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By Alan M. Russell

In recent years, several rare earth intermetallic compounds with the B2-type structure have been reported to exhibit high tensile ductility and high KIC fracture toughness at room temperature. These materials retain considerable ductility even at 77K. These are noteworthy findings because most intermetallics possess poor room temperature ductility and low fracture toughness unless one or more special contrivances are applied (e.g., doping with small additions of interstitial elements, offstoichiometric compositions, testing in ultra-dry atmospheres, etc.). This paper summarizes recent findings on rare earth B2 intermetallics. These include the determination of the active slip systems; the strain rate sensitivities; yield strength maxima at elevated temperatures; the search for possible twinning and stress-induced phase transformations; ab initio calculations of their defect energies and the anisotropy of dislocation line tension. Potential applications of these materials and the possibilities that this study may suggest strategies for increasing ductility in other intermetallic compounds are discussed.

Jan 1, 2008

By Fang Wu

The paper designs an extraction flow for the total recovery of nickel and cobalt and removing magnesium simultaneously from the cadthodic materials of the spent hydrogen-nickel and cadmium-nickel batteries. The separation of Co, Ni and Mg though P507 extraction .The extraction equilibrium pH is 4.5~5.0, ßNi/Co is 140~180, and ß Ni/Mg is 20~25; nickel and magnesium are scrubbed in two steps, in which the equilibrium pH of nickel and magnesium scrubbing is controlled at 5.0±0.1 and 4.4±0.1 respectively. The stepwise scrubbing technique is adopted to remove 94.5% of magnesium and to recover 99.45% of nickel and 95.35% of cobalt. During the integrated extraction and precipitation process the total recovery fraction of nickel and cobalt are 99.99% and 99.95%, and the recovery fraction of magnesium is 94.02%.The recovered NiSO4 and CoSO4 solution are enriched and crystallized.

Jan 1, 2009

By M. Yoshida, S. Hanada, T. Takasugi

"A study has been conducted to examine the effect of ternary alloying elements on high temperature deformation of the C15 NbCr2 based intermetallics in Nb-Cr-X (X=V, Mo and W) alloy systems, which have attractive properties as high temperature structural materials. The high temperature deformation of the C15 NbCr2 intermetallics can be improved by two alloying methods. One method is based on geometrical consideration for site occupation and atomic size factor of component elements and additive elements in the single phase C15 lattice; addition of Mo and V can promote dislocation movement without introducing significant hardening. The other method is based on microstructural modification through ternary alloying; moderate addition of these elements results in a variety of duplex microstructure consisting of the C15 phase and bee solid solution without forming any intermediate phases, and can enhance the high temperature deformability. Particularly, alloys with duplex microstructure equilibrating with Cr-rich bee solid solution is shown to exhibit superior deform ability. Also, lattice property of the additive atoms in the C15 structure and phase relation between the C15 structure and the bee solid solution are investigated by OM, XRD, TEM and ALCHEMI observations and then discussed in association with observed mechanical behavior.IntroductionLaves intermetallics with AB2 stoichiometry belong to the largest group in a large number of intermetallics with various kind of crystal structures, and have a variation of the cubic CIS, the hexagonal C14 and the dihexagonal C36 structures, depending on stacking sequence of XYZ type, each of which consists of four interpenetrating atomic layers (1-3). Some of the Laves intermetallics have good functional properties and therefore are considered to be used as, for instance, magnetic materials, magneto-optical materials, hydrogen storage materials and superconducting materials (2). Also, the Laves intermetallics are considered to be good candidate as high temperature structural materials operating at high temperatures and in severe environment because they have high melting point, low density, and potential resistance to corrosion and oxidation. However, the Laves intermetallics are very brittle at low temperatures because they consist of complex crystal structures similar to many other intermetallics."

