerator, at room temperature in the presence of air. The composite samples obtained were evaluated for their water absorption, mechanical and morphological properties.1. IntroductionThe potential of biodegradable polymers and more specifically of biocomposites obtained from agro-resources have long been well established [1-3]. Starch, derivate from variety of botanical sources (cereals, legumes, and tubers) is widely available raw material and one of the most studied and promising agro-resources for the production of biodegradable polymers as matrices for biocomposite applications. However, starch itself is very brittle, hydrophilic and its mechanical properties are very poor for many applications [3 - 5]. The blending of starch with conventional polymers is a promising approach to improve its drawbacks. Recently, many efforts have been made to blend starch with biodegradable synthetic polymers [5, 6]. Polyvinyl alcohol (PYA) is a particularly well-suited synthetic polymer for the formulation of blends with natural polymers, as it is highly polar and can also be manipulated in water solutions, and depending upon its grade, in functional organic solvents as well [3, 7]. PY A has been reported to be an option to blend with starch. Most of the starch/PY A composites have been prepared by casting. However, it is well known that starch/PY A composites has poor in water resistance and mechanical properties after absorbing water [3,8]. Attempts to improve the mechanical properties and to decrease the water absorption property of the starch/PY A composites are made by adding the cross-linkers and plasticizers. Park et al. prepared starch/PY A/citric acid films by the casting method. They also studied the effect of (spell out) citric acid on the mechanical properties and water resistance of composites [9]. Zhai et al. prepared the starch/PY A hydrogels using electron-beam radiation [10]. Different kinds of lignocellulosic fibers have been investigated in blends for formulation of biocomposites."

Jan 1, 2013

By W. H. Jay

Sulphide-containing minerals, particularly iron, lead to acid formation. In turn, the acid generates effluents such as copper acid drainage (AMD). The Berkeley Pit in Butte, Montana, USA and Mt Lyell in Tasmania, Australia, represent just two of many sites throughout the world for which acceptable treatment methods are required. In the gold cyanidation process, the presence of copper creates both a significant cost impediment and a potential environmental hazard. The tailings dam failure at Baia Mare in Romania which led to the release of copper and zinc cyanides created a major environmental disaster. The application of non-toxic water soluble polymers and ion exchange resins to selectively recover copper from AMD solutions, and the in-plant treatment of copper cyanide solutions and slurries to recover copper and recycle cyanide to prevent cyanide entering the tailings impoundment will be discussed. The economics of the various processes will be highlighted.

Jan 1, 2003

By Wolfgang Baum

Remediation work on thermal process dusts and slags has been primarily based on chemical analyses. These data offer little information for the assessment of treatability and reuse potential. In addition, the lack of mineralogical residue characterization has frequently caused time-consuming and inefficient waste management. This paper will outline the cost-effective, and sucessful use of process-oriented mineralogical analyses for treatment and beneficial reuse of various thermal residues. These include a patented process for detoxification of Pb-contaminated bottom ash, the pyrometallurgical treatment of K 061, the reprocessing of lead smelter slag as well as various power plant residues.

Jan 1, 1992

By Jing Zhang, Chenguang Bai, Fusheng Pan

"The microstructure and hot deformation behaviour of an Er-modified Mg-Zn-Ai alloy were evaluated. The results showed that the addition of rare-earth Er changed the morphology of the quasi-continuous grain boundary networked eutectic compound to globular particles. Moreover, a self-strengthening effect was identified for the alloy, which determined its deformation behavior. After hot extrusion, the yield strength and elongation to failure of the Mg-Zn-AI-Re alloy at 200°C were increased by 105% and 120%, respectively, due to an emerged dynamic precipitation strengthening mechanism.IntroductionMagnesium alloys are attracting increasing attention for applications in automobile, electronic devices and hand tools for weight reduction and higher fuel efficiency, because of their lightweight and a high specific strength. However, application of Mg is still very limited. The largest applications are still those non load-bearing castings used at room temperature, such as box case, housing, and covering. One of the main reasons is the inadequate absolute strength both at room temperature and elevated temperatures (> 100°C) of the commercially used AZ, AM series alloys, due to the incoherent interface between the secondary phase y-Mg17AI12 and Mg matrix, as well as the low thermal-stability of the y phase [1]. Besides, the heat-resistant magnesium alloys which contain rare earth (Re) as the main alloying element are very expensive. The other reason is their poor deformability. The key solution is therefore to develop low-cost heat -resistant wrought alloys."

Jan 1, 2012

By N. Lohja

Metallurgical industries are generally big producers of solid residues of various kinds. In contrast with the past where environmental sensibilities were not so elevated and the accumulated mass of these residues were not considerable, these days the solid residues are everywhere scrutinized among others in term of their harmful environmental impact and as possible materials for valuable elements extraction or secondary utilisation. As a case study, the present paper gives an overview of the solid residues discharged by the metallurgical industry in Albania for the last tens of years. The results of two monitoring study on the solid residues of copper, iron and ferrochromium producing industries are also summarized. The first deals with the origin, quantities and chemical composition of these residues and the second one with the impact of harmful ingredients of these residues in the environment. Some methods for the processing of these solid residues are also proposed in order to ensure a clean environment and to make not just possible but also economically viable their secondary utilisation. This work is part of a bigger cooperation project among local institutions and foreign expert companies such as Flogen Technologies Inc and other in various countries that will not only monitor the situation but will also develop appropriate technologies for treatment of these specific residues.

Jan 1, 2006