Jan 1, 1996

By Valerio Viti

In High Pressure Die Casting a molten metal is injected through a thin gate into the cast cavity. High injection pressures and high gate velocities create atomization phenomena which can negatively affect the final quality of the cast. In order to control atomization process it is essential to understand the atomization patterns and the two-phase flowfield that exist at the gate exit. In the present work, 2D numerical simulations of the flow of molten Magnesium through a high aspect-ratio rectangular gate are performed using a water analogue for an open and closed cavity. The numerical simulations made use of VOF-type (Eulerian) physical models and Lagrangian models. Further, a sub-grid scale model was implemented that, in conjunction with VOF-type equations can efficiently predict the general atomization pattern without the need for high-resolution grids. The numerical results were compared to experimental data for validation.

Jan 1, 2006

By He De-wen

The influence of wastewater containing benzene from chemical industry by technology combined blow-off with Fenton reagent oxidation was experimentally studied. The present results suggest that the technology combined blow-off with Fenton reagent oxidation can effectively remove benzene pollutant in wastewater. The main factors that influence the removal benzene such as temperature and blowing time and volume, pH and reagent dosage of H2O2 and Fe2+ are studied and the optimal experimental conditions are as follows: time 20min, temperature 40i, air-blowing volume 0.4L/min, pH value 5, and H2O2 and Fe2+ dosage 2mL/L and 200mg/L respectively. Under the above conditions, benzene pollutant can be removed up to 97%. Compared to other removal ways of wastewater containing benzene, the technology combined blow-off with Fenton reagent oxidation is more effective and has the advantage of high speed.

Jan 1, 2009

By Marco Olper

The Italian company Engitec Impianti has developed a new electrochemical technology for the treatment of Electric Arc Furnace (EAF) flue dust generated in steel mini-mills. This process is based on a new and completely different concept from the Waeltz technology applied at present and allows, due to its modular nature, for an erection on the steel producer's site. Engitec Impianti spent US $700.000 constructing a 500 t/y throughput pilot plant at Pittini Group's Ferriere Nord mini-mill in Osoppo, Italy in order to demonstrate the process capabilities and obtain the data for a commercial plant design. The paper describes the pilot plant performances and the engineering criteria for a commercial unit of 10.000 t/y throughput. The feasibility study demonstrates a pay-back period of 3 - 4 years for the commercial plant.

Jan 1, 1995

By Chidchai Loyprasert, R. A. Stoehr

"A computer model has been developed to predict grain structures in alloys solidified under unidirectional flow using a combination of three techniques -- solution of the equations for flow of an incompressible fluid bounded by curved surfaces by the SOLA-SURF algorithm, calculation of heat flow by a finite difference method, and simulation of grain formation by a two-dimensional cellular automaton (CA) model. The changing rigid surface has been taken into account. Heterogeneous and homogeneous nucleation are considered, and the growth kinetics of a dendrite tip are evaluated by the Kurz-Giovanola-Trivedi (KGT) model. These calculations were applied to solidification of an Al-4.5% Cu alloy flowing over a chill on the bottom of a channel, a system for which experimental results were available. Using a variety of flow rates and superheats, agreement between the computed and experimental results were very good including transitions between columnar and equiaxed grains, the aspect ratio of the grains, and the inclination of the grains to the flow.IntroductionModeling of casting and solidification processes has developed over the years along two distinct tracks: (1.) modeling of macroscopic heat transfer and fluid flow for design purposes, and (2.) modeling of microscopic processes such as nucleation and growth in order to improve the scientific understanding of the phenomena involved. The present work is an attempt to combine the macroscopic and microscopic approaches for the solidification of an alloy flowing over a chill. The specific case chosen is that of an aluminum-4.5 % copper alloy flowing linearly over a water-cooled copper chill for which experimental results were available over a range of flow rates and superheats. For the macroscopic calculations, the SOLA-SURF algorithm for solution of the twodimensional fluid flow equations was combined with the finite difference method (FDM) for calculating heat transfer. For the microscopic calculations, heterogeneous and homogeneous nucleation were considered, and the growth kinetics at the dendrite tips were evaluated. The cellular automaton (CA) technique was used to apply the microscopic kinetics to the temperature and .flow conditions."

Jan 1, 1999

By Chonghe Li, Pengyue Gao, Xionggang Lu, Juyun Kang, Wajid Ali, Guangyao Chen, Ziwei Qin

A refractory U–Mo associated ore containing jordisite which enclose U, Mo component, and impede penetration, diffusion process of leaching, oxidation agent was investigated through three approaches of focusing on U, Mo extraction. The results indicate flotation beneficiation without followed metallurgical process is not appropriate because of high target metals loss rate via water leaching. H2SO4, H2O2 dosage recommended to oxidation leaching are 10 and 6–8% of ore mass, and U, Mo leaching rate are 92.71 and 52.16% respectively. For the acid pressure leaching, U, Mo leaching rate 93.75 and 76.07% are achieved under optimal temperature 130–140 °C and H2O2 dosage 8% combined with pressure air 0.6 MPa. Fluidized bed furnace roasting parameters include air flow rate 0.64 m/s, air ore ratio 0.3 m 3/kg at roasting temperature 550 °C with U, Mo leaching rate 93.2 and 89.5%, so enhanced metallurgical process effectively destroy wrapper and increase metal recovery rate.

Mar 1, 2018

By W. John Rankin

The finite and non-renewable nature of mineral resources poses unique challenges for sustainability: How can mineral and material needs of society be satisfied indefinitely? How can the benefits of exploitation of minerals best be captured for present and future generations? How can the environmental problems caused by large scale mining and processing best be ameliorated? These issues are rarely addressed, or if so only incidentally, in traditional courses in geology, mining, metallurgy and materials yet addressing them will increasingly be a major role for professionals in the minerals and materials industry and related sectors and agencies. This paper describes a framework for examining these and other sustainability issues related to meeting future material needs from non-renewable resources. The framework may be useful for educational purposes, either as the basis of a dedicated subject or by including the elements of it throughout a traditional course in relevant subjects.

Jan 1, 2014

By Torn H. Okabe

A fundamental study was conducted with the purpose of establishing an environmentally sound recovery process for recycling of valuable metals, by combining scraps containing such metals. As an example, direct extraction and recovery of neodymium (Nd) in magnet scraps was investigated by utilizing liquid metal as an extraction medium. It was found that liquid magnesium (Mg) is a suitable extraction medium and can extract Nd from iron alloys with high efficiency at around I 100 K. The newly developed extraction apparatus for Nd is a mechanically simple and static device without moving parts, where the Mg extraction medium circulates due to differences in the temperature inside the reaction vessel. This developed device can simultaneously accomplish continuous extraction of metal Nd from scraps, re-extraction of Mg from Mg-Nd alloy and the eventual recovery of pure Mg. As a result, metal Nd with 98 % purity was directly recovered from magnet scraps under certain conditions. It was also shown that the extraction agent Mg could be reused. The results of this investigation show the possibility of establishing a new process for the direct extraction of Nd in pure metal form without oxidization.

Jan 1, 2003

By Alicia Esther Ares

The family of Zn-Al (ZA), Zn-Ag and Zn-Al-Ag (ZINAG) alloys offers high mechanical properties, ease of finishing, the advantage of low energy and pollution-free melting. Also, present alternatives to the well developed alloy systems, such as brasses, bronzes, cast irons and aluminum alloys. The main objective of this paper is to measure thermal parameters in ZA, Zn-Ag and ZINAG hypoeutectic and hypereutectic alloys directionally solidified which present columnar, equiaxed and columnar to equiaxed transition structures (CET). Also, estimate the mechanical properties, such as microhardness and tensile parameters and correlate these with the thermal (cooling rate) and structural parameters (grain size and dendritic spacing). The different types of structures were analyzed with optical and scanning electron microscopy. The results showed the influence of concentration, microstructural arrangement and thermal conditions during solidification on the mechanical properties. The results of the present investigation are compared with previous experiments.

Jan 1, 2010

By Kiichiro Hayashi

"Indonesia is one of the world leaders in palm oil production. Palm oil industry is an industry to be considered when it comes to environmental impacts. This paper utilizes three step approaches. First, a material flow analysis of palm oil related industry was conducted in Indonesia. Second, a factory visit survey was conducted for getting information on environmental impacts of plantation and CPO mills. Third, a LCA study was made for a model Indonesian CPO mill in several bio-waste treatment options. Main findings were that, first; over 70% of FFB was bio-wastes generated from CPO mills. Second, some mills introduced a zero emission bio-waste policy. However, untreated bio-wastes in the zero emission policy, such as, CH4 from POME ponds, may have potential to reduce more impacts on the environment. Introduction Indonesia is one of the world leaders in palm oil production with approximately 12.4 million tons of crude palm oil (CPO) production in 2005 and with the plantation area 5.6 million ha spreading out in 19 provinces [10]. The expansion of palm oil cultivation in Indonesia and its export oriented industry heavily relies on the strong world market demand for food. Currently, there are 320 CPO industries in Indonesia [10]. These include plantations and palm oil related factories. Among them, there are six biggest players in CPO business in Indonesia: PT. Perkebunan Nusantara (PTPN) consisting of 9 PTPN, Sinar Mas, Raja Garuda Mas, Astra Agro Lestari, Minamas Plantation and Indofood. They are managing more than 50% of plantation estate in Indonesia and are leading the Indonesian palm oil business.Palm oil industry is an industry to be considered when it comes to environmental impacts. Unfortunately, there is not so much available information related to the performance of each CPO on environmental impacts. There are reports which provide information on environmental impacts of CPO mills in South East Asian countries, but are limited to, for instance, Thailand’s cases [4 and 5] and Malaysia’s cases [1, 3, 6, 7, 9, 11 and 12]. On the other hand, similar studies on the Indonesian’s case are not well established in academic literatures. And also there is limitation on Indonesian palm oil industrial information from plantation to consumption and disposal in academic articles. There is no literature related to material flow analysis focusing on the whole Indonesian palm oil related industry. One way to describe and present the environmental impacts is through a life cycle assessment (LCA). The LCA could be used to estimate the impacts of CPO production including the stages of plantation, transportation and milling [5, 8 and 11]. However, studies on Indonesian CPO production process were not well established in academic articles. The purpose of this paper is thus to clarify environmental impacts of palm oil industry in Indonesia especially by focusing on plantation and CPO mills with consideration to various bio-waste treatments."

Jan 1, 2008

By Akihide Hosokawa

The void growth and coalescence in model materials involving a pre-existing three dimensional void array (i.e. multiple layers of a void array) was studied by X-ray computed tomography (XCT) coupled with in situ tensile deformation. To reduce the recording time, a new technique called fast tomography was employed. The model materials used in this paper were fabricated by the combination of an ultra-short pulsed laser machining system and a diffusion bonding technique, and two different types of arrays were prepared namely, FCC 1 and FCC 2 type array. This methodology allowed the authors to capture the entire process of growth and coalescence events of a void array embedded in the metal matrix. The failures in the both materials involved internal necking and shear localization. One of the highlights of this paper is that the plastic strain at the onset of void coalescence was measured for each model material. These values are in fact the adequate values to be compared with the coalescence strain predicted by existing void coalescence models such as the Brown and Embury model, the Thomason model and the Pardoen and Hutchinson model. The comparison suggested that the Brown and Embury model underestimated the coalescence in neither of the current model materials, while the Thomason model and the Pardoen and Hutchinson model showed a quite good agreement with the result for FCC 1 material. On the other hand the result from FCC 2 material agreed with none of the models probably due to the geometry of the void array that is not compatible with the existing models.

Jan 1, 2010

By Ali Tabeshian, Ragnhild E. Aune, Reza Beheshti

Today’s lithium-ion batteries (LiBs) are found in more than half of the hybrid-electric and plug-in hybrid vehicles on the marked, all-electric vehicles, and nearly all consumer electronics. As a result, recycling of LiBs will be a strategic necessity in the near future. In the present study, the feasibility of application of conventional aluminum recycling process (secondary aluminum production) as a suitable process for treatment of LiBs was studied. The overall idea is to recover aluminum, copper and lithium from a mixed waste stream of LiBs and aluminum scrap. A two-stage process, consisting of a preheating step and a melting step, were tested on cell phone batteries mixed with pure aluminum in a ratio 1:10 and the distribution of elements between the metal phase and the slag phase evaluated. The obtained results are compared and discussed based on the thermodynamic calculated by the use of the FactSage™ software version

Mar 1, 2017

By F. F. Lins

There is a large use of mercury in Brazil by the gold miners in the so called "garimpos" (non registered mining operations), where it is usual to recover the gold contained in the gravity concentrates by amalgamation, which is highly deleterious to environment if not conducted properly. Unfortunately, this is a common practice there. After presenting in brief the modus operandi generally practiced in the garimpos and the environmental problems, this work reviews some of the research conducted in CETEM according to two approaches: (i) replace amalgamation by other processes and (ii) develop technology to treat mercury-contaminated soils and effluents. Conventional processes like froth flotation, to recover gold from gravity concentrates, and centrifuges were considered. Also as alternatives to amalgamation, innovative process like the recovery of gold by coal-oil agglomerates and a technology that is currently under development in our laboratory, called gold-paraffin process, are described in brief, some results presented and their potential use assessed. To reclaim sites already polluted a technology was developed to float mercury selectively from contaminated soils. The potential use of centrifuges to pre-concentrate the mercury is also discussed. The scope for applying the last techniques is to concentrate the pollutants in a small volume of mass which would be suitable for recycling or isolation from the environment. A prospective technology to treat contaminated soils, or mercury concentrates, is the immobilization of mercury by adding inorganics. Concerning the ionic mercury which may be present in effluents, precipitation of the ions and flotation of the precipitates are being studied.

Jan 1, 1994

By Jesús Contreras

Since the commencement of its activities in Huelva in 1970, Atlantic Copper has maintained a course of action that has been more demanding than the successive environmental legislations current at different times. As its primary objective it has sought compatibility between the protection of the environment and both its industrial activity and the social and economic development of the area in which its Metallurgical Complex is located. For this reason, since the seventies it has maintained a continuous programme of investments which have allowed it to attain its present environmental situation. As a consequence of the Environmental Policy of Atlantic Copper, in April 1998 it obtained certification for its Integrated System of Environmental Management (SIGMA) according to international standard IS0-14001, and under European Community Regulation 1836/93 (replaced by the 76112001) for the Eco-Management and Eco-Audit System (EMAS). The SIGMA formalises the environmental management practices of Atlantic Copper and engages it to have available a system that can be fully audited. Atlantic Copper was the first European Company in the non-ferrous metallurgical sector to obtain both the UNE-EN-ISO 14001 certification and the EMAS registration. The present paper reviews the actions by Atlantic Copper in environmental matters that have allowed it to achieve its present position. It also describes the coming stages of improvement planned and the modifications to be carried out in the near future, in particular the criteria for the selection of technologies on the basis of the concept of BAT (Best Available Techniques) introduced by the European Union, and always guided by the final objective of converting Atlantic Copper into a reference within the sector, comparable to the best designed and operated installations in the world.

Jan 1, 2003

By S. q. Honingh, G. Van Weert

Currently produced zinc-enriched blast furnace dust is stored on site at CORUS IJmuiden. To end this practise, a research program was started in 1996. Four technologies were studied: oxidative autoclave leaching in a chloride medium, fluid bed pyrohydrochloridisation (pyrohydrolysis) to yield lead-zinc-free (hematite) calcine, EAF (plasma) smelting/zinc fuming, and incorporation of the dust in 'iron foundry cupola charges. All aim to remove zinc and lead, recycle the iron residue internally, and produce a saleable zinc-lead product.

Jan 1, 2000

By Fuming Wang, Changrong Li, Dan Wu, Wei Shen, Yaxu Zheng

In order to improve the oxidation resistance of Cr–Mo–V steel for high-speed railway brake discs, a higher Cr was added to the steel. Effect of temperature on the oxidation behavior of brake disc steel with different Cr contents was studied by OM, SEM and XRD. The results show that the oxidation curves at 500 °C obey a linear oxidation law in 0–2 h and 2–20 h, respectively. The oxide layer is thin and the oxidation products are Fe2O3 and Fe3O4. The oxidation curve at 700 °C follows a linear law within 2 h. With the oxidation time extending, the oxidation curves follow a parabolic law and the oxide layer becomes thicker. Moreover, the oxide layer is divided into two layers. The outer oxide layer is loose and is mainly Fe2O3, while the inner layer is denser and consists of FeO and FeCr2O4. The oxide layer thickness reduces and the oxidation resistance of the steel is improved with Cr content is increased.

Mar 1, 2018

By F. Leuzzi

Asbestos is a natural mineral fibre which has been known and utilized commercially for about a century. From the forties, it was employed on an ever-increasing scale throughout the mechanical engineering, building, paper-making and plastics sectors, to name but a few. There are essentially five minerals which provide fibres for industrial applications, namely, the chrysotile variety of serpentine and the amphiboles such as riebeckite, anthophyllite, cummingtonite-grunerite (amosite) and tremolite. About a fifth of the world's asbestos output was once taken by Europe for the manufacture of asbestos-cement products, reinforced plastics, paper and cardboard, panels, soft insulation and spray-on powders. However, in the sixties and seventies the hypothesis regarding the pathogenic nature of asbestos fibres started to gain ground. Moreover, between the sixties and eighties the EU issued a series of regulations designed to bring about a steady decrease in asbestos consumption. This line of action has culminated in recent years in a whole set of directives banning the use of asbestos in all products. This created a major problem, namely, how to clean-up the several million tons of various types of asbestos products in various states of conservation existing in Western Europe. CORDIAM (Pat. RM95 A 000269 and Pat. RM96 A 000782 in the name of ECOTEC S.r.1.) is one of the thermal inertization techniques recently proposed for this purpose. The process provides for the low-temperature ceramization of the toxic-harmful material. Of course, with such a great variety of waste materials and the volumes to be treated, as well as the need to ensure the correct dimensional design of the thermal sections of the treatment plant, it is necessary to know as much as possible about the thermal behaviour of the wastes concerned. This paper details the steps taken firstly to ascertain the thermal behaviour of such materials as may be encountered in day-to-day practice and secondly to examine the influence of the main process parameters on the preliminary design of gas- or fuel-oil-fired rotary kilns of the kind used for waste treatment.

Jan 1, 1999

By Margarete Kalin

Mine abandonment is associated with the securing of access to underground workings, shafts, raises and adits. Waste rock piles and tailings are generally contoured and revegetated. When the waste materials contain pyritic material seepages can often emerge long after the physical reclamation work has been carried out. Their extent and origin has to be delineated to facilitate remedial measures. The depth to which the seepages extended can be determined with an electromagnetic (EM) survey. This paper reports on the experience gained using a winter and a summer EM survey correlated with measurements of specific conductivity at the sediment water interface. Lake sediments and ponds which represent a homogenous background material are good media, where specific conductivity and electromagnetic conductivity can be correlated. The origin of the seepage within the recontoured mine site requires detailed site knowledge, as many anomalies in heterogenous materials such as represented by a mine site are evident.

Jan 1, 1994